Measurement of magnetic moment via optical transmission
NASA Astrophysics Data System (ADS)
Heidsieck, Alexandra; Schmid, Daniel; Gleich, Bernhard
2016-03-01
The magnetic moment of nanoparticles is an important property for drug targeting and related applications as well as for the simulation thereof. However, the measurement of the magnetic moment of nanoparticles, nanoparticle-virus-complexes or microspheres in solution can be difficult and often yields unsatisfying or incomparable results. To measure the magnetic moment, we designed a custom measurement device including a magnetic set-up to observe nanoparticles indirectly via light transmission in solution. We present a simple, cheap device of manageable size, which can be used in any laboratory as well as a novel evaluation method to determine the magnetic moment of nanoparticles via the change of the optical density of the particle suspension in a well-defined magnetic gradient field. In contrast to many of the established measurement methods, we are able to observe and measure the nanoparticle complexes in their natural state in the respective medium. The nanoparticles move along the magnetic gradient and thereby away from the observation point. Due to this movement, the optical density of the fluid decreases and the transmission increases over time at the measurement location. By comparing the measurement with parametric simulations, we can deduce the magnetic moment from the observed behavior.
Measurement of the Ω- magnetic moment
NASA Astrophysics Data System (ADS)
Diehl, H. T.; Teige, S.; Thomson, G. B.; Zou, Y.; James, C.; Luk, K. B.; Rameika, R.; Ho, P. M.; Longo, M. J.; Nguyen, A.; Duryea, J.; Guglielmo, G.; Johns, K.; Heller, K.; Thorne, K.
1991-08-01
A sample of 24 700 Ω- hyperons was produced by a prolarized neutral beam in a spin-transfer reaction. The Ω- polarizations are found to be -0.054+/-0.019 and -0.149+/-0.055 at mean Ω- momenta of 322 and 398 GeV/c, respectively. The directions of these polarizations give an Ω- magnetic moment of -(1.94+/-0.17+/-0.14)μN
Photospheric Magnetic Diffusion by Measuring Moments of Active Regions
NASA Astrophysics Data System (ADS)
Engell, Alexander; Longcope, D.
2013-07-01
Photospheric magnetic surface diffusion is an important constraint for the solar dynamo. The HMI Active Region Patches (HARPs) program automatically identify all magnetic regions above a certain flux. In our study we measure the moments of ARs that are no longer actively emerging and can thereby give us good statistical constraints on photospheric diffusion. We also present the diffusion properties as a function of latitude, flux density, and single polarity (leading or following) within each HARP.
Precise measurement of the positive muon anomalous magnetic moment
NASA Astrophysics Data System (ADS)
Deng, Huaizhang
A precise measurement of the anomalous magnetic moment, am = (g - 2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. Highly polarized m+ of 3.09 GeV/c from a secondary beam line are injected through a superconducting inflector into a storage ring 14.2 m in diameter. The superferric storage ring has a homogeneous magnetic field of 1.45 T, which is measured by an NMR (nuclear magnetic resonance) system relative to the free proton NMR angular frequency wp . The muon spin precesses faster than its momentum rotates by an angular frequency wa in the magnetic field. The frequency wa is determined by measuring the decay positrons from the stored muons. The value of the muon anomalous magnetic moment is obtained by am =wae mmcB , 1 where is the magnetic field weighted over the union distribution in space and time, e and mm are the charge and the the mass of the union, and c is the speed of light in vacuum. During the data-taking period in 1999, the number of collected positrons increased by a factor of 20 compared to the previous data-taking period in 1998. The result from the data taken in 1999, am+=11659 202146 x10-101.3 ppm, 2 is in good agreement with previous measurements and reduces the combined error by a factor of about 3. The difference between the weighted mean of all experimental results, am (exp) = 11 659 203(15) x 10-10, and the theoretical value from the standard model, am (SM) = 11 659 176.6(6.7) x 10-10, is amexp -amSM =2616x10-10 . 3 The error is the addition in quadrature of experimental and theoretical uncertainties. The difference is 1.6 times the stated error.
Improved measurement of the positive muon anomalous magnetic moment
NASA Astrophysics Data System (ADS)
Brown, H. N.; Bunce, G.; Carey, R. M.; Cushman, P.; Danby, G. T.; Debevec, P. T.; Deng, H.; Deninger, W.; Dhawan, S. K.; Druzhinin, V. P.; Duong, L.; Earle, W.; Efstathiadis, E.; Fedotovich, G. V.; Farley, F. J.; Giron, S.; Gray, F.; Grosse-Perdekamp, M.; Grossmann, A.; Haeberlen, U.; Hare, M. F.; Hazen, E. S.; Hertzog, D. W.; Hughes, V. W.; Iwasaki, M.; Jungmann, K.; Kawall, D.; Kawamura, M.; Khazin, B. I.; Kindem, J.; Krienen, F.; Kronkvist, I.; Larsen, R.; Lee, Y. Y.; Logashenko, I.; McNabb, R.; Meng, W.; Mi, J.; Miller, J. P.; Morse, W. M.; Onderwater, C. J.; Orlov, Y.; Özben, C.; Polly, C.; Pai, C.; Paley, J. M.; Pretz, J.; Prigl, R.; Zu Putlitz, G.; Redin, S. I.; Rind, O.; Roberts, B. L.; Ryskulov, N.; Sedykh, S.; Semertzidis, Y. K.; Shatunov, Yu. M.; Solodov, E.; Sossong, M.; Steinmetz, A.; Sulak, L. R.; Timmermans, C.; Trofimov, A.; Urner, D.; von Walter, P.; Warburton, D.; Winn, D.; Yamamoto, A.; Zimmerman, D.
2000-11-01
A new measurement of the positive muon's anomalous magnetic moment has been made at the Brookhaven Alternating Gradient Synchrotron using the direct injection of polarized muons into the superferric storage ring. The angular frequency difference ωa between the angular spin precession frequency ωs and the angular orbital frequency ωc is measured as well as the free proton NMR frequency ωp. These determine R=ωa/ωp=3.707 201(19)×10-3. With μμ/μp=3.183 345 39(10) this gives aμ+=11 659 191(59)×10-10 (+/-5 ppm), in good agreement with the previous CERN and BNL measurements for μ+ and μ-, and with the standard model prediction.
Re-creating Gauss's method for non-electrical absolute measurements of magnetic fields and moments
NASA Astrophysics Data System (ADS)
Van Baak, D. A.
2013-10-01
In 1832, Gauss made the first absolute measurements of magnetic fields and of magnetic moments in experiments that are straightforward and instructive to replicate. We show, using rare-earth permanent magnets and a variation of Gauss's technique, that the horizontal component of the ambient geomagnetic field, as well as the size of the magnetic moments of such magnets, can be found. The method shows the connection between the SI and cgs emu unit systems for these quantities and permits an absolute realization of the Ampere with considerable precision.
Direct high-precision measurement of the magnetic moment of the proton.
Mooser, A; Ulmer, S; Blaum, K; Franke, K; Kracke, H; Leiteritz, C; Quint, W; Rodegheri, C C; Smorra, C; Walz, J
2014-05-29
One of the fundamental properties of the proton is its magnetic moment, µp. So far µp has been measured only indirectly, by analysing the spectrum of an atomic hydrogen maser in a magnetic field. Here we report the direct high-precision measurement of the magnetic moment of a single proton using the double Penning-trap technique. We drive proton-spin quantum jumps by a magnetic radio-frequency field in a Penning trap with a homogeneous magnetic field. The induced spin transitions are detected in a second trap with a strong superimposed magnetic inhomogeneity. This enables the measurement of the spin-flip probability as a function of the drive frequency. In each measurement the proton's cyclotron frequency is used to determine the magnetic field of the trap. From the normalized resonance curve, we extract the particle's magnetic moment in terms of the nuclear magneton: μp = 2.792847350(9)μN. This measurement outperforms previous Penning-trap measurements in terms of precision by a factor of about 760. It improves the precision of the forty-year-old indirect measurement, in which significant theoretical bound state corrections were required to obtain µp, by a factor of 3. By application of this method to the antiproton magnetic moment, the fractional precision of the recently reported value can be improved by a factor of at least 1,000. Combined with the present result, this will provide a stringent test of matter/antimatter symmetry with baryons.
NASA Astrophysics Data System (ADS)
Gómez, A. M.; Torres, D. A.
2016-07-01
The experimental study of nuclear magnetic moments, using the Transient Field technique, makes use of spin-orbit hyperfine interactions to generate strong magnetic fields, above the kilo-Tesla regime, capable to create a precession of the nuclear spin. A theoretical description of such magnetic fields is still under theoretical research, and the use of parametrizations is still a common way to address the lack of theoretical information. In this contribution, a review of the main parametrizations utilized in the measurements of Nuclear Magnetic Moments will be presented, the challenges to create a theoretical description from first principles will be discussed.
Egan, R; Philippe, M; Wera, L; Fagnard, J F; Vanderheyden, B; Dennis, A; Shi, Y; Cardwell, D A; Vanderbemden, P
2015-02-01
We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm(3)) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m(2) (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K). PMID:25725888
NASA Astrophysics Data System (ADS)
Egan, R.; Philippe, M.; Wera, L.; Fagnard, J. F.; Vanderheyden, B.; Dennis, A.; Shi, Y.; Cardwell, D. A.; Vanderbemden, P.
2015-02-01
We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm3) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m2 (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K).
Stone, N. J.
2015-09-15
The most recent tabulations of nuclear magnetic dipole and electric quadrupole moments have been prepared and published by the Nuclear Data Section of the IAEA, Vienna [N. J. Stone, Report No. INDC(NDS)-0650 (2013); Report No. INDC(NDS)-0658 (2014)]. The first of these is a table of recommended quadrupole moments for all isotopes in which all experimental results are made consistent with a limited number of adopted standards for each element; the second is a combined listing of all measurements of both moments. Both tables cover all isotopes and energy levels. In this paper, the considerations relevant to the preparation of both tables are described, together with observations as to the importance and (where appropriate) application of necessary corrections to achieve the “best” values. Some discussion of experimental methods is included with emphasis on their precision. The aim of the published quadrupole moment table is to provide a standard reference in which the value given for each moment is the best available and for which full provenance is given. A table of recommended magnetic dipole moments is in preparation, with the same objective in view.
The measurement of the anomalous magnetic moment of the muon at Fermilab
Logashenko, I.
2015-06-17
The anomalous magnetic moment of the muon is one of the most precisely measured quantities in experimental particle physics. Its latest measurement at Brookhaven National Laboratory deviates from the Standard Model expectation by approximately 3.5 standard deviations. The goal of the new experiment, E989, now under construction at Fermilab, is a fourfold improvement in precision. Furthermore, we discuss the details of the future measurement and its current status.
Effective Lagrangian approach to precision measurements: Anomalous magnetic moment of the muon
Arzt, C.; Einhorn, M.B. Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 ); Wudka, J. )
1994-02-01
We investigate the use of effective Lagrangians to describe the effects on high-precision observables of physics beyond the standard model. Using the anomalous magnetic moment of the muon as an example, we detail the use of effective vertices in loop calculations. We then provide estimates of the sensitivity of new experiments measuring the muon's [ital g][minus]2 to the scale of physics underlying the standard model.
Z = 50 core stability in 110Sn from magnetic-moment and lifetime measurements
Kumbartzki, G. J.; Benczer-Koller, N.; Speidel, K. -H.; Torres, D. A.; Allmond, James M.; Fallon, P.; Abramovic, I.; L. A. Bernstein; Bevins, J. E.; Crawford, H. L.; et al
2016-04-18
In this study, the structure of the semimagic Sn50 isotopes were previously studied via measurements of B(E2;21+ → 01+) and g factors of 21+ states. The values of the B(E2;21+) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. This work presents the first measurement of the 21+ and 41+ states' magnetic moments in the unstable neutron-deficient 110Sn. The g factors provide complementary structure information to the interpretation of the observed B(E2) values.
New Measurement of the Anomalous Magnetic Moment of the Positive Muon
NASA Astrophysics Data System (ADS)
Carey, R. M.; Earle, W.; Efstathiadis, E.; Hare, M. F.; Hazen, E. S.; Hughes, B. J.; Krienen, F.; Miller, J. P.; Monich, V.; Ouyang, J.; Rind, O.; Roberts, B. L.; Sulak, L. R.; Trofimov, A.; Varner, G.; Worstell, W. A.; Benedict, E.; Logashenko, I.; Benante, J.; Brown, H. N.; Bunce, G.; Cullen, J.; Danby, G. T.; Geller, J.; Hseuh, H.; Jackson, J. W.; Jia, L.; Kochis, S.; Larsen, R.; Lee, Y. Y.; Mapes, M.; Meng, W.; Morse, W. M.; Pai, C.; Pearson, C.; Polk, I.; Prigl, R.; Rankowitz, S.; Sandberg, J.; Semertzidis, Y. K.; Shutt, R.; Snydstrup, L.; Soukas, A.; Stillman, A.; Tallerico, T.; Tanaka, M.; Toldo, F.; von Lintig, D.; Warburton, D.; Woodle, K.; Chertovskikh, A.; Druzhinin, V. P.; Fedotovich, G. V.; Grigorev, D. N.; Golubev, V. B.; Khazin, B. I.; Maksimov, A.; Merzliakov, Yu.; Ryskulov, N.; Serednyakov, S.; Shatunov, Yu. M.; Solodov, E.; Orlov, Y.; Winn, D.; Grossmann, A.; Gerhaeuser, J.; Jungmann, K.; von Walter, P.; Zu Putlitz, G.; Bunker, B.; Deninger, W.; Debevec, P. T.; Hertzog, D. W.; Jones, T. D.; Polly, C.; Sedykh, S.; Urner, D.; Haeberlen, U.; Endo, K.; Hirabayashi, H.; Kurokawa, S.; Yamamoto, A.; Green, M. A.; Cushman, P.; Kindem, J.; Duong, L.; Giron, S.; McNabb, R.; Miller, D.; Timmermans, C.; Zimmerman, D.; Mizumachi, Y.; Iwasaki, M.; Ahn, H. E.; Deng, H.; Dhawan, S. K.; Disco, A.; Farley, F. J.; Fei, X.; Grosse-Perdekamp, M.; Hughes, V. W.; Kawall, D.; Redin, S. I.; Steinmetz, A.
1999-02-01
The muon anomalous magnetic moment has been measured in a new experiment at Brookhaven. Polarized muons were stored in a superferric ring, and the angular frequency difference, ωa, between the spin precession and orbital frequencies was determined by measuring the time distribution of high-energy decay positrons. The ratio R of ωa to the Larmor precession frequency of free protons, ωp, in the storage-ring magnetic field was measured. We find R = 3.707 220\\(48\\)×10-3. With μμ/μp = 3.183 345 47\\(47\\) this gives aμ+ = 1 165 925\\(15\\)×10-9 ( +/-13 ppm), in good agreement with the previous CERN measurements for μ+ and μ- and of approximately the same precision.
A new software for the measurement of magnetic moments using SQUID and spinner magnetometers
NASA Astrophysics Data System (ADS)
Wack, M.
2010-09-01
A new software package, called CryoMag, facilitates the measurement of magnetic moments using both 3-component (i.e. Superconducting QUantum Interference Device) and 2-component (i.e. spinner) magnetometers. The measurement process is optimized for, but not limited to, stepwise demagnetization experiments commonly used in paleomagnetism. A graphical representation of the data is always visible to the user in the form of orthogonal, stereonet and decay diagrams, which can be represented in in situ, geographic or tilt corrected coordinates and can be saved as graphics files. Instrument specific settings, as well as arbitrary measurement positions, can be easily customized in a single configuration file. A comprehensive record of detailed measurement and statistical data is stored in XML (eXtensible Markup Language) based data files (*.cmag.xml). The final results of the measurements can be exported to several common file formats for further processing. The software is written in Python, an open source, cross-platform programming language and can therefore be used on popular operating systems like Windows, Linux and MacOS X. The complete source code is available on request from the author. The CryoMag open-source allows anyone to adapt the software to their specific equipment, file format and experimental requirements.
A new software for the measurement of magnetic moments using a SQUID magnetometer
NASA Astrophysics Data System (ADS)
Wack, M.
2009-12-01
A new software package called CryoMag to carry out measurements of magnetic moments is presented. It is designed to work with SQUID magnetometers manufactured by 2G Enterprises, but the modular design allows easy adaption to other instruments like spinner magnetometers as well. The measurement process is optimized for, but not limited to, stepwise demagnetization experiments commonly used in paleomagnetism. A graphical representation of the data is always visible to the user in the form of orthogonal, stereographic and decay plots, which can be represented in in-situ, geographic or tilt corrected coordinates and can be saved to graphics files. Measurement positions can be easily customized. A comprehensive record of detailed measurement and statistical data is stored in XML (eXtensible Markup Language) based data files (*.cmag.xml). The final results of the measurements can be exported to various common file formats for further processing. The software is written in Python, an open source, cross-platform programming language and can therefore be used on all major operating systems like Windows, Linux and MacOS X (not tested).
Yukhimchuk, A.A.; Vinogradov, Yu.I.; Golubkov, A.N.; Grishechkin, S.K.; Il'kaev, R.I.; Kuryakin, A.V.; Lebedev, B.L.; Lobanov, V.N.; Mikhailov, V.N.; Tumkin, D.P.; Bogdanova, L.N.
2005-07-15
For the experiment on the measurement of the electron antineutrino magnetic moment we suggest a new approach to the tritium source design, namely, a configuration of annular cells filled with TiT{sub 2} that are stacked into a hollow cylinder. Detectors are mounted in the hole inside.We present results of the optimization of geometrical and physical parameters of the source with respect to its experimental effectiveness and safety guaranty at all stages of its lifecycle. We discuss the choice of the construction materials and specify technological issues relevant to radiation purity of the source, being of the special concern in the experiment on the electron antineutrino magnetic moment measurement.
Magnetic moments in graphene with vacancies.
Chen, Jing-Jing; Wu, Han-Chun; Yu, Da-Peng; Liao, Zhi-Min
2014-08-01
Vacancies can induce local magnetic moments in graphene, paving the way to make magnetic functional graphene. Due to the interaction between magnetic moments and conduction carriers, the magnetotransport properties of graphene can be modulated. Here, the effects of vacancy induced magnetic moments on the electrical properties of graphene are studied via magnetotransport measurements and spin-polarized density functional theory calculations. We show by quantum Hall measurements that a sharp resonant Vπ state is introduced in the midgap region of graphene with vacancies, resulting in the local magnetic moment. The coupling between the localized Vπ state and the itinerant carrier is tuned by varying the carrier concentration, temperature, magnetic field, and vacancy density, which results in a transition between hopping transport and the Kondo effect and a transition between giant negative magnetoresistance (MR) and positive MR. This modulated magnetotransport is valuable for graphene based spintronic devices.
Magnetic moments in graphene with vacancies
NASA Astrophysics Data System (ADS)
Chen, Jing-Jing; Wu, Han-Chun; Yu, Da-Peng; Liao, Zhi-Min
2014-07-01
Vacancies can induce local magnetic moments in graphene, paving the way to make magnetic functional graphene. Due to the interaction between magnetic moments and conduction carriers, the magnetotransport properties of graphene can be modulated. Here, the effects of vacancy induced magnetic moments on the electrical properties of graphene are studied via magnetotransport measurements and spin-polarized density functional theory calculations. We show by quantum Hall measurements that a sharp resonant Vπ state is introduced in the midgap region of graphene with vacancies, resulting in the local magnetic moment. The coupling between the localized Vπ state and the itinerant carrier is tuned by varying the carrier concentration, temperature, magnetic field, and vacancy density, which results in a transition between hopping transport and the Kondo effect and a transition between giant negative magnetoresistance (MR) and positive MR. This modulated magnetotransport is valuable for graphene based spintronic devices.
Z =50 core stability in 110Sn from magnetic-moment and lifetime measurements
NASA Astrophysics Data System (ADS)
Kumbartzki, G. J.; Benczer-Koller, N.; Speidel, K.-H.; Torres, D. A.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; Bevins, J. E.; Crawford, H. L.; Guevara, Z. E.; Gürdal, G.; Hurst, A. M.; Kirsch, L.; Laplace, T. A.; Lo, A.; Matthews, E. F.; Mayers, I.; Phair, L. W.; Ramirez, F.; Robinson, S. J. Q.; Sharon, Y. Y.; Wiens, A.
2016-04-01
Background: The structure of the semimagic 50Sn isotopes were previously studied via measurements of B (E 2 ;21+→01+ ) and g factors of 21+ states. The values of the B (E 2 ;21+ ) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. Purpose: This work presents the first measurement of the 2 1+ and 4 1+ states' magnetic moments in the unstable neutron-deficient 110Sn. The g factors provide complementary structure information to the interpretation of the observed B (E 2 ) values. Methods: The 110Sn nuclei have been produced in inverse kinematics in an α -particle transfer reaction from 12C to 106Cd projectiles at 390, 400, and 410 MeV. The g factors have been measured with the transient field technique. Lifetimes have been determined from line shapes using the Doppler-shift attenuation method. Results: The g factors of the 21+ and 41+ states in 110Sn are g (21+) = +0.29(11) and g (41+) = +0.05(14), respectively. In addition, the g (41+) = +0.27(6) in 106Cd has been measured for the first time. A line-shape analysis yielded τ (110Sn ; 21+) = 0.81(10) ps and a lifetime of τ (110Sn ; 31-) = 0.25(5) ps was calculated from the fully Doppler-shifted γ line. Conclusions: No evidence has been found in 110Sn that would require excitation of protons from the closed Z =50 core.
Fradin, Cécile
2013-01-01
Magnetotactic bacteria possess organelles called magnetosomes that confer a magnetic moment on the cells, resulting in their partial alignment with external magnetic fields. Here we show that analysis of the trajectories of cells exposed to an external magnetic field can be used to measure the average magnetic dipole moment of a cell population in at least five different ways. We apply this analysis to movies of Magnetospirillum magneticum AMB-1 cells, and compare the values of the magnetic moment obtained in this way to that obtained by direct measurements of magnetosome dimension from electron micrographs. We find that methods relying on the viscous relaxation of the cell orientation give results comparable to that obtained by magnetosome measurements, whereas methods relying on statistical mechanics assumptions give systematically lower values of the magnetic moment. Since the observed distribution of magnetic moments in the population is not sufficient to explain this discrepancy, our results suggest that non-thermal random noise is present in the system, implying that a magnetotactic bacterial population should not be considered as similar to a paramagnetic material. PMID:24349185
Magnetic moment and lifetime measurements of Coulomb-excited states in Cd106
Benczer-Koller, N.; Kumbartzki, G. J.; Speidel, K. -H.; Torres, D. A.; Robinson, S. J. Q.; Sharon, Y. Y.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; et al
2016-09-06
The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible. Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in 106Cd. Methods: In an inverse kinematics reaction, a 106Cd beam impinging on a 12C target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure g factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for 106Cd. As a result, the g factorsmore » of the 2+1 and 4+1 states in 106Cd were measured to be g(2+1) = +0.398(22) and g(4+1) = +0.23(5). A lineshape analysis yielded lifetimes in disagreement with published values. The new results are τ(106Cd; 2+1) = 7.0(3) ps and τ(106Cd; 4+1) = 2.5(2) ps. The mean life τ(106Cd; 2+2) = 0.28(2) ps was determined from the fully-Doppler-shifted γ line. Mean lives of τ(106Cd; 4+3) = 1.1(1) ps and τ(106Cd; 3–1) = 0.16(1) ps were determined for the first time. In conclusion, the newly measured g(4+1) of 106Cd is found to be only 59% of the g(2+1). This difference cannot be explained by either shell-model or collective-model calculations.« less
Magnetic moment and lifetime measurements of Coulomb-excited states in 106Cd
NASA Astrophysics Data System (ADS)
Benczer-Koller, N.; Kumbartzki, G. J.; Speidel, K.-H.; Torres, D. A.; Robinson, S. J. Q.; Sharon, Y. Y.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; Bevins, J. E.; Crawford, H. L.; Guevara, Z. E.; Hurst, A. M.; Kirsch, L.; Laplace, T. A.; Lo, A.; Matthews, E. F.; Mayers, I.; Phair, L. W.; Ramirez, F.; Wiens, A.
2016-09-01
Background: The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible. Purpose: Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in 106Cd. Methods: In an inverse kinematics reaction, a 106Cd beam impinging on a 12C target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure g factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for 106Cd. Results: The g factors of the 21+ and 41+ states in 106Cd were measured to be g (21+)=+0.398 (22 ) and g (41+)=+0.23 (5 ) . A lineshape analysis yielded lifetimes in disagreement with published values. The new results are τ (106Cd;21+)=7.0 (3 )ps and τ (106Cd;41+)=2.5 (2 )ps . The mean life τ (106Cd;22+)=0.28 (2 )ps was determined from the fully-Doppler-shifted γ line. Mean lives of τ (106Cd;43+)=1.1 (1 )ps and τ (106Cd;31-)=0.16 (1 )ps were determined for the first time. Conclusions: The newly measured g (41+) of 106Cd is found to be only 59% of the g (21+) . This difference cannot be explained by either shell-model or collective-model calculations.
Makulski, W; Jackowski, K; Antusek, A; Jaszuński, M
2006-10-12
New gas-phase NMR measurements of the shielding constants of 29Si, 73Ge, and 1H nuclei in SiH4 and GeH4 are reported. The results, extrapolated to zero density, provide accurate isolated molecule values, best suited for comparison with theoretical calculations. Using the recent ab initio results for these molecules and the measured chemical shifts, we determine the absolute shielding scales for 29Si and 73Ge. This allows us to provide new values of the nuclear magnetic dipole moments for these two nuclei; in addition, we examine the dipole moments of 13C and 119Sn.
Magnetic Dipole Moment Measurements of Picosecond States in Even and Odd Heavy Nuclei
NASA Astrophysics Data System (ADS)
Ballon, Douglas Jude
The perturbed angular correlation and transient field technique is used to measure the precession of nuclear magnetic moments of low lying excited states in isotopes of silver, neodymium, samarium, and gadolinium. The precession measurements are used to explore three main areas of study. First, from the measurements made on ('150)Sm traversing gadolinium targets, the temperature dependence of the transient hyperfine field is deduced at ('150)Sm nuclei traveling at 2 < v/v(,0) < 4. These are compared with similar measurements made using iron targets. Second, the deduced values of the g-factors of the 2(,1)('+) states in even neodymium, samarium and gadolinium isotopes are discussed in connection with a possible proton shell closure at Z = 64. Third, the deduced values of the g-factors of the 3/2(,1)('-) and 5/2(,1)('-) states of ('107,109)Ag are compared to various theoretical predictions in order to explore any simple relationships that may exist between these states and the first 2(,1)('+) states of neighboring even-even nuclei. The following is a list of g-factors that were measured during the course of this work: (UNFORMATTED TABLE FOLLOWS). g(('107)Ag, 3/2(,1)('-)) = 0.607 (119). g(('109)Ag, 3/2(,1)('-)) = 0.661 (105). g(('107)Ag, 5/2(,1)('-)) = 0.409 (66). g(('109)Ag, 5/2(,1)('-)) = 0.287 (57). g(('144)Nd, 2(,1)('+)) = 0.166 (41). g(('146)Nd, 2(,1)('+)) = 0.312 (49). g(('148)Nd, 2(,1)('+)) = 0.411 (42). g(('150)Nd,2(,1)('+)) = 0.418 (38). g(('148)Sm, 2(,1)('+)) = 0.301 (33). g(('150)Sm, 2(,1)('+)) = 0.381 (27). g(('152)Gd, 2(,1)('+)) = 0.444 (40). (TABLE ENDS). The results of the temperature dependence experiment show deviations from an earlier measurement made using thulium in iron. The g-factors measured in the lighter isotopes of neodymium and samarium are significantly below the collective Z/A value. Fair agreement with the data can be obtained if proton shell closure is assumed at Z = 64 for N < 88. The measured g-factors in the silver isotopes
NASA Astrophysics Data System (ADS)
Afach, S.; Baker, C. A.; 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.
2015-10-01
We report on the measurement of a Larmor frequency shift proportional to the electric-field strength for 199Hg 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.
Bonanos, Peter
1983-01-01
A toroidal magnet for confining a high magnetic field for use in fusion reactor research and nuclear particle detection. The magnet includes a series of conductor elements arranged about and fixed at its small major radius portion to the outer surface of a central cylindrical support each conductor element having a geometry such as to maintain the conductor elements in pure tension when a high current flows therein, and a support assembly which redistributes all or part of the tension which would otherwise arise in the small major radius portion of each coil element to the large major radius portion thereof.
Determination of the Neutron Magnetic Moment
DOE R&D Accomplishments Database
Greene, G. L.; Ramsey, N. F.; Mampe, W.; Pendlebury, J. M.; Smith, K.; Dress, W. B.; Miller, P. D.; Perrin, P.
1981-06-01
The neutron magnetic moment has been measured with an improvement of a factor of 100 over the previous best measurement. Using a magnetic resonance spectrometer of the separated oscillatory field type capable of determining a resonance signal for both neutrons and protons (in flowing H{sub 2}O), we find ..mu..{sub n}/..mu..{sub p} = 0.68497935(17) (0.25 ppM). The neutron magnetic moment can also be expressed without loss of accuracy in a variety of other units.
NASA Technical Reports Server (NTRS)
Stuart, Keith; Bartosh, Blake
1993-01-01
Innovative Information Systems (IIS), Inc. is in the process of designing and fabricating a high bandwidth force and moment measuring device (i.e. the Magnetic Thruster Test Stand). This device will use active magnetic suspension to allow direct measurements of the forces and torques generated by the rocket engines of the missile under test. The principle of operation of the Magnetic Thruster Test Stand (MTTS) is based on the ability to perform very precise, high bandwidth force and position measurements on an object suspended in a magnetic field. This ability exists due to the fact that the digital servo control mechanism that performs the magnetic suspension uses high bandwidth (10 kHz) position data (via an eddy-current proximity sensor) to determine the amount of force required to maintain stable suspension at a particular point. This force is converted into required electromagnet coil current, which is then output to a current amplifier driving the coils. A discussion of how the coil current and magnetic gap distance (the distance between the electromagnet and the object being suspended) is used to determine the forces being applied from the suspended assembly is presented.
Updating neutrino magnetic moment constraints
NASA Astrophysics Data System (ADS)
Cañas, B. C.; Miranda, O. G.; Parada, A.; Tórtola, M.; Valle, J. W. F.
2016-02-01
In this paper we provide an updated analysis of the neutrino magnetic moments (NMMs), discussing both the constraints on the magnitudes of the three transition moments Λi and the role of the CP violating phases present both in the mixing matrix and in the NMM matrix. The scattering of solar neutrinos off electrons in Borexino provides the most stringent restrictions, due to its robust statistics and the low energies observed, below 1 MeV. Our new limit on the effective neutrino magnetic moment which follows from the most recent Borexino data is 3.1 ×10-11μB at 90% C.L. This corresponds to the individual transition magnetic moment constraints: |Λ1 | ≤ 5.6 ×10-11μB, |Λ2 | ≤ 4.0 ×10-11μB, and |Λ3 | ≤ 3.1 ×10-11μB (90% C.L.), irrespective of any complex phase. Indeed, the incoherent admixture of neutrino mass eigenstates present in the solar flux makes Borexino insensitive to the Majorana phases present in the NMM matrix. For this reason we also provide a global analysis including the case of reactor and accelerator neutrino sources, presenting the resulting constraints for different values of the relevant CP phases. Improved reactor and accelerator neutrino experiments will be needed in order to underpin the full profile of the neutrino electromagnetic properties.
Ouedraogo, Serge Aristide
2008-12-01
A search for the muon neutrino magnetic moment was conducted using the Mini-BooNE low energy neutrino data. The analysis was performed by analyzing the elastic scattering interactions of muon neutrinos on electrons. The analysis looked for an excess of elastic scattering events above the Standard Model prediction from which a limit on the neutrino magnetic could be set. In this thesis, we report an excess of 15.3 ± 6.6(stat)±4.1(syst) v_{μ}e events above the expected background. At 90% C.L., we derived a limit on the muon neutrino magnetic moment of 12.7 x 10^{-10} μ_{B}. The other analysis reported in this thesis is a measurement of charged current single pion production (CCπ^{+}) to charged current quasi elastic (CCQE) interactions cross sections ratio. This measurement was performed with two different fitting algorithms and the results from both fitters are consistent with each other.
Cai, Y. P.; Chesnel, K. Trevino, M.; Westover, A.; Turley, S.; Harrison, R. G.; Hancock, J. M.; Scherz, A.; Reid, A.; Wu, B.; Graves, C.; Wang, T.; Liu, T.; Dürr, H.
2014-05-07
The orbital and spin contributions to the magnetic moment of Fe in Fe{sub 3}O{sub 4} nanoparticles were measured using X-ray magnetic circular dichroism (XMCD). Nanoparticles of different sizes, ranging from 5 to 11 nm, were fabricated via organic methods and their magnetic behavior was characterized by vibrating sample magnetometry (VSM). An XMCD signal was measured for three different samples at 300 K and 80 K. The extracted values for the orbital and spin contributions to the magnetic moment showed a quenching of the orbital moment and a large spin moment. The calculated spin moments appear somewhat reduced compared to the value expected for bulk Fe{sub 3}O{sub 4}. The spin moments measured at 80 K are larger than at 300 K for all the samples, revealing significant thermal fluctuations effects in the nanoparticle assemblies. The measured spin moment is reduced for the smallest nanoparticles, suggesting that the magnetic properties of Fe{sub 3}O{sub 4} nanoparticles could be altered when their size reaches a few nanometers.
Detecting transition radiation from a magnetic moment.
Ivanov, Igor P; Karlovets, Dmitry V
2013-06-28
Electromagnetic radiation can be emitted not only by particle charges but also by magnetic moments and higher electric and magnetic multipoles. However, experimental proofs of this fundamental fact are extremely scarce. In particular, the magnetic moment contribution has never been observed in any form of polarization radiation. Here, we propose to detect it using vortex electrons carrying large orbital angular momentum ℓ. The relative contribution of the orbital angular momentum-induced magnetic moment, ℓℏω/Ee, becomes much larger than the spin-induced contribution ℏω/E and it can be observed experimentally. As a particular example, we consider transition radiation from vortex electrons obliquely incident on an interface between a vacuum and a dispersive medium, in which the magnetic moment contribution manifests itself via a left-right angular asymmetry. For electrons with Ee=300 keV and ℓ=100-1000, we predict an asymmetry of the order of 0.1%-1%, which could be measured with existing technology. Thus, vortex electrons emerge as a new tool in the physics of electromagnetic radiation.
Superconductivity from Emerging Magnetic Moments.
Hoshino, Shintaro; Werner, Philipp
2015-12-11
Multiorbital Hubbard models are shown to exhibit a spatially isotropic spin-triplet superconducting phase, where equal-spin electrons in different local orbitals are paired. This superconducting state is stabilized in the spin-freezing crossover regime, where local moments emerge in the metal phase, and the pairing is substantially assisted by spin anisotropy. The phase diagram features a superconducting dome below a non-Fermi-liquid metallic region and next to a magnetically ordered phase. We suggest that this type of fluctuating-moment-induced superconductivity, which is not originating from fluctuations near a quantum critical point, may be realized in spin-triplet superconductors such as strontium ruthenates and uranium compounds. PMID:26705649
Superconductivity from Emerging Magnetic Moments
NASA Astrophysics Data System (ADS)
Hoshino, Shintaro; Werner, Philipp
2015-12-01
Multiorbital Hubbard models are shown to exhibit a spatially isotropic spin-triplet superconducting phase, where equal-spin electrons in different local orbitals are paired. This superconducting state is stabilized in the spin-freezing crossover regime, where local moments emerge in the metal phase, and the pairing is substantially assisted by spin anisotropy. The phase diagram features a superconducting dome below a non-Fermi-liquid metallic region and next to a magnetically ordered phase. We suggest that this type of fluctuating-moment-induced superconductivity, which is not originating from fluctuations near a quantum critical point, may be realized in spin-triplet superconductors such as strontium ruthenates and uranium compounds.
NASA Astrophysics Data System (ADS)
Ho, P. M.; Longo, M. J.; Nguyen, A.; Luk, K. B.; James, C.; Rameika, R.; Duryea, J.; Guglielmo, G.; Heller, K.; Johns, K.; Diehl, H. T.; Teige, S.; Thomson, G. B.; Zou, Y.
1991-12-01
The polarization of Ξ¯ + hyperons produced by 800-GeV/c protons in the inclusive reaction p+Be-->Ξ¯ ++X has been measured using a sample of 70 000 Ξ¯ + decays. The average polarization of the Ξ¯ +, at a mean xF=0.39 and pt=0.76 GeV/c, is -0.097+/-0.012+/-0.009, compared to -0.102+/-0.012+/-0.010 for the Ξ-. The large polarization found for the Ξ¯ + is not expected in any model for polarization of inclusively produced hyperons. The magnetic moment of the Ξ¯ + was measured to be 0.657+/-0.028+/-0.020 nuclear magnetons (μN), compared to (-0.674+/-0.021+/-0.020)μN for the Ξ-, in good agreement with CPT invariance.
Magnetic Moments of States in 110Sn.
NASA Astrophysics Data System (ADS)
Kumbartzki, G. J.
2016-06-01
The semi-magic Sn isotopes with Z = 50 are the subject of extensive experimental and theoretical studies. The measured B(E2) values to the 21 + states for the neutron-deficient side of the isotope chain suggest enhanced collectivity when fewer particles are available if the proton shell is not broken. Magnetic moments which are sensitive to proton and neutron contributions to the wave functions of the states could provide critical and relevant information. Magnetic moments were previously measured only for the even stable and a few neutron-rich unstable Sn isotopes. A measurement of the g factors of excited states in 110Sn using the transient field technique was performed at the 88-Inch Cyclotron at the LBNL in Berkeley. The 110Sn nuclei were produced via an α-particle transfer to 106Cd.
Nuclear magnetic moment of sup 106 Rh
Ohya, S.; Ashworth, C.J.; Nawaz, Z.; Stone, N.J.; Back, P.J. )
1990-01-01
Nuclear orientation and nuclear magnetic resonance measurements have been performed for {sup 106}Rh oriented at low temperature in iron and nickel hosts. From the results of the temperature dependence measurements of nuclear orientation, the magnetic moment of {sup 106}Rh was deduced as {vert bar}{mu}({sup 106}Rh,1{sup +}){vert bar}=2.52(5){mu}{sub {ital N}}, which is very different from the value of 3.07(9) {mu}{sub {ital N}} reported previously. From the nuclear magnetic resonance on oriented nuclei measurements of {sup 106}Rh{ital Ni}, the magnetic hyperfine splitting frequency {vert bar}{ital g}{mu}{sub {ital N}}B{sub HF}/h{vert bar} was determined to be 441.5(7) MHz. Using the hyperfine field {ital B}{sub HF} (Rh{ital Ni}) of {minus}22.49(5) T, the precise value of the magnetic moment of {sup 106}Rh was deduced: {vert bar}{mu}({sup 106}Rh,1{sup +}){vert bar} =2.575(7) {mu}{sub {ital N}}. The electric quadrupole interaction has been measured using modulated adiabatic passage on oriented nuclei in a nickel single-crystal host. A broad distribution of the quadrupole splitting {Delta}{nu}{sub {ital Q}} is found, extending from 0 to 300 kHz.
How to introduce the magnetic dipole moment
NASA Astrophysics Data System (ADS)
Bezerra, M.; Kort-Kamp, W. J. M.; Cougo-Pinto, M. V.; Farina, C.
2012-09-01
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 magnetic field at distant points, identifying the magnetic dipole moment of the distribution. We also present a simple but general demonstration of the torque exerted by a uniform magnetic field on a current loop of general form, not necessarily planar. For pedagogical reasons we start by reviewing briefly the concept of the electric dipole moment.
Magnetic moment distribution of magnetic cataclysmic variables
NASA Technical Reports Server (NTRS)
Wu, Kinwah; Wickramasinghe, Dayal T.
1991-01-01
A simulation study is made of the relative numbers of the AM Herculis binaries and the intermediate polars as a function of the orbital period using random variables subject to suitable constraints to describe the various parameters. It is shown that the observations can be matched by a single distribution in the magnetic moment equals 0.7 +/- 0.3. For such an ensemble, the intermediate polars are distributed in the log(Porb) - log(Ps) diagram about the critical disk line but with a larger scatter than observed.
Tensor charge and anomalous magnetic moment correlation
Mekhfi, Mustapha
2005-12-01
We propose a generalization of the upgraded Karl-Sehgal formula which relates baryon magnetic moments to the spin structure of constituent quarks, by adding anomalous magnetic moments of quarks. We first argue that the relativistic nature of quarks inside baryons requires the introduction of two kinds of magnetisms, one axial and the other tensorial. The first one is associated with integrated quark helicity distributions {delta}{sub i}-{delta}{sub i} (standard) and the second with integrated transversity distributions {delta}{sub i}-{delta}{sub i}. The weight of each contribution is controlled by the combination of two parameters, x{sub i} the ratio of the quark mass to the average kinetic energy and a{sub i} the quark anomalous magnetic moment. The quark anomalous magnetic moment is correlated to transversity, and both are necessary ingredients in describing relativistic quarks. The proposed formula, when confronted with baryon magnetic moments data with reasonable inputs, yields, besides quark magnetic densities, anomalous magnetic moments large enough not to be ignored.
Measuring the Moment of Inertia
ERIC Educational Resources Information Center
Lehmberg, George L.
1978-01-01
Two physics experiments are described, One, involving a laboratory cart accelerated along a level surface, examines the concept of inertial mass in translation and the other, using a solid cylinder, measures the moment of inertia of a wheel. Equations and illustrations are included. (MA)
How to Introduce the Magnetic Dipole Moment
ERIC Educational Resources Information Center
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…
Carey, R.M.; Lynch, K.R.; Miller, J.P.; Roberts, B.L.; Morse, W.M.; Semertzides, Y.K.; Druzhinin, V.P.; Khazin, B.I.; Koop, I.A.; Logashenko, I.; Redin, S.I.; /Boston U. /Brookhaven /Novosibirsk, IYF /Cornell U., CIHEP /Fermilab /Frascati /Illinois U., Urbana /James Madison U. /Groningen, KVI /KEK, Tsukuba /Kentucky U.
2009-02-01
We propose to measure the muon anomalous magnetic moment, a{sub {mu}}, to 0.14 ppm-a fourfold improvement over the 0.54 ppm precision obtained in the BNL experiment E821. The muon anomaly is a fundamental quantity and its precise determination will have lasting value. The current measurement was statistics limited, suggesting that greater precision can be obtained in a higher-rate, next-generation experiment. We outline a plan to use the unique FNAL complex of proton accelerators and rings to produce high-intensity bunches of muons, which will be directed into the relocated BNL muon storage ring. The physics goal of our experiment is a precision on the muon anomaly of 16 x 10{sup -11}, which will require 21 times the statistics of the BNL measurement, as well a factor of 3 reduction in the overall systematic error. Our goal is well matched to anticipated advances in the worldwide effort to determine the standard model (SM) value of the anomaly. The present comparison, {Delta}a{sub {mu}} (Expt: -SM) = (295 {+-} 81) x 10{sup -11}, is already suggestive of possible new physics contributions to the muon anomaly. Assuming that the current theory error of 51 x 10{sup -11} is reduced to 30 x 10{sup -11} on the time scale of the completion of our experiment, a future {Delta}a{sub {mu}} comparison would have a combined uncertainty of {approx} 34 x 10{sup -11}, which will be a sensitive and complementary benchmark for proposed standard model extensions. The experimental data will also be used to improve the muon EDM limit by up to a factor of 100 and make a higher-precision test of Lorentz and CPT violation. We describe in this Proposal why the FNAL complex provides a uniquely ideal facility for a next-generation (g-2) experiment. The experiment is compatible with the fixed-target neutrino program; indeed, it requires only the unused Booster batch cycles and can acquire the desired statistics in less than two years of running. The proton beam preparations are largely aligned
Magnetic moment nonconservation in magnetohydrodynamic turbulence models.
Dalena, S; Greco, A; Rappazzo, A F; Mace, R L; Matthaeus, W H
2012-07-01
The fundamental assumptions of the adiabatic theory do not apply in the presence of sharp field gradients or in the presence of well-developed magnetohydrodynamic turbulence. For this reason, in such conditions the magnetic moment μ is no longer expected to be constant. This can influence particle acceleration and have considerable implications in many astrophysical problems. Starting with the resonant interaction between ions and a single parallel propagating electromagnetic wave, we derive expressions for the magnetic moment trapping width Δμ (defined as the half peak-to-peak difference in the particle magnetic moments) and the bounce frequency ω(b). We perform test-particle simulations to investigate magnetic moment behavior when resonance overlapping occurs and during the interaction of a ring-beam particle distribution with a broadband slab spectrum. We find that the changes of magnetic moment and changes of pitch angle are related when the level of magnetic fluctuations is low, δB/B(0) = (10(-3),10(-2)), where B(0) is the constant and uniform background magnetic field. Stochasticity arises for intermediate fluctuation values and its effect on pitch angle is the isotropization of the distribution function f(α). This is a transient regime during which magnetic moment distribution f(μ) exhibits a characteristic one-sided long tail and starts to be influenced by the onset of spatial parallel diffusion, i.e., the variance <(Δz)(2)> grows linearly in time as in normal diffusion. With strong fluctuations f(α) becomes completely isotropic, spatial diffusion sets in, and the f(μ) behavior is closely related to the sampling of the varying magnetic field associated with that spatial diffusion.
NASA Astrophysics Data System (ADS)
Baryshevsky, V. G.
2016-06-01
The use of spin rotation effect in bent crystals for measuring the magnetic moment of short-lived particles in the range of LHC and FCC energies is considered. It is shown that the estimated number of produced baryons that are captured into a bent crystal grows as ∼γ 3 / 2 with increasing particle energy. Hence it may be concluded that the experimental measurement of magnetic moments of short-lived particles using the spin rotation effect is feasible at LHC and higher energies (for LHC energies, e.g., the running time required for measuring the magnetic moment of Λc+ is 2 ÷ 16 hours).
Magnetic Moment Quantifications of Small Spherical Objects in MRI
Cheng, Yu-Chung N.; Hsieh, Ching-Yi; Tackett, Ronald; Kokeny, Paul; Regmi, Rajesh Kumar; Lawes, Gavin
2014-01-01
Purpose The purpose of this work is to develop a method for accurately quantifying effective magnetic moments of spherical-like small objects from magnetic resonance imaging (MRI). A standard 3D gradient echo sequence with only one echo time is intended for our approach to measure the effective magnetic moment of a given object of interest. Methods Our method sums over complex MR signals around the object and equates those sums to equations derived from the magnetostatic theory. With those equations, our method is able to determine the center of the object with subpixel precision. By rewriting those equations, the effective magnetic moment of the object becomes the only unknown to be solved. Each quantified effective magnetic moment has an uncertainty that is derived from the error propagation method. If the volume of the object can be measured from spin echo images, the susceptibility difference between the object and its surrounding can be further quantified from the effective magnetic moment. Numerical simulations, a variety of glass beads in phantom studies with different MR imaging parameters from a 1.5 T machine, and measurements from a SQUID (superconducting quantum interference device) based magnetometer have been conducted to test the robustness of our method. Results Quantified effective magnetic moments and susceptibility differences from different imaging parameters and methods all agree with each other within two standard deviations of estimated uncertainties. Conclusion An MRI method is developed to accurately quantify the effective magnetic moment of a given small object of interest. Most results are accurate within 10% of true values and roughly half of the total results are accurate within 5% of true values using very reasonable imaging parameters. Our method is minimally affected by the partial volume, dephasing, and phase aliasing effects. Our next goal is to apply this method to in vivo studies. PMID:25490517
Gabrielse, Gerald [Harvard University, Cambridge, Massachusetts, United States
2016-07-12
Remarkably, the famous UW measurement of the electron magnetic moment has stood since 1987. With QED theory, this measurement has determined the accepted value of the fine structure constant. This colloquium is about a new Harvard measurement of these fundamental constants. The new measurement has an uncertainty that is about six times smaller, and it shifts the values by 1.7 standard deviations. One electron suspended in a Penning trap is used for the new measurement, like in the old measurement. What is different is that the lowest quantum levels of the spin and cyclotron motion are resolved, and the cyclotron as well as spin frequencies are determined using quantum jump spectroscopy. In addition, a 0.1 mK Penning trap that is also a cylindrical microwave cavity is used to control the radiation field, to suppress spontaneous emission by more than a factor of 100, to control cavity shifts, and to eliminate the blackbody photons that otherwise stimulate excitations from the cyclotron ground state. Finally, great signal-to-noise for one-quantum transitions is obtained using electronic feedback to realize the first one-particle self-excited oscillator. The new methods may also allow a million times improved measurement of the 500 times small antiproton magnetic moment.
Electrical and Thermal Control of Magnetic Moments
NASA Astrophysics Data System (ADS)
Barnaś, J.; Balaz, P.; Dyrdał, A.; Dugaev, V. K.
Spin transport in a magnetically nonuniform structure can lead to transfer of angular momentum from conduction electrons to local magnetization. This, in turn, gives rise to a spin-transfer torque, which can modify magnetic state of the system. Another mechanism of current-induced spin torque relies on spin-orbit interactions. However, the spin torque can be induced not only by electric field driving the current, but also by a temperature gradient which drives a thermocurrent due to the thermoelectric phenomena. Both current- and thermallyinduced spin torques allow to control and manipulate magnetic moments.
Interpreting magnetic data by integral moments
NASA Astrophysics Data System (ADS)
Tontini, F. Caratori; Pedersen, L. B.
2008-09-01
The use of the integral moments for interpreting magnetic data is based on a very elegant property of potential fields, but in the past it has not been completely exploited due to problems concerning real data. We describe a new 3-D development of previous 2-D results aimed at determining the magnetization direction, extending the calculation to second-order moments to recover the centre of mass of the magnetization distribution. The method is enhanced to reduce the effects of the regional field that often alters the first-order solutions. Moreover, we introduce an iterative correction to properly assess the errors coming from finite-size surveys or interaction with neighbouring anomalies, which are the most important causes of the failing of the method for real data. We test the method on some synthetic examples, and finally, we show the results obtained by analysing the aeromagnetic anomaly of the Monte Vulture volcano in Southern Italy.
Noncommutative magnetic moment of charged particles
Adorno, T. C.; Gitman, D. M.; Shabad, A. E.; Vassilevich, D. V.
2011-10-15
It has been argued that in noncommutative field theories, the sizes of physical objects cannot be taken smaller than an ''elementary length'' related to noncommutativity parameters. By gauge covariantly extending field equations of noncommutative U(1){sub *} theory to cover the presence of external sources, we find electric and magnetic fields produced by an extended static charge. We find that such a charge, apart from being an ordinary electric monopole, is also a magnetic dipole. By writing off the existing experimental clearance in the value of the lepton magnetic moments for the present effect, we get the bound on noncommutativity at the level of 10{sup 4} TeV.
Magnetic Moment of Proton Drip-Line Nucleus (9)C
NASA Technical Reports Server (NTRS)
Matsuta, K.; Fukuda, M.; Tanigaki, M.; Minamisono, T.; Nojiri, Y.; Mihara, M.; Onishi, T.; Yamaguchi, T.; Harada, A.; Sasaki, M.
1994-01-01
The magnetic moment of the proton drip-line nucleus C-9(I(sup (pi)) = 3/2, T(sub 1/2) = 126 ms) has been measured for the first time, using the beta-NMR detection technique with polarized radioactive beams. The measure value for the magnetic moment is 1mu(C-9)! = 1.3914 +/- 0.0005 (mu)N. The deduced spin expectation value
The Magnetic Moments of the Proton and the Antiproton
NASA Astrophysics Data System (ADS)
Ulmer, Stefan; Smorra, Christian
A comparison of the magnetic moments of the proton and the antiproton provides a sensitive test of matter-antimatter symmetry. While the magnetic moment of the proton is known with a relative precision of 10^{-8}, that of the antiproton is only known with moderate accuracy. Important progress towards a high-precision measurement of the particle's magnetic moment was reported in 2011 by a group at Mainz when spin transitions of a single proton stored in a cryogenic Penning trap were observed. To resolve the single-proton spin flips, the so-called 'continuous Stern-Gerlach effect' was utilized. Using this technique, the proton magnetic moment was measured by two groups at Mainz and Harvard with relative precisions of 8.9× 10^{-6} and 2.5× 10^{-6}, respectively. Currently, two collaborations at the CERN antiproton decelerator (AD)—a part of ATRAP and BASE—are pushing their efforts to apply the methods developed for the proton to measure the magnetic moment of the antiproton. Very recently, DiSciacca et al. reported on a measurement of the antiproton's magnetic moment with a relative precision of 4.4 ppm, which is a improvement of the formerly best value by about a factor of 680. Using the so-called double Penning trap technique, both collaborations aim for a precision measurement at the level of at least 10^{-9} in future experiments, which would provide a highly sensitive test of the CPT symmetry using baryons.
Precise Determination of the Strangeness Magnetic Moment of the Nucleon
Leinweber, D B; Boinepalli, S; Cloet, I C; Thomas, A W; Williams, A G; Young, R D; Zanotti, J M; Zhang, J B
2005-06-01
By combining the constraints of charge symmetry with new chiral extrapolation techniques and recent low mass lattice QCD simulations of the individual quark contributions to the magnetic moments of the nucleon octet, we obtain a precise determination of the strange magnetic moment of the proton. The result, namely G{sub M}{sup s} = -0.051 +/- 0.021 mu{sub N}, is consistent with the latest experimental measurements but an order of magnitude more precise. This poses a tremendous challenge for future experiments.
Nuclear magnetic moments and related sum rules
Bentz, Wolfgang; Arima, Akito
2011-05-06
We first review the history and our present understanding of nuclear magnetic moments and Gamow-Teller transitions, with emphasis on the roles of configuration mixing and meson exchange currents. Then we discuss the renormalization of the orbital g-factor in nuclei, and its relation to the E1 sum rule for photoabsorption and the M1 sum rule for the scissors mode of deformed nuclei.
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.
Atomic Quadrupole Moment Measurement Using Dynamic Decoupling.
Shaniv, R; Akerman, N; Ozeri, R
2016-04-01
We present a method that uses dynamic decoupling of a multilevel quantum probe to distinguish small frequency shifts that depend on m_{j}^{2}, where m_{j}^{2} is the angular momentum of level |j⟩ along the quantization axis, from large noisy shifts that are linear in m_{j}, such as those due to magnetic field noise. Using this method we measured the electric-quadrupole moment of the 4D_{5/2} level in ^{88}Sr^{+} to be 2.973_{-0.033}^{+0.026}ea_{0}^{2}. Our measurement improves the uncertainty of this value by an order of magnitude and thus helps mitigate an important systematic uncertainty in ^{88}Sr^{+} based optical atomic clocks and verifies complicated many-body quantum calculations.
Atomic Quadrupole Moment Measurement Using Dynamic Decoupling.
Shaniv, R; Akerman, N; Ozeri, R
2016-04-01
We present a method that uses dynamic decoupling of a multilevel quantum probe to distinguish small frequency shifts that depend on m_{j}^{2}, where m_{j}^{2} is the angular momentum of level |j⟩ along the quantization axis, from large noisy shifts that are linear in m_{j}, such as those due to magnetic field noise. Using this method we measured the electric-quadrupole moment of the 4D_{5/2} level in ^{88}Sr^{+} to be 2.973_{-0.033}^{+0.026}ea_{0}^{2}. Our measurement improves the uncertainty of this value by an order of magnitude and thus helps mitigate an important systematic uncertainty in ^{88}Sr^{+} based optical atomic clocks and verifies complicated many-body quantum calculations. PMID:27104691
Porsev, S. G.; Ginges, J. S. M.; Flambaum, V. V.
2011-04-15
We have considered a mechanism for inducing a time-reversal violating electric dipole moment (EDM) in atoms through the interaction of a nuclear EDM d{sub N} with the hyperfine interaction, the ''magnetic moment effect''. We have derived the operator for this interaction and presented analytical formulas for the matrix elements between atomic states. Induced EDMs in the diamagnetic atoms {sup 129}Xe, {sup 171}Yb, {sup 199}Hg, {sup 211}Rn, and {sup 225}Ra have been calculated numerically. From the experimental limits on the atomic EDMs of {sup 129}Xe and {sup 199}Hg we have placed the following constraints on the nuclear EDMs, |d{sub N}({sup 129}Xe)|<1.1x10{sup -21}|e|cm and |d{sub N}({sup 199}Hg)|<2.8x10{sup -24}|e|cm.
Magnetic resonance signal moment determination using the Earth's magnetic field.
Fridjonsson, E O; Creber, S A; Vrouwenvelder, J S; Johns, M L
2015-03-01
We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.
Magnetic resonance signal moment determination using the Earth's magnetic field
NASA Astrophysics Data System (ADS)
Fridjonsson, E. O.; Creber, S. A.; Vrouwenvelder, J. S.; Johns, M. L.
2015-03-01
We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.
Magnetic resonance signal moment determination using the Earth's magnetic field.
Fridjonsson, E O; Creber, S A; Vrouwenvelder, J S; Johns, M L
2015-03-01
We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system. PMID:25700116
Constraining the neutrino magnetic dipole moment from white dwarf pulsations
Córsico, A.H.; Althaus, L.G.; García-Berro, E. E-mail: althaus@fcaglp.unlp.edu.ar E-mail: kepler@if.ufrgs.br
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.
Layer-Resolved Magnetic Moments in Ni/Pt Multilayers
NASA Astrophysics Data System (ADS)
Wilhelm, F.; Poulopoulos, P.; Ceballos, G.; Wende, H.; Baberschke, K.; Srivastava, P.; Benea, D.; Ebert, H.; Angelakeris, M.; Flevaris, N. K.; Niarchos, D.; Rogalev, A.; Brookes, N. B.
2000-07-01
The magnetic moments in Ni/Pt multilayers are thoroughly studied by combining experimental and ab initio theoretical techniques. SQUID magnetometry probes the samples' magnetizations. X-ray magnetic circular dichroism separates the contribution of Ni and Pt and provides a layer-resolved magnetic moment profile for the whole system. The results are compared to band-structure calculations. Induced Pt magnetic moments localized mostly at the interface are revealed. No magnetically ``dead'' Ni layers are found. The magnetization per Ni volume is slightly enhanced compared to bulk NiPt alloys.
Ground state magnetic dipole moment of {sup 35}K
Mertzimekis, T.J.; Mantica, P.F.; Liddick, S.N.; Tomlin, B.E.; Davies, A.D.
