Polarized Radiative Transfer in Fluctuating Stochastic Media

International Nuclear Information System (INIS)

Sallah, M.; Degheidy, A.R.; Selim, M.M.

2009-01-01

The problem of polarized radiative transfer in a planar cluttered atmospheric medium (like cloudy atmosphere) is proposed. The solution is presented for an arbitrary absorption and scattering cross sections. The extinction function of the medium is assumed to be a continuous random function of position, with fluctuations about the mean taken as Gaussian distributed. The joint probability distribution function of these Gaussian random variables is used to calculate the ensemble-averaged quantities, such as reflectivity, radiative energy and radiative flux, for an arbitrary correlation function. A modified Gaussian probability distribution function is also used to average the solution in order to exclude the probable negative values of the optical variable. The problem is considered in half space medium which has specular reflecting boundary exposed to unit external incident flux. Numerical results of the average reflectivity, average radiant energy and average net flux are obtained for both Gaussian and modified Gaussian probability density functions at different degrees of polarization

Lactational transfer of mercury and polychlorinated biphenyls in polar bears.

Science.gov (United States)

Knott, Katrina K; Boyd, Daryle; Ylitalo, Gina M; O'Hara, Todd M

2012-07-01

We examined concentrations of total mercury (tHg, inorganic and methylated forms) and polychlorinated biphenyls (PCBs) in blood and milk from free-ranging Southern Beaufort-Chukchi Sea polar bears (Ursus maritimus) to assess maternal transfer of contaminants during lactation and the potential health risk to nursing young. Concentrations of contaminants in the blood of dependent and juvenile animals (ages 1-5 years) ranged from 35.9 to 52.2 μg kg(-1) ww for tHg and 13.9 to 52.2 μg kg(-1) ww (3255.81-11067.79 μg kg(-1) lw) for ΣPCB(7)s, similar to those of adult females, but greater than adult males. Contaminant concentrations in milk ranged from 5.7 to 71.8 μg tHg kg(-1)ww and 160 to 690 μg ΣPCB(11)s kg(-1) ww (547-5190 μg kg(-1) lw). The daily intake levels for tHg by milk consumption estimated for dependent young were below the tolerable daily intake level (TDIL) of tHg established for adult humans. Although the daily intake levels of PCBs through milk consumption for cubs of the year exceeded the TDIL thresholds, calculated dioxin equivalents for PCBs in milk were below adverse physiological thresholds for aquatic mammals. Relatively high concentrations of non-dioxin like PCBs in polar bear milk and blood could impact endocrine function of Southern Beaufort-Chukchi Sea polar bears, but this is uncertain. Transfer of contaminants during mid to late lactation likely limits bioaccumulation of dietary contaminants in female polar bears during spring. As polar bears respond to changes in their arctic sea ice habitat, the adverse health impacts associated with nutritional stress may be exacerbated by tHg and PCBs exposure, especially in ecologically and toxicologically sensitive polar bear cohorts such as reproductive females and young. Copyright © 2012. Published by Elsevier Ltd.

Analyzing powers and proton spin transfer coefficients in the elastic scattering of 800 MeV polarized protons from an L-type polarized deuteron target at small momentum transfers

International Nuclear Information System (INIS)

Adams, D.L.

1986-10-01

Analyzing powers and spin transfer coefficients which describe the elastic scattering of polarized protons from a polarized deuteron target have been measured. The energy of the proton beam was 800 MeV and data were taken at laboratory scattering angles of 7, 11, 14, and 16.5 degrees. One analyzing power was also measured at 180 degrees. Three linearly independent orientations of the beam polarization were used and the target was polarized parallel and antiparallel to the direction of the beam momentum. The data were taken with the high resolution spectrometer at the Los Alamos Meson Physics Facility (experiment 685). The results are compared with multiple scattering predictions based on Dirac representations of the nucleon-nucleon scattering matrices. 27 refs., 28 figs., 4 tabs

Polarization transfer in x-ray transitions due to photoionization in highly charged copper-like ions

Science.gov (United States)

Ma, Kun; Chen, Zhan-Bin; Xie, Lu-You; Dong, Chen-Zhong

2018-02-01

Using the density matrix theory and the multi-configuration Dirac-Fock method, the 3{d}3/2 subshell photoionization of highly charged ions is studied, together with their subsequent radiative decay. The effects of polarization transfer on the linear polarization and angular distribution of the 3{d}94{s}2{}2{D}3/2\\to 3{d}104p{}2{P}1/2 characteristic line photoemission for selected Cu-like Zn+, Ba27+, {{{W}}}45+, and {{{U}}}63+ ions are investigated. Our results show that the polarization transfer, arising from the originally polarized incident light, may lead to a considerable change in the alignment parameters and the polarization properties of the radiation, the character of which is highly sensitive to the initial photon polarization, yet virtually independent of the photon energy. These characteristics are very similar to those of the electron bremsstrahlung process reported by Märtin et al (2012 Phys. Rev. Lett. 108 264801). The present results are compared with available experimental results and show a good quantitative agreement.

Arcmancer: Geodesics and polarized radiative transfer library

Science.gov (United States)

Pihajoki, Pauli; Mannerkoski, Matias; Nättilä, Joonas; Johansson, Peter H.

2018-05-01

Arcmancer computes geodesics and performs polarized radiative transfer in user-specified spacetimes. The library supports Riemannian and semi-Riemannian spaces of any dimension and metric; it also supports multiple simultaneous coordinate charts, embedded geometric shapes, local coordinate systems, and automatic parallel propagation. Arcmancer can be used to solve various problems in numerical geometry, such as solving the curve equation of motion using adaptive integration with configurable tolerances and differential equations along precomputed curves. It also provides support for curves with an arbitrary acceleration term and generic tools for generating ray initial conditions and performing parallel computation over the image, among other tools.

Polarization tunable photogenerated carrier transfer of CH3NH3PbI3/polyvinylidene fluoride heterostructure

Science.gov (United States)

Yang, Kang; Deng, Zun-Yi; Feng, Hong-Jian

2017-10-01

The integration of ferroelectrics and organic-inorganic halide perovskites could be a promising way to facilitate the separation of electron-hole pairs and charge extraction for the application of solar cells. To explore the effect of the external ferroelectric layer on the CH3NH3PbI3 (MAPbI3) side, we perform first-principles calculations to study the charge transfer properties of the MAPbI3/polyvinylidene fluoride (PVDF) heterostructure. Our calculations demonstrate that the ferroelectric polarization pointing to the PVDF side can clearly facilitate the separation of photo-induced carriers and enhance charge extraction from MAPbI3, while opposite polarization direction hinders the charge extraction and collection. Notably, the carrier behavior at the interface is strongly tuned by the electric field associated with the ferroelectric polarization. In addition, excited state simulation confirms the tunable charge transfer of the MAPbI3/PVDF heterojunction. Therefore, the polarization-driven charge transfer mechanism provides a route for fabricating the ferroelectrics-based high-efficiency photovoltaics and switchable diode devices.

Spin transfers for baryon production in polarized pp collisions at RHIC-BNL

International Nuclear Information System (INIS)

Ma BoQiang; Schmidt, Ivan; Soffer, Jacques; Yang Jianjun

2002-01-01

We consider the inclusive production of longitudinally polarized baryons in p→p collisions at RHIC-BNL, with one longitudinally polarized proton. We study the spin transfer between the initial proton and the produced baryon as a function of its rapidity and we elucidate its sensitivity to the quark helicity distributions of the proton and to the polarized fragmentation functions of the quark into the baryon. We make predictions using an SU(6) quark spectator model and a perturbative QCD (pQCD) based model. We discuss these different predictions, and what can be learned from them, in view of the forthcoming experiments at RHIC-BNL

On the derivation of vector radiative transfer equation for polarized radiative transport in graded index media

International Nuclear Information System (INIS)

Zhao, J.M.; Tan, J.Y.; Liu, L.H.

2012-01-01

Light transport in graded index media follows a curved trajectory determined by Fermat's principle. Besides the effect of variation of the refractive index on the transport of radiative intensity, the curved ray trajectory will induce geometrical effects on the transport of polarization ellipse. This paper presents a complete derivation of vector radiative transfer equation for polarized radiation transport in absorption, emission and scattering graded index media. The derivation is based on the analysis of the conserved quantities for polarized light transport along curved trajectory and a novel approach. The obtained transfer equation can be considered as a generalization of the classic vector radiative transfer equation that is only valid for uniform refractive index media. Several variant forms of the transport equation are also presented, which include the form for Stokes parameters defined with a fixed reference and the Eulerian forms in the ray coordinate and in several common orthogonal coordinate systems.

Polar transfer alignment of shipborne SINS with a large misalignment angle

International Nuclear Information System (INIS)

Cheng, Jianhua; Wang, Tongda; Guan, Dongxue; Li, Meiling

2016-01-01

Existing polar transfer alignment (TA) algorithms are designed based on linear Kalman filters (KF) to estimate misalignment angles. In the case of a large misalignment angle, these algorithms cannot be applied in order to achieve accurate TA. In this paper, a TA algorithm based on an unscented Kalman filter (UKF) is proposed to solve the problem of the large misalignment angle in the polar region. Based on a large misalignment angle, nonlinear navigation error equations, which are the UKF dynamic models, are derived under grid frames. This paper chooses the velocity plus attitude matching method as the TA matching method and errors of velocity and attitude as observations. The misalignment angle can be estimated by the designed UKF. The simulation results have demonstrated that the polar TA algorithm can be effective in improving the TA accuracy, especially when large misalignment angles occur. (paper)

Multiple scattering of polarized light: comparison of Maxwell theory and radiative transfer theory.

Science.gov (United States)

Voit, Florian; Hohmann, Ansgar; Schäfer, Jan; Kienle, Alwin

2012-04-01

For many research areas in biomedical optics, information about scattering of polarized light in turbid media is of increasing importance. Scattering simulations within this field are mainly performed on the basis of radiative transfer theory. In this study a polarization sensitive Monte Carlo solution of radiative transfer theory is compared to exact Maxwell solutions for all elements of the scattering Müller matrix. Different scatterer volume concentrations are modeled as a multitude of monodisperse nonabsorbing spheres randomly positioned in a cubic simulation volume which is irradiated with monochromatic incident light. For all Müller matrix elements effects due to dependent scattering and multiple scattering are analysed. The results are in overall good agreement between the two methods with deviations related to dependent scattering being prominent for high volume concentrations and high scattering angles.

Dynamic Nuclear Polarization and other magnetic ideas at EPFL.

Science.gov (United States)

Bornet, Aurélien; Milani, Jonas; Wang, Shutao; Mammoli, Daniele; Buratto, Roberto; Salvi, Nicola; Segaw, Takuya F; Vitzthum, Veronika; Miéville, Pascal; Chinthalapalli, Srinivas; Perez-Linde, Angel J; Carnevale, Diego; Jannin, Sami; Caporinia, Marc; Ulzega, Simone; Rey, Martial; Bodenhausen, Geoffrey

2012-01-01

Although nuclear magnetic resonance (NMR) can provide a wealth of information, it often suffers from a lack of sensitivity. Dynamic Nuclear Polarization (DNP) provides a way to increase the polarization and hence the signal intensities in NMR spectra by transferring the favourable electron spin polarization of paramagnetic centres to the surrounding nuclear spins through appropriate microwave irradiation. In our group at EPFL, two complementary DNP techniques are under investigation: the combination of DNP with magic angle spinning at temperatures near 100 K ('MAS-DNP'), and the combination of DNP at 1.2 K with rapid heating followed by the transfer of the sample to a high-resolution magnet ('dissolution DNP'). Recent applications of MAS-DNP to surfaces, as well as new developments of magnetization transfer of (1)H to (13)C at 1.2 K prior to dissolution will illustrate the work performed in our group. A second part of the paper will give an overview of some 'non-enhanced' activities of our laboratory in liquid- and solid-state NMR.

Competitive photocyclization/rearrangement of 4-aryl-1,1-dicyanobutenes controlled by intramolecular charge-transfer interaction. Effect of medium polarity, temperature, pressure, excitation wavelength, and confinement.

Science.gov (United States)

Ito, Tadashi; Nishiuchi, Emi; Fukuhara, Gaku; Inoue, Yoshihisa; Mori, Tadashi

2011-09-01

A series of 4-aryl-1,1-dicyanobutenes (1a-1f) with different substituents were synthesized to control the intramolecular donor-acceptor or charge-transfer (C-T) interactions in the ground state. Photoexcitation of these C-T substrates led to competitive cyclization and rearrangement, the ratio being critically controlled by various environmental factors, such as solvent polarity, temperature and static pressure, and also by excitation wavelength and supramolecular confinement (polyethylene voids). In non-polar solvents, the rearrangement was dominant (>10 : 1) for all examined substrates, while the cyclization was favoured in polar solvents, in particular at low temperatures. Selective excitation at the C-T band further enhanced the cyclization up to >50 : 1 ratios. More importantly, the cyclization/rearrangement ratio was revealed to be a linear function of the C-T transition energy. However, the substrates with a sterically demanding or highly electron-donating substituent failed to give the cyclization product.

Live births after polar body biopsy and frozen-thawed cleavage stage embryo transfer: case report.

Science.gov (United States)

Guimarães, Fernando; Roque, Matheus; Valle, Marcello; Kostolias, Alessandra; Azevedo, Rodrigo A de; Martinhago, Ciro D; Sampaio, Marcos; Geber, Selmo

2016-12-01

Pre-implantation genetic diagnosis (PGD) or screening (PGS) technology, has emerged and developed in the past few years, benefiting couples as it allows the selection and transfer of healthy embryos during IVF treatments. These techniques can be performed in oocytes (polar-body biopsy) or embryos (blastomere or trophectoderm biopsy). In this case report, we describe the first two live births to be published in Brazil after a polar-body (PB) biopsy. In case 1, a 42-year-old was submitted to PB biopsy with PGS due to advanced maternal age and poor ovarian reserve. Five MII oocytes underwent first and second polar body biopsy and four cleavage embryos were cryopreserved. The PGS analysis resulted in two euploid embryos (next generation sequence). A frozen-thawed embryo transfer (FET) was performed after endometrial priming and a healthy baby was delivered after a cesarean section (37 weeks, female, 3390g, 47.5 cm). In case 2, a 40-year old patient with balanced translocation and poor ovarian response was submitted to PB biopsy. Two MII oocytes underwent first and second polar body biopsy and two embryos were cryopreserved in cleavage stage. The analysis resulted in one euploid embryo that was transferred after endometrial priming. A preterm healthy baby (34 weeks, female, 2100g, 40 cm) was delivered via cesarean section. In conclusion, although the blastocyst biopsy is the norm when performing PGS/PGD during IVF treatments, other alternatives (as PB biopsy) should be considered in some specific situations.

Formal Solutions for Polarized Radiative Transfer. II. High-order Methods

Energy Technology Data Exchange (ETDEWEB)

Janett, Gioele; Steiner, Oskar; Belluzzi, Luca, E-mail: gioele.janett@irsol.ch [Istituto Ricerche Solari Locarno (IRSOL), 6605 Locarno-Monti (Switzerland)

2017-08-20

When integrating the radiative transfer equation for polarized light, the necessity of high-order numerical methods is well known. In fact, well-performing high-order formal solvers enable higher accuracy and the use of coarser spatial grids. Aiming to provide a clear comparison between formal solvers, this work presents different high-order numerical schemes and applies the systematic analysis proposed by Janett et al., emphasizing their advantages and drawbacks in terms of order of accuracy, stability, and computational cost.

Variety of Polarized Line Profiles in Interacting Supernovae

Science.gov (United States)

Hoffman, Jennifer L.; Huk, L. N.; Peters, C. L.

2013-01-01

The dense circumstellar material that creates strong emission lines in the spectra of interacting supernovae also gives rise to complex line polarization behavior. Viewed in polarized light, the emission line profiles of these supernovae encode information about the geometrical and optical characteristics of their surrounding circumstellar material (CSM) that is inaccessible by other observational techniques. To facilitate quantitative interpretation of these spectropolarimetric signatures, we have created a large grid of model polarized line profiles using a three-dimensional radiative transfer code that simulates polarization via electron and resonant/fluorescent line scattering. The simulated polarized lines take on an array of profile shapes that vary with viewing angle and CSM properties. We present the major results from the grid and investigate the dependence of polarized line profiles on CSM characteristics including temperature, optical depth, and geometry. These results will allow more straightforward interpretation of polarized line profiles in interacting supernovae than has previously been possible. This research is supported by the National Science Foundation through the AAG program and the XSEDE collaboration, and uses the resources of the Texas Advanced Computing Center.

Joule heating and spin-transfer torque investigated on the atomic scale using a spin-polarized scanning tunneling microscope.

Science.gov (United States)

Krause, S; Herzog, G; Schlenhoff, A; Sonntag, A; Wiesendanger, R

2011-10-28

The influence of a high spin-polarized tunnel current onto the switching behavior of a superparamagnetic nanoisland on a nonmagnetic substrate is investigated by means of spin-polarized scanning tunneling microscopy. A detailed lifetime analysis allows for a quantification of the effective temperature rise of the nanoisland and the modification of the activation energy barrier for magnetization reversal, thereby using the nanoisland as a local thermometer and spin-transfer torque analyzer. Both the Joule heating and spin-transfer torque are found to scale linearly with the tunnel current. The results are compared to experiments performed on lithographically fabricated magneto-tunnel junctions, revealing a very high spin-transfer torque switching efficiency in our experiments.

Polarization transfer between oriented metastable helium atoms and neon atoms. A comparison of even and odd isotopes

Energy Technology Data Exchange (ETDEWEB)

Pepper, D M; Wang, H T.M.

1983-11-01

Collision-induced polarization transfer from optically pumped helium to excited states of neon is studied using various combinations of even and odd isotopes. It is found that, within our experimental accuracy of 10%, the resultant polarization is independent of the isotopic composition of the binary mixture. Possible applications using this mechanism are discussed.

Formal Solutions for Polarized Radiative Transfer. I. The DELO Family

Energy Technology Data Exchange (ETDEWEB)

Janett, Gioele; Carlin, Edgar S.; Steiner, Oskar; Belluzzi, Luca, E-mail: gioele.janett@irsol.ch [Istituto Ricerche Solari Locarno (IRSOL), 6605 Locarno-Monti (Switzerland)

2017-05-10

The discussion regarding the numerical integration of the polarized radiative transfer equation is still open and the comparison between the different numerical schemes proposed by different authors in the past is not fully clear. Aiming at facilitating the comprehension of the advantages and drawbacks of the different formal solvers, this work presents a reference paradigm for their characterization based on the concepts of order of accuracy , stability , and computational cost . Special attention is paid to understand the numerical methods belonging to the Diagonal Element Lambda Operator family, in an attempt to highlight their specificities.

Improper ferroelectric polarization in a perovskite driven by intersite charge transfer and ordering

Science.gov (United States)

Chen, Wei-Tin; Wang, Chin-Wei; Wu, Hung-Cheng; Chou, Fang-Cheng; Yang, Hung-Duen; Simonov, Arkadiy; Senn, M. S.

2018-04-01

It is of great interest to design and make materials in which ferroelectric polarization is coupled to other order parameters such as lattice, magnetic, and electronic instabilities. Such materials will be invaluable in next-generation data storage devices. Recently, remarkable progress has been made in understanding improper ferroelectric coupling mechanisms that arise from lattice and magnetic instabilities. However, although theoretically predicted, a compact lattice coupling between electronic and ferroelectric (polar) instabilities has yet to be realized. Here we report detailed crystallographic studies of a perovskite HgAMn3A'Mn4BO12 that is found to exhibit a polar ground state on account of such couplings that arise from charge and orbital ordering on both the A'- and B-sites, which are themselves driven by a highly unusual MnA '-MnB intersite charge transfer. The inherent coupling of polar, charge, orbital, and hence magnetic degrees of freedom make this a system of great fundamental interest, and demonstrating ferroelectric switching in this and a host of recently reported hybrid improper ferroelectrics remains a substantial challenge.

The evolution of tensor polarization

International Nuclear Information System (INIS)

Huang, H.; Lee, S.Y.; Ratner, L.

1993-01-01

By using the equation of motion for the vector polarization, the spin transfer matrix for spin tensor polarization, the spin transfer matrix for spin tensor polarization is derived. The evolution equation for the tensor polarization is studied in the presence of an isolate spin resonance and in the presence of a spin rotor, or snake

Spin Transfer in Inclusive Λ0 Production by Transversely Polarized Protons at 200GeV/c

International Nuclear Information System (INIS)

Grosnick, D.P.; Hill, D.A.; Laghai, M.; Lopiano, D.; Ohashi, Y.; Spinka, H.; Stanek, R.W.; Underwood, D.G.; Yokosawa, A.; Bystricky, J.; Lehar, F.; Lesquen, A. de; Rossum, L. van; Cossairt, J.D.; Read, A.L.; Iwatani, K.; Belikov, N.I.; Derevschikov, A.A.; Grachov, O.A.; Matulenko, Y.A.; Meschanin, A.P.; Nurushev, S.B.; Patalakha, D.I.; Rykov, V.L.; Solovyanov, V.L.; Vasiliev, A.N.; Akchurin, N.; Onel, Y.; Maki, T.; Enyo, H.; Funahashi, H.; Goto, Y.; Iijima, T.; Imai, K.; Itow, Y.; Makino, S.; Masaike, A.; Miyake, K.; Nagamine, T.; Saito, N.; Yamashita, S.; Takashima, R.; Takeutchi, F.; Kuroda, K.; Michalowicz, A.; Rappazzo, G.F.; Salvato, G.; Luehring, F.C.; Miller, D.H.; Tamura, N.; Yoshida, T.; Adams, D.L.; Bonner, B.E.; Corcoran, M.D.; Cranshaw, J.; Nessi-Tedaldi, F.; Nessi, M.; Nguyen, C.; Roberts, J.B.; Skeens, J.; White, J.L.; Bravar, A.

1997-01-01

Surprisingly large polarizations in hyperon production by unpolarized protons have been known for a long time. The spin dynamics of the production process can be further investigated with polarized beams. Recently, a negative asymmetry A N was found in inclusive Λ 0 production with a 200GeV/c transversely polarized proton beam. The depolarization D NN in p↑+p→Λ 0 +X has been measured with the same beam over a wide x F range and at moderate p T . D NN reaches positive values of about 30% at high x F and p T ∼1.0GeV/c . This result shows a sizable spin transfer from the incident polarized proton to the outgoing Λ 0 . copyright 1997 The American Physical Society

Considering polarization in MODIS-based cloud property retrievals by using a vector radiative transfer code

International Nuclear Information System (INIS)

Yi, Bingqi; Huang, Xin; Yang, Ping; Baum, Bryan A.; Kattawar, George W.

2014-01-01

In this study, a full-vector, adding–doubling radiative transfer model is used to investigate the influence of the polarization state on cloud property retrievals from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations. Two sets of lookup tables (LUTs) are developed for the retrieval purposes, both of which provide water cloud and ice cloud reflectivity functions at two wavelengths in various sun-satellite viewing geometries. However, only one of the LUTs considers polarization. The MODIS reflectivity observations at 0.65 μm (band 1) and 2.13 μm (band 7) are used to infer the cloud optical thickness and particle effective diameter, respectively. Results indicate that the retrievals for both water cloud and ice cloud show considerable sensitivity to polarization. The retrieved water and ice cloud effective diameter and optical thickness differences can vary by as much as ±15% due to polarization state considerations. In particular, the polarization state has more influence on completely smooth ice particles than on severely roughened ice particles. - Highlights: • Impact of polarization on satellite-based retrieval of water/ice cloud properties is studied. • Inclusion of polarization can change water/ice optical thickness and effective diameter values by up to ±15%. • Influence of polarization on cloud property retrievals depends on sun-satellite viewing geometries

When measured spin polarization is not spin polarization

International Nuclear Information System (INIS)

Dowben, P A; Wu Ning; Binek, Christian

2011-01-01

Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO 2 and Cr 2 O 3 illustrate some of the complications which hinders comparisons of spin polarization values. (viewpoint)

The Physics of Polarization

Science.gov (United States)

Landi Degl'Innocenti, Egidio

2015-10-01

The introductory lecture that has been delivered at this Symposium is a condensed version of an extended course held by the author at the XII Canary Island Winter School from November 13 to November 21, 2000. The full series of lectures can be found in Landi Degl'Innocenti (2002). The original reference is organized in 20 Sections that are here itemized: 1. Introduction, 2. Description of polarized radiation, 3. Polarization and optical devices: Jones calculus and Muller matrices, 4. The Fresnel equations, 5. Dichroism and anomalous dispersion, 6. Polarization in everyday life, 7. Polarization due to radiating charges, 8. The linear antenna, 9. Thomson scattering, 10. Rayleigh scattering, 11. A digression on Mie scattering, 12. Bremsstrahlung radiation, 13. Cyclotron radiation, 14. Synchrotron radiation, 15. Polarization in spectral lines, 16. Density matrix and atomic polarization, 17. Radiative transfer and statistical equilibrium equations, 18. The amplification condition in polarized radiative transfer, and 19. Coupling radiative transfer and statistical equilibrium equations.

RADIATIVE TRANSFER MODELING OF THE ENIGMATIC SCATTERING POLARIZATION IN THE SOLAR Na i D{sub 1} LINE

Energy Technology Data Exchange (ETDEWEB)

Belluzzi, Luca [Istituto Ricerche Solari Locarno, CH-6605 Locarno Monti (Switzerland); Bueno, Javier Trujillo [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Degl’Innocenti, Egidio Landi [Dipartimento di Fisica e Astronomia, Università di Firenze, I-50125 Firenze (Italy)

2015-12-01

The modeling of the peculiar scattering polarization signals observed in some diagnostically important solar resonance lines requires the consideration of the detailed spectral structure of the incident radiation field as well as the possibility of ground level polarization, along with the atom's hyperfine structure and quantum interference between hyperfine F-levels pertaining either to the same fine structure J-level, or to different J-levels of the same term. Here we present a theoretical and numerical approach suitable for solving this complex non-LTE radiative transfer problem. This approach is based on the density-matrix metalevel theory (where each level is viewed as a continuous distribution of sublevels) and on accurate formal solvers of the transfer equations and efficient iterative methods. We show an application to the D-lines of Na i, with emphasis on the enigmatic D{sub 1} line, pointing out the observable signatures of the various physical mechanisms considered. We demonstrate that the linear polarization observed in the core of the D{sub 1} line may be explained by the effect that one gets when the detailed spectral structure of the anisotropic radiation responsible for the optical pumping is taken into account. This physical ingredient is capable of introducing significant scattering polarization in the core of the Na i D{sub 1} line without the need for ground-level polarization.

BACKWARD AND FORWARD MONTE CARLO METHOD IN POLARIZED RADIATIVE TRANSFER

Energy Technology Data Exchange (ETDEWEB)

Yong, Huang; Guo-Dong, Shi; Ke-Yong, Zhu, E-mail: huangy_zl@263.net [School of Aeronautical Science and Engineering, Beihang University, Beijing 100191 (China)

2016-03-20

In general, the Stocks vector cannot be calculated in reverse in the vector radiative transfer. This paper presents a novel backward and forward Monte Carlo simulation strategy to study the vector radiative transfer in the participated medium. A backward Monte Carlo process is used to calculate the ray trajectory and the endpoint of the ray. The Stocks vector is carried out by a forward Monte Carlo process. A one-dimensional graded index semi-transparent medium was presented as the physical model and the thermal emission consideration of polarization was studied in the medium. The solution process to non-scattering, isotropic scattering, and the anisotropic scattering medium, respectively, is discussed. The influence of the optical thickness and albedo on the Stocks vector are studied. The results show that the U, V-components of the apparent Stocks vector are very small, but the Q-component of the apparent Stocks vector is relatively larger, which cannot be ignored.

Polarization-preserving holey fibers

DEFF Research Database (Denmark)

Broeng, Jes; Mogilevtsev, Dmitri; Libori, Stig E. Barkou

2001-01-01

In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization......In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization...

Imaging and modeling of collagen architecture in living tissue with polarized light transfer (Conference Presentation)

Science.gov (United States)

Ramella-Roman, Jessica C.; Stoff, Susan; Chue-Sang, Joseph; Bai, Yuqiang

2016-03-01

The extra-cellular space in connective tissue of animals and humans alike is comprised in large part of collagen. Monitoring of collagen arrangement and cross-linking has been utilized to diagnose a variety of medical conditions and guide surgical intervention. For example, collagen monitoring is useful in the assessment and treatment of cervical cancer, skin cancer, myocardial infarction, and non-arteritic anterior ischemic optic neuropathy. We have developed a suite of tools and models based on polarized light transfer for the assessment of collagen presence, cross-linking, and orientation in living tissue. Here we will present some example of such approach applied to the human cervix. We will illustrate a novel Mueller Matrix (MM) imaging system for the study of cervical tissue; furthermore we will show how our model of polarized light transfer through cervical tissue compares to the experimental findings. Finally we will show validation of the methodology through histological results and Second Harmonic imaging microscopy.

A new instrumental set-up for polarized neutron scattering experiments

International Nuclear Information System (INIS)

Schmidt, Wolfgang; Ohl, Michael

2005-01-01

Neutron scattering with polarization analysis is a powerful tool to determine magnetic structures and excitations. A common setup is to mount the sample at the center of a Helmholtz-type coil which can provide a magnetic field of any direction at the sample position and also a guide field along the neutron flight paths around the sample. Recent experiments showed quite a high demand for measurements at low momentum transfers. For the corresponding low scattering angles air scattering gives rise to a very large background. For this reason we have extended the standard setup to a combination of a large vacuum tank surrounded by electrical coils. The vacuum tank eliminates the air scattering and we can use the polarization analysis down to the lowest accessible momentum transfers. The coils themselves also show some new features: In contrary to the classic (symmetric) coil distribution we use an asymmetric setup which gives the advantage of a larger scattering window. Due to a more sophisticated current distribution this modified coil arrangement needs not to be rotated for different scattering conditions. The whole set-up will soon be available at IN12, a cold neutrons three-axis spectrometer operated by FZ Juelich in collaboration with CEA Grenoble as a CRG-B instrument at the Institut Laue Langevin in Grenoble

Polarization transfer in the 3H(rvec p,rvec n)3He reaction and the 0- level in 4He

International Nuclear Information System (INIS)

Walston, J.R.; Gould, C.R.; Haase, D.G.; Raichle, B.W.; Seely, M.L.; Walston, J.R.; Keith, C.D.; Gould, C.R.; Haase, D.G.; Raichle, B.W.; Seely, M.L.; Tornow, W.; Wilburn, W.S.; Keith, C.D.; Tornow, W.; Wilburn, W.S.; Hoffmann, G.W.; Penttilae, S.I.

1998-01-01

Longitudinal polarization-transfer coefficients for the 3 H(rvec p,rvec n) 3 He reaction have been measured at zero degrees for proton energies of 1.3 endash 2.8 MeV. The results show a striking resonance behavior for energies corresponding to excitation of the 0 - level in 4 He at 21.0 MeV. In agreement with R-matrix calculations, the value approaches unity at 1.52 MeV, the peak of the resonance. Near this same energy, at 1.62 MeV, the transverse polarization-transfer coefficient was measured to be consistent with zero. copyright 1998 The American Physical Society

A MULTIPLE SCATTERING POLARIZED RADIATIVE TRANSFER MODEL: APPLICATION TO HD 189733b

Energy Technology Data Exchange (ETDEWEB)

Kopparla, Pushkar; Yung, Yuk L. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA (United States); Natraj, Vijay; Swain, Mark R. [Jet Propulsion Laboratory (NASA-JPL), Pasadena, CA (United States); Zhang, Xi [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ (United States); Wiktorowicz, Sloane J., E-mail: pkk@gps.caltech.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States)

2016-01-20

We present a multiple scattering vector radiative transfer model that produces disk integrated, full phase polarized light curves for reflected light from an exoplanetary atmosphere. We validate our model against results from published analytical and computational models and discuss a small number of cases relevant to the existing and possible near-future observations of the exoplanet HD 189733b. HD 189733b is arguably the most well observed exoplanet to date and the only exoplanet to be observed in polarized light, yet it is debated if the planet’s atmosphere is cloudy or clear. We model reflected light from clear atmospheres with Rayleigh scattering, and cloudy or hazy atmospheres with Mie and fractal aggregate particles. We show that clear and cloudy atmospheres have large differences in polarized light as compared to simple flux measurements, though existing observations are insufficient to make this distinction. Futhermore, we show that atmospheres that are spatially inhomogeneous, such as being partially covered by clouds or hazes, exhibit larger contrasts in polarized light when compared to clear atmospheres. This effect can potentially be used to identify patchy clouds in exoplanets. Given a set of full phase polarimetric measurements, this model can constrain the geometric albedo, properties of scattering particles in the atmosphere, and the longitude of the ascending node of the orbit. The model is used to interpret new polarimetric observations of HD 189733b in a companion paper.

On the intramolecular proton transfer of 3-hydroxyflavone in the first singlet excited state: A theoretical study

International Nuclear Information System (INIS)

Casadesus, Ricard; Vendrell, Oriol; Moreno, Miquel; Lluch, Jose M.; Morokuma, Keiji

2006-01-01

The intramolecular proton-transfer reaction in 3-hydroxyflavone (3HF) is theoretically studied both in the ground (S 0 ) and first singlet excited (S 1 ) electronic states. In S 0 the proton-transfer reaction is shown to be quite unfavorable at the DFT (B3LYP) level. However, the back proton transfer is found to be a feasible process with a small energy barrier, both results being in qualitative agreement with known experimental facts. Different theoretical levels are considered and compared for S 1 . The ab initio configuration interaction singles (CIS) method overestimates the energy of S 1 and give too high energy barriers for the proton-transfer reaction. The complete active space SCF (CASSCF) method gives a more reasonable value but the inclusion of the dynamical correlation through second-order perturbation theory (CASPT2) upon CASSCF geometries or the use of the time-dependent DFT (TDDFT) method upon CIS geometries gives a barrierless process. Optimization of geometries (minima and transition-state structures) at the TDDFT level leads to a small but non-negligible energy barrier for the proton-transfer reaction in S 1 and global energies that fit quite well with the known experimental (spectroscopic and femtochemistry) data. Finally the effect of a polar environment is analyzed through a continuum model, which gives only a small difference from the previous gas-phase results. This points out that the remarkable changes in the photochemistry of 3HF observed experimentally are not to be solely attributed to the polarity of the surrounding media

On the intramolecular proton transfer of 3-hydroxyflavone in the first singlet excited state: A theoretical study

Energy Technology Data Exchange (ETDEWEB)

Casadesus, Ricard [Departament de Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA 30322 (United States); Vendrell, Oriol [Departament de Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Moreno, Miquel [Departament de Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)], E-mail: mmf@klingon.uab.es; Lluch, Jose M. [Departament de Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Morokuma, Keiji [Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA 30322 (United States)

2006-06-20

The intramolecular proton-transfer reaction in 3-hydroxyflavone (3HF) is theoretically studied both in the ground (S{sub 0}) and first singlet excited (S{sub 1}) electronic states. In S{sub 0} the proton-transfer reaction is shown to be quite unfavorable at the DFT (B3LYP) level. However, the back proton transfer is found to be a feasible process with a small energy barrier, both results being in qualitative agreement with known experimental facts. Different theoretical levels are considered and compared for S{sub 1}. The ab initio configuration interaction singles (CIS) method overestimates the energy of S{sub 1} and give too high energy barriers for the proton-transfer reaction. The complete active space SCF (CASSCF) method gives a more reasonable value but the inclusion of the dynamical correlation through second-order perturbation theory (CASPT2) upon CASSCF geometries or the use of the time-dependent DFT (TDDFT) method upon CIS geometries gives a barrierless process. Optimization of geometries (minima and transition-state structures) at the TDDFT level leads to a small but non-negligible energy barrier for the proton-transfer reaction in S{sub 1} and global energies that fit quite well with the known experimental (spectroscopic and femtochemistry) data. Finally the effect of a polar environment is analyzed through a continuum model, which gives only a small difference from the previous gas-phase results. This points out that the remarkable changes in the photochemistry of 3HF observed experimentally are not to be solely attributed to the polarity of the surrounding media.

Neutron polarization in polarized 3He targets

International Nuclear Information System (INIS)

Friar, J.L.; Gibson, B.F.; Payne, G.L.; Bernstein, A.M.; Chupp, T.E.

1990-01-01

Simple formulas for the neutron and proton polarizations in polarized 3 He targets are derived assuming (1) quasielastic final states; (2) no final-state interactions; (3) no meson-exchange currents; (4) large momentum transfers; (5) factorizability of 3 He SU(4) response-function components. Numerical results from a wide variety of bound-state solutions of the Faddeev equations are presented. It is found that this simple model predicts the polarization of neutrons in a fully polarized 3 He target to be 87%, while protons should have a slight residual polarization of -2.7%. Numerical studies show that this model works very well for quasielastic electron scattering

Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTES

Science.gov (United States)

Stolker, T.; Min, M.; Stam, D. M.; Mollière, P.; Dominik, C.; Waters, L. B. F. M.

2017-11-01

Context. Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly detectable with the newest generation of high-contrast imaging instruments. Aims: We aim to investigate the effect of latitudinal and longitudinal cloud variations, circumplanetary disks, atmospheric oblateness, and cloud particle properties on the integrated degree and direction of polarization in the near-infrared. We want to understand how 3D atmospheric asymmetries affect the polarization signal in order to assess the potential of infrared polarimetry for direct imaging observations of planetary-mass companions. Methods: We have developed a three-dimensional Monte Carlo radiative transfer code (ARTES) for scattered light simulations in (exo)planetary atmospheres. The code is applicable to calculations of reflected light and thermal radiation in a spherical grid with a parameterized distribution of gas, clouds, hazes, and circumplanetary material. A gray atmosphere approximation is used for the thermal structure. Results: The disk-integrated degree of polarization of a horizontally-inhomogeneous atmosphere is maximal when the planet is flattened, the optical thickness of the equatorial clouds is large compared to the polar clouds, and the clouds are located at high altitude. For a flattened planet, the integrated polarization can both increase or decrease with respect to a spherical planet which depends on the horizontal distribution and optical thickness of the clouds. The direction of polarization can be either parallel or perpendicular to the projected direction of the rotation axis when clouds are zonally distributed. Rayleigh scattering by submicron-sized cloud particles will maximize the polarimetric signal whereas the integrated degree of polarization is significantly reduced with micron

Wideband metamaterial array with polarization-independent and wide incident angle for harvesting ambient electromagnetic energy and wireless power transfer

Science.gov (United States)

Zhong, Hui-Teng; Yang, Xue-Xia; Song, Xing-Tang; Guo, Zhen-Yue; Yu, Fan

2017-11-01

In this work, we introduced the design, demonstration, and discussion of a wideband metamaterial array with polarization-independent and wide-angle for harvesting ambient electromagnetic (EM) energy and wireless power transfer. The array consists of unit cells with one square ring and four metal bars. In comparison to the published metamaterial arrays for harvesting EM energy or wireless transfer, this design had the wide operation bandwidth with the HPBW (Half Power Band Width) of 110% (6.2 GHz-21.4 GHz), which overcomes the narrow-band operation induced by the resonance characteristic of the metamaterial. On the normal incidence, the simulated maximum harvesting efficiency was 96% and the HPBW was 110% for the random polarization wave. As the incident angle increases to 45°, the maximum efficiency remained higher than 88% and the HPBW remained higher than 83% for the random polarization wave. Furthermore, the experimental verification of the designed metamaterial array was conducted, and the measured results were in reasonable agreement with the simulated ones.