2006-02-15
The ground state magnetic moment of {sup 35}K has been measured using the technique of nuclear magnetic resonance on {beta}-emitting nuclei. The short-lived {sup 35}K nuclei were produced following the reaction of a {sup 36}Ar primary beam of energy 150 MeV/nucleon incident on a Be target. The spin polarization of the {sup 35}K nuclei produced at 2 deg. relative to the normal primary beam axis was confirmed. Together with the mirror nucleus {sup 35}S, the measurement represents the heaviest T=3/2 mirror pair for which the spin expectation value has been obtained. A linear behavior of g{sub p} vs g{sub n} has been demonstrated for the T=3/2 known mirror moments and the slope and intercept are consistent with the previous analysis of T=1/2 mirror pairs.
Top Quark Amplitudes with an Anomolous Magnetic Moment
Larkoski, Andrew J.; Peskin, Michael E.; /SLAC
2011-06-23
The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with t{bar t} and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.
Pinned orbital moments – A new contribution to magnetic anisotropy
NASA Astrophysics Data System (ADS)
Audehm, P.; Schmidt, M.; Brück, S.; Tietze, T.; Gräfe, J.; Macke, S.; Schütz, G.; Goering, E.
2016-05-01
Reduced dimensionality and symmetry breaking at interfaces lead to unusual local magnetic configurations, such as glassy behavior, frustration or increased anisotropy. The interface between a ferromagnet and an antiferromagnet is such an example for enhanced symmetry breaking. Here we present detailed X-ray magnetic circular dichroism and X-ray resonant magnetic reflectometry investigations on the spectroscopic nature of uncompensated pinned magnetic moments in the antiferromagnetic layer of a typical exchange bias system. Unexpectedly, the pinned moments exhibit nearly pure orbital moment character. This strong orbital pinning mechanism has not been observed so far and is not discussed in literature regarding any theory for local magnetocrystalline anisotropy energies in magnetic systems. To verify this new phenomenon we investigated the effect at different temperatures. We provide a simple model discussing the observed pure orbital moments, based on rotatable spin magnetic moments and pinned orbital moments on the same atom. This unexpected observation leads to a concept for a new type of anisotropy energy.
Measurement of electric dipole moments at storage rings
NASA Astrophysics Data System (ADS)
Jörg Pretz JEDI Collaboration
2015-11-01
The electric dipole moment (EDM) is a fundamental property of a particle, like mass, charge and magnetic moment. What makes this property in particular interesting is the fact that a fundamental particle can only acquire an EDM via {P} and {T} violating processes. EDM measurements contribute to the understanding of the matter over anti-matter dominance in the universe, a question closely related to the violation of fundamental symmetries. Up to now measurements of EDMs have concentrated on neutral particles. Charged particle EDMs can be measured at storage ring. Plans at Forschungszentrum Jülich and results of first test measurements at the COoler SYnchrotron COSY will be presented.
NASA Astrophysics Data System (ADS)
Illana Sisón, A.; Jungclaus, A.; Orlandi, R.; Perea, A.; Briz, J. A.; Bauer, C.; Gernhäuser, R.; Leske, J.; Mücher, D.; Pakarinen, J.; Pietralla, N.; Rajabali, M. M.; Seiler, D.; Stahl, C.
2014-03-01
The g factor of the first excited 2+ state of 72Zn has been measured using the Low Velocity Transient Field (LVTF) technique in combination with Coulomb excitation in inverse kinematics. The aim of the experiment was to test the viability of this method when applied to short-lived radioactive ISOL beams, in particular in comparison to the alternative High Velocity Transient Field (HVTF) technique using fragment beams. The result obtained for g(2+) in 72Zn in the present experiment follows the trend observed for the lighter stables Zn isotopes.
Tensor Charges, Quark Anomalous Magnetic Moments And Baryons
Mekhfi, M.
2007-06-13
We propose an 'ultimate' upgrade of the Karl- Sehgal (KS) formula which relates baryon magnetic moments to the spin structure of constituent quarks, by adding anomalous magnetic moments of quarks. We first argue that relativistic nature of quarks inside baryons requires introduction of two kinds of magnetisms, one axial and the other tensoriel. The first one is associated with integrated quark helicity distributions {delta}i - {delta}i-bar (standard ) and the second with integrated transversity distributions {delta}i - {delta}i-bar. The weight of each contribution is controlled by the combination of two parameters, xi the ratio of the quark mass to the average kinetic energy and ai the quark anomalous magnetic moment. The quark anomalous magnetic moment is thus shown to be correlated to transversity. The proposed formula confirms, with reasonable inputs that anomalous magnetic moments of quarks are unavoidable intrinsic properties.
Numerical modeling of higher order magnetic moments in UXO discrimination
Sanchez, V.; Yaoguo, L.; Nabighian, M.N.; Wright, D.L.
2008-01-01
The surface magnetic anomaly observed in unexploded ordnance (UXO) clearance is mainly dipolar, and consequently, the dipole is the only magnetic moment regularly recovered in UXO discrimination. The dipole moment contains information about the intensity of magnetization but lacks information about the shape of the target. In contrast, higher order moments, such as quadrupole and octupole, encode asymmetry properties of the magnetization distribution within the buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and to show its potential utility in UXO clearance, we present a numerical modeling study of UXO and related metallic objects. The tool for the modeling is a nonlinear integral equation describing magnetization within isolated compact objects of high susceptibility. A solution for magnetization distribution then allows us to compute the magnetic multipole moments of the object, analyze their relationships, and provide a depiction of the anomaly produced by different moments within the object. Our modeling results show the presence of significant higher order moments for more asymmetric objects, and the fields of these higher order moments are well above the noise level of magnetic gradient data. The contribution from higher order moments may provide a practical tool for improved UXO discrimination. ?? 2008 IEEE.
Weak magnetic moment on IrMn exchange bias pinning layers
Hase, T. P. A.; Fulthorpe, B. D.; Wilkins, S. B.; Tanner, B. K.; Marrows, C. H.; Hickey, B. J.
2001-08-13
We present evidence from soft x-ray resonant magnetic scattering measurements at the Mn L{sub 3} edge for the existence of a small magnetic moment on the antiferromagnetic IrMn pinning layer in a NiFe/Cu/Co/IrMn spin valve structure. The variation of the signal in an applied magnetic field shows that the moment lies antiparallel to the Co moment. Changes in the Mn L{sub 3} edge signal as the Co moment is rotated into the hard direction are rapid and do not appear to be associated with thermal reordering of the antiferromagnetic domain structure. {copyright} 2001 American Institute of Physics.
Ueno, Tetsuro; Sinha, Jaivardhan; Inami, Nobuhito; Takeichi, Yasuo; Mitani, Seiji; Ono, Kanta; Hayashi, Masamitsu
2015-01-01
We have studied the magnetic layer thickness dependence of the orbital magnetic moment in magnetic heterostructures to identify contributions from interfaces. Three different heterostructures, Ta/CoFeB/MgO, Pt/Co/AlOx and Pt/Co/Pt, which possess significant interface contribution to the perpendicular magnetic anisotropy, are studied as model systems. X-ray magnetic circular dichroism spectroscopy is used to evaluate the relative orbital moment, i.e. the ratio of the orbital to spin moments, of the magnetic elements constituting the heterostructures. We find that the relative orbital moment of Co in Pt/Co/Pt remains constant against its thickness whereas the moment increases with decreasing Co layer thickness for Pt/Co/AlOx, suggesting that a non-zero interface orbital moment exists for the latter system. For Ta/CoFeB/MgO, a non-zero interface orbital moment is found only for Fe. X-ray absorption spectra shows that a particular oxidized Co state in Pt/Co/AlOx, absent in other heterosturctures, may give rise to the interface orbital moment in this system. These results show element specific contributions to the interface orbital magnetic moments in ultrathin magnetic heterostructures. PMID:26456454
Numerical modeling of magnetic moments for UXO applications
Sanchez, V.; Li, Y.; Nabighian, M.; Wright, D.
2006-01-01
The surface magnetic anomaly observed in UXO clearance is mainly dipolar and, consequently, the dipole is the only magnetic moment regularly recovered in UXO applications. The dipole moment contains information about intensity of magnetization but lacks information about shape. In contrast, higher-order moments, such as quadrupole and octupole, encode asymmetry properties of the magnetization distribution within the buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and its potential utility in UXO clearance, we present a 3D numerical modeling study for highly susceptible metallic objects. The basis for the modeling is the solution of a nonlinear integral equation describing magnetization within isolated objects. A solution for magnetization distribution then allows us to compute magnetic moments of the object, analyze their relationships, and provide a depiction of the surface anomaly produced by different moments within the object. Our modeling results show significant high-order moments for more asymmetric objects situated at depths typical of UXO burial, and suggest that the increased relative contribution to magnetic gradient data from these higher-order moments may provide a practical tool for improved UXO discrimination.
Measurement of a weak transition moment using Coherent Control
NASA Astrophysics Data System (ADS)
Antypas, Dionysios
We have developed a two-pathway Coherent Control technique for measurements of weak optical transition moments. We demonstrate this technique through a measurement of the transition moment of the highly-forbidden magnetic dipole transition between the 6s2S 1/21/2 and 7s2S 1/21/2 states in atomic Cesium. The experimental principle is based on a two-pathway excitation, using two phase-coherent laser fields, a fundamental field at 1079 nm and its second harmonic at 539.5 nm. The IR field induces a strong two-photon transition, while the 539.5 nm field drives a pair of weak one-photon transitions: a Stark-induced transition of controllable strength as well as the magnetic dipole transition. Observations of the interference between these transitions for different Stark-induced transition amplitudes, allow a measurement of the ratio of the magnetic dipole to the Stark-induced moment. The interference between the transitions is controlled by modulation of the phase-delay between the two optical fields. Our determination of the magnetic dipole moment is at the 0.4% level and in good agreement with previous measurements, and serves as a benchmark for our technique and apparatus. We anticipate that with further improvement of the apparatus detection sensitivity, the demonstrated scheme can be used for measurements of the very weak Parity Violation transition moment on the Cesium 6s2 S1/2→7s2 S1/2 transition.
Magnetic moments of octet baryons and sea antiquark polarizations
Bartelski, Jan; Tatur, Stanislaw
2005-01-01
Using generalized Sehgal equations for magnetic moments of baryon octet and taking into account {sigma}{sup 0}-{lambda} mixing and two particle corrections to independent quark contributions we obtain very good fit using experimental values for errors of such moments. We present sum rules for quark magnetic moments ratios and for integrated spin densities ratios. Because of the SU(3) structure of our equations the results for magnetic moments of quarks and their densities depend on two additional parameters. Using information from deep inelastic scattering and baryon {beta}-decays we discuss the dependence of antiquark polarizations on introduced parameters. For some plausible values of these parameters we show that these polarizations are small if we neglect angular momenta of quarks. Our very good fit to magnetic moments of baryon octet can still be improved by using specific model for angular momentum of quarks.
Relative importance of magnetic moments in UXO clearance applications
Sanchez, V.; Li, Y.; Nabighian, M.; Wright, D.
2006-01-01
Surface magnetic anomaly observed in UXO clearance is mainly dipolar and, as a result, the dipole is the only moment used regularly in UXO applications. The dipole moment contains intensity of magnetization information but lacks shape information. Unlike dipole, higher-order moments, such as quadrupole and octupole, encode asymmetry properties of magnetization distribution within buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and its potential utility in UXO clearance, we present results of a 3D numerical modeling study for highly susceptible metallic objects. The basis for modeling is the solution of a nonlinear integral equation, describing magnetization within isolated objects, allowing us to compute magnetic moments of the object, analyze their relationships, and provide a depiction of the surface anomaly produced by the different moments within the object. Our modeling results show significant high-order moments for more asymmetric objects situated at typical UXO burial depths, and suggest that the increased relative contribution to magnetic gradient data from these higher-order moments may provide a practical tool for improved UXO discrimination. ?? 2005 Society of Exploration Geophysicists.
Anomalous magnetic moment of the muon in a dispersive approach
NASA Astrophysics Data System (ADS)
Pauk, Vladyslav; Vanderhaeghen, Marc
2014-12-01
We present a new general dispersive formalism for evaluating the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. In the suggested approach, this correction is related to the imaginary part of the muon's electromagnetic vertex function. The latter may be directly related to measurable hadronic processes by means of unitarity and analyticity. As a test we apply the introduced formalism to the case of meson pole exchanges and find agreement with the direct two-loop calculation.
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H. W.; Orginos, K.; Parreño, A.; Savage, M. J.; Tiburzi, B. C.
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and 3He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to mπ ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of 3He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures itsmore » dominant structure. Similarly a shell-model-like moment is found for the triton, μ3H ~ μp. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.« less
The Determination of the Muon Magnetic Moment from Cosmic Rays
ERIC Educational Resources Information Center
Amsler, C.
1974-01-01
Describes an experiment suited for use in an advanced laboratory course in particle physics. The magnetic moment of cosmic ray muons which have some polarization is determined with an error of about five percent. (Author/GS)
Magnetic moment softening and domain wall resistance in Ni nanowires.
Burton, J D; Sabirianov, R F; Jaswal, S S; Tsymbal, E Y; Mryasov, O N
2006-08-18
We perform ab initio calculations of the electronic structure and conductance of atomic-size Ni nanowires with domain walls only a few atomic lattice constants wide. We show that the hybridization between noncollinear spin states leads to a reduction of the magnetic moments in the domain wall resulting in the enhancement of the domain wall resistance. Experimental studies of the magnetic moment softening may be feasible with modern techniques such as scanning tunneling spectroscopy. PMID:17026271
Neutrino magnetic moment effects in neutrino nucleus reactions
Singh, S.K.; Athar, M.S.
1995-10-01
Some low energy neutrino nucleus reactions induced by neutrinos (antineutrinos) having a magnetic moment of the order of 10{sup {minus}9}{minus}10{sup {minus}10} Bohr magneton are studied. It is found that in the case of {sup 4}He, {sup 12}C, and {sup 16}O, the detection of very low energy scalar and isoscalar elastic and inelastic reactions induced by the isoscalar vector currents can provide a better limit on the neutrino magnetic moment.
Rabi, the proton magnetic moment, and the ‘2-wire' magnet, 1931-34
NASA Astrophysics Data System (ADS)
Forman, Paul
2001-04-01
With the assistance of Gregory Breit, I.I. Rabi, at Columbia University, worked out in 1931 a method to determine the spin (not the magnetic moment) of atomic nuclei by deflecting an atomic beam of the isotope in question in a weak, but long, inhomogeneous magnetic field. Crucial to this method was that it required no exact knowledge of that field. When the sensational result -- µp = 2.5µ_Bohr(m_e/m_p) -- from Otto Stern's deflection of a beam of hydrogen molecules in a strong magnetic field became known late in 1932, its confirmation by another laboratory, preferably by another method, seemed urgent. No one else had the refined technique to reproduce Stern's experiment. But because the hydrogen electronic wave function was known, the Breit-Rabi technique was susceptible of extension in this case to the measurement of the magnetic moment of the proton - - but only with accurate knowledge of the magnetic field and field gradient traversed by the atomic hydrogen beam. To this end Rabi introduced the '2-wire' magnet, producing a weak field and uniform gradient that could be calculated rather than measured. This field configuration quickly came to be used in all magnetic deflection experiments in Rabi's laboratory, first as produced directly by electric currents, and subsequently as emulated in iron electromagnets in order to achieve the higher magnetic fields required by molecular beam magnetic resonance experiments from 1937 onward.
Rabi, the proton magnetic moment, and the ¡2-wire¢ magnet, 1931-34
NASA Astrophysics Data System (ADS)
Forman, Paul
2001-04-01
With the assistance of Gregory Breit, I.I. Rabi, at Columbia University, worked out in 1931 a method to determine the spin (not the magnetic moment) of atomic nuclei by deflecting an atomic beam of the isotope in question in a weak, but long, inhomogeneous magnetic field. Crucial to this method was that it required no exact knowledge of that field. When the sensational result: p = 2.5:_Bohr(m_e/m_p) from Otto Stern's deflection of a beam of hydrogen molecules in a strong magnetic field became known late in 1932, its confirmation by another laboratory, preferably by another method, seemed urgent. No one else had the refined technique to reproduce Stern's experiment. But because the hydrogen electronic wave function was known, the Breit Rabi technique was susceptible of extension in this case to the measurement of the magnetic moment of the proton but only with accurate knowledge of the magnetic field and field gradient traversed by the atomic hydrogen beam. To this end Rabi introduced the '2 wire' magnet, producing a weak field and uniform gradient that could be calculated rather than measured. This field configuration quickly came to be used in all magnetic deflection experiments in Rabi's laboratory, first as produced directly by electric currents, and subsequently as emulated in iron electromagnets in order to achieve the higher magnetic fields required by molecular beam magnetic resonance experiments from 1937 onward.
Pinned orbital moments – A new contribution to magnetic anisotropy
Audehm, P.; Schmidt, M.; Brück, S.; Tietze, T.; Gräfe, J.; Macke, S.; Schütz, G.; Goering, E.
2016-01-01
Reduced dimensionality and symmetry breaking at interfaces lead to unusual local magnetic configurations, such as glassy behavior, frustration or increased anisotropy. The interface between a ferromagnet and an antiferromagnet is such an example for enhanced symmetry breaking. Here we present detailed X-ray magnetic circular dichroism and X-ray resonant magnetic reflectometry investigations on the spectroscopic nature of uncompensated pinned magnetic moments in the antiferromagnetic layer of a typical exchange bias system. Unexpectedly, the pinned moments exhibit nearly pure orbital moment character. This strong orbital pinning mechanism has not been observed so far and is not discussed in literature regarding any theory for local magnetocrystalline anisotropy energies in magnetic systems. To verify this new phenomenon we investigated the effect at different temperatures. We provide a simple model discussing the observed pure orbital moments, based on rotatable spin magnetic moments and pinned orbital moments on the same atom. This unexpected observation leads to a concept for a new type of anisotropy energy. PMID:27151436
Pinned orbital moments - A new contribution to magnetic anisotropy.
Audehm, P; Schmidt, M; Brück, S; Tietze, T; Gräfe, J; Macke, S; Schütz, G; Goering, E
2016-01-01
Reduced dimensionality and symmetry breaking at interfaces lead to unusual local magnetic configurations, such as glassy behavior, frustration or increased anisotropy. The interface between a ferromagnet and an antiferromagnet is such an example for enhanced symmetry breaking. Here we present detailed X-ray magnetic circular dichroism and X-ray resonant magnetic reflectometry investigations on the spectroscopic nature of uncompensated pinned magnetic moments in the antiferromagnetic layer of a typical exchange bias system. Unexpectedly, the pinned moments exhibit nearly pure orbital moment character. This strong orbital pinning mechanism has not been observed so far and is not discussed in literature regarding any theory for local magnetocrystalline anisotropy energies in magnetic systems. To verify this new phenomenon we investigated the effect at different temperatures. We provide a simple model discussing the observed pure orbital moments, based on rotatable spin magnetic moments and pinned orbital moments on the same atom. This unexpected observation leads to a concept for a new type of anisotropy energy. PMID:27151436
NASA Astrophysics Data System (ADS)
Zwarun, Andrew A.; Bourdillon, Antony J.; Button, Terry M.; Chaparali, Marali; Castro, Dan J.
1992-06-01
The embryonic area of interventional MRI, i.e. interstitial therapy under MR guidance, includes deep tissue laser ablation of lesions. Laser fibers can be located inside lesions by first inserting an MR-compatible cannula into the lesion and then inserting the laser fiber through the cannula into the lesion. Two factors are critical in selecting alloys for cannulae: the material should exhibit so little magnetic susceptibility that it will neither distort the MR image nor torque even at high field strengths, yet it should exhibit enough susceptibility defect that the cannula can be visualized by MR during positioning. Wires of metals and alloys were tested in a magnetometer to measure their magnetic moment, and imaged with spin echo and gradient echo MRI. Direct measurement of magnetic moment was a good indicator of MR- compatibility. Artifacts visualized with spin echo pulse sequences were smaller than those produced with gradient echo sequences.
Planar Hall ring sensor for ultra-low magnetic moment sensing
NASA Astrophysics Data System (ADS)
Hung, Tran Quang; Terki, Ferial; Kamara, Souleymanne; Kim, Kunwoo; Charar, Salam; Kim, CheolGi
2015-04-01
The field sensitivity of a planar Hall effect (PHE) micro-ring type biosensor has been investigated as a function of magnetizing angle of the sensor material, for the sensing of low magnetic moment superparamagnetic labels. The field sensitivity is maximal at a magnetizing angle of α = 20°. At this optimized magnetizing angle, the field sensitivity of a PHE sensor is about 3.6 times higher than that measured at the conventional configuration, α = 90°. This optimization enables the PHE-ring sensor to detect superparamagnetic biolabels with ultra-low magnetic moments down to 4 × 10-13 emu.
Quantum tunneling of the magnetic moment in the S/F/S Josephson φ0 junction
NASA Astrophysics Data System (ADS)
Chudnovsky, Eugene M.
2016-04-01
We show that the S/F/S Josephson φ0 junction permits detection of macroscopic quantum tunneling and quantum oscillation of the magnetic moment by measuring the ac voltage across the junction. Exact expression for the tunnel splitting renormalized by the interaction with the superconducting order parameter is obtained. It is demonstrated that magnetic tunneling may become frozen at a sufficiently large φ0. The quality factor of quantum oscillations of the magnetic moment due to finite ohmic resistance of the junction is computed. It is shown that magnetic tunneling rate in the φ0 junction can be controlled by the bias current, with no need for the magnetic field.
Electron Paramagnetic Resonance of Single Magnetic Moment on a Surface
Berggren, P.; Fransson, J.
2016-01-01
We address electron spin resonance of single magnetic moments in a tunnel junction using time-dependent electric fields and spin-polarized current. We show that the tunneling current directly depends on the local magnetic moment and that the frequency of the external electric field mixes with the characteristic Larmor frequency of the local spin. The importance of the spin-polarized current induced anisotropy fields acting on the local spin moment is, moreover, demonstrated. Our proposed model thus explains the absence of an electron spin resonance for a half integer spin, in contrast with the strong signal observed for an integer spin. PMID:27156935
Magnetic Moment Enhancement for Mn7 Cluster on Graphene
Liu, Xiaojie; Wang, Cai-Zhuang; Lin, Hai-Qing; Ho, Kai-Ming
2014-08-21
Mn7 cluster on graphene with different structural motifs and magnetic orders are investigated systematically by first-principles calculations. The calculations show that Mn7 on graphene prefers a two-layer motif and exhibits a ferrimagnetic coupling. The magnetic moment of the Mn7 cluster increases from 5.0 μB at its free-standing state to about 6.0 μB upon adsorption on graphene. Mn7 cluster also induces about 0.3 μB of magnetic moment in the graphene layer, leading to an overall enhancement of 1.3 μB magnetic moment for Mn7 on graphene. Detail electron transfer and bonding analysis have been carried out to investigate the origin of the magnetic enhancement.
Direct observation of depth profile of magnetic moment by magnetic circular dichroism
NASA Astrophysics Data System (ADS)
Mun, Bongjin Simon; Yang, See-Hun; Mannella, Norman; Kay, Alex W.; Kim, Sang-Koog; Kortright, Jeffrey B.; Underwood, Jim H.; Hussain, Zahid; Fadley, Charles S.
2001-03-01
The magnetic properties at the interface between Fe and Cr wedge layers are investigated with a new depth-resolved soft x-ray photoemission spectroscopy (SXPS)[1], combined with magnetic circular dichroism (MCD). The layers of Fe (10 A)/ Cr (50 A wedge- shaped) are grown on a periodic multilayer (B 4 C(22.5A)/W(17.1 A)) _40, which provides the strong standing wave effects of 40 The unique angular dependence of photoelectron intensity of Fe and Cr has been observed at each different Cr wedge thickness and show excellent agreement with the theoretical calculation. To maximize the enhancement and contrast of standing wave effect inside of sample, the sample position is tuned to the Bragg angle position, at which the MCD measurement with SXPS along the different thickness of Cr wedge layer provides the depth profile of the magnetic moment of Fe and Cr. A strong antiparallel coupling across the interface of Cr magnetic moment is clearly resolved while the apparent reduction of Fe magnetic moment is observed near the interface. This observation is consistent with the other works on the same system [2] and even describes how the magnetic moment behaves inside of the sample from the top surface to the interface in one single sample preparation. In this experiment, a new depth-resolved SXPS has been successfully implemented to magnetic multilayer system and prove to be powerful technique to study the buried interface of magnetic system, as proposed by our former work [1]. [1] S.-H. Yang, B. S. Mun, A.W. Kay, S.-K. Kim, J. B. Kortright , J.H. Underwood, Z. Hussain, C. S. Fadley, Surf. Sci. 461 L557-L564 (2000) [2] G. Panaccione, F. Sirotti, E. Narducci, and G. Rossi, Phys. Rev. B 55, 389 (1997)
Field-enhanced magnetic moment in ellipsoidal nano-hematite
NASA Astrophysics Data System (ADS)
Malik, Vikash; Sen, Somaditya; Gelting, David R.; Gajdardziska-Josifovska, Marija; Schmidt, Marius; Guptasarma, Prasenjit
2014-04-01
Bulk hematite is a canted antiferromagnet at room temperature and displays weak magnetic coercivity above the Morin transition temperature T M ˜ 262 K. Below T M, hematite displays traditional antiferromagnetic behavior, with no net magnetic moment or magnetic hysteresis. Here, we report that ellipsoidal nanocrystals of hematite (ENH) display a significant field-enhanced magnetic moment (FEMM) upon being poled by a magnetic field. This poled moment displays a giant coercive field of nearly 6000 Oe at low temperature. Atomic resolution transmission electron microscopy indicates that the nanocrystals are single crystalline, and that the surfaces are bulk-terminated. The apical terminations include the <001> sets of planes, which are implicated in possible formation of FM-arrangements near the surface. We tentatively suggest that FEMM in ENH could also arise from uncompensated surface spins or a shell of ordered spins oriented and pinned near the surface by a magnetic field. The gradual loss of magnetic moment with increasing temperature could arise as a result of competition between surface pinning energy, and kT. The large coercive field points toward possible applications for ENH in digital magnetic recording.
Preliminary studies for anapole moment measurements in rubidium and francium
NASA Astrophysics Data System (ADS)
Sheng, D.; Orozco, L. A.; Gomez, E.
2010-04-01
Preparations for the anapole measurement in Fr indicate the possibility of performing a similar measurement in a chain of Rb. The sensitivity analysis based on a single-nucleon model shows the potential for placing strong limits on the nucleon weak interaction parameters. There are values of the magnetic fields at much lower values than previously found that are insensitive to first-order changes in the field. The anapole moment effect in Rb corresponds to an equivalent electric field that is 80 times smaller than in Fr, but the stability of the isotopes and the current performance of the dipole trap in the apparatus presented here are encouraging for pursuing the measurement.
Magnetic moments induce strong phonon renormalization in FeSi
Krannich, S.; Sidis, Y.; Lamago, D.; Heid, R.; Mignot, J.-M.; Löhneysen, H. v.; Ivanov, A.; Steffens, P.; Keller, T.; Wang, L.; Goering, E.; Weber, F.
2015-01-01
The interactions of electronic, spin and lattice degrees of freedom in solids result in complex phase diagrams, new emergent phenomena and technical applications. While electron–phonon coupling is well understood, and interactions between spin and electronic excitations are intensely investigated, only little is known about the dynamic interactions between spin and lattice excitations. Noncentrosymmetric FeSi is known to undergo with increasing temperature a crossover from insulating to metallic behaviour with concomitant magnetic fluctuations, and exhibits strongly temperature-dependent phonon energies. Here we show by detailed inelastic neutron-scattering measurements and ab initio calculations that the phonon renormalization in FeSi is linked to its unconventional magnetic properties. Electronic states mediating conventional electron–phonon coupling are only activated in the presence of strong magnetic fluctuations. Furthermore, phonons entailing strongly varying Fe–Fe distances are damped via dynamic coupling to the temperature-induced magnetic moments, highlighting FeSi as a material with direct spin–phonon coupling and multiple interaction paths. PMID:26611619
Magnetic moments induce strong phonon renormalization in FeSi.
Krannich, S; Sidis, Y; Lamago, D; Heid, R; Mignot, J-M; Löhneysen, H v; Ivanov, A; Steffens, P; Keller, T; Wang, L; Goering, E; Weber, F
2015-01-01
The interactions of electronic, spin and lattice degrees of freedom in solids result in complex phase diagrams, new emergent phenomena and technical applications. While electron-phonon coupling is well understood, and interactions between spin and electronic excitations are intensely investigated, only little is known about the dynamic interactions between spin and lattice excitations. Noncentrosymmetric FeSi is known to undergo with increasing temperature a crossover from insulating to metallic behaviour with concomitant magnetic fluctuations, and exhibits strongly temperature-dependent phonon energies. Here we show by detailed inelastic neutron-scattering measurements and ab initio calculations that the phonon renormalization in FeSi is linked to its unconventional magnetic properties. Electronic states mediating conventional electron-phonon coupling are only activated in the presence of strong magnetic fluctuations. Furthermore, phonons entailing strongly varying Fe-Fe distances are damped via dynamic coupling to the temperature-induced magnetic moments, highlighting FeSi as a material with direct spin-phonon coupling and multiple interaction paths. PMID:26611619
Origin of the giant magnetic moment in epitaxial Fe3O4 thin films
NASA Astrophysics Data System (ADS)
Orna, J.; Algarabel, P. A.; Morellón, L.; Pardo, J. A.; de Teresa, J. M.; López Antón, R.; Bartolomé, F.; García, L. M.; Bartolomé, J.; Cezar, J. C.; Wildes, A.
2010-04-01
We study the enhanced magnetic moment observed in epitaxial magnetite (Fe3O4) ultrathin films (t<15nm) grown on MgO (001) substrates by means of pulsed laser deposition. The Fe3O4 (001) thin films exhibit high crystallinity, low roughness, and sharp interfaces with the substrate, and the existence of the Verwey transition at thicknesses down to 4 nm. The evolution of the Verwey transition temperature with film thickness shows a dependence with the antiphase boundaries density. Superconducting quantum interference device (SQUID) and vibrating sample magnetometry measurements in ultrathin films show a magnetic moment much higher than the bulk magnetite value. In order to study the origin of this anomalous magnetic moment, polarized neutron reflectivity (PNR), and x-ray magnetic circular dichroism (XMCD) experiments have been performed, indicating a decrease in the magnetization with decreasing sample thickness. X-ray photoemission spectroscopy measurements show no metallic Fe clusters present in the magnetite thin films. Through inductively coupled plasma mass spectroscopy and SQUID magnetometry measurements performed in commercial MgO (001) substrates, the presence of Fe impurities embedded within the substrates has been observed. Once the substrate contribution has been corrected, a decrease in the magnetic moment of magnetite thin films with decreasing thickness is found, in good agreement with the PNR and XMCD measurements. Our experiments suggest that the origin of the enhanced magnetic moment is not intrinsic to magnetite but due to the presence of Fe impurities in the MgO substrates.
Contributions to the muon's anomalous magnetic moment from a hidden sector
McKeen, David
2011-06-15
Research Highlights: > Described scenario involving hidden and connector particles that couple to the standard model which could be relevant for dark matter. > Examined constraints on such particles in the case that the SM particle they couple to is the muon. > Found regions of couplings which could explain the discrepancy in the muon's anomalous magnetic moment which differ for different hidden and connector particles' spins. - Abstract: The measurement of the anomalous magnetic moment of the muon provides a stringent test of the standard model and of any physics that lies beyond it. There is currently a deviation of 3.1{sigma} between the standard model prediction for the muon's anomalous magnetic moment and its experimental value. We calculate the contribution to the anomalous magnetic moment in theories where the muon couples to a particle in a hidden sector (that is, uncharged under the standard model) and a connector (which has nontrivial standard model gauge and hidden sector quantum numbers).
NASA Astrophysics Data System (ADS)
Lebedev, A. V.
2015-01-01
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.
Daugas, J. M.; Gaudefroy, L.; Meot, V.; Morel, P.; Rosse, B.; Hass, M.; Kumar, V.; Angelique, J. C.; Simpson, G. S.; Balabanski, D. L.; Fiori, E.; Georgiev, G.; Lozeva, R.; Force, C.; Grevy, S.; Stodel, Ch.; Thomas, J. C.; Kameda, D.; Matea, I.; Singh, B. S. Nara
2008-11-11
The gyromagnetic factor of the isomeric state of {sup 43}S has been measured using the Time Dependent Perturbed Angular Distribution (TDPAD) technique. The isomer was produced and spin aligned via the fragmentation of a 60 AMeV {sup 48}Ca beam at the GANIL facility. The deduced magnetic moment confirms the 7/2{sup -} spin/parity of the isomeric state and shows, for the first time, the intruder nature of the ground state. Comparison of the experimental values with Shell Model and mean-field based calculations were performed revealing a pronounced ground state deformation and a quasi-spherical isomeric state. A new isomeric state has been observed in the {sup 42}P.
Systematic study of hypernuclear magnetic moments under a perturb treatment
NASA Astrophysics Data System (ADS)
Wang, X. S.; Sang, H. Y.; Lü, H. F.; Yao, J. M.; Sagawa, H.
2013-08-01
Hypernuclei ranged from light to heavy mass are systematically investigated using a relativistic mean-field (RMF) model with a novel proposed ωΛΛ tensor coupling interaction PK1-Y1. The tensor coupling effect on core polarization, and the orbital contribution to hyperon current are discussed. Contributions to the magnetic moment from pΛ and n -1 Λ systems are found to be opposite. An expression of the magnetic moment under perturb treatment is improved with an ωΛΛ tensor coupling and the core-polarized magnetic moment μ {/D pol.} is found to be approximately proportional to the coupling strength g ωN · g {ωλ/2}. Self-consistent calculations under a perturb treatment show a semi-linear relationship as μ {/D pol.} ˜ g ωλ when g ωN is fixed.
Photoproduction of the rho meson and its magnetic moments
Kaneko, Hiromi; Hosaka, Atsushi; Scholten, Olaf
2011-10-21
We study photoproduction of {rho} meson in a model of hidden local symmetry. We introduce the {rho} meson on a hidden gauge boson and phenomenological {rho} meson-nucleon Lagrangian is constructed respecting chiral symmetry. It turns out that the {sigma}-exchange interaction plays an important role in neutral {rho} meson photoproduction to reproduce the experimental cross sections. In charged {rho} meson photoproduction, the model takes into account the {rho} meson magnetic moments from the three-point vertex in the kinetic terms. We show that the magnetic moment of the charged {rho} meson has a significant effect on the total cross sections in proportion to the photon energies.
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H. W.; Orginos, K.; Parreño, A.; Savage, M. J.; Tiburzi, B. C.
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and ^{3}He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m_{π} ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of ^{3}He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures its dominant structure. Similarly a shell-model-like moment is found for the triton, μ_{3H} ~ μ_{p}. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.
Anomalous Magnetic Moment of the W Boson in Different Models.
NASA Astrophysics Data System (ADS)
Couture, Gilles
We consider the anomalous magnetic moment of the W boson, kappa, from an experimental and from a theoretical point of view. In the first chapter, we consider five experiments where this parameter could in principle be measured. Our results show that the W pair-production remains the best process to measure kappa. Single W production is very sensitive to kappa, but it is plagued by very small cross-sections. Photon-electron colliders can also be valuable for measuring kappa through single W production. In the second chapter, we consider a composite model where kappa is essentially free. We found that it is impossible to rule out such a model from a single measurement of kappa. We give detailed production rates for these processes. In the second half of the thesis, we set limits on the corrections to kappa at the one loop level; first in the minimal SM and then in a two -Higgs-doublet model. The main results are that measured corrections of 0.1 would clearly indicate non-perturbative physics while the minimal SM can accommodate corrections up to 0.02. Possible extensions of the SM cannot increase this figure by much: unless one is willing to introduce several extra weakly interacting families, it remains that 75%, or more, of the corrections will arise from the minimal SM.
Object representation and magnetic moments in thin alkali films
NASA Astrophysics Data System (ADS)
Garrett, Douglas C.
2008-10-01
impurities 1/taus and their magnetic cross section sigmas are calculated. We find that single V surface impurities are magnetic while single Mo and Co impurities are non-magnetic. Co surface clusters are magnetic. In chapter 7, thin films of Na, K, Rb and Cs are quench condensed, then covered with 1/100 of a mono-layer of Ti and finally covered with the original host. The magnetization of the films is measured by means of the anomalous Hall effect. An anomalous Hall resistance RAHE is observed for Ti on the surface of K, Rb and Cs and for Ti inside of Cs. Essentially the RAHE varies linearly with the magnetic field and is inversely proportional to the inverse temperature. A small non-linearity of RAHE suggests a Ti moment of about 1microB.
Anomalous magnetic moment at Ba in Au
NASA Astrophysics Data System (ADS)
Bhati, A. K.; Kaur, J.; Bansal, N.; Negi, D.; Kumar, R.; Bhowmik, R. K.; Kumar, V.; Dey, C. C.
2015-04-01
The Time differential perturbed angular distribution (TDPAD) technique is employed to measure the local susceptibility at the recoil implanted Ba ions in Au following the nuclear reaction 120Sn(12C, 3nγ)129Ba. We have observed first time the local paramagnetic susceptibility of 5.26(18) at Ba ions comparable to 4f-ions in any non-ferromagnetic metal at room temperature which seems to be related to the electronic s-d and s-f transfer at positive lattice pressure.
Enhanced magnetic moment in ultrathin Fe-doped CoFe2O4 films
NASA Astrophysics Data System (ADS)
Moyer, J. A.; Vaz, C. A. F.; Kumah, D. P.; Arena, D. A.; Henrich, V. E.
2012-11-01
The effect of film thickness on the magnetic properties of ultrathin Fe-doped cobalt ferrite (Co1-xFe2+xO4) grown on MgO (001) substrates is investigated by superconducting quantum interference device magnetometry and x-ray magnetic linear dichroism, while the distribution of the Co2+ cations between the octahedral and tetrahedral lattice sites is studied with x-ray absorption spectroscopy. For films thinner than 10 nm, there is a large enhancement of the magnetic moment; conversely, the remanent magnetization and coercive fields both decrease, while the magnetic spin axes of all the cations become less aligned with the [001] crystal direction. In particular, at 300 K the coercive fields of the thinnest films vanish. The spectroscopy data show that no changes occur in the cation distribution as a function of film thickness, ruling this out as the origin of the enhanced magnetic moment. However, the magnetic measurements all support the possibility that these ultrathin Fe-doped CoFe2O4 films are transitioning into a superparamagnetic state, as has been seen in ultrathin Fe3O4. A weakening of the magnetic interactions at the antiphase boundaries, leading to magnetically independent domains within the film, could explain the enhanced magnetic moment in ultrathin Fe-doped CoFe2O4 and the onset of superparamagnetism at room temperature.
Nonadiabatic behavior of the magnetic moment of a charged particle in a dipole magnetic field
NASA Technical Reports Server (NTRS)
Murakami, Sadayoshi; Sato, Tetsuya; Hasegawa, Akira
1990-01-01
This paper investigates the dynamic behavior of the magnetic moment of a particle confined in a magnetic dipole field in the presence of a low-frequency electrostatic wave. It is shown that there exist two kinds of resonances (the bounce-E x B drift resonance and the wave-drift resonance) by which the adiabaticity of the magnetic moment is broken. The unstable conditions obtained by theoretical considerations showed good agreement with the numerical results.
Magnetic Moment Formation in Graphene Detected by Scattering of Pure Spin Currents
NASA Astrophysics Data System (ADS)
Swartz, Adrian; McCreary, Kathy; Chen, Jen-Ru; Han, Wei; Fabian, Jaroslav; Kawakami, Roland
2013-03-01
Graphene's 2D nature and high surface sensitivity have led to fascinating predictions for induced spin-based phenomena through careful control of adsorbates, including the extrinsic spin Hall effect, band gap opening, and induced magnetism. By taking advantage of atomic scale control provided by MBE, we have investigated deposition of adsorbates and their interactions with graphene. Spin transport measurements performed in-situ during systematic introduction of atomic hydrogen demonstrated that hydrogen adsorbed on graphene forms magnetic moments that couple via exchange to the injected spin current. The observed behavior is quantitatively explained utilizing a phenomenological theory for scattering of pure spin currents by localized magnetic moments. Lattice vacancies show similar behavior, indicating that the moments originate from so called pz-orbital defects. On the other hand, experiments with charge impurity scatterers such as Mg and Au, are noticeably absent of features related to magnetic moment formation. Furthermore, we observe gate dependent effective exchange fields due to the spin-spin coupling between conduction electrons and magnetic moments, which are of interest for novel phenomena and spintronic functionality but have not been seen previously in graphene.
Magnetic moments and non-Fermi-liquid behavior in quasicrystals
NASA Astrophysics Data System (ADS)
Andrade, Eric
Motivated by the intrinsic non-Fermi-liquid behavior observed in the heavy-fermion quasicrystal Au51Al34Yb15, we study the low-temperature behavior of dilute magnetic impurities placed in metallic quasicrystals. We find that a large fraction of the magnetic moments are not quenched down to very low temperatures, leading to a power-law distribution of Kondo temperatures, accompanied by a non-Fermi-liquid behavior, in a remarkable similarity to the Kondo-disorder scenario found in disordered heavy-fermion metals. This work was supported by FAPESP (Brazil) Grant No. 2013/00681-8.
General magnetic transition dipole moments for electron paramagnetic resonance.
Nehrkorn, Joscha; Schnegg, Alexander; Holldack, Karsten; Stoll, Stefan
2015-01-01
We present general expressions for the magnetic transition rates in electron paramagnetic resonance (EPR) experiments of anisotropic spin systems in the solid state. The expressions apply to general spin centers and arbitrary excitation geometry (Voigt, Faraday, and intermediate). They work for linear and circular polarized as well as unpolarized excitation, and for crystals and powders. The expressions are based on the concept of the (complex) magnetic transition dipole moment vector. Using the new theory, we determine the parities of ground and excited spin states of high-spin (S=5/2) Fe(III) in hemin from the polarization dependence of experimental EPR line intensities.
Progress towards an electron electric dipole moment measurement with laser-cooled atoms
NASA Astrophysics Data System (ADS)
Solmeyer, Neal
This dissertation recounts the progress made towards a measurement of the electron electric dipole moment. The existence of a permanent electric dipole moment of any fundamental particle would imply that both time reversal and parity invariance are violated. If an electric dipole moment were measured within current experimental limits it would be the first direct evidence for physics beyond the standard model. For our measurement we use laser-cooled alkali atoms trapped in a pair of 1D optical lattices. The lattices run through three electric field plates so that the two groups of atoms see opposing electric fields. The measurement chamber is surrounded by a four layer mu-metal magnetic shield. Under electric field quantization, the atoms are prepared in a superposition of magnetic sublevels that is sensitive to the electron electric dipole moment in Ramsey-like spectroscopy. The experiment requires very large electric fields and very small magnetic fields. Engineering a system compatible with both of these goals simultaneously is not trivial. Searches for electric dipole moments using neutral atoms in optical lattices have much longer possible interaction times and potentially give more precise information about the inherent symmetry breaking than other methods. This comes at the cost of a higher sensitivity to magnetic fields and possible sources of error associated with the trapping light. If noise and systematic errors can be controlled to our design specifications our experiment will significantly improve the current experimental limit of the electron electric dipole moment.
Magnetic moments and angular momenta of stars and planets
NASA Technical Reports Server (NTRS)
Arge, C. N.; Mullan, D. J.; Dolginov, A. Z.
1995-01-01
Using published data on magnetic fields, radii, masses, and rotation, we have compiled a data set of magnetic moments mu and angular momenta L for stars and planets. In our subsample of hotter stars (classes A, B, and O), there are 171 objects. In the subsample of cooler stars (classes F, G, K, and M), there are 54 objects. We include 33 white dwarfs, of which 19 are in cataclysmic variables. The pulsar subsample contains 32 pulsars in binaries and 429 isolated pulsars. Som subsamples exhibit significant empirical correlations between log mu and log L. For the hot and cool stars, the correlations are positive. However, the hot-star correlation is significantly shallower than for the cool stars. In the solar system subsample, the correlation has essentially the same slope as for the cool stars, although the magnetic moments are two to three orders of magnitude smaller for the solar system objects at a given L value. For isolated white dwarfs, the correlations are weak or absent. Pulsars and white dwarfs in close binaries show strong negative correlations: the results are quantitatively consistent with magnetically enforced synchronism with the orbital period. When we consider the centers of gravity of the different subsamples of objects, a significant positive correlation appears between log mu and log L.
Gravitational effects on measurements of the muon dipole moments
NASA Astrophysics Data System (ADS)
Kobach, Andrew
2016-10-01
If the technology for muon storage rings one day permits sensitivity to precession at the order of 10-8 Hz, the local gravitational field of Earth can be a dominant contribution to the precession of the muon, which, if ignored, can fake the signal for a nonzero muon electric dipole moment (EDM). Specifically, the effects of Earth's gravity on the motion of a muon's spin is indistinguishable from it having a nonzero EDM of magnitude dμ ∼10-29 ecm in a storage ring with vertical magnetic field of ∼ 1 T, which is significantly larger than the expected upper limit in the Standard Model, dμ ≲10-36 ecm. As a corollary, measurements of Earth's local gravitational field using stored muons would be a unique test to distinguish classical gravity from general relativity with a bonafide quantum mechanical entity, i.e., an elementary particle's spin.
Large transition magnetic moment of the neutrino from horizontal symmetry
NASA Astrophysics Data System (ADS)
Babu, K. S.; Mohapatra, Rabindra N.
1990-12-01
The apparent anticorrelation of the solar-neutrino signal with the 11-yr sunspot cycle observed by Davis can be understood if the electron neutrino has a large magnetic moment. We discuss extensions of the standard model, where the existence of a leptonic SU(2)H-horizontal symmetry between the electron and muon generations provides a way to understand such a large magnetic moment, while keeping the neutrino mass naturally small. A global le-lμ symmetry (li=ith lepton number) is maintained even after spontaneous gauge symmetry breaking, so that the neutrino is of Zeldovich-Konopinski-Mahmoud type with m2νe-m2νμ=0. This condition automatically guarantees that the neutrino spin precession in the magnetic field of the Sun is not suppressed. Of the two extensions of the standard model that we discuss, the first one is a local SU(2)H model with the horizontal symmetry broken completely at a TeV scale. We show how a global U(1)le-lμ can be maintained although le-lμ is a subgroup of the gauged SU(2)H. The second example is the minimal supersymmetric extension of the standard model with R-parity-violating [but (le-lμ)-conserving] interactions. An approximate SU(2)H symmetry between the e-μ families is imposed in order to suppress the neutrino mass, but not its magnetic moment. We provide a detailed theoretical and phenomenological investigation of these two models and discuss their tests at the colliders as well as in low-energy experiments. The models generally predict mνe~=1-10 eV and the existence of charged scalar particles in the mass range of 100 GeV.
Nucleon-nucleon bremsstrahlung: Anomalous magnetic moment effects
Timmermans, R.G.E.; Penninga, T.D.; Gibson, B.F.; Liou, M.K.
2006-03-15
Background: Two soft-photon amplitudes, the two-u-two-t special (TuTts) amplitude and the Low amplitude, are known to produce quantitatively similar np{gamma} cross sections, but they predict quite different pp{gamma} cross sections for those kinematic conditions in which the nucleon scattering angles are small (less than 25 deg.). Purpose: These two amplitudes have been applied to systematically investigate three different nucleon-nucleon bremsstrahlung (NN{gamma}) processes: pp{gamma},np{gamma}, and nn{gamma}. The nn{gamma} process is explored for the first time. The primary focus of this work is to investigate the contribution of the proton and the neutron anomalous magnetic moments to all three NN{gamma} processes for projectile energies above 150 MeV and for laboratory scattering angles ({theta}{sub 1} and {theta}{sub 2}) lying between 8 deg. and 40 deg.. Method: A special soft-photon expansion in which the TuTts amplitude is expanded in terms of the Low amplitude plus additional amplitudes is utilized to explore the relationship between the TuTts and Low amplitudes and the reasons why they agree and disagree. We also used the TuTts amplitude to calculate the NN{gamma} cross section with and without the anomalous magnetic moment contributions to explore the importance of that element of the electromagnetic current. Results: The TuTts amplitude describes well the available pp{gamma} cross-section data. The anomalous magnetic moment contribution is (i) significant in the pp{gamma} process when each scattering angle is less than 25 deg. but insignificant when each scattering angle is 40 deg. or greater and (ii) insignificant in the np{gamma} process for all scattering angles. The nn{gamma} cross sections for the TuTts and Low amplitudes differ substantially for the kinematics investigated. Conclusions: In general, the Low amplitude agrees well with the TuTts amplitude when anomalous magnetic moment effects are not significant, but the two amplitudes can yield
A planar triangular Dy3 + Dy3 single-molecule magnet with a toroidal magnetic moment.
Li, Xiao-Lei; Wu, Jianfeng; Tang, Jinkui; Le Guennic, Boris; Shi, Wei; Cheng, Peng
2016-07-21
A unique Dy6 complex with a planar Dy3 + Dy3 structure was assembled by delicately modifying the axial ligands. Single-molecule magnet behavior and meanwhile a toroidal magnetic moment in the ground state have been observed. PMID:27388113
(129) Xe and (131) Xe nuclear magnetic dipole moments from gas phase NMR spectra.
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 .
Magnetic moments of octet baryons, angular momenta of quarks, and sea antiquark polarizations
Bartelski, Jan; Tatur, Stanislaw
2010-03-01
One can determine antiquark polarizations in a proton using the information from deep inelastic scattering, {beta} decays of baryons, orbital angular momenta of quarks, as well as their integrated magnetic distributions. The last quantities were determined previously by us performing a fit to magnetic moments of a baryon octet. However, because of the SU(3) symmetry our results depend on two parameters. The quantity {Gamma}{sub V}, measured recently in a COMPASS experiment, gives the relation between these parameters. We can fix the last unknown parameter using the ratio of up and down quark magnetic moments which one can get from the fit to radiative vector meson decays. We calculate antiquark polarizations with the orbital momenta of valence quarks that follow from lattice calculations. The value of the difference of up and down antiquark polarizations obtained in our calculations is consistent with the result obtained in a HERMES experiment.
Magnetic structure of Yb2Pt2Pb: Ising moments on the Shastry-Sutherland lattice
Miiller, W.; Zaliznyak, I.; Wu, L. S.; Kim, M. S.; Orvis, T.; Simonson, J. W.; Gamza, M.; McNally, D. M.; Nelson, C. S.; Ehlers, G.; et al
2016-03-22
Neutron diffraction measurements were carried out on single crystals and powders of Yb2Pt2Pb, where Yb moments form two interpenetrating planar sublattices of orthogonal dimers, a geometry known as Shastry-Sutherland lattice, and are stacked along the c axis in a ladder geometry. Yb2Pt2Pb orders antiferromagnetically at TN=2.07K, and the magnetic structure determined from these measurements features the interleaving of two orthogonal sublattices into a 5×5×1 magnetic supercell that is based on stripes with moments perpendicular to the dimer bonds, which are along (110) and (–110). Magnetic fields applied along (110) or (–110) suppress the antiferromagnetic peaks from an individual sublattice, butmore » leave the orthogonal sublattice unaffected, evidence for the Ising character of the Yb moments in Yb2Pt2Pb that is supported by point charge calculations. Furthermore, specific heat, magnetic susceptibility, and electrical resistivity measurements concur with neutron elastic scattering results that the longitudinal critical fluctuations are gapped with ΔE≃0.07meV.« less
Atomic moments in Mn2CoAl thin films analyzed by X-ray magnetic circular dichroism
Jamer, M. E.; Assaf, B. A.; Sterbinsky, G. E.; Arena, D. A.; Heiman, D.
2014-12-05
Spin gapless semiconductors are known to be strongly affected by structural disorder when grown epitaxially as thin films. The magnetic properties of Mn2CoAl thin films grown on GaAs (001) substrates are investigated here as a function of annealing. This study investigates the atomic-specific magnetic moments of Mn and Co atoms measured through X-ray magnetic circular dichroism as a function of annealing and the consequent structural ordering. Results indicate that the structural distortion mainly affects the Mn atoms as seen by the reduction of the magnetic moment from its predicted value.
Measurement of an atomic quadrupole moment using dynamic decoupling
NASA Astrophysics Data System (ADS)
Akerman, Nitzan; Shaniv, Ravid; Ozeri, Roee
2016-05-01
Some of the best clocks today are ion-based optical clocks. These clocks are referenced to a narrow optical transition in a trapped ion. An example for such a narrow transition is the electric quadrupole E 2 transition between states with identical parity. An important systematic shift of such a transition is the quadrupole shift resulting from the electric field gradient inherent to the ion trap. We present a new dynamic decoupling method that rejects magnetic field noise while measuring the small quadrupole shift of the optical clock transition. Using our sequence we measured the quadrupole moment of the 4D5/2 level in a trapped 88 Sr+ ion to be 2 .973-0 . 033 + 0 . 026 ea02 , where e is the electron charge and a0 is the Bohr radius. Our measurement improves the uncertainty of this value by an order of magnitude and thus helps mitigate an important systematic uncertainty in 88 Sr+ based optical atomic clocks and verifies complicated many-body quantum calculations.
Evidence of Charge Transfer and Orbital Magnetic Moment in Multiferroic CuFeO2
NASA Astrophysics Data System (ADS)
Narumi, Yasuo; Nakamura, Tetsuya; Ikeno, Hidekazu; Terada, Noriki; Morioka, Takayuki; Saito, Kota; Kitazawa, Hideaki; Kindo, Koichi; Nojiri, Hiroyuki
2016-11-01
Soft X-ray absorption spectra (XAS) and magnetic circular dichroism (XMCD) of Fe and Cu L2,3 edges have been measured on the triangular lattice antiferromagnet CuFeO2. By applying sum rule analysis to the XMCD of Fe, the ratio of the orbital to spin magnetic moments is determined to be -0.071. Because the nominal valence of Fe in CuFeO2 was Fe3+ (3d5), the orbital magnetic moment was considered to be zero in the past. However, the present research demonstrates that the orbital magnetic moment of Fe takes a finite value and it is possibly due to Fe4+ (3d4), which is considered to be responsible for the strong magnetic anisotropy and the ferroelectricity. We compare the experimental results with the results of ab initio multiplet calculations based on the configuration interaction theory and discuss the anomalous electronic structures of Fe and Cu ions in CuFeO2.
Nuclear Magnetic Moment of {sup 210}Fr: A Combined Theoretical and Experimental Approach
Gomez, E.; Aubin, S.; Sprouse, G. D.; Orozco, L. A.; Iskrenova-Tchoukova, E.; Safronova, M. S.
2008-05-02
We measure the hyperfine splitting of the 9S{sub 1/2} level of {sup 210}Fr, and find a magnetic dipole hyperfine constant A=622.25(36) MHz. The theoretical value, obtained using the relativistic all-order method from the electronic wave function at the nucleus, allows us to extract a nuclear magnetic moment of 4.38(5){mu}{sub N} for this isotope, which represents a factor of 2 improvement in precision over previous measurements. The same method can be applied to other rare isotopes and elements.
Medium effects of magnetic moments of baryons on neutron stars under strong magnetic fields
Ryu, C. Y.; Cheoun, Myung-Ki; Kim, K. S.
2010-08-15
We investigate medium effects caused by density-dependent magnetic moments of baryons on neutron stars under strong magnetic fields. If we allow the variation of anomalous magnetic moments (AMMs) of baryons in dense matter under strong magnetic fields, AMMs of nucleons are enhanced to be larger than those of hyperons. The enhancement naturally causes the chemical potentials of the baryons to be large and leads to the increase of the proton fraction. Consequently, it causes the suppression of hyperons, resulting in stiffness of the equation of state. Under the presumed strong magnetic fields, we evaluate the relevant particle populations, the equation of state, and the maximum masses of neutron stars by including density-dependent AMMs and compare them with those obtained from AMMs in free space.
Instrument for measuring moment of inertia with high precision
NASA Astrophysics Data System (ADS)
Zheng, Yongjun; Lin, Min; Guo, Bin
2010-08-01
Accurate calculation of the moment of inertia of an irregular body is made difficult by the large number of quantities. A popular method is to use a trifilar suspension system to measure the period of oscillation of the body in the horizontal plane. In this paper, an instrument for measuring the moment of inertia based on trifilar pendulum is designed; some sources of error are discussed; three metal disks with known moments of inertia are used to calibrate the instrument, the other metal disks with known moments of inertia are used to test the accuracy of the instrument. The results are consistent when compared with calculated moment of inertia of the metal disks. In addition, the instrument could be used to measure the moment of inertia of other irregular objects. The period of oscillation is acquired by the capture mode of MSP430 microprocessor, the mass is obtained by the Electronic Balance and the data is transferred to the MSP430 via serial port.
Decoherence-governed magnetic-moment dynamics of supported atomic objects
NASA Astrophysics Data System (ADS)
Gauyacq, Jean-Pierre; Lorente, Nicolás
2015-11-01
Due to the quantum evolution of molecular magnetic moments, the magnetic state of nanomagnets can suffer spontaneous changes. This process can be completely quenched by environment-induced decoherence. However, we show that for typical small supported atomic objects, the substrate-induced decoherence does change the magnetic-moment evolution but does not quell it. To be specific and to compare with experiment, we analyze the spontaneous switching between two equivalent magnetization states of atomic structures formed by Fe on Cu2N/Cu (1 0 0), measured by Loth et al (2012 Science 335 196-9). Due to the substrate-induced decoherence, the Rabi oscillations proper to quantum tunneling between magnetic states are replaced by an irreversible decay of long characteristic times leading to the observed stochastic magnetization switching. We show that the corresponding switching rates are small, rapidly decreasing with system’s size, with a 1/T thermal behavior and in good agreement with experiments. Quantum tunneling is recovered as the switching mechanism at extremely low temperatures below the μK range for a six-Fe-atom system and exponentially lower for larger atomic systems. The unexpected conclusion of this work is that experiments could detect the switching of these supported atomic systems because their magnetization evolution is somewhere between complete decoherence-induced stability and unobservably fast quantum-tunneling switching.
Decoherence-governed magnetic-moment dynamics of supported atomic objects.
Gauyacq, Jean-Pierre; Lorente, Nicolás
2015-11-18
Due to the quantum evolution of molecular magnetic moments, the magnetic state of nanomagnets can suffer spontaneous changes. This process can be completely quenched by environment-induced decoherence. However, we show that for typical small supported atomic objects, the substrate-induced decoherence does change the magnetic-moment evolution but does not quell it. To be specific and to compare with experiment, we analyze the spontaneous switching between two equivalent magnetization states of atomic structures formed by Fe on Cu2N/Cu (1 0 0), measured by Loth et al (2012 Science 335 196-9). Due to the substrate-induced decoherence, the Rabi oscillations proper to quantum tunneling between magnetic states are replaced by an irreversible decay of long characteristic times leading to the observed stochastic magnetization switching. We show that the corresponding switching rates are small, rapidly decreasing with system's size, with a 1/T thermal behavior and in good agreement with experiments. Quantum tunneling is recovered as the switching mechanism at extremely low temperatures below the μK range for a six-Fe-atom system and exponentially lower for larger atomic systems. The unexpected conclusion of this work is that experiments could detect the switching of these supported atomic systems because their magnetization evolution is somewhere between complete decoherence-induced stability and unobservably fast quantum-tunneling switching. PMID:26471260
Probing neutrino magnetic moments at the Spallation Neutron Source facility
NASA Astrophysics Data System (ADS)
Kosmas, T. S.; Miranda, O. G.; Papoulias, D. K.; Tórtola, M.; Valle, J. W. F.
2015-07-01
Majorana neutrino electromagnetic properties are studied through neutral current coherent neutrino-nucleus scattering. We focus on the potential of the recently planned COHERENT experiment at the Spallation Neutron Source to probe muon-neutrino magnetic moments. The resulting sensitivities are determined on the basis of a χ2 analysis employing realistic nuclear structure calculations in the context of the quasiparticle random phase approximation. We find that they can improve existing limits by half an order of magnitude. In addition, we show that these facilities allow for standard model precision tests in the low energy regime, with a competitive determination of the weak mixing angle. Finally, they also offer the capability to probe other electromagnetic neutrino properties, such as the neutrino charge radius. We illustrate our results for various choices of experimental setup and target material.
Analyzing power in pion-proton bremsstrahlung, and the. Delta. sup ++ (1232) magnetic moment
Bosshard, A.; Amsler, C.; Doebeli, M.; Doser, M.; Schaad, M.; Riedlberger, J.; Truoel, P. ); Bistirlich, J.A.; Crowe, K.M.; Ljungfelt, S.; Meyer, C.A. ); van den Brandt, B.; Konter, J.A.; Mango, S.; Renker, D. ); Loude, J.F.; Perroud, J.P. ); Haddock, R.P. ); Sober, D.I. )
1991-10-01
We report on a first measurement of the polarized-target asymmetry of the pion-proton bremsstrahlung cross section ({pi}{sup +}{ital p}{r arrow}{pi}{sup {minus}}{ital p}{gamma}). As in previous cross section measurements the pion energy (298 MeV) and the detector geometry for this experiment was chosen to optimize the sensitivity to the radiation from the magnetic dipole moment of the {Delta}{sup ++}(1232) resonance {mu}{sub {Delta}}. Comparison to a recent isobar model for pion-nucleon bremsstrahlung yields {mu}{sub {Delta}}=(1.62{plus minus}0.18){mu}{sub {ital p}}, where {mu}{sub {ital p}} is the proton magnetic moment. Since the asymmetry depends less than the cross section on the choice of the other input parameters for the model, their uncertainties affect this analysis by less than the experimental error. However the theory fails to represent both the cross section and the asymmetry data at the highest photon energies. Hence further improvements in the calculations are needed before the model dependence of the magnetic moment analysis can be fully assessed. The present result agrees with bag-model corrections to the SU(6) prediction {mu}{sub {Delta}}=2{mu}{sub {ital p}}. As a by-product, the analyzing power for elastic {pi}{sup +}{ital p} scattering at 415 MeV/{ital c} was also measured. This second result is in good agreement with phase shift calculations.
Measurements of DSD Second Moment Based on Laser Extinction
NASA Technical Reports Server (NTRS)
Lane, John E.; Jones, Linwood; Kasparis, Takis C.; Metzger, Philip
2013-01-01
Using a technique recently developed for estimating the density of surface dust dispersed during a rocket landing, measuring the extinction of a laser passing through rain (or dust in the rocket case) yields an estimate of the 2nd moment of the particle cloud, and rainfall drop size distribution (DSD) in the terrestrial meteorological case. With the exception of disdrometers, instruments that measure rainfall make in direct measurements of the DSD. Most common of these instruments are the rainfall rate gauge measuring the 1 1/3 th moment, (when using a D(exp 2/3) dependency on terminal velocity). Instruments that scatter microwaves off of hydrometeors, such as the WSR-880, vertical wind profilers, and microwave disdrometers, measure the 6th moment of the DSD. By projecting a laser onto a target, changes in brightness of the laser spot against the target background during rain, yield a measurement of the DSD 2nd moment, using the Beer-Lambert law. In order to detect the laser attenuation within the 8-bit resolution of most camera image arrays, a minimum path length is required, depending on the intensity of the rainfall rate. For moderate to heavy rainfall, a laser path length of 100 m is sufficient to measure variations in optical extinction using a digital camera. A photo-detector could replace the camera, for automated installations. In order to spatially correlate the 2nd moment measurements to a collocated disdrometer or tipping bucket, the laser's beam path can be reflected multiple times using mirrors to restrict the spatial extent of the measurement. In cases where a disdrometer is not available, complete DSD estimates can be produced by parametric fitting of DSD model to the 2nd moment data in conjunction with tipping bucket data. In cases where a disdrometer is collocated, the laser extinction technique may yield a significant improvement to insitu disdrometer validation and calibration strategies
Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head.
Tao, Y; Eichler, A; Holzherr, T; Degen, C L
2016-01-01
Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz(-1/2), equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 10(6) T m(-1) and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ∼10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics. PMID:27647039
Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head
Tao, Y.; Eichler, A.; Holzherr, T.; Degen, C. L.
2016-01-01
Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz−1/2, equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 106 T m−1 and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ∼10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics. PMID:27647039
Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head
NASA Astrophysics Data System (ADS)
Tao, Y.; Eichler, A.; Holzherr, T.; Degen, C. L.
2016-09-01
Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz-1/2, equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 106 T m-1 and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ~10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics.
Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head.
Tao, Y; Eichler, A; Holzherr, T; Degen, C L
2016-09-20
Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz(-1/2), equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 10(6) T m(-1) and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ∼10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics.
Three-body recombination for electrons in a strong magnetic field: Magnetic moment
Robicheaux, F.
2006-03-15
Using a classical Monte Carlo method, we have computed the three-body recombination (two free electrons and a proton scattering into one free electron and a hydrogen atom, e+e+p{yields}H+e) in strong magnetic fields. The proton is fixed in space but the electrons are allowed their full, three-dimensional motion. We investigate recombination for temperatures and fields similar to those used in recent experiments that generated antihydrogen. The present rate is compared to that when the electrons' motion is given by the guiding center approximation, validating previous results at low temperature and demonstrating the breakdown of this approximation at higher temperature. Unlike the B=0 case, strong B gives preferential recombination to atoms with positive magnetic moment. Also, the canonical angular momentum in the field direction is often negative even when the magnetic moment is negative. Both results affect the trapping of antihydrogen using spatially dependent magnetic fields.
Probing the Pu4 + magnetic moment in PuF4 with 19F NMR spectroscopy
NASA Astrophysics Data System (ADS)
Capan, Cigdem; Dempsey, Richard J.; Sinkov, Sergey; McNamara, Bruce K.; Cho, Herman
2016-06-01
The magnetic fields produced by Pu4 + centers have been measured by 19F NMR spectroscopy to elucidate the Pu-F electronic interactions in polycrystalline PuF4. Spectra acquired at applied fields of 2.35 and 7.05 T reveal a linear scaling of the 19F line shape. A model is presented that treats the line broadening and shifts as due to dipolar fields produced by Pu valence electrons in localized noninteracting orbitals. Alternative explanations for the observed line shape involving covalent Pu-F bonding, superexchange interactions, and electronic configurations with enhanced magnetic moments are considered.
-Interface effects on the magnetic moment of Co and Cu in CoCu granular alloys
Garcia Prieto, A.; Fdez-Gubieda, M.L.; Chaboy, J.; Laguna-Marco, M.A.; Muro, T.; Nakamura, T.
2005-12-01
We report on x-ray magnetic circular dichroism experiments performed on Co{sub 5}Cu{sub 95} annealed granular alloys with giant magnetoresistance. Results on the Co-L{sub 2,3} edge evidence a direct correlation between the Co orbital and spin magnetic moment and the Co clusters interfacial roughness. On the other hand, we have found dichroism on the Cu-L{sub 2,3} edge, revealing an induced magnetic polarization of the Cu interfacial atoms. The magnetic moment of the Cu atoms is mainly of spin character and is ferromagnetically coupled with the Co magnetic moment.
Progress on the measurement of the francium anapole moment
NASA Astrophysics Data System (ADS)
Sheng, Dong; Hood, Jonathan; Lynam, Steven; Orozco, Luis; Gomez, Eduardo; Aubin, Seth; Gwinner, Gerald; Behr, John; Pearson, Matthew; Jackson, Peter; Melconian, Dan; Flambaum, Victor; Sprouse, Gene
2010-03-01
We present the current status of the experimental effort towards the measurement of the anapole moment in francium. The anapole is a parity violating, time-reversal conserving nuclear moment that arises from the weak interaction among nucleons. The anapole moment is nuclear spin dependent (nsd) and sensitive to the configuration of nuclear structure. Our experimental scheme is to perform a direct measurement of the nsd parity violation, by driving a parity forbidden E1 transition between hyperfine ground states in a series of francium isotopes inside a blue detuned dipole trap at the electric anti-node of a microwave cavity. We explore theoretical aspects and experimental requirements on the possible tests using rubidium isotopes. The experiment will be at the ISAC radioactive beam facility of TRIUMF. Work supported by NSF and DOE USA, NSERC and NRC Canada, CONACYT Mexico.
New Experiment to Measure the Electron Electric Dipole Moment
NASA Technical Reports Server (NTRS)
Kittle, Melanie
2003-01-01
An electron can possess an electric dipole moment (edm) only if time reversal symmetry (T) is violated. No edm of any particle has yet been discovered. CP-violation, equivalent to T-violation by the CPT theorem, does occur in Kaon decays and can be accounted for by the standard model. However, this mechanism leads to an electron edm d(sub e) of the order of 10(exp -38) e cm, whereas the current experimental bound on d(sub e) is about 10(exp -27) e cm. However, well-motivated extensions of the standard model such as supersymmetric theories do predict that de could be as large as the current bound. In addition, CP violation in the early universe is required to explain the preponderance of matter over anti-matter, but the exact mechanism of this CP violation is unclear. For these reasons, we are undertaking a new experimental program to determine de to an improved accuracy of 10(exp -29) e cm. Our experiment will use laser-cooled, trapped Cesium atoms to measure the atomic edm d(sub Cs) that occurs if d(sub e) is not zero. In order to do this, we will measure the energy splitting between the atoms spin states in parallel electric and magnetic fields. The signature of an edm would be a linear dependence of the splitting on the electric field E due to the interaction - d(sub Cs) dot E. Our measurement will be much more sensitive than previous measurements because atoms can be stored in the trap for tens of seconds, allowing for much narrower Zeeman resonance linewidths. Also, our method eliminates the most important systematic errors, proportional to atomic velocity, which have limited previous experiments. In this presentation, we will describe the design of our new apparatus, which is presently under construction. An important feature of our experimental apparatus is that magnetic field noise will be suppressed to a very low value of the order of 1 fT/(Hz)1/2. This requires careful attention to the Johnson noise currents in the chamber, which have not been important
Dynamically fluctuating electric dipole moments in fullerene-based magnets
Kambe, Takashi; Oshima, Kokichi
2014-01-01
We report here the direct evidence of the existence of a permanent electric dipole moment in both crystal phases of a fullerene-based magnet—the ferromagnetic α-phase and the antiferromagnetic α′-phase of tetra-kis-(dimethylamino)-ethylene-C60 (TDAE-C60)—as determined by dielectric measurements. We propose that the permanent electric dipole originates from the pairing of a TDAE molecule with surrounding C60 molecules. The two polymorphs exhibit clear differences in their dielectric responses at room temperature and during the freezing process with dynamically fluctuating electric dipole moments, although no difference in their room-temperature structures has been previously observed. This result implies that two polymorphs have different local environment around the molecules. In particular, the ferromagnetism of the α-phase is founded on the homogeneous molecule displacement and orientational ordering. The formation of the different phases with respect to the different rotational states in the Jahn–Teller distorted C60s is also discussed. PMID:25236361
Leptophilic dark matter and the anomalous magnetic moment of the muon
Agrawal, Prateek; Chacko, Zackaria; Verhaaren, Christopher B.
2014-08-26
We consider renormalizable theories such that the scattering of dark matter off leptons arises at tree level, but scattering off nuclei only arises at loop. In this framework, the various dark matter candidates can be classified by their spins and by the forms of their interactions with leptons. In this study, we determine the corrections to the anomalous magnetic moment of the muon that arise from its interactions with dark matter. We then consider the implications of these results for a set of simplified models of leptophilic dark matter. When a dark matter candidate reduces the existing tension between themore » standard model prediction of the anomalous magnetic moment and the experimental measurement, the region of parameter space favored to completely remove the discrepancy is highlighted. Conversely, when agreement is worsened, we place limits on the parameters of the corresponding simplified model. These bounds and favored regions are compared against the experimental constraints on the simplified model from direct detection and from collider searches. Although these constraints are severe, we find there do exist limited regions of parameter space in these simple theories that can explain the observed anomaly in the muon magnetic moment while remaining consistent with all experimental bounds.« less
Leptophilic dark matter and the anomalous magnetic moment of the muon
Agrawal, Prateek; Chacko, Zackaria; Verhaaren, Christopher B.
2014-08-26
We consider renormalizable theories such that the scattering of dark matter off leptons arises at tree level, but scattering off nuclei only arises at loop. In this framework, the various dark matter candidates can be classified by their spins and by the forms of their interactions with leptons. In this study, we determine the corrections to the anomalous magnetic moment of the muon that arise from its interactions with dark matter. We then consider the implications of these results for a set of simplified models of leptophilic dark matter. When a dark matter candidate reduces the existing tension between the standard model prediction of the anomalous magnetic moment and the experimental measurement, the region of parameter space favored to completely remove the discrepancy is highlighted. Conversely, when agreement is worsened, we place limits on the parameters of the corresponding simplified model. These bounds and favored regions are compared against the experimental constraints on the simplified model from direct detection and from collider searches. Although these constraints are severe, we find there do exist limited regions of parameter space in these simple theories that can explain the observed anomaly in the muon magnetic moment while remaining consistent with all experimental bounds.
Experimental determination of the magnetic dipole moment of candidate magnetoreceptor cells in trout
NASA Astrophysics Data System (ADS)
Winklhofer, M.; Eder, S.; Cadioiu, H.; McNaughton, P. A.; Kirschvink, J. L.
2011-12-01
Based on histological, physiological, and physical evidence, Walker et al (1997) and Diebel et al (2000) have identified distinctive cells in the olfactory epithelium of the rainbow trout (Onchorynchus mykiss) that contain magnetite and are closely associated with neurons that respond to changes in magnetic field. To put biophysical constraints on the possible transduction mechanism of magnetic signals, and in particular, to find out if the intracellular magnet is free to rotate or rather firmly anchored within the cell body, we have studied the magneto-mechanical response of isolated candidate receptor cells in suspension using a light microscope equipped with two pairs of Helmholtz coils. From the characteristic re-orientation time of suspended cells after a change in magnetic field direction, we have determined the magnitude of the magnetic dipole moment of the cells in function of the external field strength (0.4 mT to 3.2 mT) in order to find out whether or not the natural magnetic moment is remanence-based or induced (i.e., single-domain vs. superparamagnetic/multi-domain). Results: 1) The mechanical response of isolated cells to a change in magnetic field direction was always immediate, irrespective of the direction of change, which implies that the intracellular magnet is not free to rotate in the cell, but rather rigidly attached, probably to the plasma membrane, which is also suggested by our confocal fluorescence-microscope studies. 2) The cellular dipole moment turned out to be independent of the external field strength. Thus, the natural magnetic dipole moment is based on magnetic remanence, which points to single-domain particles and corroborates the results by Diebel et al (2000), who obtained switching fields consistent with single-domain magnetite. 3). The magnetic dipole moment is found to be of the order of several tens of fAm2, which greatly exceeds previous estimates (0.5 fAm2), and thus is similar to values reported for the most strongly
Stepanow, Sebastian; Honolka, Jan; Gambardella, Pietro; Vitali, Lucia; Abdurakhmanova, Nasiba; Tseng, Tzu-Chun; Rauschenbach, Stephan; Tait, Steven L; Sessi, Violetta; Klyatskaya, Svetlana; Ruben, Mario; Kern, Klaus
2010-09-01
The magnetic properties of isolated TbPc(2) molecules supported on a Cu(100) surface are investigated by X-ray magnetic circular dichroism at 8 K in magnetic fields up to 5 T. The crystal field and magnetic properties of single molecules are found to be robust upon adsorption on a metal substrate. The Tb magnetic moment has Ising-like magnetization; XMCD spectra combined with multiplet calculations show that the saturation orbital and spin magnetic moment values reach 3 and 6 mu(B), respectively.
NiPt/Rh(111): A stable surface alloy with enhanced magnetic moments
NASA Astrophysics Data System (ADS)
Imam, Mighfar; Marathe, Madhura; Narasimhan, Shobhana
2009-04-01
We have performed ab initio density functional theory calculations to investigate the miscibility and magnetic properties of pseudomorphically grown monolayers of Ni xPt 1- x surface alloys on a Rh(111) substrate. We find that the formation of this alloy is energetically favored over phase-segregated forms, and its magnetic moment is also enhanced. A significant contribution to this enhanced magnetic moment is found to come from the induced moments on the otherwise non-magnetic elements Pt and Rh. A low concentration of Ni gives rise to a high magnetic moment per Ni atom. We find that a low effective coordination and a high non-spin-polarized density of states at the Fermi level are responsible for these enhanced moments.
Facility Measures Magnetic Fields
NASA Technical Reports Server (NTRS)
Honess, Shawn B.; Narvaez, Pablo; Mcauley, James M.
1991-01-01
Partly automated facility measures and computes steady near magnetic field produced by object. Designed to determine magnetic fields of equipment to be installed on spacecraft including sensitive magnetometers, with view toward application of compensating fields to reduce interfernece with spacecraft-magnetometer readings. Because of its convenient operating features and sensitivity of its measurements, facility serves as prototype for similar facilities devoted to magnetic characterization of medical equipment, magnets for high-energy particle accelerators, and magnetic materials.
Magnetic moment orientation of nano-islands by electrostriction along two directions
NASA Astrophysics Data System (ADS)
Wang, Y.; Chen, Y. W.; Cao, J. W.; Wang, T.; Bai, J. M.; Wei, F. L.
2016-06-01
This article introduces a new method to realize the 180° magnetic moment reversal of a ferromagnetic and ferroelectric heterostructure through electrostriction-induced magnetic anisotropy. A rectangular magnetic FeAl alloy island with a large magnetostrictive coefficient on a PZN (011) substrate was adopted in our investigation through micromagnetic simulation. Using electrostriction along the [11-1] and [1-11] directions, the magnetic moment was rotated from the long axis of the rectangular island to the direction of the strain and finally reversed to the opposite direction despite the strain sequence. The magnetic moment can be oriented to a certain direction through a certain sequence of strain if a several hundred Oe magnetic field is applied along the short axis of the island. The suitable stress-induced magnetic anisotropy energy and external magnetic field were also investigated. In consideration that a high magnetic field along the short axis leads to small thermal stability of the magnetic moment, the suitable value of stress-induced anisotropy energy is around the critical value where the stress can reverse the magnetic moment without a magnetic field. We compared the stress-induced magnetic reversal processes for same-sized semicircular, elliptical, and rectangular islands and found that the semicircular island can be more easily reversed.
Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)
NASA Astrophysics Data System (ADS)
White, B. D.; Yazici, D.; Ho, P.-C.; Kanchanavatee, N.; Pouse, N.; Fang, Y.; Breindel, A. J.; Friedman, A. J.; Maple, M. B.
2015-08-01
We report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ˜6.7-6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya-Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4 f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order; however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.
Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)
White, B. D.; Yazici, D.; Ho, P. -C.; Kanchanavatee, N.; Pouse, N.; Fang, Y.; Breindel, A. J.; Friedman, A. J.; Maple, M. B.
2015-07-20
Here, we report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ~6.7- 6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya- Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order;more » however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.« less
NASA Astrophysics Data System (ADS)
Balaev, D. A.; Dubrovskii, A. A.; Krasikov, A. A.; Stolyar, S. V.; Iskhakov, R. S.; Ladygina, V. P.; Khilazheva, E. D.
2013-10-01
The magnetic properties of antiferromagnetic nanoparticles of FeOOH · nH2O with sizes of 3-7 nm, which are products of vital functions of Klebsiella oxytoca bacteria, have been studied. Particles exhibit a superparamagnetic behavior. The characteristic blocking temperature is 23 K. Analysis of the magnetization curves shows that the mechanism of the formation of the uncompensated magnetic moment of particles is the random decompensation of magnetic moments of Fe3+ ions both on the surface and in the bulk of the antiferromagnetic particle. In this mechanism, the exchange coupling between the uncompensated magnetic moment of the particle and its antiferromagnetic "core" is implemented. It has been found that the temperature dependence of the uncompensated magnetic moment has the form 1 — const T 2.
Evidence of half-metallic interface magnetism via local moment formation in Co based Heusler alloys
Telling, N. D.; Keatley, P.S.; van der Laan, G.; Hicken, R.J.; Arenholz, E.; Sakuraba, Y.; Oogane, M.; Ando, Y.; Miyazaki, T.
2008-08-18
In this work we use a combination of x-ray magnetic circular and linear dichroism (XMCD and XMLD) techniques to examine the formation of local moments in Heusler alloys of the composition Co{sub 2}MnX (where X=Si or Al). The existence of local moments in a half-metallic system is reliant upon the band gap in the minority-spin states. By utilizing the element-specific nature of x-ray techniques we are able to explore the origin of the minority-spin band gap in the partial density of states (PDOS), via the degree of localization of moments on Co and Mn atoms. We observe a crucial difference in the localization of the Co moment when comparing Co{sub 2}MnSi (CMS) and Co{sub 2}MnAl (CMA) films that is consistent with the predicted larger minority-spin gap in the Co PDOS for CMS. These results provide important evidence for the dominant role of the Co minority-spin states in realizing half-metallic ferromagnetism (HMF) in these Heusler alloys. They also demonstrate a direct method for measuring the degree of interfacial HMF in the raw materials without the need for fabricating spin-transport devices.
Realizing high magnetic moments in fcc Fe nanoparticles through atomic structure stretch.
Baker, S H; Roy, M; Thornton, S C; Binns, C
2012-05-01
We describe the realization of a high moment state in fcc Fe nanoparticles through a controlled change in their atomic structure. Embedding Fe nanoparticles in a Cu(1-x)Au(x) matrix causes their atomic structure to switch from bcc to fcc. Extended x-ray absorption fine structure (EXAFS) measurements show that the structure in both the matrix and the Fe nanoparticles expands as the amount of Au in the matrix is increased, with the data indicating a tetragonal stretch in the Fe nanoparticles. The samples were prepared directly from the gas phase by co-deposition, using a gas aggregation source and MBE-type sources respectively for the nanoparticle and matrix materials. The structure change in the Fe nanoparticles is accompanied by a sharp increase in atomic magnetic moment, ultimately to values of ~2.5 ± 0.3 μ(B)/atom .
Gyrotropic Magnetic Effect and the Magnetic Moment on the Fermi Surface.
Zhong, Shudan; Moore, Joel E; Souza, Ivo
2016-02-19
The current density j^{B} induced in a clean metal by a slowly-varying magnetic field B is formulated as the low-frequency limit of natural optical activity, or natural gyrotropy. Working with a multiband Pauli Hamiltonian, we obtain from the Kubo formula a simple expression for α_{ij}^{GME}=j_{i}^{B}/B_{j} in terms of the intrinsic magnetic moment (orbital plus spin) of the Bloch electrons on the Fermi surface. An alternate semiclassical derivation provides an intuitive picture of the effect, and takes into account the influence of scattering processes in dirty metals. This "gyrotropic magnetic effect" is fundamentally different from the chiral magnetic effect driven by the chiral anomaly and governed by the Berry curvature on the Fermi surface, and the two effects are compared for a minimal model of a Weyl semimetal. Like the Berry curvature, the intrinsic magnetic moment should be regarded as a basic ingredient in the Fermi-liquid description of transport in broken-symmetry metals. PMID:26943554
NASA Astrophysics Data System (ADS)
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.; Alexandrov, E. B.; Dmitriev, S. P.; Dovator, N. A.; Geltenbort, P.; Ivanov, S. N.; Zimmer, O.
2015-12-01
In this work, the double chamber magnetic resonance spectrometer of the Petersburg Nuclear Physics Institute (PNPI) designed to measure the neutron electric dipole moment (EDM) is briefly described. A method for long storage of polarized ultracold neutrons in a resonance space with a superposed electric field collinear to the leading magnetic field is used. The results of the measurements carried out on the ILL reactor (Grenoble, France) are interpreted as the upper limit of the value of neutron EDM |dn| < 5.5 × 10-26 e cm at the 90% confidence level.
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.; Alexandrov, E. B.; Dmitriev, S. P.; Dovator, N. A.; Geltenbort, P.; Ivanov, S. N.; Zimmer, O.
2015-12-15
In this work, the double chamber magnetic resonance spectrometer of the Petersburg Nuclear Physics Institute (PNPI) designed to measure the neutron electric dipole moment (EDM) is briefly described. A method for long storage of polarized ultracold neutrons in a resonance space with a superposed electric field collinear to the leading magnetic field is used. The results of the measurements carried out on the ILL reactor (Grenoble, France) are interpreted as the upper limit of the value of neutron EDM vertical bar d{sub n} vertical bar < 5.5 × 10{sup –26}e cm at the 90% confidence level.
NASA Astrophysics Data System (ADS)
Mein, P.; Uitenbroek, H.; Mein, N.; Bommier, V.; Faurobert, M.
2016-06-01
Context. In the case of unresolved solar structures or stray light contamination, inversion techniques using four Stokes parameters of Zeeman profiles cannot disentangle the combined contributions of magnetic and nonmagnetic areas to the observed Stokes I. Aims: In the framework of a two-component model atmosphere with filling factor f, we propose an inversion method restricting input data to Q , U, and V profiles, thus overcoming ambiguities from stray light and spatial mixing. Methods: The V-moments inversion (VMI) method uses shifts SV derived from moments of V-profiles and integrals of Q2, U2, and V2 to determine the strength B and inclination ψ of a magnetic field vector through least-squares polynomial fits and with very few iterations. Moment calculations are optimized to reduce data noise effects. To specify the model atmosphere of the magnetic component, an additional parameter δ, deduced from the shape of V-profiles, is used to interpolate between expansions corresponding to two basic models. Results: We perform inversions of HINODE SOT/SP data for inclination ranges 0 <ψ< 60° and 120 <ψ< 180° for the 630.2 nm Fe i line. A damping coefficient is fitted to take instrumental line broadening into account. We estimate errors from data noise. Magnetic field strengths and inclinations deduced from VMI inversion are compared with results from the inversion codes UNNOFIT and MERLIN. Conclusions: The VMI inversion method is insensitive to the dependence of Stokes I profiles on the thermodynamic structure in nonmagnetic areas. In the range of Bf products larger than 200 G, mean field strengths exceed 1000 G and there is not a very significant departure from the UNNOFIT results because of differences between magnetic and nonmagnetic model atmospheres. Further improvements might include additional parameters deduced from the shape of Stokes V profiles and from large sets of 3D-MHD simulations, especially for unresolved magnetic flux tubes.
Magnetic permeability measurements and a lunar core
NASA Technical Reports Server (NTRS)
Goldstein, B. E.; Phillips, R. J.; Russell, C. T.
1976-01-01
Measurements of the magnetic field induced in the moon while it is in the geomagnetic tail lobes have been interpreted in terms of lunar magnetic permeability due to free iron content; such studies ignored the possibility that a highly conducting lunar core (Fe or FeS) would exclude magnetic fields with an apparent diamagnetic effect. Using lunar chemical and thermal models to determine plausible limits of magnetic permeability, we interpret measurements of the induced moment. The maximum likely radius of a lunar core is 580 km. Subsatellite and ALSEP measurements of the induced field are in disagreement. Resolving the differences is critical to determining whether a core could or does exist.
Probing the magnetic moment of FePt micromagnets prepared by focused ion beam milling
Overweg, H. C.; Haan, A. M. J. den; Eerkens, H. J.; Bossoni, L.; Oosterkamp, T. H.; Alkemade, P. F. A.; La Rooij, A. L.; Spreeuw, R. J. C.
2015-08-17
We investigate the degradation of the magnetic moment of a 300 nm thick FePt film induced by Focused Ion Beam (FIB) milling. A 1 μm × 8 μm rod is milled out of a film by a FIB process and is attached to a cantilever by electron beam induced deposition. Its magnetic moment is determined by frequency-shift cantilever magnetometry. We find that the magnetic moment of the rod is μ = 1.1 ± 0.1 × 10{sup −12} Am{sup 2}, which implies that 70% of the magnetic moment is preserved during the FIB milling process. This result has important implications for atom trapping and magnetic resonance force microscopy, which are addressed in this paper.
Blum, T; Boyle, P A; Izubuchi, T; Jin, L; Jüttner, A; Lehner, C; Maltman, K; Marinkovic, M; Portelli, A; Spraggs, M
2016-06-10
We report the first lattice QCD calculation of the hadronic vacuum polarization (HVP) disconnected contribution to the muon anomalous magnetic moment at physical pion mass. The calculation uses a refined noise-reduction technique that enables the control of statistical uncertainties at the desired level with modest computational effort. Measurements were performed on the 48^{3}×96 physical-pion-mass lattice generated by the RBC and UKQCD Collaborations. We find the leading-order hadronic vacuum polarization a_{μ}^{HVP(LO)disc}=-9.6(3.3)(2.3)×10^{-10}, where the first error is statistical and the second systematic. PMID:27341226
Blum, T; Boyle, P A; Izubuchi, T; Jin, L; Jüttner, A; Lehner, C; Maltman, K; Marinkovic, M; Portelli, A; Spraggs, M
2016-06-10
We report the first lattice QCD calculation of the hadronic vacuum polarization (HVP) disconnected contribution to the muon anomalous magnetic moment at physical pion mass. The calculation uses a refined noise-reduction technique that enables the control of statistical uncertainties at the desired level with modest computational effort. Measurements were performed on the 48^{3}×96 physical-pion-mass lattice generated by the RBC and UKQCD Collaborations. We find the leading-order hadronic vacuum polarization a_{μ}^{HVP(LO)disc}=-9.6(3.3)(2.3)×10^{-10}, where the first error is statistical and the second systematic.
Stuart Pittel and the f7/2Shell Revisited: Magnetic Moments in the Ca Isotopes
NASA Astrophysics Data System (ADS)
Benczer-Koller, N.; Kumbartzki, G.; Mertzimekis, T. J.; Sharon, Y. Y.; Speidel, K.-H.; Taylor, M. J.; Zamick, L.
2004-09-01
The study of the structure of the Ca isotopes occupied Stuart Pittel for many years at the beginning of his career. In spite of many experiments and theoretical investigations over the last thirty years, the Ca isotopes still provide considerable surprises. Recently, magnetic moments of 21+ states in 42,44,46Ca have been measured and will be discussed in terms of a model encompassing a two-component wave function representing particle-hole excitations of the 40Ca core and single particle configurations.
William Detmold; Tiburzi, Brian C.; Walker-Loud, Andre
2010-03-01
Nucleon properties are investigated in background electric fields. As the magnetic moments of baryons affect their relativistic propagation in constant electric fields, electric polarizabilities cannot be determined without knowledge of magnetic moments. We devise combinations of baryon two-point functions in external electric fields to isolate both observables. Using an ensemble of anisotropic gauge configurations with dynamical clover fermions, we demonstrate how magnetic moments and electric polarizabilities can be determined from lattice QCD simulations in background electric fields. We obtain results for both the neutron and proton. Our study is currently limited to electrically neutral sea quarks.
X-ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu.
Kukreja, R; Bonetti, S; Chen, Z; Backes, D; Acremann, Y; Katine, J A; Kent, A D; Dürr, H A; Ohldag, H; Stöhr, J
2015-08-28
We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10^{-5}μ_{B} on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10^{-3}μ_{B} per atom. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow. PMID:26371670
X-ray detection of transient magnetic moments induced by a spin current in Cu
Kukreja, R.; Bonetti, S.; Chen, Z.; Backes, D.; Acremann, Y.; Katine, J.; Kent, A. D.; Durr, H. A.; Ohldag, H.; Stohr, J.
2015-08-24
We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10^{–5}_{μB} on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott’s two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10^{–3}_{μB} per atom. As a result, this reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.
Zatsiupa, A.A.; Bashkirov, L.A.; Troyanchuk, I.O.; Petrov, G.S.; Galyas, A.I.; Lobanovsky, L.S.; Truhanov, S.V.
2014-04-01
Magnetic susceptibility for ferrite Bi{sub 25}FeO{sub 39} is measured at 5–950 K in the magnetic field of 0.86 T. It is shown that Bi{sub 25}FeO{sub 39} is paramagnetic in the temperature range 5−950 K. The saturation magnetization is equal to 5.04μ{sub B} per formula unit at 5 K in a magnetic field of 10 T. It is found that at 5−300 K the effective magnetic moment of Fe{sup 3+} ions in Bi{sub 25}FeO{sub 39} is equal to 5.82μ{sub B}. - Graphical abstract: The dependence of the magnetization (n, μ{sub B}) on the magnetic field for one formula unit of Bi{sub 25}FeO{sub 39} at 5 K. - Highlights: • Magnetic susceptibility for Bi{sub 25}FeO{sub 39} is measured at 5–950 K in the magnetic field of 0.86 T. • It is shown that Bi{sub 25}FeO{sub 39} is paramagnetic in the temperature range 5−950 K. • The saturation magnetization is equal to 5.04μ{sub B} per formula unit at 5 K in a magnetic field of 10 T.
(83)Kr nuclear magnetic moment in terms of that of (3)He.
Makulski, Włodzimierz
2014-08-01
High resolution NMR spectroscopy was applied to precisely determine the (83)Kr nuclear magnetic dipole moment on the basis of new results available for nuclear magnetic shielding in krypton and helium-3 atoms. Small amounts of (3)He as the solutes and (83)Kr as the buffer gas were observed in (3)He and (83)Kr NMR spectra at the constant external field, B0 = 11.7578 T. In each case, the resonance frequencies (ν(He) and ν(Kr)) were linearly dependent on the density of gaseous solvent. The extrapolation of experimental points to the zero density of gaseous krypton allowed for the evaluation of both resonance frequencies free from intermolecular interactions. By combining these measurements with the recommended (83)Kr chemical shielding value, the nuclear magnetic moment could be determined with much better precision than ever before, μ((83)Kr) = -0.9707297(32)μN, with the improvement due to the greater accuracy of the spectral data.
(83)Kr nuclear magnetic moment in terms of that of (3)He.
Makulski, Włodzimierz
2014-08-01
High resolution NMR spectroscopy was applied to precisely determine the (83)Kr nuclear magnetic dipole moment on the basis of new results available for nuclear magnetic shielding in krypton and helium-3 atoms. Small amounts of (3)He as the solutes and (83)Kr as the buffer gas were observed in (3)He and (83)Kr NMR spectra at the constant external field, B0 = 11.7578 T. In each case, the resonance frequencies (ν(He) and ν(Kr)) were linearly dependent on the density of gaseous solvent. The extrapolation of experimental points to the zero density of gaseous krypton allowed for the evaluation of both resonance frequencies free from intermolecular interactions. By combining these measurements with the recommended (83)Kr chemical shielding value, the nuclear magnetic moment could be determined with much better precision than ever before, μ((83)Kr) = -0.9707297(32)μN, with the improvement due to the greater accuracy of the spectral data. PMID:24842240
Current status of the measurement of the anapole moment
NASA Astrophysics Data System (ADS)
Sheng, Dong; Perez Galvan, Adrian; Hood, Jonathan; Orozco, Luis
2009-05-01
We present the current status of the experimental effort towards the measurement of the anapole moment in different isotopes of francium. The anapole is a parity-violating, time-reversal conserving nuclear moment that arises from the weak interaction among nucleons. Due to the electromagnetic interaction between electrons and nucleons, atomic physics gives the unique possibility to probe the weak interaction in the low energy regime. Our experimental scheme involves driving a parity forbidden E1 transition between hyperfine ground states in a series of francium isotopes inside a blue detuned dipole trap at the electric antinode of a microwave cavity. The experiment will make use of the ISAC radioactive beam facility at TRIUMF. The system is currently being tested with rubidium.
Vacancy-induced intrinsic magnetic impurity with quasilocalized spin moment in graphene
NASA Astrophysics Data System (ADS)
Li, Yang; He, Jing; Kong, Xiao; Kou, Su-Peng
2014-11-01
By considering the Hubbard model on a honeycomb lattice, we develop a theory for intrinsic magnetic impurities (MIs) with quasilocalized spin moments induced by the vacancies in graphene. Because the intrinsic MIs are characterized by the zero modes that are orthogonal to the itinerant electrons, their properties are significantly different from those of Anderson MIs with well-localized spin moments.
NASA Astrophysics Data System (ADS)
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.
D.B. Leinweber; S. Boinepalli; A.W. Thomas; A.G. Williams; R.D. Young; J.B. Zhang; J.M. Zanotti
2004-06-01
Systematic uncertainties in the recent precise determination of the strangeness magnetic moment of the nucleon are identified and quantified. In summary, G{sub M}{sup s} = -0.046 {+-} 0.019 {micro}{sub N}.
Robust magnetic moments on the basal plane of the graphene sheet effectively induced by OH groups
Tang, Tao; Tang, Nujiang; Zheng, Yongping; Wan, Xiangang; Liu, Yuan; Liu, Fuchi; Xu, Qinghua; Du, Youwei
2015-01-01
Inducing robust magnetic moments on the basal plane of the graphene sheet is very difficult, and is one of the greatest challenges in the study of physical chemistry of graphene materials. Theoretical studies predicted that introduction of a kind of sp3-type defects formed by OH groups is an effective pathway to achieve this goal [Boukhvalov, D. W. & Katsnelson, M. I. ACS Nano 5, 2440–2446 (2011)]. Here we demonstrate that OH groups can efficiently induce robust magnetic moments on the basal plane of the graphene sheet. We show that the inducing efficiency can reach as high as 217 μB per 1000 OH groups. More interestingly, the magnetic moments are robust and can survive even at 900°C. Our findings highlight the importance of OH group as an effective sp3-type candidate for inducing robust magnetic moments on the basal plane of the graphene sheet. PMID:25677174
Low magnetic moment PIN diodes for high field MRI surface coils.
Voskoboynik, Pavel; Joos, Ronald D; Doherty, W E; Goldfarb, Ron B
2006-12-01
Positive-intrinsic-negative (PIN) silicon diodes are commonly used in magnetic resonance imaging (MRI) coils to perform active or passive blocking and detuning, or to disable circuit functions. However, diode packages with large magnetic moments are known to cause image artifacts in high field MRI systems. In this study, diode packages with low magnetic moment were designed by compensating components of ferromagnetic nickel and paramagnetic tungsten with diamagnetic silver. The new diodes have an initial positive susceptibility up to fields of 1 T and a negative susceptibility from 1 to 7 T. Their magnetic moments are one to two orders of magnitude smaller than those of standard diodes; moments as small as 20 nJ/T at 7 T were achieved. PMID:17278801
Electron magnetic moment from geonium spectra: Early experiments and background concepts
NASA Astrophysics Data System (ADS)
van Dyck, Robert S., Jr.; Schwinberg, Paul B.; Dehmelt, Hans G.
1986-08-01
The magnetic moment of a free electron has been measured by observing both its low-energy spin and cyclotron resonances (at νs=ωs/2π and νc=ωc/2π, respectively) by means of a sensitive frequency-shift technique. Using radiation and tuned-circuit damping of a single electron, isolated in a special anharmonicity-compensated Penning trap, also cooled to 4 K, the electron's motion is brought nearly to rest, thus preparing it in a cold quasipermanent state of the geonium ``atom.'' The magnetic-coupling scheme, described as a continuous Stern-Gerlach effect, is made possible through a weak Lawrence magnetic bottle which causes the very narrow axial resonance, at νz=ωz/2π for the harmonically bound electron, to change in frequency by a small fixed amount δ per unit change in magnetic quantum number. Spin flips are indirectly induced by a scheme which weakly drives the axial motion at the νa=ωa/2π spin-cyclotron difference frequency within the inhomogeneous magnetic field, thus yielding a measure of ωa≡ωs-ωc. The magnetic moment μs in terms of the Bohr magneton μB equals (1/2) the spin's g factor, which in turn is described by ωs and ωc: g=2μs/μB=2ωs/ωc. In a Penning trap, however, these resonance frequencies are obtained from the observed cyclotron frequency at ω'c=ωc-δe and the observed anomaly frequency at ω'a=ωs-ω'c, which are related by the small electric shift δe computed using the measured axial frequency and 2δeω'c=ωz 2. This last expression, derived for a perfectly axially symmetric trap, happens to be practically invariant against small imperfections in the electric quadrupole field (error in ωc<10-16). The magnetic-bottle-determined line shapes are analyzed and found to have sharp low-frequency edge features which correspond to the electron being temporarily at the trap center and at the bottom of the magnetic well. Relativistic shifts are considered and found to be <10-11. Our result at the time of submission, g/2=1.001 159
Francium spectroscopy and a proposed anapole moment measurement
NASA Astrophysics Data System (ADS)
Gomez, Eduardo
Francium is an attractive atom to study the weak interaction. Nuclear weak interactions such as the one responsible for the anapole moment are enhanced for heavy nuclei. We propose a method to measure the anapole moment in a chain of francium isotopes. The success of this proposal requires a high efficiency trap for the francium atoms produced in a nuclear fusion reaction. Our current trap has an efficiency above 1%, more than a factor of fifty improvement over the previous trap, and allows us to capture 104--10 5 atoms every 20 s. This thesis presents the measurement of the lifetime of the 8s level in francium and the corresponding level (6 s) in rubidium. We measure the lifetime of the 7s and 6p levels and the hyperfine splitting of the 7 s level in rubidium to complement the study of the corresponding levels in francium. The comparison of measurements in francium and rubidium with theoretical predictions enhances our confidence in the calculated wave functions required for the extraction of interaction constants from a Parity Non-Conservation measurement.
High-Precision Microwave Spectroscopy of Muonium for Determination of Muonic Magnetic Moment
NASA Astrophysics Data System (ADS)
Torii, H. A.; Higashi, Y.; Higuchi, T.; Matsuda, Y.; Mizutani, T.; Tajima, M.; Tanaka, K. S.; Ueno, Y.; Fukao, Y.; Iinuma, H.; Ikedo, Y.; Kadono, R.; Kawamura, N.; Koda, A.; Kojima, K. M.; Mibe, T.; Miyake, Y.; Nagamine, K.; Nishiyama, K.; Ogitsu, T.; Okubo, R.; Saito, N.; Sasaki, K.; Shimomura, K.; Strasser, P.; Sugano, M.; Toyoda, A.; Ueno, K.; Yamamoto, A.; Yoshida, M.; Ishida, K.; Iwasaki, M.; Kamigaito, O.; Tomono, D.; Kanda, S.; Kubo, K.; Aoki, M.; Torikai, E.; Kawall, D.
2016-02-01
The muonium atom is a system suitable for precision measurements for determination of muon’s fundamental properties as well as for the test of quantum electrodynamics (QED). A microwave spectroscopy experiment of this exotic atom is being prepared at J-PARC, jointly operated by KEK and JAEA in Japan, aiming at an improved relative precision at a level of 10-8 in determination of the muonic magnetic moment. A major improvement of statistical uncertainty is expected with the higher muon intensity of the pulsed beam at J-PARC, while reduction of various sources of systematic uncertainties are being studied: those arising from microwave power fluctuations, magnetic field inhomogeneity, muon stopping distribution and atomic collisional shift of resonance frequencies. Experimental strategy and methods are presented in this paper, with an emphasis on our recent development of apparatuses and evaluation of systematic uncertainties.
CP-violating effect of the Th nuclear magnetic quadrupole moment: accurate many-body study of ThO.
Skripnikov, L V; Petrov, A N; Titov, A V; Flambaum, V V
2014-12-31
Investigations of CP violation in the hadron sector may be done using measurements in the ThO molecule. Recent measurements in this molecule improved the limit on the electron electric dipole moment (EDM) by an order of magnitude. Another time-reversal (T) and parity (P)-violating effect in 229ThO is induced by the nuclear magnetic quadrupole moment. We perform nuclear and molecular calculations to express this effect in terms of the strength constants of T, P-odd nuclear forces, neutron EDM, QCD vacuum angle θ, quark EDM, and chromo-EDM.
NASA Astrophysics Data System (ADS)
Shugo Suzuki,; Hidehisa Ohta,
2010-07-01
We study the orbital, spin, and total magnetic moments in uranium monochalcogenides, UX where X=S, Se, and Te, using the fully relativistic full-potential calculations based on the spin density functional theory. In particular, the orbital magnetic moments are calculated with the Dirac current. We employ two methods which adopt distinctly different basis sets; one is the fully relativistic full-potential linear-combination-of-atomic-orbitals (FFLCAO) method and the other is the fully relativistic full-potential mixed-basis (FFMB) method. Showing that the orbital magnetic moments calculated using the FFLCAO method and those calculated using the FFMB method agree very well with each other, we demonstrate that, in contrast to the conventional method, the method with the Dirac current enables us to calculate the orbital magnetic moments even if the basis set includes basis functions with no definite angular momenta, e.g., the plane waves in the FFMB method. Furthermore, it is found that the orbital magnetic moments obtained in this work are larger by nearly 0.4 μB than those obtained using the conventional method. This is crucial because the resultant differences in the total magnetic moments are about 30%. We compare the results of this work with those of previous theoretical and experimental studies.
Dynamics of the magnetic moments for chain of dipoles in domain wall
NASA Astrophysics Data System (ADS)
Shutyıˇ, Anatoliy M.; Sementsov, Dmitriy I.
2016-03-01
We report on the dynamics of the magnetic moment numerically simulated for a chain of the magnetic nanodots coupled through the dipole-dipole interaction and in the presence of the magnetic anisotropy of various types. It is shown that a static field applied to the system causes specific fluctuations of the transverse components of the magnetic moment leading to a sequence of the oscillation trains observed in the domain wall. Various oscillation modes governed by the external alternating field are revealed. The influence of the unidirectional and uniaxial anisotropy ("easy-plane" and "easy axis" anisotropy) on the system behavior is described.
Progress Towards Measurement of the Anapole Moment of 137 Ba19 F
NASA Astrophysics Data System (ADS)
Cahn, Sidney; Altuntas, Emine; Demille, David; Kozlov, Mikhail
2016-05-01
Weak interactions inside the nucleus produce a toroidal current distribution around the axis of nuclear spin. This current distribution, known as the nuclear anapole moment is the dominant source of nuclear spin-dependent parity violation (NSD-PV) effects for nuclei with nucleon number A >= 20.We propose to measure the anapole moment of 137 Ba19 F. To diagnose systematics and establish a measurement sequence we use 138 Ba19 F, which has negligible NSD-PV effects. 138 Ba19 F has a larger isotopic abundance and fewer hyperfine levels compared to those of 137 Ba19 F. Therefore fluorescence signals from 138 Ba19 F are approximately 26 times larger than those from 137 Ba19 F. Here we present planned improvements to our apparatus, including a magnetic hexapole lens to improve the molecular beam flux and preliminary spectroscopy measurements with 137 Ba19 F.
Nuclear magnetic moments of the ground states of sup 124 I, sup 126 I, and sup 130 I
Ohya, S.; Yamazaki, T.; Harasawa, T.; Katsurayama, M.; Mutsuro, N. ); Muto, S.; Heiguchi, K. )
1992-01-01
The nuclear magnetic moments of {sup 124}I, {sup 126}I, and {sup 130}I have been measured by the techniques of low-temperature nuclear orientation and nuclear magnetic resonance on oriented nuclei. The magnetic hyperfine splitting frequency {vert bar}{ital g}{mu}{sub {ital N}BHF}/{ital h}{vert bar} for {sup 124}I{ital Fe} was determined to be 630.2(2) MHz from a field-shift analysis of the measured resonances at the external field of 0.1, 0.2, 0.4, 0.6, and 0.8 T. The resonances for {sup 126}I{ital Fe} and {sup 130}I{ital Fe} were observed in an external magnetic field of 0.2 T at {nu}({sup 126}I{ital Fe})=627.7(2) MHz and {nu}({sup 130}I{ital Fe})=585.7(2) MHz, respectively. Using the recalculated hyperfine field of {ital B}{sub HF}({sup 131}I{ital Fe})=114.50(5) T, the magnetic moments were deduced: {vert bar}{mu}({sup 124}I,2{sup {minus}}){vert bar}=1.444(4){mu}{sub {ital N}}, {vert bar}{mu}({sup 126}I,2{sup {minus}}){vert bar}=1.436(5){mu}{sub {ital N}}, and {vert bar}{mu}({sup 130}I,5{sup +}){vert bar}=3.349(7){mu}{sub {ital N}}. The present value of the magnetic moment of {sup 124}I is very different from the value of 1.14(8){mu}{sub {ital N}} reported previously. The measured values of the magnetic moments are discussed using Lande formula.
Kapitza problem for the magnetic moments of synthetic antiferromagnetic systems
Dzhezherya, Yu. I.; Demishev, K. O.; Korenivskii, V. N.
2012-08-15
The dynamics of magnetization in synthetic antiferromagnetic systems with the magnetic dipole coupling in a rapidly oscillating field has been examined. It has been revealed that the system can behave similar to the Kapitza pendulum. It has been shown that an alternating magnetic field can be efficiently used to control the magnetic state of a cell of a synthetic antiferromagnet. Analytical relations have been obtained between the parameters of such an antiferromagnet and an external magnetic field at which certain quasistationary states are implemented.
Magnetization reversal of uncompensated Fe moments in exchangebiased Ni/FeF2 bilayers
Arenholz, Elke; Liu, Kai; Li, Zhipan; Schuller, Ivan K.
2006-01-01
The magnetization reversal of uncompensated Fe moments in exchange biased Ni/FeF{sub 2} bilayers was determined using soft x-ray magnetic circular and linear dichroism. The hysteresis loops resulting from the Fe moments are almost identical to those of the ferromagnetic Ni layer. However, a vertical loop shift indicates that some Fe moments are pinned in the antiferromagnetically ordered FeF{sub 2}. The pinned moments are oriented antiparallel to small cooling fields leading to negative exchange bias, but parallel to large cooling fields resulting in positive exchange bias. No indication for the formation of a parallel antiferromagnetic domain wall in the FeF{sub 2} layer upon magnetization reversal in the Ni layer was found.
Thomas, Martin; Kirchner, Barbara
2016-02-01
We present a new approach for calculating vibrational circular dichroism spectra by ab initio molecular dynamics. In the context of molecular dynamics, these spectra are given by the Fourier transform of the cross-correlation function of magnetic dipole moment and electric dipole moment. We obtain the magnetic dipole moment from the electric current density according to the classical definition. The electric current density is computed by solving a partial differential equation derived from the continuity equation and the condition that eddy currents should be absent. In combination with a radical Voronoi tessellation, this yields an individual magnetic dipole moment for each molecule in a bulk phase simulation. Using the chiral alcohol 2-butanol as an example, we show that experimental spectra are reproduced very well. Our approach requires knowing only the electron density in each simulation step, and it is not restricted to any particular electronic structure method. PMID:26771403
The evolution of the magnetic moment in a corrugated magnetic field.
Demokan, O.; Mirnov, V. V.
1997-09-01
In the first part, the equations of motion in a weakly corrugated, periodic magnetic field are linearized and solved by using paraxial approximation, to describe the model and the associated resonance condition. In the second part, the nonlinear evolution of the magnetic moment of resonant particles, in connection with their axial displacement is investigated analytically by using the multiple scale method. It is seen that the linear evolution is converted into a slow and periodic oscillation around the unperturbed value, with a considerable amplitude. The analytic expressions for the period and amplitude of the oscillations are derived and compared with the numerical simulations, which are also presented. Finally, the limitations of the paraxial approximation are concluded by investigating the numerical simulations, with actual field expressions. (c) 1997 American Institute of Physics.
Blum, Thomas; Chowdhury, Saumitra; Hayakawa, Masashi; Izubuchi, Taku
2015-01-01
The most compelling possibility for a new law of nature beyond the four fundamental forces comprising the standard model of high-energy physics is the discrepancy between measurements and calculations of the muon anomalous magnetic moment. Until now a key part of the calculation, the hadronic light-by-light contribution, has only been accessible from models of QCD, the quantum description of the strong force, whose accuracy at the required level may be questioned. A first principles calculation with systematically improvable errors is needed, along with the upcoming experiments, to decisively settle the matter. For the first time, the form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in such a framework, lattice QCD+QED and QED. A nonperturbative treatment of QED is used and checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed for which statistically significant signals are obtained. Initial results are promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
Measurements of Rudder Moments on an Airplane During Flight
NASA Technical Reports Server (NTRS)
Heidelberg, Ing V
1921-01-01
Tests indicated that: 1) C airplanes with two struts are extremely susceptible to aileron maneuvers, slight alterations of the aileron sufficing to compensate great unequalized moments; 2) great unequalized moments can be produced or neutralized by the unequalized alternation of the angle of attack below the outer and inner struts. Adjustment below the outer strut is the more effective of the two. 3) When a load of bombs is suspended beyond the center of the airplane, below the wings, the bombs need not be dropped simultaneously. 4) The propeller wash of a wide open engine has considerable influence on the position and operation of the elevator. The elevator is more susceptible in flight with the engine running than in gliding flight. 5) Adjustable tail planes are not advisable for D airplanes, nor for the C type, but they are, on the other hand, to be recommended for large size and giant airplanes in which the center of gravity changes during flight. 6) The aileron values obtained by wind tunnel measurements are about 10 percent too low, though otherwise applicable. For the elevator, the results of such measurements should be taken as mean values between flight with the engine running and gliding flight.
Saari, M. M. Sakai, K.; Kiwa, T.; Tsukada, K.; Sasayama, T.; Yoshida, T.
2015-05-07
We developed a highly sensitive AC/DC magnetometer using a high-temperature superconductor superconducting quantum interference device for the evaluation of magnetic nanoparticles in solutions. Using the developed system, we investigated the distribution of magnetic moments of iron oxide multi-core particles of 100 nm at various iron concentrations that are lower than 96 μg/ml by analyzing the measured magnetization curves. Singular value decomposition and non-regularized non-negative least-squares methods were used during the reconstruction of the distribution. Similar distributions were obtained for all concentrations, and the iron concentration could be determined from the measured magnetization curves. The measured harmonics upon the excitation of AC and DC magnetic fields curves agreed well with the harmonics simulated based on the reconstructed magnetization curves, implying that the magnetization curves of magnetic nanoparticles were successfully obtained as we will show in the article. We compared the magnetization curves between multi-core particles of 100 nm and 130 nm, composed of 12-nm iron oxide nanoparticles. A distinctive magnetic property between the 100 nm and 130 nm particles in low-concentration solutions was successfully characterized. The distribution characteristic of magnetic moments suggests that the net magnetic moment in a multi-core particle is affected by the size of the magnetic cores and their degree of aggregation. Exploration of magnetic properties with high sensitivity can be expected using the developed system.
NASA Astrophysics Data System (ADS)
Grujić, Marko M.; Tadić, Milan Ž.; Peeters, François M.
2014-11-01
In honeycomb Dirac systems with broken inversion symmetry, orbital magnetic moments coupled to the valley degree of freedom arise due to the topology of the band structure, leading to valley-selective optical dichroism. On the other hand, in Dirac systems with prominent spin-orbit coupling, similar orbital magnetic moments emerge as well. These moments are coupled to spin, but otherwise have the same functional form as the moments stemming from spatial inversion breaking. After reviewing the basic properties of these moments, which are relevant for a whole set of newly discovered materials, such as silicene and germanene, we study the particular impact that these moments have on graphene nanoengineered barriers with artificially enhanced spin-orbit coupling. We examine transmission properties of such barriers in the presence of a magnetic field. The orbital moments are found to manifest in transport characteristics through spin-dependent transmission and conductance, making them directly accessible in experiments. Moreover, the Zeeman-type effects appear without explicitly incorporating the Zeeman term in the models, i.e., by using minimal coupling and Peierls substitution in continuum and the tight-binding methods, respectively. We find that a quasiclassical view is able to explain all the observed phenomena.
Finite Volume Study of the Delta Magnetic Moments Using Dynamical Clover Fermions
Aubin, Christopher; Orginos, Konstantinos; Pascalutsa, Vladimir; Vanderhaeghen, Marc
2009-01-01
We calculate the magnetic dipole moment of the $\\Delta$ baryon using a background magnetic field on 2+1-flavors of clover fermions on anisotropic lattices. We focus on the finite volume effects that can be significant in background field studies, and thus we use two different spatial volumes in addition to several quark masses.
Quantum aspects of a moving magnetic quadrupole moment interacting with an electric field
Fonseca, I. C.; Bakke, K.
2015-06-15
The quantum dynamics of a moving particle with a magnetic quadrupole moment that interacts with electric and magnetic fields is introduced. By dealing with the interaction between an electric field and the magnetic quadrupole moment, it is shown that an analogue of the Coulomb potential can be generated and bound state solutions can be obtained. Besides, the influence of the Coulomb-type potential on the harmonic oscillator is investigated, where bound state solutions to both repulsive and attractive Coulomb-type potentials are achieved and the arising of a quantum effect characterized by the dependence of the harmonic oscillator frequency on the quantum numbers of the system is discussed.
Magnetic moments around the Z =40 shell closure: sup 91 Y sup m , sup 95 Zr, and sup 97 Nb
Berkes, I.; De Jesus, M.; Hlimi, B.; Massaq, M.; Sayouty, E.H. ); Heyde, K. )
1991-07-01
Magnetic moments around the {ital Z}=40 shell closure have been established using nuclear magnetic resonance on oriented nuclei in iron. From the resonance frequencies we established {vert bar}{mu}({sup 91}Y;9/2{sup +}){vert bar}=6.01({sub {minus}15}{sup +31}){mu}{sub {ital N}}, {vert bar}{mu}({sup 95}Zr; 5/2{sup +}){vert bar}=1.103(23){mu}{sub {ital N}}, {vert bar}{mu}({sup 97}Nb;9/2{sup +}){vert bar}=6.153(5){mu}{sub {ital N}}. The results obtained are discussed in the framework of particle-core coupling and, in more detail, using the Nilsson deformed single-particle model. It is shown that for certain deformation regions the measurement of the magnetic moment can give information on the nuclear quadrupole deformation.
NASA Technical Reports Server (NTRS)
Desch, M. D.; Kaiser, M. L.