Development of high-polarization Fe/Ge neutron polarizing supermirror: Possibility of fine-tuning of scattering length density in ion beam sputtering

Science.gov (United States)

Maruyama, R.; Yamazaki, D.; Akutsu, K.; Hanashima, T.; Miyata, N.; Aoki, H.; Takeda, M.; Soyama, K.

2018-04-01

The multilayer structure of Fe/Si and Fe/Ge systems fabricated by ion beam sputtering (IBS) was investigated using X-ray and polarized neutron reflectivity measurements and scanning transmission electron microscopy with energy-dispersive X-ray analysis. The obtained result revealed that the incorporation of sputtering gas particles (Ar) in the Ge layer gives rise to a marked reduction in the neutron scattering length density (SLD) and contributes to the SLD contrast between the Fe and Ge layers almost vanishing for spin-down neutrons. Bundesmann et al. (2015) have shown that the implantation of primary Ar ions backscattered at the target is responsible for the incorporation of Ar particles and that the fraction increases with increasing ion incidence angle and increasing polar emission angle. This leads to a possibility of fine-tuning of the SLD for the IBS, which is required to realize a high polarization efficiency of a neutron polarizing supermirror. Fe/Ge polarizing supermirror with m = 5 fabricated under the same condition showed a spin-up reflectivity of 0.70 at the critical momentum transfer. The polarization was higher than 0.985 for the qz range where the correction for the polarization inefficiencies of the beamline works properly. The result of the polarized neutron reflectivity measurement suggests that the "magnetically-dead" layers formed at both sides of the Fe layer, together with the SLD contrast, play a critical role in determining the polarization performance of a polarizing supermirror.

Polarization of the sigma minus hyperon produced by a polarized neutral particle beam

International Nuclear Information System (INIS)

Nguyen, A.N.

1992-01-01

A spin transfer technique has been tried in an attempt to produce a beam of polarized hyperons. The method makes use of a two-stage targeting scheme where unpolarized protons from Fermilab's Tevatron incident on target number one (Cu) at production angles of ±2.0 mrad would produce a beam of particles containing polarized Λs and Ξs as well as neutrons and Ks. This secondary beam would then be swept magnetically to retain only neutral particles and brought to bear on target number two (Cu) at 0.0 mrad, producing a tertiary beam of hyperons. The polarization of some 1.3 millions reconstructed Σ - → nπ - events in this tertiary beam (the Σ - having been produced in the inclusive reaction neutrals + Cu → Σ - + X) has been measured at average Σ - momenta 320 GeV/c (1.14 millions events) and 410 GeV/c (135,000 events) and found to be |P| = 3.9 ± 3.2 ± 1.8% and |P| = 13.9 ± 8.1 ± 2.0% respectively, where the first uncertainty is statistical and the second systematic. These polarizations are small and consistent with zero, and preclude a meaningful measurement of the Σ - magnetic moment by the spin precession method. The sign of the polarizations at the target is ambiguous, giving rise to two possible different solutions for the magnetic moment-one of two possible different solutions for the magnetic moment-one of which distinctly disagrees with the world average value for the moment. However, this solution fits the data slightly better than the other. This inconsistency would not exist if the polarization is, in fact, zero

H- ion current from a polarized vapor target

International Nuclear Information System (INIS)

Cornelius, W.D.

1984-01-01

A method of determining the polarization transferred to hydrogen atoms in charge-exchange reactions is outlined. The method also provides a means of determining target polarizations once the polarization transfer function is known

Effect of polarized radiative transfer on the Hanle magnetic field determination in prominences: Analysis of hydrogen H alpha line observations at Pic-du-Midi

Science.gov (United States)

Bommier, V.; Deglinnocenti, E. L.; Leroy, J. L.; Sahal-Brechot, S.

1985-01-01

The linear polarization of the Hydrogen H alpha line of prominences has been computed, taking into account the effect of a magnetic field (Hanle effect), of the radiative transfer in the prominence, and of the depolarization due to collisions with the surrounding electrons and protons. The corresponding formalisms are developed in a forthcoming series of papers. In this paper, the main features of the computation method are summarized. The results of computation have been used for interpretation in terms of magnetic field vector measurements from H alpha polarimetric observations in prominences performed at Pic-du-Midi coronagraph-polarimeter. Simultaneous observations in one optically thin line (He I D(3)) and one optically thick line (H alpha) give an opportunity for solving the ambiguity on the field vector determination.

Transient-field strength measurements for 52Cr traversing Fe hosts at high velocity and polarization transfer mechanisms

International Nuclear Information System (INIS)

Stuchbery, A.E.; Doran, C.E.; Byrne, A.P.; Bolotin, H.H.; Dracoulis, G.D.

1986-12-01

Transient-field strengths were measured for 52 Cr ions traversing polarized Fe hosts at velocities up to 12v>=o (v>=o = c/137 = Bohr velocity). The results are compared with predictions of various transient field parametrizations and discussed in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving Cr ions. The g-factor of the first 2 + state of 52 Cr was also measured by the transient field technique and found to be in accord with shell-model calculations

Photoinduced electron transfer in covalent ruthenium-anthraquinone dyads: relative importance of driving-force, solvent polarity, and donor-bridge energy gap.

Science.gov (United States)

Hankache, Jihane; Wenger, Oliver S

2012-02-28

Four rigid rod-like molecules comprised of a Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine) photosensitizer, a 9,10-anthraquinone electron acceptor, and a molecular bridge connecting the two redox partners were synthesized and investigated by optical spectroscopic and electrochemical means. An attempt was made to assess the relative importance of driving-force, solvent polarity, and bridge variation on the rates of photoinduced electron transfer in these molecules. Expectedly, introduction of tert-butyl substituents in the bipyridine ligands of the ruthenium complex and a change in solvent from dichloromethane to acetonitrile lead to a significant acceleration of charge transfer rates. In dichloromethane, photoinduced electron transfer is not competitive with the inherent excited-state deactivation processes of the photosensitizer. In acetonitrile, an increase in driving-force by 0.2 eV through attachment of tert-butyl substituents to the bpy ancillary ligands causes an increase in electron transfer rates by an order of magnitude. Replacement of a p-xylene bridge by a p-dimethoxybenzene spacer entails an acceleration of charge transfer rates by a factor of 3.5. In the dyads from this study, the relative order of importance of individual influences on electron transfer rates is therefore as follows: solvent polarity ≥ driving-force > donor-bridge energy gap.

Inequality and redistribution behavior in a give-or-take game

Science.gov (United States)

Bechtel, Michael M.; Scheve, Kenneth F.

2018-01-01

Political polarization and extremism are widely thought to be driven by the surge in economic inequality in many countries around the world. Understanding why inequality persists depends on knowing the causal effect of inequality on individual behavior. We study how inequality affects redistribution behavior in a randomized “give-or-take” experiment that created equality, advantageous inequality, or disadvantageous inequality between two individuals before offering one of them the opportunity to either take from or give to the other. We estimate the causal effect of inequality in representative samples of German and American citizens (n = 4,966) and establish two main findings. First, individuals imperfectly equalize payoffs: On average, respondents transfer 12% of the available endowments to realize more equal wealth distributions. This means that respondents tolerate a considerable degree of inequality even in a setting in which there are no costs to redistribution. Second, redistribution behavior in response to disadvantageous and advantageous inequality is largely asymmetric: Individuals who take from those who are richer do not also tend to give to those who are poorer, and individuals who give to those who are poorer do not tend to take from those who are richer. These behavioral redistribution types correlate in meaningful ways with support for heavy taxes on the rich and the provision of welfare benefits for the poor. Consequently, it seems difficult to construct a majority coalition willing to back the type of government interventions needed to counter rising inequality. PMID:29555734

Nuclear polarization potential due to particle transfer in heavy-ion collisions

International Nuclear Information System (INIS)

Landowne, S.; Dasso, C.H.; Winther, A.; Pollarolo, G.

1986-01-01

The effective interaction which determines the elastic scattering of heavy composite systems consists of a ''bare'' real potential V, noramally identified with the folding model, a renormalization term or ''polarization potential'' ΔV and an imaginary ''absorptive potential'' iW. The latter contributions originate from the couplings to intrinsic degrees of freedom. While iW is a conspicuous feature of all optical model analyses, the related term ΔV has received relatively little attention until recently. The microscopic structure of ΔV + iW is examined using second-order semi-classical perturbation theory. Focus is on the long-range part of ΔV which is governed by single-particle transfer reactions between the colliding systems

Nuclear polarization potential due to particle transfer in heavy-ion collisions

International Nuclear Information System (INIS)

Landowne, S.; Dasso, C.H.; Winther, A.; Pollarolo, G.

1986-01-01

The effective interaction which determines the elastic scattering of heavy composite systems consists of a bare real potential V, normally identified with the folding model, a renormalization term or polarization potential ΔV and an imaginary absorptive potential iW. The latter contributions originate from the couplings to intrinsic degrees of freedom. While iW is a conspicuous feature of all optical model analyses, the related term ΔV has received relatively little attention until recently. Here the authors examine the microscopic structure of ΔV + IW using second-order semi-classical perturbation theory. In particular, they focus on the long-range part of ΔV which is governed by single-particle transfer reactions between the colliding systems

Study of nuclear isovector spin responses from polarization transfer in (p,n) reactions at intermediate energies

International Nuclear Information System (INIS)

Wakasa, Tomotsugu

1997-01-01

We have measured a complete set of polarization transfer observables has been measured for quasi-free (p vector, n vector) reactions on 2 H, 6 Li, 12 C, 40 Ca, and 208 Pb at a bombarding energy of 346MeV and a laboratory scattering angle of 22deg (q=1.7 fm -1 ). The polarization transfer observables for all five targets are remarkably similar. These polarization observables yield separated spin-longitudinal (σ·q) and spin-transverse (σxq) nuclear responses. These results are compared to the spin-transverse responses measured in deep-inelastic electron scattering as well as to nuclear responses based on the random phase approximation. Such a comparison reveals an enhancement in the (p vector, n vector) spin-transverse channel, which masks the effect of pionic correlations in the response ratio. Second, the double differential cross sections at θ lab between 0deg and 12.3deg and the polarization transfer D NN at 0deg for the 90 Zr(p,n) reaction are measured at a bombarding energy of 295MeV. The Gamow-Teller(GT) strength B(GT) in the continuum deduced from the L=0 cross section is compared both with the perturbative calculation by Bertsch and Hamamoto and with the second-order random phase approximation calculation by Drozdz et al. The sum of B(GT) values up to 50MeV excitation becomes S β- =28.0±1.6 after subtracting the contribution of the isovector spin-monopole strength. This S β- value of 28.0±1.6 corresponds to about (93±5)% of the minimum value of the sum-rule 3(N-Z)=30. Last, first measurements of D NN (0deg) for (p vector, n vector) reactions at 295MeV yield large negative values up to 50MeV excitation for the 6 Li, 11 B, 12 C, 13 C(p vector, n vector) reactions. DWIA calculations using the Franey and Love (FL) 270MeV interaction reproduce differential cross sections and D NN (0deg) values, while the FL 325MeV interaction yield D NN (0deg) values less negative than the experimental values. (J.P.N.)

Matrix formulations of radiative transfer including the polarization effect in a coupled atmosphere-ocean system

International Nuclear Information System (INIS)

Ota, Yoshifumi; Higurashi, Akiko; Nakajima, Teruyuki; Yokota, Tatsuya

2010-01-01

A vector radiative transfer model has been developed for a coupled atmosphere-ocean system. The radiative transfer scheme is based on the discrete ordinate and matrix operator methods. The reflection/transmission matrices and source vectors are obtained for each atmospheric or oceanic layer through the discrete ordinate solution. The vertically inhomogeneous system is constructed using the matrix operator method, which combines the radiative interaction between the layers. This radiative transfer scheme is flexible for a vertically inhomogeneous system including the oceanic layers as well as the ocean surface. Compared with the benchmark results, the computational error attributable to the radiative transfer scheme has been less than 0.1% in the case of eight discrete ordinate directions. Furthermore, increasing the number of discrete ordinate directions has produced computations with higher accuracy. Based on our radiative transfer scheme, simulations of sun glint radiation have been presented for wavelengths of 670 nm and 1.6 μm. Results of simulations have shown reasonable characteristics of the sun glint radiation such as the strongly peaked, but slightly smoothed radiation by the rough ocean surface and depolarization through multiple scattering by the aerosol-loaded atmosphere. The radiative transfer scheme of this paper has been implemented to the numerical model named Pstar as one of the OpenCLASTR/STAR radiative transfer code systems, which are widely applied to many radiative transfer problems, including the polarization effect.

Measurement of Tensor Polarization in Elastic Electron-Deuteron Scattering at Large Momentum Transfer

International Nuclear Information System (INIS)

David Abbott; Abdellah Ahmidouch; Heinz Anklin; Francois Arvieux; Jacques Ball; Beedoe, S.; Elizabeth Beise; Louis Bimbot; Werner Boeglin; Herbert Breuer; Roger Carlini; Nicholas Chant; Samuel Danagoulian; Dow, K.; Jean-Eric Ducret; James Dunne; Lars Ewell; Laurent Eyraud; Christophe Furget; Michel Garcon; Ronald Gilman; Charles Glashausser; Paul Gueye; Kenneth Gustafsson; Kawtar Hafidi; Adrian Honegger; Juerg Jourdan; Serge Kox; Gerfried Kumbartzki; Lu, L.; Allison Lung; David Mack; Pete Markowitz; Justin McIntyre; David Meekins; Fernand Merchez; Joseph Mitchell; Mohring, R.; Sekazi Mtingwa; Hamlet Mkrtchyan; David Pitz; Liming Qin; Ronald Ransome; Jean-Sebastien Real; Philip Roos; Paul Rutt; Reyad Sawafta; Samuel Stepanyan; Raphael Tieulent; Egle Tomasi-Gustafsson; William Turchinetz; Kelley Vansyoc; Jochen Volmer; Eric Voutier; William Vulcan; Claude Williamson; Stephen Wood; Chen Yan; Jie Zhao; Wenxia Zhao

2000-01-01

Tensor polarization observables (t20, t21 and t22) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c) 2 . The experiment was performed at the Jefferson Laboratory in Hall C using the electron HMS Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q 2 the deuteron charge form factors G C and G Q . They are in good agreement with relativistic calculations and disagree with pQCD predictions

Polarization transfer in elastic p-d scattering at E sub. rho. = 22. 7 MeV

Energy Technology Data Exchange (ETDEWEB)

Gruebler, W.; Clajus, M.; Egun, P.M.; Hautle, P.; Weber, A. (Eidgenoessische Technische Hochschule, Zurich (CH). Inst. fuer Mittelenergiephysik); Schmelzbach, P.A. (Paul Scherrer Inst. (PSI), Villigen (CH)); Slaus, I. (Institut Ruder Boskovic, Zagreb. (YU)); Vuaridel, B. (Michigan Univ., Ann Arbor, MI (US)); Sperisen, F. (Indiana Univ. Cyclotron Facility, Bloomington, IN (US)); Kretschmer, W.; Karschnick, R.O.; Rauscher, A.; Weidmann, R.; Walter, T. (Erlangen-Nuernberg Univ., Erlangen (DE). Physikalisches Inst.); Bruno, M.; Cannata, F.; d' Agostino, M. (Istituto Nazionale di Fisica Nucleare, Bologna (IT))

1990-11-15

The proton-deuteron elastic scattering has been investigated at E{sub p}=22.7 MeV by comparison of rigorous Faddeev calculations with experimental results. From the calculations it was found that polarization transfer coefficients are more sensitive to details of the nucleon-nucleon potentials than the analyzing powers. Therefore we measured the proton to proton transfer coefficients K{sup y'}{sub y} and K{sup x'}{sub z}. The observable most sensitive to the tensor force is K{sup y'}{sub y}. The angular distributions of K{sup y'}{sub y} and, to a smaller extent, K{sup x'}{sub z} clearly favour the Bonn A potential.

Solvent polarity scale on the fluorescence spectra of a dansyl monomer copolymerizable in aqueous media

Science.gov (United States)

Ren, Biye; Gao, Feng; Tong, Zhen; Yan, Yu

1999-06-01

A copolymerizable fluorescent monomer N-[2-[[[5-(N,N-dimethylamino)-1-naphthalenyl]sulfonyl]-amino]ethyl]-2-propenamide (DANSAEP) was synthesized, which exhibits dual fluorescence due to the twisted intramolecular charge transfer in the excited state. The emission maximum λem shifts from 463.3 nm in n-hexane to 530.0 nm in water, showing solvent polarity dependence. The relations between λem and the conventional solvent polarity parameters ET(30) or Z are linear, dividing solvents into protic and aprotic groups. Kamlet's linear solvation energy relationship gives a good description for λem as a solvent polarity scale. The increment of dipole moment Δ μ at the excited state was estimated as 5.09 D with the solvatochromic analysis.

Polarization Measurements in High-Energy Deuteron Photodisintegration

International Nuclear Information System (INIS)

Adam Sarty; Andrei Afanasev; Arunava Saha; Bogdan Wojtsekhowski; Brendan Fox; Chang, C.; Cathleen Jones; Charles Glashausser; Charles Perdrisat; Cornelis De Jager; Cornelis De Jager; Cornelis de Jager; Crovelli, D.; Daniel Simon; David Meekins; Demetrius Margaziotis; Dipangkar Dutta; Edgar Kooijman; Edward Brash; Edward Kinney; Elaine Schulte; Eugene Chudakov; Feng Xiong; Franco Garibaldi; Garth Huber; Gerfried Kumbartzki; Guido Urciuoli; Haiyan Gao; James Kelly; Javier Gomez; Jens-Ole Hansen; Jian-Ping Chen; John Calarco; John LeRose; Jordan Hovdebo; Joseph Mitchell; Juncai Gao; Kamal Benslama; Kathy McCormick; Kevin Fissum; Konrad Aniol; Krishni Wijesooriya; Louis Bimbot; Ludyvine Morand; Luminita Todor; Marat Rvachev; Mark Jones; Martin Epstein; Meihua Liang; Michael Kuss; Moskov Amarian; Nilanga Liyanage; Oleksandr Glamazdin; Olivier Gayou; Paul Ulmer; Pete Markowitz; Peter Bosted; Holt, R.; Riad Suleiman; Richard Lindgren; Rikki Roche; Robert Michaels; Roman Pomatsalyuk; Ronald Gilman; Ronald Ransome; Salvatore Frullani; Scott Dumalski; Seonho Choi; Sergey Malov; Sonja Dieterich; Steffen Strauch; Stephen Becher; Steve Churchwell; Ting Chang; Viktor Gorbenko; Vina Punjabi; Xiaodong Jiang; Zein-Eddine Meziani; Zhengwei Chai; Wang Xu

2001-01-01

We present measurements of the recoil proton polarization for the d(polarized y, polarized p)n reaction at thetac.m. = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization py vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(y,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime

Polarization holography

DEFF Research Database (Denmark)

Nikolova, L.; Ramanujam, P.S.

Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

THREE-DIMENSIONAL RADIATIVE TRANSFER MODELING OF THE POLARIZATION OF THE SUN'S CONTINUOUS SPECTRUM

International Nuclear Information System (INIS)

Bueno, Javier Trujillo; Shchukina, Nataliya

2009-01-01

Polarized light provides the most reliable source of information at our disposal for diagnosing the physical properties of astrophysical plasmas, including the three-dimensional (3D) structure of the solar atmosphere. Here we formulate and solve the 3D radiative transfer problem of the linear polarization of the solar continuous radiation, which is principally produced by Rayleigh and Thomson scattering. Our approach takes into account not only the anisotropy of the solar continuum radiation but also the symmetry-breaking effects caused by the horizontal atmospheric inhomogeneities produced by the solar surface convection. We show that such symmetry-breaking effects do produce observable signatures in Q/I and U/I, even at the very center of the solar disk where we observe the forward scattering case, but their detection would require obtaining very high resolution linear polarization images of the solar surface. Without spatial and/or temporal resolution U/I ∼ 0 and the only observable quantity is Q/I, whose wavelength variation at a solar disk position close to the limb has been recently determined semi-empirically. Interestingly, our 3D radiative transfer modeling of the polarization of the Sun's continuous spectrum in a well-known 3D hydrodynamical model of the solar photosphere shows remarkable agreement with the semi-empirical determination, significantly better than that obtained via the use of one-dimensional (1D) atmospheric models. Although this result confirms that the above-mentioned 3D model was indeed a suitable choice for our Hanle-effect estimation of the substantial amount of 'hidden' magnetic energy that is stored in the quiet solar photosphere, we have found however some small discrepancies whose origin may be due to uncertainties in the semi-empirical data and/or in the thermal and density structure of the 3D model. For this reason, we have paid some attention also to other (more familiar) observables, like the center-limb variation of the

Polarized electrode enhances biological direct interspecies electron transfer for methane production in upflow anaerobic bioelectrochemical reactor.

Science.gov (United States)

Feng, Qing; Song, Young-Chae; Yoo, Kyuseon; Kuppanan, Nanthakumar; Subudhi, Sanjukta; Lal, Banwari

2018-08-01

The influence of polarized electrodes on the methane production, which depends on the sludge concentration, was investigated in upflow anaerobic bioelectrochemical (UABE) reactor. When the polarized electrode was placed in the bottom zone with a high sludge concentration, the methane production was 5.34 L/L.d, which was 53% higher than upflow anaerobic sludge blanket (UASB) reactor. However, the methane production was reduced to 4.34 L/L.d by placing the electrode in the upper zone of the UABE reactor with lower sludge concentration. In the UABE reactor, the methane production was mainly improved by the enhanced biological direct interspecies electron transfer (bDIET) pathway, and the methane production via the electrode was a minor fraction of less than 4% of total methane production. The polarized electrodes that placed in the bottom zone with a high sludge concentration enhance the bDIET for methane production in the UABE reactor and greatly improve the methane production. Copyright © 2018. Published by Elsevier Ltd.

Comparison of full-sky polarization and radiance observations to radiative transfer simulations which employ AERONET products.

Science.gov (United States)

Pust, Nathan J; Dahlberg, Andrew R; Thomas, Michael J; Shaw, Joseph A

2011-09-12

Visible-band and near infrared polarization and radiance images measured with a ground-based full-sky polarimeter are compared against a successive orders of scattering (SOS) radiative transfer model for 2009 summer cloud-free days in Bozeman, Montana, USA. The polarimeter measures radiance and polarization in 10-nm bands centered at 450 nm, 490 nm, 530 nm, 630 nm, and 700 nm. AERONET products are used to represent aerosols in the SOS model, while MISR satellite BRF products are used for the surface reflectance. While model results generally agree well with observation, the simulated degree of polarization is typically higher than observed data. Potential sources of this difference may include cloud contamination and/or underestimation of the AERONET-retrieved aerosol real refractive index. Problems with the retrieved parameters are not unexpected given the low aerosol optical depth range (0.025 to 0.17 at 500 nm) during the study and the corresponding difficulties that these conditions pose to the AERONET inversion algorithm.

Polarization observables in hard rescattering mechanism of deuteron photodisintegration

Energy Technology Data Exchange (ETDEWEB)

Sargsian, Misak M

2004-05-06

Polarization properties of high energy photodisintegration of the deuteron are studied within the framework of the hard rescattering mechanism (HRM). In HRM, a quark of one nucleon knocked-out by the incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with high relative momentum. Summation of all relevant quark rescattering amplitudes allows us to express the scattering amplitude of the reaction through the convolution of a hard photon-quark interaction vertex, the large angle p-n scattering amplitude and the low momentum deuteron wave function. Within HRM, it is demonstrated that the polarization observables in hard photodisintegration of the deuteron can be expressed through the five helicity amplitudes of NN scattering at high momentum transfer. At 90 deg. CM scattering HRM predicts the dominance of the isovector channel of hard pn rescattering, and it explains the observed smallness of induced, P{sub y} and transfered, C{sub x} polarizations without invoking the argument of helicity conservation. Namely, HRM predicts that P{sub y} and C{sub x} are proportional to the phi{sub 5} helicity amplitude which vanishes at {theta}{sub cm}=90 deg. due to symmetry reasons. HRM predicts also a nonzero value for C{sub z} in the helicity-conserving regime and a positive {sigma} asymmetry which is related to the dominance of the isovector channel in the hard reinteraction. We extend our calculations to the region where large polarization effects are observed in pp scattering as well as give predictions for angular dependences.

Charge-Transfer States in Organic Solar Cells: Understanding the Impact of Polarization, Delocalization, and Disorder

KAUST Repository

Zheng, Zilong

2017-05-08

We investigate the impact of electronic polarization, charge delocalization, and energetic disorder on the charge-transfer (CT) states formed at a planar C60/pentacene interface. The ability to examine large complexes containing up to seven pentacene molecules and three C60 molecules allows us to take explicitly into account the electronic polarization effects. These complexes are extracted from a bilayer architecture modeled by molecular dynamics simulations and evaluated by means of electronic-structure calculations based on long-range-separated functionals (ωB97XD and BNL) with optimized range-separation parameters. The energies of the lowest charge-transfer states derived for the large complexes are in very good agreement with the experimentally reported values. The average singlet-triplet energy splittings of the lowest CT states are calculated not to exceed 10 meV. The rates of geminate recombination as well as of dissociation of the triplet excitons are also evaluated. In line with experiment, our results indicate that the pentacene triplet excitons generated through singlet fission can dissociate into separated charges on a picosecond time scale, despite the fact that their energy in C60/pentacene heterojunctions is slightly lower than the energies of the lowest CT triplet states.

The representation of neutron polarization

International Nuclear Information System (INIS)

Byrne, J.

1979-01-01

Neutron beam polarization representation is discussed under the headings; transfer matrices, coherent parity violation for neutrons, neutron spin rotation in helical magnetic fields, polarization and interference. (UK)

Some issues related to polarized radiative transfer in a multilayer medium with a changing index of refraction

International Nuclear Information System (INIS)

Garcia, R D M

2012-01-01

A couple of issues raised in a recent work on Fresnel boundary and interface conditions for polarized radiative transfer are discussed. The first issue concerns a normalization that has to be performed on the transmission matrix relating the transmitted and incident Stokes vectors at a smooth interface between different materials. It was found that the normalization step is not performed in a correct way in many existing works and so the effects of the two most frequent discrepancies encountered in these works are evaluated for a simple model of an atmosphere-water system. The second issue has to do with a choice of the sign of the parallel component of the amplitude coefficient of reflection R l when constructing the reflection matrix that relates the reflected and incident Stokes vectors at a smooth interface. A computational approach based on the limit to the case with constant index of refraction is used to determine the appropriate sign of R l for polarized radiative transfer calculations in multilayers with different indices of refraction.

Polarized and persistent Ca²⁺ plumes define loci for formation of wall ingrowth papillae in transfer cells.

Science.gov (United States)

Zhang, Hui-Ming; Imtiaz, Mohammad S; Laver, Derek R; McCurdy, David W; Offler, Christina E; van Helden, Dirk F; Patrick, John W

2015-03-01

Transfer cell morphology is characterized by a polarized ingrowth wall comprising a uniform wall upon which wall ingrowth papillae develop at right angles into the cytoplasm. The hypothesis that positional information directing construction of wall ingrowth papillae is mediated by Ca(2+) signals generated by spatiotemporal alterations in cytosolic Ca(2+) ([Ca(2+)]cyt) of cells trans-differentiating to a transfer cell morphology was tested. This hypothesis was examined using Vicia faba cotyledons. On transferring cotyledons to culture, their adaxial epidermal cells synchronously trans-differentiate to epidermal transfer cells. A polarized and persistent Ca(2+) signal, generated during epidermal cell trans-differentiation, was found to co-localize with the site of ingrowth wall formation. Dampening Ca(2+) signal intensity, by withdrawing extracellular Ca(2+) or blocking Ca(2+) channel activity, inhibited formation of wall ingrowth papillae. Maintenance of Ca(2+) signal polarity and persistence depended upon a rapid turnover (minutes) of cytosolic Ca(2+) by co-operative functioning of plasma membrane Ca(2+)-permeable channels and Ca(2+)-ATPases. Viewed paradermally, and proximal to the cytosol-plasma membrane interface, the Ca(2+) signal was organized into discrete patches that aligned spatially with clusters of Ca(2+)-permeable channels. Mathematical modelling demonstrated that these patches of cytosolic Ca(2+) were consistent with inward-directed plumes of elevated [Ca(2+)]cyt. Plume formation depended upon an alternating distribution of Ca(2+)-permeable channels and Ca(2+)-ATPase clusters. On further inward diffusion, the Ca(2+) plumes coalesced into a uniform Ca(2+) signal. Blocking or dispersing the Ca(2+) plumes inhibited deposition of wall ingrowth papillae, while uniform wall formation remained unaltered. A working model envisages that cytosolic Ca(2+) plumes define the loci at which wall ingrowth papillae are deposited. © The Author 2014. Published by Oxford

Dual descriptors within the framework of spin-polarized density functional theory.

Science.gov (United States)

Chamorro, E; Pérez, P; Duque, M; De Proft, F; Geerlings, P

2008-08-14

Spin-polarized density functional theory (SP-DFT) allows both the analysis of charge-transfer (e.g., electrophilic and nucleophilic reactivity) and of spin-polarization processes (e.g., photophysical changes arising from electron transitions). In analogy with the dual descriptor introduced by Morell et al. [J. Phys. Chem. A 109, 205 (2005)], we introduce new dual descriptors intended to simultaneously give information of the molecular regions where the spin-polarization process linking states of different multiplicity will drive electron density and spin density changes. The electronic charge and spin rearrangement in the spin forbidden radiative transitions S(0)-->T(n,pi(*)) and S(0)-->T(pi,pi(*)) in formaldehyde and ethylene, respectively, have been used as benchmark examples illustrating the usefulness of the new spin-polarization dual descriptors. These quantities indicate those regions where spin-orbit coupling effects are at work in such processes. Additionally, the qualitative relationship between the topology of the spin-polarization dual descriptors and the vertical singlet triplet energy gap in simple substituted carbene series has been also discussed. It is shown that the electron density and spin density rearrangements arise in agreement with spectroscopic experimental evidence and other theoretical results on the selected target systems.

Atmospheres and spectra of strongly magnetized neutron stars - II. The effect of vacuum polarization

Science.gov (United States)

Ho, Wynn C. G.; Lai, Dong

2003-01-01

We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B= 1014-1015 G, as appropriate for magnetars. Vacuum polarization modifies the dielectric property of the medium and gives rise to a resonance feature in the opacity; this feature is narrow and occurs at a photon energy that depends on the plasma density. Vacuum polarization can also induce resonant conversion of photon modes via a mechanism analogous to the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism for neutrino oscillation. We construct atmosphere models in radiative equilibrium with an effective temperature of a few ×106 K by solving the full radiative transfer equations for both polarization modes in a fully ionized hydrogen plasma. We discuss the subtleties in treating the vacuum polarization effects in the atmosphere models and present approximate solutions to the radiative transfer problem which bracket the true answer. We show from both analytic considerations and numerical calculations that vacuum polarization produces a broad depression in the X-ray flux at high energies (a few keV <~E<~ a few tens of keV) as compared to models without vacuum polarization; this arises from the density dependence of the vacuum resonance feature and the large density gradient present in the atmosphere. Thus the vacuum polarization effect softens the high-energy tail of the thermal spectrum, although the atmospheric emission is still harder than the blackbody spectrum because of the non-grey opacities. We also show that the depression of continuum flux strongly suppresses the equivalent width of the ion cyclotron line and therefore makes the line more difficult to observe.

$\\Lambda$ and $\\bar{\\Lambda}$ polarization at COMPASS

CERN Document Server

Kang, Donghee

2010-01-01

At the COMPASS experiment $\\Lambda$ and $\\bar{\\Lambda}$ particles are produced with high statistics in deep inelastic scattering (DIS) processes of 160 GeV/c polarized muons. Since both, beam and target, are polarized, various studies on the $\\Lambda$ polarization are possible. We present results on the longitudinal polarization transfer from muons to $\\Lambda$ hyperons produced by scattering off an unpolarized isoscalar target and preliminary results on the transverse $\\Lambda$ polarization with a transversely polarized proton target. The $\\Lambda$ and $\\bar{\\Lambda}$ polarization can be studied by measuring the acceptance corrected angular distribution of its decay products. The longitudinal spin transfers to $\\Lambda$ and $\\bar{\\Lambda}$ produced in the current fragmentation region exhibit different behaviours as a function of $x_{Bj}$ and $x_{F}$. The $x_{Bj}$ and $x_{F}$ dependences of $\\Lambda$ polarization are compatible with zero, while $\\bar{\\Lambda}$ polarization tends to increase with $x_{F}$. Info...

Polarization-based enhancement of ocean color signal for estimating suspended particulate matter: radiative transfer simulations and laboratory measurements.

Science.gov (United States)

Liu, Jia; He, Xianqiang; Liu, Jiahang; Bai, Yan; Wang, Difeng; Chen, Tieqiao; Wang, Yihao; Zhu, Feng

2017-04-17

Absorption and scattering by molecules, aerosols and hydrosols, and the reflection and transmission over the sea surface can modify the original polarization state of sunlight. However, water-leaving radiance polarization, containing embedded water constituent information, has largely been neglected. Here, the efficiency of the parallel polarization radiance (PPR) for enhancing ocean color signal of suspended particulate matter is examined via vector radiative transfer simulations and laboratory experiments. The simulation results demonstrate that the PPR has a slightly higher ocean color signal at the top-of-atmosphere as compared with that of the total radiance. Moreover, both the simulations and laboratory measurements reveal that, compared with total radiance, PPR can effectively enhance the normalized ocean color signal for a large range of observation geometries, wavelengths, and suspended particle concentrations. Thus, PPR has great potential for improving the ocean color signal detection from satellite.

Improved results for the 2H(d, n)3He transverse vector polarization-transfer coefficient Kyy'(0o) at low energies

International Nuclear Information System (INIS)

Roper, C.D.; Dunham, J.D.; Clegg, T.B.; Mendez, A.J.; Tornow, W.; Walter, R.L.

2010-01-01

Measurements of the 2 H(d, n) 3 He transverse vector polarization-transfer coefficient K y y' at 0 o . are reported for 29 outgoing neutron energies between 3.94 and 8.47 MeV. Our new results determine K y y' (0 o ) more accurately than previous data, especially for neutron energies below 5 MeV. Low-energy data for this reaction are important both as a high-intensity source of highly polarized neutrons for nuclear physics studies with polarized neutron beams, and as a test of the emerging theoretical descriptions of the four-body system, where recently substantial progress has been made. (author)

Exact and approximate solutions for the one-dimensional transfer of polarized radiation, and applications to X-ray pulsars

International Nuclear Information System (INIS)

Meszaros, P.; Nagel, W.; Ventura, J.

1979-11-01

Theoretical studies of the radiation from hot, strongly magnetized plasmas, as encountered in pulsars, require a knowledge of solutions to the transfer equations for polarized radiation. We present here an analytic solution of the radiative transfer equations for one-dimensional propagation across a homogeneous slab of finite depth, as well as for a semi-infinite atmosphere. Absorption, scattering and mode-exchange between the two polarizations is included, the role of this latter being crucial. A physical discussion of the solutions for certain limiting cases, and an interpretation in terms of probabilistic (quantum escape approach) arguments, fully corrobrates these solutions, and provides a better intuitive feel for the behaviour of the radiated spectra. Whereas our analytic solutions are valid for any birefringent medium (not necessarily magnetic), our numerical examples and the qualitative discussion presented refer to the particular problem of the radiation from X-ray pulsars. Large scale qualitative changes from the nonmagnetic spectra aae found, which affect both the continum and the spectral lines. (orig.) 891 WL/orig. 892 RDG

Radiative transfer in a strongly magnetized plasma. I. Effects of Anisotropy

International Nuclear Information System (INIS)

Nagel, W.

1981-01-01

We present results of radiative transfer calculations for radiating slabs and columns of strongly magnetized plasma. The angular dependence of the escaping radiation was found numerically by Feautrier's method, using the differential scattering cross sections derived by Ventura. We also give an approximate analytical expression for the anisotropy of the outgoing radiation, based on a system of two coupled diffusion equations for ordinary and extraordinary photons. Giving the polarization dependence of the beaming pattern of radiating slabs as well as columns, we generalize previous results of Basko and Kanno. Some implications for models of the pulsating X-ray source Her X-1 are discussed

Electromagnetically induced absorption due to transfer of coherence and to transfer of population

International Nuclear Information System (INIS)

Goren, C.; Rosenbluh, M.; Wilson-Gordon, A.D.; Friedmann, H.

2003-01-01

The absorption spectrum of a weak probe, interacting with a driven degenerate two-level atomic system, whose ground and excited hyperfine states are F g,e , can exhibit narrow peaks at line center. When the pump and probe polarizations are different, F e =F g +1 and F g >0, the electromagnetically induced absorption (EIA) peak has been shown to be due to the transfer of coherence (TOC) between the excited and ground states via spontaneous decay. We give a detailed explanation of why the TOC that leads to EIA (EIA-TOC) can only take place when ground-state population trapping does not occur, that is, when F e =F g +1. We also explain why EIA-TOC is observed in open systems. We show that EIA can also occur when the pump and probe polarizations are identical and F e =F g +1. This EIA is analogous to an effect that occurs in simple two-level systems when the collisional transfer of population (TOP) from the ground state to a reservoir is greater than that from the excited state. For a degenerate two-level system, the reservoir consists of the Zeeman sublevels of the ground hyperfine state, and of other nearby hyperfine states that do not interact with the pump. We will also discuss the four-wave mixing spectrum under the conditions where EIA-TOC and EIA-TOP occur

Modified compensation algorithm of lever-arm effect and flexural deformation for polar shipborne transfer alignment based on improved adaptive Kalman filter

International Nuclear Information System (INIS)

Wang, Tongda; Cheng, Jianhua; Guan, Dongxue; Kang, Yingyao; Zhang, Wei

2017-01-01

Due to the lever-arm effect and flexural deformation in the practical application of transfer alignment (TA), the TA performance is decreased. The existing polar TA algorithm only compensates a fixed lever-arm without considering the dynamic lever-arm caused by flexural deformation; traditional non-polar TA algorithms also have some limitations. Thus, the performance of existing compensation algorithms is unsatisfactory. In this paper, a modified compensation algorithm of the lever-arm effect and flexural deformation is proposed to promote the accuracy and speed of the polar TA. On the basis of a dynamic lever-arm model and a noise compensation method for flexural deformation, polar TA equations are derived in grid frames. Based on the velocity-plus-attitude matching method, the filter models of polar TA are designed. An adaptive Kalman filter (AKF) is improved to promote the robustness and accuracy of the system, and then applied to the estimation of the misalignment angles. Simulation and experiment results have demonstrated that the modified compensation algorithm based on the improved AKF for polar TA can effectively compensate the lever-arm effect and flexural deformation, and then improve the accuracy and speed of TA in the polar region. (paper)

Testing proton spin models with polarized beams

International Nuclear Information System (INIS)

Ramsey, G.P.