1984-01-01
Determinations by spacecraft of the low-frequency radio spectra and radiation beam geometry of the magnetospheres of earth, Jupiter, and Saturn now permit a reliable assessment of the overall efficiency of the solar wind in stimulating intense, nonthermal radio bursts from these magnetospheres. It is found that earlier estimates of how magnetospheric radio output scales with the solar wind energy input must be greatly revised, with the result that, while the efficiency is much lower than previously thought, it is remarkably uniform from planet to planet. A 'radimetric Bode's law' is formulated from which a planet's magnetic moment can be estimated from its radio emission output. This law is applied to estimate the low-frequency radio power likely to be measured for Uranus by Voyager 2. It is shown how measurements of Uranus's radio flux can be used to estimate the planetary magnetic moment and solar wind stand-off distance before the in situ measurements.
Tang, Jiqiang; Xiang, Biao; Zhang, Yongbin
2014-07-01
For a magnetically suspended control moment gyroscope, stiffness and damping of magnetic bearing will influence modal frequency of a rotor. In this paper the relationship between modal frequency and stiffness and damping has been investigated. The mathematic calculation model of axial passive magnetic bearing (PMB) stiffness is developed. And PID control based on internal model control is introduced into control of radial active magnetic bearing (AMB), considering the radial coupling of axial PMB, a mathematic calculation model of stiffness and damping of radial AMB is established. According to modal analysis, the relationship between modal frequency and modal shapes is achieved. Radial vibration frequency is mainly influenced by stiffness of radial AMB; however, when stiffness increases, radial vibration will disappear and a high frequency bending modal will appear. Stiffness of axial PMB mainly affects the axial vibration mode, which will turn into high-order bending modal. Axial PMB causes bigger influence on torsion modal of the rotor.
Magnetic Field Measurements near Mars.
Smith, E J; Davis, L; Coleman, P J; Jones, D E
1965-09-10
During the encounter between Mariner IV and Mars on 14-15 July, no magnetic effect that could be definitely associated with the planet was evident in the magnetometer data. This observation implies that the Martian magnetic dipole moment is, at most, 3 x 10(-4) times that of the earth.
Phase formation, thermal stability and magnetic moment of cobalt nitride thin films
Gupta, Rachana; Pandey, Nidhi; Tayal, Akhil; Gupta, Mukul E-mail: dr.mukul.gupta@gmail.com
2015-09-15
Cobalt nitride (Co-N) thin films prepared using a reactive magnetron sputtering process are studied in this work. During the thin film deposition process, the relative nitrogen gas flow (R{sub N{sub 2}}) was varied. As R{sub N{sub 2}} increases, Co(N), Co{sub 4}N, Co{sub 3}N and CoN phases are formed. An incremental increase in R{sub N{sub 2}}, after emergence of Co{sub 4}N phase at R{sub N{sub 2}} = 10%, results in a linear increase of the lattice constant (a) of Co{sub 4}N. For R{sub N{sub 2}} = 30%, a maximizes and becomes comparable to its theoretical value. An expansion in a of Co{sub 4}N, results in an enhancement of the magnetic moment, to the extent that it becomes even larger than pure Co. Such larger than pure metal magnetic moment for tetra-metal nitrides (M{sub 4}N) have been theoretically predicted. Incorporation of N atoms in M{sub 4}N configuration results in an expansion of a (relative to pure metal) and enhances the itinerary of conduction band electrons leading to larger than pure metal magnetic moment for M{sub 4}N compounds. Though a higher (than pure Fe) magnetic moment for Fe{sub 4}N thin films has been evidenced experimentally, higher (than pure Co) magnetic moment is evidenced in this work.
Atomic moments in Mn_{2}CoAl thin films analyzed by X-ray magnetic circular dichroism
Jamer, M. E.; Assaf, B. A.; Sterbinsky, G. E.; Arena, D. A.; Heiman, D.
2014-12-05
Spin gapless semiconductors are known to be strongly affected by structural disorder when grown epitaxially as thin films. The magnetic properties of Mn_{2}CoAl thin films grown on GaAs (001) substrates are investigated here as a function of annealing. This study investigates the atomic-specific magnetic moments of Mn and Co atoms measured through X-ray magnetic circular dichroism as a function of annealing and the consequent structural ordering. Results indicate that the structural distortion mainly affects the Mn atoms as seen by the reduction of the magnetic moment from its predicted value.
EM Induction Experiment to Determine the Moment of a Magnet
ERIC Educational Resources Information Center
Najiya Maryam, K. M.
2014-01-01
If we drop a magnet through a coil, an emf is induced in the coil according to Faraday's law of electromagnetic induction. Here, such an experiment is done using expEYES kit. The plot of emf versus time has a specific shape with two peaks. A theoretical analysis of this graph is discussed here for both short and long cylindrical magnets.…
NASA Astrophysics Data System (ADS)
Bubnov, Andrey; Gubina, Nadezda; Zhukovsky, Vladimir
2016-05-01
We study vacuum polarization effects in the model of Dirac fermions with additional interaction of an anomalous magnetic moment with an external magnetic field and fermion interaction with an axial-vector condensate. The proper time method is used to calculate the one-loop vacuum corrections with consideration for different configurations of the characteristic parameters of these interactions.
Excitation of local magnetic moments by tunneling electrons
NASA Astrophysics Data System (ADS)
Gauyacq, Jean-Pierre; Lorente, Nicolás; Novaes, Frederico Dutilh
2012-05-01
The advent of milli-kelvin scanning tunneling microscopes (STM) with inbuilt magnetic fields has opened access to the study of magnetic phenomena with atomic resolution at surfaces. In the case of single atoms adsorbed on a surface, the existence of different magnetic energy levels localized on the adsorbate is due to the breaking of the rotational invariance of the adsorbate spin by the interaction with its environment, leading to energy terms in the meV range. These structures were revealed by STM experiments in IBM Almaden in the early 2000s for atomic adsorbates on CuN surfaces. The experiments consisted in the study of the changes in conductance caused by inelastic tunneling of electrons (IETS, inelastic electron tunneling spectroscopy). Manganese and Iron adatoms were shown to have different magnetic anisotropies induced by the substrate. More experiments by other groups followed up, showing that magnetic excitations could be detected in a variety of systems: e.g. complex organic molecules showed that their magnetic anisotropy was dependent on the molecular environment, piles of magnetic molecules showed that they interact via intermolecular exchange interaction, spin waves were excited on ferromagnetic surfaces and in Mn chains, and magnetic impurities have been analyzed on semiconductors. These experiments brought up some intriguing questions: the efficiency of magnetic excitations was very high, the excitations could or could not involve spin flip of the exciting electron and singular-like behavior was sometimes found at the excitation thresholds. These facts called for extended theoretical analysis; perturbation theories, sudden-approximation approaches and a strong coupling scheme successfully explained most of the magnetic inelastic processes. In addition, many-body approaches were also used to decipher the interplay between inelastic processes and the Kondo effect. Spin torque transfer has been shown to be effective in changing spin orientations of an
Microwave Cavity for Anapole Moment Measurement in Francium
NASA Astrophysics Data System (ADS)
Zhang, Jiehang; Sheng, Dong; Orozco, Luis
2011-05-01
We present a study of the Polka-Dot microwave plano-spherical mirror for a Fabry-Perot resonator. The microwave resonator is an essential element of the apparatus to measure the anapole moment in francium. A crucial requirement for the cavity is the mode-matching into the fundamental Gaussian TEM00 mode. We investigate new coupling mechanisms of the radiation into the cavity to suppress unwanted higher order modes. We are exploring the method of printing two dimensional array of holes and feeding in through horn antennas. According to a HFSS simulation, this method should improve significantly the mode purity in contrast to conventional antenna. We fabricate the mirrors on standard optical blank using standard film deposition techniques with lithographic method to print the pattern. Preliminary tests show resonances, with potential improvements of the Q factors. Work supported by DOE and NSF
Prospects for electric-dipole-moment measurements in radon
NASA Astrophysics Data System (ADS)
Chupp, Timothy
2014-09-01
A permanent electric dipole moment (EDM) of a particle or system would arise due to breaking of time-reversal, or equivalently CP symmetry. Experiments to date on the neutron, atoms and molecules have only set upper limits on EDMs. New techniques and systems in which the effects of CP violation would be greatly enhanced are driving the field forward. Systems that may be favorable for significant advances include 221,223Rn, where the combination of octupole collectivity and relatively closely spaced opposite parity levels would increase the nuclear Schiff moment by one or more orders of magnitude compared to other diamagnetic atoms, i.e. 199Hg. We have developed and tested at TRIUMF-ISAC an on-line EDM experiment that will collect and make measurements on the short-lived species (T1 / 2 ~ 25 m) featuring high-efficiency collection and spin-exchange polarization of noble-gas isotopes. Nuclear-structure issues include determining the octupole collectivity as well as the spacing of opposite parity levels. Experiments are underway at ISOLDE, NSCL and ISAC to study the nuclear structure of isotopes in this mass region. I will report on progress and comment on how we learn about the basic physical parameters of CP violation from EDM measurements. A permanent electric dipole moment (EDM) of a particle or system would arise due to breaking of time-reversal, or equivalently CP symmetry. Experiments to date on the neutron, atoms and molecules have only set upper limits on EDMs. New techniques and systems in which the effects of CP violation would be greatly enhanced are driving the field forward. Systems that may be favorable for significant advances include 221,223Rn, where the combination of octupole collectivity and relatively closely spaced opposite parity levels would increase the nuclear Schiff moment by one or more orders of magnitude compared to other diamagnetic atoms, i.e. 199Hg. We have developed and tested at TRIUMF-ISAC an on-line EDM experiment that will collect
Orbital magnetic moment instability at the spin reorientation transition of Nd2Fe14B
Garcia; Chaboy; Bartolome; Goedkoop
2000-07-10
Highly accurate soft-XMCD data recorded on a Nd2Fe14B single crystal, through the spin reorientation transition show that the average Fe orbital moment (a) is proportional to the macroscopic Fe anisotropy constant, and (b) diverges 15 K below the reorientation transition temperature. This divergence is indicative of a critical behavior and it is related to a tetragonal distortion. These results give experimental evidence of the mutual dependence between orbital moment, macroscopic magnetic anisotropy, and tetragonal distortion. Furthermore, it is argued that the critical behavior of the orbital moment is at the origin of similar divergences previously observed in Mossbauer and Hall-effect data.
Brisson, Nicholas M; Stratford, Paul W; Totterman, Saara; Tamez-Peña, José G; Beattie, Karen A; Adachi, Jonathan D; Maly, Monica R
2015-12-01
Investigations of joint loading in knee osteoarthritis (OA) typically normalize the knee adduction moment to global measures of body size (eg, body mass, height) to allow comparison between individuals. However, such measurements may not reflect knee size. This study used a morphometric measurement of the cartilage surface area on the medial tibial plateau, which better represents medial knee size. This study aimed to determine whether normalizing the peak knee adduction moment and knee adduction moment impulse during gait to the medial tibial bone-cartilage interface could classify radiographic knee OA severity more accurately than traditional normalization techniques. Individuals with mild (N = 22) and severe (N = 17) radiographic knee OA participated. The medial tibial bone-cartilage interface was quantified from magnetic resonance imaging scans. Gait analysis was performed, and the peak knee adduction moment and knee adduction moment impulse were calculated in nonnormalized units and normalized to body mass, body weight × height, and the medial tibial bone-cartilage interface. Receiver operating characteristic curves compared the ability of each knee adduction moment normalization technique to classify participants according to radiographic disease severity. No normalization technique was superior at distinguishing between OA severities. Knee adduction moments normalized to medial knee size were not more sensitive to OA severity.
Discovery of Dicke superradiation by system of nuclear magnetic moments
Kiselev, J.F.; Prudkoglyad, A.F.; Shumovsky, A.S.; Yukalov, V.I. . Lab. of Theoretical Physics)
1988-01-01
Spontaneous generation of the Dicke superradiation (SR) state has been found in the system of inversely polarised proton spins with frozen polarisation. SR is observed at the moment when the Larmor frequency crosses the resonance frequency of the passive oscillatory circuit. SR arises from incoherent maser generation of spins. The frequency of a SR generator can be returned from several hundreds of kilohertz to hundreds of megahertz at very low temperatures. Dependence of incoherent and coherent radiation on the initial polarisation has been investigated. A radio frequency analogue of the optical SR laser is shown to be possible both for weak-amplifying and for strong-amplifying active media, depending on the factor of filling and polarisation of nuclei. SR-reverse of negative polarisation is observed in the latter case.
Addendum to "Updating neutrino magnetic moment constraints" [Phys. Lett. B 753 (2016) 191-198
NASA Astrophysics Data System (ADS)
Cañas, B. C.; Miranda, O. G.; Parada, A.; Tórtola, M.; Valle, J. W. F.
2016-06-01
After the publication of this work we noticed that the uncertainties in the considered backgrounds in Borexino may affect our reported limit on the neutrino magnetic moment from Borexino data. Indeed, we have found that a more precise treatment of the uncertainties in the total normalization of these backgrounds results in a weaker sensitivity on the neutrino magnetic moment. This point will be hopefully improved in the near future thanks to the purification processes carried out in the second phase of the Borexino experiment. Meanwhile, however, we think it would be more reliable to adopt the bound on the neutrino magnetic moment reported by Borexino: μν < 5.4 ×10-11μB[1].
Neutral current induced {pi}{sup 0} production and neutrino magnetic moment
Athar, M. Sajjad; Chauhan, S.; Singh, S. K.
2008-08-01
We have studied the total cross section, Q{sup 2}, momentum and angular distributions for pions in the {nu}({nu}) induced {pi}{sup 0} production from nucleons. The calculations have been done for the weak production induced by the neutral current in the standard model and the electromagnetic production induced by neutrino magnetic moment. It has been found that with the present experimental limits on the muon neutrino magnetic moment {mu}{sub {nu}{sub {mu}}}, the electromagnetic contribution to the cross section for the {pi}{sup 0} production is small. The neutrino induced neutral current production of {pi}{sup 0}, while giving an alternative method to study the magnetic moment of neutrino {mu}{sub {nu}{sub {mu}}}, does not provide any improvement over the present experimental limit on {mu}{sub {nu}{sub {mu}}} from the observation of this process in future experiments at T2K and NO{nu}A.
Aharonov-Bohm scattering of relativistic Dirac particles with an anomalous magnetic moment
Lin Qionggui
2005-10-15
The Aharonov-Bohm scattering of relativistic spin-1/2 particles with an anomalous magnetic moment are studied. The scattering cross sections for unpolarized and polarized particles are obtained by solving the Dirac-Pauli equation. It is somewhat unexpected that the results are in general the same as those for particles without an anomalous magnetic moment. However, when the incident energy takes some special values, the cross section for polarized particles is dramatically changed. In these cases the helicity of scattered particles is not conserved. In particular, the helicity of particles scattered in the backward direction is all reversed. In the nonrelativistic limit, a very simple relation between the polarized directions of the incident and scattered particles is found, for both general and special incident energies. For particles without an anomalous magnetic moment this relation can be drawn from previous results but it appears to be unnoticed.
Laser trapping of radium for an electric dipole moment measurement
NASA Astrophysics Data System (ADS)
Mueller, P.; Sulai, I. A.; Trimble, W.; Ahmad, I.; Bailey, K.; Bishof, M.; Greene, J. P.; Guest, J. R.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Gould, H. A.
2008-05-01
The best limits on time-reversal violation in the nuclear sector are currently set through electric dipole moment (EDM) searches on the neutron and Hg-199. Recent theoretical calculations predict that atomic EDM measurements of certain octupole-deformed nuclei, e.g., in the radium isotopic chain, are two to three orders of magnitude more sensitive to the underlying time-reversal violation than the one in Hg-199. Ra-225, with nuclear spin 1/2 and a radioactive half-life of 15 days, is a particularly attractive candidate for a tabletop EDM measurement based on a laser-cooling and trapping approach. Towards this end, we have successfully cooled and trapped atoms of Ra-225 and Ra-226 in a magneto-optical trap -- a first for this rare element -- and have identified black-body radiation as a beneficial source of optical repumping. We will present our laser cooling scheme and ongoing measurements of atomic level energies, lifetimes, isotope shifts and hyperfine structure in radium and discuss our progress towards an EDM measurement of Ra-225 based on an optical dipole trap. This work is supported by DOE, Office of Nuclear Physics, under contract No. DE-AC02-06CH11357.
Space-based and Earth-based Prospects for Measuring the Moment of Inertia of Venus
NASA Astrophysics Data System (ADS)
Margot, Jean-Luc; Campbell, Donald B.; Ghigo, Frank D.
2016-10-01
The moment of inertia is an essential integral constraint on models of planetary interiors. Our ignorance about Venus's moment of inertia prevents us from obtaining definite answers to key questions related to the size of the core, the thermal evolution history of the planet, the absence of a global magnetic field, and the evolution of the spin state. The technical challenge and cost of Venus landers make a direct measurement of the core size with seismology unlikely in the near future. For the same reasons, lander-based measurements of the spin precession rate, which yields the moment of inertia, are improbable in the near term. Tracking of the spin axis orientation with spacecraft or Earth-based radar over a decade or more offers more promising avenues. We use a precession model and the characteristics of existing data sets to quantify measurement prospects. The best Magellan estimates of the pole orientation have uncertainties of ~15 arcseconds (Konopliv et al., 1999) and an epoch that corresponds to the mid-point of the observations (~Oct. 1993). We describe achievable measurement uncertainties for a variety of scenarios including an additional spacecraft data point (e.g., at epoch 2023) with comparable or better precision than that of Magellan. Our 14 existing Earth-based radar observations obtained in 2006-2014 are sufficient to improve upon the best Magellan values and to unambiguously detect Venus's spin precession. We describe these results and quantify the uncertainties achievable on spin precession rate and moment of inertia with additional observations in the 2016-2023 interval. The Earth-based radar technique yielded a measurement of the spin axis orientation of Mercury with <5 arcsecond precision (Margot et al., 2012) that was later validated to <1 arcsecond level agreement with an independent, MESSENGER-based estimate (Stark et al., 2015).
Production polarization and magnetic moment of Ξ¯+ antihyperons produced by 800-GeV/c protons
NASA Astrophysics Data System (ADS)
Ho, P. M.; Longo, M. J.; Nguyen, A.; Luk, K. B.; James, C.; Rameika, R.; Duryea, J.; Guglielmo, G.; Heller, K.; Johns, K.; Diehl, H. T.; Teige, S.; Thomson, G. B.; Zou, Y.
1990-10-01
The polarization of Ξ¯ + hyperons produced by 800-GeV/c protons in the inclusive reaction p+Be-->Ξ¯ ++X has been measured. The average polarization of the Ξ¯ +, at a mean xF=0.39 and pt=0.76 GeV/c, is -0.097+/-0.012+/-0.009. The magnetic moment of the Ξ¯ + is 0.657+/-0.028+/-0.020 nuclear magneton.
Effect of permanent-magnet irregularities in levitation force measurements.
Hull, J. R.
1999-10-14
In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a nonnegligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analog of Earnshaw's theorem, in which at the field-cooling position the vertical stiffness is equal to the sum of the horizontal stiffnesses, independent of angular distribution of magnetic moments within the PM.
Covariant Spectator Theory of np scattering: Deuteron magnetic moment and form factors
Gross, Franz L.
2014-06-01
The deuteron magnetic moment is calculated using two model wave functions obtained from 2007 high precision fits to $np$ scattering data. Included in the calculation are a new class of isoscalar $np$ interaction currents which are automatically generated by the nuclear force model used in these fits. After normalizing the wave functions, nearly identical predictions are obtained: model WJC-1, with larger relativistic P-state components, gives 0.863(2), while model WJC-2 with very small $P$-state components gives 0.864(2) These are about 1\\% larger than the measured value of the moment, 0.857 n.m., giving a new prediction for the size of the $\\rho\\pi\\gamma$ exchange, and other purely transverse interaction currents that are largely unconstrained by the nuclear dynamics. The physical significance of these results is discussed, and general formulae for the deuteron form factors, expressed in terms of deuteron wave functions and a new class of interaction current wave functions, are given.
Magnetic moment formation due to arsenic vacancies in LaFeAsO-derived superconductors.
Kikoin, Konstantin; Drechsler, Stefan-Ludwig; Koepernik, Klaus; Málek, Jiři; van den Brink, Jeroen
2015-07-14
Arsenic vacancies in LaFeAsO-derived superconductors are nominally non-magnetic defects. However, we find from a microscopic theory in terms of an appropriately modified Anderson-Wolff model that in their vicinity local magnetic moments form. They can arise because removing an arsenic atom breaks four strong, covalent bonds with the neighboring iron atoms. The moments emerging around an arsenic vacancy orient ferromagnetically and cause a substantial enhancement of the paramagnetic susceptibility in both the normal and superconducting state. The qualitative model description is supported by first principles band structure calculations of the As-vacancy related defect spectrum within a larger supercell.
Magnetic moment formation due to arsenic vacancies in LaFeAsO-derived superconductors
Kikoin, Konstantin; Drechsler, Stefan-Ludwig; Koepernik, Klaus; Málek, Jiři; van den Brink, Jeroen
2015-01-01
Arsenic vacancies in LaFeAsO-derived superconductors are nominally non-magnetic defects. However, we find from a microscopic theory in terms of an appropriately modified Anderson-Wolff model that in their vicinity local magnetic moments form. They can arise because removing an arsenic atom breaks four strong, covalent bonds with the neighboring iron atoms. The moments emerging around an arsenic vacancy orient ferromagnetically and cause a substantial enhancement of the paramagnetic susceptibility in both the normal and superconducting state. The qualitative model description is supported by first principles band structure calculations of the As-vacancy related defect spectrum within a larger supercell. PMID:26169486
NASA Astrophysics Data System (ADS)
Knowles, R.
1982-07-01
A general theory of moments for electrodynamic magnetic levitation systems has been developed using double Fourier series and dynamic circuit principles. Both employ Parseval's theorem using either wave constant derivatives or the polar waveconstant principle of the Fourier-Bessel/double Fourier series equivalence. A method for calculating angular derivatives of moments and forces is explained, and for all of these methods comparisons are made with experimental results obtained for single and split rail configurations. Extensions of dynamic circuit theory for tilted nonflat and circular magnets are also explained.
Magnetic moment formation due to arsenic vacancies in LaFeAsO-derived superconductors.
Kikoin, Konstantin; Drechsler, Stefan-Ludwig; Koepernik, Klaus; Málek, Jiři; van den Brink, Jeroen
2015-01-01
Arsenic vacancies in LaFeAsO-derived superconductors are nominally non-magnetic defects. However, we find from a microscopic theory in terms of an appropriately modified Anderson-Wolff model that in their vicinity local magnetic moments form. They can arise because removing an arsenic atom breaks four strong, covalent bonds with the neighboring iron atoms. The moments emerging around an arsenic vacancy orient ferromagnetically and cause a substantial enhancement of the paramagnetic susceptibility in both the normal and superconducting state. The qualitative model description is supported by first principles band structure calculations of the As-vacancy related defect spectrum within a larger supercell. PMID:26169486
Large anomalous magnetic moment in three-dimensional Dirac and Weyl semimetals
NASA Astrophysics Data System (ADS)
van der Wurff, E. C. I.; Stoof, H. T. C.
2016-10-01
We investigate the effect of Coulomb interactions on the electromagnetic response of three-dimensional Dirac and Weyl semimetals. In a calculation reminiscent of Schwinger's seminal work on quantum electrodynamics, we find three physically distinct effects for the anomalous magnetic moment of the relativisticlike quasiparticles in the semimetal. In the case of nonzero doping, the anomalous magnetic moment is finite at long wavelengths and typically orders of magnitude larger than Schwinger's result. We also find interesting effects of one of the three new Hamiltonian terms on the topological surface states at the interface between vacuum and a Weyl semimetal. We conclude that observation of these effects should be within experimental reach.
Majorana neutrino magnetic moments in the gauge-mediated supersymmetry breaking MSSM
Gozdz, Marek; Kaminski, Wieslaw A.
2009-04-01
Supersymmetric models with broken R parity provide mechanisms that allow to generate Majorana neutrino masses and magnetic moments through virtual particle-sparticle loops. This constitutes an attractive alternative to the seesaw mechanism. In this paper, we present a detailed calculation of the transition magnetic moments of a Majorana neutrino in gauge-mediated supersymmetry breaking minimal supersymmetric standard model (MSSM) without R parity. We base our analysis on the renormalization group evolution of the MSSM parameters, which are unified at the grand unified theory scale.
Prediction of magnetic moment collapse in ZrFe{sub 2} under hydrostatic pressure
Zhang, Wenxu; Zhang, Wanli
2015-04-28
Electronic structure and magnetic properties of ZrFe{sub 2} in the cubic Laves phase are investigated by calculations based on density functional theory. The magnetic moment decreases with the increase of the hydrostatic pressure in an unusual way: Two-step magnetic collapse is predicted. The first one is a continuous change from 1.53 μ{sub B}/Fe to 0.63 μ{sub B}/Fe at about 3.6 GPa, and the other is from 0.25 μ{sub B}/Fe to the nonmagnetic state at about 15 GPa in a first order manner under the local spin density approximation of the exchange correlation potential. A metastable state with intermediate spin moment about 0.15 μ{sub B}/Fe may exist before that. We understand this process by the changes of density of states during it. The magnetic moment decreases under the pressure in the vicinity of the experimental lattice constant with dlnm/dp=−0.038 GPa{sup −1}. The spontaneous volume magnetostriction is 3.6%, which is huge enough to find potential applications in magnetostriction actuators and sensors. We suggest that the Invar effect of this compound may be understood when considering the magnetic moment variation according to the magnetostrictive model of Invar.
ARTEMIS Low Altitude Magnetic Field Measurements
NASA Astrophysics Data System (ADS)
Glassmeier, Karl-Heinz; Constantinescu, Dragos; Auster, Hans-Ulrich
2016-10-01
Since 2011, two spacecraft of the five THEMIS mission spacecraft are in orbit around the Moon. These two ARTEMIS probes provide for very interesting observations of plasma physical properties of the lunar environment. In particular, the very low periselene of the ARTEMIS probes allows for the detection of crustal magnetic features of our terrestrial companion. Repeated low passes over the same region are used to confirm the crustal origin of the measured magnetic field variations. Using a model for the decay of the magnetic field intensity and measurements at several altitudes, we estimate the magnetic moment and the depth of the equivalent dipole. Some of these magnetic anomalies are strong enough to produce upstream waves due to the interaction with the solar wind with the anomaly driven mini-magnetospheres.
Ultrafast dynamics of localized magnetic moments in the unconventional Mott insulator Sr2IrO4.
Krupin, O; Dakovski, G L; Kim, B J; Kim, J W; Kim, Jungho; Mishra, S; Chuang, Yi-De; Serrao, C R; Lee, W-S; Schlotter, W F; Minitti, M P; Zhu, D; Fritz, D; Chollet, M; Ramesh, R; Molodtsov, S L; Turner, J J
2016-08-17
We report a time-resolved study of the ultrafast dynamics of the magnetic moments formed by the [Formula: see text] states in Sr2IrO4 by directly probing the localized iridium 5d magnetic state through resonant x-ray diffraction. Using optical pump-hard x-ray probe measurements, two relaxation time scales were determined: a fast fluence-independent relaxation is found to take place on a time scale of 1.5 ps, followed by a slower relaxation on a time scale of 500 ps-1.5 ns. PMID:27310659
Ultrafast dynamics of localized magnetic moments in the unconventional Mott insulator Sr2IrO4
NASA Astrophysics Data System (ADS)
Krupin, O.; Dakovski, G. L.; Kim, B. J.; Kim, J. W.; Kim, Jungho; Mishra, S.; Chuang, Yi-De; Serrao, C. R.; Lee, W.-S.; Schlotter, W. F.; Minitti, M. P.; Zhu, D.; Fritz, D.; Chollet, M.; Ramesh, R.; Molodtsov, S. L.; Turner, J. J.
2016-08-01
We report a time-resolved study of the ultrafast dynamics of the magnetic moments formed by the {{J}\\text{eff}}=1/2 states in Sr2IrO4 by directly probing the localized iridium 5d magnetic state through resonant x-ray diffraction. Using optical pump–hard x-ray probe measurements, two relaxation time scales were determined: a fast fluence-independent relaxation is found to take place on a time scale of 1.5 ps, followed by a slower relaxation on a time scale of 500 ps–1.5 ns.
Disparate ultrafast dynamics of itinerant and localized magnetic moments in gadolinium metal
Frietsch, B.; Bowlan, J.; Carley, R.; Teichmann, M.; Wienholdt, S.; Hinzke, D.; Nowak, U.; Carva, K.; Oppeneer, P. M.; Weinelt, M.
2015-01-01
The Heisenberg–Dirac intra-atomic exchange coupling is responsible for the formation of the atomic spin moment and thus the strongest interaction in magnetism. Therefore, it is generally assumed that intra-atomic exchange leads to a quasi-instantaneous aligning process in the magnetic moment dynamics of spins in separate, on-site atomic orbitals. Following ultrashort optical excitation of gadolinium metal, we concurrently record in photoemission the 4f magnetic linear dichroism and 5d exchange splitting. Their dynamics differ by one order of magnitude, with decay constants of 14 versus 0.8 ps, respectively. Spin dynamics simulations based on an orbital-resolved Heisenberg Hamiltonian combined with first-principles calculations explain the particular dynamics of 5d and 4f spin moments well, and corroborate that the 5d exchange splitting traces closely the 5d spin-moment dynamics. Thus gadolinium shows disparate dynamics of the localized 4f and the itinerant 5d spin moments, demonstrating a breakdown of their intra-atomic exchange alignment on a picosecond timescale. PMID:26355196
Ni endohedral-doped C60 with duality of magnetic moments
NASA Astrophysics Data System (ADS)
Li, J. L.; Yang, G. W.
2010-06-01
We have performed the magnetic properties of Ni endohedral-doped C60 (Ni@C60) by the spin-polarized density functional calculations, and showed that there are three stable configurations depending on different sites of the doped Ni atoms. Due to the high hybridization and confinement effects, the magnetic moment of the Ni-encapsulated metallofullerenes has duality, i.e., altering between 2.02μB and zero, by positioning the Ni atom in the hollow cage of C60. These findings of the alternative magnetic moments of the Ni-encapsulated C60 implied that Ni@C60 could be expected to be promising as a single molecular magnetic switch.
Multi-moment advection scheme in three dimension for Vlasov simulations of magnetized plasma
Minoshima, Takashi; Matsumoto, Yosuke; Amano, Takanobu
2013-03-01
We present an extension of the multi-moment advection scheme [T. Minoshima, Y. Matsumoto, T. Amano, Multi-moment advection scheme for Vlasov simulations, Journal of Computational Physics 230 (2011) 6800–6823] to the three-dimensional case, for full electromagnetic Vlasov simulations of magnetized plasma. The scheme treats not only point values of a profile but also its zeroth to second order piecewise moments as dependent variables, and advances them on the basis of their governing equations. Similar to the two-dimensional scheme, the three-dimensional scheme can accurately solve the solid body rotation problem of a gaussian profile with little numerical dispersion or diffusion. This is a very important property for Vlasov simulations of magnetized plasma. We apply the scheme to electromagnetic Vlasov simulations. Propagation of linear waves and nonlinear evolution of the electron temperature anisotropy instability are successfully simulated with a good accuracy of the energy conservation.
Effect of longitudinal degree of freedom of magnetic moment in body-centered-cubic iron
Yin, Junqi; Eisenbach, Markus; Nicholson, Don M; Rusanu, Aurelian
2013-01-01
First principle calculations are performed to study the longitudinal degree of freedom of the magnetic moment in BCC iron. A model of the Heisenberg type of exchange interaction is proposed, which couples the spin and lattice degrees of freedom. Monte Carlo simulations are then applied to study the effect of thermal displacements on the magnetic phase transition in BCC Iron. The reason for the surprising success of fixed lattice Heisenberg models is explained.
Deuteron and triton magnetic moments from NMR spectra of the hydrogen molecule
NASA Astrophysics Data System (ADS)
Puchalski, Mariusz; Komasa, Jacek; Pachucki, Krzysztof
2015-08-01
We present a theory and calculations of the nuclear magnetic shielding with finite nuclear mass effects and determine the magnetic moments of deuteron and triton using the known NMR spectra of HD and HT molecules. The results μd=0.857 438 234 6 (53 ) μN and μt=2.978 962 471 (10 ) μN are more accurate and in good agreement with the currently accepted values.
Sum rules for magnetic moments and polarizabilities in QED and chiral effective-field theory
Barry Holstein; Vladimir Pascalutsa; Marc Vanderhaeghen
2005-08-01
We elaborate on a recently proposed extension of the Gerasimov-Drell-Hearn (GDH) sum rule which is achieved by taking derivatives with respect to the anomalous magnetic moment. The new sum rule features a linear relation between the anomalous magnetic moment and the dispersion integral over a cross-section quantity. We find some analogy of the linearized form of the GDH sum rule with the ''sideways dispersion relations''. As an example, we apply the linear sum rule to reproduce the famous Schwinger's correction to the magnetic moment in QED from a tree-level cross-section calculation and outline the procedure for computing the two-loop correction from a one-loop cross-section calculation. The polarizabilities of the electron in QED are considered as well by using the other forward-Compton-scattering sum rules. We also employ the sum rules to study the magnetic moment and polarizabilities of the nucleon in a relativistic chiral EFT framework. In particular we investigate the chiral extrapolation of these quantities.
A light Zeldovich-Konopinski-Mahmoud neutrino with a large magnetic moment
NASA Astrophysics Data System (ADS)
Ecker, G.; Grimus, W.; Neufeld, H.
1989-11-01
We propose a non-abelian extension of a Zeldovich-Konopinski-Mahmoud lepton number symmetry which gives rise to a naturally light Dirac neutrino with a magnetic moment of O(10 -11μB). The neutrino mass appears first at the two-loop level and is well below the experimental upper bound.
High-precision evaluation of the magnetic moment of the helion
Neronov, Yu. I. Seregin, N. N.
2012-11-15
NMR spectra of samples containing a mixture of hydrogen deuteride HD with pressure of about 80 atm and helium-3 with partial pressure of about 1 atm are analyzed. The ratio of the resonance frequencies of the nuclei, F({sup 3}He)/F(H{sub 2}), is determined to be 0.761786594(2), which is equal to the magnetic moment of the helion (bound in a helium atom) in the units of the magnetic moment of a proton (bound in molecular hydrogen). The uncertainty of two digits in the last place corresponds to a relative error of {delta}[F({sup 3}He)/F(H{sub 2})] = 2.6 Multiplication-Sign 10{sup -9}. The use of the known calculated data on the shielding of nuclei in the helium-3 atom ({sigma}({sup 3}He) = 59924(2) Multiplication-Sign 10{sup -9}) and on the shielding of protons in hydrogen ({sigma}(H{sub 2}) = 26288(2) Multiplication-Sign 10{sup -9}) yields a value of {mu}({sup 3}He)/{mu}{sub p} = -0.761812217(3) for the free magnetic moment of the helion in the units of the proton magnetic moment.
Electromagnetic Currents and Magnetic Moments in $\\chi$EFT
Saori Pastore, Luca Girlanda, Rocco Schiavilla, Michele Viviani, Robert Wiringa
2009-09-01
A two-nucleon potential and consistent electromagnetic currents are derived in chiral effective field theory ($\\chi$EFT) at, respectively, $Q^{\\, 2}$ (or N$^2$LO) and $e\\, Q$ (or N$^3$LO), where $Q$ generically denotes the low-momentum scale and $e$ is the electric charge. Dimensional regularization is used to renormalize the pion-loop corrections. A simple expression is derived for the magnetic dipole ($M1$) operator associated with pion loops, consisting of two terms, one of which is determined, uniquely, by the isospin-dependent part of the two-pion-exchange potential. This decomposition is also carried out for the $M1$ operator arising from contact currents, in which the unique term is determined by the contact potential. Finally, the low-energy constants (LEC's) entering the N$^2$LO potential are fixed by fits to the $np$ S- and P-wave phase shifts up to 100 MeV lab energies. Three additional LEC's are needed to completely specify the $M1$ operator at N$^3$L
Search for Trapped Electrons and a Magnetic Moment at Mars by Mariner IV.
O'gallagher, J J; Simpson, J A
1965-09-10
The Mariner IV spacecraft on 14-15 July 1965 passed within 9850 kilometers of Mars, carrying a solid-state charged-particle telescope which could detect electrons greater than 40 kiloelectron volts and protons greater than 1 million electron volts. The trajectory could have passed through a bow shock, a transition region, and a magnetospheric boundary where particles could be stably trapped for a wide range of Martian magnetic moments. No evidence of charged-particle radiation was found in any of these regions. In view of these results, an upper limit is established for the Martian magnetic moment provided it is assumed that the same physical processes leading to acceleration and trapping of electrons in Earth's magnetic field would be found in a Martian magnetic field. On this basis, the upper limit for the Martian magnetic moment is 0.1 percent that of Earth for a wide range of postulated orientations with respect to the rotational axis of Mars. The implications of these results for the physical and biological environment of Mars are briefly discussed.
Magnetic Moments of Delta and Omega- baryons with dynamical clover fermions
Aubin, Christopher; Orginos, Konstantinos; Pascalutsa, Vladimir; Vanderhaeghen, Marc
2009-01-01
We calculate the magnetic dipole moment of the Delta(1232) and Omega- baryons with 2+1-flavors of clover fermions on anisotropic lattices using a background magnetic field. This is the first dynamical calculation of these magnetic moments using a background field technique. The calculation for Omega- is done at the physical strange quark mass, with the result in units of the physical nuclear magneton Âµ_(Omega-) = -1.93(8)(12) (where the first error is statistical and the second is systematic) compared to the experimental number: -2.02(5). The Delta has been studied at three unphysical quark masses, corresponding to pion mass 366, 438, and 548 MeV. The pion-mass dependence is compared with the behavior obtained from chiral effective-field theory.
Das, Chinmoy; Vaidya, Shefali; Gupta, Tulika; Frost, Jamie M; Righi, Mattia; Brechin, Euan K; Affronte, Marco; Rajaraman, Gopalan; Shanmugam, Maheswaran
2015-10-26
Three cationic [Ln4 ] squares (Ln=lanthanide) were isolated as single crystals and their structures solved as [Dy4 (μ4 -OH)(HL)(H2 L)3 (H2 O)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)8 (1), [Tb4 (μ4 -OH)(HL)(H2 L)3 (MeOH)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)4 (2) and [Gd4 (μ4 -OH)(HL)(H2 L)3 (H2 O)2 (MeOH)2 ]Br2 ⋅(CH3 OH)4 ⋅(H2 O)3 (3). The structures are described as hydroxo-centered squares of lanthanide ions, with each edge of the square bridged by a doubly deprotonated H2 L(2-) ligand. Alternating current magnetic susceptibility measurements show frequency-dependent out-of-phase signals with two different thermally assisted relaxation processes for 1, whereas no maxima in χM " appears above 2.0 K for complex 2. For 1, the estimated effective energy barrier for these two relaxation processes is 29 and 100 K. Detailed ab initio studies reveal that complex 1 possesses a toroidal magnetic moment. The ab initio calculated anisotropies of the metal ions in complex 1 were employed to simulate the magnetic susceptibility by using the Lines model (POLY_ANISO) and this procedure yields J1 =+0.01 and J2 =-0.01 cm(-1) for 1 as the two distinct exchange interactions between the Dy(III) ions. Similar parameters are also obtained for complex 1 (and 2) from specific heat measurements. A very weak antiferromagnetic super-exchange interaction (J1 =-0.043 cm(-1) and g=1.99) is observed between the metal centers in 3. The magnetocaloric effect (MCE) was estimated by using field-dependent magnetization and temperature-dependent heat-capacity measurements. An excellent agreement is found for the -ΔSm values extracted from these two measurements for all three complexes. As expected, 3 shows the largest -ΔSm variation (23 J Kg(-1) K(-1) ) among the three complexes. The negligible magnetic anisotropy of Gd indeed ensures near degeneracy in the (2S+1) ground state microstates, and the weak super-exchange interaction facilitates dense population of low-lying excited states, all of
Das, Chinmoy; Vaidya, Shefali; Gupta, Tulika; Frost, Jamie M; Righi, Mattia; Brechin, Euan K; Affronte, Marco; Rajaraman, Gopalan; Shanmugam, Maheswaran
2015-10-26
Three cationic [Ln4 ] squares (Ln=lanthanide) were isolated as single crystals and their structures solved as [Dy4 (μ4 -OH)(HL)(H2 L)3 (H2 O)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)8 (1), [Tb4 (μ4 -OH)(HL)(H2 L)3 (MeOH)4 ]Cl2 ⋅(CH3 OH)4 ⋅(H2 O)4 (2) and [Gd4 (μ4 -OH)(HL)(H2 L)3 (H2 O)2 (MeOH)2 ]Br2 ⋅(CH3 OH)4 ⋅(H2 O)3 (3). The structures are described as hydroxo-centered squares of lanthanide ions, with each edge of the square bridged by a doubly deprotonated H2 L(2-) ligand. Alternating current magnetic susceptibility measurements show frequency-dependent out-of-phase signals with two different thermally assisted relaxation processes for 1, whereas no maxima in χM " appears above 2.0 K for complex 2. For 1, the estimated effective energy barrier for these two relaxation processes is 29 and 100 K. Detailed ab initio studies reveal that complex 1 possesses a toroidal magnetic moment. The ab initio calculated anisotropies of the metal ions in complex 1 were employed to simulate the magnetic susceptibility by using the Lines model (POLY_ANISO) and this procedure yields J1 =+0.01 and J2 =-0.01 cm(-1) for 1 as the two distinct exchange interactions between the Dy(III) ions. Similar parameters are also obtained for complex 1 (and 2) from specific heat measurements. A very weak antiferromagnetic super-exchange interaction (J1 =-0.043 cm(-1) and g=1.99) is observed between the metal centers in 3. The magnetocaloric effect (MCE) was estimated by using field-dependent magnetization and temperature-dependent heat-capacity measurements. An excellent agreement is found for the -ΔSm values extracted from these two measurements for all three complexes. As expected, 3 shows the largest -ΔSm variation (23 J Kg(-1) K(-1) ) among the three complexes. The negligible magnetic anisotropy of Gd indeed ensures near degeneracy in the (2S+1) ground state microstates, and the weak super-exchange interaction facilitates dense population of low-lying excited states, all of
Accurate Determination of Torsion and Pure Bending Moment for Viscoelastic Measurements
NASA Astrophysics Data System (ADS)
Wang, Yun-Che; Ko, Chih-Chin; Shiau, Li-Ming
Measurements of time-dependent material properties in the context of linear viscoelasticity, at a given frequency and temperature, require accurate determination of both loading and deformation that are subjected to the testing materials. A pendulum-type viscoelastic spectroscopy is developed to experimentally measure loss tangent and the magnitude of dynamic modulus of solid materials. The mechanical system of the device is based on the behavior of the cantilever beam, and torsion and pure bending moment are generated from the interaction between a permanent magnet and the Helmholtz coils. The strength of the magnetic interactions may be determined with a material with known mechanical properties, such as aluminum 6061T4 alloy. The sensitivity of the torque measurement is on the order of one micro N-m level. With the high accurate torque measurement and deformation detection from a laser-based displacement measurement system, viscoelastic properties of materials can be experimentally measured in different frequency regimes. Sinusoidal driving signals are adopted for measuring complex modulus in the sub-resonant regime, and dc bias driving for creep tests in the low frequency limit. At structural resonant frequencies, the full-width-at-half-maximum (FWHM) method or Lorentzian curve fitting method is adopted to extract material properties. The completion of determining material properties in the wide frequency spectrum may help to identify the deformation mechanisms of the material and to create better models for simulation work.
Sarafidis, C; Wilhelm, F; Rogalev, A; Gjoka, M; Kalogirou, O
2009-06-10
An element-specific study of the Nd(3)Fe(27.5)Ti(1.5) compound using the hard x-ray magnetic circular dichroism (XMCD) technique is presented. The Nd L(2) and L(3) edge XMCD, as well as the Fe K edge XMCD, were measured in a magnetically oriented sample, parallel and perpendicular to its alignment direction. The XMCD spectra were recorded at three different temperatures, above, below and in between the characteristic peaks that the specific compound presents in AC susceptibility measurements. By probing the Nd L edges and the Fe K edge XMCD, we found that the dipolar R(5d)-Fe(3d) exchange interaction behaves differently with temperature change than the Fe-Fe magnetic interaction. Those differences appear to be in the vicinity of the AC susceptibility characteristic peaks. An XMCD signal was recorded at the Ti K edge, revealing a small orbital polarization due to the hybridization with Fe atomic states. This demonstrates the existence of a small finite magnetic moment in Ti atoms. PMID:21825598
CPT Test with (anti)proton Magnetic Moments Based on Quantum Logic Cooling and Readout
NASA Astrophysics Data System (ADS)
Niemann, M.; Paschke, A.-G.; Dubielzig, T.; Ulmer, S.; Ospelkaus, C.
2014-01-01
Dehmelt and VanDyck's famous 1987 measurement of the electron and positron g-factor is still the most precise g-factor comparison in the lepton sector, and a sensitive test of possible CPT violation. A complementary g-factor comparison between the proton and the antiproton is highly desirable to test CPT symmetry in the baryon sector. Current experiments, based on Dehmelt's continuous Stern-Gerlach effect and the double Penning-trap technique, are making rapid progress. They are, however, extremely difficult to carry out because ground state cooling using cryogenic techniques is virtually impossible for heavy baryons, and because the continous Stern-Gerlach effect scales as μ/m, where m is the mass of the particle and μ its magnetic moment. Both difficulties will ultimately limit the accuracy. We discuss experimental prospects of realizing an alternative approach to a g-factor comparison with single (anti)protons, based on quantum logic techniques proposed by Heinzen and Wineland and by Wineland et al. The basic idea is to cool, control and measure single (anti)protons through interaction with a well-controlled atomic ion.
NASA Astrophysics Data System (ADS)
Mellor, Brett; Cruz Cortes, Efren; Busath, David; Mazzeo, Brian
2010-10-01
Protein structure, function, and interaction are, in part, a consequence of the low permittivity region surrounding the hydrophobic core of the molecule. We present a novel approach to estimate the dielectric constant of this region using measured and simulated first- and second-order charge moments. The second-order moment, the dipole moment, is measured using dielectric spectroscopy in a temperature-stable parallel-plate cell. The first-order moment, overall charge, and the dipole moment are calculated using structures from the Protein Data Bank and refined structures using molecular dynamics in CHARMM. The best estimate is evaluated in terms of the dielectric constant that minimizes the root mean square residual between measured and simulated charge moments. This method is carried out on the protein β-lactoglobulin, for which a dielectric constant in the range of 6 to 7 is estimated.
White, B. D.; Yazici, D.; Ho, P. -C.; Kanchanavatee, N.; Pouse, N.; Fang, Y.; Breindel, A. J.; Friedman, A. J.; Maple, M. B.
2015-07-20
Here, we report the physical properties of single crystals of the compounds CeT_{2}Cd_{20} (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ~6.7- 6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya- Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order; however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.
Magnetic moment of single vortices in YBCO nano-superconducting particle: Eilenberger approach
NASA Astrophysics Data System (ADS)
Zakharchuk, I.; Sharafeev, A.; Belova, P.; Safonchik, M.; Traito, K. B.; Lähderanta, E.
2013-12-01
Temperature dependence of single vortex magnetic moment in nanosize superconducting particles is investigated in the framework of quasiclassical Eilenberger approach. Such nanoparticles can be used for preparation of high-quality superconducting thin films with high critical current density. In contrast to bulk materials where the vortex magnetic moment is totally determined by flux quantum, in nano-sized specimens (with characteristic size, D, much less than effective penetration depth, λeff) the quantization rule is violated and magnetic moment is proportional to D2/λ2eff(T). Due to strong repulsion between vortices in nanoparticles only a single vortex can be trapped in them. Because of small size of particles the screening current of the vortex is located near the vortex core where the current is quite high and comparable to depairing currents. Therefore, the superconducting electron density, ns, depends on the current value and the distance from the vortex core. This effect is especially important for superconductors having gap nodes, such as YBCO. The current dependence of ns in nanoparticles is analogous to the Volovik effect in flux-line lattice in bulk samples. The magnitude of the effect can be obtained by comparing the temperature dependence of magnetic moment in the vortex and in the Meissner states. In the last case the value of screening current is small and superconducting response to the external field is determined by London penetration depth. Because of importance of nonlinear and nonlocal effects, the quantum mechanical Eilenberger approach is applied for description of the vortex in nanoparticles. The flattening of 1/λ2eff(T) dependence has been found. A comparison of the theoretical results with experimental magnetization data in Meissner and mixed states of YBCO nanopowders has been done. The presence of nonlinear and nonlocal effects in vortex current distribution is clearly visible. The obtained results are important for the description
Large enhancement of magnetic moment in L1(0) ordered FePt thin films by Nd substitutional doping
Xu, D. B.; Sun, C J; Chen, J. S.; Heald, S M; Sanyal, B.; Rosenberg, R. A.; Zhou, T. J.; Chow, G. M.
2015-07-01
We studied L1(0) ordered Fe50Pt50-xNdx alloy films, which showed a large enhancement (similar to 18.4% at room temperature and similar to 11.7% at 10 K) of magnetic moment with 6 atomic % of Nd. Analysis of the x-ray magnetic circular dichroism spectra at the Fe L-3,L-2 edges and Nd M-5,M-4 edges in Fe50Pt44Nd6 films indicated a significant contribution of the Nd orbital moment. The origin of the large enhancement of magnetic moment was attributed to the effect of ferromagnetic coupling of the total magnetic moments between Fe and Nd. Density functional theory based first principles calculations supported the experimental observations of increasing moment due to Nd substitution of Pt.
The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters.
Meyer, Jennifer; Tombers, Matthias; van Wüllen, Christoph; Niedner-Schatteburg, Gereon; Peredkov, Sergey; Eberhardt, Wolfgang; Neeb, Matthias; Palutke, Steffen; Martins, Michael; Wurth, Wilfried
2015-09-14
We present size dependent spin and orbital magnetic moments of cobalt (Con (+), 8 ≤ n ≤ 22), iron (Fen (+), 7 ≤ n ≤ 17), and nickel cluster (Nin (+), 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results. We discuss the application of scaling laws to the size dependent evolution of the spin and orbital magnetic moments per atom in the clusters. We find a spin scaling law "per cluster diameter," ∼n(-1/3), that interpolates between known atomic and bulk values. In remarkable contrast, the orbital moments do likewise only if the atomic asymptote is exempt. A concept of "primary" and "secondary" (induced) orbital moments is invoked for interpretation.
The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters.
Meyer, Jennifer; Tombers, Matthias; van Wüllen, Christoph; Niedner-Schatteburg, Gereon; Peredkov, Sergey; Eberhardt, Wolfgang; Neeb, Matthias; Palutke, Steffen; Martins, Michael; Wurth, Wilfried
2015-09-14
We present size dependent spin and orbital magnetic moments of cobalt (Con (+), 8 ≤ n ≤ 22), iron (Fen (+), 7 ≤ n ≤ 17), and nickel cluster (Nin (+), 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results. We discuss the application of scaling laws to the size dependent evolution of the spin and orbital magnetic moments per atom in the clusters. We find a spin scaling law "per cluster diameter," ∼n(-1/3), that interpolates between known atomic and bulk values. In remarkable contrast, the orbital moments do likewise only if the atomic asymptote is exempt. A concept of "primary" and "secondary" (induced) orbital moments is invoked for interpretation. PMID:26374030
The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters
NASA Astrophysics Data System (ADS)
Meyer, Jennifer; Tombers, Matthias; van Wüllen, Christoph; Niedner-Schatteburg, Gereon; Peredkov, Sergey; Eberhardt, Wolfgang; Neeb, Matthias; Palutke, Steffen; Martins, Michael; Wurth, Wilfried
2015-09-01
We present size dependent spin and orbital magnetic moments of cobalt (Con+, 8 ≤ n ≤ 22), iron (Fen+, 7 ≤ n ≤ 17), and nickel cluster (Nin+, 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results. We discuss the application of scaling laws to the size dependent evolution of the spin and orbital magnetic moments per atom in the clusters. We find a spin scaling law "per cluster diameter," ˜n-1/3, that interpolates between known atomic and bulk values. In remarkable contrast, the orbital moments do likewise only if the atomic asymptote is exempt. A concept of "primary" and "secondary" (induced) orbital moments is invoked for interpretation.
Research Update: Plentiful magnetic moments in oxygen deficient SrTiO{sub 3}
Lopez-Bezanilla, Alejandro; Ganesh, P.; Littlewood, Peter B.
2015-10-01
Correlated band theory is employed to investigate the magnetic and electronic properties of different arrangements of oxygen di- and tri-vacancy clusters in SrTiO{sub 3}. Hole and electron doping of oxygen deficient SrTiO{sub 3} yields various degrees of magnetization as a result of the interaction between localized magnetic moments at the defect sites. Different kinds of Ti atomic orbital hybridization are described as a function of the doping level and defect geometry. We find that magnetism in SrTiO{sub 3−δ} is sensitive to the arrangement of neighbouring vacancy sites, charge carrier density, and vacancy-vacancy interaction. Permanent magnetic moments in the absence of vacancy doping electrons are observed. Our description of the charged clusters of oxygen vacancies widens the previous descriptions of mono- and multi-vacancies and points out the importance of the controlled formation at the atomic level of defects for the realization of transition metal oxide based devices with a desirable magnetic performance.
Plentiful magnetic moments in oxygen deficient SrTiO_{3}.
Lopez Bezanilla, Alejandro; Ganesh, P.; Littlewood, Peter B.
2015-10-01
Correlated band theory is employed to investigate the magnetic and electronic properties of different arrangements of oxygen di- and tri-vacancy clusters in SrTiO_{3}. Hole and electron doping of oxygen deficient SrTiO_{3} yields various degrees of magnetization as a result of the interaction between localized magnetic moments at the defected sites. Different kinds of Ti atomic orbital hybridization are described as a function of the doping level and defect geometry. We find that magnetism in SrTiO_{3}-d is sensitive to the arrangement of neighbouring vacancy sites, charge carrier density, and vacancy-vacancy interaction. Permanent magnetic moments in the absence of vacancy doping electrons are observed. Our description of the charged clusters of oxygen vacancies widens the previous descriptions of mono and multi-vacancies and points out the importance of the controlled formation at the atomic level of defects for the realization of transition metal oxide based devices with a desirable magnetic performance.
Afach, S.; Fertl, M.; Franke, B. E-mail: bernhard.lauss@psi.ch; Kirch, K.; Bison, G.; Burri, F.; Chowdhuri, Z.; Daum, M.; Henneck, R.; Lauss, B. E-mail: bernhard.lauss@psi.ch; Meier, M.; Schmidt-Wellenburg, P.; Zsigmond, G.; Bodek, K.; Zejma, J.; Grujic, Z.; Kasprzak, M.; Weis, A.; Hélaine, V.; Koch, H.-C.; and others
2014-08-28
The Surrounding Field Compensation (SFC) system described in this work is installed around the four-layer Mu-metal magnetic shield of the neutron electric dipole moment spectrometer located at the Paul Scherrer Institute. The SFC system reduces the DC component of the external magnetic field by a factor of about 20. Within a control volume of approximately 2.5 m × 2.5 m × 3 m, disturbances of the magnetic field are attenuated by factors of 5–50 at a bandwidth from 10{sup −3} Hz up to 0.5 Hz, which corresponds to integration times longer than several hundreds of seconds and represent the important timescale for the neutron electric dipole moment measurement. These shielding factors apply to random environmental noise from arbitrary sources. This is achieved via a proportional-integral feedback stabilization system that includes a regularized pseudoinverse matrix of proportionality factors which correlates magnetic field changes at all sensor positions to current changes in the SFC coils.
Magnetic moments in a helical edge can make weak correlations seem strong
NASA Astrophysics Data System (ADS)
Väyrynen, Jukka I.; Geissler, Florian; Glazman, Leonid I.
2016-06-01
We study the effect of localized magnetic moments on the conductance of a helical edge. Interaction with a local moment is an effective backscattering mechanism for the edge electrons. We evaluate the resulting differential conductance as a function of temperature T and applied bias V for any value of V /T . Backscattering off magnetic moments, combined with the weak repulsion between the edge electrons, results in a power-law temperature and voltage dependence of the conductance; the corresponding small positive exponent is indicative of insulating behavior. Local moments may naturally appear due to charge disorder in a narrow-gap semiconductor. Our results provide an alternative interpretation of the recent experiment by Li et al. [Phys. Rev. Lett. 115, 136804 (2015)], 10.1103/PhysRevLett.115.136804 where a power-law suppression of the conductance was attributed to strong electron repulsion within the edge, with the value of Luttinger-liquid parameter K fine tuned close to 1 /4 .
Experimental evidence of Cr magnetic moments at low temperature in Cr2A(A=Al, Ge)C.
Jaouen, M; Bugnet, M; Jaouen, N; Ohresser, P; Mauchamp, V; Cabioc'h, T; Rogalev, A
2014-04-30
From x-ray magnetic circular dichroism experiments performed at low temperature on Cr2AlC and Cr2GeC thin films, it is evidenced that Cr atoms carry a net magnetic moment in these ternary phases. It is shown that the Cr magnetization of the Al-based compound nearly vanished at 100 K in agreement with what has been recently observed on bulk. X-ray linear dichroism measurements performed at various angles of incidence and temperatures clearly demonstrate the existence of a charge ordering along the c axis of the structure of Cr2AlC. All these experimental observations support, in part, theoretical calculations claiming that Cr dd correlations have to be considered to correctly describe the structure and properties of these Cr-based ternary phases. PMID:24721758
Orgassa, D.; Fujiwara, H.; Schulthess, T. C.; Butler, W. H.
2000-05-01
Using half-metallic ferromagnets in spin-dependent devices, like spin valves and ferromagnetic tunnel junctions, is expected to increase the device performance. However, using the half-metallic ferromagnet NiMnSb in such devices led to much less than ideal results. One of the possible sources for this behavior is atomic disorder. First-principles calculations of the influence of atomic disorder on the electronic structure of NiMnSb underline the sensitivity of half-metallic properties in NiMnSb to atomic disorder. In this article, we report on the disorder dependence of the total magnetic moment calculated by applying the layer Korringa-Kohn-Rostoker method in conjunction with the coherent potential approximation. We consider the following types of disorder: (1) intermixing of Ni and Mn, (2) partial occupancy of a normally vacant lattice site by Ni and Mn, and (3) partial occupancy of this site by Mn and Sb. In all cases the composition is kept stoichiometric. All three types of disorder decrease the moment monotonically with increasing disorder levels. For the experimentally seen disorder of 5% Mn and 5% Sb on the normally vacant lattice site, the total moment is decreased by 4.1%. The results suggest that precise measurement of the saturation magnetization of NiMnSb thin films can give information on the disorder. (c) 2000 American Institute of Physics.