1991-01-01

We review models for spin-weighted parton distributions in a proton. Sum rules involving the nonsinglet components of the structure function xg 1 p help narrow the range of parameters in these models. The contribution of the γ 5 anomaly term depends on the size of the integrated polarized gluon distribution and experimental predictions depend on its size. We have proposed three models for the polarized gluon distributions, whose range is considerable. These model distributions give an overall range is considerable. These model distributions give an overall range of parameters that can be tested with polarized beam experiments. These are discussed with regard to specific predictions for polarized beam experiments at energies typical of UNK

Scattering with polarized neutrons

International Nuclear Information System (INIS)

Schweizer, J.

2007-01-01

In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)

A New Polar Transfer Alignment Algorithm with the Aid of a Star Sensor and Based on an Adaptive Unscented Kalman Filter

Directory of Open Access Journals (Sweden)

Jianhua Cheng

2017-10-01

Full Text Available Because of the harsh polar environment, the master strapdown inertial navigation system (SINS has low accuracy and the system model information becomes abnormal. In this case, existing polar transfer alignment (TA algorithms which use the measurement information provided by master SINS would lose their effectiveness. In this paper, a new polar TA algorithm with the aid of a star sensor and based on an adaptive unscented Kalman filter (AUKF is proposed to deal with the problems. Since the measurement information provided by master SINS is inaccurate, the accurate information provided by the star sensor is chosen as the measurement. With the compensation of lever-arm effect and the model of star sensor, the nonlinear navigation equations are derived. Combined with the attitude matching method, the filter models for polar TA are designed. An AUKF is introduced to solve the abnormal information of system model. Then, the AUKF is used to estimate the states of TA. Results have demonstrated that the performance of the new polar TA algorithm is better than the state-of-the-art polar TA algorithms. Therefore, the new polar TA algorithm proposed in this paper is effectively to ensure and improve the accuracy of TA in the harsh polar environment.

A New Polar Transfer Alignment Algorithm with the Aid of a Star Sensor and Based on an Adaptive Unscented Kalman Filter.

Science.gov (United States)

Cheng, Jianhua; Wang, Tongda; Wang, Lu; Wang, Zhenmin

2017-10-23

Because of the harsh polar environment, the master strapdown inertial navigation system (SINS) has low accuracy and the system model information becomes abnormal. In this case, existing polar transfer alignment (TA) algorithms which use the measurement information provided by master SINS would lose their effectiveness. In this paper, a new polar TA algorithm with the aid of a star sensor and based on an adaptive unscented Kalman filter (AUKF) is proposed to deal with the problems. Since the measurement information provided by master SINS is inaccurate, the accurate information provided by the star sensor is chosen as the measurement. With the compensation of lever-arm effect and the model of star sensor, the nonlinear navigation equations are derived. Combined with the attitude matching method, the filter models for polar TA are designed. An AUKF is introduced to solve the abnormal information of system model. Then, the AUKF is used to estimate the states of TA. Results have demonstrated that the performance of the new polar TA algorithm is better than the state-of-the-art polar TA algorithms. Therefore, the new polar TA algorithm proposed in this paper is effectively to ensure and improve the accuracy of TA in the harsh polar environment.

Mapping the local organization of cell membranes using excitation-polarization-resolved confocal fluorescence microscopy.

Science.gov (United States)

Kress, Alla; Wang, Xiao; Ranchon, Hubert; Savatier, Julien; Rigneault, Hervé; Ferrand, Patrick; Brasselet, Sophie

2013-07-02

Fluorescence anisotropy and linear dichroism imaging have been widely used for imaging biomolecular orientational distributions in protein aggregates, fibrillar structures of cells, and cell membranes. However, these techniques do not give access to complete orientational order information in a whole image, because their use is limited to parts of the sample where the average orientation of molecules is known a priori. Fluorescence anisotropy is also highly sensitive to depolarization mechanisms such as those induced by fluorescence energy transfer. A fully excitation-polarization-resolved fluorescence microscopy imaging that relies on the use of a tunable incident polarization and a nonpolarized detection is able to circumvent these limitations. We have developed such a technique in confocal epifluorescence microscopy, giving access to new regions of study in the complex and heterogeneous molecular organization of cell membranes. Using this technique, we demonstrate morphological changes at the subdiffraction scale in labeled COS-7 cell membranes whose cytoskeleton is perturbed. Molecular orientational order is also seen to be affected by cholesterol depletion, reflecting the strong interplay between lipid-packing regions and their nearby cytoskeleton. This noninvasive optical technique can reveal local organization in cell membranes when used as a complement to existing methods such as generalized polarization. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Effect of 3D Polarization profiles on polarization measurements and colliding beam experiments

Energy Technology Data Exchange (ETDEWEB)

Fischer, W.; Bazilevsky, A.

2011-08-18

The development of polarization profiles are the primary reason for the loss of average polarization. Polarization profiles have been parametrized with a Gaussian distribution. We derive the effect of 3-dimensional polarization profiles on the measured polarization in polarimeters, as well as the observed polarization and the figure of merit in single and double spin experiments. Examples from RHIC are provided. The Relativistic Heavy Ion Collider (RHIC) is the only collider of spin polarized protons. During beam acceleration and storage profiles of the polarization P develop, which affect the polarization measured in a polarimeter, and the polarization and figure of merit (FOM) in colliding beam experiments. We calculate these for profiles in all dimensions, and give examples for RHIC. Like in RHIC we call the two colliding beams Blue and Yellow. We use the overbar to designate intensity-weighted averages in polarimeters (e.g. {bar P}), and angle brackets to designate luminosity-weighted averages in colliding beam experiments (e.g.

).

Effect of 3D Polarization profiles on polarization measurements and colliding beam experiments

International Nuclear Information System (INIS)

Fischer, W.; Bazilevsky, A.

2011-01-01

The development of polarization profiles are the primary reason for the loss of average polarization. Polarization profiles have been parametrized with a Gaussian distribution. We derive the effect of 3-dimensional polarization profiles on the measured polarization in polarimeters, as well as the observed polarization and the figure of merit in single and double spin experiments. Examples from RHIC are provided. The Relativistic Heavy Ion Collider (RHIC) is the only collider of spin polarized protons. During beam acceleration and storage profiles of the polarization P develop, which affect the polarization measured in a polarimeter, and the polarization and figure of merit (FOM) in colliding beam experiments. We calculate these for profiles in all dimensions, and give examples for RHIC. Like in RHIC we call the two colliding beams Blue and Yellow. We use the overbar to designate intensity-weighted averages in polarimeters (e.g. (bar P)), and angle brackets to designate luminosity-weighted averages in colliding beam experiments (e.g. ).

Reduction of coating induced polarization aberrations by controlling the polarization state variation

International Nuclear Information System (INIS)

Li, Yanghui; Shen, Weidong; Zheng, Zhenrong; Zhang, Yueguang; Liu, Xu; Hao, Xiang

2011-01-01

The mechanism of coating induced polarization state variation is analysed by the Jones matrix. Pauli spin matrices are used to establish the relationship between coating induced polarization state variation and polarization aberrations. To reduce coating induced polarization aberrations, we propose that δ = 0 and T s = T p at arbitrary incident angle should be appended as two additional optimization goals of optical coating design when the requirements of transmittance are met. Two typical anti-reflection (AR) coatings are designed and the polarization state variation induced by them is simulated. The MTF (modulation transfer function) calculated by polarization ray tracing is applied to evaluate the polarization aberrations of the practical lithography objective system with the two AR coatings. All the obtained results show that the coating induced polarization aberrations can be reduced by optimizing the angle dependent properties of the optical coating without additional optical elements

Incorporation of charge transfer into the explicit polarization fragment method by grand canonical density functional theory.

Science.gov (United States)

Isegawa, Miho; Gao, Jiali; Truhlar, Donald G

2011-08-28

Molecular fragmentation algorithms provide a powerful approach to extending electronic structure methods to very large systems. Here we present a method for including charge transfer between molecular fragments in the explicit polarization (X-Pol) fragment method for calculating potential energy surfaces. In the conventional X-Pol method, the total charge of each fragment is preserved, and charge transfer between fragments is not allowed. The description of charge transfer is made possible by treating each fragment as an open system with respect to the number of electrons. To achieve this, we applied Mermin's finite temperature method to the X-Pol wave function. In the application of this method to X-Pol, the fragments are open systems that partially equilibrate their number of electrons through a quasithermodynamics electron reservoir. The number of electrons in a given fragment can take a fractional value, and the electrons of each fragment obey the Fermi-Dirac distribution. The equilibrium state for the electrons is determined by electronegativity equalization with conservation of the total number of electrons. The amount of charge transfer is controlled by re-interpreting the temperature parameter in the Fermi-Dirac distribution function as a coupling strength parameter. We determined this coupling parameter so as to reproduce the charge transfer energy obtained by block localized energy decomposition analysis. We apply the new method to ten systems, and we show that it can yield reasonable approximations to potential energy profiles, to charge transfer stabilization energies, and to the direction and amount of charge transferred. © 2011 American Institute of Physics

Photoinduced Electron Transfer of PAMAM Dendrimer-Zinc(II) Porphyrin Associates at Polarized Liquid|Liquid Interfaces.

Science.gov (United States)

Nagatani, Hirohisa; Sakae, Hiroki; Torikai, Taishi; Sagara, Takamasa; Imura, Hisanori

2015-06-09

The heterogeneous photoinduced electron-transfer reaction of the ion associates between NH2-terminated polyamidoamine (PAMAM) dendrimers and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato zinc(II) (ZnTPPS(4-)) was studied at the polarized water|1,2-dichloroethane (DCE) interface. The positive photocurrent arising from the photoreduction of ZnTPPS(4-) by a lipophilic quencher, decamethylferrocene, in the interfacial region was significantly enhanced by the ion association with the PAMAM dendrimers. The photocurrent response of the dendrimer-ZnTPPS(4-) associates was dependent on the pH condition and on the generation of dendrimer. A few cationic additives such as polyallylamine and n-octyltrimethyammonium were also examined as alternatives to the PAMAM dendrimer, but the magnitude of the photocurrent enhancement was rather small. The high photoreactivity of the dendrimer-ZnTPPS(4-) associates was interpreted mainly as a result of the high interfacial concentration of photoreactive porphyrin units associated stably with the dendrimer which was preferably adsorbed at the polarized water|DCE interface. The photochemical data observed in the second and fourth generation PAMAM dendrimer systems demonstrated that the higher generation dendrimer which can incorporate a porphyrin molecule more completely in the interior is less efficient for the photocurrent enhancement at the interface. These results indicated that the photoreactivity of ionic reactant at a polarized liquid|liquid interface can readily be modified via ion association with the charged dendrimer.

Improved Results for the H-2(d, n)(3) He Transverse Vector Polarization- Transfer Coefficient K-y(y)' (0 degrees) at Low Energies

International Nuclear Information System (INIS)

Roper, C.D.; Clegg, T.; Dunham, J.D.; Mendez, Anthony J. II; Tornow, W.; Walter, R.L.

2010-01-01

Measurements of the H-2(d, n)(3) He transverse vector polarization-transfer coefficient K-y(y)' at 0 degrees. are reported for 29 outgoing neutron energies between 3.94 and 8.47MeV. Our new results determine K-y(y)' (0 degrees) more accurately than previous data, especially for neutron energies below 5MeV. Low-energy data for this reaction are important both as a high-intensity source of highly polarized neutrons for nuclear physics studies with polarized neutron beams, and as a test of the emerging theoretical descriptions of the four-body system, where recently substantial progress has been made.

Spatiotemporal polarization gradients in phase-bearing light

International Nuclear Information System (INIS)

Lembessis, V. E.; Babiker, M.

2010-01-01

It is shown how the interference of two circularly polarized laser beams endowed with orbital angular momentum can give rise to spatial and temporal polarization gradients, displaying axial as well as angular symmetry properties. Illustrations are given with reference to circularly polarized Laguerre-Gaussian beams as typical light beams carrying orbital angular momentum.

Polarized X-Ray Emission from Magnetized Neutron Stars: Signature of Strong-Field Vacuum Polarization

Science.gov (United States)

Lai, Dong; Ho, Wynn C.

2003-08-01

In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

Polarized x-ray emission from magnetized neutron stars: signature of strong-field vacuum polarization.

Science.gov (United States)

Lai, Dong; Ho, Wynn C G

2003-08-15

In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

Measurement of polarization-transfer to bound protons in carbon and its virtuality dependence

Science.gov (United States)

Izraeli, D.; Brecelj, T.; Achenbach, P.; Ashkenazi, A.; Böhm, R.; Cohen, E. O.; Distler, M. O.; Esser, A.; Gilman, R.; Kolar, T.; Korover, I.; Lichtenstadt, J.; Mardor, I.; Merkel, H.; Mihovilovič, M.; Müller, U.; Olivenboim, M.; Piasetzky, E.; Ron, G.; Schlimme, B. S.; Schoth, M.; Sfienti, C.; Širca, S.; Štajner, S.; Strauch, S.; Thiel, M.; Weber, A.; Yaron, I.; A1 Collaboration

2018-06-01

We measured the ratio Px /Pz of the transverse to longitudinal components of polarization transferred from electrons to bound protons in 12C by the 12C (e → ,e‧ p →) process at the Mainz Microtron (MAMI). We observed consistent deviations from unity of this ratio normalized to the free-proton ratio, (Px /Pz) 12C /(Px /Pz) 1H, for both s- and p-shell knocked out protons, even though they are embedded in averaged local densities that differ by about a factor of two. The dependence of the double ratio on proton virtuality is similar to the one for knocked out protons from 2H and 4He, suggesting a universal behavior. It further implies no dependence on average local nuclear density.

Statistics of cosmic microwave background polarization

International Nuclear Information System (INIS)

Kamionkowski, M.; Kosowsky, A.; Stebbins, A.

1997-01-01

We present a formalism for analyzing a full-sky temperature and polarization map of the cosmic microwave background. Temperature maps are analyzed by expanding over the set of spherical harmonics to give multipole moments of the two-point correlation function. Polarization, which is described by a second-rank tensor, can be treated analogously by expanding in the appropriate tensor spherical harmonics. We provide expressions for the complete set of temperature and polarization multipole moments for scalar and tensor metric perturbations. Four sets of multipole moments completely describe isotropic temperature and polarization correlations; for scalar metric perturbations one set is identically zero, giving the possibility of a clean determination of the vector and tensor contributions. The variance with which the multipole moments can be measured in idealized experiments is evaluated, including the effects of detector noise, sky coverage, and beam width. Finally, we construct coordinate-independent polarization two-point correlation functions, express them in terms of the multipole moments, and derive small-angle limits. copyright 1997 The American Physical Society

Measurement of the polarization parameter in 24 GeV/c pp elastic scattering at large momentum transfers

CERN Document Server

Antille, J; Dick, Louis; Gonidec, A; Kuroda, K; Kyberd, P; Michalowicz, A; Perret-Gallix, D; Salmon, G L; Werlen, M

1981-01-01

A measurement of the polarization parameter P/sub 0/ in pp elastic scattering has been made 24 GeV/c over the range of momentum transfer squared 0.7< mod t mod <5.0 (GeV/c)/sup 2/. The structure of P/sub 0/ has changed compared to typical lower energy data. The second peak is suppressed and a dip has appeared at mod t mod =3.6 (GeV/c)/sup 2/. (31 refs).

Comparison of discrete ordinate and Monte Carlo simulations of polarized radiative transfer in two coupled slabs with different refractive indices.

Science.gov (United States)

Cohen, D; Stamnes, S; Tanikawa, T; Sommersten, E R; Stamnes, J J; Lotsberg, J K; Stamnes, K

2013-04-22

A comparison is presented of two different methods for polarized radiative transfer in coupled media consisting of two adjacent slabs with different refractive indices, each slab being a stratified medium with no change in optical properties except in the direction of stratification. One of the methods is based on solving the integro-differential radiative transfer equation for the two coupled slabs using the discrete ordinate approximation. The other method is based on probabilistic and statistical concepts and simulates the propagation of polarized light using the Monte Carlo approach. The emphasis is on non-Rayleigh scattering for particles in the Mie regime. Comparisons with benchmark results available for a slab with constant refractive index show that both methods reproduce these benchmark results when the refractive index is set to be the same in the two slabs. Computed results for test cases with coupling (different refractive indices in the two slabs) show that the two methods produce essentially identical results for identical input in terms of absorption and scattering coefficients and scattering phase matrices.

Studies of Silyl-Transfer Photochemical Reactions of N-[(Trimethylsilyl)alkyl]saccharins

Energy Technology Data Exchange (ETDEWEB)

Cho, Dae Won; Oh, Sun Wha; Park, Hea Jung; Yoon, Ung Chan [Pusan National University, Busan (Korea, Republic of); Kim, Dong Uk [Daegu National University of Education, Daegu (Korea, Republic of); Xue, Jin Ying [Harbin Normal University, Harbin (China); Mariano, Patrick S. [University of New Mexico, Albuquerque (United States)

2010-09-15

Photochemical studies of N-[(trimethylsilyl)alkyl]saccharins were carried out to investigate their photochemical behavior. Depending on the nature of the substrate and the solvent system employed, reactions of these substances can take place by either SET-promoted silyl migration from carbon to either the amide carbonyl or sulfonyl oxygen or by a N-S homolysis route. The results of the current studies show that an azomethine ylide, arising from a SET-promoted silyl migration pathway, is generated in photoreactions of N-[(trimethylsilyl)methyl]saccharin and this intermediate reacts to give various photoproducts depending on the conditions employed. In addition, irradiation of N-[(trimethylsily)ethyl]saccharin produces an excited state that reacts through two pathways, the relative importance is governed by solvent polarity and protic nature. Finally, photoirradiation of N-[(trimethylsilyl)propyl]saccharin in a highly polar solvent system comprised of 35% aqueous MeOH gives rise to formation of a tricyclic pyrrolizidine and saccharin that generated via competitive SET-promoted silyl transfer and γ-hydrogen abstraction pathways.

Studies of Silyl-Transfer Photochemical Reactions of N-[(Trimethylsilyl)alkyl]saccharins

International Nuclear Information System (INIS)

Cho, Dae Won; Oh, Sun Wha; Park, Hea Jung; Yoon, Ung Chan; Kim, Dong Uk; Xue, Jin Ying; Mariano, Patrick S.

2010-01-01

Photochemical studies of N-[(trimethylsilyl)alkyl]saccharins were carried out to investigate their photochemical behavior. Depending on the nature of the substrate and the solvent system employed, reactions of these substances can take place by either SET-promoted silyl migration from carbon to either the amide carbonyl or sulfonyl oxygen or by a N-S homolysis route. The results of the current studies show that an azomethine ylide, arising from a SET-promoted silyl migration pathway, is generated in photoreactions of N-[(trimethylsilyl)methyl]saccharin and this intermediate reacts to give various photoproducts depending on the conditions employed. In addition, irradiation of N-[(trimethylsily)ethyl]saccharin produces an excited state that reacts through two pathways, the relative importance is governed by solvent polarity and protic nature. Finally, photoirradiation of N-[(trimethylsilyl)propyl]saccharin in a highly polar solvent system comprised of 35% aqueous MeOH gives rise to formation of a tricyclic pyrrolizidine and saccharin that generated via competitive SET-promoted silyl transfer and γ-hydrogen abstraction pathways

Plasma polarization spectroscopy

International Nuclear Information System (INIS)

Iwamae, Atsushi; Horimoto, Yasuhiro; Fujimoto, Takashi; Hasegawa, Noboru; Sukegawa, Kouta; Kawachi, Tetsuya

2005-01-01

The electron velocity distribution function (EVDF) in plasma can be anisotropic in laser-produced plasmas. We have developed a new technique to evaluate the polarization degree of the emission lines in the extreme vacuum ultra violet wavelength region. The polarization of the emission lines and the continuums from the lithium-like nitrogen and from helium- and hydrogen-like carbon in recombining plasma is evaluated. Particle simulation in the velocity space gives the time scale for relaxation of anisotropic EVDFs. (author)

Design of a tensor polarized deuterium target polarized by spin-exchange with optically pumped NA

International Nuclear Information System (INIS)

Green, M.C.

1984-01-01

A proposed design for a tensor polarized deuterium target (approx. 10 15 atoms/cm 2 ) for nuclear physics studies in an electron storage ring accelerator is presented. The deuterium atoms undergo electron spin exchange with a highly polarized sodium vapor; this polarization is transferred to the deuterium nuclei via the hyperfine interaction. The deuterium nuclei obtain their tensor polarization through repeated electron spin exchange/hyperfine interactions. The sodium vapor polarization is maintained by standard optical pumping techniques. Model calculations are presented in detail leading to a discussion of the expected performance and the technical obstacles to be surmounted in the development of such a target

Design of a tensor polarized deuterium target polarized by spin-exchange with optically pumped NA

International Nuclear Information System (INIS)

Green, M.C.

1984-05-01

A proposed design for a tensor polarized deuterium target (approx. 10 15 atoms/cm 2 ) for nuclear physics studies in an electron storage ring accelerator is presented. The deuterium atoms undergo electron spin exchange with a highly polarized sodium vapor; this polarization is transferred to the deuterium nuclei via the hyperfine interaction. The deuterium nuclei obtain their tensor polarization through repeated electron spin exchange/hyperfine interactions. The sodium vapor polarization is maintained by standard optical pumping techniques. Model calculations are presented in detail leading to a discussion of the expected performance and the technical obstacles to be surmounted in the development of such a target. 15 references, 10 figures

The polar 2e/12c bond in phenalenyl-azaphenalenyl hetero-dimers: Stronger stacking interaction and fascinating interlayer charge transfer

Energy Technology Data Exchange (ETDEWEB)

Zhong, Rong-Lin; Li, Zhi-Ru, E-mail: hlxu@nenu.edu.cn, E-mail: lzr@jlu.edu.cn [Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); Xu, Hong-Liang, E-mail: hlxu@nenu.edu.cn, E-mail: lzr@jlu.edu.cn [Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)

2016-08-07

An increasing number of chemists have focused on the two-electron/multicenter bond (2e/mc) that was first introduced to interpret the bonding mechanism of radical dimers. Herein, we report the polar two-electron/twelve center (2e/12c) bonding character in a series of phenalenyl-azaphenalenyl radical hetero-dimers. Interestingly, the bonding energy of weaker polar hetero-dimer (P-TAP) is dominated by the overlap of the two different singly occupied molecular orbital of radicals, while that of stronger polar hetero-dimer (P-HAP) is dominated by the electrostatic attraction. Results show that the difference between the electronegativity of the monomers plays a prominent role in the essential attribution of the polar 2e/12c bond. Correspondingly, a stronger stacking interaction in the hetero-dimer could be effectively achieved by increasing the difference of nitrogen atoms number between the monomers. It is worthy of note that an interesting interlayer charge transfer character is induced in the polar hetero-dimers, which is dependent on the difference between the electronegativity of the monomers. It is our expectation that the new knowledge about the bonding nature of radical hetero-dimers might provide important information for designing radical based functional materials with various applications.

Feasibility studies of a polarized positron source based on the Bremsstrahlung of polarized electrons

International Nuclear Information System (INIS)

Dumas, J.

2011-09-01

The nuclear and high-energy physics communities have shown a growing interest in the availability of high current, highly-polarized positron beams. A sufficiently energetic polarized photon or lepton incident on a target may generate, via Bremsstrahlung and pair creation within a solid target foil, electron-positron pairs that should carry some fraction of the initial polarization. Recent advances in high current (> 1 mA) spin polarized electron sources at Jefferson Lab offer the perspective of creating polarized positrons from a low energy electron beam. This thesis discusses polarization transfer from electrons to positrons in the perspective of the design optimization of a polarized positron source. The PEPPo experiment, aiming at a measurement of the positron polarization from a low energy (< 10 MeV) highly spin polarized electron beam is discussed. A successful demonstration of this technique would provide an alternative scheme for the production of low energy polarized positrons and useful information for the optimization of the design of polarized positron sources in the sub-GeV energy range. (author)

Markov chain formalism for generalized radiative transfer in a plane-parallel medium, accounting for polarization

International Nuclear Information System (INIS)

Xu, Feng; Davis, Anthony B.; Diner, David J.

2016-01-01

A Markov chain formalism is developed for computing the transport of polarized radiation according to Generalized Radiative Transfer (GRT) theory, which was developed recently to account for unresolved random fluctuations of scattering particle density and can also be applied to unresolved spectral variability of gaseous absorption as an improvement over the standard correlated-k method. Using Gamma distribution to describe the probability density function of the extinction or absorption coefficient, a shape parameter a that quantifies the variability is introduced, defined as the mean extinction or absorption coefficient squared divided by its variance. It controls the decay rate of a power-law transmission that replaces the usual exponential Beer-Lambert-Bouguer law. Exponential transmission, hence classic RT, is recovered when a→∞. The new approach is verified to high accuracy against numerical benchmark results obtained with a custom Monte Carlo method. For a<∞, angular reciprocity is violated to a degree that increases with the spatial variability, as observed for finite portions of real-world cloudy scenes. While the degree of linear polarization in liquid water cloudbows, supernumerary bows, and glories is affected by spatial heterogeneity, the positions in scattering angle of these features are relatively unchanged. As a result, a single-scattering model based on the assumption of subpixel homogeneity can still be used to derive droplet size distributions from polarimetric measurements of extended stratocumulus clouds. - Highlights: • A Markov chain formalism is developed for Generalized Radiative Transfer theory. • Angular reciprocity is violated to a degree that increases with spatial variability. • The positions of cloudbows and glories in scattering angle are relatively unchanged.

Polarization-dependent optics using gauge-field metamaterials

International Nuclear Information System (INIS)

Liu, Fu; Xiao, Shiyi; Li, Jensen; Wang, Saisai; Hang, Zhi Hong

2015-01-01

We show that effective gauge field for photons with polarization-split dispersion surfaces, being realized using uniaxial metamaterials, can be used for polarization control with unique opportunities. The metamaterials with the proposed gauge field correspond to a special choice of eigenpolarizations on the Poincaré sphere as pseudo-spins, in contrary to those from either conventional birefringent crystals or optical active media. It gives rise to all-angle polarization control and a generic route to manipulate photon trajectories or polarizations in the pseudo-spin domain. As demonstrations, we show beam splitting (birefringent polarizer), all-angle polarization control, unidirectional polarization filter, and interferometer as various polarization control devices in the pseudo-spin domain. We expect that more polarization-dependent devices can be designed under the same framework

Investigation of the NN interaction from polarization transfer experiments in low energy pp scattering

Energy Technology Data Exchange (ETDEWEB)

Weidmann, R.; Albert, J.; Glombik, A.; Kretschmer, W.; Nebert, P.; Rauscher, A. (Physikalisches Inst., Univ. Erlangen-Nuernberg (Germany)); Clajus, M.; Egun, P.M.; Grueebler, W.; Hautle, P. (Inst. fuer Mittelenergiephysik, ETH, Zurich (Switzerland)); Schmelzbach, P.A. (Paul Scherrer Inst., F1, Accelerator Div., Villigen (Switzerland)); Slaus, I. (Inst. Ruder Boscovic, Zagreb (Croatia))

1993-03-01

The polarization-Transfer observables K[sub y][sup y']([theta]), K[sub x][sup x']([theta]) and K[sub z][sup x']([theta]) for proton-proton scattering have been measured at E[sub p]=25.68 MeV. A simultaneous phase-shift analysis of these new data with differential cross section and analyzing power data at the same energy resulted in a very accurate determination of the p-wave phase-shift combinations [Delta][sub C], [Delta][sub LS] and [Delta][sub T] and of the [sup 3]F[sub 2]-[sup 3]P[sub 2] mixing parameter [epsilon][sub 2]. With this complete set of high precision data a critical test of microscopic NN-potential models has been performed. (orig.).

Single Transition-to-single Transition Polarization Transfer (ST2-PT) in [15N,1H]-TROSY

International Nuclear Information System (INIS)

Pervushin, Konstantin V.; Wider, Gerhard; Wuethrich, Kurt

1998-01-01

This paper describes the use of single transition-to-single transition polarization transfer (ST2-PT) in transverse relaxation-optimized spectroscopy (TROSY), where it affords a √2 sensitivity enhancement for kinetically stable amide 15N-1H groups in proteins. Additional, conventional improvements of [15N,1H]-TROSY include that signal loss for kinetically labile 15N-1H groups due to saturation transfer from the solvent water is suppressed with the 'water flip back' technique and that the number of phase steps is reduced to two, which is attractive for the use of [15N,1H]-TROSY as an element in more complex NMR schemes. Finally, we show that the impact of the inclusion of the 15N steady-state magnetization (Pervushin et al., 1998) on the signal-to-noise ratio achieved with [15N,1H]-TROSY exceeds by up to two-fold the gain expected from the gyromagnetic ratios of 1H and 15N

Transfer of polarized light in planetary atmospheres basic concepts and practical methods

CERN Document Server

Hovenier, Joop W; Domke, Helmut

2004-01-01

The principal elements of the theory of polarized light transfer in planetary atmospheres are expounded in a systematic but concise way. Basic concepts and practical methods are emphasized, both for single and multiple scattering of electromagnetic radiation by molecules and particles in the atmospheres of planets in the Solar System, including the Earth, and beyond. A large part of the book is also useful for studies of light scattering by particles in comets, the interplanetary and interstellar medium, circumstellar disks, reflection nebulae, water bodies like oceans and suspensions of particles in a gas or liquid in the laboratory. Throughout the book symmetry principles, such as the reciprocity principle and the mirror symmetry principle, are employed. In this way the theory is made more transparent and easier to understand than in most papers on the subject. In addition, significant computational reductions, resulting from symmetry principles, are presented. Hundreds of references to relevant literature ...

Zero-field spin transfer oscillators based on magnetic tunnel junction having perpendicular polarizer and planar free layer

Directory of Open Access Journals (Sweden)

Bin Fang

2016-12-01

Full Text Available We experimentally studied spin-transfer-torque induced magnetization oscillations in an asymmetric MgO-based magnetic tunnel junction device consisting of an in-plane magnetized free layer and an out-of-plane magnetized polarizer. A steady auto-oscillation was achieved at zero magnetic field and room temperature, with an oscillation frequency that was strongly dependent on bias currents, with a large frequency tunability of 1.39 GHz/mA. Our results suggest that this new structure has a high potential for new microwave device designs.

Design of reproducible polarized and non-polarized edge filters using genetic algorithm

International Nuclear Information System (INIS)

Ejigu, Efrem Kebede; Lacquet, B M

2010-01-01

Recent advancement in optical fibre communications technology is partly due to the advancement of optical thin film technology. The advancement of optical thin film technology includes the development of new and existing optical filter design methods. The genetic algorithm is one of the new design methods that show promising results in designing a number of complicated design specifications. It is the finding of this study that the genetic algorithm design method, through its optimization capability, can give more reliable and reproducible designs of any specifications. The design method in this study optimizes the thickness of each layer to get to the best possible solution. Its capability and unavoidable limitations in designing polarized and non-polarized edge filters from absorptive and dispersive materials is well demonstrated. It is also demonstrated that polarized and non-polarized designs from the genetic algorithm are reproducible with great success. This research has accomplished the great task of formulating a computer program using the genetic algorithm in a Matlab environment for the design of a reproducible polarized and non-polarized filters of any sort from any kind of materials

Achievement of transportable polarized D, in solid HD, with a one day passively maintained polarization

International Nuclear Information System (INIS)

Honig, A.; Alexander, N.; Fan, Q.; Wei, X.; Yu, Y.Y.

1993-01-01

At a previous workshop, we discussed evaporating solid HD with spin-polarized deuterons to produce a high density polarized deuteron gaseous internal target. Since then, we have achieved in solid HD 38% polarized D, whose spin-lattice relaxation time at 1.5 K in a field of 0.1 T is of the order of a day. Optimization of the procedure with the present apparatus should result in 60% D polarization, and longer polarization holding times. The polarized sample of approximately 0.2 cm 3 volume used here is extractable from the dilution refrigerator with a cold-transfer apparatus which maintains the sample at or below 5 K, insuring retention of the high polarization. It is subsequently insertable into a variety of systems, and employable as a polarized solid, liquid, or gas. We are exploring the possibility of extending the polarization maintenance time to about a month (with a matched 1 month preparation time), of polarizing metastably H as well as D, and of producing much larger samples, of the order of 100 cm 3

Invited article: polarization "down under": the polarized time-of-flight neutron reflectometer PLATYPUS.

Science.gov (United States)

Saerbeck, T; Klose, F; Le Brun, A P; Füzi, J; Brule, A; Nelson, A; Holt, S A; James, M

2012-08-01

This review presents the implementation and full characterization of the polarization equipment of the time-of-flight neutron reflectometer PLATYPUS at the Australian Nuclear Science and Technology Organisation (ANSTO). The functionality and efficiency of individual components are evaluated and found to maintain a high neutron beam polarization with a maximum of 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers with efficiencies of 99.7% give full control over the incident and scattered neutron spin direction over the whole wavelength spectrum available in the instrument. The first scientific experiments illustrate data correction mechanisms for finite polarizations and reveal an extraordinarily high reproducibility for measuring magnetic thin film samples. The setup is now fully commissioned and available for users through the neutron beam proposal system of the Bragg Institute at ANSTO.

POLARIZED LINE FORMATION WITH LOWER-LEVEL POLARIZATION AND PARTIAL FREQUENCY REDISTRIBUTION

Energy Technology Data Exchange (ETDEWEB)

Supriya, H. D.; Sampoorna, M.; Nagendra, K. N.; Ravindra, B. [Indian Institute of Astrophysics, Bangalore 560034 (India); Stenflo, J. O. [Institute of Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland)

2016-09-10

In the well-established theories of polarized line formation with partial frequency redistribution (PRD) for a two-level and two-term atom, it is generally assumed that the lower level of the scattering transition is unpolarized. However, the existence of unexplained spectral features in some lines of the Second Solar Spectrum points toward a need to relax this assumption. There exists a density matrix theory that accounts for the polarization of all the atomic levels, but it is based on the flat-spectrum approximation (corresponding to complete frequency redistribution). In the present paper we propose a numerical algorithm to solve the problem of polarized line formation in magnetized media, which includes both the effects of PRD and the lower level polarization (LLP) for a two-level atom. First we derive a collisionless redistribution matrix that includes the combined effects of the PRD and the LLP. We then solve the relevant transfer equation using a two-stage approach. For illustration purposes, we consider two case studies in the non-magnetic regime, namely, the J {sub a} = 1, J {sub b} = 0 and J {sub a} = J {sub b} = 1, where J {sub a} and J {sub b} represent the total angular momentum quantum numbers of the lower and upper states, respectively. Our studies show that the effects of LLP are significant only in the line core. This leads us to propose a simplified numerical approach to solve the concerned radiative transfer problem.

The Transfer of Resonance Line Polarization with Partial Frequency Redistribution in the General Hanle–Zeeman Regime

Energy Technology Data Exchange (ETDEWEB)

Ballester, E. Alsina; Bueno, J. Trujillo [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Belluzzi, L., E-mail: ealsina@iac.es [Istituto Ricerche Solari Locarno, CH-6605 Locarno Monti (Switzerland)

2017-02-10

The spectral line polarization encodes a wealth of information about the thermal and magnetic properties of the solar atmosphere. Modeling the Stokes profiles of strong resonance lines is, however, a complex problem both from a theoretical and computational point of view, especially when partial frequency redistribution (PRD) effects need to be taken into account. In this work, we consider a two-level atom in the presence of magnetic fields of arbitrary intensity (Hanle–Zeeman regime) and orientation, both deterministic and micro-structured. Working within the framework of a rigorous PRD theoretical approach, we have developed a numerical code that solves the full non-LTE radiative transfer problem for polarized radiation, in one-dimensional models of the solar atmosphere, accounting for the combined action of the Hanle and Zeeman effects, as well as for PRD phenomena. After briefly discussing the relevant equations, we describe the iterative method of solution of the problem and the numerical tools that we have developed and implemented. We finally present some illustrative applications to two resonance lines that form at different heights in the solar atmosphere, and provide a detailed physical interpretation of the calculated Stokes profiles. We find that magneto-optical effects have a strong impact on the linear polarization signals that PRD effects produce in the wings of strong resonance lines. We also show that the weak-field approximation has to be used with caution when PRD effects are considered.

Development of Efficient and Robust Heteronuclear Cross-Polarization Techniques for Biological Solid-State Nuclear Magnetic Resonance Spectroscopy

DEFF Research Database (Denmark)

Jain, Sheetal Kumar

2014-01-01

→13C and 1H→14N polarization transfers. The deuterium experiments were performed on deuterated glutamine and outer membrane protein G samples, while the nitrogen experiments were carried out on ammonium nitrate and alanine samples. Moreover, experiments with low power on the 2H channel are presented......→13C polarization transfer to facilitate 2-dimensional experiments detecting 14N in the indirect dimension are shown. Finally, to test the polarization transfer efficiency with very large chemical shift anisotropies, 19F→13C polarization transfer experiments for Poly Tetra Fluoro Ethylene (PTFE...

Radiative transfer in atmosphere-sea ice-ocean system

Energy Technology Data Exchange (ETDEWEB)

Jin, Z.; Stamnes, K.; Weeks, W.F. [Univ. of Alaska, Fairbanks, AK (United States); Tsay, S.C. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

1996-04-01

Radiative energy is critical in controlling the heat and mass balance of sea ice, which significantly affects the polar climate. In the polar oceans, light transmission through the atmosphere and sea ice is essential to the growth of plankton and algae and, consequently, to the microbial community both in the ice and in the ocean. Therefore, the study of radiative transfer in the polar atmosphere, sea ice, and ocean system is of particular importance. Lacking a properly coupled radiative transfer model for the atmosphere-sea ice-ocean system, a consistent study of the radiative transfer in the polar atmosphere, snow, sea ice, and ocean system has not been undertaken before. The radiative transfer processes in the atmosphere and in the ice and ocean have been treated separately. Because the radiation processes in the atmosphere, sea ice, and ocean depend on each other, this separate treatment is inconsistent. To study the radiative interaction between the atmosphere, clouds, snow, sea ice, and ocean, a radiative transfer model with consistent treatment of radiation in the coupled system is needed and is under development.