Zhou, X; Ma, L; Shi, Z; Fan, W J; Evans, R F L; Zheng, Jian-Guo; Chantrell, R W; Mangin, S; Zhang, H W; Zhou, S M
2015-01-01
In this work, disordered-IrMn3/insulating-Y3Fe5O12 exchange-biased bilayers are studied. The behavior of the net magnetic moment ΔmAFM in the antiferromagnet is directly probed by anomalous and planar Hall effects, and anisotropic magnetoresistance. The ΔmAFM is proved to come from the interfacial uncompensated magnetic moment. We demonstrate that the exchange bias and rotational hysteresis loss are induced by partial rotation and irreversible switching of the ΔmAFM. In the athermal training effect, the state of the ΔmAFM cannot be recovered after one cycle of hysteresis loop. This work highlights the fundamental role of the ΔmAFM in the exchange bias and facilitates the manipulation of antiferromagnetic spintronic devices.
NASA Astrophysics Data System (ADS)
Hamada, Shoji; Yamamoto, Osamu; Kobayashi, Tetsuo
This paper presents a generalized equivalent multipole-moment method for calculating three-dimensional Laplacian fields in multi-spherical system. The Greengard & Rokhlin's M2M, M2L, and L2L formulae enable the multipole-moment method to calculate the fields in general arrangement of multi-spheres, which involve exclusive and multi-layered spherical arrangement. We applied this method to electric field calculation in biological structures induced by ELF magnetic fields. The induced electric fields in a three eccentric and exclusive spheres system, which models human head with two eyeballs, are calculated under the application of homogeneous and magnetic-dipole fields. The validity of this method is successfully confirmed by comparing the calculated fields with those by the fast-multipole surface-charge-simulation method.
Orbital magnetic moment and extrinsic spin Hall effect for iron impurities in gold
NASA Astrophysics Data System (ADS)
Shick, Alexander B.; Kolorenč, Jindřich; Janiš, Václav; Lichtenstein, Alexander I.
2011-09-01
We report electronic structure calculations of an iron impurity in a gold host. The spin, orbital, and dipole magnetic moments were investigated using the local density approximation (LDA) + U correlated band theory. We show that the around-mean-field LDA + U reproduces the x-ray magnetic circular dichroism (XMCD) experimental data well and does not lead to the formation of a large orbital moment on the Fe atom. Furthermore, exact diagonalization of the multiorbital Anderson impurity model with the full Coulomb interaction matrix and the spin-orbit coupling is performed in order to estimate the spin Hall angle. The obtained value γS≈0.025 suggests that there is no giant extrinsic spin Hall effect due to scattering on iron impurities in gold.
Neutrino Scattering on Atomic Electrons in Searches for the Neutrino Magnetic Moment
Voloshin, M. B.
2010-11-12
The scattering of a neutrino on atomic electrons is considered in the situation where the energy transferred to the electrons is comparable to the characteristic atomic energies, as relevant to the current experimental search for the neutrino magnetic moment. The process is induced by the standard electroweak interaction as well as by the possible neutrino magnetic moment. Quantum-mechanical sum rules are derived for the inclusive cross section at a fixed energy deposited in the atomic system, and it is shown that the differential over the energy transfer cross section is given, modulo very small corrections, by the same expression as for free electrons, once all possible final states of the electronic system are taken into account. Thus, the atomic effects effectively cancel in the inclusive process.
Zhou, X.; Ma, L.; Shi, Z.; Fan, W. J.; Evans, R. F. L.; Zheng, Jian-Guo; Chantrell, R. W.; Mangin, S.; Zhang, H. W.; Zhou, S. M.
2015-01-01
In this work, disordered-IrMn3/insulating-Y3Fe5O12 exchange-biased bilayers are studied. The behavior of the net magnetic moment ΔmAFM in the antiferromagnet is directly probed by anomalous and planar Hall effects, and anisotropic magnetoresistance. The ΔmAFM is proved to come from the interfacial uncompensated magnetic moment. We demonstrate that the exchange bias and rotational hysteresis loss are induced by partial rotation and irreversible switching of the ΔmAFM. In the athermal training effect, the state of the ΔmAFM cannot be recovered after one cycle of hysteresis loop. This work highlights the fundamental role of the ΔmAFM in the exchange bias and facilitates the manipulation of antiferromagnetic spintronic devices. PMID:25777540
A Procedure for Accurately Measuring the Shaker Overturning Moment During Random Vibration Tests
NASA Technical Reports Server (NTRS)
Nayeri, Reza D.
2011-01-01
Motivation: For large system level random vibration tests, there may be some concerns about the shaker's capability for the overturning moment. It is the test conductor's responsibility to predict and monitor the overturning moment during random vibration tests. If the predicted moment is close to the shaker's capability, test conductor must measure the instantaneous moment at low levels and extrapolate to higher levels. That data will be used to decide whether it is safe to proceed to the next test level. Challenge: Kistler analog formulation for computing the real-time moment is only applicable to very limited cases in which we have 3 or 4 load cells installed at shaker interface with hardware. Approach: To overcome that limitation, a simple procedure was developed for computing the overturning moment time histories using the measured time histories of the individual load cells.
1986-12-01
This report covers the deliberations of the participants the workshop and some subsequent contributions. Section III, the report of the rotating coil group, includes a summary table of the major measuring systems in use today, with separate sections on each. Section IV is the summary report of the group that addressed other measuring techniques. Because one of the limits of all the techniques being considered is electronic data acquisition, Section V addresses this topic. A set of issues relevant to magnetic field measurements of SSC dipoles was raised and addressed during the workshop. These are included as Section VI. Section VII includes a complete list of attendees with their addresses and a separate list of the members of the two working groups.
Rotating effects on the Landau quantization for an atom with a magnetic quadrupole moment.
Fonseca, I C; Bakke, K
2016-01-01
Based on the single particle approximation [Dmitriev et al., Phys. Rev. C 50, 2358 (1994) and C.-C. Chen, Phys. Rev. A 51, 2611 (1995)], the Landau quantization associated with an atom with a magnetic quadrupole moment is introduced, and then, rotating effects on this analogue of the Landau quantization is investigated. It is shown that rotating effects can modify the cyclotron frequency and breaks the degeneracy of the analogue of the Landau levels.
Leading-order hadronic contributions to the electron and tau anomalous magnetic moments
NASA Astrophysics Data System (ADS)
Burger, Florian; Jansen, Karl; Petschlies, Marcus; Pientka, Grit
2016-08-01
The leading hadronic contributions to the anomalous magnetic moments of the electron and the τ -lepton are determined by a four-flavour lattice QCD computation with twisted mass fermions. The results presented are based on the quark-connected contribution to the hadronic vacuum polarisation function. The continuum limit is taken and systematic uncertainties are quantified. Full agreement with results obtained by phenomenological analyses is found.
Hyperfine field of einsteinium in iron and nuclear magnetic moment of Es254
NASA Astrophysics Data System (ADS)
Severijns, N.; Belyaev, A. A.; Erzinkyan, A. L.; Eversheim, P.-D.; Filimonov, V. T.; Golovko, V. V.; Gurevich, G. M.; Herzog, P.; Kraev, I. S.; Lukhanin, A. A.; Noga, V. I.; Parfenova, V. P.; Phalet, T.; Rusakov, A. V.; Tandecki, M.; Toporov, Yu. G.; Tramm, C.; Traykov, E.; Gorp, S. Van; Vyachin, V. N.; Wauters, F.; Zákoucký, D.; Zotov, E.
2009-06-01
The angular distributions of γ rays and α particles from oriented Bk250, Es253,254, and Fm255 nuclei were investigated to extract hyperfine interaction information for these actinide impurities in an iron host lattice. The hyperfine field of einsteinium in iron was found to be |Bhf(EsFe̲|)=396(32) T. With this value the magnetic moment of Es254 was then determined as |μ|=4.35(41)μN.
Magnetization measurements on fine cobalt particles
NASA Astrophysics Data System (ADS)
Respaud, M.; Broto, J. M.; Rakoto, H.; Ousset, J. C.; Osuna, J.; Ould Ely, T.; Amiens, C.; Chaudret, B.; Askenazy, S.
1998-05-01
We measure the magnetization of fine cobalt particles by SQUID and pulsed magnetic fields up to 35 T. These measurements have been made on two samples (C1, C2) with nonagglomerated particles. The analysis of the magnetic meaurements evidences very narrow log-normal size distribution centered around 1.5 nm (≅150 atoms) and 1.9 nm (≅310 atoms) for C1 and C2, respectively. Magnetization at 4.2 K seems to saturate in fields up to 5 T leading to an enhanced mean magnetic moment per atom compared to bulk value (1.72 μB). However, magnetization measurements up to 35 T do not permit to reach saturation, and show a continuous increase of μCo reaching 2.1±0.1 μB (C1) and 1.9±0.1 μB (C2). The effective magnetic anisotropies are found to be larger than those of bulk materials and decrease with increasing particle size. These features are associated with the large influence of the surface atoms.
Leading-order hadronic contributions to the lepton anomalous magnetic moments from the lattice
NASA Astrophysics Data System (ADS)
Burger, Florian; Feng, Xu; Jansen, Karl; Petschlies, Marcus; Pientka, Grit; Renner, Dru B.
2016-04-01
The hadronic leading-order (hlo) contribution to the lepton anomalous magnetic moments alhlo of the Standard Model leptons still accounts for the dominant source of the uncertainty of the Standard Model estimates. We present the results of an investigation of the hadronic leading order anomalous magnetic moments of the electron, muon and tau lepton from first principles in twisted mass lattice QCD. With lattice data for multiple pion masses in the range 230MeV ≲ mPS ≲ 490 MeV, multiple lattice volumes and three lattice spacings we perform the extrapolation to the continuum and to the physical pion mass and check for all systematic uncertainties in the lattice calculation. As a result we calculate alhlo for the three Standard Model leptons with controlled statistical and systematic error in agreement with phenomenological determinations using dispersion relations and experimental data. In addition, we also give a first estimate of the hadronic leading order anomalous magnetic moments from simulations directly at the physical value of the pion mass.
LaCoO3 (LCO) - Dramatic changes in Magnetic Moment in fields to 500T
NASA Astrophysics Data System (ADS)
Lee, Y.; Harmon, B. N.
LCO has attracted great attention over the years (>2000 publications) because of its unusual magnetic properties; although in its ground state at low temperatures it is non-magnetic. A recent experiment[1] in pulsed fields to 500T showed a moment of ~1.3μB above 140T, and above ~270T the magnetization rises, reaching ~3.8μB by 500T. We have performed first principles DFT calculations for LCO in high fields. Our earlier calculations[2] explained the importance of a small rhombohedral distortion in the ground state that leads to a suppression of the 1.3μB moment for fields below ~140T. By allowing fairly large atomic displacements in high fields, moments of ~4μB are predicted. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division under Contract No. DE-AC02-07CH11358.
Electrical tuning of valley magnetic moment through symmetry control in bilayer MoS2
Wu, Sanfeng; Ross, Jason; Liu, G. B.; Aivazian, Grant; Jones, Aaron; Fei, Zaiyao; Zhu, Wenguang; Xiao, Di; Yao, Wang; Cobden, David; Xu, Xiaodong
2013-01-01
Crystal symmetry governs the nature of electronic Bloch states. For example, in the presence of time-reversal symmetry, the orbital magnetic moment and Berry curvature of the Bloch states must vanish unless inversion symmetry is broken1. In certain two-dimensional electron systems such as bilayer graphene, the intrinsic inversion symmetry can be broken simply by applying a perpendicular electric field2,3. In principle, this offers the possibility of switching on/off and continuously tuning the magnetic moment and Berry curvature near the Dirac valleys by reversible electrical control4,5. Here we investigate this possibility using polarization-resolved photoluminescence of bilayer MoS2, which has the same symmetry as bilayer graphene but has a bandgap in the visible spectrum6,7 allowing direct optical probing5,8 12. We find that in bilayer MoS2 the circularly polarized photoluminescence can be continuously tuned from 15% to 15% as a function of gate voltage, whereas in structurally non-centrosymmetric monolayer MoS2 the photoluminescence polarization is gate independent. The observations are well explained as resulting from the continuous variation of orbital magnetic moments between positive and negative values through symmetry control.
The qqqqq components and hidden flavor contributions to the baryon magnetic moments
An, C. S.; Li, Q. B.; Riska, D. O.; Zou, B. S.
2006-11-15
The contributions from the qqqqq components to the magnetic moments of the octet as well as the {delta}{sup ++} and {omega}{sup -} decuplet baryons are calculated for the configurations that are expected to have the lowest energy if the hyperfine interaction depends on both spin and flavor. The contributions from the uu,dd, and the ss components are given separately. It is shown that addition of qqqqq admixtures to the ground state baryons can improve the overall description of the magnetic moments of the baryon octet and decuplet in the quark model without SU(3) flavor symmetry breaking, beyond that of the different constituent masses of the strange and light-flavor quarks. The explicit flavor (and spin) wave functions for all the possible configurations of the qqqqq components with light and strange qq pairs are given for the baryon octet and decuplet. Admixtures of {approx}10% of the qqqqq configuration where the flavor-spin symmetry is [4]{sub FS}[22]{sub F}[22]{sub S}, which is likely to have the lowest energy, in particular reduces the deviation from the empirical values of the magnetic moments {sigma}{sup -} and the {xi}{sup 0} compared with the static qqq quark model.
Regular and chaotic dynamics of a chain of magnetic dipoles with moments of inertia
Shutyi, A. M.
2009-05-15
The nonlinear dynamic modes of a chain of coupled spherical bodies having dipole magnetic moments that are excited by a homogeneous ac magnetic field are studied using numerical analysis. Bifurcation diagrams are constructed and used to find conditions for the presence of several types of regular, chaotic, and quasi-periodic oscillations. The effect of the coupling of dipoles on the excited dynamics of the system is revealed. The specific features of the Poincare time sections are considered for the cases of synchronous chaos with antiphase synchronization and asynchronous chaos. The spectrum of Lyapunov exponents is calculated for the dynamic modes of an individual dipole.
2014-01-01
Co-doped SnO2 thin films were grown by sputtering technique on SiO2/Si(001) substrates at room temperature, and then, thermal treatments with and without an applied magnetic field (HTT) were performed in vacuum at 600°C for 20 min. HTT was applied parallel and perpendicular to the substrate surface. Magnetic M(H) measurements reveal the coexistence of a strong antiferromagnetic (AFM) signal and a ferromagnetic (FM) component. The AFM component has a Néel temperature higher than room temperature, the spin axis lies parallel to the substrate surface, and the highest magnetic moment m =7 μB/Co at. is obtained when HTT is applied parallel to the substrate surface. Our results show an enhancement of FM moment per Co+2 from 0.06 to 0.42 μB/Co at. for the sample on which HTT was applied perpendicular to the surface. The FM order is attributed to the coupling of Co+2 ions through electrons trapped at the site of oxygen vacancies, as described by the bound magnetic polaron model. Our results suggest that FM order is aligned along [101] direction of Co-doped SnO2 nanocrystals, which is proposed to be the easy magnetization axis. PMID:25489286
Magnetic Properties of Strontium Hexaferrite Nanostructures Measured with Magnetic Force Microscopy
Li, Qiang; Song, Jie; Saura-Múzquiz, Matilde; Besenbacher, Flemming; Christensen, Mogens; Dong, Mingdong
2016-01-01
Magnetic property is one of the important properties of nanomaterials. Direct investigation of the magnetic property on the nanoscale is however challenging. Herein we present a quantitative measurement of the magnetic properties including the magnitude and the orientation of the magnetic moment of strontium hexaferrite (SrFe12O19) nanostructures using magnetic force microscopy (MFM) with nanoscale spatial resolution. The measured magnetic moments of the as-synthesized individual SrFe12O19 nanoplatelets are on the order of ~10−16 emu. The MFM measurements further confirm that the magnetic moment of SrFe12O19 nanoplatelets increases with increasing thickness of the nanoplatelet. In addition, the magnetization directions of nanoplatelets can be identified by the contrast of MFM frequency shift. Moreover, MFM frequency imaging clearly reveals the tiny magnetic structures of a compacted SrFe12O19 pellet. This work demonstrates the mesoscopic investigation of the intrinsic magnetic properties of materials has a potential in development of new magnetic nanomaterials in electrical and medical applications. PMID:27174466
Magnetic Properties of Strontium Hexaferrite Nanostructures Measured with Magnetic Force Microscopy.
Li, Qiang; Song, Jie; Saura-Múzquiz, Matilde; Besenbacher, Flemming; Christensen, Mogens; Dong, Mingdong
2016-01-01
Magnetic property is one of the important properties of nanomaterials. Direct investigation of the magnetic property on the nanoscale is however challenging. Herein we present a quantitative measurement of the magnetic properties including the magnitude and the orientation of the magnetic moment of strontium hexaferrite (SrFe12O19) nanostructures using magnetic force microscopy (MFM) with nanoscale spatial resolution. The measured magnetic moments of the as-synthesized individual SrFe12O19 nanoplatelets are on the order of ~10(-16) emu. The MFM measurements further confirm that the magnetic moment of SrFe12O19 nanoplatelets increases with increasing thickness of the nanoplatelet. In addition, the magnetization directions of nanoplatelets can be identified by the contrast of MFM frequency shift. Moreover, MFM frequency imaging clearly reveals the tiny magnetic structures of a compacted SrFe12O19 pellet. This work demonstrates the mesoscopic investigation of the intrinsic magnetic properties of materials has a potential in development of new magnetic nanomaterials in electrical and medical applications. PMID:27174466
Magnetic Properties of Strontium Hexaferrite Nanostructures Measured with Magnetic Force Microscopy
NASA Astrophysics Data System (ADS)
Li, Qiang; Song, Jie; Saura-Múzquiz, Matilde; Besenbacher, Flemming; Christensen, Mogens; Dong, Mingdong
2016-05-01
Magnetic property is one of the important properties of nanomaterials. Direct investigation of the magnetic property on the nanoscale is however challenging. Herein we present a quantitative measurement of the magnetic properties including the magnitude and the orientation of the magnetic moment of strontium hexaferrite (SrFe12O19) nanostructures using magnetic force microscopy (MFM) with nanoscale spatial resolution. The measured magnetic moments of the as-synthesized individual SrFe12O19 nanoplatelets are on the order of ~10-16 emu. The MFM measurements further confirm that the magnetic moment of SrFe12O19 nanoplatelets increases with increasing thickness of the nanoplatelet. In addition, the magnetization directions of nanoplatelets can be identified by the contrast of MFM frequency shift. Moreover, MFM frequency imaging clearly reveals the tiny magnetic structures of a compacted SrFe12O19 pellet. This work demonstrates the mesoscopic investigation of the intrinsic magnetic properties of materials has a potential in development of new magnetic nanomaterials in electrical and medical applications.
Magnetic Properties of Strontium Hexaferrite Nanostructures Measured with Magnetic Force Microscopy
NASA Astrophysics Data System (ADS)
Li, Qiang; Song, Jie; Saura-Múzquiz, Matilde; Besenbacher, Flemming; Christensen, Mogens; Dong, Mingdong
2016-05-01
Magnetic property is one of the important properties of nanomaterials. Direct investigation of the magnetic property on the nanoscale is however challenging. Herein we present a quantitative measurement of the magnetic properties including the magnitude and the orientation of the magnetic moment of strontium hexaferrite (SrFe12O19) nanostructures using magnetic force microscopy (MFM) with nanoscale spatial resolution. The measured magnetic moments of the as-synthesized individual SrFe12O19 nanoplatelets are on the order of ~10‑16 emu. The MFM measurements further confirm that the magnetic moment of SrFe12O19 nanoplatelets increases with increasing thickness of the nanoplatelet. In addition, the magnetization directions of nanoplatelets can be identified by the contrast of MFM frequency shift. Moreover, MFM frequency imaging clearly reveals the tiny magnetic structures of a compacted SrFe12O19 pellet. This work demonstrates the mesoscopic investigation of the intrinsic magnetic properties of materials has a potential in development of new magnetic nanomaterials in electrical and medical applications.
Model-independent inference of neutron star radii from moment of inertia measurements
NASA Astrophysics Data System (ADS)
Raithel, Carolyn A.; Özel, Feryal; Psaltis, Dimitrios
2016-03-01
A precise moment of inertia measurement for PSR J0737-3039A in the double pulsar system is expected within the next five years. We present here a new method of mapping the anticipated measurement of the moment of inertia directly into the neutron star structure. We determine the maximum and minimum values possible for the moment of inertia of a neutron star of a given radius based on physical stability arguments, assuming knowledge of the equation of state only at densities below the nuclear saturation density. If the equation of state is trusted up to the nuclear saturation density, we find that a measurement of the moment of inertia will place absolute bounds on the radius of PSR J0737-3039A to within ±1 km. The resulting combination of moment of inertia, mass, and radius measurements for a single source will allow for new, stringent constraints on the dense-matter equation of state.
Lifting particle coordinate changes of magnetic moment type to Vlasov-Maxwell Hamiltonian dynamics
Morrison, P. J.; Vittot, M.; Guillebon, L. de
2013-03-15
Techniques for coordinate changes that depend on both dependent and independent variables are developed and applied to the Maxwell-Vlasov Hamiltonian theory. Particle coordinate changes with a new velocity variable dependent on the magnetic field, with spatial coordinates unchanged, are lifted to the field theoretic level, by transforming the noncanonical Poisson bracket and Hamiltonian structure of the Vlasov-Maxwell dynamics. Several examples are given including magnetic coordinates, where the velocity is decomposed into components parallel and perpendicular to the local magnetic field, and the case of spherical velocity coordinates. An example of the lifting procedure is performed to obtain a simplified version of gyrokinetics, where the magnetic moment is used as a coordinate and the dynamics is reduced by elimination of the electric field energy in the Hamiltonian.
Ratio of Isoscalar to Isovector Core Polarization Contributions to Magnetic Moments
NASA Astrophysics Data System (ADS)
Robinson, Shadow; Zamick, Larry; Sharon, Yitzhak
2010-11-01
We found that large scale calculations of isoscalar magnetic moments of odd-odd N=Z nuclei yielded results remarkably similar to those of simple single j calculations. To understand why we use a delta interaction times (1+xPs) where Ps is the spin exchange operator, to calculate the ratio IS/IV of the core polarization contributions to the magnetic moments. The spin exchange contributes a factor (1-2x) to this ratio. A popular choice is x=1/3 for which (1-2x) is also 1/3. Another contribution comes from the fact that the coupling of j=l+1/2 to j'=l-1/2 via the magnetic moment operator is proportional to (gs-gl). The IS values are gl=0.5 gs=0.88; the IV values are 0.5 and 4.71. This yields a (gs-gl) ratio of 0.09 which together with the 1/3 from spin exchange tells us that the isoscalar core polarization is a mere 3% of isovector. If we further divide by single j values to get effective charge corrections then the ration IS/IV ends up being 0.06 (or 6%). We thus gain understanding of the resuts in ref [1] of the near equality of large scale and single j results for IS moments.[4pt] [1] S.Yeager, S.J.Q. Robinson, L.Zamick and Y.Y.Sharon, EPL 88, 52001 (2009)
Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; Hjörvarsson, Björgvin; Ito, Yasuo; J. Zaluzec, Nestor; Leifer, Klaus
2015-08-17
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.
Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; Hjörvarsson, Björgvin; Ito, Yasuo; J. Zaluzec, Nestor; Leifer, Klaus
2015-01-01
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features. PMID:26278134
Out-of-Plane Magnetic Moment and Lattice Distortion in Sputtered Ge Added Fe3O4 Thin Film.
Watanabe, Masato; Abe, Seishi
2016-03-01
Fe3O4 has been known to have attractive physical properties for spintronic applications such as half-metallicity, however, its complicated magnetism has yet to be elucidated fully. We investigated the sputtered polycrystalline Fe3O4 thin film in which Ge was added for stabilization of the spinal structure. From X-ray photoelectron and Raman spectroscopies, major part of added Ge is found to be quadrivalent and considered to be incorporated in the spinel structure. Out-of-plane alignment of the local moment was confirmed by conversion electron Mössbauer spectroscopy and magnetization measurements with an applied field up to 70 kOe also support it. The Pawley refinement of the X-ray diffraction profile with a series of possible space groups in the spinel structure suggests that the crystal symmetry is reduced from cubic to tetragonal or orthorhombic spinels with (100) or (010) strains up to -0.231%. The uniaxial anisotropy constants K(u) for the tetragonally distorted cases estimated from the evaluated strains and the ab-initio calculation were found to be around 1.05 x 10(6) erg/cm3. We consider that the magnetic anisotropy induced by the lattice distortion contributes to the out-of-plane alignment of local moments in addition to the previously reported effect by the exchange coupling across crystallographic defects of the antiphase boundaries. PMID:27455663
NASA Astrophysics Data System (ADS)
Frömmgen, Nadja; Balabanski, Dimiter L.; Bissell, Mark L.; Bieroń, Jacek; Blaum, Klaus; Cheal, Bradley; Flanagan, Kieran; Fritzsche, Stephan; Geppert, Christopher; Hammen, Michael; Kowalska, Magdalena; Kreim, Kim; Krieger, Andreas; Neugart, Rainer; Neyens, Gerda; Rajabali, Mustafa M.; Nörtershäuser, Wilfried; Papuga, Jasna; Yordanov, Deyan T.
2015-06-01
Hyperfine structure A and B factors of the atomic 5 s5 p 3P2 → 5 s6 s 3S1 transition are determined from collinear laser spectroscopy data of 107-123Cd and 111 m-123 m Cd. Nuclear magnetic moments and electric quadrupole moments are extracted using reference dipole moments and calculated electric field gradients, respectively. The hyperfine structure anomaly for isotopes with s 1/2 and d 5/2 nuclear ground states and isomeric h 11/2 states is evaluated and a linear relationship is observed for all nuclear states except s 1/2. This corresponds to the Moskowitz-Lombardi rule that was established in the mercury region of the nuclear chart but in the case of cadmium the slope is distinctively smaller than for mercury. In total four atomic and ionic levels were analyzed and all of them exhibit a similar behaviour. The electric field gradient for the atomic 5 s5 p 3P2 level is derived from multi-configuration Dirac-Hartree-Fock calculations in order to evaluate the spectroscopic nuclear quadrupole moments. The results are consistent with those obtained in an ionic transition and based on a similar calculation.
NASA Astrophysics Data System (ADS)
Ferrer, E. J.; de la Incera, V.; Paret, D. Manreza; Martínez, A. Pérez; Sanchez, A.
2015-04-01
We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EOS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (e B >m2 ), the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EOS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EOS at any field value.
Switchable magnetic moment in cobalt-doped graphene bilayer on Cu(111): An ab initio study
NASA Astrophysics Data System (ADS)
Souza, Everson S.; Scopel, Wanderlã L.; Miwa, R. H.
2016-06-01
In this work, we have performed an ab initio theoretical investigation of substitutional cobalt atoms in the graphene bilayer supported on the Cu(111) surface (Co/GBL/Cu). Initially, we examined the separated systems, namely, graphene bilayer adsorbed on Cu(111) (GBL/Cu) and a free standing Co-doped GBL (Co/GBL). In the former system, the GBL becomes n -type doped, where we map the net electronic charge density distribution along the GBL-Cu(111) interface. The substitutional Co atom in Co/GBL lies between the graphene layers, and present a net magnetic moment mostly due to the unpaired Co-3 dz2 electrons. In Co/GBL/Cu, we found that the Cu(111) substrate rules (i) the energetic stability, and (ii) the magnetic properties of substitutional Co atoms in the graphene bilayer. In (i), the substitutional Co atom becomes energetically more stable lying on the GBL surface, and in (ii), the magnetic moment of Co/GBL has been quenched due to the Cu(111) → Co/GBL electronic charge transfer. We verify that such a charge transfer can be tuned upon the application of an external electric field, and thus mediated by a suitable change on the electronic occupation of the Co-dz2 orbitals, we found a way to switch-on and -off the magnetization of the Co-doped GBL adsorbed on the Cu(111) surface.
Remote sensing of the magnetic moment of uranus: predictions for voyager.
Hill, T W; Dessler, A J
1985-03-22
Power is supplied to a planet's magnetosphere from the kinetic energy of planetary spin and the energy flux of the impinging solar wind. A fraction of this power is available to drive numerous observable phenomena, such as polar auroras and planetary radio emissions. In this report our present understanding of these power transfer mechanisms is applied to Uranus to make specific predictions of the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and ultraviolet spectrometer (UVS) instruments aboard the Voyager spacecraft before its encounter with Uranus at the end of January 1986. The power available for these two phenomena is (among other factors) a function of the magnetic moment of Uranus. The date of earliest detectability also depends on whether the predominant power source for the magnetosphere is planetary spin or solar wind. The magnetic moment of Uranus is derived for each power source as a function of the date of first detection of radio emissions by the PRA instrument or auroral emissions by the UVS instrument. If we accept the interpretation of ultraviolet observations now available from the Earth-orbiting International Ultraviolet Explorer satellite, Uranus has a surface magnetic field of at least 0.6 gauss, and more probably several gauss, making it the largest or second-largest planetary magnetic field in the solar system. PMID:17777779
Remote sensing of the magnetic moment of uranus: predictions for voyager.
Hill, T W; Dessler, A J
1985-03-22
Power is supplied to a planet's magnetosphere from the kinetic energy of planetary spin and the energy flux of the impinging solar wind. A fraction of this power is available to drive numerous observable phenomena, such as polar auroras and planetary radio emissions. In this report our present understanding of these power transfer mechanisms is applied to Uranus to make specific predictions of the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and ultraviolet spectrometer (UVS) instruments aboard the Voyager spacecraft before its encounter with Uranus at the end of January 1986. The power available for these two phenomena is (among other factors) a function of the magnetic moment of Uranus. The date of earliest detectability also depends on whether the predominant power source for the magnetosphere is planetary spin or solar wind. The magnetic moment of Uranus is derived for each power source as a function of the date of first detection of radio emissions by the PRA instrument or auroral emissions by the UVS instrument. If we accept the interpretation of ultraviolet observations now available from the Earth-orbiting International Ultraviolet Explorer satellite, Uranus has a surface magnetic field of at least 0.6 gauss, and more probably several gauss, making it the largest or second-largest planetary magnetic field in the solar system.
Nd-doped ZnO monolayer: High Curie temperature and large magnetic moment
NASA Astrophysics Data System (ADS)
Tan, Changlong; Sun, Dan; Zhou, Long; Tian, Xiaohua; Huang, Yuewu
2016-10-01
We performed first-principles calculations within density-functional theory to study the structural, electronic, and magnetic properties of Nd-doped ZnO monolayer. The calculated results reveal that Nd-doped ZnO monolayer exhibits stable room temperature ferromagnetism with a large saturation magnetic moment of 3.99 μB per unit in ZnO monolayer. The magnetic property is contributed to the localized f sates of Nd atoms. When two Zn atoms are substituted by two Nd dopants, they tend to form ferromagnetic (FM) coupling and the estimated Curie temperature is higher than room temperature. More interesting, the impurity bands appear within the band gap of ZnO monolayer due to the introduction of Nd dopant. Our results may provide a reference for modifying the material property of ZnO monolayer and are promising as nanoscale building block in spintronic devices.
Itinerancy-enhanced quantum fluctuation of magnetic moments in iron-based superconductors.
Tam, Yu-Ting; Yao, Dao-Xin; Ku, Wei
2015-09-11
We investigate the influence of itinerant carriers on the dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom. Surprisingly, against the common lore, instead of enhancing the (π,0) order, itinerant carriers with well-nested Fermi surfaces are found to induce a significant amount of spatial and temporal quantum fluctuation that leads to the observed small ordered moment. Interestingly, the underlying mechanism is shown to be an intrapocket nesting-associated long-range coupling rather than the previously believed ferromagnetic double-exchange effect. This challenges the validity of ferromagnetically compensated first-neighbor coupling reported from short-range fitting to the experimental dispersion, which turns out to result instead from the ferro-orbital order that is also found instrumental in stabilizing the magnetic order. PMID:26406850
Itinerancy enhanced quantum fluctuation of magnetic moments in iron-based superconductors
Tam, Yu -T.; Ku, W.; Yao, D. -X.
2015-09-10
We investigate the influence of itinerant carriers on dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom. Surprisingly against the common lore, instead of enhancing the (π,0) order, itinerant carriers with well nested Fermi surfaces is found to induce significant amount of spatial and temporal quantum fluctuation that leads to the observed small ordered moment. Interestingly, the underlying mechanism is shown to be intra-pocket nesting-associated long-range coupling, rather than the previously believed ferromagnetic double-exchange effect. This challenges the validity of ferromagnetically compensated first-neighbor coupling reported from short-range fitting to the experimental dispersion, which turns out to result instead from the ferro-orbital order that is also found instrumental in stabilizing the magnetic order.
Itinerancy enhanced quantum fluctuation of magnetic moments in iron-based superconductors
Tam, Yu -T.; Ku, W.; Yao, D. -X.
2015-09-10
We investigate the influence of itinerant carriers on dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom. Surprisingly against the common lore, instead of enhancing the (π,0) order, itinerant carriers with well nested Fermi surfaces is found to induce significant amount of spatial and temporal quantum fluctuation that leads to the observed small ordered moment. Interestingly, the underlying mechanism is shown to be intra-pocket nesting-associated long-range coupling, rather than the previously believed ferromagnetic double-exchange effect. This challenges the validity of ferromagnetically compensated first-neighbor couplingmore » reported from short-range fitting to the experimental dispersion, which turns out to result instead from the ferro-orbital order that is also found instrumental in stabilizing the magnetic order.« less
Thersleff, Thomas; Rusz, Jan; Rubino, Stefano; Hjörvarsson, Björgvin; Ito, Yasuo; J. Zaluzec, Nestor; Leifer, Klaus
2015-08-17
Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magneticmore » orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.« less
NMR absolute shielding scale and nuclear magnetic dipole moment of (207)Pb.
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. PMID:27265668
Effect of core polarization on magnetic dipole moments in deformed odd-mass nuclei
NASA Astrophysics Data System (ADS)
Bonneau, L.; Minkov, N.; Duc, Dao Duy; Quentin, P.; Bartel, J.
2015-05-01
Magnetic properties of deformed odd-mass nuclei are studied within a nonrelativistic mean-field-plus-pairing approach, namely the Skyrme-Hartree-Fock-BCS approach with self-consistent blocking. For an odd number of nucleons these approaches lead to the breaking of the time-reversal invariance. The deviation from the Schmidt values of the isoscalar magnetic dipole moment is known to result from a subtle balance between core-polarization effects and meson-exchange current effects. However, the former are usually calculated in the random phase approximation without time-reversal symmetry breaking at the mean-field level. In this work we show that if one takes into account this symmetry breaking already in the mean-field solution, the correction from core polarization yields a significant contribution to the empirical quenching of the spin gyromagnetic ratios as compared to the free values in deformed odd-mass nuclei. Moreover, we calculate magnetic dipole moments in the Bohr and Mottelson unified-model description with self-consistent blocked mean-field intrinsic states. The obtained results in the A ˜100 and A ˜180 mass regions as well as for three actinide nuclei compare favorably with experimental data.
Multiferroicity and spiral magnetism in FeVO{sub 4} with quenched Fe orbital moments
Daoud-Aladine, A.; Chapon, L. C.; Kundys, B.; Martin, C.; Simon, C.; Radaelli, P. G.; Brown, P. J.
2009-12-01
FeVO{sub 4} has been studied by heat capacity, magnetic susceptibility, electric polarization and single-crystal neutron-diffraction experiments. The triclinic crystal structure is made of S-shaped clusters of six Fe{sup 3+} ions, linked by VO{sub 4}{sup 3-} groups. Two long-range magnetic ordering transitions occur at T{sub N1}=22 K and T{sub N2}=15 K. Both magnetic structures are incommensurate and below T{sub N2}, FeVO{sub 4} becomes weakly ferroelectric coincidentally with the loss of the collinearity of the magnetic structure in a very similar fashion than in the classical TbMnO{sub 3} multiferroic material. However we argue that the symmetry considerations and the mechanisms invoked to explain these properties in TbMnO{sub 3} do not straightforwardly apply to FeVO{sub 4}. First, the magnetic structures, even the collinear structure, are all acentric so that ferroelectricity in FeVO{sub 4} is not correlated with the fact magnetic ordering is breaking inversion symmetry. Regarding the mechanism, FeVO{sub 4} has quenched orbital moments that questions the exact role of the spin-orbit interactions.
Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms
Gomez, E.; Aubin, S.; Sprouse, G. D.; Orozco, L. A.; DeMille, D. P.
2007-03-15
Weak interactions within a nucleus generate a nuclear spin dependent, parity-violating electromagnetic moment, the anapole moment. We analyze a method to measure the nuclear anapole moment through the electric dipole transition it induces between hyperfine states of the ground level. The method requires tight confinement of the atoms to position them at the antinode of a standing wave Fabry-Perot cavity driving the anapole-induced microwave E1 transition. We explore the necessary limits in the number of atoms, excitation fields, trap type, interrogation method, and systematic tests necessary for such measurements in francium, the heaviest alkali.
Proposed Experiment for the Measurement of the Anapole Moment in Francium
NASA Astrophysics Data System (ADS)
Galvan, A. Perez; Sheng, D.; Orozco, L. A.
2009-01-01
This article presents a proposal of the FRPNC collaboration for a measurement of the anapole moment of the nucleus of francium using parity non-conservation as the signature in a hyperfine transition.
CryoEDM: A cryogenic experiment to measure the neutron electric dipole moment
NASA Astrophysics Data System (ADS)
van der Grinten, M. G. D.; CryoEDM Collaboration; Balashov, S. N.; Francis, V.; Green, K.; Iaydjiev, P. S.; Ivanov, S. N.; Khazov, A.; Tucker, M. A. H.; Wark, D. L.; Davidson, A.; Hardiman, M.; Harris, P. G.; Katsika, K.; Pendlebury, J. M.; Peeters, S. J. M.; Shiers, D. B.; Smith, P.; Townsley, C.; Wardell, I.; Clarke, C.; Henry, S.; Kraus, H.; McCann, M.; Geltenbort, P.; Yoshiki, Y.
2009-12-01
CryoEDM is an experiment that aims to measure the electric dipole moment (EDM) of the neutron to a precision of 10 -28 e cm. A description of CryoEDM, the apparatus, technologies and commissioning is presented.
Measurement of the Magnet Blocks for SSRF Insertion Devices
He Yongzhou; Zhang Jidong; Zhou Qiaogen; Qian Zhenmei; Li Yang
2010-06-23
Two in-vacuum undulators IVU25s and one elliptically polarized undulator EPU100 have been developed for SSRF. Two IVU25s with the same hybrid design contain about 640 Sm{sub 2}Co{sub 17} magnet blocks and the dimension of blocks is 65 Wx25 Hx9 D. The EPU100 of the APPLE-II type contains about 690 NdFeB magnet blocks with the dimension of 35 Wx35 Hx25 D. This paper describes the magnetic measurements of these magnet blocks with the Helmholtz coil measurement system for IVU25 magnet blocks and the Hall probe measurement system for EPU100 magnet blocks. The measured maximum magnetic moment deviation and the maximum angle deviation are less than {+-}1.0% and 1.1 deg. respectively both for Sm{sub 2}Co{sub 17} blocks and NdFeB blocks and satisfy the specifications of undulators.
Progress Towards a New Measurement of the Electric Dipole Moment of ^199Hg.
NASA Astrophysics Data System (ADS)
Swallows, M. D.; Griffith, W. C.; Heckel, B. R.; Fortson, E. N.; Romalis, M. V.
2007-06-01
We are currently undertaking a four vapor cell search for the permanent electric dipole moment (EDM) of ^199Hg. The existence of a nonzero EDM would imply a source of CP violation beyond the standard model. The present limit on the EDM of ^199 Hg is |dHg| < 2.1 x10-28 ,,, which was established several years ago by our group at the University of Washington. In that experiment, two quartz vapor cells containing polarized Hg vapor were placed in parallel magnetic and anti-parallel electric fields (the use of two cells permitted the removal of common-mode effects), and the spin precession frequency was measured using an optical technique. In our current experiment, two additional cells at zero electric field serve to cancel magnetic gradient noise and to improve limits on systematic effects due to charging and leakage currents. We have recently overcome several systematic issues and begun acquiring data with our upgraded apparatus. To prevent experimenter bias from influencing the data, we have also instituted a blind analysis protocol. The statistical error of the data at the time of this writing was ±0.15x10-28 e cm, and we hope to improve the sensitivity by a further factor of two. We will discuss recent progress and our plans to place improved limits on systematic effects.
Environmental applications of magnetic measurements.
Thompson, R; Stober, J C; Turner, G M; Oldfield, F; Bloemendal, J; Dearing, J A; Rummery, T A
1980-02-01
A wide range of examples of the application of magnetic measurements to environmental studies illustrate the advantages of magnetic techniques over conventional methods. Magnetic measurements, in both the field and the laboratory, are particularly useful for reconnaissance work because of their spee and flexibility, Quantification as well as simple diagnosis of the transformation and movement of magnetic minerals within and between the atmosphere, lithosphere, and hydrosphere is practical. Techniques of investigating intrinsic and mineral magnetic properties, in addition to paleomagnetic remanence, are described in subjects as diverse as meteorology, hydrology, sedimentology, geophysics, and ecology. PMID:17795619
Hyperfine field of einsteinium in iron and nuclear magnetic moment of {sup 254}Es
Severijns, N.; Kraev, I. S.; Phalet, T.; Tandecki, M.; Traykov, E.; Gorp, S. Van; Wauters, F.; Belyaev, A. A.; Lukhanin, A. A.; Noga, V. I.; Erzinkyan, A. L.; Parfenova, V. P.; Eversheim, P.-D.; Herzog, P.; Tramm, C.; Filimonov, V. T.; Toporov, Yu. G.; Zotov, E.; Golovko, V. V.; Gurevich, G. M.
2009-06-15
The angular distributions of {gamma} rays and {alpha} particles from oriented {sup 250}Bk, {sup 253,254}Es, and {sup 255}Fm nuclei were investigated to extract hyperfine interaction information for these actinide impurities in an iron host lattice. The hyperfine field of einsteinium in iron was found to be |B{sub hf}(EsFe{sub lowbar|})=396(32) T. With this value the magnetic moment of {sup 254}Es was then determined as |{mu}|=4.35(41) {mu}{sub N}.
Magnetic moment of the majorana neutrino in the left-right symmetric model
Boyarkin, O. M. Boyarkina, G. G.
2013-04-15
Corrections to the neutrino magnetic dipole moment from the singly charged Higgs bosons h{sup ({+-})} and {delta}-tilde{sup (}{+-}) were calculated within the left-right symmetric model involving Majorana neutrinos. It is shown that, if the h{sup ({+-})} and {delta}-tilde{sup (}{+-}) bosons lie at the electroweak scale, the contributions from Higgs sector are commensurate with the contribution of charged gauge bosons or may even exceed it. The behavior of the neutrino flux inmatter and in amagnetic field was studied. It was found that resonance transitions between light and heavy neutrinos are forbidden.
Blum, Thomas; Chowdhury, Saumitra; Hayakawa, Masashi; Izubuchi, Taku
2015-01-07
The form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in lattice QCD+QED and QED. A non-perturbative treatment of QED is used and is checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed. Statistically significant signals are obtained. Initial results appear promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
Lattice calculation of hadronic light-by-light contribution to the muon anomalous magnetic moment
Blum, Thomas; Christ, Norman; Hayakawa, Masashi; Izubuchi, Taku; Jin, Luchang; Lehner, Christoph
2016-01-12
The quark-connected part of the hadronic light-by-light scattering contribution to the muon’s anomalous magnetic moment is computed using lattice QCD with chiral fermions. Here we report several significant algorithmic improvements and demonstrate their effectiveness through specific calculations which show a reduction in statistical errors by more than an order of magnitude. The most realistic of these calculations is performed with a near-physical 171 MeV pion mass on a (4.6 fm)3 spatial volume using the 323×64 Iwasaki+DSDR gauge ensemble of the RBC/UKQCD Collaboration.
Leading SU(3)-breaking corrections to the baryon magnetic moments in chiral perturbation theory.
Geng, L S; Camalich, J Martin; Alvarez-Ruso, L; Vacas, M J Vicente
2008-11-28
We calculate the baryon magnetic moments using covariant chiral perturbation theory (chiPT) within the extended-on-mass-shell renormalization scheme. By fitting the two available low-energy constants, we improve the Coleman-Glashow description of the data when we include the leading SU(3)-breaking effects coming from the lowest-order loops. This success is in dramatic contrast with previous attempts at the same order using heavy-baryon chiPT and covariant infrared chiPT. We also analyze the source of this improvement with particular attention to the comparison between the covariant results.
A 17 keV neutrino and large magnetic moment solution of the solar neutrino puzzle
NASA Astrophysics Data System (ADS)
Akhmedov, E. Kh.; Senjanovic, G.; Tao, Zhijian; Berezhiani, Z. G.
1992-08-01
Zee-type models with Majorons naturally incorporate the 17 keV neutrino but in their minimal version fail to simultaneously solve the solar neutrino puzzle. If there is a sterile neutrino state, a particularly simple solution is found to the solar neutrino problem, which besides nu(sub 17) predicts a light Zeldovich-Konopinski-Mahmoud neutrino nu(sub light) = nu(sub e) + nu(sub mu)(sup c) with a magnetic moment being easily as large as 10(exp -11)(mu)(sub B) through the Barr-Freire-Zee mechanism.
17 keV neutrino and large magnetic moment solution of the solar neutrino puzzle
NASA Astrophysics Data System (ADS)
Akhmedov, Eugeni Kh.; Berezhiani, Zurab G.; Senjanović, Goran; Tao, Zhijian
1993-01-01
Zee-type models with majorons naturally incorporate the 17 keV neutrino but in their minimal version fail to simultaneously solve the solar neutrino puzzle. If there is a sterile neutrino state, we find a particularly simple solution to the solar neutrino problem, which besides ν17 predicts a light Zeldovich-Konopinski-Mahmoud neutrino νlight = νe + νcμ with a magnetic moment being easily as large as 10 -11μB through the Barr-Freire-Zee mechanism.
Ionization of helium atoms under the effect of the antineutrino magnetic moment
Martemyanov, V. P. Tsinoev, V. G.
2011-12-15
Differential cross sections for inelastic antineutrino interaction with a helium atom are calculated. It is shown that, in the energy-transfer range extending up to 1 keV, the cross sections in question are considerably enhanced in the electromagnetic-interaction channel in relation to the cross sections for elastic scattering on a free electron. Absolute cross-section values are of interest in searches for the antineutrino magnetic moment, provided that its value in Bohr magneton units falls within the range (10{sup -13}-10{sup -12}){sub Micro-Sign B}.
Using baryon octet magnetic moments and masses to fix the pion cloud contribution
Franz L. Gross; Ramalho, Gilberto T. F.; Tsushima, Kazuo
2010-05-12
In this study, using SU(3) symmetry to constrain themore » $$\\pi BB'$$ couplings, assuming SU(3) breaking comes only from one-loop pion cloud contributions, and using the the covariant spectator theory to describe the photon coupling to the quark core, we show how the experimental masses and magnetic moments of the baryon octet can be used to set a model independent constraint on the strength of the pion cloud contributions to the octet, and hence the nucleon, form factors at $Q^2=0$.« less
Using baryon octet magnetic moments and masses to fix the pion cloud contribution
Franz L. Gross; Ramalho, Gilberto T. F.; Tsushima, Kazuo
2010-05-12
In this study, using SU(3) symmetry to constrain the $\\pi BB'$ couplings, assuming SU(3) breaking comes only from one-loop pion cloud contributions, and using the the covariant spectator theory to describe the photon coupling to the quark core, we show how the experimental masses and magnetic moments of the baryon octet can be used to set a model independent constraint on the strength of the pion cloud contributions to the octet, and hence the nucleon, form factors at $Q^2=0$.
Unquenched quark model for baryons: Magnetic moments, spins, and orbital angular momenta
Bijker, R.; Santopinto, E.
2009-12-15
We present an unquenched quark model for baryons in which the effects of the quark-antiquark pairs (uu, dd, and ss) are taken into account in an explicit form via a microscopic, QCD-inspired, quark-antiquark creation mechanism. In the present approach, the contribution of the quark-antiquark pairs can be studied for any inital baryon and for any flavor of the qq pairs. It is shown that, while the inclusion of the qq pairs does not affect the baryon magnetic moments, it leads to a sizable contribution of the orbital angular momentum to the spin of the proton and the {lambda} hyperon.
Remote sensing of the magnetic moment of Uranus - Predictions for Voyager
NASA Astrophysics Data System (ADS)
Hill, T. W.; Dessler, A. J.
1985-03-01
The current understanding of the power transfer mechanisms by which power is supplied to a planet's magnetosphere by the kinetic energy of planetary spin and the energy flux of the impinging solar wind is applied to the case of Uranus, in order to predict the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and UV spectrometer (UVS) instruments of the Voyager spacecraft. The power available for the two energy transfer phenomena cited is a function of Uranus' magnetic moment, which is presently derived for each power source as a function of the date of first detection of radio emissions by the PRA or auroral emissions by the UVS.
Room-temperature ferromagnetism with high magnetic moment in Cu-doped AlN single crystal whiskers
NASA Astrophysics Data System (ADS)
Jiang, Liang-Bao; Liu, Yu; Zuo, Si-Bin; Wang, Wen-Jun
2015-02-01
Ferromagnetism is investigated in high-quality Cu-doped AlN single crystal whiskers. The whiskers exhibit room-temperature ferromagnetism with a magnetic moment close to the results from first-principles calculations. High crystallinity and low Cu concentrations are found to be indispensable for high magnetic moments. The difference between the experimental and theoretical moment values is explored in terms of the influence of nitrogen vacancies. The calculated results demonstrate that nitrogen vacancies can reduce the magnetic moments of Cu atom. Project supported by the National Basic Research Program of China (Grant No. 2013CB932901), the National Natural Science Foundation of China (Grant Nos. 51372267, 51210105026, and 51172270), the Funds from the Chinese Academy of Sciences, the International Centre for Diffraction Data, USA (2013 Ludo Frevel Crystallography Scholarship Award), and the Funds from the Ministry of Education of China (2012 Academic Scholarship Award for Doctoral Candidates).
Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)
NASA Astrophysics Data System (ADS)
White, Benjamin; Yazici, Duygu; Ho, Pei-Chun; Kanchanavatee, Noravee; Pouse, Naveen; Friedman, Aaron; Maple, M. Brian
2015-03-01
Large Ce-Ce distances of 6.7-6.8 Åand weak hybridization between Ce 4 f and itinerant electron states act to promote stable localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd), but also conspire to severely limit the strength of the Ruderman-Kittel-Kasuya-Yosida (RKKY) magnetic exchange interaction that couples them. As a consequence, measurements of electrical resistivity, performed on single-crystalline samples of these new Cd-based compounds down to 0.138 K, were unable to resolve any evidence for magnetic order. In this presentation, we will compare measurements of the physical properties of CeT2Cd20 (T = Ni, Pd) under ambient and applied pressures with the reported properties of the isostructural compounds CeT2X20 (T = transition metal; X = Al, Zn). We will use these comparisons to discuss the interplay of unit cell volume, hybridization, and the RKKY interaction and its role in establishing the ground states of the Ce-based ``1-2-20'' compounds. Sample synthesis and physical properties measurements were supported by the U.S. DOE under Grant No. DE-FG02-04-ER46105. Measurements of electrical resistivity below 1 K were supported by the NSF under Grants No. DMR-1206553 and No. DMR-1104544.
NASA Astrophysics Data System (ADS)
Wang, Liang; Hakim, Ammar H.; Bhattacharjee, A.; Germaschewski, K.
2015-01-01
We introduce an extensible multi-fluid moment model in the context of collisionless magnetic reconnection. This model evolves full Maxwell equations and simultaneously moments of the Vlasov-Maxwell equation for each species in the plasma. Effects like electron inertia and pressure gradient are self-consistently embedded in the resulting multi-fluid moment equations, without the need to explicitly solving a generalized Ohm's law. Two limits of the multi-fluid moment model are discussed, namely, the five-moment limit that evolves a scalar pressures for each species and the ten-moment limit that evolves the full anisotropic, non-gyrotropic pressure tensor for each species. We first demonstrate analytically and numerically that the five-moment model reduces to the widely used Hall magnetohydrodynamics (Hall MHD) model under the assumptions of vanishing electron inertia, infinite speed of light, and quasi-neutrality. Then, we compare ten-moment and fully kinetic particle-in-cell (PIC) simulations of a large scale Harris sheet reconnection problem, where the ten-moment equations are closed with a local linear collisionless approximation for the heat flux. The ten-moment simulation gives reasonable agreement with the PIC results regarding the structures and magnitudes of the electron flows, the polarities and magnitudes of elements of the electron pressure tensor, and the decomposition of the generalized Ohm's law. Possible ways to improve the simple local closure towards a nonlocal fully three-dimensional closure are also discussed.
Wang, Liang Germaschewski, K.; Hakim, Ammar H.; Bhattacharjee, A.
2015-01-15
We introduce an extensible multi-fluid moment model in the context of collisionless magnetic reconnection. This model evolves full Maxwell equations and simultaneously moments of the Vlasov-Maxwell equation for each species in the plasma. Effects like electron inertia and pressure gradient are self-consistently embedded in the resulting multi-fluid moment equations, without the need to explicitly solving a generalized Ohm's law. Two limits of the multi-fluid moment model are discussed, namely, the five-moment limit that evolves a scalar pressures for each species and the ten-moment limit that evolves the full anisotropic, non-gyrotropic pressure tensor for each species. We first demonstrate analytically and numerically that the five-moment model reduces to the widely used Hall magnetohydrodynamics (Hall MHD) model under the assumptions of vanishing electron inertia, infinite speed of light, and quasi-neutrality. Then, we compare ten-moment and fully kinetic particle-in-cell (PIC) simulations of a large scale Harris sheet reconnection problem, where the ten-moment equations are closed with a local linear collisionless approximation for the heat flux. The ten-moment simulation gives reasonable agreement with the PIC results regarding the structures and magnitudes of the electron flows, the polarities and magnitudes of elements of the electron pressure tensor, and the decomposition of the generalized Ohm's law. Possible ways to improve the simple local closure towards a nonlocal fully three-dimensional closure are also discussed.
Increased magnetic moment induced by lattice expansion from α-Fe to α′-Fe{sub 8}N
Dirba, Imants Komissinskiy, Philipp; Alff, Lambert; Gutfleisch, Oliver
2015-05-07
Buffer-free and epitaxial α-Fe and α′-Fe{sub 8}N{sub x} thin films have been grown by RF magnetron sputtering onto MgO (100) substrates. The film thicknesses were determined with high accuracy by evaluating the Kiessig fringes of X-ray reflectometry measurements allowing a precise volume estimation. A gradual increase of the nitrogen content in the plasma led to an expansion of the iron bcc unit cell along the [001] direction resulting finally in a tetragonal distortion of about 10% corresponding to the formation of α′-Fe{sub 8}N. The α-Fe lattice expansion was accompanied by an increase in magnetic moment to 2.61 ± 0.06μ{sub B} per Fe atom and a considerable increase in anisotropy. These experiments show that—without requiring any additional ordering of the nitrogen atoms—the lattice expansion of α-Fe itself is the origin of the increased magnetic moment in α′-Fe{sub 8}N.
Moment enhancement in dilute magnetic semiconductors: MnxSi1-x with x = 0.1%
Shaughnessy, M; Fong, C Y; Snow, R; Liu, K; Pask, J E; Yang, L H
2009-03-12
The experimentally determined magnetic moments/Mn, M, in Mn{sub x}Si{sub 1-x} are considered, with particular attention to the case with 5.0 {micro}{sub B}/Mn, obtained for x = 0.1%. The existing theoretical M values for neutral Mn range from 2.83 to 3.78 {micro}B/Mn. To understand the observed M = 5.0 {micro}{sub B}/Mn, we investigated Mn{sub x}Si{sub 1-x} for a series of Mn concentrations and defect configurations using a first-principles density functional method. We find a structure in which the moment is enhanced. It has 5.0 {micro}B/Mn, the Mn at a substitutional site, and a Si at a second-neighbor interstitial site in a large unit cell. Subsequent analysis shows that the observed large moment can be understood as a consequence of the weakened d-p hybridization resulting from the introduction of the second-neighbor interstitial Si and substantial isolation of the Mn-second-neighbor Si complex at such concentrations.
Vilmercati, Paolo; Fedorov, Alexei; Bondino, Federica; Offi, Francesco; Panaccione, Giancarlo; Lacovig, Paolo; Simonelli, Laura; McGuire, Michael A.; Sefat, Athena S. M.; Mandrus, David; et al
2012-06-15
A direct and element-specific measurement of the local Fe spin moment has been provided by analyzing the Fe 3s core level photoemission spectra in the parent and optimally doped CeFeAsO₁₋xFx (x = 0, 0.11) and Sr(Fe₁₋xCox)2As2 (x = 0, 0.10) pnictides. The rapid time scales of the photoemission process allowed the detection of large local spin moments fluctuating on a 10⁻¹⁵ s time scale in the paramagnetic, antiferromagnetic, and superconducting phases, indicative of the occurrence of ubiquitous strong Hund's magnetic correlations. The magnitude of the spin moment is found to vary significantly among different families, 1.3μB in CeFeAsO and 2.1μBmore » in SrFe₂As₂. Surprisingly, the spin moment is found to decrease considerably in the optimally doped samples, 0.9μB in CeFeAsO₀.₈₉F₀.₁₁ and 1.3μB in Sr(Fe₀.₉Co₀.₁)₂As₂. The strong variation of the spin moment against doping and material type indicates that the spin moments and the motion of itinerant electrons are influenced reciprocally in a self-consistent fashion, reflecting the strong competition between the antiferromagnetic superexchange interaction among the spin moments and the kinetic energy gain of the itinerant electrons in the presence of a strong Hund's coupling. By describing the evolution of the magnetic correlations concomitant with the appearance of superconductivity, these results constitute a fundamental step toward attaining a correct description of the microscopic mechanisms shaping the electronic properties in the pnictides, including magnetism and high-temperature superconductivity.« less
Martin, Joel R.; Latash, Mark L.; Zatsiorsky, Vladimir M.
2011-01-01
Background The purpose of this study was to use magnetic resonance imaging to measure the moment arm of the flexor digitorum superficialis tendon about the metacarpophalangeal joint of the index, middle, ring, and little fingers when the position and force production level of the index finger was altered. A secondary goal was to create regression models using anthropometric data to predict moment arms of the flexor digitorum superficialis about the metacarpophalangeal joint of each finger. Methods The hands of subjects were scanned using a 3.0T magnetic resonance imaging scanner. The metacarpophalangeal joint of the index finger was placed in: flexion, neutral, and extension. For each joint configuration subjects produced no active force (passive condition) and exerted a flexion force to resist a load at the fingertip (active condition). Results The following was found: (1) The moment arm of the flexor digitorum superficialis at the metacarpophalangeal joint of the index finger (a) increased with the joint flexion and stayed unchanged with finger extension; and (b) decreased with the increase of force at the neutral and extended finger postures and did not change at the flexed posture. (2) The moment arms of the flexor digitorum superficialis tendon of the middle, ring, and little fingers (a) did not change when the index metacarpophalangeal joint position changed (p > 0.20); and (b) The moment arms of the middle and little fingers increased when the index finger actively produced force at the flexed metacarpophalangeal joint posture. (4) The moment arms showed a high correlation with anthropometric measurements. Interpretation Moment arms of the flexor digitorum superficialis change due to both changes in joint angle and muscle activation; they scale with various anthropometric measures. PMID:22192658
NASA Astrophysics Data System (ADS)
Sandratskii, L. M.
2015-10-01
We report the first-principles study of the correlated behavior of the magnetic anisotropy energy (MAE) and orbital moment anisotropy (OMA) as the functions of the thickness N of the Fe film. The work is motivated by recent experimental studies combining photoemission, x-ray magnetic circular dichroism, and magnetic anisotropy measurements. In agreement with experiment, the correlated oscillations of MAE (N ) and OMA (N ) are obtained that have their origin in the formation of the 3d quantum well states (QWS) confined in the films. The main contribution to the oscillation amplitude comes from the surface layer. This is an interesting feature of the phenomenon consisting in the peculiar dependence of the physical quantities on the thickness of the film. We demonstrate that the band structure of the bulk Fe does not reflect adequately the properties of the 3d QWS in thin films and, therefore, does not provide the basis for understanding the oscillations of MAE (N ) and OMA (N ) . A detailed point-by-point analysis in the two-dimensional (2D) Brillouin zone (BZ) of the film shows that the contribution of the Γ point, contrary to a rather common expectation, does not play an important role in the formation of the oscillations. Instead, the most important contributions come from a broad region of the 2D BZ distant from the center of the BZ. Combining symmetry arguments and direct calculations we show that orbital moments of the electronic states possess nonzero transverse components orthogonal to the direction of the spin magnetization. The account for this feature is crucial in the point-by-point analysis of the OMA. On the basis of the calculations for noncollinear spin configurations we suggest interpretations of two interesting experimental findings: fast temperature decay of the oscillation amplitude in MAE (N ) and unexpectedly strong spin mixing of the initial states of the photoemission process.
An improved method in the measurement of the moment of inertia
NASA Astrophysics Data System (ADS)
Peng, Jun; Zhang, Li
2016-06-01
The moment of inertia calibration system is developed by Changcheng Institute of Metrology and Measurement (CIMM). Rotation table - torsional spring system is used to generate angular vibration, and laser vibrometer is used to measure rotational angle and the vibration period. The object to be measured is mounted on the top of the rotation table. The air-bearing system is elaborately manufactured which reduce the friction of the angular movement and increase measurement accuracy. Heterodyne laser interferometer collaborates with column diffraction grating is used in the measurement of angular movement. Experiment shows the method of measuring oscillating angle and period introduced in this paper is stable and the time resolution is high. When the air damping effect can't be neglected in moment of inertia measurement, the periodic waveform area ratio method is introduced to calculate damping ratio and obtain the moment of inertia.
Concentration dependence of magnetic moment in Ce1-xFexO2
NASA Astrophysics Data System (ADS)
Beausoleil, Geoffrey L.; Thurber, Aaron; Rao, S. S.; Alanko, Gordon; Hanna, C. B.; Punnoose, Alex
2012-04-01
In this study, we examined the impact of iron doping on the structural, chemical, and magnetic properties of ceria (Ce1-xFexO2). Samples were produced in triplicate through a coprecipitation approach in a forced hydrolysis synthesis that yielded consistently sized nanocrystals using three different cerium precursors: cerium chloride, cerium ammonium nitrate, and cerium nitrate. Particles were characterized by x ray diffraction (XRD), x ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) spectroscopy, and vibrating sample magnetometry (VSM). XPS and EPR data shows iron to be in the Fe3+ state and confirms the nominal dopant concentration. The moment per Fe ion found was largest at the lowest dopant concentrations, and quickly decreased as the concentration was increased. We used XPS to estimate the Ce3+/Ce4+ ratio and observed a linear relation between the saturation magnetization and the Ce3+/Ce4+ ratio.
Muon anomalous magnetic moment and penguin loops in warped extra dimensions
NASA Astrophysics Data System (ADS)
Beneke, M.; Moch, P.; Rohrwild, J.
2014-08-01
We describe the computation of the one-loop muon anomalous magnetic moment and radiative penguin transitions in the minimal and custodially protected Randall-Sundrum model. A fully five-dimensional (5D) framework is employed to match the 5D theory onto the Standard Model extended by dimension-six operators. The additional contribution to the anomalous magnetic moment from the gauge-boson exchange contributions is $Δ aμ ≈ 8.8 (27.2) ḑot 10-11 × (1 TeV/T)2 ,$ where the first (second) number refers to the minimal (custodially-protected) model. Here 1/T denotes the location of the TeV brane in conformal coordinates, and is related to the mass of the lowest gauge-boson KK excitation by MKK≈2.35T. We also determine the Higgs-exchange contribution, which depends on the 5D Yukawa structure and the precise interpretation of the localization of the Higgs field near or at the TeV brane.
NASA Astrophysics Data System (ADS)
Matsumoto, Munehisa; Banerjee, Rudra; Staunton, Julie B.
2014-08-01
Temperature dependence of the magnetocrystalline anisotropy energy and magnetization of the prototypical rare-earth magnet YCo5 is calculated from first principles, utilizing the relativistic disordered local-moment approach. We discuss a strategy to enhance the finite-temperature anisotropy field by hole doping, paving the way for an improvement of the coercivity near room temperature or higher.
NASA Astrophysics Data System (ADS)
Okabayashi, Jun; Sukegawa, Hiroaki; Wen, Zhenchao; Inomata, Koichiro; Mitani, Seiji
2013-09-01
Perpendicular magnetic anisotropy (PMA) in Heusler alloy Co2FeAl thin films sharing an interface with a MgO layer is investigated by angular-dependent x-ray magnetic circular dichroism. Orbital and spin magnetic moments are deduced separately for Fe and Co 3d electrons. In addition, the PMA energies are estimated using the orbital magnetic moments parallel and perpendicular to the film surfaces. We found that PMA in Co2FeAl is determined mainly by the contribution of Fe atoms with large orbital magnetic moments, which are enhanced at the interface between Co2FeAl and MgO. Furthermore, element specific magnetization curves of Fe and Co are found to be similar, suggesting the existence of ferromagnetic coupling between Fe and Co PMA directions.
Measurements of magnetic field alignment
Kuchnir, M.; Schmidt, E.E.
1987-11-06
The procedure for installing Superconducting Super Collider (SSC) dipoles in their respective cryostats involves aligning the average direction of their field with the vertical to an accuracy of 0.5 mrad. The equipment developed for carrying on these measurements is described and the measurements performed on the first few prototypes SSC magnets are presented. The field angle as a function of position in these 16.6 m long magnets is a characteristic of the individual magnet with possible feedback information to its manufacturing procedure. A comparison of this vertical alignment characteristic with a magnetic field intensity (by NMR) characteristic for one of the prototypes is also presented. 5 refs., 7 figs.
The investigation of giant magnetic moment in ultrathin Fe3O4 films
NASA Astrophysics Data System (ADS)
Guan, Xiaofen; Zhou, Guowei; Xue, Wuhong; Quan, Zhiyong; Xu, Xiaohong
2016-03-01
The magnetic and transport properties of Fe3O4 films with a series of thicknesses are investigated. For the films with thickness below 15 nm, the saturation magnetization (Ms) increases and the coercivity decreases with the decrease in films' thickness. The Ms of 3 nm Fe3O4 film is dramatically increased to 1017 emu/cm3. As for films' thickness more than 15 nm, Ms is tending to be close to the Fe3O4 bulk value. Furthermore, the Verwey transition temperature (Tv) is visible for all the films, but suppressed for 3 nm film. We also find that the ρ of 3 nm film is the highest of all the films. The suppressed Tv and high ρ may be related to the islands morphology in 3 nm film. To study the structure, magnetic, and transport properties of the Fe3O4 films, we propose that the giant magnetic moment most likely comes from the spin of Fe ions in the tetrahedron site switching parallel to the Fe ions in the octahedron site at the surface, interface, and grain boundaries. The above results are of great significance and also provide a promising future for either device applications or fundamental research.
Rashba Interaction and Local Magnetic Moments in a Graphene-BN Heterostructure Intercalated with Au
NASA Astrophysics Data System (ADS)
O'Farrell, E. C. T.; Tan, J. Y.; Yeo, Y.; Koon, G. K. W.; Ã-zyilmaz, B.; Watanabe, K.; Taniguchi, T.
2016-08-01
We intercalate a van der Waals heterostructure of graphene and hexagonal boron nitride with Au, by encapsulation, and show that the Au at the interface is two dimensional. Charge transfer upon current annealing indicates the redistribution of the Au and induces splitting of the graphene band structure. The effect of an in-plane magnetic field confirms that the splitting is due to spin splitting and that the spin polarization is in the plane, characteristic of a Rashba interaction with a magnitude of approximately 25 meV. Consistent with the presence of an intrinsic interfacial electric field we show that the splitting can be enhanced by an applied displacement field in dual gated samples. A giant negative magnetoresistance, up to 75%, and a field induced anomalous Hall effect at magnetic fields <1 T are observed. These demonstrate that the hybridized Au has a magnetic moment and suggests the proximity to the formation of a collective magnetic phase. These effects persist close to room temperature.
Rashba Interaction and Local Magnetic Moments in a Graphene-BN Heterostructure Intercalated with Au.
O'Farrell, E C T; Tan, J Y; Yeo, Y; Koon, G K W; Özyilmaz, B; Watanabe, K; Taniguchi, T
2016-08-12
We intercalate a van der Waals heterostructure of graphene and hexagonal boron nitride with Au, by encapsulation, and show that the Au at the interface is two dimensional. Charge transfer upon current annealing indicates the redistribution of the Au and induces splitting of the graphene band structure. The effect of an in-plane magnetic field confirms that the splitting is due to spin splitting and that the spin polarization is in the plane, characteristic of a Rashba interaction with a magnitude of approximately 25 meV. Consistent with the presence of an intrinsic interfacial electric field we show that the splitting can be enhanced by an applied displacement field in dual gated samples. A giant negative magnetoresistance, up to 75%, and a field induced anomalous Hall effect at magnetic fields <1 T are observed. These demonstrate that the hybridized Au has a magnetic moment and suggests the proximity to the formation of a collective magnetic phase. These effects persist close to room temperature. PMID:27563982
NASA Astrophysics Data System (ADS)
Slim, J.; Gebel, R.; Heberling, D.; Hinder, F.; Hölscher, D.; Lehrach, A.; Lorentz, B.; Mey, S.; Nass, A.; Rathmann, F.; Reifferscheidt, L.; Soltner, H.; Straatmann, H.; Trinkel, F.; Wolters, J.
2016-08-01
The conventional Wien filter is a device with orthogonal static magnetic and electric fields, often used for velocity separation of charged particles. Here we describe the electromagnetic design calculations for a novel waveguide RF Wien filter that will be employed to solely manipulate the spins of protons or deuterons at frequencies of about 0.1-2 MHz at the COoler SYnchrotron COSY at Jülich. The device will be used in a future experiment that aims at measuring the proton and deuteron electric dipole moments, which are expected to be very small. Their determination, however, would have a huge impact on our understanding of the universe.
The Measurement of Magnetic Fields
ERIC Educational Resources Information Center
Berridge, H. J. J.
1973-01-01
Discusses five experimental methods used by senior high school students to provide an accurate calibration curve of magnet current against the magnetic flux density produced by an electromagnet. Compares the relative merits of the five methods, both as measurements and from an educational viewpoint. (JR)
Measurement of an electron's electric dipole moment using Cs atoms trapped in optical lattices
NASA Astrophysics Data System (ADS)
Chin, Cheng; Leiber, Véronique; Vuletić, Vladan; Kerman, Andrew J.; Chu, Steven
2001-03-01
We propose to measure the electron's permanent electric dipole moment (EDM) using cesium atoms trapped in a sparsely populated, trichromatic, far blue-detuned three-dimensional (3D) optical lattice. In the proposed configuration, the atoms can be strongly localized near the nodes of the light field and isolated from each other, leading to a strong suppression of the detrimental effects of atom-atom and atom-field interactions. Three linearly polarized standing waves with different frequencies create an effectively linearly polarized 3D optical lattice and lead to a strong reduction of the tensor light shift, which remains a potential source of systematic error. Other systematics concerning external field instability and gradients and higher-order polarizabilities are discussed. Furthermore, auxiliary atoms can be loaded into the same lattices as effective ``comagnetometers'' to monitor various systematic effects, including magnetic-field fluctuations and imperfect electric-field reversal. We estimate that a sensitivity 100 times higher than the current upper bound for the electron's EDM of 4×10-27 e cm can be achieved with the proposed technique.
NASA Astrophysics Data System (ADS)
Yakut, H.; Guliyev, E.; Guner, M.; Tabar, E.; Zenginerler, Z.
2012-08-01
A new microscopic method has been developed in the framework of the Quasiparticle-Phonon Nuclear Model (QPNM) in order to investigate spin polarization effects on the magnetic properties such as magnetic moment, intrinsic magnetic moment and effective gs factor of the ground state of odd-mass 157-167Er isotopes. The calculations were performed using both Tamm-Dancoff Approximation (TDA) and Quasiparticle Random-Phase Approximation (QRPA). Reasonably good agreement has been obtained between the QRPA results and the relevant experimental data. Furthermore the variation of the intrinsic magnetic moment gK values with the mass number A exhibits similar behavior for both theoretical and experimental results. From the compression of the calculated intrinsic magnetic moment values with the experimental data the spin-spin interaction parameter has been found as χ=(30/A) MeV for odd-mass 157-167Er isotopes. Our results clarify the possibility of using this new method to describe the magnetic properties of odd-mass deformed nuclei.
Itinerancy-Enhanced Quantum Fluctuation of Magnetic Moments in Iron-Based Superconductors
NASA Astrophysics Data System (ADS)
Tam, Yu-Ting; Yao, Dao-Xin; Ku, Wei
We investigate the influence of itinerant carriers on dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom.Surprisingly against the common lore, instead of enhancing the (π,0) order, itinerant carriers with well nested Fermi surfaces are found to induce a significant amount of spatial and temporal quantum fluctuation that leads to the observed small ordered moment. Interestingly, the underlying mechanism is shown to be intra-pocket nesting-associated long-range coupling rather than the previously believed ferromagnetic double-exchange effect. This challenges the validity of ferromagnetically compensated first-neighbor coupling reported from short-range fitting to the experimental dispersion, which turns out to result instead from the ferro-orbital order that is also found instrumental in stabilizing the magnetic order. *Y.-T. Tam, D.-X. Yao and W. Ku, Phys. Rev. Lett. 115, 117001 (2015) Work supported by US DOE No.DE-AC02-98CH10886 and CHN No. NBRPC-2012CB821400, No. NSFC-11275279.
Suggestion for measuring the weak dipole moment of τ lepton at Z factory
NASA Astrophysics Data System (ADS)
Xu, Qing-Jun; Chang, Chao-Hsi
2015-01-01
Three new observables for Z factory to measure the weak dipole moment of τ lepton (dwτ) are proposed. As those observables are employed at LEP-I, the new observables depend on the real and imaginary parts of dwτ linearly; thus, we calculate the slopes, i.e., the linear coefficients of the dependence, precisely and find that the obtained slopes are much lager than those employed at LEP-I. It means that the signal for the weak dipole moment dwτ may be enhanced quite a lot if one employs the new observables. Being superior to those at LEP-I, we recommend measuring the weak dipole moment dwτ in terms of the new observables if reanalyzing the data of LEP-I or doing the measurement at a possible Z factory in the near future.
The spin and orbital contributions to the total magnetic moments of free Fe, Co, and Ni clusters
Meyer, Jennifer; Tombers, Matthias; Wüllen, Christoph van; Niedner-Schatteburg, Gereon; Peredkov, Sergey; Eberhardt, Wolfgang; Neeb, Matthias; Palutke, Steffen; Martins, Michael; Wurth, Wilfried
2015-09-14
We present size dependent spin and orbital magnetic moments of cobalt (Co{sub n}{sup +}, 8 ≤ n ≤ 22), iron (Fe{sub n}{sup +}, 7 ≤ n ≤ 17), and nickel cluster (Ni{sub n}{sup +}, 7 ≤ n ≤ 17) cations as obtained by X-ray magnetic circular dichroism (XMCD) spectroscopy of isolated clusters in the gas phase. The spin and orbital magnetic moments range between the corresponding atomic and bulk values in all three cases. We compare our findings to previous XMCD data, Stern-Gerlach data, and computational results. We discuss the application of scaling laws to the size dependent evolution of the spin and orbital magnetic moments per atom in the clusters. We find a spin scaling law “per cluster diameter,” ∼n{sup −1/3}, that interpolates between known atomic and bulk values. In remarkable contrast, the orbital moments do likewise only if the atomic asymptote is exempt. A concept of “primary” and “secondary” (induced) orbital moments is invoked for interpretation.
Constraint on the magnetic dipole moment of neutrinos by the tip-RGB luminosity in ω-Centauri
NASA Astrophysics Data System (ADS)
Arceo-Díaz, S.; Schröder, K.-P.; Zuber, K.; Jack, D.
2015-10-01
In this work, we use models constructed with the Eggleton code for stellar evolution, along with the photometric data of the super-rich globular cluster ω-Centauri (Sollima et al., 2004), to put a constraint on the magnetic dipole moment of neutrinos. We begin with a review of the idea proposed by Raffelt and Dearborn (1988), in which, as a consequence of a non-zero magnetic dipole moment, the tip-RGB luminosity of low mass stars gets increased over its standard value. First, we measure the dependence of the He-core mass and bolometric luminosity, at the tip-RGB, on the existing fits to characterize plasmon decay into neutrinos, namely those from Itoh et al. (1992), Haft et al. (1994), and the more recent results from Kantor and Gushakov (2007). Then, stating our definition of the tip-RGB, we revise multiple theoretical aspects: the consequences of non-standard neutrino emission on the internal structure of stellar models, its impact on the calibration of the Reimers mass-loss rate and later evolutionary phases and the influence of initial Helium abundance, metallicity, convection theory and opacities. Finally, we consider the specific case of ω-Cen. Using our tip-RGB models, and the bolometric correction obtained by the PHOENIX code for stellar atmospheres, to estimate the luminosity for canonical and non-standard evolution, also measuring the impact of the reported chemical spread in ω-Cen on our results. We find that the upper limit μν ≤ 2.2 ×10-12μB is already well constrained by observations. This result compares with the one obtained by Viaux et al. (2013), μν ≤ 2.6 ×10-12μB , from photometric study of the globular cluster M5.
ERIC Educational Resources Information Center
Fields, Steve
1987-01-01
Describes a hands-on lesson in magnetism designed to be used with upper elementary grade students. Emphasizes structured experiences which involve the student in measuring, data collecting, graphing, and extrapolating information. (TW)
Measuring Earth's Magnetic Field Simply.
ERIC Educational Resources Information Center
Stewart, Gay B.
2000-01-01
Describes a method for measuring the earth's magnetic field using an empty toilet paper tube, copper wire, clear tape, a battery, a linear variable resistor, a small compass, cardboard, a protractor, and an ammeter. (WRM)
Bound on the tau neutrino magnetic moment from the TRISTAN experiments
NASA Astrophysics Data System (ADS)
Tanimoto, N.; Nakano, I.; Sakuda, M.
2000-04-01
We set limits on the magnetic moment and charge radius of the tau neutrino by examining an extra contribution to the electroweak process e+e--->ν
Magnetic moment and plasma environment of HD 209458b as determined from Lyα observations
NASA Astrophysics Data System (ADS)
Kislyakova, Kristina G.; Holmström, Mats; Lammer, Helmut; Odert, Petra; Khodachenko, Maxim L.
2014-11-01
Transit observations of HD 209458b in the stellar Lyman-α(Lyα) line revealed strong absorption in both blue and red wings of the line interpreted as hydrogen atoms escaping from the planet’s exosphere at high velocities. The following sources for the absorption were suggested: acceleration by the stellar radiation pressure, natural spectral line broadening, or charge exchange with the stellar wind. We reproduced the observation by means of modeling that includes all aforementioned processes. Our results support a stellar wind with a velocity of ≈400 kilometers per second at the time of the observation and a planetary magnetic moment of ≈1.6 × 1026 amperes per square meter.
Four-flavour leading-order hadronic contribution to the muon anomalous magnetic moment
Burger, Florian; Feng, Xu; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; Renner, Dru B.
2014-02-24
We present a four-flavour lattice calculation of the leading-order hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, aμhvp, arising from quark-connected Feynman graphs. It is based on ensembles featuring Nf=2+1+1 dynamical twisted mass fermions generated by the European Twisted Mass Collaboration (ETMC). Several light quark masses are used in order to yield a controlled extrapolation to the physical pion mass. We employ three lattice spacings to examine lattice artefacts and several different volumes to check for finite-size effects. Including the complete first two generations of quarks allows for a direct comparison with phenomenological determinations of amore » μhvp. The final result involving an estimate of the systematic uncertainty aμhvp=6.74 (21)(18) 10-8 shows a good overall agreement with these computations.« less
Concentric transmon qubit featuring fast tunability and an anisotropic magnetic dipole moment
NASA Astrophysics Data System (ADS)
Braumüller, Jochen; Sandberg, Martin; Vissers, Michael R.; Schneider, Andre; Schlör, Steffen; Grünhaupt, Lukas; Rotzinger, Hannes; Marthaler, Michael; Lukashenko, Alexander; Dieter, Amadeus; Ustinov, Alexey V.; Weides, Martin; Pappas, David P.
2016-01-01
We present a planar qubit design based on a superconducting circuit that we call concentric transmon. While employing a straightforward fabrication process using Al evaporation and lift-off lithography, we observe qubit lifetimes and coherence times in the order of 10 μ s . We systematically characterize loss channels such as incoherent dielectric loss, Purcell decay and radiative losses. The implementation of a gradiometric SQUID loop allows for a fast tuning of the qubit transition frequency and therefore for full tomographic control of the quantum circuit. Due to the large loop size, the presented qubit architecture features a strongly increased magnetic dipole moment as compared to conventional transmon designs. This renders the concentric transmon a promising candidate to establish a site-selective passive direct Z ̂ coupling between neighboring qubits, being a pending quest in the field of quantum simulation.
Four-flavour leading-order hadronic contribution to the muon anomalous magnetic moment
Burger, Florian; Feng, Xu; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; Renner, Dru B.
2014-02-24
We present a four-flavour lattice calculation of the leading-order hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, aμ^{hvp}, arising from quark-connected Feynman graphs. It is based on ensembles featuring N_{f}=2+1+1 dynamical twisted mass fermions generated by the European Twisted Mass Collaboration (ETMC). Several light quark masses are used in order to yield a controlled extrapolation to the physical pion mass. We employ three lattice spacings to examine lattice artefacts and several different volumes to check for finite-size effects. Including the complete first two generations of quarks allows for a direct comparison with phenomenological determinations of a μ^{hvp}. The final result involving an estimate of the systematic uncertainty a_{μ}^{hvp}=6.74 (21)(18) 10^{-8} shows a good overall agreement with these computations.
Miller, D.; Milton, K.A.; Siegemund-Broka, S. )
1992-07-15
This is the first in a series of papers dealing with four-dimensional quantum electrodynamics on a finite-element lattice. We begin by studying the canonical structure of the theory without interactions. This tells us how to construct momentum expansions for the field operators. Next we examine the interaction term in the Dirac equation. We construct the transfer matrix explicitly in the temporal gauge, and show that it is unitary. Therefore, fermion canonical anticommutation relations hold at each lattice site. Finally, we expand the interaction term to second order in the temporal-lattice spacing and deduce the magnetic moment of the electron in a background field, consistent with the continuum value of {ital g}=2.
Dark matter, LFV and neutrino magnetic moment in the radiative seesaw model with fermion triplet
NASA Astrophysics Data System (ADS)
Chao, Wei
2015-01-01
In this paper we work in the framework of a radiative seesaw model with triplet fermion Σ. Due to the Z2 discrete flavor symmetry, the lightest neutral component of Σ is stable and thus can be a dark matter candidate. Its mass can be solely determined by the dark matter relic abundance, which is bout 2.594 TeV. It can still constitute 30% of the dark matter when considering constraints from dark matter indirect detection experiments. The model also predict a dark matter-nucleus scattering cross-section that would be accessible with future dark matter direct detection searches. We further investigate constraints on the parameter space of the model from the lepton-flavor-violating processes and neutrino transition magnetic moments, induced by the Yukawa interaction of the Σ with the left-handed lepton doublets.
Phonon coupling effects in magnetic moments of magic and semimagic nuclei
NASA Astrophysics Data System (ADS)
Saperstein, E. E.; Achakovskiy, O. I.; Kamerdzhiev, S. P.; Krewald, S.; Speth, J.; Tolokonnikov, S. V.
2014-08-01
Phonon coupling (PC) corrections to magnetic moments of odd neighbors of magic and semimagic nuclei are analyzed within the self-consistent Theory of Finite Fermi Systems (TFFS) based on the Energy Density Functional by S. A. Fayans et al. The perturbation theory in g {/L 2} is used where g L is the phonon-particle coupling vertex. A model is developed with separating non-regular PC contributions, the rest is supposed to be regular and included into the standard TFFS parameters. An ansatz is proposed to take into account the so-called tadpole term which ensures the total angular momentum conservation with g {/L 2} accuracy. An approximate method is suggested to take into account higher-order terms in g {/L 2}. Calculations are carried out for four odd-proton chains, the odd Tl, Bi, In, and Sb ones. Different PC corrections strongly cancel each other. In the result, the total PC correction to the magnetic moment in magic nuclei is, as a rule, negligible. In non-magic nuclei considered it is noticeable and, with only one exception, negative. On average it is of the order of -(0.1-0.5) µ N and improves the agreement of the theory with the data. Simultaneously we calculated the gyromagnetic ratios g {/L ph} of all low-lying phonons in 208Pb. For the 3{1/-} state it is rather close to the Bohr-Mottelson model prediction whereas for other L phonons, two 5- and six positive parity states, the difference from the Bohr-Mottelson values is significant.
NASA Astrophysics Data System (ADS)
Sun, X.; Wang, B.; Pratt, A.; Yamauchi, Y.
2014-07-01
The geometric, electronic, and magnetic structures of a manganese phthalocyanine (MnPc) molecule on an antiferromagnetic IrMn(100) surface are studied by density functional theory calculations. Two kinds of orientation of the adsorbed MnPc molecule are predicted to coexist due to molecular self-assembly on the surface—a top-site geometry with the Mn-N bonds aligned along the ⟨100⟩ direction, and a hollow-site orientation in which the Mn-N bonds are parallel to the ⟨110⟩ direction. The MnPc molecule is antiferromagnetically coupled to the substrate at the top site with a slight reduction in the magnetic moment of the Mn atom of the MnPc molecule (Mnmol). In contrast, the magnetic moment of the Mnmol is enhanced to 4.28 μB at the hollow site, a value larger than that in the free MnPc molecule (3.51 μB). Molecular distortion induced by adsorption is revealed to be responsible for the enhancement of the magnetic moment. Furthermore, the spin polarization of the Mnmol atom at around the Fermi level is found to change from negative to positive through an elongation of the Mn-N bonds of the MnPc. We propose that a reversible switch of the low/high magnetic moment and negative/positive spin polarization might be realized through some mechanical engineering methods.
NASA Astrophysics Data System (ADS)
Boda, Aalu; Kumar, D. Sanjeev; Sankar, I. V.; Chatterjee, Ashok
2016-11-01
The problem of a parabolically confined two-dimensional semiconductor GaAs quantum dot with two interacting electrons in the presence of an external magnetic field and the spin-Zeeman interaction is studied using a method of numerical diagonalization. The energy spectrum is calculated as a function of the magnetic field. The magnetic moment (M) and the magnetic susceptibility (χ) show zero temperature diamagnetic peaks due to the exchange induced singlet-triplet transitions. The position and the number of these peaks depend both on the confinement strength of the quantum dot and the strength of the electron-electron interaction (β) .
NASA Astrophysics Data System (ADS)
Chakraborty, Bipasha; Davies, C. T. H.; Koponen, J.; Lepage, G. P.; Peardon, M. J.; Ryan, S. M.
2016-04-01
The quark-line disconnected diagram is a potentially important ingredient in lattice QCD calculations of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon. It is also a notoriously difficult one to evaluate. Here, for the first time, we give an estimate of this contribution based on lattice QCD results that have a statistically significant signal, albeit at one value of the lattice spacing and an unphysically heavy value of the u /d quark mass. We use HPQCD's method of determining the anomalous magnetic moment by reconstructing the Adler function from time moments of the current-current correlator at zero spatial momentum. Our results lead to a total (including u , d and s quarks) quark-line disconnected contribution to aμ of -0.15 % of the u /d hadronic vacuum polarization contribution with an uncertainty which is 1% of that contribution.
Calculation of Moments from Measurements by the Los Alamos Magnetospheric Plasma Analyzer
M. F. Thomsen; E. Noveroske; J. E. Borovsky; D. J. McComas
1999-05-01
The various steps involved in computing the moments (density, velocity, and temperature) of the ion and electron distributions measured with the Los Alamos Magnetospheric Plasma Analyzer (MPA) are described. The assumptions, constants, and algorithms contained in the FORTRAN code are presented, as well as the output parameters produced by the code.
Tsaopoulos, Dimitrios E; Baltzopoulos, Vasilios; Maganaris, Constantinos N
2006-08-01
Detailed understanding of the knee joint loading requires the calculation of muscle and joint forces in different conditions. In these applications the patellar tendon moment arm length is essential for the accurate estimation of the tibiofemoral joint loading. In this article, different methods that have been used to determine the patellar tendon moment arm length under in vivo and in vitro conditions are reviewed. The limitations and advantages associated with each of the methods are evaluated together with their applications in the different loading conditions that the musculoskeletal system is subjected to. The three main measurement methods that this review considers are the geometric method, the tendon excursion method and the direct load method. A comparison of relevant quantitative results is presented to asses the impact of the errors of each method on the quantification of the patellar tendon moment arm and the implications for joint loading assessment in clinical applications.
Tsunami magnetic signals in the Northwestern Pacific seafloor magnetic measurements
NASA Astrophysics Data System (ADS)
Schnepf, N. R.; An, C.; Nair, M. C.; Maus, S.
2013-12-01
In the past two decades, underwater cables and seafloor magnetometers have observed motional inductance from ocean tsunamis. This study aimed to characterize the electromagnetic signatures of tsunamis from seafloor stations to assist in the long-term goal of real-time tsunami detection and warning systems. Four ocean seafloor stations (T13, T14, T15, T18) in the Northeastern Philippine Sea collected vector measurements of the electric and magnetic fields every minute during the period of 10/05/2005 to 11/30/2007 (Baba et al., 2010 PEPI). During this time, four major tsunamis occurred as a result of moment magnitude 8.0-8.1 earthquakes. These tsunamis include the 05/03/2006 Tonga event, the 01/13/2007 Kuril Islands event, the 04/01/2007 Solomon Islands event, and the 08/15/2007 Peru event. The Cornell Multi-grid Coupled Tsunami model (COMCOT) was used to predict the arrival time of the tsunamis at each of the seafloor stations. The stations' raw magnetic field signals underwent a high pass filter to then be examined for signals of the tsunami arrival. The high pass filtering showed clear tsunami signals for the Tonga event, but a clear signal was not seen for the other events. This may be due to signals from near Earth space with periods similar to tsunamis. To remove extraneous atmospheric magnetic signals, a cross-wavelet analysis was conducted using the horizontal field components from three INTERMAGNET land stations and the vertical component from the seafloor stations. The cross-wavelet analysis showed that for three of the six stations (two of the four tsunami events) the peak in wavelet amplitude matched the arrival of the tsunami. We discuss implications of our finding in magnetic monitoring of tsunamis.
Preparing the measurement of anapole moment in a chain of francium isotopes
NASA Astrophysics Data System (ADS)
Sheng, Dong
This thesis presents the current status of the experimental efforts towards the measurement of the anapole moment in francium. The anapole moment is a parity violating, time-reversal conserving nuclear moment that arises from the weak interaction among nucleons. It is nuclear spin dependent and sensitive to the configuration of nuclear structure. Our experimental scheme is to perform a direct measurement of the anapole moment, by driving a parity forbidden E1 transition between ground hyperfine states in a series of francium isotopes inside a blue detuned dipole trap at the electric anti-node of a microwave cavity. We explore the tests using rubidium isotopes. The francium experiment will be moved to the ISAC radioactive beam facility of TRIUMF, Canada. During the preparation of the apparatus, we test the coherent control of the ground states via microwave and Raman beams, characterize the performance of a blue detuned dipole trap and study the atomic dynamics inside it using both classical and quantum methods. We also measure the lifetime of excited 5d states in Rb, with less than 1% uncertainty, to test and help to improve the current atomic structure theories.
Packwood, D. M.; Reaves, K. T.; Federici, F. L.; Katzgraber, H. G.; Teizer, W.
2013-01-01
An open problem in applied mathematics is to predict interesting molecules that are realistic targets for chemical synthesis. In this paper, we use a spin Hamiltonian-type model to predict molecular magnets (MMs) with magnetic moments that are intrinsically robust under random shape deformations to the molecule. Using the concept of convergence in probability, we show that for MMs in which all spin centres lie in-plane and all spin centre interactions are ferromagnetic, the total spin of the molecule is a ‘weak topological invariant’ when the number of spin centres is sufficiently large. By weak topological invariant, we mean that the total spin of the molecule depends only upon the arrangement of spin centres in the molecule, and is unlikely to change under shape deformations to the molecule. Our calculations show that only between 20 and 50 spin centres are necessary for the total spin of these MMs to be a weak topological invariant. The robustness effect is particularly enhanced for two-dimensional ferromagnetic MMs that possess a small number of spin rings in the structure. PMID:24353469
Buehler, Marc; Tartaglia, Michael; Tompkins, John; Orozco, Charles
2014-07-01
The Mu2e experiment at Fermilab is designed to explore charged lepton flavor violation by searching for muon-to-electron conversion. The magnetic field generated by a system of solenoids is crucial for Mu2e and requires accurate characterization to detect any flaws and to produce a detailed field map. Stringent physics goals are driving magnetic field specifications for the Mu2e solenoids. A field mapper is being designed, which will produce detailed magnetic field maps. The uniform field region of the spectrometer volume requires the highest level of precision (1 Gauss per 1 Tesla). During commissioning, multiple magnetic field maps will be generated to verify proper alignment of all magnet coils, and to create the final magnetic field map. In order to design and build a precise field mapping system consisting of Hall and NRM probes, tolerances and precision for such a system need to be evaluated. In this paper we present a design for the Mu2e field mapping hardware, and discuss results from OPERA-3D simulations to specify parameters for Hall and NMR probes. We also present a fitting procedure for the analytical treatment of our expected magnetic measurements.
SQUIDs as Detectors in a New Experiment to Measure the Neutron Electric Dipole Moment
Espy, M.A.; Cooper, M.; Lamoreaux, S.; Kraus, R.H., Jr.; Matlachov, A.; Ruminer, P.
1998-09-13
A new experiment has been proposed at Los Alamos National Laboratory to measure the neutron electric dipole moment (EDM) to 4x10{sup {minus}28} ecm, a factor of 250 times better than the current experimental limit. Such a measure of the neutron EDM would challenge the theories of supersymmetry and time reversal violation as the origin of the observed cosmological asymmetry in the ratio of baryons to antibaryons. One possible design for this new experiment includes the use of LTC SQUIDs coupled to large ({approximately}100 cm{sup 2}) pick-up coils to measure the precession frequency of the spin-polarized {sup 3}He atoms that act as polarizer, spin analyzer, detector, and magnetometer for the ultra-cold neutrons used in the experiment. The method of directly measuring the {sup 3}He precession signal eliminates the need for very uniform magnetic fields (a major source of systematic error in these types of experiments). It is estimated that a flux of {approximately}2x10{sup {minus}16} Tm{sup 2} (0.1 F{sub 0}) will be coupled into the pick-up coils. To achieve the required signal-to-noise ratio one must have a flux resolution of d F{sub SQ}=2x10{sup {minus}6} F{sub 0}/{radical}Hz at 10 Hz. While this is close to the sensitivity available in commercial devices, the effects of coupling to such a large pick-up coil and flux noise from other sources in the experiment still need to be understood. To determine the feasibility of using SQUIDs in such an application we designed and built a superconducting test cell, which simulates major features of the proposed EDM experiment, and we developed a two-SQUID readout system that will reduce SQUID noise in the experiment. We present an overview of the EDM experiment with SQUIDs, estimations of required SQUID parameters and experimental considerations. We also present the measured performance of a single magnetometer in the test cell as well as the performance of the two SQUID readout technique
SQUIDs as detectors in a new experiment to measure the neutron electric dipole moment
Espy, M.A.; Cooper, M.; Lamoreaux, S.; Kraus, R.H. Jr.; Matlachov, A.; Ruminer, P.
1998-12-31
A new experiment has been proposed at Los Alamos National Laboratory to measure the neutron electric dipole moment (EDM) to 4{times}10{sup {minus}28} ecm, a factor of 250 times better than the current experimental limit. Such a measure of the neutron EDM would challenge the theories of supersymmetry and time reversal violation as the origin of the observed cosmological asymmetry in the ratio of baryons to antibaryons. One possible design for this new experiment includes the use of LTC SQUIDs coupled to large ({approximately}100 cm{sup 2}) pick-up coils to measure the precision frequency of the spin-polarized {sup 3}He atoms that act as polarizer, spin analyzer, detector, and magnetometer for the ultra-cold neutrons used in the experiment. The method of directly measuring the {sup 3}He precession signal eliminates the need for very uniform magnetic fields (a major source of systematic error in these types of experiments). It is estimated that a flux of {approximately}2{times}10{sup {minus}16} Tm{sup 2} (0.1 {Phi}{sub 0}) will be coupled into the pick-up coils. To achieve the required signal-to-noise ratio one must have a flux resolution of d{Phi}{sub SQ} = 2{times}10{sup {minus}6}{Phi}{sub 0}/{radical}Hz at 10 Hz. While this is close to the sensitivity available in commercial devices, the effects of coupling to such a large pick-up coil and flux noise from other sources in the experiment still need to be understood. To determine the feasibility of using SQUIDs in such an application the authors designed and built a superconducting test cell, which simulates major features of the proposed EDM experiment, and they developed a two-SQUID readout system that will reduce SQUID noise in the experiment. They present an overview of the EDM experiment with SQUIDs, estimations of required SQUID parameters and experimental considerations. The authors also present the measured performance of a single magnetometer in the test cell as well as the performance of the two SQUID
NASA Astrophysics Data System (ADS)
Mohanta, S. K.; Mishra, S. N.; Srivastava, S. K.
2014-04-01
We present first principles calculations of electronic structure and magnetic properties of dilute transition metal (3d, 4d and 5d) impurities in a Gd host. The calculations have been performed within the density functional theory using the full potential linearized augmented plane wave technique and the GGA+U method. The spin and orbital contributions to the magnetic moment and the hyperfine fields have been computed. We find large magnetic moments for 3d (Ti-Co), 4d (Nb-Ru) and 5d (Ta-Os) impurities with magnitudes significantly different from the values estimated from earlier mean field calculation [J. Magn. Magn. Mater. 320 (2008) e446-e449]. The exchange interaction between the impurity and host Gd moments is found to be positive for early 3d elements (Sc-V) while in all other cases an anti-ferromagnetic coupling is observed. The trends for the magnetic moment and hyperfine field of d-impurities in Gd show qualitative difference with respect to their behavior in Fe, Co and Ni. The calculated total hyperfine field, in most cases, shows excellent agreement with the experimental results. A detailed analysis of the Fermi contact hyperfine field has been made, revealing striking differences for impurities having less or more than half filled d-shell. The impurity induced perturbations in host moments and the change in the global magnetization of the unit cell have also been computed. The variation within each of the d-series is found to correlate with the d-d hybridization strength between the impurity and host atoms.
W.T. Chiang; Marc Vanderhaeghen; S.N. Yang; D. Drechsel
2004-09-01
Radiative pion photoproduction in the {Delta}(1232) resonance region is studied with the aim to access the {Delta}{sup +}(1232) magnetic dipole moment. We present a unitary model of the {gamma}p {yields} {gamma}{pi}N ({pi}N) = ({pi}{sup 0}p, {pi}{sup +}n) reactions, where the {pi}N rescattering is included in an on-shell approximation. In this model, the low energy theorem which couples the {gamma}p {yields} {gamma}{pi}N process in the limit of a soft final photon to the {gamma}p {yields} {pi}N process is exactly satisfied. We study the sensitivity of the {gamma}p {yields} {gamma}{pi}{sup 0}p process at higher values of the final photon energy to the {Delta}{sup +}(1232) magnetic dipole moment. We compare our results with existing data and give predictions for forthcoming measurements of angular and energy distributions. It is found that the photon asymmetry and a helicity cross section are particularly sensitive to the {Delta}{sup +} magnetic dipole moment.
RESONANCE METHOD OF ELECTRIC-DIPOLE-MOMENT MEASUREMENTS IN STORAGE RINGS.
ORLOV, Y.F.; MORSE, W.M.; SEMERTZIDIS, Y.K.
2006-05-10
A ''resonance method'' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.
Resonance Method of Electric-Dipole-Moment Measurements in Storage Rings
Orlov, Yuri F.; Morse, William M.; Semertzidis, Yannis K.
2006-06-02
A 'resonance method' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles' velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.
Continuous measurement of atom-number moments of a Bose-Einstein condensate by photodetection
Prataviera, G.A.; Oliveira, M.C. de
2004-07-01
We propose a measurement scheme that allows determination of even moments of a Bose-Einstein condensate (BEC) atom number, in a ring cavity, by continuous photodetection of an off-resonant quantized optical field. A fast cavity photocounting process limits the heating of atomic samples with a relatively small number of atoms, being convenient for BECs on microchip scale applications. The measurement back-action introduces a counting-conditioned phase damping, suppressing the condensate typical collapse and revival dynamics.
NASA Astrophysics Data System (ADS)
Adachi, T.; Cummer, S. A.; Li, J.; Lehtinen, N. G.; Takahashi, Y.; Hsu, R.; Su, H.; Chen, A. B.; Mende, S. B.; Frey, H. U.
2009-12-01
From July 2004 to June 2007, the FORMOSAT-2/ISUAL spectrophotometer and Duke magnetometer observed clear optical and radio signatures of 12 sprite-producing lightning events. In 10 of these, 777.4-nm luminosity normalized to a distance of 3000 km was almost linearly correlated with current moment with a scaling factor of ~0.82 MR/kAkm. This finding provides a possible new way to remotely measure lightning current moment, which is critical for understanding the production of sprites, through satellite-based optical measurements. Using the scaling factor obtained, we further analyzed ISUAL-observed 85 lightning events producing TLEs. Out of 85 cases, 24 events produced pure haloes, 22 events produced pure sprites, and 39 events produced the combinations of a halo and sprites. The average timescale and charge moment of lightning were <1 ms and ~300 C-km in pure halo events, ~1 ms and ~600 C-km in halo-sprite events, and >>1 ms and ~600 C-km in pure sprite events, respectively. The charge moment values estimated were somewhat smaller than the previous results of Adachi et al. [2008], but the overall tendency was clearly consistent. In order to further discuss their generation processes, we will compare the observational results with theoretical calculations using self-consistent quasi-electrostatic model.
NASA Astrophysics Data System (ADS)
Dyukarev, Yu M.
2016-04-01
The ranks of the limit Weyl intervals are known to serve as the geometric measure of degeneracy of the solution set to a Stieltjes matrix moment problem. This paper puts forward the first operator measure of degeneracy for the solution set to a Stieltjes matrix moment problem in terms of the deficiency vectors of a pair of associated positive symmetric operators. A relationship between the geometric and operator measures of degeneracy for a Stieltjes matrix moment problem is established, from which some corollaries about the Stieltjes matrix moment problem are obtained.Bibliography 19 titles.
Ito, Keita; Sanai, Tatsunori; Yasutomi, Yoko; Toko, Kaoru; Honda, Syuta; Suemasu, Takashi; Zhu, Siyuan; Kimura, Akio; Ueda, Shigenori; Takeda, Yukiharu; Saitoh, Yuji; Imai, Yoji
2013-12-02
We evaluated electronic structures and magnetic moments in Co{sub 3}FeN epitaxial films on SrTiO{sub 3}(001). The experimentally obtained hard x-ray photoemission spectra of the Co{sub 3}FeN film have a good agreement with those calculated. Site averaged spin magnetic moments deduced by x-ray magnetic circular dichroism were 1.52 μ{sub B} per Co atom and 2.08 μ{sub B} per Fe atom at 100 K. They are close to those of Co{sub 4}N and Fe{sub 4}N, respectively, implying that the Co and Fe atoms randomly occupy the corner and face-centered sites in the Co{sub 3}FeN unit cell.
Enhancement of magnetic moment in ZnxFe3-xO4 thin films with dilute Zn substitution
NASA Astrophysics Data System (ADS)
Yuan, Honglei; Liu, Er; Yin, Yuli; Zhang, Wen; Wong, P. K. Johnny; Zheng, Jian-Guo; Huang, Zhaocong; Ou, Huiling; Zhai, Ya; Xu, Qingyu; Du, Jun; Zhai, Hongru
2016-06-01
Highly (111)-textured ZnxFe3-xO4 thin films were grown by pulsed laser deposition on silicon substrates. The spin and orbital magnetic moments of the ZnxFe3-xO4 thin films have been obtained by X-ray magnetic circular dichroism (XMCD) and sum rule analysis. The total magnetic moments thus extracted are in good agreement with the values obtained by vibrating sample magnetometer. Both the unquenched orbital moment and the ratio of orbital-to-spin moment first increase significantly with increasing Zn substitution at a low concentration range ( 0 ≤x ≤0.1 ), and then decrease at a higher concentration (x = 0.3). The underlying site-specific doping mechanisms involved here have been elucidated by detailed analysis of the XMCD of ZnxFe3-xO4 films. Our work demonstrates a practical means to manipulate the spin-orbit coupling in the ZnxFe3-xO4 thin films via Zn impurity doping.
Measurement of whole-body human centers of gravity and moments of inertia.
Albery, C B; Schultz, R B; Bjorn, V S
1998-06-01
With the inclusion of women in combat aircraft, the question of safe ejection seat operation has been raised. The potential expanded population of combat pilots would include both smaller and larger ejection seat occupants, which could significantly affect seat performance. The method developed to measure human whole-body CG and MOI used a scale, a knife edge balance, and an inverted torsional pendulum. Subjects' moments of inertia were measured along six different axes. The inertia tensor was calculated from these values, and principal moments of inertia were then derived. Thirty-eight antropometric measurements were also taken for each subject to provide a means for direct correlation of inertial properties to body dimensions and for modeling purposes. Data collected in this study has been used to validate whole-body mass properties predictions. In addition, data will be used to improve Air Force and Navy ejection seat trajectory models for the expanded population. PMID:11542768
Yukawa coupling and anomalous magnetic moment of the muon: An update for the LHC era
Crivellin, Andreas; Girrbach, Jennifer; Nierste, Ulrich
2011-03-01
We study the interplay between a soft muon Yukawa coupling generated radiatively with the trilinear A-terms of the minimal supersymmetric standard model (MSSM) and the anomalous magnetic moment of the muon. In the absence of a tree-level muon Yukawa coupling the lightest smuon mass is predicted to be in the range between 600 GeV and 2200 GeV at 2{sigma}, if the bino mass M{sub 1} is below 1 TeV. Therefore, a detection of a smuon (in conjunction with a sub-TeV bino) at the LHC would directly imply a nonzero muon Yukawa coupling in the MSSM superpotential. Inclusion of slepton flavor mixing could in principle lower the mass of one smuonlike slepton below 600 GeV. However, the experimental bounds on radiative lepton decays instead strengthen the lower mass bound, with larger effects for smaller M{sub 1}, We also extend the analysis to the electron case and find that a light selectron close to the current experimental search limit may prove the MSSM electron Yukawa coupling to be nonzero.
Macroscopic kinematics of the Hall electric field under influence of carrier magnetic moments
NASA Astrophysics Data System (ADS)
Sakai, Masamichi
2016-06-01
The relativistic effect on electromagnetic forces yields two types of forces which depend on the velocity of the relevant particles: (i) the usual Lorentz force exerted on a moving charged particle and (ii) the apparent Lorentz force exerted on a moving magnetic moment. In sharp contrast with type (i), the type (ii) force originates due to the transverse field induced by the Hall effect (HE). This study incorporates both forces into a Drude-type equation with a fully spin-polarized condition to investigate the effects of self-consistency of the source and the resultant fields on the HE. We also examine the self-consistency of the carrier kinematics and electromagnetic dynamics by simultaneously considering the Drude type equation and Maxwell equations at low frequencies. Thus, our approach can predict both the dc and ac characteristics of the HE, demonstrating that the dc current condition solely yields the ordinary HE, while the ac current condition yields generation of both fundamental and second harmonic modes of the HE field. When the magnetostatic field is absent, the simultaneous presence of dc and ac longitudinal currents generates the ac HE that has both fundamental frequency and second harmonic.
Paramagnons in the PrNi system with an induced magnetic moment
Tiden, N. N. Clement'ev, E. S.; Alekseev, P. A.; Gvasaliya, S. N.; Nefedova, E. V.; Lazukov, V. N.; Sadikov, I. P.
2006-12-15
The recent studies of the PrNi system have shown that, at a temperature slightly higher than the ferromagnetic ordering temperature (T{sub C} {approx} 21 K), softening of some part of magnetic excitations occurs near the {gamma} point of the Brillouin zone. The magnetic modes observed have been qualitatively described by a model taking into account the crystal field and the exchange interaction within the mean-field random-phase approximation. To refine the model parameters and obtain a complete set of excitation modes, inelastic neutron scattering measurements on PrNi single crystals and polycrystals have been performed at T = 23 K. An acoustic branch related to the level with high excitation energy has been observed for the first time. The character of its dispersion suggests that the low-energy acoustic mode is responsible for the magnetic phase transition.
Buchanan, Thomas S.; Lloyd, David G.; Manal, Kurt; Besier, Thor F.
2005-01-01
This paper provides an overview of forward dynamic neuromusculoskeletal modeling. The aim of such models is to estimate or predict muscle forces, joint moments, and/or joint kinematics from neural signals. This is a four-step process. In the first step, muscle activation dynamics govern the transformation from the neural signal to a measure of muscle activation—a time varying parameter between 0 and 1. In the second step, muscle contraction dynamics characterize how muscle activations are transformed into muscle forces. The third step requires a model of the musculoskeletal geometry to transform muscle forces to joint moments. Finally, the equations of motion allow joint moments to be transformed into joint movements. Each step involves complex nonlinear relationships. The focus of this paper is on the details involved in the first two steps, since these are the most challenging to the biomechanician. The global process is then explained through applications to the study of predicting isometric elbow moments and dynamic knee kinetics. PMID:16467928
Individual Mammalian Cell Magnetic Measurements with a Superconducting Quantum Interference Device
NASA Astrophysics Data System (ADS)
Palmstrom, Johanna C.; Brewer, Kimberly; Tee, Sui Seng; Theis, Eric; Rutt, Brian; Moler, Kathryn A.
2015-03-01
Magnetism can be introduced into otherwise nonmagnetic cells by the uptake of superparamagnetic iron oxide (SPIO) nanoparticles. SPIO nanoparticles are used in numerous biomedical applications including cellular therapies and targeted drug delivery. Currently there are few tools capable of characterizing individual magnetic nanoparticles and the magnetic properties of individual mammalian cells loaded with SPIO. Our scanning superconducting quantum interference devices (SQUIDs) are good candidates for these measurements due to their high sensitivity to magnetic dipole moments (approx. 200 μb/ √Hz) In this study, we use a scanning SQUID to image the magnetic flux from SPIO loaded H1299 lung cancer cells. We find that the magnetic moment spatially varies inside the cell with each cell having a unique distribution of moments. We also correlate these magnetic images with optical and scanning electron microscope images. These results show that the SQUID is a useful tool for imaging biological magnetism. The visualization of single cell magnetism and the quantification of magnetic dipole moments in magnetically labeled cells can be used to optimize conventional biological magnetic imaging techniques, such as MRI.
Sun, X.; Wang, B.; Pratt, A.; Yamauchi, Y.
2014-07-21
The geometric, electronic, and magnetic structures of a manganese phthalocyanine (MnPc) molecule on an antiferromagnetic IrMn(100) surface are studied by density functional theory calculations. Two kinds of orientation of the adsorbed MnPc molecule are predicted to coexist due to molecular self-assembly on the surface—a top-site geometry with the Mn–N bonds aligned along the 〈100〉 direction, and a hollow-site orientation in which the Mn–N bonds are parallel to the 〈110〉 direction. The MnPc molecule is antiferromagnetically coupled to the substrate at the top site with a slight reduction in the magnetic moment of the Mn atom of the MnPc molecule (Mn{sub mol}). In contrast, the magnetic moment of the Mn{sub mol} is enhanced to 4.28 μB at the hollow site, a value larger than that in the free MnPc molecule (3.51 μB). Molecular distortion induced by adsorption is revealed to be responsible for the enhancement of the magnetic moment. Furthermore, the spin polarization of the Mn{sub mol} atom at around the Fermi level is found to change from negative to positive through an elongation of the Mn–N bonds of the MnPc. We propose that a reversible switch of the low/high magnetic moment and negative/positive spin polarization might be realized through some mechanical engineering methods.
Measurement of the Moments of the Hadronic Invariant Mass Distribution in Semileptonic Beta Decays
Acosta, D.; The CDF Collaboration TITLE=Measuremen
2005-03-13
Using 180 pb{sup -1} of data collected with the CDF II detector at the Tevatron, we measure the first two moments of the hadronic invariant mass-squared distribution in charmed semileptonic B decays. From these we determine the non-perturbative Heavy Quark Effective Theory parameters {Lambda} and {lambda}{sub 1} used to relate the B meson semileptonic branching ratio to the CKM matrix element |V{sub cb}|.
Meinert, M.; Schmalhorst, J; Klewe, C.; Reiss, G.; Arenholz, E.; Bohnert, T.; Nielsch, K.
2011-08-08
Epitaxial thin films of the half-metallic X{sub a}-compound Mn{sub 2}CoGa (Hg{sub 2}CuTi prototype) were prepared by dc magnetron co-sputtering with different heat treatments on MgO (001) substrates. High-quality lms with a bulk magnetization of 1.95(5) {mu}{sub }B per unit cell were obtained. The average Mn magnetic moment and the Co moment are parallel, in agreement with theory. The x-ray magnetic circular dichroism spectra agree with calculations based on density functional theory and reveal the antiparallel alignment of the two inequivalent Mn moments. X-ray magnetic linear dichroism allows to distinguish between itinerant and localized Mn moments. It is shown that one of the two Mn moments has localized character, whereas the other Mn moment and the Co moment are itinerant.
Kohn, Gabriel; Hicho, George; Swartzendruber, Lydon
1997-01-01
A steel hardness measurement system and method of using same are provided for measuring at least one mechanical or magnetic characteristic of a ferromagnetic sample as a function of at least one magnetic characteristic of the sample. A magnetic field generator subjects the sample to a variable external magnetic field. The magnetic field intensity of the magnetic field generated by the magnetic field generating means is measured and a signal sensor is provided for measuring Barkhausen signals from the sample when the sample is subjected to the external magnetic field. A signal processing unit calculates a jump sum rate first moment as a function of the Barkhausen signals measured by the signal sensor and the magnetic field intensity, and for determining the at least one mechanical or magnetic characteristic as a function of the jump sum rate first moment.
Kohn, G.; Hicho, G.; Swartzendruber, L.
1997-04-08
A steel hardness measurement system and method of using same are provided for measuring at least one mechanical or magnetic characteristic of a ferromagnetic sample as a function of at least one magnetic characteristic of the sample. A magnetic field generator subjects the sample to a variable external magnetic field. The magnetic field intensity of the magnetic field generated by the magnetic field generating means is measured and a signal sensor is provided for measuring Barkhausen signals from the sample when the sample is subjected to the external magnetic field. A signal processing unit calculates a jump sum rate first moment as a function of the Barkhausen signals measured by the signal sensor and the magnetic field intensity, and for determining the at least one mechanical or magnetic characteristic as a function of the jump sum rate first moment. 7 figs.
Preparation of the anapole moment measurement in a chain of isotopes
NASA Astrophysics Data System (ADS)
Sheng, Dong; Hood, Jonathan; Orozco, Luis
2010-02-01
We present the current status of the experimental effort towards the measurement of the anapole moment in different isotopes of francium. The anapole is a parity violating, time reversal conserving nuclear moment that arises from the weak interaction among nucleons, and should be sensitive to the changes in the nuclear structure configuration among the isotopes. The anapole is a unique probe of the weak interaction in the presence of the strong interaction. The system is currently being tested with rubidium and we have analyzed the sensitivity to measurements with a chain of Rb isotopes. Our experimental scheme involves a collection of cold atoms in a blue-detuned dipole trap located at the anti-node of a microwave cavity. The standing wave would drive a parity forbidden E1 transition between hyperfine ground states, interfering with an allowed transition. The rate of transitions depends on the positive or negative handedness of the apparatus and the measurement of their difference is proportional to the anapole moment. The experiment will use of the ISAC radioactive beam facility at TRIUMF. )
Temperature Measurements in the Magnetic Measurement Facility
Wolf, Zachary
2010-12-13
Several key LCLS undulator parameter values depend strongly on temperature primarily because of the permanent magnet material the undulators are constructed with. The undulators will be tuned to have specific parameter values in the Magnetic Measurement Facility (MMF). Consequently, it is necessary for the temperature of the MMF to remain fairly constant. Requirements on undulator temperature have been established. When in use, the undulator temperature will be in the range 20.0 {+-} 0.2 C. In the MMF, the undulator tuning will be done at 20.0 {+-} 0.1 C. For special studies, the MMF temperature set point can be changed to a value between 18 C and 23 C with stability of {+-}0.1 C. In order to ensure that the MMF temperature requirements are met, the MMF must have a system to measure temperatures. The accuracy of the MMF temperature measurement system must be better than the {+-}0.1 C undulator tuning temperature tolerance, and is taken to be {+-}0.01 C. The temperature measurement system for the MMF is under construction. It is similar to a prototype system we built two years ago in the Sector 10 alignment lab at SLAC. At that time, our goal was to measure the lab temperature to {+-}0.1 C. The system has worked well for two years and has maintained its accuracy. For the MMF system, we propose better sensors and a more extensive calibration program to achieve the factor of 10 increase in accuracy. In this note we describe the measurement system under construction. We motivate our choice of system components and give an overview of the system. Most of the software for the system has been written and will be discussed. We discuss error sources in temperature measurements and show how these errors have been dealt with. The calibration system is described in detail. All the LCLS undulators must be tuned in the Magnetic Measurement Facility at the same temperature to within {+-}0.1 C. In order to ensure this, we are building a system to measure the temperature of the
Anomalous magnetic moment contributions to NN bremsstrahlung in the soft-photon approximation
Gibson, B.F.; Penninga, T.D.; Timmermans, R.G.E.; Liou, M.K.