CpG Oligodeoxynucleotides Enhance the Efficacy of Adoptive Cell Transfer Using Tumor Infiltrating Lymphocytes by Modifying the Th1 Polarization and Local Infiltration of Th17 Cells

Directory of Open Access Journals (Sweden)

Lin Xu

2010-01-01

Full Text Available Adoptive cell transfer immunotherapy using tumor infiltrating lymphocytes (TILs was an important therapeutic strategy against tumors. But the efficacy remains limited and development of new strategies is urgent. Recent evidence suggested that CpG-ODNs might be a potent candidate for tumor immunotherapy. Here we firstly reported that CpG-ODNs could significantly enhance the antitumor efficacy of adoptively transferred TILs in vivo accompanied by enhanced activity capacity and proliferation of CD8+ T cells and CD8+ T cells, as well as a Th1 polarization immune response. Most importantly, we found that CpG-ODNs could significantly elevate the infiltration of Th17 cells in tumor mass, which contributed to anti-tumor efficacy of TILs in vivo. Our findings suggested that CpG ODNs could enhance the anti-tumor efficacy of adoptively transferred TILs through modifying Th1 polarization and local infiltration of Th17 cells, which might provide a clue for developing a new strategy for ACT based on TILs.

Characteristics of the polar cap at ionospheric levels and present understanding of the physical processes that give rise to these characteristics

International Nuclear Information System (INIS)

Brekke, A.

1983-01-01

This chapter discusses the relationship between the interplanetary magnetic field (IMF) and various polar cap current systems, such as the DP2-system and the S /SUB q/ P-system. The disagreements concerning these systems are examined. Topics considered include the polar cap (a result of an open magnetosphere); studies of the polar cap magnetic field variations; the DP2-current system and its relation to the IMF; the polar cap current system during a northward IMF; the azimuthal component of IMF and its influence on the polar cap magnetic field variations; the electric potential distribution on the polar cap; rocket observations of the polar cap electric field; the auroral arcs as a visible trace of the ionospheric convection; neutral wind measurements in the polar cap F-region; and further studies of polar cap dynamics. The focus is on the polar region inside the auroral oval. It is suggested that more research is needed of the polar cap current system in order to understand the magnetosphereionosphere coupling, with the polar cap ionospheric conductivity distribution being the most crucial parameter

Thermodynamics of polarized relativistic matter

Energy Technology Data Exchange (ETDEWEB)

Kovtun, Pavel [Department of Physics and Astronomy, University of Victoria,PO Box 1700 STN CSC, Victoria BC, V8W 2Y2 (Canada)

2016-07-05

We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.

Baryon spectroscopy with polarization observables from CLAS

Energy Technology Data Exchange (ETDEWEB)

Strauch, Steffen [Univ. of South Carolina, Columbia, SC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2016-11-01

The spectrum of nucleon excitations is dominated by broad and overlapping resonances. Polarization observables in photoproduction reactions are key in the study of these excitations. They give indispensable constraints to partial-wave analyses and help clarify the spectrum. A series of polarized photoproduction experiments have been performed at the Thomas Jefferson National Accelerator Facility with the CEBAF Large Acceptance Spectrometer (CLAS). These measurements include data with linearly and circularly polarized tagged-photon beams, longitudinally and transversely polarized proton and deuterium targets, and recoil polarizations through the observation of the weak decay of hyperons. An overview of these studies and recent results will be given.

Ejectile polarization and nuclear orbitals

International Nuclear Information System (INIS)

Ohnishi, A.; Maruyama, T.; Horiuchi, H.

1992-01-01

Ejectile polarization phenomena are studied by the use of 'Quantum Molecular Dynamics plus external mean field' model. It is shown that the far-side contribution increases as the incident energy increases or the target charge decreases. The incident energy and the target dependence of ejectile polarization data is reproduced qualitatively. The near- and far-side contributions themselves are calculated to be almost monotone functions of ejectile momentum as is predicted in a simple projectile fragmentation scheme without the assumption that the linear and angular momentum transfers are negligible, and their statistical average results in various shapes in ejectile polarization

EXPLORING THE POLARIZATION OF GLUONS IN THE NUCLEON.

Energy Technology Data Exchange (ETDEWEB)

STRATMANN,M.; VOGELSANG,W.

2007-10-22

We give an overview of the current status of investigations of the polarization of gluons in the nucleon. We describe some of the physics of the spin-dependent gluon parton distribution and its phenomenology in high-energy polarized hadronic scattering. We also review the recent experimental results.

Robust techniques for polarization and detection of nuclear spin ensembles

Science.gov (United States)

Scheuer, Jochen; Schwartz, Ilai; Müller, Samuel; Chen, Qiong; Dhand, Ish; Plenio, Martin B.; Naydenov, Boris; Jelezko, Fedor

2017-11-01

Highly sensitive nuclear spin detection is crucial in many scientific areas including nuclear magnetic resonance spectroscopy, magnetic resonance imaging (MRI), and quantum computing. The tiny thermal nuclear spin polarization represents a major obstacle towards this goal which may be overcome by dynamic nuclear spin polarization (DNP) methods. The latter often rely on the transfer of the thermally polarized electron spins to nearby nuclear spins, which is limited by the Boltzmann distribution of the former. Here we utilize microwave dressed states to transfer the high (>92 % ) nonequilibrium electron spin polarization of a single nitrogen-vacancy center (NV) induced by short laser pulses to the surrounding 13C carbon nuclear spins. The NV is repeatedly repolarized optically, thus providing an effectively infinite polarization reservoir. A saturation of the polarization of the nearby nuclear spins is achieved, which is confirmed by the decay of the polarization transfer signal and shows an excellent agreement with theoretical simulations. Hereby we introduce the polarization readout by polarization inversion method as a quantitative magnetization measure of the nuclear spin bath, which allows us to observe by ensemble averaging macroscopically hidden polarization dynamics like Landau-Zener-Stückelberg oscillations. Moreover, we show that using the integrated solid effect both for single- and double-quantum transitions nuclear spin polarization can be achieved even when the static magnetic field is not aligned along the NV's crystal axis. This opens a path for the application of our DNP technique to spins in and outside of nanodiamonds, enabling their application as MRI tracers. Furthermore, the methods reported here can be applied to other solid state systems where a central electron spin is coupled to a nuclear spin bath, e.g., phosphor donors in silicon and color centers in silicon carbide.

Transfers of Colloidal Silica from Water into Organic Solvents of Intermediate Polarities

Science.gov (United States)

Kasseh; Keh

1998-01-15

Dispersions of discrete metal-oxide submicroparticles in organic solvents of medium polarities are uneasy to generate and weakly documented. We address this topic along two general methods focusing on silica. Successive transfers of colloidal particles from water into n-propanol and then into 1,2-dichloroethane by azeotropic distillation yield a stable organosol. The particles are found to be propanol-coated by surface esterification to the extent of 0.40 nm2 per molecule. Alternatively, centrifugation-redispersion cycles make it possible to obtain stable suspensions of unaltered silica in methanol and acetonitrile starting from an aqueous silicasol. Particles are characterized by various methods including nitrogen adsorption, transmission electron microscopy, dynamic light scattering, and electrophoresis. The stabilities of these suspensions in various organic solvents are investigated with special concern for the role of residual water. Stabilization of silica in methanol is inconspicuously related to solvent permittivity and prominently dependent on the presence of adsorbed water. In contrast, the acetonitrile silicasol, which is unaffected by residual water, displays electrophoretic behavior compatible with electrostatic stabilization. Copyright 1998 Academic Press. Copyright 1998Academic Press

Large enhancement of deuteron polarization with frequency modulated microwaves

CERN Document Server

AUTHOR|(CDS)2067425; Arik, S; Arvidson, A; Badelek, B; Ballintijn, M K; Bardin,; Baum, G; Berglund, P; Betev, L; Birda, I G; Birsa, R; Bjrkholm, P; Bonner, B E; de Botton, N; Boutemeur, M; Bradamante, Franco; Bressan, A; Brullc, A; Buchanan, J; Bültmann, S; Burtin, E; Cavata, C; Chen, J P; Clement, J; Clocchiatti, M; Corcoran, M D; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Deshpande, S; Dalla Torre, A; Van Dantzig, R; Dhawan, S; Dulya, C; Dyring, A; Eichblatt, S; Faivre, Jean-Claude; Fasching, D; Day, D; Feinstein, F; Fernández, C; Frois, B; Garabatos, C; Garzón, J A; Gaussiran, T; Giorgi, M; von Goeler, E; Goloutvin, Igor A; Gómez, A; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Gülmez, E; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, D; von Harrach, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; De Jong, M; Kabu, E M; Kageya, T; Kaiser, R; Karev, A; Kessler, H J; Ketel, T J; Kiryushin, Yu T; Kishi, A; Kisselev, Yu; Klostermann, L; Krämer, Dietrich; Kukhtin, V; Kyynarinen, J; Lamanna, M; Landgraf, U; Lau, V; Krivokhijinea, K; Layda, T; Le Go, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Lindqvist, T; Litmaath, M; López-Ponte, S; Loewe, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B; McCarthy, J S; van Middelkoop, K; Medved, G; Miller, D; Mitchell, J; Mori, K; Moromisato, J; Mutchler, G S; Nagaitsev, A; Nassalski, J; Naumann, Lutz; Neganov, B; Niinikoski, T O; Oberski, J E J; Ogawa, A; Okumi, S; Ozben, C S; Penzo, Aldo L; Pérez, C A; Perrot-Kunne, F; Piegaia, R; Pinsky, L; Platchkov, S; Pló, M; Pose, D; Postma, D; Peshekhonov, H; Pretz, J; Pussieux, T; Pyrlik, J; Reyhancan, I; Rieubland, Jean Michel; Rijllart, A; Roberts, J B; Rock, S E; Rodríguez, M; Rondio, E; Rondon, O; Ropelewski, Leszek; Rosado, A; Sabo, I; Saborido, J; Salvato, G; Sandacz, A; Sanders, D; Savin, I; Schiavon, Paolo; Schüler, K P; Segel, R; Seitz, R; Semertzidis, Y; Sergeev, S; Sever, F; Shanahan, P; Sichtermann, E P; Smirnov, G; Staude, A; Steinmetz, A; Stuhrmann, H; Teichert, K M; Tessarotto, F; Thiel, W; Velasco, M; Vogt, J; Voss, R; Weinstein, R; Whitten, C; Willumeit, R; Windmolders, R; Wislicki, W; Witzmann, A; Yañez, A; Zanetti, A M; Zhao, J; Zamiatin, N I

1996-01-01

We report a large enhancement of 1.7 in deuteron polarization up to values of 0.6 due to frequency modulation of the polarizing microwaves in a two liters polarized target using the method of dynamic nuclear polarization. This target was used during a deep inelastic polarized muon-deuteron scattering experiment at CERN. Measurements of the electron paramagnetic resonance absorption spectra show that frequency modulation gives rise to additional microwave absorption in the spectral wings. Although these results are not understood theoretically, they may provide a useful testing ground for the deeper understanding of dynamic nuclear polarization.

Observations on Polar Coding with CRC-Aided List Decoding

Science.gov (United States)

2016-09-01

TECHNICAL REPORT 3041 September 2016 Observations on Polar Coding with CRC-Aided List Decoding David Wasserman Approved for public release. SSC...described in [2, 3]. In FY15 and FY16 we used cyclic redundancy check (CRC)-aided polar list decoding [4]. Section 2 describes the basics of polar coding ...and gives details of the encoders and decoders we used. In the course of our research, we performed simulations of polar codes in hundreds of cases

Polarized Radiative Transfer of a Cirrus Cloud Consisting of Randomly Oriented Hexagonal Ice Crystals: The 3 x 3 Approximation for Non-Spherical Particles

Science.gov (United States)

Stamnes, S.; Ou, S. C.; Lin, Z.; Takano, Y.; Tsay, S. C.; Liou, K.N.; Stamnes, K.

2016-01-01

The reflection and transmission of polarized light for a cirrus cloud consisting of randomly oriented hexagonal columns were calculated by two very different vector radiative transfer models. The forward peak of the phase function for the ensemble-averaged ice crystals has a value of order 6 x 10(exp 3) so a truncation procedure was used to help produce numerically efficient yet accurate results. One of these models, the Vectorized Line-by-Line Equivalent model (VLBLE), is based on the doubling- adding principle, while the other is based on a vector discrete ordinates method (VDISORT). A comparison shows that the two models provide very close although not entirely identical results, which can be explained by differences in treatment of single scattering and the representation of the scattering phase matrix. The relative differences in the reflected I and Q Stokes parameters are within 0.5 for I and within 1.5 for Q for all viewing angles. In 1971 Hansen showed that for scattering by spherical particles the 3 x 3 approximation is sufficient to produce accurate results for the reflected radiance I and the degree of polarization (DOP), and he conjectured that these results would hold also for non-spherical particles. Simulations were conducted to test Hansen's conjecture for the cirrus cloud particles considered in this study. It was found that the 3 x 3 approximation also gives accurate results for the transmitted light, and for Q and U in addition to I and DOP. For these non-spherical ice particles the 3 x 3 approximation leads to an absolute error 2 x 10(exp -6) for the reflected and transmitted I, Q and U Stokes parameters. Hence, it appears to be an excellent approximation, which significantly reduces the computational complexity and burden required for multiple scattering calculations.

Genetic modification of adeno-associated viral vector type 2 capsid enhances gene transfer efficiency in polarized human airway epithelial cells.

Science.gov (United States)

White, April F; Mazur, Marina; Sorscher, Eric J; Zinn, Kurt R; Ponnazhagan, Selvarangan

2008-12-01

Cystic fibrosis (CF) is a common genetic disease characterized by defects in the expression of the CF transmembrane conductance regulator (CFTR) gene. Gene therapy offers better hope for the treatment of CF. Adeno-associated viral (AAV) vectors are capable of stable expression with low immunogenicity. Despite their potential in CF gene therapy, gene transfer efficiency by AAV is limited because of pathophysiological barriers in these patients. Although a few AAV serotypes have shown better transduction compared with the AAV2-based vectors, gene transfer efficiency in human airway epithelium has still not reached therapeutic levels. To engineer better AAV vectors for enhanced gene delivery in human airway epithelium, we developed and characterized mutant AAV vectors by genetic capsid modification, modeling the well-characterized AAV2 serotype. We genetically incorporated putative high-affinity peptide ligands to human airway epithelium on the GH loop region of AAV2 capsid protein. Six independent mutant AAV were constructed, containing peptide ligands previously reported to bind with high affinity for known and unknown receptors on human airway epithelial cells. The vectors were tested on nonairway cells and nonpolarized and polarized human airway epithelial cells for enhanced infectivity. One of the mutant vectors, with the peptide sequence THALWHT, not only showed the highest transduction in undifferentiated human airway epithelial cells but also indicated significant transduction in polarized cells. Interestingly, this modified vector was also able to infect cells independently of the heparan sulfate proteoglycan receptor. Incorporation of this ligand on other AAV serotypes, which have shown improved gene transfer efficiency in the human airway epithelium, may enhance the application of AAV vectors in CF gene therapy.

Low-energy positron-argon collisions by using parameter-free positron correlation polarization potentials

International Nuclear Information System (INIS)

Jain, A.

1990-01-01

We report differential, integral, and momentum-transfer cross sections and the scattering length (A 0 ) for positron (e + )-argon scattering at low energies below the positronium formation threshold. An optical-potential approach is employed in which the repulsive Coulombic interaction is calculated exactly at the Hartree-Fock level and the attractive polarization and correlation effects are included approximately via a parameter-free positron correlation polarization (PCP) potential recently proposed by us. The PCP model is based on the correlation energy var-epsilon corr of one positron in a homogeneous electron gas; in the outside region, the var-epsilon corr is joined smoothly with the correct asymptotic form of the polarization interaction (-α 0 /2r 4 , where α 0 is the target polarizability) where they cross each other for the first time. The total optical potential of the e + -argon system is treated exactly in a partial-wave analysis to extract the scattering parameters. It is found that the PCP potential gives much better qualitative results, particularly for the differential cross sections and the scattering length, than the corresponding results obtained from an electron polarization potential used as such for the positron case. We also discuss the ''critical'' points (representing the minima in the differential scattering) in the low-energy e + -Ar scattering. The present results involve no fitting procedure

Production of spin-polarized unstable nuclei by using polarized electron capture process

International Nuclear Information System (INIS)

Shimizu, S.

1998-01-01

Measurements of emitted radiation from spin polarized nuclei are used to get information on electromagnetic moment of ground state unstable nuclei together with spin or parity state of excited states of their decayed (daughter) nuclei. These data are known to be useful for experimental investigation into the structure of unstable nuclei far from the stability line. The present study aims to establish a general method applicable to 11 Be and 16 N nuclei. To produce spin polarization, a new method in which the electron spin polarization of Rb is firstly produced by laser pumping, then the electron is transferred to the unstable nuclear beam (RNB) when they passes through the Rb vapor is proposed. Finally the polarized RNB will be implanted into superfluid helium to remain with a long spin-relaxation time. Future experimental set up for the above measurement adopted in the available radioactive nuclear beam facilities is briefly described. (Ohno, S.)

Probing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations

Energy Technology Data Exchange (ETDEWEB)

Gold, Roman; McKinney, Jonathan C. [Department of Physics and Joint Space-Science Institute, University of Maryland, College Park, MD 20742 (United States); Johnson, Michael D.; Doeleman, Sheperd S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-03-10

Magnetic fields are believed to drive accretion and relativistic jets in black hole accretion systems, but the magnetic field structure that controls these phenomena remains uncertain. We perform general relativistic (GR) polarized radiative transfer of time-dependent three-dimensional GR magnetohydrodynamical simulations to model thermal synchrotron emission from the Galactic Center source Sagittarius A* (Sgr A*). We compare our results to new polarimetry measurements by the Event Horizon Telescope (EHT) and show how polarization in the visibility (Fourier) domain distinguishes and constrains accretion flow models with different magnetic field structures. These include models with small-scale fields in disks driven by the magnetorotational instability as well as models with large-scale ordered fields in magnetically arrested disks. We also consider different electron temperature and jet mass-loading prescriptions that control the brightness of the disk, funnel-wall jet, and Blandford–Znajek-driven funnel jet. Our comparisons between the simulations and observations favor models with ordered magnetic fields near the black hole event horizon in Sgr A*, though both disk- and jet-dominated emission can satisfactorily explain most of the current EHT data. We also discuss how the black hole shadow can be filled-in by jet emission or mimicked by the absence of funnel jet emission. We show that stronger model constraints should be possible with upcoming circular polarization and higher frequency (349 GHz) measurements.

Projective geometry for polarization in geometric quantization

International Nuclear Information System (INIS)

Campbell, P.; Dodson, C.T.J.

1976-12-01

It is important to know the extent to which the procedure of geometric quantization depends on a choice of polarization of the symplectic manifold that is the classical phase space. Published results have so far been restricted to real and transversal polarizations. Here we also consider these cases by presenting a formulation in terms of projective geometry. It turns out that there is a natural characterization of real transversal polarizations and maps among them using projective concepts. We give explicit constructions for Rsup(2n)

Modeling charge polarization voltage for large lithium-ion batteries in electric vehicles

Directory of Open Access Journals (Sweden)

Yan Jiang

2013-06-01

Full Text Available Purpose: Polarization voltage of the lithium-ion battery is an important parameter that has direct influence on battery performance. The paper aims to analyze the impedance characteristics of the lithium-ion battery based on EIS data. Design/methodology/approach: The effects of currents, initial SOC of the battery on charge polarization voltage are investigated, which is approximately linear function of charge current. The change of charge polarization voltage is also analyzed with the gradient analytical method in the SOC domain. The charge polarization model with two RC networks is presented, and parts of model parameters like Ohmic resistance and charge transfer impedance are estimated by both EIS method and battery constant current testing method. Findings: This paper reveals that the Ohmic resistance accounts for much contribution to battery total polarization compared to charge transfer impedance. Practical implications: Experimental results demonstrate the efficacy of the model with the proposed identification method, which provides the foundation for battery charging optimization. Originality/value: The paper analyzed the impedance characteristics of the lithium-ion battery based on EIS data, presented a charge polarization model with two RC networks, and estimated parameters like Ohmic resistance and charge transfer impedance.

Polarization experiments with hadronic and electromagnetic probes

International Nuclear Information System (INIS)

Punjabi, V.

1993-01-01

The following research activities were carried out during the past year Calibration of focal plane polarimeter POMME up to 2.4 GeV at Saturne National Laboratory (LNS) in Saclay. Measurement of tensor analyzing power T 20 and polarization transfer κ 0 at Saturne up to 2.1 GeV in elastic backward dp scattering rvec dp → rvec pd. Measurement of tensor analyzing power T 20 at synchrophasotron in Dubha up to 4.4 Gev in elastic backward dp scattering rvec dp → pd. Resubmission of conditionally Approved G EP proposal 89-14 at CEBAF. Start construction of focal plane polarimeter (FPP) for CEBAF hall A hadron spectrometer. The planned work for the next year includes: Construction of FPP for CEBAF hall A hadron spectrometer; measurement of polarization transfer κ 0 and tensor analyzing power T 20 in elastic backward dp scattering at Saturne; measurements of tensor analyzing power in 1 H( 6 Li,d)X, 1 H( 6 Li,α)X, 1 H( 6 Li,t)X and 1 H( 6 Li, 3 He)X reactions at Saturne; and study of polarization transfer in 2 H(rvec e,e'rvec p)n reaction at Bates

Polarization Measurements in Neutral Pion Photoproduction

International Nuclear Information System (INIS)

C. Jones; Krishni Wijesooriya; B. Fox; Andrei Afanasev; Moscov Amaryan; Konrad Aniol; Stephen Becher; Kamal Benslama; Louis Bimbot; Peter Bosted; Edward Brash; John Calarco; Zhengwei Chai; C. Chang; Ting Chang; Jian-Ping Chen; Seonho Choi; Eugene Chudakov; Steve Churchwell; Domenick Crovelli; Sonja Dieterich; Scott Dumalski; Dipangkar Dutta; Martin Epstein; Kevin Fissum; Salvatore Frullani; Haiyan Gao; Juncai Gao; Franco Garibaldi; Olivier Gayou; Ronald Gilman; Oleksandr Glamazdin; Charles Glashausser; Javier Gomez; Viktor Gorbenko; Ole Hansen; Roy Holt; Jordan Hovdebo; Garth Huber; Kees de Jager; Xiaodong Jiang; Mark Jones; Jim Kelly; Edward Kinney; Edgar Kooijman; Gerfried Kumbartzki; Michael Kuss; John LeRose; Meme Liang; Richard Lindgren; Nilanga Liyanage; Sergey Malov; Demetrius Margaziotis; Pete Markowitz; Kathy McCormick; Dave Meekins; Zein-Eddine Meziani; Robert Michaels; Joe Mitchell; Ludyvine Morand; Charles Perdrisat

2002-01-01

We present measurements of the recoil proton polarization for the 1 H(gamma-vector,p-vector)pi 0 reaction for theta c.m. pi = 60 o -135 o and for photon energies up to 4.1 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. Various theoretical models are compared with the results. No evidence for hadron helicity conservation is observed. Models that employ factorization are not favored. It appears from the strong angular dependence of the induced polarization at photon energies of 2.5 and 3.1 GeV that a relatively high spin resonance or background amplitude might exist in this energy region

Simultaneously 'pushing' and 'pulling' graphene oxide into low-polar solvents through a designed interface.

Science.gov (United States)

Liu, Zhen; Liu, Jingquan; Wang, Yichao; Razal, Joselito M; Francis, Paul S; Biggs, Mark J; Barrow, Colin J; Yang, Wenrong

2018-08-03

Dispersing graphene oxide (GO) in low-polar solvents can realize a perfect self-assembly with functional molecules and application in removal of organic impurities that only dissolve in low-polar solvents. The surface chemistry of GO plays an important role in its dispersity in these solvents. The direct transfer of hydrophilic GO into low-polar solvents, however, has remained an experimental challenge. In this study, we design an interface to transfer GO by simultaneously 'pushing and pulling' the nanosheets into low-polar solvents. Our approach is outstanding due to the ability to obtain monolayers of chemically reduced GO (CRGO) with designed surface properties in the organic phase. Using the transferred GO or CRGO dispersions, we have fabricated GO/fullerene nanocomposites and assessed the ability of CRGOs for dye adsorption. We hope our work can provide a universal approach for the phase transfer of other nanomaterials.

Polarization and charge-transfer effect on the transport properties in two-dimensional electron gases/LaNiO3 heterostructure

Science.gov (United States)

Chen, M. J.; Ning, X. K.; Wang, Z. J.; Liu, P.; Wang, S. F.; Wang, J. L.; Fu, G. S.; Ma, S.; Liu, W.; Zhang, Z. D.

2018-01-01

The film thickness dependent transport properties of the LaNiO3 (LNO) layer epitaxially grown on LaAlO3/SrTiO3 (LAO) 2-dimensional electronic gas (2DEG) have been investigated. The ultrathin LNO films grown on the 2DEG have a sheet resistance below the values of h/e2 in all temperature ranges. The electron density is enhanced by more than one order of magnitude by capping LNO films. X-ray photoelectron spectroscopy shows that the interface undergoes unambiguous charge transfer and electronic reconstruction, leading to modulation doping of such atomically engineered complex oxide heterointerfaces. The polar-catastrophe of the 2DEG is directly linked to the electronic structure and transport properties of the LNO. The transport properties can be well modulated by the thickness of the LAO in the 2DEG, and the data can be well fitted with the polar-catastrophe scenario. These results suggest a general approach to tunable functional films in oxide heterostructures with the 2DEG.

Green Wireless Power Transfer Networks

NARCIS (Netherlands)

Liu, Q.; Golinnski, M.; Pawelczak, P.; Warnier, M.

2016-01-01

wireless power transfer network (WPTN) aims to support devices with cable-less energy on-demand. Unfortunately, wireless power transfer itself-especially through radio frequency radiation rectification-is fairly inefficient due to decaying power with distance, antenna polarization, etc.

Markov chain formalism for generalized radiative transfer in a plane-parallel medium, accounting for polarization

Science.gov (United States)

Xu, Feng; Davis, Anthony B.; Diner, David J.

2016-11-01

A Markov chain formalism is developed for computing the transport of polarized radiation according to Generalized Radiative Transfer (GRT) theory, which was developed recently to account for unresolved random fluctuations of scattering particle density and can also be applied to unresolved spectral variability of gaseous absorption as an improvement over the standard correlated-k method. Using Gamma distribution to describe the probability density function of the extinction or absorption coefficient, a shape parameter a that quantifies the variability is introduced, defined as the mean extinction or absorption coefficient squared divided by its variance. It controls the decay rate of a power-law transmission that replaces the usual exponential Beer-Lambert-Bouguer law. Exponential transmission, hence classic RT, is recovered when a→∞. The new approach is verified to high accuracy against numerical benchmark results obtained with a custom Monte Carlo method. For a<∞, angular reciprocity is violated to a degree that increases with the spatial variability, as observed for finite portions of real-world cloudy scenes. While the degree of linear polarization in liquid water cloudbows, supernumerary bows, and glories is affected by spatial heterogeneity, the positions in scattering angle of these features are relatively unchanged. As a result, a single-scattering model based on the assumption of subpixel homogeneity can still be used to derive droplet size distributions from polarimetric measurements of extended stratocumulus clouds.

Hyperon polarization: theory and experiments

International Nuclear Information System (INIS)

Magnin, J.; Simao, F.R.A.

1996-01-01

We give a brief review of the experimental situation concerning hyperon polarization. We mention also the current models developed to understand the experimental results and make some comments on some theoretical aspects contained in the Thomas precession model. (author). 8 ref

Polarization transfer in inelastic scattering and pionic models of the EMC effect

International Nuclear Information System (INIS)

Moss, J.M.

1985-01-01

At the 1982 Telluride Conference Magda Ericson spoke about the interest in a measurement of the sigma vector . q vector or spin-longitudinal nuclear response function. It inspired our collaboration to propose a LAMPF experiment, which was subsequently approved, and run in September 1983. In the intervening time the interest has increased dramatically in connection with the European Muon Collaboration (EMC) effect, and the exciting possibility that this ultra high-energy physics result may have to do with nuclear pions - and, hence, the isovector sigma vector . q vector nuclear response function. In this talk I will give a brief introduction to the EMC effect and its interpretation in terms of excess nuclear pions. This model establishes a connection between the vastly different scales of the EMC experiment (approx. 200 GeV deep-inelastic muon scattering) and the Los Alamos experiment (500 MeV polarized-proton quasifree scattering). Following this I will describe the Los Alamos experiment and its interpretation in terms of excess nuclear pions. Finally I will indulge in some speculation about quark effects in nuclei based on the EMC and Los Alamos experimental results. 29 refs

Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

Energy Technology Data Exchange (ETDEWEB)

Mao, Jirong; Wang, Jiancheng, E-mail: jirongmao@mail.ynao.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, 650011 Kunming, Yunnan Province (China)

2017-04-01

Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radio bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.

Three-dimensional Radiative Transfer Simulations of the Scattering Polarization of the Hydrogen Lyalpha Line in a Magnetohydrodynamic Model of the Chromosphere-Corona Transition Region

Czech Academy of Sciences Publication Activity Database

Štěpán, Jiří; Trujillo Bueno, J.; Leenaarts, J.; Carlsson, M.

2015-01-01

Roč. 803, č. 2 (2015), 65/1-65/15 ISSN 0004-637X R&D Projects: GA ČR GPP209/12/P741 Grant - others:EU(XE) COST action MP1104 Institutional support: RVO:67985815 Keywords : polarization * radiative transfer * scattering Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.909, year: 2015

Magnetic excitations and polarized neutrons

International Nuclear Information System (INIS)

Shirane, G.

1985-01-01

We review the historical development of polarized beam techniques for studies of condensed matter physics. In particular we describe, in some detail, the recent advance of the triple axis technique with polarization analysis. It is now possible to carry out quantitative characterization of magnetic cross sections S(Q,ω), in absolute units, for a wide range of energy and momentum transfers. We will discuss some examples of recent inelastic measurements on 3d ferromagnets and heavy Fermions. 35 refs., 11 figs., 2 tabs

Vacuum nonlinear electrodynamic polarization effects in hard emission of pulsars and magnetars

Energy Technology Data Exchange (ETDEWEB)

Denisov, V.I.; Sokolov, V.A.; Svertilov, S.I., E-mail: vid.msu@yandex.ru, E-mail: sokolov.sev@inbox.ru, E-mail: sis@coronas.ru [Physics Department, Moscow State University, Moscow (Russian Federation)

2017-09-01

The nonlinear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on the electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum (nonlinear electrodynamics is obtained. It has been shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and the rest of pulse can have arbitrary polarization. The observational possibilities of vacuum birefringence are discussed. In this paper we give the estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum nonlinear electrodynamics birefringence.

Momentum transfer dependence of generalized parton distributions

Energy Technology Data Exchange (ETDEWEB)

Sharma, Neetika [Indian Institute of Science Education and Research Mohali, S.A.S. Nagar, Punjab (India)

2016-11-15

We revisit the model for parametrization of the momentum dependence of nucleon generalized parton distributions in the light of recent MRST measurements of parton distribution functions (A.D. Martin et al., Eur. Phys. J. C 63, 189 (2009)). Our parametrization method with a minimum set of free parameters give a sufficiently good description of data for Dirac and Pauli electromagnetic form factors of proton and neutron at small and intermediate values of momentum transfer. We also calculate the GPDs for up- and down-quarks by decomposing the electromagnetic form factors for the nucleon using the charge and isospin symmetry and also study the evolution of GPDs to a higher scale. We further investigate the transverse charge densities for both the unpolarized and transversely polarized nucleon and compare our results with Kelly's distribution. (orig.)

Fundamental research with polarized slow neutrons

International Nuclear Information System (INIS)

Krupchitsky, P.A.

1987-01-01

In the last twenty years polarized beams of slow neutrons have been used effectively in fundamental research in nuclear physics. This book gives a thorough introduction to these experimental methods including the most recent techniques of generating and analyzing polarized neutron beams. It clearly shows the close relationship between elementary particle physics and nuclear physics. The book not only addresses specialists but also those interested in the foundations of elementary particle and nuclear physics. With 42 figs

Using Polarization features of visible light for automatic landmine detection

NARCIS (Netherlands)

Jong, W. de; Schavemaker, J.G.M.

2007-01-01

This chapter describes the usage of polarization features of visible light for automatic landmine detection. The first section gives an introduction to land-mine detection and the usage of camera systems. In section 2 detection concepts and methods that use polarization features are described.

Spin-locking and cross-polarization under magic-angle spinning of uniformly labeled solids.

Science.gov (United States)

Hung, Ivan; Gan, Zhehong

2015-07-01

Spin-locking and cross-polarization under magic-angle spinning are investigated for uniformly (13)C and (15)N labeled solids. In particular, the interferences from chemical shift anisotropy, and (1)H heteronuclear and (13)C homonuclear dipolar couplings are identified. The physical origin of these interferences provides guidelines for selecting the best (13)C and (15)N polarization transfer rf fields. Optimal settings for both the zero- and double-quantum cross-polarization transfer mechanisms are recommended. Copyright © 2015 Elsevier Inc. All rights reserved.

Polarized radiative transfer through terrestrial atmosphere accounting for rotational Raman scattering

Science.gov (United States)

Lelli, Luca; Rozanov, Vladimir V.; Vountas, Marco; Burrows, John P.

2017-10-01

This paper is devoted to the phenomenological derivation of the vector radiative transfer equation (VRTE) accounting for first-order source terms of rotational Raman scattering (RRS), which is responsible for the in-filling of Fraunhofer and telluric lines by inelastic scattered photons. The implementation of the solution of the VRTE within the framework of the forward-adjoint method is given. For the Ca II and the oxygen A-band (O2 A) spectral windows, values of reflectance, degree of linear polarization (DOLP) and in-filling, in zenith and nadir geometry, are compared with results given in literature. Moreover, the dependence of these quantities on the columnar loading and vertical layering of non-spherical dust aerosols is investigated, together with their changes as function of two habits of ice crystals, modeled as regular icosahedra and severely rough aggregated columns. Bi-directional effects of an underlying polarizing surface are accounted for. The forward simulations are performed for one selected wavelength in the continuum and one in the strong absorption of the O2 A, as their combination can be exploited for the spaceborne retrieval of aerosol and cloud properties. For this reason, we also mimic seasonal maps of reflectance, DOLP and in-filling, that are prototypical measurements of the Ultraviolet-Visible-Near Infrared (UVN) sensor, at a nominal spectral resolution of 0.12 nm. UVN is the core payload of the upcoming European Sentinel-4 mission, that will observe Europe in geostationary orbit for air quality monitoring purposes. In general, in the core of O2 A, depending on the optical thickness and altitude of the scatterers, we find RRS-induced in-filling values ranging from 1.3% to 1.8%, while DOLP decreases by 1%. Conversely, while negligible differences of RRS in-filling are calculated with different ice crystal habits, the severely rough aggregated column model can reduce DOLP by a factor up to 10%. The UVN maps of in-filling show values varying

Elimination of polarity in the carotenoid terminus promotes the exposure of B850-binding sites (Tyr 44, 45) and ANS-mediated energy transfer in LH2 complexes of Rhodobacter sphaeroides.

Science.gov (United States)

Liu, Yuan; Wu, Yongqiang; Xu, Chunhe

2004-12-10

Carotenoids in the peripheral light-harvesting complexes (LH2) of the green mutant (GM309) of Rhodobacter sphaeroides were identified as containing neurosporenes, which lack the polar CH(3)O group, compared to spheroidenes in native-LH2 of R. sphaeroides 601. After LH2 complexes were treated with 1-anilino-8-naphthalene sulfonate (ANS), new energy transfer pathways from ANS or tryptophan to carotenoids were discovered in both native- and GM309-LH2. The carotenoid fluorescence intensity of GM309-LH2 was greater than that of native-LH2 when bound with ANS, suggesting that the elimination of polarity in the neurosporene increases the energy transfer from ANS to carotenoid. The fact that two alpha-tyrosines (alpha-Tyr 44, 45, B850-binding sites) in each alpha-apoprotein of GM309-LH2 were more easily modified than those of native-LH2 by N-acetylimidazole (NAI) indicates that the elimination of polarity in the neurosporene terminus increases the exposure of these sites to solution.

POLARIZED LINE FORMATION IN NON-MONOTONIC VELOCITY FIELDS

Energy Technology Data Exchange (ETDEWEB)

Sampoorna, M.; Nagendra, K. N., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in [Indian Institute of Astrophysics, Koramangala, Bengaluru 560034 (India)

2016-12-10

For a correct interpretation of the observed spectro-polarimetric data from astrophysical objects such as the Sun, it is necessary to solve the polarized line transfer problems taking into account a realistic temperature structure, the dynamical state of the atmosphere, a realistic scattering mechanism (namely, the partial frequency redistribution—PRD), and the magnetic fields. In a recent paper, we studied the effects of monotonic vertical velocity fields on linearly polarized line profiles formed in isothermal atmospheres with and without magnetic fields. However, in general the velocity fields that prevail in dynamical atmospheres of astrophysical objects are non-monotonic. Stellar atmospheres with shocks, multi-component supernova atmospheres, and various kinds of wave motions in solar and stellar atmospheres are examples of non-monotonic velocity fields. Here we present studies on the effect of non-relativistic non-monotonic vertical velocity fields on the linearly polarized line profiles formed in semi-empirical atmospheres. We consider a two-level atom model and PRD scattering mechanism. We solve the polarized transfer equation in the comoving frame (CMF) of the fluid using a polarized accelerated lambda iteration method that has been appropriately modified for the problem at hand. We present numerical tests to validate the CMF method and also discuss the accuracy and numerical instabilities associated with it.

Time Domain Induced Polarization

DEFF Research Database (Denmark)

Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders Vest

2012-01-01

Time-domain-induced polarization has significantly broadened its field of reference during the last decade, from mineral exploration to environmental geophysics, e.g., for clay and peat identification and landfill characterization. Though, insufficient modeling tools have hitherto limited the use...... of time-domaininduced polarization for wider purposes. For these reasons, a new forward code and inversion algorithm have been developed using the full-time decay of the induced polarization response, together with an accurate description of the transmitter waveform and of the receiver transfer function......, to reconstruct the distribution of the Cole-Cole parameters of the earth. The accurate modeling of the transmitter waveform had a strong influence on the forward response, and we showed that the difference between a solution using a step response and a solution using the accurate modeling often is above 100...