2005-05-06
The soft photon approximation (SPA), which is relativistic and based upon a fundamental theorem for photon emission, is applied to explore two separate nucleon-nucleon bremsstrahlung (NN{gamma}) processes: pp{gamma} and np{gamma}. They are examined together in an effort to understand the mechanism which governs photon emission from these basic two-nucleon systems. In this investigation we focus upon the effect of the anomalous magnetic moments of the proton ({kappa}p) and the neutron ({kappa}n). In our SPA calculation we use the standard Low amplitude M{sub {mu}}{sup Low} as derived by Nyman plus the more recently developed amplitude M{sub {mu}}{sup TuTts}, referred to as the two-u-two-t special (TuTts) amplitude. The amplitude M{sub {mu}}{sup TuTts} is identical to the amplitude M{sub {mu}}{sup Low} through order K0 in the soft-photon expansion. However, M{sub {mu}}{sup TuTts} includes an additional term M{sub {mu}}{sup (3)}(K{sup 1}; {kappa}) (plus higher order terms). The term M{sub {mu}}{sup (3)}(K{sup 1}; {kappa}) is of order K1 in the soft-photon expansion and it is a function of {kappa}p and {kappa}n. Using the amplitudes M{sub {mu}}{sup TuTts} and M{sub {mu}}{sup Low}, we have calculated pp{gamma} and np{gamma} cross sections as a function of photon angle {psi}{gamma} with and without contributions from {kappa}p and {kappa}n. Comparison with available pp{gamma} data has been made; in particular, the contribution from M{sub {mu}}{sup (3)}(K{sup 1}; {kappa}) has been investigated. Results will be presented and discussed which relate to the following: (i) The anomalous magnetic moment effect is significant in pp{gamma}; however, it is small in np{gamma}. That is, the two amplitudes M{sub {mu}}{sup TuTts} and M{sub {mu}}{sup Low} yield very similar np{gamma} cross sections, but they predict very different pp{gamma} cross sections. (ii) M{sub {mu}}{sup TuTts} appears to provide a better SPA than M{sub {mu}}{sup Low} in the case of pp{gamma}. Because {kappa
Yang, X F; Wraith, C; Xie, L; Babcock, C; Billowes, J; Bissell, M L; Blaum, K; Cheal, B; Flanagan, K T; Garcia Ruiz, R F; Gins, W; Gorges, C; Grob, L K; Heylen, H; Kaufmann, S; Kowalska, M; Kraemer, J; Malbrunot-Ettenauer, S; Neugart, R; Neyens, G; Nörtershäuser, W; Papuga, J; Sánchez, R; Yordanov, D T
2016-05-01
Collinear laser spectroscopy is performed on the _{30}^{79}Zn_{49} isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life is confirmed, and the nuclear spins and moments of the ground and isomeric states in ^{79}Zn as well as the isomer shift are measured. From the observed hyperfine structures, spins I=9/2 and I=1/2 are firmly assigned to the ground and isomeric states. The magnetic moment μ (^{79}Zn)=-1.1866(10)μ_{N}, confirms the spin-parity 9/2^{+} with a νg_{9/2}^{-1} shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment μ (^{79m}Zn)=-1.0180(12)μ_{N} supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the N=50 shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state, δ⟨r_{c}^{2}⟩^{79,79m}=+0.204(6) fm^{2}, providing first evidence of shape coexistence.
Yang, X F; Wraith, C; Xie, L; Babcock, C; Billowes, J; Bissell, M L; Blaum, K; Cheal, B; Flanagan, K T; Garcia Ruiz, R F; Gins, W; Gorges, C; Grob, L K; Heylen, H; Kaufmann, S; Kowalska, M; Kraemer, J; Malbrunot-Ettenauer, S; Neugart, R; Neyens, G; Nörtershäuser, W; Papuga, J; Sánchez, R; Yordanov, D T
2016-05-01
Collinear laser spectroscopy is performed on the _{30}^{79}Zn_{49} isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life is confirmed, and the nuclear spins and moments of the ground and isomeric states in ^{79}Zn as well as the isomer shift are measured. From the observed hyperfine structures, spins I=9/2 and I=1/2 are firmly assigned to the ground and isomeric states. The magnetic moment μ (^{79}Zn)=-1.1866(10)μ_{N}, confirms the spin-parity 9/2^{+} with a νg_{9/2}^{-1} shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment μ (^{79m}Zn)=-1.0180(12)μ_{N} supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the N=50 shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state, δ⟨r_{c}^{2}⟩^{79,79m}=+0.204(6) fm^{2}, providing first evidence of shape coexistence. PMID:27203317
NASA Astrophysics Data System (ADS)
Yang, X. F.; Wraith, C.; Xie, L.; Babcock, C.; Billowes, J.; Bissell, M. L.; Blaum, K.; Cheal, B.; Flanagan, K. T.; Garcia Ruiz, R. F.; Gins, W.; Gorges, C.; Grob, L. K.; Heylen, H.; Kaufmann, S.; Kowalska, M.; Kraemer, J.; Malbrunot-Ettenauer, S.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Papuga, J.; Sánchez, R.; Yordanov, D. T.
2016-05-01
Collinear laser spectroscopy is performed on the 30,79Zn49 isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life is confirmed, and the nuclear spins and moments of the ground and isomeric states in 79Zn as well as the isomer shift are measured. From the observed hyperfine structures, spins I =9 /2 and I =1 /2 are firmly assigned to the ground and isomeric states. The magnetic moment μ (79Zn)=-1.1866 (10 )μN , confirms the spin-parity 9 /2+ with a ν g9/2 -1 shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment μ (Znm79)=-1.0180 (12 )μN supports a positive parity for the isomer, with a wave function dominated by a 2 h -1 p neutron excitation across the N =50 shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state, δ ⟨rc2⟩79 ,79 m=+0.204 (6 ) fm2 , providing first evidence of shape coexistence.
The third central moment of photospheric lines as a measure of velocity gradients and line shifts
NASA Astrophysics Data System (ADS)
Marmolino, C.; Severino, G.
1981-07-01
The significance of the third central moment (M3) of photospheric line profiles as an indicator of velocity, temperature and pressure perturbations is analyzed. A linear inversion method is applied to the third central moments of a set of synthetic lines computed using the temperature structures of the B2 and D2 models of Altrock and Musman (1976) for the granular and intergranular atmospheres, respectively, in order to derive mean photospheric velocity gradients. It is found that for data taken with infinite spatial resolution, M3 is a nearly linear measure of the velocity gradients, whereas at finite resolution it is essentially determined by the different weights of the shifted granular and intergranular line components. Results also suggest a means of disentangling velocity gradients and the horizontal integration of inhomogeneities.
A new method to measure torsion moments on small-scaled specimens.
Walter, M; Kraft, O
2011-03-01
As a result of a continuous evolution in the field of small-scaled components, an increasing need exists for mechanical characterization of single structures and materials in micrometer dimensions. Moreover, for a detailed analysis of the deformation and failure behavior, it is often necessary to perform investigations under multiaxial loading in addition to uniaxial loading. A simple possibility to create defined multiaxial stress-strain fields is offered by a torsion experiment. In the frame of this work, a new method is presented, which allows determining torsion moments applied to wires as thin as 10 μm in monotonic as well as cyclic manner. Besides a detailed description of the measuring principle, the experimental setup and the first results will be presented. In particular, investigations on gold wires with diameters ranging from 10 to 60 μm, applying torsion moments in the nNm regime, are shown.
A new method to measure torsion moments on small-scaled specimens
Walter, M.; Kraft, O.
2011-03-15
As a result of a continuous evolution in the field of small-scaled components, an increasing need exists for mechanical characterization of single structures and materials in micrometer dimensions. Moreover, for a detailed analysis of the deformation and failure behavior, it is often necessary to perform investigations under multiaxial loading in addition to uniaxial loading. A simple possibility to create defined multiaxial stress-strain fields is offered by a torsion experiment. In the frame of this work, a new method is presented, which allows determining torsion moments applied to wires as thin as 10 {mu}m in monotonic as well as cyclic manner. Besides a detailed description of the measuring principle, the experimental setup and the first results will be presented. In particular, investigations on gold wires with diameters ranging from 10 to 60 {mu}m, applying torsion moments in the nNm regime, are shown.
NASA Astrophysics Data System (ADS)
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.
Magnetic moment for the negative parity Λ → Σ0 transition in light cone QCD sum rules
NASA Astrophysics Data System (ADS)
Aliev, T. M.; Savcı, M.
2016-07-01
The magnetic moment of the Λ →Σ0 transition between negative parity baryons is calculated in framework of the QCD sum rules approach by using the general form of the interpolating currents. The pollution arising from the positive-to-positive, and positive-to-negative parity baryons is eliminated by constructing the sum rules for different Lorentz structures. A comparison of our result with the predictions of the results of other approaches for the positive parity baryons is presented.
A to Z of the muon anomalous magnetic moment in the MSSM with Pati-Salam at the GUT scale
NASA Astrophysics Data System (ADS)
Belyaev, Alexander S.; Camargo-Molina, José E.; King, Steve F.; Miller, David J.; Morais, António P.; Schaefers, Patrick B.
2016-06-01
We analyse the low energy predictions of the minimal supersymmetric standard model (MSSM) arising from a GUT scale Pati-Salam gauge group further constrained by an A 4 × Z 5 family symmetry, resulting in four soft scalar masses at the GUT scale: one left-handed soft mass m 0 and three right-handed soft masses m 1 , m 2 , m 3, one for each generation. We demonstrate that this model, which was initially developed to describe the neutrino sector, can explain collider and non-collider measurements such as the dark matter relic density, the Higgs boson mass and, in particular, the anomalous magnetic moment of the muon ( g - 2) μ . Since about two decades, ( g - 2) μ suffers a puzzling about 3 σ excessoftheexperimentallymeasuredvalueoverthetheoreticalprediction,whichour model is able to fully resolve. As the consequence of this resolution, our model predicts specific regions of the parameter space with the specific properties including light smuons and neutralinos, which could also potentially explain di-lepton excesses observed by CMS and ATLAS.
NASA Astrophysics Data System (ADS)
Yang, Hongxin; Chshiev, Mairbek; Spintec Team
2011-03-01
First-principles calculations of electronic and magnetic properties of pure and H-terminated graphene nanomesh (GNM) are presented. We found stable antiferromagnetic and non-magnetic ground state for GNM with balanced zigzag and armchair-type edge structures, respectively. At the same time, a band gap opening in the balanced zigzag edge GNMs which can reach up to 0.40 eV is also found. Interestingly, GNM with unbalanced edge structure shows stable ferrimagnetic state giving rise to a net moment up to 4 Bohr magnetons per unit cell, and the exchange energy between ferrimagnetic state and paramagnetic state is larger than 1 eV per unit cell providing potential for high Curie temperature in this material. Furthermore, we found that the ground states for H-terminated GNM strongly depend on the hole symmetry: large spin polarization ground state is found for GNMs with triangle and pentagon hole shapes, while for GNMs with parallelogram and hexagon shaped holes the ground states are paramagnetic. Finally, we found that the magnetization of the GNM structure is strongly affected by the hole size: the larger hole size attains large moments, while small one may even kill all the moments.
NASA Astrophysics Data System (ADS)
Nakajo, Hiroshi; Takahashi, Yukihiro; Hiromi, Kase; Adachi, Toru; Sato, Mitsuteru; Yamashita, Kozo
channels arrayed in the vertical direction. The output of each channel is recorded at a sampling frequency of 2 kHz or 20 kHz. Thus, the AP can measure temporal and vertical structure of sprites. We are able to estimate sprite luminous intensity from AP data. Our team operates a worldwide ELF observation network, consisting of four observation sites located at Syowa in Antarctica, Onagawa in Japan, Kiruna in Swe-den, and California in US. Observation system at each site records ELF magnetic waveforms in the wavelength range of 1-100 Hz continuously. We can estimate the lightning location and the charge moment for intense lightning events whose charge moment is larger than 350 Ckm. We estimate lightning charge moment from ELF data and sprite luminous intensity from AP data. We analyze 12 events of sprite-halos observed from July 2004 to October 2005. The averages of the time-integrated luminous intensity are 9.0*102 2photonsf orN 21P Gand1.3∗ 102 2photonsf orN 22P Gbands, respectively.W eshowthereispositivecorrelationbetweentheopticalenergies 0.76), whichdoesnotconf lictwithastoryof QEmodelqualitatively.W ewillanalyzemoreeventstodiscussregi
On measure solutions of the Boltzmann equation, part I: Moment production and stability estimates
NASA Astrophysics Data System (ADS)
Lu, Xuguang; Mouhot, Clément
The spatially homogeneous Boltzmann equation with hard potentials is considered for measure valued initial data having finite mass and energy. We prove the existence of weak measure solutions, with and without angular cutoff on the collision kernel; the proof in particular makes use of an approximation argument based on the Mehler transform. Moment production estimates in the usual form and in the exponential form are obtained for these solutions. Finally for the Grad angular cutoff, we also establish uniqueness and strong stability estimate on these solutions.
NASA Astrophysics Data System (ADS)
Bialynicki-Birula, Iwo; RadoŻycki, Tomasz
2016-06-01
The motion of a neutral atom endowed with a magnetic moment interacting with the magnetic field is determined from the Ehrenfest-like equations of motion. These equations for the average values of the translational and spin degrees of freedom are derived from the Schrödinger-Pauli wave equation, and they form a set of nine coupled nonlinear evolution equations. The numerical and analytic solutions of these equations are obtained for the combination of the rotating magnetic field of a wave carrying orbital angular momentum and a static magnetic field. The running wave traps the atom only in the transverse direction, while the standing wave traps the atom also in the direction of the beam.
NASA Astrophysics Data System (ADS)
de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.
2008-04-01
In this work, we theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a Mösbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced magnetic moments arising from the Co neighboring sites. Our calculated self-consistent total magnetic hyperfine fields are in a good agreement with recent experimental data.
R&D ERL: Magnetic measurements of the ERL magnets
Jain, A.
2010-08-01
The magnet system of ERL consists of G5 solenoids, 6Q12 quadrupoles with 0.58 T/m gradient, 3D60 dipoles with 0.4 T central field, 15 and 30 degree Z-bend injection line dipole/quadrupole combined function magnets, and extraction line magnets. More details about the magnets can be found in a report by G. Mahler. Field quality in all the 6Q12 quadrupoles, 3D60 dipoles and the injection line magnets has been measured with either a rotating coil, or a Hall probe mapper. This report presents the results of these magnetic measurements.
Static and dynamic force/moment measurements in the Eidetics water tunnel
NASA Technical Reports Server (NTRS)
Suarez, Carlos J.; Malcolm, Gerald N.
1994-01-01
Water tunnels have been utilized in one form or another to explore fluid mechanics and aerodynamics phenomena since the days of Leonardo da Vinci. Water tunnel testing is attractive because of the relatively low cost and quick turn-around time to perform flow visualization experiments and evaluate the results. The principal limitation of a water tunnel is that the low flow speed, which provides for detailed visualization, also results in very small hydrodynamic (aerodynamic) forces on the model, which, in the past, have proven to be difficult to measure accurately. However, the advent of semi-conductor strain gage technology and devices associated with data acquisition such as low-noise amplifiers, electronic filters, and digital recording have made accurate measurements of very low strain levels feasible. The principal objective of this research effort was to develop a multi-component strain gage balance to measure forces and moments on models tested in flow visualization water tunnels. A balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The balance mounts internally in the model and is used in a manner typical of wind tunnel balances. The key differences between a water tunnel balance and a wind tunnel balance are the requirement for very high sensitivity since the loads are very low (typical normal force is 0.2 lbs), the need for water proofing the gage elements, and the small size required to fit into typical water tunnel models.
A general way for quantitative magnetic measurement by transmitted electrons
Song, Dongsheng; Li, Gen; Cai, Jianwang; Zhu, Jing
2016-01-01
EMCD (electron magnetic circular dichroism) technique opens a new door to explore magnetic properties by transmitted electrons. The recently developed site-specific EMCD technique makes it possible to obtain rich magnetic information from the Fe atoms sited at nonequivalent crystallographic planes in NiFe2O4, however it is based on a critical demand for the crystallographic structure of the testing sample. Here, we have further improved and tested the method for quantitative site-specific magnetic measurement applicable for more complex crystallographic structure by using the effective dynamical diffraction effects (general routine for selecting proper diffraction conditions, making use of the asymmetry of dynamical diffraction for design of experimental geometry and quantitative measurement, etc), and taken yttrium iron garnet (Y3Fe5O12, YIG) with more complex crystallographic structure as an example to demonstrate its applicability. As a result, the intrinsic magnetic circular dichroism signals, spin and orbital magnetic moment of iron with site-specific are quantitatively determined. The method will further promote the development of quantitative magnetic measurement with high spatial resolution by transmitted electrons. PMID:26726959
A general way for quantitative magnetic measurement by transmitted electrons.
Song, Dongsheng; Li, Gen; Cai, Jianwang; Zhu, Jing
2016-01-01
EMCD (electron magnetic circular dichroism) technique opens a new door to explore magnetic properties by transmitted electrons. The recently developed site-specific EMCD technique makes it possible to obtain rich magnetic information from the Fe atoms sited at nonequivalent crystallographic planes in NiFe2O4, however it is based on a critical demand for the crystallographic structure of the testing sample. Here, we have further improved and tested the method for quantitative site-specific magnetic measurement applicable for more complex crystallographic structure by using the effective dynamical diffraction effects (general routine for selecting proper diffraction conditions, making use of the asymmetry of dynamical diffraction for design of experimental geometry and quantitative measurement, etc), and taken yttrium iron garnet (Y3Fe5O12, YIG) with more complex crystallographic structure as an example to demonstrate its applicability. As a result, the intrinsic magnetic circular dichroism signals, spin and orbital magnetic moment of iron with site-specific are quantitatively determined. The method will further promote the development of quantitative magnetic measurement with high spatial resolution by transmitted electrons.
Updated measurement of the permanent electric dipole moment (EDM) of 199Hg
NASA Astrophysics Data System (ADS)
Graner, Brent; Chen, Yi; Lindahl, Eric; Heckel, Blayne
2016-03-01
A permanent electric dipole moment (EDM) in an atom or particle would prove that time reversal symmetry is broken. In addition, an atomic EDM may provide evidence of new physics or CP symmetry violation in the strong sector. We have recently completed an improved measurement of the EDM of 199Hg utilizing a set of vapor cells containing isotopically-enriched 199Hg optically pumped and probed with UV laser light. I will discuss the most recent iteration of the experiment, and present unblinded results. This work was supported by NSF Grant 1306743 and DOE Award No. DE-FG02-97ER41020.
Atomic Spin Squeezing Towards Sub-Shot-Noise Measurement Of Permanent Electric Dipole Moment
Takano, T.; Fuyama, M.; Yamamoto, H.; Takahashi, Y.
2007-06-13
We have been studying laser-cooled and trapped atoms towards the detection of the permanent electric dipole moment (p-EDM). The existence of the p-EDM shows the CP-violation and its detection has significant implications for the test of the proposed elementary particle models. However, the current experimental accuracy has not yet reached the range of the predicted value of the standard model. Especially, a measurement error due to a shot noise is one of the important factors. To overcome the shot-noise limit, we are now trying to generate the atomic squeezed spin state.
Updated measurement of the permanent electric dipole moment (EDM) of 199 Hg
NASA Astrophysics Data System (ADS)
Graner, Brent; Chen, Yi; Lindahl, Eric; Heckel, Blayne
2016-05-01
A permanent electric dipole moment (EDM) in an atom or particle would prove that time reversal symmetry is broken. In addition, an atomic EDM may provide evidence of new physics or CP symmetry violation in the strong sector. We have recently completed an improved measurement of the EDM of 199 Hg utilizing a set of vapor cells containing isotopically-enriched 199 Hg optically pumped and probed with UV laser light. I will discuss the most recent iteration of the experiment, and present unblinded results. This work was supported by NSF Grant 1306743 and DOE Award No. DE-FG02-97ER41020.
NASA Astrophysics Data System (ADS)
Brewer, Marilee Ann
Intense scientific and technological interest in iron nitrides has persisted since saturation magnetizations much larger than that of alpha-Fe (1708 emu/cmsp3) were reported for the metastable alphasp{''}-Fesb{16}Nsb2 phase (2300 emu/cmsp3) grown by MBE on lattice-matched substrates. Most attempts at growing alphasp{''} using technologically-relevant deposition processes and substrates have resulted in only a modest enhancement in moment, and are complicated by competition from more stable FeN phases. Furthermore, conventional band theory calculations for alphasp{''} (1780 emu/cmsp3) do not predict a "giant" magnetic moment. We have grown several phases of FeN on Si(001) by lattice matching on Ag underlayers. Optimization of reactive Nsb2 sputtering parameters has led to the growth of alpha-Fe, gammasp''-Fesb4N and alphasp'-Fesb8N films. Annealing of N-disordered alphasp'-Fesb8N films resulted in partial transformation to N-ordered alphasp{''}-Fesb{16}Nsb2. Quantification of X-ray diffraction peak intensities determined that the alphasp'/alphasp{''} mixtures contained 48 vol% alphasp{''} (remaining alphasp'). Selected-area diffraction (SAD) in the TEM determined that the orientation relationships of the alpha,\\ alphasp', and alphasp{''} phases were FeN(001)VertAg(001)VertSi(001) and FeN(100) VertAg(110) VertSi(100), while the in-plane orientation of gammasp'(001) was FeN(110) VertAg(110) VertSi(100). Electron energy-loss spectroscopy (EELS) determined that the FeN films were stoichiometrically correct and there was no significant change in N content with annealing. Vibrating-sample magnetometry of the alphasp' and alphasp'/alphasp{''} films measured a saturation magnetization of 1780 emu/cmsp3 for both phases; there was no change in the magnetization with increasing N order and no giant moment. Mossbauer spectroscopy of the alphasp'/alphasp{''} films confirmed the presence of three chemically-inequivalent iron sites with the expected occupancy ratio for Fe
NASA Astrophysics Data System (ADS)
McHenry, M. E.; MacLaren, J. M.; Clougherty, D. P.
1991-11-01
Electronic and magnetic properties of T/Aun, T/Agn (T=Cr, Mn, Fe, Co, and Ni), Fe/Pdn and Fe/Ptn multilayers and sandwiches have been computed using the layer Korringa-Kohn-Rostoker (LKKR) band-structure technique. Enhanced (as compared with bulk) 2D T magnetism is observed in all Cr, Mn, and Fe/host configurations, consistent with weak coupling between Cr, Mn, and Fe d bands and those of the noble metal (NM) hosts and consequently d bandwidths which are exceeded by the exchange splitting. Fe and Cr moments vary systematically with the number of mediating Ag or Au planes and the Fermi energy of the system. These systematics are explained by considering the variation of the Fermi energy (EF) with composition as well as constraints of charge neutrality and strong (single-band) ferromagnetism. For Fe in Pt and Pd hosts, d-d hybridization leads to a nearly invariant Fe moment as a function of the number of mediating Pd or Pt planes but with large induced moments on the host.
Lydon, T.J.; Sofia, S.
1996-01-01
The Solar Disk Sextant experiment has measured the solar angular diameter for a variety of solar latitudes. Combined with solar surface angular rotation data, the solar quadrupole moment {ital J}{sub 2} and the solar octopole moment {ital J}{sub 4} have been derived first by assuming constant internal angular rotation on cylinders and then by assuming constant internal angular rotation on cones. We have derived values of 1.8{times}10{sup {minus}7} for {ital J}{sub 2} and 9.8{times}10{sup {minus}7} for {ital J}{sub 4}. We conclude with a discussion of errors and address the prediction of general relativity for the rate of advance of perihelion of the planet Mercury. {copyright} {ital 1996 The American Physical Society.}
Helled, R.
2011-07-01
Knowledge of Saturn's axial moment of inertia can provide valuable information on its internal structure. We suggest that Saturn's angular momentum may be determined by the Solstice Mission (Cassini XXM) by measuring Saturn's pole precession rate and the Lense-Thirring acceleration on the spacecraft, and therefore put constraints on Saturn's moment of inertia. It is shown that Saturn's moment of inertia can change up to {approx}2% due to different core properties. However, a determination of Saturn's rotation rate is required to constrain its axial moment of inertia. A change of about seven minutes in rotation period leads to a similar uncertainty in the moment of inertia value as different core properties (mass, radius). A determination of Saturn's angular momentum and rotation period by the Solstice Mission could reveal important information on Saturn's internal structure, in particular, its core properties.
NASA Astrophysics Data System (ADS)
Kawski, A.; Kukliński, B.; Bojarski, P.
2006-07-01
The effect of temperature on absorption and fluorescence spectra of 4-aminobenzonitrile (ABN) in 1,2-dichloroethane is studied for temperature ranging from 296 K to 343 K. The analysis of absorption and fluorescence band shift on the basis of Bilot and Kawski theory [L. Bilot, A. Kawski, Z. Naturforsch. 17a (1962) 621], for the known dipole moment in the ground state μg = 5.92 D, and α/ a3 = 0.5 ( α is the polarizability and a is the Onsager interaction radius of the solute) yields for ABN: (1) the empirical Onsager interaction radius a = 3.3 Å, (2) the dipole moment in the excited S 1 state μe = 7.14 D which agrees very well with the value of μe = 7.20 D obtained by Borst et al. [D.R. Borst, T.M. Korter, D.W. Pratt, Chem. Phys. Lett. 350 (2001) 485] from Stark effect studies. Both values of μe concern free ABN molecule and differ significantly from the values of μg (8.0 D, 8.5 D and 8.3 D in cyclohexane, benzene and 1,4-dioxane, respectively) obtained by Schuddeboom et al. [W. Schuddeboom, S.A. Jonker, J.M. Warman, U. Leinhos, W. Kühnle, K.A. Zachariasse, J. Phys. Chem. 96 (1992) 10809] from the time-resolved microwave conductivity measurements which are solvent-dependent. The group moment additivity law in the case of ABN molecule is approximately applicable, both in the ground and in the excited electronic state.
NASA Astrophysics Data System (ADS)
Tabar, Emre; Yakut, Hakan; Kuliev, Ali Akbar
2016-07-01
The ground state magnetic moments and the low-lying magnetic dipole (Ml) transitions from the ground to excited states in heavy deformed odd-mass 181Ta have been microscopically investigated on the basis of the quasiparticle-phonon nuclear model (QPNM). The problem of the spurious state mixing in M1 excitations is overcome by a restoration method allowing a self-consistent determination of the separable effective restoration forces. Due to the self-consistency of the method, these effective forces contain no arbitrary parameters. The results of calculations are compared with the available experimental data, the agreement being reasonably satisfactory.
Ledwig, Tim; Silva, Antonio
2010-09-01
We investigate the form factors of the chiral-odd nucleon matrix element of the tensor current. In particular, we aim at the anomalous tensor magnetic form factors of the nucleon within the framework of the SU(3) and SU(2) chiral quark-soliton model. We consider 1/N{sub c} rotational corrections and linear effects of SU(3) symmetry breaking with the symmetry-conserving quantization employed. We first obtain the results of the anomalous tensor magnetic moments for the up and down quarks: {kappa}{sub T}{sup u}=3.56 and {kappa}{sub T}{sup d}=1.83, respectively. The strange anomalous tensor magnetic moment is yielded to be {kappa}{sub T}{sup s}=0.2{approx}-0.2, that is compatible with zero. We also calculate the corresponding form factors {kappa}{sub T}{sup q}(Q{sup 2}) up to a momentum transfer Q{sup 2{<=}}1 GeV{sup 2} at a renormalization scale of 0.36 GeV{sup 2}.
Single Cell Magnetic Measurements with a Superconducting Quantum Interference Device
NASA Astrophysics Data System (ADS)
Palmstrom, Johanna C.; Arps, Jennifer; Dwyer, Bo; Kalisky, Beena; Kirtley, John R.; Moler, Kathryn A.; Qian, Lisa C.; Rosenberg, Aaron J.; Rutt, Brian; Tee, Sui Seng; Theis, Eric; Urbach, Elana; Wang, Yihua
2014-03-01
Magnetic nanoparticles play an important role in numerous biomedical applications such as magnetic resonance imaging and targeted drug delivery. There is a need for tools to characterize individual magnetic nanoparticles and the magnetic properties of individual cells. We use a scanning superconducting quantum interference device (SQUID) to observe the magnetic fields from single mammalian cells loaded with superparamagnetic iron oxide nanoparticles. We show that the SQUID is a useful tool for imaging biological magnetism and is capable of resolving cell to cell variations in magnetic dipole moments. We hope to correlate these magnetic images with real space imaging techniques such as optical and scanning electron microscopy. The visualization of single cell magnetism can be used to optimize biological magnetic imaging techniques, such as MRI, by quantifying the strength of magnetic dipole moments of in vitro magnetic labeling. This work is supported by a National Science Foundation Graduate Research Fellowship and a Gabilan Stanford Graduate Fellowship.
Manz, Thomas A; Sholl, David S
2011-12-13
The partitioning of electron spin density among atoms in a material gives atomic spin moments (ASMs), which are important for understanding magnetic properties. We compare ASMs computed using different population analysis methods and introduce a method for computing density derived electrostatic and chemical (DDEC) ASMs. Bader and DDEC ASMs can be computed for periodic and nonperiodic materials with either collinear or noncollinear magnetism, while natural population analysis (NPA) ASMs can be computed for nonperiodic materials with collinear magnetism. Our results show Bader, DDEC, and (where applicable) NPA methods give similar ASMs, but different net atomic charges. Because they are optimized to reproduce both the magnetic field and the chemical states of atoms in a material, DDEC ASMs are especially suitable for constructing interaction potentials for atomistic simulations. We describe the computation of accurate ASMs for (a) a variety of systems using collinear and noncollinear spin DFT, (b) highly correlated materials (e.g., magnetite) using DFT+U, and (c) various spin states of ozone using coupled cluster expansions. The computed ASMs are in good agreement with available experimental results for a variety of periodic and nonperiodic materials. Examples considered include the antiferromagnetic metal organic framework Cu3(BTC)2, several ozone spin states, mono- and binuclear transition metal complexes, ferri- and ferro-magnetic solids (e.g., Fe3O4, Fe3Si), and simple molecular systems. We briefly discuss the theory of exchange-correlation functionals for studying noncollinear magnetism. A method for finding the ground state of systems with highly noncollinear magnetism is introduced. We use these methods to study the spin-orbit coupling potential energy surface of the single molecule magnet Fe4C40H52N4O12, which has highly noncollinear magnetism, and find that it contains unusual features that give a new interpretation to experimental data.
Measurements of Solar Vector Magnetic Fields
NASA Technical Reports Server (NTRS)
Hagyard, M. J. (Editor)
1985-01-01
Various aspects of the measurement of solar magnetic fields are presented. The four major subdivisions of the study are: (1) theoretical understanding of solar vector magnetic fields; (3) techniques for interpretation of observational data; and (4) techniques for data display.
Theulé, Patrice; Callegari, Andrea; Rizzo, Thomas R; Muenter, John S
2005-03-22
We report here a measurement of electric dipole moments in highly vibrationally excited HDO molecules. We use photofragment yield detected quantum beat spectroscopy to determine electric field induced splittings of the J=1 rotational levels of HDO excited with 4, 5, and 8 quanta of vibration in the OH stretching mode. The splittings allow us to deduce mua and mub, the projections of dipole moment onto the molecular rotation inertial axes. We compare the measured HDO dipole moment components with the results of quantitative calculations based on Morse oscillator wave functions and an ab initio dipole moment surface. The vibrational dependence of the dipole moment components reflect both structural and electronic changes in HDO upon vibrational excitation; principally the vibrational dependence of the O-H bond length and bond angle, and the resulting change in orientation of the principal inertial coordinate system. The dipole moment data also provide a sensitive test of theoretical dipole moment and potential energy surfaces, particularly for molecular configurations far from equilibrium.
NASA Astrophysics Data System (ADS)
Bosch-Santos, B.; Carbonari, A. W.; Cabrera-Pasca, G. A.; Saxena, R. N.; Freitas, R. S.
2015-05-01
The magnetic behavior of the intermetallic compound NdMn2Ge2 was investigated by bulk magnetization measurements and measurements of hyperfine interactions using perturbed γ-γ angular correlation (PAC) spectroscopy. Magnetization measurements indicate the presence of four magnetic transitions associated with the Mn and Nd magnetic sublattices. At high temperatures, magnetic measurements show a change in the slope of the magnetization due to an antiferromagnetic transition around TN ˜ 425 K and a well defined ferromagnetic transition at TC ˜ 320 K. Moreover, at ˜210 K a peak is observed in the magnetization curve, which is assigned to the reorientation of the Mn spin, and at ˜25 K an increase in the magnetic moment is also observed, which is ascribed to the ordering of Nd ions. PAC measurements using 140La(140Ce) and 111In(111Cd) probe nuclei allowed the determination of the temperature dependence of the magnetic hyperfine field (Bhf) at Nd and Mn sites, respectively. PAC results with 111Cd probe nuclei at Mn sites show that the dependence of Bhf with temperature follows the expected behavior for the host magnetization associated with the magnetic ordering of Mn ions. From these results, the antiferromagnetic transition followed by a ferromagnetic ordering is clearly observed. PAC results with 140Ce probe nuclei at Nd sites, however, showed a strong deviation from the Brillouin function, which is attributed to the Ce 4f-electron contribution to Bhf.
NASA Astrophysics Data System (ADS)
Ri, Euijae
Some magnetic characteristics of Nd-Fe-B sintered magnets have been clarified, especially in the near vicinity within three times their length for cylindrical magnets. The flux densities as a function of distance (z) along the z-axis from the center of a single magnet were determined by utilizing Hall sensors. The repulsions between two magnets possessing identical shape were directly measured, also as a function of z, by using a home-made apparatus adopting piezoelectric device. The respective result has turned out well, coinciding with that of corresponding finite element method analysis and some analytical solutions. Also in this investigation, the correct formula directly applicable to the near H-field strength along the magnetic moment of a cylindrical magnet has been determined to be the exact solution that defies all confusing approximations or assumptions in theory, which were seen in textbooks or published in papers. Furthermore an analytical solution for the repulsion of magnet twins (cylindrical or hexagonal in shape), which can be handy in designing a variety of superconducting and/or electromagnetic devices, has been derived basically from Biot-Savart Law.
NASA Astrophysics Data System (ADS)
Zhou, Z.; Beguhn, S.; Lou, J.; Rand, S.; Li, M.; Yang, X.; Li, S. D.; Liu, M.; Sun, N. X.
2012-05-01
Magnetic/piezoelectric multiferroic heterostructures with a magnetic thin film on a piezoelectric slab provides a great opportunity to achieve a strong converse magnetoelectric coupling with great potential for voltage tunable magnetic devices. Efforts have been made in developing highly magnetostrictive RF magnetic materials with low magnetization using magnetic/piezoelectric heterostructures to generate large electric-field induced effective magnetic fields. In this work, we report on NiCr films having low magnetization and relatively large magnetostriction. Strong converse magnetoelectric coupling and large electric field tunable ferromagnetic resonance (FMR) bandwidths are achieved in layered NiCr/lead zirconate titanate (PZT) and NiCr/lead zinc niobate lead titanate (PZN-PT) multiferroic heterostructures. A large electric field induced effective magnetic field of 260 Oe for NiCr/PZT and 756 Oe for NiCr/PZN-PT was observed, corresponding to a giant magnetoelectric coupling coefficient of 13 Oe cm/kV in NiCr/PZT and 75.6 Oe cm/kV in NiCr/PZN-PT multiferroic heterostructures. A high voltage tunable FMR frequency range was observed, with fmax/fmin being 124 and 325% for NiCr/PZT and NiCr/PZN-PT. The strong converse magnetoelectric coupling of NiCr/PZT and NiCr/PZN-PT heterostructures provide great opportunities for electric field tunable RF magnetic devices.
NASA Technical Reports Server (NTRS)
Bortolussi, Michael R.; Hart, Sandra G.; Shively, Robert J.
1987-01-01
A simulation was conducted to determine whether the sensitivity of secondary task measures of pilot workload could be improved by synchronizing their presentation to the occurrence of specific events or pilot actions. This synchronous method of presentation was compared to the more typical asynchronous method, where secondary task presentations are independent of pilot's flight-related activities. Twelve pilots flew low- and high-difficulty scenarios in a motion-base trainer with and without concurrent secondary tasks (e.g., choice reaction time and time production). The difficulty of each scenario was manipulated by the addition of 21 flight-related tasks superimposed on a standard approach and landing sequence. The insertion of the secondary tasks did not affect primary flight performance. However, secondary task performance did reflect workload differences between scenarios and among flight segments within scenarios, replicating the results of an earlier study in which the secondary tasks were presented asynchronously (Bortolussi et al., 1986).
NASA Technical Reports Server (NTRS)
Eskins, Jonathan
1988-01-01
The problem of determining the forces and moments acting on a wind tunnel model suspended in a Magnetic Suspension and Balance System is addressed. Two calibration methods were investigated for three types of model cores, i.e., Alnico, Samarium-Cobalt, and a superconducting solenoid. Both methods involve calibrating the currents in the electromagnetic array against known forces and moments. The first is a static calibration method using calibration weights and a system of pulleys. The other method, dynamic calibration, involves oscillating the model and using its inertia to provide calibration forces and moments. Static calibration data, found to produce the most reliable results, is presented for three degrees of freedom at 0, 15, and -10 deg angle of attack. Theoretical calculations are hampered by the inability to represent iron-cored electromagnets. Dynamic calibrations, despite being quicker and easier to perform, are not as accurate as static calibrations. Data for dynamic calibrations at 0 and 15 deg is compared with the relevant static data acquired. Distortion of oscillation traces is cited as a major source of error in dynamic calibrations.
Vilmercati, Paolo; Fedorov, Alexei; Bondino, Federica; Offi, Francesco; Panaccione, Giancarlo; Lacovig, Paolo; Simonelli, Laura; McGuire, Michael A.; Sefat, Athena S. M.; Mandrus, David; Sales, Brian C.; Egami, Takeshi; Ku, Wei; Mannella, Norman
2012-06-15
A direct and element-specific measurement of the local Fe spin moment has been provided by analyzing the Fe 3s core level photoemission spectra in the parent and optimally doped CeFeAsO₁₋_{x}F_{x} (x = 0, 0.11) and Sr(Fe₁₋_{x}Co_{x})2As2 (x = 0, 0.10) pnictides. The rapid time scales of the photoemission process allowed the detection of large local spin moments fluctuating on a 10⁻¹⁵ s time scale in the paramagnetic, antiferromagnetic, and superconducting phases, indicative of the occurrence of ubiquitous strong Hund's magnetic correlations. The magnitude of the spin moment is found to vary significantly among different families, 1.3μ_{B} in CeFeAsO and 2.1μB in SrFe₂As₂. Surprisingly, the spin moment is found to decrease considerably in the optimally doped samples, 0.9μ_{B} in CeFeAsO₀.₈₉F₀.₁₁ and 1.3μ_{B} in Sr(Fe₀.₉Co₀.₁)₂As₂. The strong variation of the spin moment against doping and material type indicates that the spin moments and the motion of itinerant electrons are influenced reciprocally in a self-consistent fashion, reflecting the strong competition between the antiferromagnetic superexchange interaction among the spin moments and the kinetic energy gain of the itinerant electrons in the presence of a strong Hund's coupling. By describing the evolution of the magnetic correlations concomitant with the appearance of superconductivity, these results constitute a fundamental step toward attaining a correct description of the microscopic mechanisms shaping the electronic properties in the pnictides, including magnetism and high-temperature superconductivity.
Prospects for measuring the moment of inertia of pulsar J0737-3039A
NASA Astrophysics Data System (ADS)
Iorio, Lorenzo
2009-01-01
Here we consider the possibility-envisaged by many authors as feasible in the near future-of measuring at 10% or better the moment of inertia I of the pulsar J0737-3039A via the gravitomagnetic spin-orbit periastron precession (analogous to the Lense-Thirring pericentre precession in the case of a test-particle orbiting a central spinning mass). Such a gravitomagnetic effect is expected to be of the order of 10-4deg yr and the present-day precision in measuring the periastron precession of J0737-3039A via pulsar timing is 6.8×10-4deg yr. However the systematic uncertainty in the much larger first-order post-Newtonian (1PN) gravitoelectric precession (analogous to the Einstein Mercury's perihelion precession in the weak-field and slow-motion approximation), which should be subtracted from the measured one in order to pick up the gravitomagnetic rate, is of primary importance. Indeed, by determining the sum of the masses by means of the third Kepler law, such a bias amounts to 0.03165 deg yr -1, according to the current level of accuracy in knowing the parameters of the J0737-3039 system. The major sources of uncertainty are the Keplerian projected semimajor axis x of the component B and the post-Keplerian parameter s, identified with sini; their knowledge should be improved by three orders of magnitude at least; the bias due to the Keplerian projected semimajor axis x of the component A amounts to ≈10% today. The present-day level of accuracy in the eccentricity e would affect the investigated measurement at a percent level, while the impact of the orbital period P is completely negligible. If, instead, the sum of the masses is measured by means of the post-Keplerian parameters r and s, it turns out that r should be measured five orders of magnitude better than now: according to the present-day level of accuracy, the total uncertainty in the 1PN periastron rate is, in this case, 2.11819 deg yr -1. In conclusion, the prospect of measuring the moment of inertia of
Third Elementary Dipole Moment: Toroidal
NASA Astrophysics Data System (ADS)
Cordrey, Vincent; Eshete, Amanuel; Majewski, Walerian
2015-04-01
In this paper we study the generally unknown characteristics of toroids, magnets without magnetic poles. Toroids have never seemed interesting enough to be studied for their physical features in labs due to the fact that they have no magnetic fields on the outside, but rather a very strong magnetic field trapped inside. Toroidal solenoids or magnets (rings magnetized circumferentially) interact with the external magnetic field only through its curl, which can be created either by an electric current, or by a time-dependent electric flux. We confirmed a theoretical prediction, that a toroid would not interact with the curl-less magnetic field of a current-carrying wire running outside of the torus's hole. We used our toroids as magnetic curlmeters, measuring the torque on the toroid, when the current-carrying wire runs through the toroid. From this torque we found the toroidal dipole moment. We are experimenting on detecting the escape of the inner magnetic field of the toroid outside of it, when magnetic toroid rotates or when electric toroid is driven by AC voltage. We also will discuss toroidal (or anapole) moments of fundamental particles, nuclei and atoms, and toroids' applications in metamaterials.
NASA Technical Reports Server (NTRS)
Goodyer, M. J.; Britcher, C. P.
1983-01-01
The results of experimental demonstrations of a superconducting solenoid model core in the Southampton University Magnetic Suspension and Balance System are detailed. Technology and techniques relevant to large-scale wind tunnel MSBSs comprise the long term goals. The magnetic moment of solenoids, difficulties peculiar to superconducting solenoid cores, lift force and pitching moment, dynamic lift calibration, and helium boil-off measurements are discussed.
Laser trapping of Ra-225 and Ra-226 and progress towards an electric dipole moment measurement
NASA Astrophysics Data System (ADS)
Guest, J. R.; Scielzo, N. D.; Ahmad, I.; Bailey, K.; Greene, J. P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Potterveld, D. H.
2006-10-01
Permanent electric dipole moments (EDMs) in atoms or molecules are signatures of Time (T)-and Parity (P)-violation and represent an important window onto physics beyond the Standard Model. We are developing a next generation EDM search around laser-cooled and trapped Ra-225 (t1/2 = 15 d). Due to octupole deformation of the nucleus, Ra-225 is predicted to be two to three orders of magnitude more sensitive to T-violating interactions than Hg-199, which currently sets the most stringent limits in the nuclear sector. We will discuss our progress, including the successful laser cooling and trapping of Ra-225 and Ra-226 atoms. We have demonstrated transverse cooling, Zeeman slowing, and capture of Ra-225 and Ra-226 atoms in a magneto-optical trap (MOT). By driving a second atomic transition, we have extended the lifetime of the trap from milliseconds to seconds and performed necessary spectroscopic measurements.
Interface magnetic moments enhancement of FePt-L10/MgO(001): An ab initio study
NASA Astrophysics Data System (ADS)
Cuadrado, R.; Chantrell, R. W.
2014-03-01
The interface between FePt-L10 and MgO(001) alloys has been studied using density-functional calculations. Because the stacking of the face-centered tetragonal L10 phase is formed by alternating Fe and Pt planes, both the Fe- and Pt-terminated contact layers were studied. Furthermore, due to the large mismatch between the in-plane lattice constants of both systems, we have chosen some common a values for both alloys in order to explore in detail the adsorption energy, the electronic structure, and the interface magnetism. The adsorption energy has been calculated by subtracting the energy of clean FePt and MgO alloys from the total energy. The preferred adsorbed geometric sites for Fe/Pt atoms are when they lie on top of the O species, having a smaller adsorption energy for the remaining positions. We found that expanding the MgO lattice enhances the magnetic moment of the Fe species but the Pt moments remain almost constant.
Magnetic diode for measurement of magnetic-field strength
Fedotov, S.I.; Zalkind, V.M.
1988-02-01
The accuracy of fabrication and assembly of the elements of the magnetic systems of thermonuclear installations of the stellarator type is checked by study of the topography of the confining magnetic field and is determined by the space resolution and accuracy of the measuring apparatus. A magnetometer with a galvanomagnetic sensor is described that is used to adjust the magnetic system of the Uragan-3 stellarator. The magnetometer measure magnetic-field induction in the range of 6 x 10/sup -7/-10/sup -2/ T with high space resolution.
Manal, Kurt; Cowder, Justin D; Buchanan, Thomas S
2013-01-01
The Achilles tendon (AT) moment arm is an important biomechanical parameter most commonly estimated using one of two methods: (A) center of rotation and (B) tendon excursion. Conflicting findings regarding magnitude and whether it changes with contraction intensity have been reported when using these methods. In this study, we present an alternate method of measuring the AT moment arm by combining ultrasound and video-based motion capture. Moment arms for 10 healthy male subjects were measured at five different joint angles in 10° increments ranging from 20° of dorsiflexion (DF) to 20° of plantar flexion (PF). Moment arms were measured at rest and also during maximum voluntary contraction (MVC). For both conditions, the AT moment arm increased in magnitude as the ankle moved from DF to PF. In 20° of DF, the moment arm at rest averaged 34.6 ± 1.8 mm and increased to a maximum value of 36.9 ± 1.9 mm when plantar flexed to 10°. Moment arms during MVC ranged from 35.7 ± 1.8 mm to 38.1 ± 2.6 mm. The moment arms we obtained were much more consistent with literature values derived using ultrasound and tendon excursion compared to center of rotation or in vitro methods. This is noteworthy as the hybrid method is easy to implement and as it is less costly and timing consuming than other methods, including tendon excursion, it is well suited for large-scale studies involving many subjects. PMID:24400141
Fiedler, Goeran; Slavens, Brooke; Smith, Roger O; Briggs, Douglas; Hafner, Brian J
2014-06-01
Prosthesis-integrated sensors are appealing for use in clinical settings where gait analysis equipment is unavailable, but accurate knowledge of patients' performance is desired. Data obtained from load cells (inferring joint moments) may aid clinicians in the prescription, alignment, and gait rehabilitation of persons with limb loss. The purpose of this study was to assess the accuracy of prosthesis-integrated load cells for routine use in clinical practice. Level ground walking of persons with transtibial amputation was concurrently measured with a commercially available prosthesis-integrated load cell, a 10-camera motion analysis system, and piezoelectric force plates. Ankle and knee flexion/extension moments were derived and measurement methods were compared via correlation analysis. Pearson correlation coefficients ranged from 0.661 for ankle pronation/supination moments to 0.915 for ankle flexion/extension moments (P < .001). Root mean squared errors between measurement methods were in the magnitude of 10% of the measured range and were explainable. Differences in results depicted differences between systems in definition and computation of measurement variables. They may not limit clinical use of the load cell, but should be considered when data are compared directly to conventional gait analysis data. Construct validity of the load cell (ie, ability to measure joint moments in-situ) is supported by the study results.
Fiedler, Goeran; Slavens, Brooke; Smith, Roger O.; Briggs, Douglas; Hafner, Brian J.
2014-01-01
Prosthesis-integrated sensors are appealing for use in clinical settings where gait analysis equipment is unavailable, but accurate knowledge of patients’ performance is desired. Data obtained from load cells (inferring joint moments) may aid clinicians in the prescription, alignment and gait rehabilitation of persons with limb loss. Purpose of this study was to assess the accuracy of prosthesis-integrated load cells for routine use in clinical practice. Level ground walking of persons with transtibial amputation was concurrently measured with a commercially-available prosthesis-integrated load cell, a 10-camera motion analysis system, and piezoelectric force plates. Ankle and knee flexion/extension moments were derived and measurement methods were compared via correlation analysis. Pearson correlation coefficients ranged from 0.661 for ankle pronation/supination moments to 0.915 for ankle flexion/extension moments (p<0.001). Root mean squared errors between measurement methods were in the magnitude of 10% of the measured range and were explainable. Differences in results depicted differences between systems in definition and computation of measurement variables. They may not limit clinical use of the load cell, but should be considered when data are compared directly to conventional gait analysis data. Construct validity of the load cell (i.e., ability to measure joint moments in-situ) is supported by the study results. PMID:24603673
Magnetic Moments in the Past: developing archaeomagnetic dating in the UK
NASA Astrophysics Data System (ADS)
Outram, Zoe; Batt, Catherine M.; Linford, Paul
2010-05-01
magnetic measurements. The information collated within the database will also be added to the global databases, such as MaGIC, contributing the improvement of the global models of the geomagnetic field. This project demonstrates the benefits that the presentation of clear, accessible information and increased communication with archaeologists can have on the study of the geomagnetic field. It is also hoped that similar approaches will beintroduced on a wider geographical scale in the future.
MICE Spectrometer Solenoid Magnetic Field Measurements
Leonova, M.
2013-09-01
The Muon Ionization Cooling Experiment (MICE) is designed to demonstrate ionization cooling in a muon beam. Its goal is to measure a 10% change in transverse emittance of a muon beam going through a prototype Neutrino Factory cooling channel section with an absolute measurement accuracy of 0.1%. To measure emittances, MICE uses two solenoidal spectrometers, with Solenoid magnets designed to have 4 T fields, uniform at 3 per mil level in the tracking volumes. Magnetic field measurements of the Spectrometer Solenoid magnet SS2, and analysis of coil parameters for input into magnet models will be discussed.
Quadrupole moment measurements for strongly deformed bands in {sup 171,172}Hf
Mukhopadhyay, S.; Ma, W. C.; Ijaz, Q. A.; Marsh, J.; Yadav, R. B.; Janssens, R. V. F.; Carpenter, M. P.; Khoo, T. L.; Lauritsen, T.; Zhu, S.; Chiara, C. J.; Chowdhury, P.; Hota, S. S.; Lakshmi, S.; Cullen, D. M.; Hagemann, G. B.; Hartley, D. J.; Kondev, F. G.; Riedinger, L. L.; Toh, Y.
2011-04-15
A lifetime experiment, using the Doppler-shift attenuation method, has been performed at Gammasphere to measure the transition quadrupole moments Q{sub t} of strongly deformed bands in {sup 171}Hf and {sup 172}Hf. The measured value of Q{sub t} {approx} 9.5 e b for the band labeled ED in {sup 171}Hf strongly supports the recent suggestion that this sequence and several structures with similar properties in neighboring Hf isotopes are associated with a near-prolate shape with a deformation enhanced relative to that of normal deformed structures. The measured values of Q{sub t} {approx} 14 e b for the bands labeled SD1 and SD3 in {sup 172}Hf confirm that these sequences are associated with a prolate superdeformed shape, a property inferred in earlier work from other measured characteristics of the bands. Similar bands in {sup 173-175}Hf are also likely to be associated with superdeformed shapes. The observations are in contrast to predictions of cranking calculations performed with the ultimate cranker code.
An information complexity index for probability measures on ℝ with all moments
NASA Astrophysics Data System (ADS)
Accardi, Luigi; Barhoumi, Abdessatar; Rhaima, Mohamed
2016-08-01
We prove that, each probability meassure on ℝ, with all moments, is canonically associated with (i) a ∗-Lie algebra; (ii) a complexity index labeled by pairs of natural integers. The measures with complexity index (0,K) consist of two disjoint classes: that of all measures with finite support and the semi-circle-arcsine class (the discussion in Sec. 4.1 motivates this name). The class C(μ) = (0, 0) coincides with the δ-measures in the finite support case and includes the semi-circle laws in the infinite support case. In the infinite support case, the class C(μ) = (0, 1) includes the arcsine laws, and the class C(μ) = (0, 2) appeared in central limit theorems of quantum random walks in the sense of Konno. The classes C(μ) = (0,K), with K ≥ 3, do not seem to be present in the literature. The class (1, 0) includes the Gaussian and Poisson measures and the associated ∗-Lie algebra is the Heisenberg algebra. The class (2, 0) includes the non-standard (i.e. neither Gaussian nor Poisson) Meixner distributions and the associated ∗-Lie algebra is a central extension of sl(2, ℝ). Starting from n = 3, the ∗-Lie algebra associated to the class (n, 0) is infinite dimensional and the corresponding classes include the higher powers of the standard Gaussian.
Roda, Richard D; Wilson, Janie L Astephen; Wilson, David A J; Richardson, Glen; Dunbar, Michael J
2012-06-01
Computer-assisted surgery can be used to measure 3-dimensional knee function during arthroplasty surgery; however, it is unknown if the movement of the knee measured during surgery is related to the in vitro, dynamic state of the knee joint, specifically the knee adduction moment during gait, which has been related to implant migration. The purpose of this study was to determine if the preoperative adduction moment is correlated with the knee abduction/adduction angle measured intraoperatively. A statistically significant correlation was found between the mean (r(2) = 0.59; P = .001) and peak (r(2) = 0.53; P = .003) preoperative knee adduction moment and the mean abduction/adduction angle measured intraoperatively. The association found in this study suggests the potential for incorporating functional information that relates to surgical outcome into surgical decision making using computer-assisted surgery.
Meinert, Markus; Schmalhorst, Jan-Michael; Klewe, Christoph; Reiss, Guenter; Arenholz, Elke; Boehnert, Tim; Nielsch, Kornelius
2011-10-01
Epitaxial thin films of the half-metallic X{sub a} compound Mn{sub 2}CoGa (Hg{sub 2}CuTi prototype) were prepared by dc magnetron co-sputtering with different heat treatments on MgO (001) substrates. High-quality films with a bulk magnetization of 1.95(5) {mu}{sub B} per unit cell were obtained. The L{sub 3,2} x-ray magnetic circular dichroism spectra agree with calculations based on density functional theory (DFT) and reveal the antiparallel alignment of the two inequivalent Mn moments. X-ray magnetic linear dichroism, in good agreement with theory as well, allows us to distinguish between itinerant and local Mn moments. Based on noncollinear spin DFT, it is shown that one of the two Mn moments has local character, whereas the other Mn moment and the Co moment are itinerant.
Flatcoil systems for measurements of Fermilab magnets
Glass, H.D.; Brown, B.C.; DiMarco, J.
1995-06-01
A flux measurement system has been developed for measuring the integrated strength and relative shape of the magnetic field of Fermilab Main Injector dipoles. Improved field shape measurements have been obtained by constructing coil geometries which reduce the flux contribution from unwanted field derivatives. A bucking coil scheme employing reference coils in both the test magnet and a reference magnet reduce the sensitivity to power supply fluctuations. Design strategies for various measurement requirements are described, along with the details of implementing an assembly to measure curved 6 m and 4 m dipoles. Some representative results and comparison with redundant measurement systems are presented.
Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO.
Baumann, S; Donati, F; Stepanow, S; Rusponi, S; Paul, W; Gangopadhyay, S; Rau, I G; Pacchioni, G E; Gragnaniello, L; Pivetta, M; Dreiser, J; Piamonteze, C; Lutz, C P; Macfarlane, R M; Jones, B A; Gambardella, P; Heinrich, A J; Brune, H
2015-12-01
We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0±0.3 meV/atom. This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.
Automatic magnetic flux measurement of micro plastic-magnetic rotors
NASA Astrophysics Data System (ADS)
Wang, Qingdong; Lin, Mingxing; Song, Aiwei
2015-07-01
Micro plastic-magnetic rotors of various sizes and shapes are widely used in industry, their magnetic flux measurement is one of the most important links in the production process, and therefore some technologies should be adopted to improve the measurement precision and efficiency. In this paper, the automatic measurement principle of micro plastic-magnetic rotors is proposed and the integration time constant and the integrator drift’s suppression and compensation in the measurement circuit are analyzed. Two other factors influencing the measurement precision are also analyzed, including the relative angles between the rotor magnetic poles and the measurement coil, and the starting point of the rotors in the coil where the measurement begins. An instrument is designed to measure the magnetic flux of the rotors. Measurement results show that the measurement error is within ±1%, which meets the basic requirements in industry application, and the measurement efficiency is increased by 10 times, which can cut down labor cost and management cost when compared with manual measurement.
First Measurement of the Permanent Electric Dipole Moment of Radium-225
NASA Astrophysics Data System (ADS)
Singh, Jaideep T.; Bailey, K. G.; Bishof, M. N.; Dietrich, M. R.; Greene, J. P.; Holt, R. J.; Kalita, M. R.; Korsch, W.; Lemke, N. D.; Lu, Z.-T.; Mueller, P.; O'Connor, T. P.; Parker, R. H.
2015-04-01
Electric dipole moments (EDMs) are signatures of time-reversal (T), parity (P),& charge-parity (CP) violation. CP -violation beyond the Standard Model is generally believed to be required to explain the observed prevalence of matter over antimatter in the universe. Radium-225 (τ1 / 2 = 14 . 7 d, I = 1 / 2) is mostly sensitive to T- and P-violating interactions originating within the nucleus. The best limits on these types of exotic interactions are derived from the atomic EDM limit for Mercury-199. Because of its unusual nuclear structure (octupole deformation), Ra-225 is expected to have a physics sensitivity that is a few hundred to a few thousand times higher than Hg-199. Laser cooling & trapping techniques are performed to collect & transport the cold Ra atoms into the measurement region. An EDM measurement is then performed by searching for a linear electric field dependent shift in the nuclear spin precession frequency of Ra-225. We will report on the first measurement of the atomic EDM of Ra-225 as well as plans for future improvements. This work is supported by U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract DE-AC02-06CH11357.