Probing the ionization wave packet and recollision dynamics with an elliptically polarized strong laser field in the nondipole regime

Science.gov (United States)

Maurer, J.; Willenberg, B.; Daněk, J.; Mayer, B. W.; Phillips, C. R.; Gallmann, L.; Klaiber, M.; Hatsagortsyan, K. Z.; Keitel, C. H.; Keller, U.

2018-01-01

We explore ionization and rescattering in strong mid-infrared laser fields in the nondipole regime over the full range of polarization ellipticity. In three-dimensional photoelectron momentum distributions (3D PMDs) measured with velocity map imaging spectroscopy, we observe the appearance of a sharp ridge structure along the major polarization axis. Within a certain range of ellipticity, the electrons in this ridge are clearly separated from the two lobes that commonly appear in the PMD with elliptically polarized laser fields. In contrast to the well-known lobes of direct electrons, the sharp ridge is created by Coulomb focusing of the softly recolliding electrons. These ridge electrons are directly related to a counterintuitive shift of the PMD peak opposite to the laser beam propagation direction when the dipole approximation breaks down. The ellipticity-dependent 3D PMDs give access to different ionization and recollision dynamics with appropriate filters in the momentum space. For example, we can extract information about the spread of the initial wave packet and the Coulomb momentum transfer of the rescattering electrons.

Measurement of Polarization Observables in the Electro-Excitation of the Proton to its First Excited State

Energy Technology Data Exchange (ETDEWEB)

Roche, Rikki [Florida State Univ., Tallahassee, FL (United States)

2003-08-01

This thesis reports results from the Thomas Jefferson National Accelerator Facility (Jefferson Lab) Hall A experiment E91-011, which measured double-polarization observables in the pion electroproduction reaction from the proton. Specifically, the experiment measured the recoil proton polarization, polarized response functions, and cross section for the p($\\vec{e}$, e' $\\vec{p}$) π° reaction at a center-of-mass energy centered at W = 1232 MeV--the peak of the Δ(1232) resonance--and at a four-momentum transfer squared of Q² = 1.0 GeV²/c². Both the recoil proton polarization and polarized response function results will be presented in this thesis. Data were collected at Jefferson Lab, located in Newport News, Virginia during the summer of 2000. A 4.53 GeV polarized electron beam was scattered off of a cryogenic hydrogen target. The recoil proton polarization was measured in the Focal Plane Polarimeter (FPP), located in one of the two High Resolution Spectrometers (HRS) in Hall A. A maximum likelihood method was used to determine the polarized response functions directly from the measured polarizations and cross sections. A simultaneous fit of the cross sections, the recoil proton polarizations, and angular distributions of the polarized response functions will provide a determination of individual multipole amplitudes. Some of these multipole amplitudes are related to the concept of proton deformation. Both the recoil proton polarizations and polarized response functions were compared to two phenomenological models: MAID and SAID, which have all free parameters fixed, based on fits to previous world data. The measured helicity dependent observables, which are dominated by imaginary parts of Δ(1232)-resonance excitation multipole amplitudes, agree very well with the two models. The measured helicity independent observables, which are dominated by real parts of background multipole amplitudes, do not agree completely with

Studies of nuclear structure via polarization transfer experiments

International Nuclear Information System (INIS)

Moss, J.M.

1985-01-01

Inelastic scattering and charge exchange reactions at medium energies are discussed. Theoretical treatments of these phenomena based on the Dirac equation are presented. A LAMPF experiment in which polarization observables were employed in the search for collective effects in the nuclear pion field is discussed. This experiment is compared with the EMC (European Muon Collaboration) effect. 37 refs., 11 figs

A FORMALISM FOR COVARIANT POLARIZED RADIATIVE TRANSPORT BY RAY TRACING

International Nuclear Information System (INIS)

Gammie, Charles F.; Leung, Po Kin

2012-01-01

We write down a covariant formalism for polarized radiative transfer appropriate for ray tracing through a turbulent plasma. The polarized radiation field is represented by the polarization tensor (coherency matrix) N αβ ≡ (a α k a* β k ), where a k is a Fourier coefficient for the vector potential. Using Maxwell's equations, the Liouville-Vlasov equation, and the WKB approximation, we show that the transport equation in vacuo is k μ ∇ μ N αβ = 0. We show that this is equivalent to Broderick and Blandford's formalism based on invariant Stokes parameters and a rotation coefficient, and suggest a modification that may reduce truncation error in some situations. Finally, we write down several alternative approaches to integrating the transfer equation.

A treatment of the Zeeman effect using Stokes formalism and its implementation in the Atmospheric Radiative Transfer Simulator (ARTS)

International Nuclear Information System (INIS)

Larsson, Richard; Buehler, Stefan A.; Eriksson, Patrick; Mendrok, Jana

2014-01-01

This paper presents the practical theory that was used to implement the Zeeman effect using Stokes formalism in the Atmospheric Radiative Transfer Simulator (ARTS). ARTS now treats the Zeeman effect in a general manner for several gas species for all polarizations and takes into account variations in both magnetic and atmospheric fields along a full 3D geometry. We present how Zeeman splitting affects polarization in radiative transfer simulations and find that the effect may be large in Earth settings for polarized receivers in limb observing geometry. We find that not taking a spatially varying magnetic field into account can result in absolute errors in the measurement vector of at least 10 K in Earth magnetic field settings. The paper also presents qualitative tests for O 2 lines against previous models (61.15 GHz line) and satellite data from Odin-SMR (487.25 GHz line), and the overall consistency between previous models, satellite data, and the new ARTS Zeeman module seems encouraging. -- Highlights: • We implement the Zeeman effect with Stokes formalism in ARTS. • We give a practical theory for the implementation. • Examples of how the Zeeman effect change RT are presented. • Qualitative Odin-SMR O 2 limb sounding model indicates the Zeeman effect is necessary

APC: A New Code for Atmospheric Polarization Computations

Science.gov (United States)

Korkin, Sergey V.; Lyapustin, Alexei I.; Rozanov, Vladimir V.

2014-01-01

A new polarized radiative transfer code Atmospheric Polarization Computations (APC) is described. The code is based on separation of the diffuse light field into anisotropic and smooth (regular) parts. The anisotropic part is computed analytically. The smooth regular part is computed numerically using the discrete ordinates method. Vertical stratification of the atmosphere, common types of bidirectional surface reflection and scattering by spherical particles or spheroids are included. A particular consideration is given to computation of the bidirectional polarization distribution function (BPDF) of the waved ocean surface.

Measurement of polarization observables of the associated strangeness production in proton proton interactions

Energy Technology Data Exchange (ETDEWEB)

Hauenstein, F.; Klaja, P. [Forschungszentrum Juelich, Institut fuer Kernphysik, Juelich (Germany); Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen (Germany); Borodina, E.; Dzhygadlo, R.; Gast, W.; Gillitzer, A.; Grzonka, D.; Kilian, K.; Mertens, M.; Roderburg, E.; Roeder, M.; Sefzick, T.; Wintz, P. [Forschungszentrum Juelich, Institut fuer Kernphysik, Juelich (Germany); Clement, H.; Doroshkevich, E.; Ehrhardt, K. [Physikalisches Institut der Universitaet Tuebingen, Tuebingen (Germany); University of Tuebingen, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Eyrich, W.; Kober, L.; Krapp, M. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen (Germany); Jowzaee, S. [Forschungszentrum Juelich, Institut fuer Kernphysik, Juelich (Germany); Jagellonian University, Institute of Physics, Cracow (Poland); Moskal, P.; Smyrski, J. [Jagellonian University, Institute of Physics, Cracow (Poland); Ritman, J. [Forschungszentrum Juelich, Institut fuer Kernphysik, Juelich (Germany); Juelich Aachen Research Alliance, Forces and Matter Experiments (JARA-FAME), Forschungszentrum Juelich, Juelich (Germany); RWTH Aachen, Aachen (Germany); Ruhr-Universitaet Bochum, Experimentalphysik I, Bochum (Germany); Schroeder, W. [Forschungszentrum Juelich, Corporate Development, Juelich (Germany); Wuestner, P. [Zentralinstitut fuer Engineering, Elektronik und Analytik, Juelich (Germany); Collaboration: The COSY-TOF Collaboration

2016-11-15

The Λ polarization, the analyzing power, and the Λ spin transfer coefficient of the reaction pp → pK{sup +} Λ were measured at beam momenta of 2.70 GeV/c and 2.95 GeV/c corresponding to excess energies of 122 MeV and 204 MeV. While the analyzing power and the spin transfer coefficient do not change significantly with the excess energy, the Λ polarization varies strongly and changes its sign. As this is the first measurement of polarization observables below an excess energy of 200 MeV, the change of the sign of the Λ polarization was not observed before. The high statistics of the data (∼ 200 k events for each momentum) enables detailed studies of the dependence of the Λ polarization and the analyzing power on the center-of-mass momentum of the particles. The results of the spin transfer coefficient are in qualitative agreement with the DISTO experiment. The Λ polarization data of 2.95 GeV/c are only conform with the DISTO experiment, while both the 2.70 GeV/c and 2.95 GeV/c data differ strongly from all previous measurements, whether exclusive or inclusive. (orig.)

The Polar Cusp

International Nuclear Information System (INIS)

Holtet, J.A.; Egeland, A.

1985-01-01

The upper atmosphere at high latitudes is often called the ''earth's window to outer space.'' Through various electrodynamic coupling processes, as well as direct transfer of particles, many of the geophysical effects displayed are direct manifestations of phenomena occurring in deep space. The high latitude ionosphere also exerts a feedback on the regions of the magnetosphere and atmosphere to which it is coupled. Of particular interest are the sections of the near space known as the Polar Cusp. A vast portion of the Earth's magnetic field envelope is electrically connected to these regions. This geometry results in a spatial mapping of the magnetospheric processes and a focusing on the ionosphere. In the Polar Cusps, the solar wind plasma also has direct access to the upper atmosphere

Connecting polar research to NGSS STEM classroom lessons

Science.gov (United States)

Brinker, R.; Kast, D.

2016-12-01

Next Generation Science Standards (NGSS) are designed to bring consistent, rigorous science teaching across the United States. Topics are categorized as Performance Expectations (PE), Disciplinary Core Ideas (DCI), Cross-Cutting Concepts (CCC), and Science and Engineering Practices (SEP). NGSS includes a focus on environmental science and climate change across grade levels. Earth and planetary sciences are required at the high school level. Integrating polar science lessons into NGSS classrooms brings relevant, rigorous climate change curriculum across grade levels. Polar science provides opportunities for students to use current data during lessons, conduct their own field work, and collaborate with scientists. Polar science provides a framework of learning that is novel to most students. Inquiry and engagement are high with polar science lessons. Phenomenon related to polar science provide an excellent tool for science teachers to use to engage students in a lesson, stimulate inquiry, and promote critical thinking. When taught effectively, students see the connections between their community, polar regions and climate change, regardless of where on the planet students live. This presentation describes examples of how to effectively implement NGSS lessons by incorporating polar science lessons and field research. Examples of introductory phenomenon and aligned PEs, CCCs, DCIs, and SEPs are given. Suggested student activities, assessments, examples of student work, student research, labs, and PolarTREC fieldwork, use of current science data, and connections to scientists in the field are provided. The goals of the presentation are to give teachers a blueprint to follow when implementing NGSS lessons, and give scientists an understanding of the basics of NGSS so they may be better able to relate their work to U.S. science education and be more effective communicators of their science findings.

A high volume, batch mode {sup 129}Xe polarizer

Energy Technology Data Exchange (ETDEWEB)

Wojna-Pelczar, Anna, E-mail: anna.wojna.pelczar@mail.muni.cz [Central European Institute of Technology, Masaryk University, Brno (Czech Republic); Formerly: Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków (Poland); Pałasz, Tadeusz [Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków (Poland)

2017-06-01

Numerous designs of optical gas polarizers have been proposed, broadening possible applications of the hyperpolarized gases as contrast agents in magnetic resonance imaging. We present a home–made {sup 129}Xe polarizer based on the spin exchange optical pumping method. The polarizer operates under 1 bar of the gas mixture (at the maximum temperature of 160 °C) in a high volume optical cell (5025 cm{sup 3}). Approximately 100 cm{sup 3} of {sup 129}Xe polarized at 1.50±0.37% is produced in a single cycle of polarization. Operation under standard pressure imposes polarization transfer mainly via van der Waals molecules, resulting in the efficient spin exchange between rubidium and {sup 129}Xe atoms. The design, construction and operation of the polarizer are described in details.

Study of the nuclear structure of 3He by means of polarization observables

International Nuclear Information System (INIS)

Weinriefer, Markus

2011-01-01

With the possibility to measure several polarization degrees of freedom in the quasi-elastic electron scattering of 3 He is a new way to access small, but important partial wave contributions (S ' , D-wave) to the 3 He ground state. This gives direct access to a better understanding of the three-body-system. It also opens up a way to directly test the 3 He structure and dynamics. With this information it is possible to test ab initio calculations and to calculate corrections that are needed for different experiments (measurement of G en for example). Modern Faddeev-calculations do not only give a quantitative description of the 3 He ground state. They also give insight in so called spin dependent momentum distributions. A systematic experimental investigation is needed to get a good basis for tests of the theoretical models. A triple-polarization-experiment can give important data in this field. Also with the help of such an experiment one can investigate if polarized 3 He can be used as an effective polarized proton target by the method of ''deuteron-tagging''. The experiment presented in this work combines for the first time beam- and target-polarization as well as a measurement of the polarization of the outgoing proton. The measurement was done in summer of 2007 at the three spectrometer setup of the A1 collaboration at the MAMI accelerator. A beam energy of E=855 MeV was used and we measured at q 2 =-0.14 (GeV/c) 2 (ω=0.13 GeV, q=0.4 GeV/c). The measured cross section, as well as the beam-target- and triple-asymmetry were compared to a theoretical calculation by J. Golak (he gives a plane wave impulse approximation (PWIA) calculation and a calculation also taking final state interaction into account). The cross section was also compared to a model by de Forest that is using a measured spectral function. The comparison shows a good agreement between the measured cross section as well as the double and triple asymmetry and the theoretical calculations. The

Parity non-conservation in the capture of polarized thermal neutrons

DEFF Research Database (Denmark)

Warming, Inge Elisabeth

1969-01-01

The asymmetry in the intensity of γ-radiation following the capture of polarized thermal neutrons in 113Cd has been measured with Ge(Li) detectors. The result, A = (−0.6±1.8)×10−4, like that previously reported [1], gives no evidence for a non-zero effect.......The asymmetry in the intensity of γ-radiation following the capture of polarized thermal neutrons in 113Cd has been measured with Ge(Li) detectors. The result, A = (−0.6±1.8)×10−4, like that previously reported [1], gives no evidence for a non-zero effect....

Ground-based Polarization Remote Sensing of Atmospheric Aerosols and the Correlation between Polarization Degree and PM2.5

International Nuclear Information System (INIS)

Cheng, Chen; Zhengqiang, Li; Weizhen, Hou; Yisong, Xie; Donghui, Li; Kaitao, Li; Ying, Zhang

2014-01-01

The ground-based polarization remote sensing adds the polarization dimension information to traditional intensity detection, which provides a new method to detect atmospheric aerosols properties. In this paper, the polarization measurements achieved by a new multi-wavelength sun photometer, CE318-DP, are used for the ground-based remote sensing of atmospheric aerosols. In addition, a polarized vector radiative transfer model is introduced to simulate the DOLP (Degree Of Linear Polarization) under different sky conditions. At last, the correlative analysis between mass density of PM 2.5 and multi-wavelength and multi-angular DOLP is carried out. The result shows that DOLP has a high correlation with mass density of PM 2.5 , R 2 >0.85. As a consequence, this work provides a new method to estimate the mass density of PM 2.5 by using the comprehensive network of ground-based sun photometer

[The Effect of Observation Geometry on Polarized Skylight Spectrum].

Science.gov (United States)

Zhang, Ren-bin; Wang, Ling-mei; Gao, Jun; Wang, Chi

2015-03-01

Study on polarized skylight spectral characters while observation geometry changing in different solar zenith angles (SZA), viewing zenith angles (VZA) or relative azimuth angles (RAA). Simulation calculation of cloudless daylight polarimetric spectrum is realized based on the solver, vector discrete ordinate method, of radiative transfer equation. In the Sun's principal and perpendicular plane, the spectral irradiance data, varying at wavelengths in the range between 0.4 and 3 μm, are calculated to extend the atmospheric polarization spectral information under the conditions: the MODTRAN solar reference spectrur is the only illuminant source; the main influencing factors of polarized radiative transfer include underlying surface albedo, aerosol layers and components, and the absorption of trace gases. Simulation analysis results: (1) While the relative azimuth angle is zero, the magnitude of spectrum U/I is lower than 10(-7) and V/I is negligible, the degree of polarization and the spectrum Q/I are shaped like the letter V or mirror-writing U. (2) In twilight, when the Sun is not in FOV of the detector, the polarization of the daytime sky has two maximum near 0.51 and 2.75 μm, and a minimum near 1.5 μm. For arbitrary observation geometry, the spectral signal of V/I may be ignored. According to observation geometry, choosing different spectral bands or polarized signal will be propitious to targets detection.

Magnetoresistance through spin-polarized p states

International Nuclear Information System (INIS)

Papanikolaou, Nikos

2003-01-01

We present a theoretical study of the ballistic magnetoresistance in Ni contacts using first-principles, atomistic, electronic structure calculations. In particular we investigate the role of defects in the contact region with the aim of explaining the recently observed spectacular magnetoresistance ratio. Our results predict that the possible presence of spin-polarized oxygen in the contact region could explain conductance changes by an order of magnitude. Electronic transport essentially occurs through spin-polarized oxygen p states, and this mechanism gives a much higher magnetoresistance than that obtained assuming clean atomically sharp domain walls alone

Radially Polarized Conical Beam from an Embedded Etched Fiber

OpenAIRE

Kalaidji , D.; Spajer , M.; Marthouret , N.; Grosjean , T.

2009-01-01

International audience; We propose a method for producing a conical beam based on the lateral refraction of the TM01 mode from a two-mode fiber after chemical etching of the cladding, and for controlling its radial polarization. The whole power of the guided mode is transferred to the refracted beam with low diffraction. Polarization control by a series of azimuthal detectors and a stress controller affords the transmission of a stabilized radial polarization through an optical fiber. A solid...

Refrigeration. Heat Transfer. Part I: Evaporators and Condensers

DEFF Research Database (Denmark)

Knudsen, Hans-Jørgen Høgaard

2002-01-01

The note gives an introduction to heat transfer with phase shift. Pool Boiling, Flow Boiling, Condensation.......The note gives an introduction to heat transfer with phase shift. Pool Boiling, Flow Boiling, Condensation....

Dynamical nuclear polarization using multi-colour control of color centers in diamond

Energy Technology Data Exchange (ETDEWEB)

Yang, Pengcheng [Huazhong University of Science and Technology, School of Physics, Wuhan (China); Huazhong University of Science and Technology, Center for Quantum Optical Science, Wuhan (China); Plenio, Martin B. [Universitaet Ulm, Institut fuer Theoretische Physik, Ulm (Germany); Universitaet Ulm, Center for Integrated Quantum Science and Technology, Ulm (Germany); Cai, Jianming [Huazhong University of Science and Technology, School of Physics, Wuhan (China); Huazhong University of Science and Technology, Center for Quantum Optical Science, Wuhan (China); Universitaet Ulm, Institut fuer Theoretische Physik, Ulm (Germany); Universitaet Ulm, Center for Integrated Quantum Science and Technology, Ulm (Germany)

2016-12-15

Dynamical nuclear polarization (DNP) transfers the polarization of electron spins at cryogenic temperatures to achieve strong nuclear polarization for applications in nuclear magnetic resonance. Recently introduced approaches employ optical pumping of nitrogen-vacancy (NV) centers in diamond to achieve DNP even at ambient temperatures. In such schemes microwave radiation is used to establish a Hartmann-Hahn condition between the NV electron spin and proximal nuclear spins to facilitate polarization transfer. For a single monochromatic microwave driving field, the Hartmann-Hahn condition cannot be satisfied for an ensemble of NV centers due to inhomogeneous broadening and reduces significantly the overall efficiency of dynamical nuclear polarization using an ensemble of NV centers. Here, we adopt generalized Hartmann-Hahn type dynamical nuclear polarization schemes by applying microwave driving fields with (multiple) time-modulated frequencies. We show that it is possible to enhance the effective coupling between an ensemble of NV center spins with inhomogeneous broadening and nuclear spins, thereby improving significantly the overall efficiency of dynamical nuclear polarization. This approach can also be used to achieve dynamical nuclear polarization of an ensemble of nuclei with a distribution of Larmor frequencies, which would be helpful in magnetic resonance spectroscopy using a single NV spin sensor. (orig.)

High-efficiency transmision neutron polarizer for high-resolution double crystal diffractometer

International Nuclear Information System (INIS)

Ioffe, A.; Krist, T.; Mezei, F.; Gordeev, G.; Ibrayev, B.

1997-01-01

An efficient transmission geometry neutron polarizer for the high-resolution double crystal diffractometer at HMI (λ=4.8 A) is described. A polarization of about 94% was achieved and the polarized neutron beam intensity amounts to 40% of the nonpolarized beam intensity. This opens up wide possibilities for the study of magnetic small-angle scattering for extremely small momentum transfer (Q∝10 -5 A -1 ). (orig.)

Interfacial polarization phenomena in organic molecular films

International Nuclear Information System (INIS)

Iwamoto, Mitsumasa; Manaka, Takaaki

2006-01-01

Electrostatic phenomena occurring at the interface between metal/organic and organic/organic materials are discussed from the viewpoint of dielectrics physics. Focusing on two important origins of surface polarization phenomena, orientational ordering of polar molecules and displacement of excess charges at the interface, surface polarization phenomena of organic thin films are discussed. To define the orientational order of polar molecules, orientational order parameters are introduced, and surface polarization due to the alignment of dipoles is expressed. The generation of Maxwell displacement current (MDC) and optical second harmonic generation (SHG) that are specific for surface organic monomolecular films are discussed, and some experimental evidence are shown. As an extension of the concept of surface Fermi level introduced to discuss the electrostatic phenomena due to electron transfer at the interface between metal-organic insulators, the surface Fermi level is extended to the discussion on the electrostatic phenomena of organic semiconductor materials on metals. In this paper, some experimental evidence of surface polarization originating from polar molecules and displacement of excess charges are shown. After that, with consideration of these surface phenomena, single electron tunneling of organic films are briefly discussed in association with surface polarization phenomena

Strategic Polarization.

Science.gov (United States)

Kalai, Adam; Kalai, Ehud

2001-08-01

In joint decision making, similarly minded people may take opposite positions. Consider the example of a marriage in which one spouse gives generously to charity while the other donates nothing. Such "polarization" may misrepresent what is, in actuality, a small discrepancy in preferences. It may be that the donating spouse would like to see 10% of their combined income go to charity each year, while the apparently frugal spouse would like to see 8% donated. A simple game-theoretic analysis suggests that the spouses will end up donating 10% and 0%, respectively. By generalizing this argument to a larger class of games, we provide strategic justification for polarization in many situations such as debates, shared living accommodations, and disciplining children. In some of these examples, an arbitrarily small disagreement in preferences leads to an arbitrarily large loss in utility for all participants. Such small disagreements may also destabilize what, from game-theoretic point of view, is a very stable equilibrium. Copyright 2001 Academic Press.

Scattering of polarized low-energy electrons by ferromagnetic metals

International Nuclear Information System (INIS)

Helman, J.S.

1981-01-01

A source of spin polarized electrons with remarkable characteristics based on negative electron affinity (NEA) GaAs has recently been developed. It constitutes a unique tool to investigate spin dependent interactions in electron scattering processes. The characteristics and working principles of the source are briefly described. Some theoretical aspects of the scattering of polarized low-energy electrons by ferromagnetic metals are discussed. Finally, the results of the first polarized low-energy electron diffraction experiment using the NEA GaAs source are reviewed; they give information about the surface magnetization of ferromagnetic Ni (110). (Author) [pt

Effect of anode polarization on biofilm formation and electron transfer in Shewanella oneidensis/graphite felt microbial fuel cells.

Science.gov (United States)

Pinto, David; Coradin, Thibaud; Laberty-Robert, Christel

2018-04-01

In microbial fuel cells, electricity generation is assumed by bacterial degradation of low-grade organics generating electrons that are transferred to an electrode. The nature and efficiency of the electron transfer from the bacteria to the electrodes are determined by several chemical, physical and biological parameters. Specifically, the application of a specific potential at the bioanode has been shown to stimulate the formation of an electro-active biofilm, but the underlying mechanisms remain poorly understood. In this study, we have investigated the effect of an applied potential on the formation and electroactivity of biofilms established by Shewanella oneidensis bacteria on graphite felt electrodes in single- and double-chamber reactor configurations in oxic conditions. Using amperometry, cyclic voltammetry, and OCP/Power/Polarization curves techniques, we showed that a potential ranging between -0.3V and +0.5V (vs. Ag/AgCl/KCl sat.) and its converse application to a couple of electrodes leads to different electrochemical behaviors, anodic currents and biofilm architectures. For example, when the bacteria were confined in the anodic compartment of a double-chamber cell, a negative applied potential (-0.3V) at the bioanode favors a mediated electron transfer correlated with the progressive formation of a biofilm that fills the felt porosity and bridges the graphite fibers. In contrast, a positive applied potential (+0.3V) at the bioanode stimulates a direct electron transfer resulting in the fast-bacterial colonization of the fibers only. These results provide significant insight for the understanding of the complex bacteria-electrode interactions in microbial fuel cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Polar bears, Ursus maritimus

Science.gov (United States)

Rode, Karyn D.; Stirling, Ian

2017-01-01

Polar bears are the largest of the eight species of bears found worldwide and are covered in a pigment-free fur giving them the appearance of being white. They are the most carnivorous of bear species consuming a high-fat diet, primarily of ice-associated seals and other marine mammals. They range throughout the circumpolar Arctic to the southernmost extent of seasonal pack ice.

Spin-isospin excitations studied by polarized beams

International Nuclear Information System (INIS)

Sakai, H.; Greenfield, M.B.; Hatanaka, K.

1996-01-01

The spin-parity J π of the spin dipole resonances (SDR) in 12 N and 12 B are investigated via the measurements of polarization observables, the transverse polarization transfer coefficient D NN for the (vector p, vector n) reaction at 197 and 295 MeV and the tensor analyzing power A xx for the (vector d, 2 He) reaction at 270 MeV. The polarization observables, D NN and A xx for the peak at 4.5 MeV are consistent with the DWIA prediction with 2 - but those for the peak at 7.5 MeV contradict the predictions with an expected J π =1 - . Neither polarization observables could detect any concentration of 0 - strength. The usefulness of these spin observables in identifying J π is shown. (orig.)

Spin polarized electron source technology transferred from HE accelerators to electron microscopes

International Nuclear Information System (INIS)

Nakanishi, Tsutomu

2009-01-01

For many years, we have developed a technology of spin-polarized-electron-source (PES) for a future linear collider project (ILC). Various new techniques for achieving high polarization, high quantum efficiency, high current density, sub-nanosecond multi-bunch generation etc. were developed. Two fundamental technologies; reduction of dark current and preparation of extremely high vacuum environment to protect the Negative Electron Affinity (NEA) surface have been also developed. Using these PES technologies and a new transmission type photocathode, we recently succeeded in producing the high brightness and high polarization electron beam for the low energy electron microscope (LEEM). Our Spin-LEEM system enables the world-first dynamic observation of surface magnetic domain formed by evaporation on the metal substrate with ∼ 20 nm space resolutions. (author)

Radially polarized conical beam from an embedded etched fiber.

Science.gov (United States)

Kalaidji, Djamel; Spajer, Michel; Marthouret, Nadège; Grosjean, Thierry

2009-06-15

We propose a method for producing a conical beam based on the lateral refraction of the TM(01) mode from a two-mode fiber after chemical etching of the cladding, and for controlling its radial polarization. The whole power of the guided mode is transferred to the refracted beam with low diffraction. Polarization control by a series of azimuthal detectors and a stress controller affords the transmission of a stabilized radial polarization through an optical fiber. A solid component usable for many applications has been obtained.

Deterministic and stochastic methods of calculation of polarization characteristics of radiation in natural environment

Science.gov (United States)

Strelkov, S. A.; Sushkevich, T. A.; Maksakova, S. V.

2017-11-01

We are talking about russian achievements of the world level in the theory of radiation transfer, taking into account its polarization in natural media and the current scientific potential developing in Russia, which adequately provides the methodological basis for theoretically-calculated research of radiation processes and radiation fields in natural media using supercomputers and mass parallelism. A new version of the matrix transfer operator is proposed for solving problems of polarized radiation transfer in heterogeneous media by the method of influence functions, when deterministic and stochastic methods can be combined.

What can we learn from unpolarized and polarized electroproduction of fast baryons

International Nuclear Information System (INIS)

Artru, X.

1991-01-01

Two applications of semi-inclusive electroproduction of fast baryons are presented: (i) The steepness of the baryon spectrum at medium rapidity can give information about the general mechanisms of baryon production in soft and hard processes. (ii) With a polarized target and a detector which analyses the polarization of final Λ's, the aptitude of quarks to carry transverse polarization can be tested for the first time

Polarization of Coronal Forbidden Lines

Energy Technology Data Exchange (ETDEWEB)

Li, Hao; Qu, Zhongquan [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China); Landi Degl’Innocenti, Egidio, E-mail: sayahoro@ynao.ac.cn [Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Largo E. Fermi 2, I-50125 Firenze (Italy)

2017-03-20

Since the magnetic field is responsible for most manifestations of solar activity, one of the most challenging problems in solar physics is the diagnostics of solar magnetic fields, particularly in the outer atmosphere. To this end, it is important to develop rigorous diagnostic tools to interpret polarimetric observations in suitable spectral lines. This paper is devoted to analyzing the diagnostic content of linear polarization imaging observations in coronal forbidden lines. Although this technique is restricted to off-limb observations, it represents a significant tool to diagnose the magnetic field structure in the solar corona, where the magnetic field is intrinsically weak and still poorly known. We adopt the quantum theory of polarized line formation developed in the framework of the density matrix formalism, and synthesize images of the emergent linear polarization signal in coronal forbidden lines using potential-field source-surface magnetic field models. The influence of electronic collisions, active regions, and Thomson scattering on the linear polarization of coronal forbidden lines is also examined. It is found that active regions and Thomson scattering are capable of conspicuously influencing the orientation of the linear polarization. These effects have to be carefully taken into account to increase the accuracy of the field diagnostics. We also found that linear polarization observation in suitable lines can give valuable information on the long-term evolution of the magnetic field in the solar corona.

Polarized ionic source of the tandem accelerator in Kyoto University

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Masanobu; Kuwamoto, Shuichi; Takahashi, Seiji [Kyoto Univ. (Japan). Dept. of Physics] [and others

1997-02-01

A polarized ion source developed under the National Laboratory of High Energy Physics was transferred to the tandem accelerator in Kyoto University at beginning of 1993 to constitute a displacement of incidence into the accelerator. This was an atomic beam type polarized ion source, which is designed to adopt permanent magnets for 6 poles magnet to polarize the electron, to take out atomic nucleus on a shape of positive ion by ECR ionizer after transferring its polarization through transition using radio frequency (RFT), to make it negative ion by charge conversion using alkaline metal vapor, and to put it into the tandem accelerator. Test of the positive ion was finished at the National Laboratory of High Energy Physics, and test in Kyoto University was required after its negative ionization. As the estimated cost was unsufficient and entrance into the ion source facility in the tandem accelerator building was limited in Kyoto University, step of development was slow. Here is reported on present state of the ion source which is now operating stably. (G.K.)

Polarization versus Temperature in Pyridinium Ionic Liquids

DEFF Research Database (Denmark)

Chaban, V. V.; Prezhdo, O. V.

2014-01-01

Electronic polarization and charge transfer effects play a crucial role in thermodynamic, structural, and transport properties of room-temperature ionic liquids (RTILs). These nonadditive interactions constitute a useful tool for tuning physical chemical behavior of RTILs. Polarization and charge...... interactions changes negligibly between 300 and 900 K, while the average dipole moment increases due to thermal fluctuations of geometries. Our results contribute to the fundamental understanding of electronic effects in the condensed phase of ionic systems and foster progress in physical chemistry...

Voltammetry of ion transfer across a polarized room-temperature ionic liquid membrane facilitated by valinomycin: theoretical aspects and application.

Science.gov (United States)

Langmaier, Jan; Samec, Zdenek

2009-08-01

Cyclic voltammetry is used to investigate the transfer of alkali-metal cations, protons, and ammonium ions facilitated by the complex formation with valinomycin at the interface between an aqueous electrolyte solution and a room-temperature ionic liquid (RTIL) membrane. The membrane is made of a thin (approximately 112 microm) microporous filter impregnated with an RTIL that is composed of tridodecylmethylammonium cations and tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anions. An extension of the existing theory of voltammetry of ion transfer across polarized liquid membranes makes it possible to evaluate the standard ion-transfer potentials for the hydrophilic cations studied, as well as the stability constants (K(i)) of their 1:1 complexes with valinomycin, as log K(i) = 9.0 (H(+)), 11.1 (Li(+)), 12.8 (Na(+)), 17.2 (K(+)), 15.7 (Rb(+)), 15.1 (Cs(+)), and 14.7 (NH(4)(+)). These data point to the remarkably enhanced stability of the valinomycin complexes within RTIL, and to the enhanced selectivity of valinomycin for K(+) over all other univalent ions studied, compared to the conventional K(+) ion-selective liquid-membrane electrodes. Selective complex formation allows one to resolve voltammetric responses of K(+) and Na(+) in the presence of an excess of Mg(2+) or Ca(2+), which is demonstrated by determination of K(+) and Na(+) in the table and tap water samples.

Vacuum polarization and renormalized charge in ν-dimensions

International Nuclear Information System (INIS)

Marinho Junior, R.M.; Lucinda, J.

1984-01-01

The expression for the vacuum polarization is obtained for any momentum transfer in ν dimensions. Using the Wilson loop for QED, the renormalized electric charge in ν dimensions is calculated. (Author) [pt

Calibration of the degree of linear polarization measurements of the polarized Sun-sky radiometer based on the POLBOX system.

Science.gov (United States)

Li, Zhengqiang; Li, Kaitao; Li, Li; Xu, Hua; Xie, Yisong; Ma, Yan; Li, Donghui; Goloub, Philippe; Yuan, Yinlin; Zheng, Xiaobing

2018-02-10

Polarization observation of sky radiation is the frontier approach to improve the remote sensing of atmospheric components, e.g., aerosol and clouds. The polarization calibration of the ground-based Sun-sky radiometer is the basis for obtaining accurate degree of linear polarization (DOLP) measurement. In this paper, a DOLP calibration method based on a laboratory polarized light source (POLBOX) is introduced in detail. Combined with the CE318-DP Sun-sky polarized radiometer, a calibration scheme for DOLP measurement is established for the spectral range of 440-1640 nm. Based on the calibration results of the Sun-sky radiometer observation network, the polarization calibration coefficient and the DOLP calibration residual are analyzed statistically. The results show that the DOLP residual of the calibration scheme is about 0.0012, and thus it can be estimated that the final DOLP calibration accuracy of this method is about 0.005. Finally, it is verified that the accuracy of the calibration results is in accordance with the expected results by comparing the simulated DOLP with the vector radiative transfer calculations.

A method to calculate Stokes parameters and angle of polarization of skylight from polarized CIMEL sun/sky radiometers

International Nuclear Information System (INIS)

Li, L.; Li, Z.; Li, K.; Blarel, L.; Wendisch, M.

2014-01-01

The polarized CIMEL sun/sky radiometers have been routinely operated within the Sun/sky-radiometer Observation NETwork (SONET) in China and some sites of the AErosol RObotic NETwork (AERONET) around the world. However, the polarization measurements are not yet widely used due to in a certain degree the lack of Stokes parameters derived directly from these polarization measurements. Meanwhile, it have been shown that retrievals of several microphysical properties of aerosol particles can be significantly improved by using degree of linear polarization (DoLP) measurements of polarized CIMEL sun/sky radiometers (CE318-DP). The Stokes parameters Q and U, as well as angle of polarization (AoP) contain additional information about linear polarization and its orientation. A method to calculate Stokes parameters Q, U, and AoP from CE318-DP polarized skylight measurements is introduced in this study. A new polarized almucantar geometry based on CE318-DP is measured to illustrate abundant variation features of these parameters. The polarization parameters calculated in this study are consistent with previous results of DoLP and I, and also comparable to vector radiative transfer simulations. - Highlights: • The CE318-DP polarized measurements are not yet widely used except DoLP. • Compared with DoLP and I, difficulty in calculating Stokes Q and U is discussed. • A new polarized almucantar observation geometry based on CE318-DP is executed. • We derive Stokes Q, U, and AoP both in principal and almucantar plane geometries. • The results are comparable with previous DoLP and I, as well as model simulations

What can we learn from unpolarized and polarized electroproduction of fast baryons?

International Nuclear Information System (INIS)

Artru, X.; Mekhfi, M.

1991-01-01

Two applications of semi-inclusive electroproduction of fast baryons are presented: (i) The steepness of the baryon spectrum at medium rapidity can give information about the general mechanisms of baryon production in soft and hard processes. (ii) With a polarized target and a detector which analyses the polarization of final Λ's, the aptitude of quarks to carry transverse polarization can be tested for the first time. (orig.)

Attosecond polarization control in atomic RABBITT-like experiments assisted by a circularly polarized laser

Science.gov (United States)

Boll, D. I. R.; Fojón, O. A.

2017-12-01

We study theoretically the single ionization of noble gas atoms by the combined action of an attosecond pulse train with linear polarization and an assistant laser field with circular polarization. We employ a non-perturbative model that under certain approximations gives closed-form expressions for the angular distributions of photoelectrons. Interestingly, our model allow us to interpret these angular distributions as two-centre interferences where the orientation and the modulus of the separation vector between the virtual emitters is governed by the assistant laser field. Additionally, we show that such a configuration of light fields is similar to the polarization control technique, where both the attosecond pulse train and the assistant laser field have linear polarizations whose relative orientation may be controlled. Moreover, in order to compare our results with the available experimental data, we obtain analytical expressions for the cross sections integrated over the photoelectron emission angles. By means of these expressions, we define the ‘magic time’ as the delay for which the total cross sections for atomic targets exhibit the same functional form as the one of the monochromatic photoionization of diatomic molecular targets.

Asymptotic theory of circular polarization memory.

Science.gov (United States)

Dark, Julia P; Kim, Arnold D

2017-09-01

We establish a quantitative theory of circular polarization memory, which is the unexpected persistence of the incident circular polarization state in a strongly scattering medium. Using an asymptotic analysis of the three-dimensional vector radiative transfer equation (VRTE) in the limit of strong scattering, we find that circular polarization memory must occur in a boundary layer near the portion of the boundary on which polarized light is incident. The boundary layer solution satisfies a one-dimensional conservative scattering VRTE. Through a spectral analysis of this boundary layer problem, we introduce the dominant mode, which is the slowest-decaying mode in the boundary layer. To observe circular polarization memory for a particular set of optical parameters, we find that this dominant mode must pass three tests: (1) this dominant mode is given by the largest, discrete eigenvalue of a reduced problem that corresponds to Fourier mode k=0 in the azimuthal angle, and depends only on Stokes parameters U and V; (2) the polarization state of this dominant mode is largely circular polarized so that |V|≫|U|; and (3) the circular polarization of this dominant mode is maintained for all directions so that V is sign-definite. By applying these three tests to numerical calculations for monodisperse distributions of Mie scatterers, we determine the values of the size and relative refractive index when circular polarization memory occurs. In addition, we identify a reduced, scalar-like problem that provides an accurate approximation for the dominant mode when circular polarization memory occurs.

Efficient ionizer for polarized H- formation

International Nuclear Information System (INIS)

Alessi, J.G.

1985-01-01

An ionizer is under development for a polarized H - source based on the resonant charge exchange reaction polarized H 0 + D - → polarized H - + D 0 . The polarized H 0 beam passes through the center of a magnetron surface-plasma source having an annular geometry, where it crosses a high current (approx.0.5 A), 200 eV D - beam. Calculations predict an H 0 → H - ionization efficiency of approx.7%, more than an order of magnitude higher than that obtained on present ground state atomic beam sources. In initial experiments using an unpolarized H 0 beam, H - currents in excess of 100 μA have been measured. While the ionization efficiency is now only about the same as other methods (Cs beam, for example), the results are encouraging since it appears that by injecting positive ions to improve the space-charge neutralization, and by improving the extraction optics, considerable gains in intensity will be made. We will then use this ionizer with a polarized H 0 beam, and measure the polarization of the resulting H - beam. If no depolarization is observed this ionizer will be combined with an atomic beam, cooled to 5 to 6 K, to give a polarized H - beam expected to be in the milliampere range for use in the AGS

A 1.5--4 Kelvin detachable cold-sample transfer system: Application to inertially confined fusion with spin-polarized hydrogens fuels

International Nuclear Information System (INIS)

Alexander, N.; Barden, J.; Fan, Q.; Honig, A.

1990-01-01

A compact cold-transfer apparatus for engaging and retrieving samples at liquid helium temperatures (1.5--4K), maintaining the samples at such temperatures for periods of hours, and subsequently inserting them in diverse apparatuses followed by disengagement, is described. The properties of several thermal radiation-insulating shrouds, necessary for very low sample temperatures, are presented. The immediate intended application is transportable target-shells containing highly spin-polarized deuterons in solid HD or D 2 for inertially confined fusion (ICF) experiments. The system is also valuable for unpolarized high-density fusion fuels, as well as for other applications which are discussed. 9 refs., 6 figs

Fusion with highly spin polarized HD and D2

International Nuclear Information System (INIS)

Honig, A.; Letzring, S.; Skupsky, S.

1993-01-01

The experimental efforts over the past 5 years have been aimed at carrying out ICF shots with spin-polarized D fuel. The authors successfully prepared polarized D in HD, and solved the problems of loading target shells with their carefully prepared isotopic mixtures, polarizing them so that the D polarization remains metastably frozen-in for about half a day, and carrying out the various cold transfer requirements at Syracuse, where the target is prepared, and at Rochester, where the cold target is inserted into the OMEGA fusion chamber. A principal concern during this past year was overcoming difficulties encountered in maintaining the integrity of the fragile cold target during the multitude of cold-transfers required for the experiment. These difficulties arose from insufficient rigidity of the cold transfer systems, which were constrained to be of small diameter by the narrow central access bore of the dilution refrigerator, and were exacerbated by the multitude of required target shell manipulations between different environments, each with different coupling geometry, including target shell permeation, polarization, storage, transport, retrieval and insertion into OMEGA. The authors did solve all of these problems, and were able to position a cold, high density but unpolarized target with required precision in OMEGA. Upon shooting the accurately positioned unpolarized high density cold target, no neutron yield was observed. Inspection inside the OMEGA tank after the shot indicated the absence of neutron yield was due to mal-timing or insufficient retraction rate of OMEGA's fast shroud mechanism, resulting in interception of at least 20 of the 24 laser beams by the faulty shroud. In spite of this, all elements of the complex experiment the authors originally undertook have been successfully demonstrated, and the cold retrieval concepts and methods they developed are being utilized on the ICF upgrades at Rochester and at Livermore

Give and Take in Dictator Games

DEFF Research Database (Denmark)

Cappelen, Alexander W.; Nielsen, Ulrik Haagen; Sørensen, Erik Ø.

2014-01-01

It has been shown that participants in the dictator game are less willing to give money to the other participant when their choice set also includes the option to take money. We examine whether this effect is due to the choice set providing a signal about entitlements in a setting where...... entitlements initially may be considered unclear. We find that the share of positive transfers depends on the choice set even when there is no uncertainty about entitlements, and that this choice-set effect is robust across a heterogenous group of participants recruited from the general adult population...

Conversion of polar and non-polar algae oil lipids to fatty acid methyl esters with solid acid catalysts--A model compound study.

Science.gov (United States)

Asikainen, Martta; Munter, Tony; Linnekoski, Juha

2015-09-01

Bio-based fuels are becoming more and more important due to the depleting fossil resources. The production of biodiesel from algae oil is challenging compared to terrestrial vegetable oils, as algae oil consists of polar fatty acids, such as phospholipids and glycolipids, as well as non-polar triglycerides and free fatty acids common in vegetable oils. It is shown that a single sulphonated solid acid catalyst can perform the esterification and transesterification reactions of both polar and non-polar lipids. In mild reaction conditions (60-70 °C) Nafion NR50 catalyst produces methyl palmitate (FAME) from the palmitic acid derivatives of di-, and tri-glyceride, free fatty acid, and phospholipid with over 80% yields, with the glycolipid derivative giving nearly 40% yields of FAME. These results demonstrate how the polar and non-polar lipid derivatives of algal oil can be utilised as feedstocks for biodiesel production with a single catalyst in one reaction step. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fast, High-Precision Optical Polarization Synthesizer for Ultracold-Atom Experiments

Science.gov (United States)

Robens, Carsten; Brakhane, Stefan; Alt, Wolfgang; Meschede, Dieter; Zopes, Jonathan; Alberti, Andrea

2018-03-01

We present a technique for the precision synthesis of arbitrary polarization states of light with a high modulation bandwidth. Our approach consists of superimposing two laser light fields with the same wavelength, but with opposite circular polarizations, where the phase and the amplitude of each light field are individually controlled. We find that the polarization-synthesized beam reaches a degree of polarization of 99.99%, which is mainly limited by static spatial variations of the polarization state over the beam profile. We also find that the depolarization caused by temporal fluctuations of the polarization state is about 2 orders of magnitude smaller. In a recent work, Robens et al. [Low-Entropy States of Neutral Atoms in Polarization-Synthesized Optical Lattices, Phys. Rev. Lett. 118, 065302 (2017), 10.1103/PhysRevLett.118.065302] demonstrated an application of the polarization synthesizer to create two independently controllable optical lattices which trap atoms depending on their internal spin state. We use ultracold atoms in polarization-synthesized optical lattices to give an independent, in situ demonstration of the performance of the polarization synthesizer.

Current-induced spin transfer torque in ferromagnet-marginal Fermi liquid double tunnel junctions

International Nuclear Information System (INIS)

Mu Haifeng; Zheng Qingrong; Jin Biao; Su Gang

2005-01-01

Current-induced spin transfer torque through a marginal Fermi liquid (MFL) which is connected to two noncollinearly aligned ferromagnets via tunnel junctions is discussed in terms of the nonequilibrium Green function method. It is found that in the absence of the spin-flip scattering, the magnitude of the torque increases with the polarization and the coupling constant λ of the MFL, whose maximum increases with λ linearly, showing that the interactions between electrons tend to enhance the spin torque. When the spin-flip scattering is included, an additional spin torque is induced. It is found that the spin-flip scattering enhances the spin torque and gives rise to a nonlinear angular shift

Spin-polarized photoemission from SiGe heterostructures

Energy Technology Data Exchange (ETDEWEB)

Ferrari, A.; Bottegoni, F.; Isella, G.; Cecchi, S.; Chrastina, D.; Finazzi, M.; Ciccacci, F. [LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

2013-12-04

We apply the principles of Optical Orientation to measure by Mott polarimetry the spin polarization of electrons photoemitted from different group-IV heterostructures. The maximum measured spin polarization, obtained from a Ge/Si{sub 0.31}Ge{sub 0.69} strained film, undoubtedly exceeds the maximum value of 50% attainable in bulk structures. The explanation we give for this result lies in the enhanced band orbital mixing between light hole and split-off valence bands as a consequence of the compressive strain experienced by the thin Ge layer.

Scattering Polarization in Solar Flares

Czech Academy of Sciences Publication Activity Database

Štěpán, Jiří; Heinzel, Petr

2013-01-01

Roč. 778, č. 1 (2013), L6/1-L6/6 ISSN 2041-8205 R&D Projects: GA ČR GAP209/12/1652; GA ČR GPP209/12/P741 Institutional support: RVO:67985815 Keywords : line formation * polarization * radiative transfer Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.602, year: 2013

One photon exchange processes and the calibration of polarization of high energy protons

International Nuclear Information System (INIS)

Margolis, B.; Thomas, G.H.

1978-01-01

Polarization phenomena in small momentum transfer high energy one-photon exchange processes in the reaction p + A → X + A where A is a complex nucleus and X is anything are examined. It is shown that these polarizations can be related directly to photoproduction polarization effects in the reaction γ + p → X at low energies. Explicit formulae are written for polarization effects in the case where X → π 0 + p

Metamaterial polarization converter analysis: limits of performance

DEFF Research Database (Denmark)

Markovich, Dmitry L.; Andryieuski, Andrei; Zalkovskij, Maksim

2013-01-01

and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design......In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed...... level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter...

Effect of atomic noise on optical squeezing via polarization self-rotation in a thermal vapor cell

DEFF Research Database (Denmark)

Hsu, M.T.L.; Hetet, G.; Peng, A.

2006-01-01

The traversal of an elliptically polarized optical field through a thermal vapor cell can give rise to a rotation of its polarization axis. This process, known as polarization self-rotation (PSR), has been suggested as a mechanism for producing squeezed light at atomic transition wavelengths. We ...

Cross section and linear polarization of tagged photons

International Nuclear Information System (INIS)

Asai, J.; Caplan, H.S.; Skopik, D.M.; DelBianco, W.; Maximon, L.C.

1988-01-01

Formulae for bremsstrahlung cross sections and polarizations are usually presented in coordinate systems not very suitable for application by experimental physicists to devices such as photon-tagging monochromators. In this paper the transformations between the different coordinate systems are presented, along with examples of the calculated cross sections and polarizations in a form convenient from the experimental standpoint. These examples also give the predicted characteristics of the photon tagger currently under construction at the Saskatchewan Accelerator Laboratory. (16 refs., 19 figs., tab.)

Probing Quark-Gluon Interactions with Transverse Polarized Scattering

International Nuclear Information System (INIS)

Rondon, Oscar A.

2011-01-01

Transverse polarized inelastic scattering extends the power of the electromagnetic interaction as a probe of nucleon dynamics beyond the leading order regime explored with longitudinally polarized DIS. In transverse polarized scattering, the twist-3 g 2 spin structure function contributes at the same order as the longitudinal, twist-2, g 1 , so interactions between quarks and gluons can be studied, opening a window on the mechanisms of confinement. This talk reports the results of Jefferson Lab's Resonances Spin Structure experiment measurement of g 2 and the d 2 twist-3 quark matrix element at a four-momentum transfer of 1.3 GeV 2 .

Manipulating the dipole layer of polar organic molecules on metal surfaces via different charge-transfer channels

Science.gov (United States)

Lin, Meng-Kai; Nakayama, Yasuo; Zhuang, Ying-Jie; Wang, Chin-Yung; Pi, Tun-Wen; Ishii, Hisao; Tang, S.-J.

The key properties of organic films such as energy level alignment (ELA), work functions, and injection barriers are closely linked to this dipole layer. Using angle resolved photoemission spectroscopy (ARPES), we systemically investigate the coverage-dependent work functions and spectra line shapes of occupied molecular orbital states of a polar molecule, chloroaluminium phthalocyanine (ClAlPc), grown on Ag(111) to show that the orientations of the first ClAlPc layer can be manipulated via the molecule deposition rate and post annealing, causing ELA at organic-metal interface to differ for about 0.3 eV between Cl-up and Cl-down configuration. Moreover, by comparing the experimental results with the calculations based on both gas-phase model and realistic model of ClAlPc on Ag(111) , we evidence that the different orientations of ClAlPc dipole layers lead to different charge-transfer channels between ClAlPc and Ag, a key factor that controls the ELA at organic-metal interface.

Spin polarized electron tunneling and magnetoresistance in molecular junctions.

Science.gov (United States)

Szulczewski, Greg

2012-01-01

This chapter reviews tunneling of spin-polarized electrons through molecules positioned between ferromagnetic electrodes, which gives rise to tunneling magnetoresistance. Such measurements yield important insight into the factors governing spin-polarized electron injection into organic semiconductors, thereby offering the possibility to manipulate the quantum-mechanical spin degrees of freedom for charge carriers in optical/electrical devices. In the first section of the chapter a brief description of the Jullière model of spin-dependent electron tunneling is reviewed. Next, a brief description of device fabrication and characterization is presented. The bulk of the review highlights experimental studies on spin-polarized electron tunneling and magnetoresistance in molecular junctions. In addition, some experiments describing spin-polarized scanning tunneling microscopy/spectroscopy on single molecules are mentioned. Finally, some general conclusions and prospectus on the impact of spin-polarized tunneling in molecular junctions are offered.

Investigations of the polarization behavior of quantum cascade lasers by Stokes parameters.

Science.gov (United States)

Janassek, Patrick; Hartmann, Sébastien; Molitor, Andreas; Michel, Florian; Elsäßer, Wolfgang

2016-01-15

We experimentally investigate the full polarization behavior of mid-infrared emitting quantum cascade lasers (QCLs) in terms of measuring the complete Stokes parameters, instead of only projecting them on a linear polarization basis. We demonstrate that besides the pre-dominant linear TM polarization of the emitted light as governed by the selection rules of the intersubband transition, small non-TM contributions, e.g., circularly polarized light, are present reflecting the birefringent behavior of the semiconductor quantum well waveguide. Surprisingly unique is the persistence of these polarization properties well below laser threshold. These investigations give further insight into understanding, manipulating, and exploiting the polarization properties of QCLs, both from a laser point of view and with respect toward applications.

12 CFR 205.10 - Preauthorized transfers.

Science.gov (United States)

2010-01-01

.... The person that obtains the authorization shall provide a copy to the consumer. (c) Consumer's right... shall inform the consumer of the right to receive notice of all varying transfers, but may give the... FUND TRANSFERS (REGULATION E) § 205.10 Preauthorized transfers. (a) Preauthorized transfers to consumer...

Introduction to heat transfer

CERN Document Server

SUNDÉN, B

2012-01-01

Presenting the basic mechanisms for transfer of heat, Introduction to Heat Transfer gives a deeper and more comprehensive view than existing titles on the subject. Derivation and presentation of analytical and empirical methods are provided for calculation of heat transfer rates and temperature fields as well as pressure drop. The book covers thermal conduction, forced and natural laminar and turbulent convective heat transfer, thermal radiation including participating media, condensation, evaporation and heat exchangers.

Elastic proton-deuteron backward scattering: relativistic effects and polarization observables

International Nuclear Information System (INIS)

Kaptari, L.P.; Semikh, S.S.

1997-10-01

The elastic proton-deuteron backward reaction is analyzed within a covariant approach based on the Bethe-Salpeter equation with 000. Lorentz boost and other relativistic effects in the cross section and spin correlation observables, like tensor analyzing power and polarization transfer etc., are investigated in explicit form. Results of numerical calculations for a complete set of polarization observables are presented. (orig.)

Energy transfer in porous anodic alumina/rhodamine 110 nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, University of Tunis Elmanar 2092 Tunis (Tunisia); Harima, N.; Koyama, H. [Hyogo University of Teacher Education, Kato, Hyogo 673-1494 (Japan); Gaponenko, N.V. [Belarusian State University of Informatics and Radioelectronics, P. Browki St. 6, 220013 Minsk (Belarus)

2012-09-15

We have used porous anodic alumina (PAA) films as templates for embedding rhodamine 110 (Rh110) molecules and examined their photoluminescence (PL) properties in detail. The analysis of the polarization memory (PM) of PL strongly suggests that there is a significant energy transfer from PAA to Rh110 molecules. The effect of annealing the PAA layer on the PL properties of the nanocomposite has been studied. The results show that the energy transfer becomes more efficient in annealed PAA. - Highlights: Black-Right-Pointing-Pointer Porous anodic alumina-rhodamine 110 nanocomposites are elaborated. Black-Right-Pointing-Pointer Efficient energy transfer from the host to Rh110 molecules is evidenced from measurements of photoluminescence and degree of polarization memory spectra. Black-Right-Pointing-Pointer Thermal annealing of porous anodic alumina can improve the process of excitation transfer.

Cool Polar Bears: Dabbing on the Texture

Science.gov (United States)

O'Connell, Jean

2011-01-01

In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

Advantages of cross-polarization endoscopic optical coherence tomography in diagnosis of bladder neoplasia

Science.gov (United States)

Gladkova, N. D.; Zagaynova, E. V.; Streltsova, O. S.; Kiseleva, E. B.; Karabut, M. M.; Snopova, L. B.; Yunusova, E. E.; Tararova, E.; Gelikonov, V. M.

2010-02-01

We consider the cross-polarization OCT (CP OCT) that is focused on comparison of images resulting from cross-polarization and co-polarization scattering simultaneously. This technique provides information about microstructural and biochemical alterations in depolarizing tissue components (collagen). We found that mature type I collagen gives a strong signal in orthogonal polarization. CP OCT images of benign inflammatory processes always feature signal in orthogonal polarization, with layers and borders persisting to be well defined. In the presence of precancerous alterations, signal in orthogonal polarization is available in the image but it is irregular, disappearing in some areas. A CP OCT image of bladder cancer in orthogonal polarization either shows no signal at all or a weak signal.

Longitudinal {lambda} and anti {lambda} polarization at the COMPASS experiment

Energy Technology Data Exchange (ETDEWEB)

Kang, Donghee

2007-09-15

At the COMPASS experiment at CERN {lambda} and anti {lambda} particles are produced in deep inelastic scattering (DIS) processes with high statistics. The main focus of the research is the understanding of the spin transfer mechanism from quarks to hadrons through the fragmentation process by utilizing the longitudinal {lambda} and anti {lambda} polarization. The result of the spin transfer provides useful information to test different model predictions which describe spin effects in hyperon production and the quark-antiquark asymmetry of the nucleon and hyperon. The {lambda} and anti {lambda} polarization are determined by measuring the acceptance corrected angular distribution of its decay products. A Monte Carlo simulation is used to correct the acceptance of the COMPASS spectrometer. In this work, preliminary results from data collected in the current fragmentation region during 2002-2004 are presented. A significantly positive average spin transfer of anti {lambda} is found to be equal to C{sub LL}=+0.232{+-}0.039(stat.){+-}0.022(sys.), while the spin transfer of lambda is compatible with zero within the statistical accuracy. The dependences of the spin transfer on various kinematic variables are also presented. (orig.)

Longitudinal Λ and anti Λ polarization at the COMPASS experiment

International Nuclear Information System (INIS)

Kang, Donghee

2007-09-01

At the COMPASS experiment at CERN Λ and anti Λ particles are produced in deep inelastic scattering (DIS) processes with high statistics. The main focus of the research is the understanding of the spin transfer mechanism from quarks to hadrons through the fragmentation process by utilizing the longitudinal Λ and anti Λ polarization. The result of the spin transfer provides useful information to test different model predictions which describe spin effects in hyperon production and the quark-antiquark asymmetry of the nucleon and hyperon. The Λ and anti Λ polarization are determined by measuring the acceptance corrected angular distribution of its decay products. A Monte Carlo simulation is used to correct the acceptance of the COMPASS spectrometer. In this work, preliminary results from data collected in the current fragmentation region during 2002-2004 are presented. A significantly positive average spin transfer of anti Λ is found to be equal to C LL =+0.232±0.039(stat.)±0.022(sys.), while the spin transfer of lambda is compatible with zero within the statistical accuracy. The dependences of the spin transfer on various kinematic variables are also presented. (orig.)

Far-field RF energy transfer and harvesting

NARCIS (Netherlands)

Visser, H.J.; Vullers, R.; Briand, D.; Yeatman, E.; Roundy, S.

2015-01-01

This chapter deals with radio frequency (RF) energy transfer over a distance. After explaining the differences between nonradiative and radiative RF energy transfer, the chapter gives definitions for transfer and harvesting. Nonradiative RF energy transfer is mostly employed in inductive systems,

Specular, diffuse and polarized imagery of an oat canopy

Science.gov (United States)

Vanderbilt, Vern C.; De Venecia, Kurt J.

1988-01-01

Light, polarized by specular reflection, has been found to be an important part of the light scattered by several measured plant canopies. The authors investigate for one canopy the relative importance of specularly reflected sunlight, specularly reflected light from other sources including skylight, and diffusely upwelling light. Polarization images are used to gain increased understanding of the radiation transfer process in a plant canopy. Analysis of the results suggests that properly analyzed polarized remotely sensed data, acquired under specific atmospheric conditions by a specially designed sensor, potentially provide measures of physiological and morphological states of plants in a canopy.

Styring af international transfer pricing

DEFF Research Database (Denmark)

Reuther, Peter; Rossing, Christian Plesner

2011-01-01

Nærværende artikel introducerer international transfer pricing, dels som et skatteretligt fænomen og dels som et værktøj til planlægning og økonomisk styring af koncernforbundne selskaber i en multinational virksomhed (MNV). Med udgangspunkt i en case-analyse af MNV’en gives der et konkret eksempel...... på hvordan transfer pricing håndteres i praksis. Artiklens formål er at give et praktisk eksempel på at transfer pricing handler om at efterleve regler, ikke omgå dem. På baggrund af case-analysen argumenteres der for, at såvel akademikere som praktikere bør tage virksomhedens tilgang til...... international transfer pricing i betragtning, når økonomiske styringssystemer i en MNV skal anvendes til planlægning og opfølgning....

Radiometric calibration of a polarization-sensitive sensor

International Nuclear Information System (INIS)

Ahmad, S.P.; Markham, B.L.

1992-01-01

The radiometric accuracy of a sensor is adversely affected by scene polarization if its optical system is sensitive to polarization. Tests performed on the reflective bands of the NS001 Thematic Mapper simulator, an aircraft multispectral scanner, show that it is very sensitive to the polarization state of the incoming radiations. For 100 percent linearly polarized light, errors in the measured intensity vary from -40 to +40 percent, depending on the scan angle and spectral band. To estimate polarization-induced errors in the intensity measured at aircraft level, the intensity and polarization of the atmospheric radiances were simulated using a realistic earth-atmosphere radiative transfer model. For the polarization of atmospheric radiances in the solar meridian plane over a vegetated target, intensity errors may range from -10 to + 10 percent. The polarization-induced errors are highest in the shortest NS001 spectral band (0.450-0.525 microns) because of large atmospheric polarizations contributed by Rayleigh particles and small diluting effects caused by the small contributions of weakly polarized radiations coming from aerosols and the surface. Depending on the illumination and view angles, the errors in derived surface reflectance due to the radiance errors can be very large. In particular, for large off-nadir view angles in the forward scattered direction when the sun is low, the relative errors in the derived surface reflectance can be as large as 4 to 5 times the relative error in the radiances. Polarization sensitivity errors cannot be neglected for the shorter wavelengths when the surface reflectance contribution to atmospheric radiances is very small. 40 refs

A Measurement of the neutron electric form factor at very large momentum transfer using polaried electrions scattering from a polarized helium-3 target

Energy Technology Data Exchange (ETDEWEB)

Kelleher, Aidan [College of William and Mary, Williamsburg, VA (United States)

2010-02-01

Knowledge of the electric and magnetic elastic form factors of the nucleon is essential for an understanding of nucleon structure. Of the form factors, the electric form factor of the neutron has been measured over the smallest range in Q² and with the lowest precision. Jefferson Lab experiment 02-013 used a novel new polarized ³ He target to nearly double the range of momentum transfer in which the neutron form factor has been studied and to measure it with much higher precision. Polarized electrons were scattered off this target, and both the scattered electron and neutron were detected. Gⁿ _E was measured to be 0.0242 ± 0.0020(stat) ± 0.0061(sys) and 0.0247 ± 0.0029(stat) ± 0.0031(sys) at Q² = 1.7 and 2.5 GeV² , respectively.

High-Frequency Dynamic Nuclear Polarization in the Nuclear Rotating Frame

DEFF Research Database (Denmark)

Farrar, C. T.; Hall, D. A.; Gerfen, G. J.

2000-01-01

A proton dynamic nuclear polarization (DNP) NMR signal enhancement (ϵ) close to thermal equilibrium, ϵ = 0.89, has been obtained at high field (B0 = 5 T, νepr = 139.5 GHz) using 15 mM trityl radical in a 40:60 water/glycerol frozen solution at 11 K. The electron-nuclear polarization transfer...... is performed in the nuclear rotating frame with microwave irradiation during a nuclear spin-lock pulse. The growth of the signal enhancement is governed by the rotating frame nuclear spin–lattice relaxation time (T1ρ), which is four orders of magnitude shorter than the nuclear spin–lattice relaxation time (T1n......). Due to the rapid polarization transfer in the nuclear rotating frame the experiment can be recycled at a rate of 1/T1ρ and is not limited by the much slower lab frame nuclear spin–lattice relaxation rate (1/T1n). The increased repetition rate allowed in the nuclear rotating frame provides an effective...

A 282 GHz Probe for Dynamic Nuclear Polarization

DEFF Research Database (Denmark)

Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy

Introduction In DNP, microwave irradiation of a sample facilitates the transfer of spin polarization from electrons tonuclei. One of the way to improve the DNP enhancement is to transfer microwave power from the mm-wave source tothe sample more effectively. Several methods and techniques to effic......Introduction In DNP, microwave irradiation of a sample facilitates the transfer of spin polarization from electrons tonuclei. One of the way to improve the DNP enhancement is to transfer microwave power from the mm-wave source tothe sample more effectively. Several methods and techniques......: microwave can with RF coil; the rest of the probe consists of a waveguide, sample tube and coaxial transmission line. The probe is designed to study cylindrical samples with diameter - 9 mm, and height – 2-20 mm. An RF coil which is housed in cylindrical Macor coil form (dielectric with ε=5.64 and tangent δ...... is 0.0025) surrounds the sample. The RF coil has a saddle form and was madeout of two current loops run on opposite sides of a cylinder (in parallel). Material of the coil is copper wire with diameterequal to 0.7 mm. Coil dimensions are: diameter - 13 mm; height - 22.0 mm. The self resonant frequency...

Polarization of stable and radioactive noble gas nuclei by spin exchange with laser pumped alkali atoms

International Nuclear Information System (INIS)

Calaprice, F.; Happer, W.; Schreiber, D.

1984-01-01

The nuclei of noble gases can be strongly polarized by spin exchange with sufficiently dense optically pumped alkali vapors. Only a small fraction of the spin angular momentum of the alkali atoms is transferred to the nuclear spin of the noble gas. Most of the spin angular momentum is lost to translational angular momentum of the alkali and noble gas atoms about each other. For heavy noble gases most of the angular momentum transfer occurs in alkali-noble-gas van der Waals molecules. The transfer efficiency depends on the formation and breakup rates of the van der Waals molecules in the ambient gas. Experimental methods to measure the spin transfer efficiencies have been developed. Nuclei of radioactive noble gases have been polarized by these methods, and the polarization has been detected by observing the anisotropy of the radioactive decay products. Very precise measurements of the magnetic moments of the radioactive nuclei have been made. 12 references, 9 figures

Proton polarimeters for spin transfer experiments

International Nuclear Information System (INIS)

McNaughton, M.W.

1985-01-01

The design and use of proton polarimeters for spin transfer (Wolfenstein parameter) measurements is discussed. Polarimeters are compared with polarized targets for spin dependent experiments. 32 refs., 4 figs

Do cephalopods communicate using polarized light reflections from their skin?

Science.gov (United States)

Mäthger, Lydia M; Shashar, Nadav; Hanlon, Roger T

2009-07-01

Cephalopods (squid, cuttlefish and octopus) are probably best known for their ability to change color and pattern for camouflage and communication. This is made possible by their complex skin, which contains pigmented chromatophore organs and structural light reflectors (iridophores and leucophores). Iridophores create colorful and linearly polarized reflective patterns. Equally interesting, the photoreceptors of cephalopod eyes are arranged in a way to give these animals the ability to detect the linear polarization of incoming light. The capacity to detect polarized light may have a variety of functions, such as prey detection, navigation, orientation and contrast enhancement. Because the skin of cephalopods can produce polarized reflective patterns, it has been postulated that cephalopods could communicate intraspecifically through this visual system. The term 'hidden' or 'private' communication channel has been given to this concept because many cephalopod predators may not be able to see their polarized reflective patterns. We review the evidence for polarization vision as well as polarization signaling in some cephalopod species and provide examples that tend to support the notion--currently unproven--that some cephalopods communicate using polarized light signals.

APC: A new code for Atmospheric Polarization Computations

International Nuclear Information System (INIS)

Korkin, Sergey V.; Lyapustin, Alexei I.; Rozanov, Vladimir V.

2013-01-01

A new polarized radiative transfer code Atmospheric Polarization Computations (APC) is described. The code is based on separation of the diffuse light field into anisotropic and smooth (regular) parts. The anisotropic part is computed analytically. The smooth regular part is computed numerically using the discrete ordinates method. Vertical stratification of the atmosphere, common types of bidirectional surface reflection and scattering by spherical particles or spheroids are included. A particular consideration is given to computation of the bidirectional polarization distribution function (BPDF) of the waved ocean surface. -- Highlights: •A new code, APC, has been developed. •The code was validated against well-known codes. •The BPDF for an arbitrary Mueller matrix is computed

Free energy functionals for polarization fluctuations: Pekar factor revisited.

Science.gov (United States)

Dinpajooh, Mohammadhasan; Newton, Marshall D; Matyushov, Dmitry V

2017-02-14

The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. Within dielectric continuum models, this separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom. The main qualitative prediction of Pekar's perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parameter accounting for the solvent effect on electron transfer. Here, we study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from the simulations is numerically close to the Pekar factor. However, we derive a new functionality involving the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found in the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).

Free energy functionals for polarization fluctuations: Pekar factor revisited

International Nuclear Information System (INIS)

Dinpajooh, Mohammadhasan; Newton, Marshall D.; Matyushov, Dmitry V.

2017-01-01

The separation of slow nuclear and fast electronic polarization in problems related to electron mobility in polarizable media was considered by Pekar 70 years ago. This separation leads to the Pekar factor in the free energy of solvation by the nuclear degrees of freedom, within dielectric continuum models. The main qualitative prediction of Pekar’s perspective is a significant, by about a factor of two, drop of the nuclear solvation free energy compared to the total (electronic plus nuclear) free energy of solvation. The Pekar factor enters the solvent reorganization energy of electron transfer reactions and is a significant mechanistic parameter accounting for the solvent effect on electron transfer. We study the separation of the fast and slow polarization modes in polar molecular liquids (polarizable dipolar liquids and polarizable water force fields) without relying on the continuum approximation. We derive the nonlocal free energy functional and use atomistic numerical simulations to obtain nonlocal, reciprocal space electronic and nuclear susceptibilities. A consistent transition to the continuum limit is introduced by extrapolating the results of finite-size numerical simulation to zero wavevector. The continuum nuclear susceptibility extracted from the simulations is numerically close to the Pekar factor. But, we derive a new functionality involving the static and high-frequency dielectric constants. The main distinction of our approach from the traditional theories is found in the solvation free energy due to the nuclear polarization: the anticipated significant drop of its magnitude with increasing liquid polarizability does not occur. The reorganization energy of electron transfer is either nearly constant with increasing the solvent polarizability and the corresponding high-frequency dielectric constant (polarizable dipolar liquids) or actually noticeably increases (polarizable force fields of water).

Magnetic systems for wide-aperture neutron polarizers and analyzers

Energy Technology Data Exchange (ETDEWEB)

Gilev, A.G. [Neutron Research Department, Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Roscha, Gatchina, St. Petersburg 188300 (Russian Federation); Pleshanov, N.K., E-mail: pnk@pnpi.spb.ru [Neutron Research Department, Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Roscha, Gatchina, St. Petersburg 188300 (Russian Federation); Bazarov, B.A.; Bulkin, A.P.; Schebetov, A.F. [Neutron Research Department, Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Roscha, Gatchina, St. Petersburg 188300 (Russian Federation); Syromyatnikov, V.G. [Neutron Research Department, Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Roscha, Gatchina, St. Petersburg 188300 (Russian Federation); Physical Department, St. Petersburg State University, Ulyanovskaya, 1, Petrodvorets, St. Petersburg 198504 (Russian Federation); Tarnavich, V.V.; Ulyanov, V.A. [Neutron Research Department, Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Roscha, Gatchina, St. Petersburg 188300 (Russian Federation)

2016-10-11

Requirements on the field uniformity in neutron polarizers are analyzed in view of the fact that neutron polarizing coatings have been improved during the past decade. The design of magnetic systems that meet new requirements is optimized by numerical simulations. Magnetic systems for wide-aperture multichannel polarizers and analyzers are represented, including (a) the polarizer to be built at channel 4-4′ of the reactor PIK (Gatchina, Russia) for high-flux experiments with a 100×150 mm{sup 2} beam of polarized cold neutrons; (b) the fan analyzer covering a 150×100 mm{sup 2} window of the detector at the Magnetism Reflectometer (SNS, ORNL, USA); (c) the polarizer and (d) the fan analyzer covering a 220×110 mm{sup 2} window of the detector at the reflectometer NERO, which is transferred to PNPI (Russia) from HZG (Germany). Deviations of the field from the vertical did not exceed 2°. The polarizing efficiency of the analyzer at the Magnetism Reflectometer reached 99%, a record level for wide-aperture supermirror analyzers.

To give or not to give, that's the question: How methodology is destiny in Dutch giving data

NARCIS (Netherlands)

Bekkers, R.H.F.P.; Wiepking, P.

2006-01-01

In research on giving, methodology is destiny. The volume of donations estimated from sample surveys strongly depends on the length of the questionnaire used to measure giving. By comparing two giving surveys from the Netherlands, the authors show that a short questionnaire on giving not only

Efficient ionizer for polarized H/sup -/ formation

Energy Technology Data Exchange (ETDEWEB)

Alessi, J.G.

1985-01-01

An ionizer is under development for a polarized H/sup -/ source based on the resonant charge exchange reaction polarized H/sup 0/ + D/sup -/ ..-->.. polarized H/sup -/ + D/sup 0/. The polarized H/sup 0/ beam passes through the center of a magnetron surface-plasma source having an annular geometry, where it crosses a high current (approx.0.5 A), 200 eV D/sup -/ beam. Calculations predict an H/sup 0/ ..-->.. H/sup -/ ionization efficiency of approx.7%, more than an order of magnitude higher than that obtained on present ground state atomic beam sources. In initial experiments using an unpolarized H/sup 0/ beam, H/sup -/ currents in excess of 100 ..mu..A have been measured. While the ionization efficiency is now only about the same as other methods (Cs beam, for example), the results are encouraging since it appears that by injecting positive ions to improve the space-charge neutralization, and by improving the extraction optics, considerable gains in intensity will be made. We will then use this ionizer with a polarized H/sup 0/ beam, and measure the polarization of the resulting H/sup -/ beam. If no depolarization is observed this ionizer will be combined with an atomic beam, cooled to 5 to 6 K, to give a polarized H/sup -/ beam expected to be in the milliampere range for use in the AGS.

Polarization dynamics in nonlinear anisotropic fibers

International Nuclear Information System (INIS)

Komarov, Andrey; Komarov, Konstantin; Meshcheriakov, Dmitry; Amrani, Foued; Sanchez, Francois

2010-01-01

We give an extensive study of polarization dynamics in anisotropic fibers exhibiting a third-order index nonlinearity. The study is performed in the framework of the Stokes parameters with the help of the Poincare sphere. Stationary states are determined, and their stability is investigated. The number of fixed points and their stability depend on the respective magnitude of the linear and nonlinear birefringence. A conservation relation analogous to the energy conservation in mechanics allows evidencing a close analogy between the movement of the polarization in the Poincare sphere and the motion of a particle in a potential well. Two distinct potentials are found, leading to the existence of two families of solutions, according to the sign of the total energy of the equivalent mechanical system. The mechanical analogy allows us to fully characterize the solutions and also to determine analytically the associated beat lengths. General analytical solutions are given for the two families in terms of Jacobi's functions. The intensity-dependent transmission of a fiber placed between two crossed polarizers is calculated. Optimal conditions for efficient nonlinear switching compatible with mode-locking applications are determined. The general case of a nonlinear fiber ring with an intracavity polarizer placed between two polarization controllers is also considered.

Polarization Switching and Light-Enhanced Piezoelectricity in Lead Halide Perovskites.

Science.gov (United States)

Coll, Mariona; Gomez, Andrés; Mas-Marza, Elena; Almora, Osbel; Garcia-Belmonte, Germà; Campoy-Quiles, Mariano; Bisquert, Juan

2015-04-16

We investigate the ferroelectric properties of photovoltaic methylammonium lead halide CH3NH3PbI3 perovskite using piezoelectric force microscopy (PFM) and macroscopic polarization methods. The electric polarization is clearly observed by amplitude and phase hysteresis loops. However, the polarization loop decreases as the frequency is lowered, persisting for a short time only, in the one second regime, indicating that CH3NH3PbI3 does not exhibit permanent polarization at room temperature. This result is confirmed by macroscopic polarization measurement based on a standard capacitive method. We have observed a strong increase of piezoelectric response under illumination, consistent with the previously reported giant photoinduced dielectric constant at low frequencies. We speculate that an intrinsic charge transfer photoinduced dipole in the perovskite cage may lie at the origin of this effect.