Thermochemical Beam Source of ThO for Measuring the Electric Dipole Moment of the Electron
NASA Astrophysics Data System (ADS)
Petrik, Elizabeth; Baron, Jacob; Hutzler, Nick; Lasner, Zack; O'Leary, Brendon; Panda, Cristian; West, Adam; Wilburn, Grey; Demille, David; Gabrielse, Gerald; Doyle, John
2016-05-01
The observation of an electron electric dipole moment (eEDM) would reveal new sources of time-reversal symmetry violation, potentially shedding light on the excess of matter over antimatter in the universe. Certain heavy polar molecules have a large interaction between the nuclear electric field and the eEDM that can be interrogated in the lab, making them ideal for eEDM searches. This molecular feature allowed our measurement with thorium monoxide (ThO) to set the most stringent upper limit on the eEDM to date. Producing enough such molecules in the gas phase to perform a precision measurement is challenging because of their reactivity and low vapor pressure. Thus, a cryo buffer gas beam source yielding a high flux (1013/s) of cold (4 K), slow (170 m/s) ThO via laser ablation of ThO2 was critical to our success. We now report on progress towards an improved beam source, which relies on favorable thorium-oxygen chemistry to produce gas-phase ThO via laser heating of a mixture of ThO2 and Th. This new source has an average beam flux > 5 times larger than in and will contribute to a future eEDM measurement with greatly improved statistics. Funded by the NSF.
NASA Astrophysics Data System (ADS)
Zhou, Yan; Gresh, Daniel; Cairncross, William; Grau, Matt; Ng, Kia Boon; Ni, Yiqi; Cornell, Eric; Ye, Jun
2016-05-01
Based on our latest measurements of the electron's electric dipole moment (eEDM) using trapped HfF+ ions, after 100 hours of data collection, the statistical error still dominates in our overall uncertainty budget. Overcoming the bottleneck of limited statistical sensitivity can increase the precision of the eEDM measurement directly. Here, we present the progress of three ongoing experiments: (1) applying STImulated Raman Adiabatic Passage (STIRAP) with rotating linear polarization for increased coherent population transfer from the ground X1Σ+ state to the eEDM-sensitive 3Δ1 state; (2) implementing a new ion-counting detector toward shot-noise limited sensitivity with significant suppression technical noise; (3) exploring the possibility of using the ground 3Δ1 state of ThF+ ions to realize a larger effective electric field and a longer coherence time. These experiments provide a route towards an order of magnitude increase in statistical sensitivity in the second generation of measurements.
Measurement of hinge moments and model deformations in wind tunnels by means of Moire interferometry
NASA Astrophysics Data System (ADS)
Baumann, Peter H.; Butefisch, K. A.
1995-09-01
A nonintrusive Moire interferometry system has been designed to acquire the instantaneous deformation of models during wind tunnel testing. The resulting interferograms are evaluated without manual intervention using a technique based on the Fourier Transform. The deformation of a large- scale model wing (generic model of a transport aircraft with a full span of 3.40 m) has been measured in the 8 m X 6 m test section of the subsonic Deutsch-Niederlandischer-Windkanal (DNW). At 400 individual locations along the span, the bending and twist deformations of the wing have been measured with an average accuracy of +/- 0.1 mm and +/- 0.03 degree(s), respectively. In a second experiment, the bending angle of a flap of a hypersonic vehicle was measured in order to determine the hinge moment due to aerodynamic loads. The experiment was carried out in the transonic wind tunnel Gottingen (TWG). To obtain data for comparison, the hinges were equipped with strain gauges. The results of both techniques show a maximum deviation of 0.02 degree(s).
The magnetic moment enigma in Fe-based high temperature superconductors.
Mannella, Norman
2014-11-26
The determination of the most appropriate starting point for the theoretical description of Fe-based materials hosting high-temperature superconductivity remains among the most important unsolved problem in this relatively new field. Most of the work to date has focused on the pnictides, with LaFeAsO, BaFe(2)As(2) and LiFeAs being representative parent compounds of three families known as 1111, 122 and 111, respectively. This topical review examines recent progress in this area, with particular emphasis on the implication of experimental data which have provided evidence for the presence of electron itinerancy and the detection of local spin moments. In light of the results presented, the necessity of a theoretical framework contemplating the presence and the interplay between itinerant electrons and large spin moments is discussed. It is argued that the physics at the heart of the macroscopic properties of pnictides Fe-based high-temperature superconductors appears to be far more complex and interesting than initially predicted. PMID:25352180
Microscopic magnetic properties of an oxygen-doped Tb-Fe thin film by magnetic Compton scattering
Agui, Akane; Unno, Tomoya; Matsumoto, Sayaka; Suzuki, Kousuke; Sakurai, Hiroshi; Koizumi, Akihisa
2013-11-14
The magnetic Compton scattering of a Tb{sub 32}Fe{sub 55}O{sub 13} film was measured in order to investigate the microscopic magnetization processes (i.e., the spin moment, orbital moment, and element specific moments). The trend of the spin magnetic moment was the same as that of the total magnetic moment but opposite to the orbital magnetic moment. In the low magnetic field region, the magnetic moments were not perfectly aligned perpendicular to the film surface, and the perpendicular components were found to mainly arise from the magnetic moment of Tb. Oxygen atoms hinder long range magnetic interaction and hence also affect the magnetization process of the magnetic moments of Tb and Fe.
Porter, Frank C.
2015-04-29
The BABAR collaboration has an extensive program of studying hadronic cross sections in low-energy e^{+}e^{-} collisions, accessible via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment. These improvements are necessary for illuminating the current 3.6 sigma difference between the predicted and the experimental values. We have published results on a number of processes with two to six hadrons in the final state. We report here the results of recent studies with final states that constitute the main contribution to the hadronic cross section in the energy region between 1 and 3 GeV, as e^{+}e^{-} → K^{+}K^{-}, π^{+}π^{-}, and e^{+}e^{-} → 4 hadrons
Removing Overprints, and Measuring Their Magnetic Vectors Using Microwaves
NASA Astrophysics Data System (ADS)
Walton, D.; Bohnel, H.
2008-05-01
Microwaves are strongly absorbed by generating spin waves in magnetic particles. They are also absorbed in dielectrics, but this is usually much weaker. Apart from the uniform mode where all the spins rotate in phase spin waves cannot exist whose wavelength is greater than twice the dimension of the particle in the propagation direction. Thus, the spin wave levels are quantized. For small particles the level separation is very large, and this means that particles of a given size can only absorb microwaves over a narrow range of frequencies. Thus, it is possible to selectively demagnetize the contributions of grains of different sizes to the magnetic moment of the sample, thereby identifying the original remanence and any subsequent overprints. In particular it should be possible to measure the viscous contribution in ceramics, thereby providing an accurate dating method. Details of the required instrumentation will be discussed, and recent experimental results will be presented.
Magnetic field measurements in tokamak plasmas
Feldman, U.; Seely, J.F.; Sheeley,Jr., N.R.; Suckewer, S.; Title, A.M.
1984-11-01
The measurement of the poloidal magnetic field in a tokamak plasma from the Zeeman splitting and polarization of the magnetic dipole radiation from heavy ions is discussed. When viewed from a direction perpendicular to the toroidal field, the effect of the poloidal field on the circularly polarized radiation is detectable using a photoelectric polarimeter. The Zeeman splittings for a number of magnetic dipole transitions with wavelengths in the range 2300--9300 A are presented. An imaging polarimeter is proposed that can measure the poloidal magnetic field with space and time resolution.
NASA Astrophysics Data System (ADS)
Girdhar, Aarti; Dahiya, Harleen; Randhawa, Monika
2015-08-01
The magnetic moments of JP=3/2+ decuplet baryons have been calculated in the chiral constituent quark model (χ CQM ) with explicit results for the contribution coming from the valence quark polarizations, sea quark polarizations, and their orbital angular momentum. Since the JP=3/2+ decuplet baryons have short lifetimes, the experimental information about them is limited. The χ CQM has important implications for chiral symmetry breaking as well as SU(3) symmetry breaking since it works in the region between the QCD confinement scale and the chiral symmetry breaking scale. The predictions in the model not only give a satisfactory fit when compared with the experimental data but also show improvement over the other models. The effect of the confinement on quark masses has also been discussed in detail and the results of χ CQM are found to improve further with the inclusion of effective quark masses.
Ong, A.; Berengut, J. C.; Flambaum, V. V.
2010-07-15
In this paper we consider the contribution of the anomalous magnetic moments of protons and neutrons to the nuclear charge density. We show that the spin-orbit contribution to the mean-square charge radius, which has been neglected in recent nuclear calculations, can be important in light halonuclei. We estimate the size of the effect in helium, lithium, and beryllium nuclei. It is found that the spin-orbit contribution represents a approx2% correction to the charge density at the center of the {sup 7}Be nucleus. We derive a simple expression for the correction to the mean-square charge radius due to the spin-orbit term and find that in light halonuclei it may be larger than the Darwin-Foldy term and comparable to finite size corrections. A comparison of experimental and theoretical mean-square radii including the spin-orbit contribution is presented.
Pajcini, V.; Asher, S.A.
1999-12-01
The authors have examined electronic coupling between the two amide electronic transitions in a dipeptide and have found strong excitonic interactions in a case where the amide planes are almost perpendicular. The absorption and resonance Raman spectra of N-methylacetamide (NMA) and acetamide (AM) are compared to that of the dipeptide N-acetylglycinamide (NAGA), which is composed of linked primary and secondary amides. The authors measured the transition moment magnitudes of each of these species and also determined the orientation of the preresonance Raman tensor of NAGA in a single crystal. From these single-crystal tensor values, the NAGA diagonal Raman tensor orientations were calculated and compared to those expected for unperturbed primary and secondary amides oriented as in the NAGA crystal. Because the primary and secondary amide III vibrations are vibrationally uncoupled and nonoverlapping, their intensities can be used to determine the contributions to their resonance enhancement from the coupled NAGA electronic transitions. The Raman tensor major axes of the primary and secondary amide III and amide I vibrations do not lie in their corresponding amide planes, indicating excitonically coupled states which mix the primary and secondary amide transitions. These results are relevant to the understanding of amide coupling in peptides and proteins; the NAGA crystal conformation is similar to that of a type I {beta}-turn in peptides and proteins, with the amide planes nearly perpendicular to each other (dihedral angle 85{degree}).
Magnetic Field Response Measurement Acquisition System
NASA Technical Reports Server (NTRS)
Woodard, Stanley E.; Taylor, Bryant D.; Shams, Qamar A.; Fox, Robert L.
2005-01-01
A measurement acquisition method that alleviates many shortcomings of traditional measurement systems is presented in this paper. The shortcomings are a finite number of measurement channels, weight penalty associated with measurements, electrical arcing, wire degradations due to wear or chemical decay and the logistics needed to add new sensors. The key to this method is the use of sensors designed as passive inductor-capacitor circuits that produce magnetic field responses. The response attributes correspond to states of physical properties for which the sensors measure. A radio frequency antenna produces a time-varying magnetic field used to power the sensor and receive the magnetic field response of the sensor. An interrogation system for discerning changes in the sensor response is presented herein. Multiple sensors can be interrogated using this method. The method eliminates the need for a data acquisition channel dedicated to each sensor. Methods of developing magnetic field response sensors and the influence of key parameters on measurement acquisition are discussed.
Materials with low DC magnetic susceptibility for sensitive magnetic measurements
NASA Astrophysics Data System (ADS)
Khatiwada, R.; Dennis, L.; Kendrick, R.; Khosravi, M.; Peters, M.; Smith, E.; Snow, W. M.
2016-02-01
Materials with very low DC magnetic susceptibility have many scientific applications. To our knowledge however, relatively little research has been conducted with the goal to produce a totally nonmagnetic material. This phrase in our case means after spatially averaging over macroscopic volumes, it possesses an average zero DC magnetic susceptibility. We report measurements of the DC magnetic susceptibility of three different types of nonmagnetic materials at room temperature: (I) solutions of paramagnetic salts and diamagnetic liquids, (II) liquid gallium-indium alloys and (III) pressed powder mixtures of tungsten and bismuth. The lowest measured magnetic susceptibility among these candidate materials is in the order of 10-9 cgs volume susceptibility units, about two orders of magnitude smaller than distilled water. In all cases, the measured concentration dependence of the magnetic susceptibility is consistent with that expected for the weighted sum of the susceptibilities of the separate components within experimental error. These results verify the well-known Wiedemann additivity law for the magnetic susceptibility of inert mixtures of materials and thereby realize the ability to produce materials with small but tunable magnetic susceptibility. For our particular scientific application, we are also looking for materials with the largest possible number of neutrons and protons per unit volume. The gallium-indium alloys fabricated and measured in this work possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature liquid, and the tungsten-bismuth pressed powder mixtures possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature solid. This ratio is a figure of merit for a certain class of precision experiments that search for possible exotic spin-dependent forces of Nature.
Yang, Xiaoyu Chen, Lifan; Han, Hongmei; Fu, Lianfeng; Sun, Ming; Liu, Feng; Zhang, Jinqiu
2014-05-07
The impact of the fluorine-based reactive ion etch (RIE) process on the structural, electrical, and magnetic properties of NiFe and CoNiFe-plated materials was investigated. Several techniques, including X-ray fluorescence, 4-point-probe, BH looper, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS), were utilized to characterize both bulk film properties such as thickness, average composition, Rs, ρ, Bs, Ms, and surface magnetic “dead” layers' properties such as thickness and element concentration. Experimental data showed that the majority of Rs and Bs changes of these bulk films were due to thickness reduction during exposure to the RIE process. ρ and Ms change after taking thickness reduction into account were negligible. The composition of the bulk films, which were not sensitive to surface magnetic dead layers with nano-meter scale, showed minimum change as well. It was found by TEM and EELS analysis that although both before and after RIE there were magnetic dead layers on the top surface of these materials, the thickness and element concentration of the layers were quite different. Prior to RIE, dead layer was actually native oxidation layers (about 2 nm thick), while after RIE dead layer consisted of two sub-layers that were about 6 nm thick in total. Sub-layer on the top was native oxidation layer, while the bottom layer was RIE “damaged” layer with very high fluorine concentration. Two in-situ RIE approaches were also proposed and tested to remove such damaged sub-layers.
NASA Astrophysics Data System (ADS)
Kawamura, Hirokazu; Ando, S.; Aoki, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Uchiyama, A.; Aoki, T.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Imai, K.; Murakami, T.; Nataraj, H. S.; Sato, T.; Shimizu, Y.; Wakasa, T.; Yoshida, H. P.; Sakemi, Y.
An experiment to search for the electron electric dipole moment using francium is planned to test the new physics beyond the standard model. The optical lattice trapping of the francium that is produced through the nuclear fusion reaction at high heat may allow for a precise measurement of the electric dipole moment. The magneto-optical trapping of the francium is required as a precooling treatment. The factory of laser-cooled francium atoms has been developed for the magneto-optical trap. Currently, the apparatus that is able to trap a few atoms is constructed to identify the resonant frequency of francium.
The permanent electric dipole moments and magnetic g(e)-factors of praseodymium monoxide (PrO).
Wang, Hailing; Linton, Colan; Ma, Tongmei; Steimle, Timothy C
2009-11-26
The R(4.5) and P(6.5) branch features of the XX (0, 0) band of praseodymium monoxide (PrO) have been studied at a resolution of approximately 50 MHz field free and in the presence of static electric and magnetic fields. The permanent electric dipole moments, mu(el), of 3.01(6) D and 4.72(5) D for the X(2) (Omega = 4.5) and [18.1] (Omega = 5.5) states, respectively, were determined from the analysis of the Stark spectra. The magnetic g(e)-factors of 4.48(8) and 5.73(6) for the X(2) (Omega = 4.5) and [18.1] (Omega = 5.5) states, respectively, were determined from the analysis of the Zeeman spectra. The g(e)-factors are compared with those computed using wave functions predicted from ligand field theory and ab initio calculations. The mu(el) value for the X(2) (Omega = 4.5) state is compared to ab initio and density functional predicted values and with the experimental values of other lanthanide monoxides.
Cui, Peiling; Zhang, Huijuan; Yan, Ning; Fang, Jiancheng
2012-01-01
Integrating the advantage of magnetic bearings with a double gimble control moment gyroscope (DGCMG), a magnetically suspended DGCMG (MSDGCMG) is an ideal actuator in high-precision, long life, and rapid maneuver attitude control systems. The work presented here mainly focuses on performance testing of a MSDGCMG independently developed by Beihang University, based on the single axis air bearing table. In this paper, taking into sufficient consideration to the moving-gimbal effects and the response bandwidth limit of the gimbal, a special MSDGCMG steering law is proposed subject to the limits of gimbal angle rate and angle acceleration. Finally, multiple experiments are carried out, with different MSDGCMG angular momenta as well as different desired attitude angles. The experimental results indicate that the MSDGCMG has a good gimbal angle rate and output torque tracking capabilities, and that the attitude stability with MSDGCMG as actuator is superior to 10−3°/s. The MSDGCMG performance testing in this paper, carried out under moving-base condition, will offer a technique base for the future research and application of MSDGCMGs. PMID:23012536
Bonding, moment formation, and magnetic interactions in Ca14MnBi11 and Ba14MnBi11
NASA Astrophysics Data System (ADS)
Sánchez-Portal, D.; Martin, Richard M.; Kauzlarich, S. M.; Pickett, W. E.
2002-04-01
``14-1-11'' phase compounds, based on magnetic Mn ions and typified by Ca14MnBi11 and Ba14MnBi11, show an unusual magnetic behavior, but the large number (104) of atoms in the primitive cell has precluded any previous full electronic structure study. Using an efficient, local-orbital-based method within the local-spin-density approximation to study the electronic structure, we find a gap between a bonding valence-band complex and an antibonding conduction-band continuum. The bonding bands lack one electron per formula unit of being filled, making them low carrier density p-type metals. The hole resides in the MnBi4 tetrahedral unit, and partially compensates for the high-spin d5 Mn moment, leaving a net spin near 4μB that is consistent with experiment. These manganites are composed of two disjoint but interpenetrating ``jungle gym'' networks of spin-4/2 MnBi9-4 units with ferromagnetic interactions within the same network, and weaker couplings between the networks whose sign and magnitude is sensitive to materials parameters. Ca14MnBi11 is calculated to be ferromagnetic as observed, while for Ba14MnBi11 (which is antiferromagnetic) the ferromagnetic and antiferromagnetic states are calculated to be essentially degenerate. The band structure of the ferromagnetic states is very close to half metallic.
An online database of nuclear electromagnetic moments
NASA Astrophysics Data System (ADS)
Mertzimekis, T. J.; Stamou, K.; Psaltis, A.
2016-01-01
Measurements of nuclear magnetic dipole and electric quadrupole moments are considered quite important for the understanding of nuclear structure both near and far from the valley of stability. The recent advent of radioactive beams has resulted in a plethora of new, continuously flowing, experimental data on nuclear structure - including nuclear moments - which hinders the information management. A new, dedicated, public and user friendly online database
Extensive Measurements of Vibration-Induced Permanent Electric Dipole Moments of Methane
NASA Astrophysics Data System (ADS)
Okuda, Shoko; Sasada, Hiroyuki
2016-06-01
A methane molecule (CH_4) has a permanent electric dipole moment (PEDM) in the excited state of the triply-degenerate vibrational modes. The rotational dependence of the PEDM was reported in the 2νb{3} band. However, in the νb{3} band, it was only determined on the P(7) E transition which fortunately lies in the tunable range of a 3.4 μm He-Ne laser. We have developed a mid-infrared broadband sub-Doppler resolution spectrometer consisting of a difference-frequency-generation source and an optical frequency comb linked to International Atomic Time. This spectrometer enables us to measure the Stark effects of 20 transitions in the νb{3} band of methane from 87.7 to 92.8 THz (2927˜3095 wn). The observed linewidth is 0.5 MHz, and the frequency scale is absolutely calibrated. The figure depicts the Stark modulation spectrum of the P(4) E transition. The applied DC electric field was 3.5 kV/cm. We determined Stark coefficients with a relative uncertainty of 1 %. Our goal is to reveal the rotational dependence of the PEDM. For this end, we yield molecular constants which reproduce the transition frequencies by a least-square method and determine the mixing of the wave functions. M. Mizushima and P. Venkateswarlu, J. Chem. Phys. 21, 705 (1953) K. Uehara, K. Sakurai and K. Shimoda, J. Phys. Soc. Jpn. 26, 1018 (1969) H. Sasada, K. Suzumura and C. Ishibashi, J. Chem. Phys. 105, 9027 (1996)
Zhang Jinqiu; Liu Feng; Chen Lifan; Miloslavsky, Lena
2010-05-15
Effect of reactive gas (oxygen/chlorine/fluorine) etching on NiFe magnetic properties was investigated. Experimental data showed 40% magnetic property degradation for F-containing gas etching, 10% degradation for O-containing gas etching, and 5% degradation for Cl-containing gas etching processes. X-ray diffraction analysis indicated that the crystallographic orientation remained the same upon the reactive gas etching, which is due to the low ion energy in plasma etching process as opposed to ion milling process with high input energy. It is proposed that the reported magnetic property degradation was mainly caused by the nonmagnetic dead layer formation, rather than the changes in the crystallographic orientation. The dead layer was determined by the NiFe thickness dependence of remnant magnetic flux variations between pre-etched and postetched samples. The dead layer remained nearly constant for O-containing gas etching process with increasing plasma processing time. The nonmagnetic dead layer of {approx}40-50 A formed in O-containing etching gas was observed in transmission electron microscopy cross-sectional image and was in very good agreement with the calculated value based on magnetic flux measurements. Combined magnetic and physical characterizations suggest that the dead layer thickness saturates at the initial stage of the plasma etching and magnetic property remained unchanged with increasing etching duration upon formation of the dead layer.
Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma
NASA Astrophysics Data System (ADS)
Yousefi, Razieh; Davis, Allen B.; Carmona-Reyes, Jorge; Matthews, Lorin S.; Hyde, Truell W.
2014-09-01
Understanding the agglomeration of dust particles in complex plasmas requires knowledge of basic properties such as the net electrostatic charge and dipole moment of the dust. In this study, dust aggregates are formed from gold-coated mono-disperse spherical melamine-formaldehyde monomers in a radiofrequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining three-dimensional structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, as well as the external electric field, to be determined. It is shown that the experimental results support the predicted values from computer models for aggregates in these environments.
Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma
NASA Astrophysics Data System (ADS)
Yousefi, Raziyeh; Davis, Allen; Carmona-Reyes, Jorge; Matthews, Lorin; Hyde, Truell
2014-10-01
Understanding the behavior of dust particles in a complex plasma requires a knowledge of the basic properties such as the net electrostatic charge and dipole moment of the dust as well as the local electrostatic fields. In this study, dust aggregates are formed from gold coated monodisperse spherical melamine-formaldehyde monomers in a radio-frequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining 3D structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, and local electrostatic fields to be determined from the behavior of particles. It is shown that the experimental results agree with predicted values from computer models for aggregates in these environments. This work was supported by the National Science foundation under Grant No. 0847127.
NASA Astrophysics Data System (ADS)
Ye, Qiang
The search for the existence of a nonzero neutron electric dipole moment (nEDM) has the potential to reveal new sources of T and CP violation beyond the Standard Model and may have a significant impact on our understanding of the universe. A new experiment aiming at two orders of magnitude improvement (˜ 10--28 e·cm) over the current experimental upper limit has been proposed in the United States. In the experiment, the measurement cell will be made of dTPB-dPS coated acrylic and filled with superfluid 4He at ˜300-500 mK. The measurement of the neutron precession frequency will rely on the spin-dependence of the cross section of the nuclear reaction between polarized neutrons and 3He atoms: n⃗+H3 ⃗e → p + t + 764 keV. Polarized 3He will also be used as a comagnetometer based on the nuclear magnetic resonance technique. The 3He polarization needs to have sufficiently long relaxation time so that little polarization is lost during the measurement period in order to achieve the proposed sensitivity. Understanding the relaxation mechanism of 3He polarization in the measurement cell under the nEDM experimental conditions and maintaining 3He polarization is crucial for the experiment. With the presence of superfluid 4He, 3He relaxation time measurements in a dTPB-dPS coated cylindrical acrylic cell at the temperature of 1.9 K and ˜400 mK have been performed at the Triangle University Nuclear Laboratory (TUNL) on the campus of Duke University. The extracted depolarization probabilities of polarized 3He on the cell surface are on the order of (1 -- 2) x 10--7 at 1.9 K and ˜ 4.7 x 10--7 at ˜400 mK. The extrapolated relaxation time of polarized 3He in the nEDM cell geometry is ˜ 4870 seconds at ˜400 mK, which is sufficiently long for the nEDM experiment and further improvements are anticipated.
Hybrid of Quantum Phases for Induced Dipole Moments
NASA Astrophysics Data System (ADS)
Ma, Kai
2016-09-01
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.
NASA Astrophysics Data System (ADS)
Ze-Jin, Yang; Rong-Feng, Linghu; Qing-He, Gao; Heng-Na, Xiong; Zhi-Jun, Xu; Ling, Tang; Guo-Zhu, Jia; Yun-Dong, Guo
2016-09-01
The electronic structure and thermodynamical properties of Cr2TiAlC2 are studied by first principles under pressure. The obtained results observed that the ferromagnetic order is the most stable ground state and the magnetic moment will collapse at about 50 GPa. As a result, the lattice a axis becomes stiffer above about 420 GPa, ultimately presenting the same axial compressibility trends with those of nonmagnetic compounds Mo2TiAlC2 and hypothetical Cr2TiAlC2. The elastic constants and phonon dispersion curves demonstrate the structural stability during the disappearance of magnetic moment and occurrence of axial alternative compressibility. The density of states and energy band calculations confirmed the existence of magnetic moment of Cr2TiAlC2 at 0 GPa and disappearance at high pressures above 50 GPa. Evolutions of magnetic moment collapse with pressure are confirmed by a variety of properties. The obtained grüneisen parameter and thermal expansion coefficients show the maximum value among the known MAX phases, to date and to the author’s knowledge.
Ze-Jin, Yang; Rong-Feng, Linghu; Qing-He, Gao; Heng-Na, Xiong; Zhi-Jun, Xu; Ling, Tang; Guo-Zhu, Jia; Yun-Dong, Guo
2016-01-01
The electronic structure and thermodynamical properties of Cr2TiAlC2 are studied by first principles under pressure. The obtained results observed that the ferromagnetic order is the most stable ground state and the magnetic moment will collapse at about 50 GPa. As a result, the lattice a axis becomes stiffer above about 420 GPa, ultimately presenting the same axial compressibility trends with those of nonmagnetic compounds Mo2TiAlC2 and hypothetical Cr2TiAlC2. The elastic constants and phonon dispersion curves demonstrate the structural stability during the disappearance of magnetic moment and occurrence of axial alternative compressibility. The density of states and energy band calculations confirmed the existence of magnetic moment of Cr2TiAlC2 at 0 GPa and disappearance at high pressures above 50 GPa. Evolutions of magnetic moment collapse with pressure are confirmed by a variety of properties. The obtained grüneisen parameter and thermal expansion coefficients show the maximum value among the known MAX phases, to date and to the author’s knowledge. PMID:27666292
Electric Dipole Moments of Nitric Acid-Water Complexes Measured by Cluster Beam Deflection
Moro, Ramiro; Heinrich, Jonathon; Kresin, Vitaly V.
2009-12-03
Water clusters embedding a nitric acid molecule HNO{sub 3}(H{sub 2}O){sub n=1-10} are investigated via electrostatic deflection of a molecular beam. We observe large paraelectric susceptibilities that greatly exceed the electronic polarizability, revealing the contribution of permanent dipole moments. The moments derived from the data are also significantly higher than those of pure water clusters. An enhancement in the susceptibility for n = 5, 6 and a rise in cluster abundances setting in at n = 6 suggest that dissociation of the solvated acid molecule into ions takes place in this size range.
Measuring the interaction force between a high temperature superconductor and a permanent magnet
NASA Astrophysics Data System (ADS)
Valenzuela, S. O.; Jorge, G. A.; Rodríguez, E.
1999-11-01
Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give rise to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction, which represents a promising field with regard to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt-textured YBa2Cu3O7 superconductor immersed in liquid nitrogen. The simple design of the experiments allows a fast and easy implementation in the advanced physics laboratory with a minimum cost. Actual levitation and suspension demonstrations can be done simultaneously as a help to interpret magnetic force measurements.
Klose, Verena
2011-08-12
This thesis presents first measurements of moments of the hadronic n_{X}^{2} distribution measured in inclusive semileptonic decays of B mesons to final states containing a charm quark, B → X_{c}ℓν. The variable n_{X}^{2} is a combination of the invariant mass of the charmed meson m_{X}, its energy in the B-meson rest-frame E_{X;BRF}, and a constant ~Λ = 0.65 GeV, n_{X}^{2} = m_{X}^{2}c^{4}-2~ΛE_{X,BRF} + ~Λ^{2}. The moments
Crustal evolution inferred from Apollo magnetic measurements
NASA Technical Reports Server (NTRS)
Dyal, P.; Daily, W. D.; Vanyan, L. L.
1978-01-01
Magnetic field and solar wind plasma density measurements were analyzed to determine the scale size characteristics of remanent fields at the Apollo 12, 15, and 16 landing sites. Theoretical model calculations of the field-plasma interaction, involving diffusion of the remanent field into the solar plasma, were compared to the data. The information provided by all these experiments shows that remanent fields over most of the lunar surface are characterized by spatial variations as small as a few kilometers. Large regions (50 to 100 km) of the lunar crust were probably uniformly magnetized during early crustal evolution. Bombardment and subsequent gardening of the upper layers of these magnetized regions left randomly oriented, smaller scale (5 to 10 km) magnetic sources close to the surface. The larger scale size fields of magnitude approximately 0.1 gammas are measured by the orbiting subsatellite experiments and the small scale sized remanent fields of magnitude approximately 100 gammas are measured by the surface experiments.
MAGNETIC FIELD MEASUREMENTS FOR FAST-CHANGING MAGNETIC FIELDS.
JAIN, A.; ESCALLIER, J.; GANETIS, G.; LOUIE, W.; MARONE, A.; THOMAS. R.; WANDERER, P.
2004-10-03
Several recent applications for fast ramped magnets have been found that require rapid measurement of the field quality during the ramp. (In one instance, accelerator dipoles will be ramped at 1 T/sec, with measurements needed to the accuracy typically required for accelerators.) We have built and tested a new type of magnetic field measuring system to meet this need. The system consists of 16 stationary pickup windings mounted on a cylinder. The signals induced in the windings in a changing magnetic field are sampled and analyzed to obtain the field harmonics. To minimize costs, printed circuit boards were used for the pickup windings and a combination of amplifiers and ADPs used for the voltage readout system. New software was developed for the analysis. Magnetic field measurements of a model dipole developed for the SIS200 accelerator at GSI are presented. The measurements are needed to insure that eddy currents induced by the fast ramps do not impact the field quality needed for successful accelerator operation.
Magnetic Field Response Measurement Acquisition System
NASA Technical Reports Server (NTRS)
Woodard, Stanley E.; Taylor,Bryant D.; Shams, Qamar A.; Fox, Robert L.
2007-01-01
This paper presents a measurement acquisition method that alleviates many shortcomings of traditional measurement systems. The shortcomings are a finite number of measurement channels, weight penalty associated with measurements, electrical arcing, wire degradations due to wear or chemical decay and the logistics needed to add new sensors. Wire degradation has resulted in aircraft fatalities and critical space launches being delayed. The key to this method is the use of sensors designed as passive inductor-capacitor circuits that produce magnetic field responses. The response attributes correspond to states of physical properties for which the sensors measure. Power is wirelessly provided to the sensing element by using Faraday induction. A radio frequency antenna produces a time-varying magnetic field used to power the sensor and receive the magnetic field response of the sensor. An interrogation system for discerning changes in the sensor response frequency, resistance and amplitude has been developed and is presented herein. Multiple sensors can be interrogated using this method. The method eliminates the need for a data acquisition channel dedicated to each sensor. The method does not require the sensors to be near the acquisition hardware. Methods of developing magnetic field response sensors and the influence of key parameters on measurement acquisition are discussed. Examples of magnetic field response sensors and the respective measurement characterizations are presented. Implementation of this method on an aerospace system is discussed.
Magnetic space-based field measurements
NASA Technical Reports Server (NTRS)
Langel, R. A.
1981-01-01
Satellite measurements of the geomagnetic field began with the launch of Sputnik 3 in May 1958 and have continued sporadically in the intervening years. A list of spacecraft that have made significant contributions to an understanding of the near-earth geomagnetic field is presented. A new era in near-earth magnetic field measurements began with NASA's launch of Magsat in October 1979. Attention is given to geomagnetic field modeling, crustal magnetic anomaly studies, and investigations of the inner earth. It is concluded that satellite-based magnetic field measurements make global surveys practical for both field modeling and for the mapping of large-scale crustal anomalies. They are the only practical method of accurately modeling the global secular variation. Magsat is providing a significant contribution, both because of the timeliness of the survey and because its vector measurement capability represents an advance in the technology of such measurements.
NASA Astrophysics Data System (ADS)
de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.
2010-05-01
The purpose of the present work is to theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a non-magnetic s-p Mössbauer 119Sn impurity diluted on R sites ( R=rare-earth metals) of the cubic Laves phases intermetallic compounds RFe2. One considers that the magnetic hyperfine field has two contributions (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24 (1963) 1601] model and (ii) the contribution from the induced magnetic moments arising from the Fe neighboring sites. We have in this case a two-center Blandin-Campbell-like [Phys. Rev. Lett. 31 (1973) 51; J. Magn. Magn. Mater. 1 (1975) 1] problem, where a magnetic 3d-element located at a distance from the 119Sn impurity gives an extra magnetization to a polarized electron gas which is strongly charge perturbed at the 119Sn impurity site. We also include in the model, the nearest-neighbor perturbation due to the translational invariance breaking introduced by the impurity. Our self-consistent total magnetic hyperfine field calculations are in a very good agreement with recent experimental data.
Simms, D A; Butterfield, C P
1991-10-01
Two methods can be used to determine aerodynamic loads on a rotating wind turbine blade. The first is to make direct pressure measurements on the blade surface. This is a difficult process requiring costly pressure instrumentation. The second method uses measured flap bending moments in conjunction with analytical techniques to estimate airloads. This method, called ALEST, was originally developed for use on helicopter rotors and was modified for use on horizontal axis wind turbine blades. Estimating airloads using flap bending moments in much simpler and less costly because measurements can be made with conventional strain gages and equipment. This paper presents results of airload estimates obtained using both methods under a variety of operating conditions. Insights on the limitations and usefulness of the ALEST bending moment technique are also included. 10 refs., 6 figs.
NASA Astrophysics Data System (ADS)
Arribas, Enrique; Escobar, Isabel; Suarez, Carmen P.; Najera, Alberto; Beléndez, Augusto
2015-11-01
In this work, we propose an inexpensive laboratory practice for an introductory physics course laboratory for any grade of science and engineering study. This practice was very well received by our students, where a smartphone (iOS, Android, or Windows) is used together with mini magnets (similar to those used on refrigerator doors), a 20 cm long school rule, a paper, and a free application (app) that needs to be downloaded and installed that measures magnetic fields using the smartphone’s magnetic field sensor or magnetometer. The apps we have used are: Magnetometer (iOS), Magnetometer Metal Detector, and Physics Toolbox Magnetometer (Android). Nothing else is needed. Cost of this practice: free. The main purpose of the practice is that students determine the dependence of the component x of the magnetic field produced by different magnets (including ring magnets and sphere magnets). We obtained that the dependency of the magnetic field with the distance is of the form x-3, in total agreement with the theoretical analysis. The secondary objective is to apply the technique of least squares fit to obtain this exponent and the magnetic moment of the magnets, with the corresponding absolute error.
Hu, Hai-Long; Zeng, Rong; Pham, Anh; Tan, Thiam Teck; Chen, Zhigang; Kong, Charlie; Wang, Danyang; Li, Sean
2016-06-01
Clarification of the role of magnetic ordering and scattering in two-dimensional electron gas has become increasingly important to understand the transport and magnetic behavior in the LaAlO3 (LAO)/SrTiO3 (STO) heterostructures. In this work, we report the sheet resistance of the LAO/STO heterostructures as functions of temperature, magnetic field, and field orientation. An unexpected resistance minimum was discovered at ∼10 K under a sufficiently high in-plane magnetic field. An anisotropic magnetoresistance (MR) is clearly identified, indicating the presence of magnetic scattering which may be related to the interaction between itinerant electrons and localized magnetic moments in the LaAlO3/SrTiO3 heterostructures. It is believed that the high concentration of oxygen vacancies induced by the ultralow oxygen partial pressure during the deposition process plays a predominant role in the occurrence of the anisotropic MR. PMID:27186855
Magnetic Field Response Measurement Acquisition System
NASA Technical Reports Server (NTRS)
Woodward, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)
2007-01-01
Magnetic field response sensors designed as passive inductor- capacit or circuits produce magnetic field responses whose harmonic frequenci es correspond to states of physical properties for which the sensors measure. Power to the sensing element is acquired using Faraday induc tion. A radio frequency antenna produces the time varying magnetic fi eld used for powering the sensor, as well as receiving the magnetic field response of the sensor. An interrogation architecture for disce rning changes in sensor's response frequency, resistance and amplitud e is integral to the method thus enabling a variety of measurements. Multiple sensors can be interrogated using this method, thus eliminat ing the need to have a data acquisition channel dedicated to each se nsor. The method does not require the sensors to be in proximity to a ny form of acquisition hardware. A vast array of sensors can be used as interchangeable parts in an overall sensing system.
Magnetic Field Response Measurement Acquisition System
NASA Technical Reports Server (NTRS)
Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, Christopher L. (Inventor); Fox, Melanie L. (Inventor); Bryant, Robert G. (Inventor)
2006-01-01
Magnetic field response sensors designed as passive inductor-capacitor circuits produce magnetic field responses whose harmonic frequencies correspond to states of physical properties for which the sensors measure. Power to the sensing element is acquired using Faraday induction. A radio frequency antenna produces the time varying magnetic field used for powering the sensor, as well as receiving the magnetic field response of the sensor. An interrogation architecture for discerning changes in sensor s response kequency, resistance and amplitude is integral to the method thus enabling a variety of measurements. Multiple sensors can be interrogated using this method, thus eliminating the need to have a data acquisition channel dedicated to each sensor. The method does not require the sensors to be in proximity to any form of acquisition hardware. A vast array of sensors can be used as interchangeable parts in an overall sensing system.
NASA Astrophysics Data System (ADS)
Soria, Julio; Atkinson, Callum
2013-11-01
This work shows how the joint probability density function (JPDF) of the streamwise and wall normal velocity components of a zero-pressure gradient turbulent boundary layer (ZPG-TBL) can be directly measured using the methodology and theoretical framework proposed by Soria & Willert (2012) MST 23, 065301. Higher order moments including Reynolds stresses can be computed directly from two-component (2C) JPDFs of the streamwise and wall normal velocity components by taking moments of the 2C-JPDF. The base data for the direct measurement of the 2C-JPDF are single-exposed image pairs typically used to determine instantaneous 2C-2D particle image velocimetry (PIV) fields. However, in the new direct measurement method, the instantaneous velocity samples necessary to build up the JPDF never need to be determined, which avoids the problems in PIV due to large velocity gradients that are typically encountered in turbulent wall-bounded flows. This new method has been applied to single-exposed image pairs acquired over a range of Reynolds numbers ranging up to Reτ = 19500 in ZPG-TBL experiments. This paper presents directly measured 2C-JPDFs across the ZPG-TBL as well as higher moment distributions determined from these 2C-JPDFs. The financial support of the Australian Research Council to undertake this research is gratefully acknowledged.
NASA Astrophysics Data System (ADS)
Meng, Tao; Matunaga, Saburo
2012-04-01
This paper focuses on the attitude control problem of small agile satellites using single-gimbal control moment gyros (CMG) and magnetic torquers (MTQ). CMGs are regarded as effective torque generators for agile satellites because of their torque amplification capability. However, they are vulnerable to failure due to their complex inner mechanism. In this paper, different failure cases of CMGs are analyzed. A flexible failure-tolerant control strategy is developed by automatically redistributing the required control torque among the operating CMGs and MTQs, with a variable limiter to accommodate the actuator dynamics changes introduced by CMG failures. The performances of maneuvers about different directions under different failure cases are also discussed and examined. Numerical simulations demonstrate that the proposed strategy maintains certain agility in the cases of one or two CMGs failing. Moreover, a survival strategy with only one CMG left is also verified. Both sun-pointing stabilization and earth-pointing stabilization can be achieved in this case, which fulfill some basic mission requirements.
Gozdz, Marek; Kaminski, Wieslaw A.; Simkovic, Fedor; Faessler, Amand
2006-09-01
The transition magnetic moments of Majorana neutrinos {mu}{sub {nu}{sub ij}} (ij=e{mu}, e{tau}, {mu}{tau}) are calculated in grand unified theory (GUT) constrained Minimal Supersymmetric Standard Model (MSSM) with explicit R-parity violation. It is assumed that neutrinos acquire masses via one-loop (quark-squark and lepton-slepton) radiative corrections. The mixing of squarks, sleptons, and quarks is considered explicitly. The connection between {mu}{sub {nu}{sub ij}} and the entries of neutrino mass matrix is studied. The current upper limits on {mu}{sub {nu}{sub ij}} are deduced from the elements of phenomenological neutrino mass matrix, which is reconstructed using the neutrino oscillation data and the lower bound on the neutrinoless double beta decay half-life. Further, the results for {mu}{sub {nu}{sub e}{sub {mu}}}, {mu}{sub {nu}{sub e}{sub {tau}}} and {mu}{sub {nu}{sub {mu}}{sub {tau}}} are presented for the cases of inverted and normal hierarchy of neutrino masses and different SUSY scenarios. The largest values are of the order of 10{sup -17} in units of Bohr magneton.
DC-magnetic field vector measurement
NASA Technical Reports Server (NTRS)
Schmidt, R.
1981-01-01
A magnetometer experiment was designed to determine the local magnetic field by measuring the total of the Earth's magnetic field and that of an unknown spacecraft. The measured field vector components are available to all onboard experiments via the Spacelab command and data management system. The experiment consists of two parts, an electronic box and the magnetic field sensor. The sensor includes three independent measuring flux-gate magnetometers, each measuring one component. The physical background is the nonlinearity of the B-H curve of a ferrite material. Two coils wound around a ferrite rod are necessary. One of them, a tank coil, pumps the ferrite rod at approximately 20 kilohertz. As a consequence of the nonlinearity, many harmonics can be produced. The second coil (i.e., the detection coil) resonates to the first harmonic. If an unknown dc or low-frequency magnetic field exists, the amplitude of the first harmonic is a measure for the unknown magnetic field. The voltages detected by the sensors are to be digitized and transferred to the command and data management system.
Muon anomalous magnetic moment and positron excess at AMS-02 in a gauged horizontal symmetric model
NASA Astrophysics Data System (ADS)
Tomar, Gaurav; Mohanty, Subhendra
2014-11-01
We studied an extension of the standard model with a fourth generation of fermions to explain the discrepancy in the muon ( g -2) and explain the positron excess seen in the AMS-02 experiment. We introduce a gauged SU(2)HV horizontal symmetry between the muon and the 4th generation lepton families. The 4th generation right-handed neutrino is identified as the dark matter with mass ~ 700GeV. The dark matter annihilates only to ( μ + μ -) and ( ν {/μ C } ν μ ) states via SU(2)HV gauge boson. The SU(2)HV gauge boson with mass ~ 1.4 TeV gives an adequate contribution to the ( g - 2) of muon and fulfill the experimental constraint from BNL measurement. The higgs production constraints from 4th generation fermions is evaded by extending the higgs sector.
Bulk magnetic measurements and Ru99 and Gd155 Mössbauer spectroscopies of Gd2Ru2O7
NASA Astrophysics Data System (ADS)
Gurgul, J.; Rams, M.; Świątkowska, Ż.; Kmieć, R.; Tomala, K.
2007-02-01
Bulk magnetic measurements and Ru99 and Gd155 Mössbauer effect investigations were performed to examine magnetic properties of the gadolinium pyrochlore ruthenate Gd2Ru2O7 . A magnetic transition to the antiferromagnetic state at TN=114(1)K is accompanied by a small difference between field-cooled and zero-field-cooled magnetic susceptibilities. Ru99 and Gd155 Mössbauer effect investigations at 4.2K confirmed that both ruthenium and gadolinium sublattices are magnetically ordered. Successful analysis of each spectrum with one set of hyperfine parameters proves that all ruthenium moments have the same magnitude and form the same angle with the local three-fold symmetry axes. The same conclusion concerns Gd magnetic moments. The measured temperature dependence of the hyperfine field at Gd site, together with the molecular-field model, points to the fact that Gd moments also order at TN , with tiny magnetic moments due to Gd-Ru exchange interaction.
NASA Astrophysics Data System (ADS)
Hailey, C. E.; Clark, E. L.; Cole, J. K.
High-speed water-entry is a very complex, dynamic process. As a first attempt at modeling the process, a numerical solution was developed at Sandia National Laboratories for predicting the forces and moments acting on a body with a steady supercavity, that is, a cavity which extends beyond the base of the body. The solution is limited to supercavities on slender, axisymmetric bodies at small angles of attack. Limited data were available with which to benchmark the axial force predictions at zero angle of attack. Even less data were available with which to benchmark the pitching moment and normal force predictions at nonzero angles of attack. A water tunnel test was conducted to obtain force and moment data on a slender shape. This test produced limited data because of waterproofing problems with the balance. A new balance was designed and a second water tunnel test was conducted at Tracor Hydronautics, Inc. This paper describes the numerical solution, the experimental equipment and test procedures, and the results of the second test.
M. Osipenko; G. Ricco; S. Simula; M. Battaglieri; M. Ripani; the CLAS Collaboration
2005-06-02
Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F2 with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasi-elastic peak up to the invariant mass of the final-state hadronic system W {approx} 2.7 GeV with four-momentum transfers Q2 from 0.4 to 6 (GeV/c){sup 2}. These data are complementary to previous measurements of the proton structure function F2 and cover a similar two-dimensional region of Q2 and Bjorken variable x. Determination of the deuteron F2 over a large x interval including the quasi-elastic peak as a function of Q2, together with the other world data, permit a direct evaluation of the structure function moments for the first time. By fitting the Q2 evolution of these moments with an OPE-based twist expansion we have obtained a separation of the leading twist and higher twist terms. The observed Q2 behavior of the higher twist contribution suggests a partial cancellation of different higher twists entering into the expansion with opposite signs. This cancellation, found also in the proton moments, is a manifestation of the ''duality'' phenomenon in the F2 structure function.
NASA Astrophysics Data System (ADS)
Yoder, Jacob
The Neutron Electric Dipole Moment (nEDM) experiment that will take place at the Spallation Neutron Source (SNS) in Oak Ridge, Tennessee will measure the electric dipole moment (EDM) of the neutron with a precision of order 10-28 e-cm, utilizing spin-polarized 3He in bulk liquid 4He to detect neutron precession in a 10 mG magnetic field and 50 kV/cm electric field. Since depolarized 3He will produce a background, relaxation of the polarized 3He, characterized by the probability of depolarization per bounce, Pd, was measured for materials that will be in contact with polarized 3He. Depolarization probabilities were determined from measurements of the longitudinal relaxation time of polarized 3He in bulk liquid 4He inside an acrylic cell coated with the wavelength shifter deuterated tetraphenyl butadiene (d-TPB), which will be used to coat the nEDM measurement cell. Relaxation measurements were also performed while rods, made from plumbing material Torlon and valve bellows material BeCu, were present in the cell. The BeCu was coated with Pyralin resin prior to relaxation measurements, while relaxation measurements were performed both before and after the Torlon rod was coated with Pyralin resin. The depolarization probabilities were found to be Pd-TPBd <1.32x10-7 PBareTorlon d=1.01+/-0.08 x10-6 PCoatedTorlon d=2.5+/-0.1 x10-7 PCoatedBeCu d=7.9+/-0.3 x10-7 The relaxation rates extrapolated from the observed values of Pd for d-TPB, coated Torlon, and coated BeCu in the nEDM apparatus were found to be consistent with design goals.
An instrument for precision magnetic measurements of large magnetic structures
NASA Astrophysics Data System (ADS)
Beltrán, D.; Bordas, J.; Campmany, J.; Molins, A.; Perlas, J. A.; Traveria, M.
2001-02-01
A high precision-system for measuring the three-dimensional distribution of magnetic fields over large volumes, such as those produced by accelerator magnets, has been designed and commissioned. This instrument can be calibrated to a precision of ±1 G for magnetic fields of up to 1.5 T by means of an NMR system. A moving arm containing a 3D Hall probe scans the volume (up to 500×250×3000 mm 3) with a precision of ±50 μm in any direction. After appropriate identification of the various sources of error, and the optimisation of the various parts of the instrument where they are generated, an overall precision of ±2 G has been achieved, i.e. a relative precision of ±2×10 -4 for a nominal field of 1 T.
ERIC Educational Resources Information Center
Williams, Kate
2012-01-01
The informatics moment is the moment when a person seeks help in using some digital technology that is new to him or her. This article examines the informatics moment in people's everyday lives as they sought help at a branch public library. Four types of literacy were involved: basic literacy (reading and writing), computer literacy (use of a…
Direct measurements of the magnetic entropy change
NASA Astrophysics Data System (ADS)
Nielsen, K. K.; Bez, H. N.; von Moos, L.; Bjørk, R.; Eriksen, D.; Bahl, C. R. H.
2015-10-01
An experimental device that can accurately measure the magnetic entropy change, Δs, as a function of temperature, T, and magnetic field, H, is presented. The magnetic field source is in this case a set of counter-rotating concentric Halbach-type magnets, which produce a highly homogeneous applied field with constant orientation. The field may be varied from 0 to 1.5 T in a continuous way. The temperature stability of the system is controlled to within ±10 mK and the standard range for the current setup is from 230 K to 330 K. The device is under high vacuum and we show that thermal losses to the ambient are negligible in terms of the calorimetric determination of the magnetic entropy change, while the losses cannot be ignored when correcting for the actual sample temperature. We apply the device to two different types of samples; one is commercial grade Gd, i.e., a pure second-order phase transition material, while the other is Gd5Si2Ge2, a first order magnetic phase transition material. We demonstrate the device's ability to fully capture the thermal hysteresis of the latter sample by following appropriate thermal resetting scheme and magnetic resetting scheme.
Boundaries for efficient use of electron vortex beams to measure magnetic properties.
Rusz, Ján; Bhowmick, Somnath
2013-09-01
Development of experimental techniques for characterization of magnetic properties at high spatial resolution is essential for progress in miniaturization of magnetic devices, for example, in data storage media. Inelastic scattering of electron vortex beams (EVBs) was recently reported to contain atom-specific magnetic information. We develop a theoretical description of inelastic scattering of EVBs on crystals and perform simulations for EVBs of different diameters. We show that use of an EVB wider than an interatomic distance does not provide any advantage over an ordinary convergent beam without angular momentum. On the other hand, in the atomic-resolution limit, electron energy loss spectra measured by EVBs are strongly sensitive to the spin and orbital magnetic moments of studied matter, when channeling through or very close to the atomic columns. Our results demonstrate the boundaries for efficient use of EVBs in measurement of magnetic properties. PMID:25166681
Fan, Zhaoyang; Zhou, Xiangzhi; Bi, Xiaoming; Dharmakumar, Rohan; Carr, James C; Li, Debiao
2011-04-01
Flow-sensitive dephasing (FSD) magnetization preparation has been developed for black-blood vessel wall MRI and noncontrast MR angiography. The first-order gradient moment, m(1) , is a measure of the flow-sensitization imparted by an FSD preparative module. Determination of the optimal m(1) for each individual is highly desirable for FSD-prepared MR angiography. This work developed a 2D m(1)-scouting method that evaluates a range of m(1) values for their effectiveness in blood signal suppression in a single scan. The feasibility of using the 2D method to predict blood signal suppression in 3D FSD-prepared imaging was validated on a flow phantom and the popliteal arteries of 5 healthy volunteers. Excellent correlation of the blood signal measurements between the 2D scouting and 3D FSD imaging was obtained. Therefore, the optimal m(1) determined from the 2D m(1)-scouting scan may be directly translated to 3D FSD-prepared imaging. In vivo studies of additional 10 healthy volunteers and 2 patients have demonstrated the proposed method can help significantly improve the signal performance of FSD MR angiography, indicating its potential to enhance diagnostic confidence. Further systematic studies in patients are warranted to evaluate its clinical value.
NASA Astrophysics Data System (ADS)
Ortenzi, L.; Gretarsson, H.; Kasahara, S.; Matsuda, Y.; Shibauchi, T.; Finkelstein, K. D.; Wu, W.; Julian, S. R.; Kim, Young-June; Mazin, I. I.; Boeri, L.
2015-01-01
We report a combination of Fe K β x-ray emission spectroscopy and density functional reduced Stoner theory calculations to investigate the correlation between structural and magnetic degrees of freedom in CaFe2(As1-xPx) 2 . The puzzling temperature behavior of the local moment found in rare earth-doped CaFe2As2 [H. Gretarsson et al., Phys. Rev. Lett. 110, 047003 (2013)] is also observed in CaFe2(As1-xPx) 2 . We explain this phenomenon based on first-principles calculations with scaled magnetic interaction. One scaling parameter is sufficient to describe quantitatively the magnetic moments in both CaFe2(As1-xPx) 2 (x =0.055 ) and Ca0.78La0.22Fe2As2 at all temperatures. The anomalous growth of the local moments with increasing temperature can be understood from the observed large thermal expansion of the c -axis lattice parameter combined with strong magnetoelastic coupling. These effects originate from the strong tendency to form As-As dimers across the Ca layer in the CaFe2As2 family of materials. Our results emphasize the dual local-itinerant character of magnetism in Fe pnictides.
Ortenzi, L; Gretarsson, H; Kasahara, S; Matsuda, Y; Shibauchi, T; Finkelstein, K D; Wu, W; Julian, S R; Kim, Young-June; Mazin, I I; Boeri, L
2015-01-30
We report a combination of Fe Kβ x-ray emission spectroscopy and density functional reduced Stoner theory calculations to investigate the correlation between structural and magnetic degrees of freedom in CaFe2(As1-xPx)2. The puzzling temperature behavior of the local moment found in rare earth-doped CaFe2As2 [H. Gretarsson et al., Phys. Rev. Lett. 110, 047003 (2013)] is also observed in CaFe2(As1-xPx)2. We explain this phenomenon based on first-principles calculations with scaled magnetic interaction. One scaling parameter is sufficient to describe quantitatively the magnetic moments in both CaFe2(As1-xPx)2 (x=0.055) and Ca0.78La0.22Fe2As2 at all temperatures. The anomalous growth of the local moments with increasing temperature can be understood from the observed large thermal expansion of the c-axis lattice parameter combined with strong magnetoelastic coupling. These effects originate from the strong tendency to form As-As dimers across the Ca layer in the CaFe2As2 family of materials. Our results emphasize the dual local-itinerant character of magnetism in Fe pnictides. PMID:25679903
Comparative magnetic measurements on social insects
NASA Astrophysics Data System (ADS)
Ferreira, Jandira; Cernicchiaro, Geraldo; Winklhofer, Michael; Dutra, Humberto; de Oliveira, Paulo S.; S. Esquivel, Darci M.; Wajnberg, Eliane
2005-03-01
Biogenic magnetite has been detected in several species of social insects and may well form the basis of a magnetic sensory system in these animals, although other physiological functions are possible, too. We report here on hysteresis measurements on honeybees ( Apis mellifera) and the termite Neocapritermes opacus. The ratio of saturation remanence to saturation magnetization, Jrs/ Js, was determined as 0.11 (0.15) in bees (termite), the coercive force Hc as 90 (50 Oe). The magnetic remanence is generally low (of the order of 10 -6 emu per individual). The values obtained are similar to the ones reported previously on a migratory ant species, which suggests that biomineralization of magnetic material in social insects may underlie a generic process.
Artifacts in magnetic measurements of fluid samples
NASA Astrophysics Data System (ADS)
Boekelheide, Z.; Dennis, C. L.
2016-08-01
Applications of magnetic fluids are ever increasing, as well as the corresponding need to be able to characterize these fluids in situ. Commercial magnetometers are accurate and well-characterized for solid and powder samples, but their use with fluid samples is more limited. Here, we describe artifacts which can occur in magnetic measurements of fluid samples and their impact. The most critical problem in the measurement of fluid samples is the dynamic nature of the sample position and size/shape. Methods to reduce these artifacts are also discussed, such as removal of air bubbles and dynamic centering.
Absolute method of measuring magnetic susceptibility
Thorpe, A.; Senftle, F.E.
1959-01-01
An absolute method of standardization and measurement of the magnetic susceptibility of small samples is presented which can be applied to most techniques based on the Faraday method. The fact that the susceptibility is a function of the area under the curve of sample displacement versus distance of the magnet from the sample, offers a simple method of measuring the susceptibility without recourse to a standard sample. Typical results on a few substances are compared with reported values, and an error of less than 2% can be achieved. ?? 1959 The American Institute of Physics.
NASA Astrophysics Data System (ADS)
Masrour, R.; Hlil, E. K.
2016-08-01
Self-consistent ab initio calculations based on density-functional theory and using both full potential linearized augmented plane wave and Korring-Kohn-Rostoker-coherent potential approximation methods, are performed to investigate both electronic and magnetic properties of the Ga1-xMnxN system. Magnetic moments considered to lie along (001) axes are computed. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters such as the magnetic phase diagram and the critical exponent. The increasing of the dilution x in this system has allowed to verify a series of HTSEs predictions on the possibility of ferromagnetism in dilute magnetic insulators and to demonstrate that the interaction changes from antiferromagnetic to ferromagnetic passing through the spins glace phase.
Constraining parity violation in gravity with measurements of neutron-star moments of inertia
Yunes, Nicolas; Psaltis, Dimitrios; Oezel, Feryal; Loeb, Abraham
2010-03-15
Neutron stars are sensitive laboratories for testing general relativity, especially when considering deviations where velocities are relativistic and gravitational fields are strong. One such deviation is described by dynamical, Chern-Simons modified gravity, where the Einstein-Hilbert action is modified through the addition of the gravitational parity-violating Pontryagin density coupled to a field. This four-dimensional effective theory arises naturally both in perturbative and nonperturbative string theory, loop quantum gravity, and generic effective field theory expansions. We calculate here Chern-Simons modifications to the properties and gravitational fields of slowly spinning neutron stars. We find that the Chern-Simons correction affects only the gravitomagnetic sector of the metric to leading order, thus introducing modifications to the moment-of-inertia but not to the mass-radius relation. We show that an observational determination of the moment-of-inertia to an accuracy of 10%, as is expected from near-future observations of the double pulsar, will place a constraint on the Chern-Simons coupling constant of {xi}{sup 1/4} < or approx. 5 km, which is at least three-orders of magnitude stronger than the previous strongest bound.