New course: "Introduction to knowledge transfer tools"

CERN Multimedia

2014-01-01

The Knowledge Transfer group is now offering a half-day course that will give an introduction to intellectual property, contracts for knowledge transfer, and projects involving industry and other external partners.   The purpose of the course is to give the essential information about how one can secure ownership of inventions and to provide information on legal and contractual considerations when transferring knowledge and technology or when doing collaborative R&D. The course will also highlight some common pitfalls that should be avoided to increase the chances of successfully transferring knowledge and technology. In addition, the course will involve examples of real projects and challenges. The first session will take place the 19 May 2014. To enroll, please follow this link: “Introduction to knowledge transfer tools”.

Diffusion weighted imaging with circularly polarized oscillating gradients

DEFF Research Database (Denmark)

Lundell, Henrik; Sønderby, Casper Kaae; Dyrby, Tim B

2015-01-01

presented. One major hurdle in practical implementation is the low effective diffusion weighting provided at high frequency with limited gradient strength. THEORY: As a solution to the low diffusion weighting of OGSE, circularly polarized OGSE (CP-OGSE) is introduced. CP-OGSE gives a twofold increase...

Coherent pulse and environmental characteristics of the intramolecular proton-transfer lasers based on 3-hydroxyflavone and fisetin

Science.gov (United States)

Parthenopoulos, Dimitri A.; Kasha, Michael

1988-04-01

Coherent stimulated emission and laser beams of good quality are reported for 3-hydroxyfiavone (3-HF) and a polyhydroxyfiavone, risetin, acting as intramolecular proton-transfer lasers. The laser beam quality of these materials is comparable to that observed for rhodamine-6G. Studies of amplified spontaneous emission of 3-hydroxyflavone in highly polar solvents are also reported. The very large changes in dipole moment upon electronic excitation of 3-HF expected according to ZINDO semiempirical molecular orbital calculations fail to give rise to spectral shifts in the high dielectric constant solvents. The results are interpreted as a masking spectral effect caused by specific hydrogen bonding by the solvent.

Spin polarized 3He: a ''new'' quantum fluid

International Nuclear Information System (INIS)

Lhuillier, C.; Laloe, F.

1979-01-01

The physical properties of a 3 He fluid are studied, in which all nuclear spins are parallel to each other (fully polarized 3 He). At low temperatures, significant differences can exist between this polarized fluid and normal 3 He. The origin of these differences is purely quantum mechanical and arises from the Pauli exclusion principle. At low densities, only the transport properties of the gas are modified. At higher densities. The equilibrium properties (virial coefficients) are also changed by the nuclear polarization. Changes of the liquid-vapour or liquid-solid equilibrium pressures, as well as modifications of the 3 He- 4 He mixture phase diagram are predicted. This article gives a preliminary theoretical study of these new effects. Experimental prospects are briefly discussed [fr

Spin-polarization reversal at the interface between benzene and Fe(100)

KAUST Repository

Goumri-Said, Souraya

2013-01-03

The spin-polarization at the interface between Fe(100) and a benzene is investigated theoretically using density functional theory for two positions of the organic molecule: planar and perpendicular with respect to the substrate. The electronic and magnetic properties as well as the spin-polarization close to the Fermi level strongly depend on the benzene position on the iron surface. An inversion of the spin-polarization is induced by p-d hybridization and charge transfer from the iron to the carbon sites in both configurations.

Spin-polarization reversal at the interface between benzene and Fe(100)

KAUST Repository

Goumri-Said, Souraya; Benali Kanoun, Mohammed; Manchon, Aurelien; Schwingenschlö gl, Udo

2013-01-01

The spin-polarization at the interface between Fe(100) and a benzene is investigated theoretically using density functional theory for two positions of the organic molecule: planar and perpendicular with respect to the substrate. The electronic and magnetic properties as well as the spin-polarization close to the Fermi level strongly depend on the benzene position on the iron surface. An inversion of the spin-polarization is induced by p-d hybridization and charge transfer from the iron to the carbon sites in both configurations.

Exploiting level anti-crossings for efficient and selective transfer of hyperpolarization in coupled nuclear spin systems

NARCIS (Netherlands)

Pravdivtsev, A.N.; Yurkovskaya, A.V.; Kaptein, R.; Miesel, K.; Vieth, H.-M.; Ivanov, K.L.

2013-01-01

Spin hyperpolarization can be coherently transferred to other nuclei in field-cycling NMR experiments. At low magnetic fields spin polarization is redistributed in a strongly coupled network of spins. Polarization transfer is most efficient at fields where level anti-crossings (LACs) occur for the

Rotational inertia of continents: A proposed link between polar wandering and plate tectonics

Science.gov (United States)

Kane, M.F.

1972-01-01

A mechanism is proposed whereby displacement between continents and the earth's pole of rotation (polar wandering) gives rise to latitudinal transport of continental plates (continental drift) because of their relatively greater rotational inertia. When extended to short-term polar wobble, the hypothesis predicts an energy change nearly equivalent to the seismic energy rate.

Probing CPT violation with CMB polarization measurements

Energy Technology Data Exchange (ETDEWEB)

Xia Junqing, E-mail: xia@sissa.i [Scuola Internazionale Superiore di Studi Avanzati, Via Beirut 2-4, I-34014 Trieste (Italy); Li Hong; Zhang Xinmin [Institute of High Energy Physics, Chinese Academy of Science, P.O. Box 918-4, Beijing 100049 (China); Theoretical Physics Center for Science Facilities (TPCSF), Chinese Academy of Science (China)

2010-04-12

The electrodynamics modified by the Chern-Simons term L{sub cs}approxp{sub m}uA{sub n}uF-tilde{sup m}u{sup n}u with a non-vanishing p{sub m}u violates the Charge-Parity-Time Reversal symmetry (CPT) and rotates the linear polarizations of the propagating Cosmic Microwave Background (CMB) photons. In this Letter we measure the rotation angle DELTAalpha by performing a global analysis on the current CMB polarization measurements from the five-year Wilkinson Microwave Anisotropy Probe (WMAP5), BOOMERanG 2003 (B03), BICEP and QUaD using a Markov Chain Monte Carlo method. Neglecting the systematic errors of these experiments, we find that the results from WMAP5, B03 and BICEP all are consistent and their combination gives DELTAalpha=-2.62+-0.87deg (68% C.L.), indicating a 3sigma detection of the CPT violation. The QUaD data alone gives DELTAalpha=0.59+-0.42deg (68% C.L.) which has an opposite sign for the central value and smaller error bar compared to that obtained from WMAP5, B03 and BICEP. When combining all the polarization data together, we find DELTAalpha=0.09+-0.36deg (68% C.L.) which significantly improves the previous constraint on DELTAalpha and test the validity of the fundamental CPT symmetry at a higher level.

Nuclear spin polarization of targets

International Nuclear Information System (INIS)

Happer, W.

1990-01-01

Lasers can be used to produce milligrams to grams of noble gas nuclei with spin polarizations in excess of 50%. These quantities are sufficient to be very useful targets in nuclear physics experiments. Alkali-metal atoms are used to capture the angular momentum of circularly polarized laser photons, and the alkali-metal atoms transfer their angular momentum to noble gas atoms in binary or three-body collisions. Non-radiative collisions between the excited alkali atoms and molecular quenching gases are essential to avoid radiation trapping. The spin exchange can involve gas-phase van der Waals molecules, consisting of a noble gas atom and an alkali metal atom. Surface chemistry is also of great importance in determining the wall-induced relaxation rates of the noble gases

From Dark to Light to Fluorescence Resonance Energy Transfer (FRET): Polarity-Sensitive Aggregation-Induced Emission (AIE)-Active Tetraphenylethene-Fused BODIPY Dyes with a Very Large Pseudo-Stokes Shift.

Science.gov (United States)

Şen, Esra; Meral, Kadem; Atılgan, Serdar

2016-01-11

The work presented herein is devoted to the fabrication of large Stokes shift dyes in both organic and aqueous media by combining dark resonance energy transfer (DRET) and fluorescence resonance energy transfer (FRET) in one donor-acceptor system. In this respect, a series of donor-acceptor architectures of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes substituted by one, two, or three tetraphenylethene (TPE) luminogens were designed and synthesised. The photophysical properties of these three chromophore systems were studied to provide insight into the nature of donor-acceptor interactions in both THF and aqueous media. Because the generation of emissive TPE donor(s) is strongly polarity dependent, due to its aggregation-induced emission (AIE) feature, one might expect the formation of appreciable fluorescence emission intensity with a very large pseudo-Stokes shift in aqueous media when considering FRET process. Interestingly, similar results were also recorded in THF for the chromophore systems, although the TPE fragment(s) of the dyes are non-emissive. The explanation for this photophysical behaviour lies in the DRET. This is the first report on combining two energy-transfer processes, namely, FRET and DRET, in one polarity-sensitive donor-acceptor pair system. The accuracy of the dark-emissive donor property of the TPE luminogen is also presented for the first time as a new feature for AIE phenomena. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light scattering reviews 8 radiative transfer and light scattering

CERN Document Server

Kokhanovsky, Alexander A

2013-01-01

Light scattering review (vol 8) is aimed at the presentation of recent advances in radiative transfer and light scattering optics. The topics to be covered include: scattering of light by irregularly shaped particles suspended in atmosphere (dust, ice crystals), light scattering by particles much larger as compared the wavelength of incident radiation, atmospheric radiative forcing, astrophysical radiative transfer, radiative transfer and optical imaging in biological media, radiative transfer of polarized light, numerical aspects of radiative transfer.

Study of the proton structure by measurements of polarization transfers in real Compton scattering at J Lab

International Nuclear Information System (INIS)

Fanelli, C.; Salme, G.; Cisbani, E.; Hamilton, D.; Wojtsekhowski, B.

2014-01-01

A preliminary analysis of polarization-transfer data at large scattering angle (70 degrees), obtained in an experiment of real Compton scattering on proton, performed in Hall-C of Jefferson Lab, is presented. It is also discussed the relevance of this kind of experiments for shedding light on the non-perturbative structure of the proton, at low energy, and on the transition from the non-perturbative regime to the perturbative one, that occurs at high energy. Moreover, the possibility to extract Compton form factors and the Generalized Parton Distributions (GPD), one of the most promising theoretical tool to determine the total angular momentum contribution of quarks and gluons to nucleon spin, is emphasized. The preliminary results appear consistent with GPD's based and Regge predictions. This is not sufficient yet to exclude pQCD COZ (Chernyak-Oglobin-Zhitnistsky) model, but it is another preliminary indication that the handbag approach seems to be the dominant mechanism at the energy of the experiment

Screening of spontaneous polarization in lead titanate crystals

International Nuclear Information System (INIS)

Gavrilyachenko, V.G.; Semenchev, A.F.; Fesenko, E.G.

1996-01-01

Results of experimental investigations into electric conductivity of lead titanate crystals with different domain structure including single-domain are reported. The data obtained give grounds to believe that spontaneous titanate polarization is realized by the surface level and charge volumetric of free carriers and ionized impurity

Investigation of PTFE transfer films by infrared emission spectroscopy and phase-locked ellipsometry

Science.gov (United States)

Lauer, James L.; Bunting, Bruce G.; Jones, William R., Jr.

1988-01-01

When a PTFE sheet was rubbed unidirectionally over a smooth surface of stainless steel an essentially monomolecular transfer film was formed. by ellipsometric and emission infrared spectroscopic techniques it was shown that the film was 10 to 15 A thick and birefringent. From the intensity differences of infrared bands obtained with a polarizer passing radiation polarized in mutually perpendicular planes, it was possible to deduce transfer film orientation with the direction of rubbing. After standing in air for several weeks the transfer films apparently increased in thickness by as much as threefold. At the same time both the index of refraction and the absorption index decreased. Examination of the surfaces by optical and electron microscopies showed that the films had become porous and flaky. These observations were consistent with previous tribological measurements. The coefficients of friction decreased with the formation of the transfer film but increased again as the film developed breaks. The applicability of the ellipsometric and polarized infrared emission techniques to the identification of monomolecular tribological transfer films of polymers such as PTFE has been demonstrated.

The polarized proton and deuteron beam at the Bonn isochronous cyclotron

Energy Technology Data Exchange (ETDEWEB)

Bauer, K G; Enders, R; Hammon, W; Krause, K D; Lesemann, D; Scholzen, A [Bonn Univ. (F.R. Germany). Inst. fuer Angewandte Physik; Euler, K; Schueller, B [Bonn Univ. (F.R. Germany). Inst. fuer Strahlen- und Kernphysik

1976-02-15

The present state of the polarized proton and deuteron source at the Bonn cyclotron is described. The source, which is of the atomic beam type, gives typical ion beam intensities of 2 ..mu..A for protons and 3 ..mu..A for deuterons. The overall transmission from the source to the first stopper after extraction from the cyclotron is 3%. Target currents with an energy resolution E/..delta..E=500 are 20 nA for deuterons and 10 nA for protons. For the proton beam, a polarization P=-0.71 was measured. For the deuteron beam, a pure vector polarization Psub(z)=-0.47 or various mixtures of vector and tensor polarization are obtained.

Optical field-strength polarization of two-mode single-photon states

Energy Technology Data Exchange (ETDEWEB)

Linares, J; Nistal, M C; Barral, D; Moreno, V, E-mail: suso.linares.beiras@usc.e [Optics Area, Department of Applied Physics, Faculty of Physics and School of Optics and Optometry, University of Santiago de Compostela, Campus Universitario Sur s/n, 15782-Santiago de Compostela, Galicia (Spain)

2010-09-15

We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

Optical field-strength polarization of two-mode single-photon states

International Nuclear Information System (INIS)

Linares, J; Nistal, M C; Barral, D; Moreno, V

2010-01-01

We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

Polarized excitons and optical activity in single-wall carbon nanotubes

Science.gov (United States)

Chang, Yao-Wen; Jin, Bih-Yaw

2018-05-01

The polarized excitons and optical activity of single-wall carbon nanotubes (SWNTs) are studied theoretically by π -electron Hamiltonian and helical-rotational symmetry. By taking advantage of the symmetrization, the single-particle energy and properties of a SWNT are characterized with the corresponding helical band structure. The dipole-moment matrix elements, magnetic-moment matrix elements, and the selection rules can also be derived. Based on different selection rules, the optical transitions can be assigned as the parallel-polarized, left-handed circularly-polarized, and right-handed circularly-polarized transitions, where the combination of the last two gives the cross-polarized transition. The absorption and circular dichroism (CD) spectra are simulated by exciton calculation. The calculated results are well comparable with the reported measurements. Built on the foundation, magnetic-field effects on the polarized excitons and optical activity of SWNTs are studied. Dark-bright exciton splitting and interband Faraday effect in the CD spectrum of SWNTs under an axial magnetic field are predicted. The Faraday rotation dispersion can be analyzed according to the selection rules of circular polarizations and the helical band structure.

A new interpretation of Serkowski's polarization law

Science.gov (United States)

Papoular, R.

2018-06-01

The basic tenets of the alternative interpretation to be presented here are that the spectral profiles of the star light polarization peaks observed in the visible and near IR are a result of the optical properties of silicate grains in the same spectral range, not of the grain size, provided it remains within the range of Rayleigh's approximation. The silicate properties are those obtained experimentally by Scott and Duley (1996) for the non-iron bearing amorphous forsterite and enstatite. The whole range of observed Serkowski polarization profiles can be simulated with mixtures made of forsterite plus an increasing fraction (0 to 0.5) of enstatite as the spectral peak shifts from 0.8 to 0.3 μm. Fits to individual observed polarization spectra are also demonstrated. The optical extinction of silicates in the vis/IR (the "transparency range") can be understood by analogy with the thoroughly studied amorphous hydrogenated carbons and amorphous silica. It is due to structural disorder (dangling bonds and coordination defects) and impurities, which give rise to electronic states in the forbidden gap of semi-conductors. Because they are partially localized, their extinction power is dramatically reduced and has been ignored or simply described by a low, flat plateau. As their number density depends on the environment, one expects variations in the ratio of optical extinction coefficients in the visible and mid-IR. It is also argued that the measured steep rise of extinction beyond 3 μm-1 into the UV is due to atomic transitions, and so cannot give rise to coherent molecular polarization, but only localized extinction.

Polarization Properties of Laser Solitons

Directory of Open Access Journals (Sweden)

Pedro Rodriguez

2017-04-01

Full Text Available The objective of this paper is to summarize the results obtained for the state of polarization in the emission of a vertical-cavity surface-emitting laser with frequency-selective feedback added. We start our research with the single soliton; this situation presents two perpendicular main orientations, connected by a hysteresis loop. In addition, we also find the formation of a ring-shaped intensity distribution, the vortex state, that shows two homogeneous states of polarization with very close values to those found in the soliton. For both cases above, the study shows the spatially resolved value of the orientation angle. It is important to also remark the appearance of a non-negligible amount of circular light that gives vectorial character to all the different emissions investigated.

COMPASS polarized target for Drell-Yan

CERN Document Server

Pešek, M

2014-01-01

In the COMPASS Drell–Yan experiment the pion beam with momen tum of 190 GeV/ c and in- tensity up to 10 8 pions/s will interact with transversely polarized proton t arget producing muon pair via Drell–Yan process. The solid-state NH 3 will be polarized by dynamic nuclear polar- ization. Maximum polarization reached during data taking i s expected to be up to 90%. The non-interacting beam and other particles produced inside t he target will be stopped in the hadron absorber after the target. Two target cells, sepparated by a 20 cm gap in between, each 55 cm long and 4 cm in diameter give the target material volume about 691 cm 3 . The target platform needs to be moved by 2.3 m in upstream dire ction from the position used in previous experiments in order to accomodate the absorber. D uring the beam time higher radiation is expected in the area of the control room. Thus a new target r emote control system is needed. The target magnet is undergoing a substantial upgrade. Drell–Yan data taking is expected t...

To Give or Not to Give, That Is the Question : How Methodology Is Destiny in Dutch Giving Data

NARCIS (Netherlands)

Bekkers, René; Wiepking, Pamala

2006-01-01

In research on giving, methodology is destiny. The volume of donations estimated from sample surveys strongly depends on the length of the questionnaire used to measure giving. By comparing two giving surveys from the Netherlands, the authors show that a short questionnaire on giving not only

COST meeting - Polarization and AGN II - Abstracts and slides

International Nuclear Information System (INIS)

Kishimoto, M.; Rouan, D.; Tadhunter, C.; Lopez Rodriguez, E.; Braibant, L.; Pasetto, A.; Matt, G.; Afanasiev, V.; Lira, P.; Hutsemekers, D.; Sluse, D.; Marin, F.; Tamborra, F.; Yankova, K.; Laing, R.; Lico, R.; Agudo, I.; Hovatta, T.; Jermak, H.; Chen, X.; Myserlis, I.; Cellone, S.A.; Chidiac, C.; Chakraborty, N.; Bozhilov, V.

2016-01-01

This meeting is the 2. COST workshop on Polarization and Active Galactic Nuclei (AGN). Accreting supermassive black holes in active galactic nuclei are the most powerful, long-lasting sources in the universe. Emitting over ten orders of magnitude in photon energy or more, the radiation of AGN encodes information about a multitude of astrophysical processes: accretion, thermal and non-thermal radiative transfer, acceleration of outflows and jets, shock physics, special and general relativity. Observationally, AGN appear as numerous types and polarization studies have played a key role in establishing the idea of a unifying AGN geometry. The topics covered at the meeting include the following: 1) Polarimetry of AGN from the radio to gamma-rays; 2) Tools for modeling and data analysis of AGN polarization; 3) Polarization due to magnetic fields and dust in AGN; 4) Polarization of AGN inflows, outflows and jets; 5) Spectropolarimetry and polarization variability of AGN; and 6) From Sgr A* to the most luminous quasars: what can polarimetry do for AGN (super-)unification? This document is made up of the abstracts and slides of the presentations

Measurement of spin-transfer observables in pp to $\\Lambda \\Lambda$ at 1.637 GeV/c

CERN Document Server

Bassalleck, B; Bradtke, C; Bröders, R; Bunker, B; Dennert, H; Dutz, H; Eilerts, S W; Eyrich, W; Fields, D; Fischer, H; Franklin, G; Franz, J; Gehring, R; Geyer, R; Görtz, S; Harmsen, J; Hauffe, J; Heinsius, F H; Hertzog, D W; Johansson, T; Jones, T; Khaustov, P; Kilian, K; Kingsberry, P; Kriegler, E; Lowe, J; Meier, A; Metzger, A E; Meyer, C A; Meyer, Werner T; Moosburger, M; Oelert, W; Paschke, K D; Plückthun, M; Pomp, S; Quinn, B; Radtke, E; Reicherz, G; Röhrich, K; Sachs, K; Schmitt, H; Schoch, B; Sefzick, T; Stinzing, F; Stotzer, R W; Tayloe, R; Wirth, S

2002-01-01

Spin-transfer observables for pp to Lambda Lambda have been measured using a transversely polarized frozen-spin target and a beam momentum of 1.637 GeV/c. Current models of the reaction near threshold are in good agreement with existing measurements performed with unpolarized particles in the initial state but produce conflicting predictions for the spin-transfer observables D/sub nn/ and K/sub nn/ (the normal-to-normal depolarization and polarization transfer), which are measurable only with polarized target or beam. Measurements of D/sub nn/ and K/sub nn/ presented here are found to be in disagreement with predictions from these models. (21 refs).

Analysis of polarization in hydrogen bonded complexes: An asymptotic projection approach

Science.gov (United States)

Drici, Nedjoua

2018-03-01

The asymptotic projection technique is used to investigate the polarization effect that arises from the interaction between the relaxed, and frozen monomeric charge densities of a set of neutral and charged hydrogen bonded complexes. The AP technique based on the resolution of the original Kohn-Sham equations can give an acceptable qualitative description of the polarization effect in neutral complexes. The significant overlap of the electron densities, in charged and π-conjugated complexes, impose further development of a new functional, describing the coupling between constrained and non-constrained electron densities within the AP technique to provide an accurate representation of the polarization effect.

Polarization Study for NLC Positron Source Using EGS4

Energy Technology Data Exchange (ETDEWEB)

Liu, James C

2000-09-20

SLAC is exploring a polarized positron source to study new physics for the NLC project. The positron source envisioned in this paper consists of a polarized electron source, a 50-MeV electron accelerator, a thin target less-than-or-equal-to 0.2 radiation length for positron production, and a capture system for high-energy, small angular divergence positrons. The EGS4 code was used to study the yield, energy spectra, emission-angle distribution, and the mean polarization of the positrons emanating from W-Re and Ti targets hit by longitudinally polarized electron and photon beams. To account for polarization within the EGS4 code a method devised by Flottmann was used, which takes into account polarization transfer for pair production, bremsstrahlung, and Compton interactions. A mean polarization of 0.85 for positrons with energies greater than 25 MeV was obtained. Most of the high-energy positrons were emitted within a forward angle of 20 degrees. The yield of positrons above 25 MeV per incident photon was 0.034, which was about 70 times higher than that obtained with an electron beam.

Proton polarizing system with Ar-ion laser for p-vector-RI scattering experiments

International Nuclear Information System (INIS)

Wakui, T.; Hatano, M.; Sakai, H.; Uesaka, T.; Tamii, A.

2005-01-01

A proton polarizing system for use in scattering experiments with radioactive isotope beams is described. Protons in a naphthalene crystal doped with pentacene are polarized in a magnetic field of 0.3T at 100K by transferring a large population difference among the photo-excited triplet states of pentacene to the hydrogen nuclei. An Ar-ion laser, which demands minimal maintenance during scattering experiments, is employed to excite the pentacene molecules. A proton polarization of 37% is obtained

Quantum theory of nonadiabatic heavy-particle transfer processes in polar media

International Nuclear Information System (INIS)

Kuznetsov, A.M.

1986-01-01

For the probability of nonadiabatic transfer of heavy particles, a calculating procedure is proposed which in the case of certain processes allows the interaction between motion of the particle undergoing transfer and motion along other degrees of freedom to be exactly accounted for. In the case of symmetric systems, explicit expressions are obtained for the free energy of activation of the transition and for the tunneling factor which allow for nonadiabaticity of motion of the particle undergoing transfer, both in the region beneath the barrier and in the region that is classically accessible

Plasmonic vortex generator without polarization dependence

Science.gov (United States)

Wang, Han; Liu, Lixia; Liu, Chunxiang; Li, Xing; Wang, Shuyun; Xu, Qing; Teng, Shuyun

2018-03-01

In view of the limitations of vortex generators with polarization dependence at present, we propose a plasmonic vortex generator composed of rectangular holes etched in silver film, in which the optical vortex can be generated under arbitrary linearly polarized light illumination. Two sets of rectangular holes are arranged equidistantly on a circle and rotate in postulate directions. Theoretical analysis provides the design principle for the vortex generator, and numerical simulations give guidance on designating the vortex generator parameters. Experimental measurements verify the performance of the proposed vortex generator. Moreover, two alternative structures for the generation of a plasmonic vortex are also provided in this paper. The resulting perfect vortex, compact structure and flexible illumination conditions will lead to wide applications of this plasmonic vortex generator.

Measurement of K/sub NN/, K/sub SS/, K/sub SL/, and K/sub LL/ in polarized np → polarized pn at 800 MeV in the CEX region

International Nuclear Information System (INIS)

Ransome, R.D.; Hollas, C.L.; Riley, P.J.

1980-01-01

The spin transfer parameters K/sub NN/, K/sub SS/, K/sub SL/, and K/sub LL/ have been measured for np elastic scattering at 800 MeV between 165 0 and 180 0 c.m. The parameters K/sub NN/ and K/sub LL/ are in good agreement with the quasi-free reaction polarized pd → polarized npp at 180 0

Optical characterization and polarization calibration for rigid endoscopes

Science.gov (United States)

Garcia, Missael; Gruev, Viktor

2017-02-01

Polarization measurements give orthogonal information to spectral images making them a great tool in the characterization of environmental parameters in nature. Thus, polarization imagery has proven to be remarkably useful in a vast range of biomedical applications. One such application is the early diagnosis of flat cancerous lesions in murine colorectal tumor models, where polarization data complements NIR fluorescence analysis. Advances in nanotechnology have led to compact and precise bio-inspired imaging sensors capable of accurately co-registering multidimensional spectral and polarization information. As more applications emerge for these imagers, the optics used in these instruments get very complex and can potentially compromise the original polarization state of the incident light. Here we present a complete optical and polarization characterization of three rigid endoscopes of size 1.9mm x 10cm (Karl Storz, Germany), 5mm x 30cm, and 10mm x 33cm (Olympus, Germany), used in colonoscopy for the prevention of colitis-associated cancer. Characterization results show that the telescope optics act as retarders and effectively depolarize the linear component. These incorrect readings can cause false-positives or false-negatives leading to an improper diagnosis. In this paper, we offer a polarization calibration scheme for these endoscopes based on Mueller calculus. By modeling the optical properties from training data as real-valued Mueller matrices, we are able to successfully reconstruct the initial polarization state acquired by the imaging system.

Nonlinear and anisotropic polarization rotation in two-dimensional Dirac materials

Science.gov (United States)

Singh, Ashutosh; Ghosh, Saikat; Agarwal, Amit

2018-05-01

We predict nonlinear optical polarization rotation in two-dimensional massless Dirac systems including graphene and 8-P m m n borophene. When illuminated, a continuous-wave optical field leads to a nonlinear steady state of photoexcited carriers in the medium. The photoexcited population inversion and the interband coherence give rise to a finite transverse optical conductivity σx y(ω ) . This in turn leads to definitive signatures in associated Kerr and Faraday polarization rotation, which are measurable in a realistic experimental scenario.

Quantitative determination of high-Tc superconductivity from the lattice polarization, structure effect and approach to 300 K Tc

International Nuclear Information System (INIS)

Green, B.A.

1997-01-01

The quasiparticle state defined by the low temperature polar mobility is a large, quantized positive energy shift that is identical to the constant pairing energy (pseudogap and 2Λ) in the multi-plane high-T c superconductors, showing the lattice polarization produces the single-particle shift and pairing which then transfer to the superconducting state. The coupling-independence and state transfer follow from the nonlocality and action length of the polarization interaction, and the multiple plane requirement from the location of the polar mode. 2Δ is thereby obtained directly, without scaling, from the strong interaction on the plane. The interaction accordingly produces a dynamic, highly stable state, in contrast to BCS superconductors, and the zero-order state is the quantized energy shift. (orig.)

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy.

Science.gov (United States)

Fidler, Andrew F; Singh, Ved P; Long, Phillip D; Dahlberg, Peter D; Engel, Gregory S

2013-10-21

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fidler, Andrew F.; Singh, Ved P.; Engel, Gregory S. [Department of Chemistry, The Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Long, Phillip D.; Dahlberg, Peter D. [Graduate Program in the Biophysical Sciences, The University of Chicago, Chicago, Illinois 60637 (United States)

2013-10-21

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

International Nuclear Information System (INIS)

Fidler, Andrew F.; Singh, Ved P.; Engel, Gregory S.; Long, Phillip D.; Dahlberg, Peter D.

2013-01-01

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex

System for the chemical professing and evaluation gives the residual thickness the gives detecting for gives appearances LR115 type 2

International Nuclear Information System (INIS)

Carrazana Gonzalez, J.A.; Tomas Zerquera, J.; Prendes Alonso, M.

1998-01-01

In this work the system is described built in the CPHR for the homogeneous chemical processing gives detecting gives nuclear appearances. A new developed method is exposed, based on the application gives the technique optical densitometry, for the precise estimate gives the residual thickness, gives detecting, gives nuclear appearances LR115 type 2 after the process gives chemical engraving

New POLDI - project of reincarnation of a polarized neutron diffractometer at the reactor PIK

Science.gov (United States)

Zobkalo, I.; Gavrilov, S.; Matveev, V.; Fenske, J.

2017-06-01

The project of a considerable modernization of the polarized neutron diffractometer POLDI is discussed. It assumes the adoption of POLDI to a broader range of magnetic investigations such as determination of magnetic structures, detailed investigation of complex magnetic structures, studies of magnetic domains, study of the magnetization density maps, magnetic form-factor particularities, local susceptibility, etc. The flexible construction should permit to use either spherical neutron polarimetry technique or flipping ratio technique. Different types of polarization system were analyzed. Original focusing fan-like bender is proposed as polarizer unit. Our simulations give evidence that for the wavelength range 1.3 - 3 Å and with suitable size, such a device can give much better efficiency than 3He cells, which are often in use. The higher flux at the sample position of a factor of at least 3.3, with lower divergence and good polarization degree from 98% (1.3 Å) to above 94% (3 Å) makes the bender set-up favorable over the layout with a 3He-cell.

Li breakup polarization potential at near barrier energies

International Nuclear Information System (INIS)

Lubian, F. J.; Correa, T.; Gomes, P.R.S.; Paes, B; Figueira, J. M.; Abriola, D.; Fernandez, J. O.; Capurro, O. A.; Marti, G.V.; Martinez, D.; Heimann; Negri, A.; Pacheco, A. J.; Padron, I.

2007-01-01

Inelastic and one neutron transfer cross sections at energies around the Coulomb barrier were used to derive dynamic polarization potential (DPP) for the 7 Li + 27 Al system. The DPP due to breakup, obtained in a simple way, indicates that its real part is repulsive at nearbarrier energies. (Author)

On some methods to produce high-energy polarized electron beams by means of proton synchrotrons

International Nuclear Information System (INIS)

Bessonov, E.G.; Vazdik, Ya.A.

1980-01-01

Some methods of production of high-energy polarized electron beams by means of proton synchrotrons are considered. These methods are based on transfer by protons of a part of their energy to the polarized electrons of a thin target placed inside the working volume of the synchrotron. It is suggested to use as a polarized electron target a magnetized crystalline iron in which proton channeling is realized, polarized atomic beams and the polarized plasma. It is shown that by this method one can produce polarized electron beams with energy approximately 100 GeV, energy spread +- 5 % and intensity approximately 10 7 electron/c, polarization approximately 30% and with intensity approximately 10 4 -10 5 electron/c, polarization approximately 100% [ru

Proton-transfer reactions in ionized gases

International Nuclear Information System (INIS)

Stiller, W.; Schmidt, R.; Schuster, R.

1985-01-01

Ion-molecule reactions play an important role in various radiolytic processes, e.g. gas-pulse radiolysis, environmental research. For a discussion of mechanisms rate coefficients have to be assessed. Here gas-phase rate coefficients of ion-(polar) molecule reactions are calculated using the ideas of interaction potentials, reactive cross-sections and distribution functions of the translational energies of both the reactants (ions I, molecules M). The starting point of our approach, directed especially to gas-phase proton-transfer reactions, is the idea that the rate coefficient k can be calculated as an ion-molecule capture-rate coefficient multiplied by a 'steric factor' representing the probability for proton transfer. Mutual capture of the reaction partners within a possible reaction zone is caused by the physical interaction between an ion and a polar molecule. A model is discussed. Results are presented. (author)

Selective Deflection of Polarized Light Via Coherently Driven Four-Level Atoms in a Double-Λ Configuration

International Nuclear Information System (INIS)

Guo Yu

2010-01-01

We study the interaction of a weak probe field, having two circular polarized components, i.e., σ - and σ + polarization, with an optically dense medium of four-level atoms in a double-Λ configuration, which is mediated by the electromagnetically induced transparency with a polarized control light with spatially inhomogeneous profile. We analyse the deflection of the polarized probe light and we find that we can selectively determine which circular component will be deflected after the polarized probe light enters the atom medium via adjusting the polarization and detuning of the control field. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Molecular electron recollision dynamics in intense circularly polarized laser pulses

Science.gov (United States)

Bandrauk, André D.; Yuan, Kai-Jun

2018-04-01

Extreme UV and x-ray table top light sources based on high-order harmonic generation (HHG) are focused now on circular polarization for the generation of circularly polarized attosecond pulses as new tools for controlling electron dynamics, such as charge transfer and migration and the generation of attosecond quantum electron currents for ultrafast magneto-optics. A fundamental electron dynamical process in HHG is laser induced electron recollision with the parent ion, well established theoretically and experimentally for linear polarization. We discuss molecular electron recollision dynamics in circular polarization by theoretical analysis and numerical simulation. The control of the polarization of HHG with circularly polarized ionizing pulses is examined and it is shown that bichromatic circularly polarized pulses enhance recollision dynamics, rendering HHG more efficient, especially in molecules because of their nonspherical symmetry. The polarization of the harmonics is found to be dependent on the compatibility of the rotational symmetry of the net electric field created by combinations of bichromatic circularly polarized pulses with the dynamical symmetry of molecules. We show how the field and molecule symmetry influences the electron recollision trajectories by a time-frequency analysis of harmonics. The results, in principle, offer new unique controllable tools in the study of attosecond molecular electron dynamics.

Detecting chameleons: The astronomical polarization produced by chameleonlike scalar fields

International Nuclear Information System (INIS)

Burrage, Clare; Davis, Anne-Christine; Shaw, Douglas J.

2009-01-01

We show that a coupling between chameleonlike scalar fields and photons induces linear and circular polarization in the light from astrophysical sources. In this context chameleonlike scalar fields include those of the Olive-Pospelov (OP) model, which describes a varying fine structure constant. We determine the form of this polarization numerically and give analytic expressions in two useful limits. By comparing the predicted signal with current observations we are able to improve the constraints on the chameleon-photon coupling and the coupling in the OP model by over 2 orders of magnitude. It is argued that, if observed, the distinctive form of the chameleon induced circular polarization would represent a smoking gun for the presence of a chameleon. We also report a tentative statistical detection of a chameleonlike scalar field from observations of starlight polarization in our galaxy.

A polarized atomic-beam target for COSY-Juelich

International Nuclear Information System (INIS)

Eversheim, P. D.; Altmeier, M.; Felden, O.; Glende, M.; Walker, M.; Hiemer, A.; Gebel, R.

1998-01-01

An atomic-beam target (ABT) for the EDDA experiment has been built in Bonn and was tested for the very first time at the cooler synchrotron COSY. The ABT differs from the polarized colliding-beams ion source for COSY in the DC-operation of the dissociator and the use of permanent 6-pole magnets. At present the beam optics of the ABT is set-up for maximum density in the interaction zone, but for target-cell operation it can be modified to give maximum intensity. The modular concept of this atomic ground-state target allows to provide all vector- (and tensor) polarizations for protons and deuterons, respectively. Up to now the polarization of the atomic-beam could be verified by the EDDA experiment to be > or approx. 80% with a density in the interaction zone of > or approx. 10 11 atoms/cm 2

Fractal structure of hadrons in processes with polarized protons at SPD NICA (proposal for experiment)

International Nuclear Information System (INIS)

Tokarev, M.V.; Aparin, A.A.; Zborovsky, I.

2014-01-01

The concept of z-scaling previously developed for analysis of inclusive reactions in proton-proton collisions is applied for description of processes with polarized protons at the planned Spin Physics Detector NICA in Dubna. A hypothesis of self-similarity and fractality of the proton spin structure is discussed. The possibilities to extract information on spin-dependent fractal dimensions of hadrons and fragmentation process from asymmetries and coefficients of polarization transfer are justified. The double longitudinal spin asymmetry A LL of π 0 -meson production and the coefficient of the polarization transfer D LL of Λ hyperon production in proton-proton collisions measured at RHIC are analyzed in the framework of z-scaling. The spin-dependent fractal dimensions of proton and fragmentation process with polarized Λ hyperon are estimated. A study of the spin-dependent constituent energy loss as a function of transverse momentum of the inclusive hadron and collision energy is suggested.

Many-body kinetics of dynamic nuclear polarization by the cross effect

Science.gov (United States)

Karabanov, A.; Wiśniewski, D.; Raimondi, F.; Lesanovsky, I.; Köckenberger, W.

2018-03-01

Dynamic nuclear polarization (DNP) is an out-of-equilibrium method for generating nonthermal spin polarization which provides large signal enhancements in modern diagnostic methods based on nuclear magnetic resonance. A particular instance is cross-effect DNP, which involves the interaction of two coupled electrons with the nuclear spin ensemble. Here we develop a theory for this important DNP mechanism and show that the nonequilibrium nuclear polarization buildup is effectively driven by three-body incoherent Markovian dissipative processes involving simultaneous state changes of two electrons and one nucleus. We identify different parameter regimes for effective polarization transfer and discuss under which conditions the polarization dynamics can be simulated by classical kinetic Monte Carlo methods. Our theoretical approach allows simulations of the polarization dynamics on an individual spin level for ensembles consisting of hundreds of nuclear spins. The insight obtained by these simulations can be used to find optimal experimental conditions for cross-effect DNP and to design tailored radical systems that provide optimal DNP efficiency.

Polarization effects in radiative recombination of an electron with a highly charged ion

International Nuclear Information System (INIS)

Klasnikov, A.E.; Shabaev, V.M.; Artemyev, A.N.; Kovtun, A.V.; Stoehlker, T.

2005-01-01

The radiative recombination of an unpolarized electron with a polarized highly charged H-like ion in its ground state is studied. The absolute and relative values of the electron spin-flip contribution to the cross section of the process for various scattering angles and photon polarizations are calculated. It is shown that, in addition to the forward and backward directions, there are some other scattering angles of the emitted photon, where, at a fixed linear photon polarization, the spin-flip transition gives a dominant contribution to the differential cross section

Production and polarization of the Λc+ and the charm of the proton

International Nuclear Information System (INIS)

Anjos, J. dos; Magnin, J.; Simao, F.R.A.; Herrera, G.

1997-02-01

We propose a two component model involving the parton fusion mechanism and recombination of the ud valence diquark with a sea c-quark of the incident proton to describe Λ c + inclusive production in pp collisions. We also study the polarization of the produced Λ c + in the framework of the Thomas Precession Model for polarization. We show that a measurement of the Λ c polarization is a sensitive test of its production mechanism. In particular the intrinsic charm model predicts a positive polarization for the Λ c within the framework of the Thomas Precession Model, while according to the model presented here the Λ c polarization should be negative. The measurement of the Λ c polarization provides a close examination of intrinsic charm Fock states in the proton and give interesting information about the hadroproduction of charm. (author)

High-energy polarized proton beams a modern view

CERN Document Server

Hoffstaetter, Georg Heinz

2006-01-01

This monograph begins with a review of the basic equations of spin motion in particle accelerators. It then reviews how polarized protons can be accelerated to several tens of GeV using as examples the preaccelerators of HERA, a 6.3 km long cyclic accelerator at DESY / Hamburg. Such techniques have already been used at the AGS of BNL / New York, to accelerate polarized protons to 25 GeV. But for acceleration to energies of several hundred GeV as in RHIC, TEVATRON, HERA, LHC, or a VLHC, new problems can occur which can lead to a significantly diminished beam polarization. For these high energies, it is necessary to look in more detail at the spin motion, and for that the invariant spin field has proved to be a useful tool. This is already widely used for the description of high-energy electron beams that become polarized by the emission of spin-flip synchrotron radiation. It is shown that this field gives rise to an adiabatic invariant of spin-orbit motion and that it defines the maximum time average polarizat...

Heat Transfer and Cooling Techniques at Low Temperature

CERN Document Server

Baudouy, B

2014-07-17

The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

Heat Transfer and Cooling Techniques at Low Temperature

Energy Technology Data Exchange (ETDEWEB)

Baudouy, B [Saclay (France)

2014-07-01

The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

An Operator Perturbation Method of Polarized Line Transfer V ...

Indian Academy of Sciences (India)

tribpo

imate Lambda Iteration) method to the resonance scattering in spectral lines formed in the presence of weak magnetic fields. The method is based on an operator perturbation approach, and can efficiently give solutions for oriented vector magnetic fields in the solar atmosphere. Key words. ... 1999 for observational.

Excellent polarization-independent reflector based on guided mode resonance effect

International Nuclear Information System (INIS)

Xu Cheng; Xu Lin-Min; Qiang Ying-Huai; Zhu Ya-Bo; Liu Jiong-Tian; Ma Jian-Yong

2011-01-01

A broad band polarization-independent reflector working in the telecommunication C+L band is proposed using the guided mode resonance effect of a periodic surface relief element deposited by a layer of silicon medium. It is shown that this structure can provide high reflection (R > 99.5%) and wide angular bandwidth (θ ≈ 20°, R > 98%) for both TE and TM polarizations over a wide spectrum band 1.5 μm∼1.6 μm. Furthermore, it is found by rigorous coupled wave analysis that the polarization-independent reflector proposed here is tolerant of a deviation of grating thickness, which makes it very easy to fabricate in experiments. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Measuring c-quark polarization in W+c samples at ATLAS and CMS

CERN Document Server

Kats, Yevgeny

2016-01-01

The process $pp \\to W^-c$ produces polarized charm quarks. The polarization is expected to be partly retained in $\\Lambda_c$ baryons when those form in the $c$-quark hadronization. We argue that it will likely be possible for ATLAS and CMS to measure the $\\Lambda_c$ polarization in the $W$+$c$ samples in Run 2 of the LHC. This can become the first measurement ever of a longitudinal polarization of charm quarks. Its results will provide a unique input to the understanding of polarization transfer in fragmentation. They will also allow applying the same measurement technique to other (e.g., new physics) samples of charm quarks in which the polarization is a priori unknown. The proposed analysis is similar to the ATLAS and CMS measurements of the $W$+$c$ cross section in the 7 TeV run that used reconstructed $D$-meson decays for charm tagging.

Measuring the influence of aerosols and albedo on sky polarization.

Science.gov (United States)

Kreuter, A; Emde, C; Blumthaler, M

2010-11-01

All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05-0.5 and 0.1-0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error.

Oxygen ion transference number of doped lanthanum gallate

Science.gov (United States)

Wang, Shizhong; Wu, Lingli; Gao, Jie; He, Qiong; Liu, Meilin

The transference numbers for oxygen ion (t O) in several LaGaO 3-based materials are determined from oxygen concentration cells using the materials as the electrolyte, including La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5). Analysis indicates that the accuracy in determination of oxygen ion transference number depends on the electrode polarization resistances of the concentration cell as well as the transport properties of the materials studied. For example, the ratio of open cell voltage to Nernst potential is a good approximation to the ionic transference number for LSGM8282. However, this approximation is no longer adequate for LSGMC5 and LSGMC8.5; the effect of electrode polarization resistances must be taken into consideration in estimation of the ionic transference numbers. In particular, the ionic transference number for LSGMC5 is as high as 0.99, suggesting that it is a promising electrolyte material for low-temperature solid-state electrochemical applications.

VCS-SSA Mainz Experiment. Measurement of the beam spin asymmetry in (e polarized p {yields} ep{gamma}) and (e polarized p {yields} ep{pi}{sup 0}). Final analysis - MEMO I

Energy Technology Data Exchange (ETDEWEB)

Fonvieille, H.; Bensafa, I. [LPC-Clermont-Fd, Universite Blaise Pascal, F-63170 Aubiere Cedex (France)

2006-02-15

This note gives details on the final analysis of the VCS-SSA experiment in terms of Beam Spin Asymmetry. It summarizes the changes between the first and second pass analysis. Then the measured asymmetry is presented for both channels e polarized p {yields} ep{gamma} and e polarized p {yields} ep{pi}{sup 0} including systematic studies. The final experimental result is briefly compared to some model predictions. (authors)

Polarization measurement for internal polarized gaseous targets

International Nuclear Information System (INIS)

Ye Zhenyu; Ye Yunxiu; Lv Haijiang; Mao Yajun

2004-01-01

The authors present an introduction to internal polarized gaseous targets, polarization method, polarization measurement method and procedure. To get the total nuclear polarization of hydrogen atoms (including the polarization of the recombined hydrogen molecules) in the target cell, authors have measured the parameters relating to atomic polarization and polarized hydrogen atoms and molecules. The total polarization of the target during our measurement is P T =0.853 ± 0.036. (authors)

Experimental determination of the degree of polarization of quantum states

DEFF Research Database (Denmark)

Kothe-Termén, Christian; Madsen, Lars Skovgaard; Andersen, Ulrik Lund

2013-01-01

We demonstrate experimental excitation-manifold-resolved polarization characterization of quantum states of light ranging from the few-photon to the many-photon level. In contrast to the traditional characterization of polarization that is based on the Stokes parameters, we experimentally determine...... the Stokes vector of each excitation manifold separately. Only for states with a given photon number do the methods coincide. For states with an indeterminate photon number, for example Gaussian states, the employed method gives a richer and more accurate description. We apply the method both in theory...

Diurnal and seasonal occurrence of polar patches

Directory of Open Access Journals (Sweden)

A. S. Rodger

1996-05-01

Full Text Available Analysis of the diurnal and seasonal variation of polar patches, as identified in two years of HF-radar data from Halley, Antarctica during a period near sunspot maximum, shows that there is a broad maximum in occurrence centred about magnetic noon, not local noon. There are minima in occurrence near midsummer and midwinter, with maxima in occurrence between equinox and winter. There are no significant correlations between the occurrence of polar patches and the corresponding hourly averages of the solar wind and IMF parameters, except that patches usually occur when the interplanetary magnetic field has a southward component. The results can be understood in terms of UT and seasonal differences in the plasma concentration being convected from the dayside ionosphere into the polar cap. In summer and winter the electron concentrations in the polar cap are high and low, respectively, but relatively unstructured. About equinox, a tongue of enhanced ionisation is convected into the polar cap; this tongue is then structured by the effects of the interplanetary magnetic field, but these Halley data cannot be used to separate the various competing mechanisms for patch formation. The observed diurnal and seasonal variation in the occurrence of polar patches are largely consistent with predictions of Sojka et al. (1994 when their results are translated into the southern hemisphere. However, the ionospheric effects of flux transfer events are still considered essential in their formation, a feature not yet included in the Sojka et al. model.

The new polarized neutron reflectometer in Juelich

International Nuclear Information System (INIS)

Ruecker, U.; Alefeld, B.; Bergs, W.; Kentzinger, E.; Brueckel, T.

1999-01-01

On the basis of the HADAS spectrometer in the guide hall of the Juelich research reactor FRJ-2 a polarized neutron reflectometer is build with a 2D-position sensitive detector system. The new spectrometer is optimized for reflectivity and diffuse magnetic scattering measurements with small incident angles on thin magnetic films with thicknesses in the nm range. The polarization analyzer covers the whole detector area, so that a range of 2.5 deg in the scattering angle can be measured simultaneously. The analyzer consists of a stack of supermirrors tilted against the scattering plane. In this reflection geometry, the momentum transfer resolution of the instrument is not reduced, but the sample height is limited to 17 mm. For the monochromator, polarizer and collimation different setups have been compared on the basis of Monte-Carlo calculations: a focusing elliptical supermirror monochromator, a cylindrical mirror, a focusing pyrolytic graphite double monochromator and a double monochromator with bent perfect Si crystals. (author)

Recent progress on HYSPEC, and its polarization analysis capabilities

Directory of Open Access Journals (Sweden)

Winn Barry

2015-01-01

Full Text Available HYSPEC is a high-intensity, direct-geometry time-of-flight spectrometer at the Spallation Neutron Source, optimized for measurement of excitations in small single-crystal specimens with optional polarization analysis capabilities. The incident neutron beam is monochromated using a Fermi chopper with short, straight blades, and is then vertically focused by Bragg scattering onto the sample position by either a highly oriented pyrolitic graphite (unpolarized or a Heusler (polarized crystal array. Neutrons are detected by a bank of 3He tubes that can be positioned over a wide range of scattering angles about the sample axis. HYSPEC entered the user program in February 2013 for unpolarized experiments, and is already experiencing a vibrant research program. Polarization analysis will be accomplished by using the Heusler crystal array to polarize the incident beam, and either a 3He spin filter or a supermirror wide-angle polarization analyser to analyse the scattered beam. The 3He spin filter employs the spin-exchange optical pumping technique. A 60∘ wide angle 3He cell that matches the detector coverage will be used for polarization analysis. The polarized gas in the post-sample wide angle cell is designed to be periodically and automatically refreshed with an adjustable pressure of polarized gas, optically pumped in a separate cell and then transferred to the wide angle cell. The supermirror analyser has 960 supermirror polarizers distributed over 60∘, and has been characterized at the Swiss Spallation Neutron Source. The current status of the instrument and the development of its polarization analysis capabilities are presented.

Theory of radiative transfer in a strong magnetic field

Energy Technology Data Exchange (ETDEWEB)

Kanno, S [Ibaraki Univ., Mito (Japan). Dept. of Physics

1975-07-01

A theory is presented of the radiative transfer in a magnetized plasma with the opacity determined by the Thomson scattering. The Thomson cross section in the magnetic field is highly anisotropic and polarization-dependent. In order to cope with this situation, it is found useful to deal directly with the scattering amplitude (2x2 matrix in the polarization vector space) rather than the intensity. In this way it is possible to take into account the coherent superposition of the forward multiple-scattering amplitudes as a photon propagates. The equation of transfer is established accordingly and approximate solutions are found in the limits of small and large optical thickness. The latter solution is used to find the intensity and the polarization of thermal X-rays from a magnetic dipole star. The concept of mean free path is discussed and also it is shown that the Faraday rotation naturally comes about as a result of the multiple forward scattering.

Influence of aerosols, clouds, and sunglint on polarization spectra of Earthshine

Science.gov (United States)

Emde, Claudia; Buras-Schnell, Robert; Sterzik, Michael; Bagnulo, Stefano

2017-08-01

Context. Ground-based observations of the Earthshine, I.e., the light scattered by Earth to the Moon, and then reflected back to Earth, simulate space observations of our planet and represent a powerful benchmark for the studies of Earth-like planets. Earthshine spectra are strongly linearly polarized, owing to scattering by molecules and small particles in the atmosphere of the Earth and surface reflection, and may allow us to measure global atmospheric and surface properties of planet Earth. Aims: We aim to interpret already published spectropolarimetric observations of the Earthshine by comparing them with new radiative transfer model simulations including a fully realistic three-dimensional (3D) surface-atmosphere model for planet Earth. Methods: We used the highly advanced Monte Carlo radiative transfer model MYSTIC to simulate polarized radiative transfer in the atmosphere of the Earth without approximations regarding the geometry, taking into account the polarization from surface reflection and multiple scattering by molecules, aerosol particles, cloud droplets, and ice crystals. Results: We have shown that Earth spectropolarimetry is highly sensitive to all these input parameters, and we have presented simulations of a fully realistic Earth atmosphere-surface model including 3D cloud fields and two-dimensional (2D) surface property maps. Our modeling results show that scattering in high ice water clouds and reflection from the ocean surface are crucial to explain the continuum polarization at longer wavelengths as has been reported in Earthshine observations taken at the Very Large Telescope in 2011 (3.8% and 6.6% at 800 nm, depending on which part of Earth was visible from the Moon at the time of the observations). We found that the relatively high degree of polarization of 6.6% can be attributed to light reflected by the ocean surface in the sunglint region. High ice-water clouds reduce the amount of absorption in the O2A band and thus explain the weak O2

Probing the Accretion Geometry of Black Holes with X-Ray Polarization

Science.gov (United States)

Schnitman, Jeremy D.

2011-01-01

In the coming years, new space missions will be able to measure X-ray polarization at levels of 1% or better in the approx.1-10 keV energy band. In particular, X-ray polarization is an ideal tool for determining the nature of black hole (BH) accretion disks surrounded by hot coronae. Using a Monte Carlo radiation transport code in full general relativity, we calculate the spectra and polarization features of these BH systems. At low energies, the signal is dominated by the thermal flux coming directly from the optically thick disk. At higher energies, the thermal seed photons have been inverse-Compton scattered by the corona, often reflecting back off the disk before reaching the observer, giving a distinctive polarization signature. By measuring the degree and angle of this X-ray polarization, we can infer the BH inclination, the emission geometry of the accretion flow, and also determine the spin of the black hole.

Plasmonic non-concentric nanorings array as an unidirectional nano-optical conveyor belt actuated by polarization rotation.

Science.gov (United States)

Jiang, Min; Wang, Guanghui; Jiao, Wenxiang; Ying, Zhoufeng; Zou, Ningmu; Ho, Ho-Pui; Sun, Tianyu; Zhang, Xuping

2017-01-15

We report a nano-optical conveyor belt containing an array of gold plasmonic non-concentric nanorings (PNNRs) for the realization of trapping and unidirectional transportation of nanoparticles through rotating the polarization of an excitation beam. The location of hot spots within an asymmetric plasmonic nanostructure is polarization dependent, thus making it possible to manipulate a trapped target by rotating the incident polarization state. In the case of PNNR, the two poles have highly unbalanced trap potential. This greatly enhances the chance of transferring trapped particles between adjacent PNNRs in a given direction through rotating the polarization. As confirmed by three-dimensional finite-difference time-domain analysis, an array of PNNRs forms an unidirectional nano-optical conveyor belt, which delivers target nanoparticles or biomolecules over a long distance with nanometer accuracy. With the capacity to trap and to transfer, our design offers a versatile scheme for conducting mechanical sample manipulation in many on-chip optofluidic applications.

Spin dependent fragmentation functions for heavy flavor baryons and single heavy hyperon polarization

CERN Document Server

Goldstein, G R

2001-01-01

Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. $\\Lambda_b$ , $\\Lambda_c$ and $\\Xi_c$ production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted $\\Lambda_c$ polarization is roughly in agreement with experiment.

Light in Condensed Matter in the Upper Atmosphere as the Origin of Homochirality: Circularly Polarized Light from Rydberg Matter

Science.gov (United States)

Holmlid, Leif

2009-08-01

Clouds of the condensed excited Rydberg matter (RM) exist in the atmospheres of comets and planetary bodies (most easily observed at Mercury and the Moon), where they surround the entire bodies. Vast such clouds are recently proposed to exist in the upper atmosphere of Earth (giving rise to the enormous features called noctilucent clouds, polar mesospheric clouds, and polar mesospheric summer radar echoes). It has been shown in experiments with RM that linearly polarized visible light scattered from an RM layer is transformed to circularly polarized light with a probability of approximately 50%. The circular Rydberg electrons in the magnetic field in the RM may be chiral scatterers. The magnetic and anisotropic RM medium acts as a circular polarizer probably by delaying one of the perpendicular components of the light wave. The delay process involved is called Rabi-flopping and gives delays of the order of femtoseconds. This strong effect thus gives intense circularly polarized visible and UV light within RM clouds. Amino acids and other chiral molecules will experience a strong interaction with this light field in the upper atmospheres of planets. The interaction will vary with the stereogenic conformation of the molecules and in all probability promote the survival of one enantiomer. Here, this strong effect is proposed to be the origin of homochirality. The formation of amino acids in the RM clouds is probably facilitated by the catalytic effect of RM.

Light in condensed matter in the upper atmosphere as the origin of homochirality: circularly polarized light from Rydberg matter.

Science.gov (United States)

Holmlid, Leif

2009-01-01

Clouds of the condensed excited Rydberg matter (RM) exist in the atmospheres of comets and planetary bodies (most easily observed at Mercury and the Moon), where they surround the entire bodies. Vast such clouds are recently proposed to exist in the upper atmosphere of Earth (giving rise to the enormous features called noctilucent clouds, polar mesospheric clouds, and polar mesospheric summer radar echoes). It has been shown in experiments with RM that linearly polarized visible light scattered from an RM layer is transformed to circularly polarized light with a probability of approximately 50%. The circular Rydberg electrons in the magnetic field in the RM may be chiral scatterers. The magnetic and anisotropic RM medium acts as a circular polarizer probably by delaying one of the perpendicular components of the light wave. The delay process involved is called Rabi-flopping and gives delays of the order of femtoseconds. This strong effect thus gives intense circularly polarized visible and UV light within RM clouds. Amino acids and other chiral molecules will experience a strong interaction with this light field in the upper atmospheres of planets. The interaction will vary with the stereogenic conformation of the molecules and in all probability promote the survival of one enantiomer. Here, this strong effect is proposed to be the origin of homochirality. The formation of amino acids in the RM clouds is probably facilitated by the catalytic effect of RM.

Production of strange neutral particles and measurement of the polarization of {lambda} in the NOMAD experiment at CERN; Etude de la production des particules neutres etranges et mesure de la polarisation du {lambda} dans l'experience NOMAD au CERN

Energy Technology Data Exchange (ETDEWEB)

Lachaud, C

2000-05-01

The experiment NOMAD (CERN) is dedicated to the study of the neutrino-nucleon interaction. In these interactions many strange particles are produced: particularly K{sub s}{sup 0}, {lambda} and {lambda}-bar that are more easily detectable and this work is dedicated to them. The study of the polarization of {lambda} allows to go back to the measurements of spin transfer that are not well known. The identification of strange particles is difficult, 2 methods have been used in this work: likelihood ratios and {alpha}-asymmetry method. Once neutral strange particles were identified, their production rate (global and differential) have been made out, K{sup *{+-}}, and {sigma}{sup *{+-}} resonances and the decay of {xi} have been revealed. The second part of this work deals with the measurement of {lambda} polarization. The quality of the reconstruction of events and the cumulated statistics data allowed to give an accurate value of {lambda} polarization. A thorough study of the transverse polarization has been made and we see a dependence of the transverse impulse of {lambda} on the hadronic jet similar to that observed in hadronic collisions.

Estimation of land-atmosphere energy transfer over the Tibetan Plateau by a combination use of geostationary and polar-orbiting satellite data

Science.gov (United States)

Zhong, L.; Ma, Y.

2017-12-01

Land-atmosphere energy transfer is of great importance in land-atmosphere interactions and atmospheric boundary layer processes over the Tibetan Plateau (TP). The energy fluxes have high temporal variability, especially in their diurnal cycle, which cannot be acquired by polar-orbiting satellites alone because of their low temporal resolution. Therefore, it's of great practical significance to retrieve land surface heat fluxes by a combination use of geostationary and polar orbiting satellites. In this study, a time series of the hourly LST was estimated from thermal infrared data acquired by the Chinese geostationary satellite FengYun 2C (FY-2C) over the TP. The split window algorithm (SWA) was optimized using a regression method based on the observations from the Enhanced Observing Period (CEOP) of the Asia-Australia Monsoon Project (CAMP) on the Tibetan Plateau (CAMP/Tibet) and Tibetan observation and research platform (TORP), the land surface emissivity (LSE) from the Moderate Resolution Imaging Spectroradiometer (MODIS), and the water vapor content from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) project. The 10-day composite hourly LST data were generated via the maximum value composite (MVC) method to reduce the cloud effects. The derived LST was validated by the field observations of CAMP/Tibet and TORP. The results show that the retrieved LST and in situ data have a very good correlation (with root mean square error (RMSE), mean bias (MB), mean absolute error (MAE) and correlation coefficient (R) values of 1.99 K, 0.83 K, 1.71 K, and 0.991, respectively). Together with other characteristic parameters derived from polar-orbiting satellites and meteorological forcing data, the energy balance budgets have been retrieved finally. The validation results showed there was a good consistency between estimation results and in-situ measurements over the TP, which prove the robustness of the proposed estimation

Electron-spin polarization in tunnel junctions with ferromagnetic EuS barriers

International Nuclear Information System (INIS)

Hao, X.; Moodera, J.S.; Meservey, R.

1989-01-01

The authors report here spin-polarized tunneling experiments using non-ferromagnetic electrodes and ferromagnetic EuS barriers. Because of the conduction band in EuS splits into spin-up and spin-down subbands when the temperature is below 16.7 K, the Curie temperature of EuS, the tunnel barrier for electrons with different spin directions is different, therefore giving rise to tunnel current polarization. The spin-filter effect, as it may be called, was observed earlier, directly or indirectly, by several groups: Esaki et al. made a tunneling study on junctions having EuS and EuSe barriers; Thompson et al. studied Schottky barrier tunneling between In and doped EuS; Muller et al. and Kisker et al. performed electron field emission experiments on EuS-coated tungsten tips. The field emission experiments gave a maximum polarization of (89 + 7)% for the emitted electrons. Although the previous tunneling studies did not directly show electron polarization, their results were explained by the same spin- filter effect. This work uses the spin-polarized tunneling technique to show directly that tunnel current is indeed polarized and polarization can be as high as 85%

Proton transfer dynamics in a polar nanodroplet: ESIPT of 4'-n,n-dimethylamino-3-hydroxyflavone in AOT/alkane/water reverse micelles

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Deborin [Department of Chemistry, University College of Science & Technology, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009 (India); Batuta, Shaikh; Begum, Naznin Ara [Bio-Organic Chemistry Lab, Department of Chemistry, Visva-Bharati University, Santiniketan 731 235 (India); Mandal, Debabrata, E-mail: dmandal.chemistry@gmail.com [Department of Chemistry, University College of Science & Technology, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009 (India)

2017-04-15

The excited state intramolecular proton transfer (ESIPT) of the well-known fluorophore 4'-N,N-Dimethylamino-3-hydroxyflavone (DMA3HF) was studied in AOT/n-heptane/water reverse micelle solutions. For DMA3HF molecules located inside the AOT encapsulated polar nanodroplets, ESIPT from excited enol (E*) to tautomer (T*) forms was markedly inhibited, yielding time-constants of ≥100 ps, and followed the same trend as solvent relaxation when the ratio W= [H{sub 2}O]/[AOT] was varied. At W=0, the DMA3HF molecules were attached to the ionic AOT headgroups via strong intermolecular H-bonding, which hindered ESIPT. Addition of water changes the situation radically: water molecules form stronger H-bonds with AOT headgroups, displacing the DMA3HF, which are instead engaged in intermolecular H-bonded complexes of the type [DMA3HF···water]. ESIPT of these complex-bound fluorophores involves substantial rearrangement of H-bonding, and is coupled to solvation dynamics. With increasing W-value, solvation becomes faster, and so does ESIPT, reducing the yield of E* species. At the same time, the local environment within the nanodroplets become more more polar with gradual accumulation of water, which causes a monotonic red-shift of the E* emission peak.

How It's Made - Polarized Proton Beam (444th Brookhaven Lecture)

International Nuclear Information System (INIS)

Zelenski, Anatoli

2008-01-01

Experiments with polarized beams at RHIC will provide fundamental tests of QCD, and the electro-weak interaction reveal the spin structure of the proton. Polarization asymmetries and parity violation are the strong signatures for identification of the fundamental processes, which are otherwise inaccessible. Such experiments require the maximum available luminosity and therefore polarization must be obtained as an extra beam quality without sacrificing intensity. There are proposals to polarize the high-energy proton beam in the storage rings by the Stern-Gerlach effect or spin-filter techniques. But so far, the only practically available option is acceleration of the polarized beam produced in the source and taking care of polarization survival during acceleration and storage. Two major innovations -- the 'Siberian Snake' technique for polarization preservation during acceleration and high current polarized proton sources make spin physics with the high-energy polarized beams feasible. The RHIC is the first high-energy collider, where the 'Siberian Snake' technique allowed of polarized proton beam acceleration up-to 250 GeV energy. The RHIC unique Optically Pumped Polarized Ion Source produces sufficient polarized beam intensity for complete saturation of the RHIC acceptance. This polarization technique is based on spin-transfer collisions between a proton or atomic hydrogen beam of a few keV beam energy and optically pumped alkali metal vapors. From the first proposal and feasibility studies to the operational source this development can be considered as example of successful unification of individual scientists ingenuity, international collaboration and modern technology application for creation of a new polarization technique, which allowed of two-to-three order of magnitude polarized beam intensity increase sufficient for loading the RHIC to its full capacity for polarization studies.

7Li breakup polarization potential at near barrier energies

International Nuclear Information System (INIS)

Lubian, J. . E-mail lubian@if.uff.br; Correa, T.; Paes, B.; Figueira, J.M.; Abriola, D.; Fernandez Niello, J.O.; Arazi, A.; Capurro, O.A.; de Barbara, E.; Marti, G.V.; Martinez Heinmann, D.; Negri, A.E.; Pacheco, A.J.; Padron, I.; Gomes, P.R.S.

2007-01-01

Inelastic and one neutron transfer cross sections at energies around the Coulomb barrier were used to derive dynamic polarization potential (DPP) for the 7 Li + 27 Al system. The DPP due to breakup, obtained in a simple way, indicates that its real part is repulsive at near barrier energies

A Monte Carlo Study of Lambda Hyperon Polarization at BM@N

Science.gov (United States)

Suvarieva, D.; Gudima, K.; Zinchenko, A.

2018-03-01

Heavy strange objects (hyperons) can provide essential signatures of the excited and compressed baryonic matter. At NICA, it is planned to study hyperons both in the collider mode (MPD detector) and the fixed-target one (BM@N setup). Measurements of strange hyperon polarization can give additional information on the strong interaction mechanisms. In heavy-ion collisions, such measurements are even more valuable since the polarization is expected to be sensitive to characteristics of the QCD medium (vorticity, hydrodynamic helicity) and to QCD anomalous transport. In this analysis, the possibility to measure at BM@N the polarization of the lightest strange hyperon Λ is studied in Monte Carlo event samples of Au + Au collisions produced with the DCM-QGSM generator. It is shown that the detector will allow to measure polarization with a precision required to check the model predictions.

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

Directory of Open Access Journals (Sweden)

Wang Tong

2017-07-01

Full Text Available We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs, achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1–100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

Science.gov (United States)

Wang, Tong; Puchtler, Tim J.; Patra, Saroj K.; Zhu, Tongtong; Ali, Muhammad; Badcock, Tom J.; Ding, Tao; Oliver, Rachel A.; Schulz, Stefan; Taylor, Robert A.

2017-07-01

We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs), achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1-100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR

Energy Technology Data Exchange (ETDEWEB)

Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G., E-mail: rgg@mit.edu [Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2013-12-07

We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization—suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

Production of strange neutral particles and measurement of the polarization of {lambda} in the NOMAD experiment at CERN; Etude de la production des particules neutres etranges et mesure de la polarisation du {lambda} dans l'experience NOMAD au CERN

Energy Technology Data Exchange (ETDEWEB)

Lachaud, C

2000-05-01

The experiment NOMAD (CERN) is dedicated to the study of the neutrino-nucleon interaction. In these interactions many strange particles are produced: particularly K{sub s}{sup 0}, {lambda} and {lambda}-bar that are more easily detectable and this work is dedicated to them. The study of the polarization of {lambda} allows to go back to the measurements of spin transfer that are not well known. The identification of strange particles is difficult, 2 methods have been used in this work: likelihood ratios and {alpha}-asymmetry method. Once neutral strange particles were identified, their production rate (global and differential) have been made out, K{sup *{+-}}, and {sigma}{sup *{+-}} resonances and the decay of {xi} have been revealed. The second part of this work deals with the measurement of {lambda} polarization. The quality of the reconstruction of events and the cumulated statistics data allowed to give an accurate value of {lambda} polarization. A thorough study of the transverse polarization has been made and we see a dependence of the transverse impulse of {lambda} on the hadronic jet similar to that observed in hadronic collisions.

The giving standard: conditional cooperation in the case of charitable giving

NARCIS (Netherlands)

P. Wiepking (Pamala); M. Heijnen (Merijn)

2011-01-01

textabstractIn this study, we make a first attempt to investigate the mechanisms of conditional cooperation in giving outside experiments, using retrospective survey data on charitable giving (the Giving the Netherlands Panel Study 2005 (GINPS05, 2005 ; N  = 1474)). Our results show that in the case

Detecting the Spectrum of the Atlantic's Thermo-haline Circulation: Deconvolved Climate Proxies Show How Polar Climates Communicate

Science.gov (United States)

Reischmann, Elizabeth; Yang, Xiao; Rial, José

2014-05-01

Deconvolution is widely used in a wide variety of scientific fields, including its significant use in seismology, as a tool to recover real input from a system's impulse response and output. Our research uses spectral division deconvolution in the context of studying the impulse response of the possible relationship between the nonlinear climates of the Polar Regions by using select δ18O ice cores from both poles. This is feasible in spite of the fact that the records may be the result of nonlinear processes because the two polar climates are synchronized for the period studied, forming a Hilbert transform pair. In order to perform this analysis, the age models of three Greenland and four Antarctica records have been matched using a Monte Carlo method with the methane-matched pair GRIP and BYRD as a basis of calculations. For all of the twelve resulting pairs, various deconvolutions schemes (Weiner, Damped Least Squares, Tikhonov, Truncated Singular Value Decomposition) give consistent, quasi-periodic, impulse responses of the system. Multitaper analysis then demonstrates strong, millennia scale, quasi-periodic oscillations in these system responses with a range of 2,500 to 1,000 years. However, these results are directionally dependent, with the transfer function from north to south differing from that of south north. High amplitude power peaks at 5,000 to 1,7000 years characterize the former, while the latter contains peaks at 2,500 to 1,700 years. These predominant periodicities are also found in the data, some of which have been identified as solar forcing, but others of which may indicate internal oscillations of the climate system (1.6-1.4ky). The approximately 1,500 year period transfer function, which does not have a corresponding solar forcing, may indicate one of these internal periodicities of the system, perhaps even indicating the long-term presence of the Deep Water circulation, also known as the thermo-haline circulation (THC). Simplified models of

Exploring the Effects of Cloud Vertical Structure on Cloud Microphysical Retrievals based on Polarized Reflectances

Science.gov (United States)

Miller, D. J.; Zhang, Z.; Platnick, S. E.; Ackerman, A. S.; Cornet, C.; Baum, B. A.

2013-12-01

A polarized cloud reflectance simulator was developed by coupling an LES cloud model with a polarized radiative transfer model to assess the capabilities of polarimetric cloud retrievals. With future remote sensing campaigns like NASA's Aerosols/Clouds/Ecosystems (ACE) planning to feature advanced polarimetric instruments it is important for the cloud remote sensing community to understand the retrievable information available and the related systematic/methodical limitations. The cloud retrieval simulator we have developed allows us to probe these important questions in a realistically relevant test bed. Our simulator utilizes a polarized adding-doubling radiative transfer model and an LES cloud field from a DHARMA simulation (Ackerman et al. 2004) with cloud properties based on the stratocumulus clouds observed during the DYCOMS-II field campaign. In this study we will focus on how the vertical structure of cloud microphysics can influence polarized cloud effective radius retrievals. Numerous previous studies have explored how retrievals based on total reflectance are affected by cloud vertical structure (Platnick 2000, Chang and Li 2002) but no such studies about the effects of vertical structure on polarized retrievals exist. Unlike the total cloud reflectance, which is predominantly multiply scattered light, the polarized reflectance is primarily the result of singly scattered photons. Thus the polarized reflectance is sensitive to only the uppermost region of the cloud (tau~influencer on the microphysical development of cloud droplets, can be potentially studied with polarimetric retrievals.

Magnetic materials research with polarized neutrons

International Nuclear Information System (INIS)

Hammer, J.; Rauch, H.; Badurek, G.

1980-01-01

In order to study the mechanisms of time dependent effects in magnetic materials with superparamagnetic or spinglass behaviour as well as in ferromagnetic materials a 'dynamic neutron depolarization' system has been developed as a beam hole experiment at the TRIGA Mark II Reactor in Vienna. In the course of this experiment an increasing or decreasing polarization can be observed as a consequence of the interaction between spins of the polarized neutron beam and the magnetic structure if the magnetic clusters in the sample are stimulated by a short magnetic pulse, lasting up to a few seconds. In accordance with numerical calculations and theoretical considerations we can draw conclusions from dynamics in the range of 10 ms to 1 h within magnetic materials which give us additional information that cannot be obtained from experiments used so far

Broadband polarized emission from P(NDI2OD-T2) polymer.

Science.gov (United States)

Ulrich, Steve; Sutch, Tabitha; Szulczewski, Greg; Schweizer, Matthias; Barbosa, Newton; Araujo, Paulo

2018-05-18

We investigate the P(NDI2OD-T2) photophysical properties via absorbance and fluorescence spectroscopy, in association with the experimental approach baptized Stokes Spectroscopy, which provides valuable material information through the acquisition and analysis of the fluorescence polarization degree. By changing solvents and using different samples such as solutions, thick, and thin films, it is possible to control the polarization degree spectrum associated to the fluorescence emitted by the polymer's isolated chains and aggregates. We show that the polarization degree could become a powerful tool to obtain information related to the samples morphology, which is connected to their microscopic structure. Moreover, the polarization degree spectra suggest that depolarization effects linked to energy and charge transfer mechanisms are likely taking place. Our findings indicate that P(NDI2OD-T2) polymers are excellent candidates for the advancement of organic technologies that rely on the emission and detection of polarized lights. © 2018 IOP Publishing Ltd.

Polarized tagged photons

International Nuclear Information System (INIS)

Maximon, L.C.; Ganz, Eric; Aniel, Thierry; Miniac, Arlette de.

1982-03-01

We consider in detail the differential cross section for polarized bremsstrahlung for angles and energies in the range of interest for a tagging system and derive a high energy, small angle approximation for this cross section. We use these approximations to determine the maxima and minima of the cross sections for these two polarization states, dσperpendicular and dσparallel, and to evaluate these cross sections at the extrema. It is shown that both dσperpendicular and dσparallel have a very sharp dip in the region of small momentum transfers. However, their behavior in the region of the dip, as a function of the azimuthal angle phi, is quite different over most of the photon spectrum. The cross section dσperpendicular behaves similarly to the cross section for unpolarized photons in that as phi increases, the sharp dip vanishes, the minimum fuses with the second maximum, and the cross section then has only a single maximum. In contrast, the sharp dip in the cross section dσparallel remains as phi increases. Coulomb corrections to the Born approximation are considered, and do not fill in these dips

Polarized parton distributions from charged-current deep-inelastic scattering and future neutrino factories

CERN Document Server

Forte, Stefano; Ridolfi, G; Forte, Stefano; Mangano, Michelangelo L.; Ridolfi, Giovanni

2001-01-01

We discuss the determination of polarized parton distributions from charged-current deep-inelastic scattering experiments. We summarize the next-to-leading order treatment of charged-current polarized structure functions, their relation to polarized parton distributions and scale dependence, and discuss their description by means of a next-to-leading order evolution code. We discuss current theoretical expectations and positivity constraints on the unmeasured C-odd combinations Delta q-Delta qbar of polarized quark distributions, and their determination in charged-current deep-inelastic scattering experiments. We give estimates of the expected errors on charged-current structure functions at a future neutrino factory, and perform a study of the accuracy in the determination of polarized parton distributions that would be possible at such a facility. We show that these measurements have the potential to distinguish between different theoretical scenarios for the proton spin structure.

Polarized parton distributions from charged-current deep-inelastic scattering and future neutrino factories

International Nuclear Information System (INIS)

Forte, Stefano; Mangano, Michelangelo L.; Ridolfi, Giovanni

2001-01-01

We discuss the determination of polarized parton distributions from charged-current deep-inelastic scattering experiments. We summarize the next-to-leading-order treatment of charged-current polarized structure functions, their relation to polarized parton distributions and scale dependence, and discuss their description by means of a next-to-leading-order evolution code. We discuss current theoretical expectations and positivity constraints on the unmeasured C-odd combinations Δq-Δq-bar of polarized quark distributions, and their determination in charged-current deep-inelastic scattering experiments. We give estimates of the expected errors on charged-current structure functions at a future neutrino factory, and perform a study of the accuracy in the determination of polarized parton distributions that would be possible at such a facility. We show that these measurements have the potential to distinguish between different theoretical scenarios for the proton spin structure

Optically enhanced nuclear cross polarization in acridine-doped fluorene

Energy Technology Data Exchange (ETDEWEB)

Oshiro, C.M.

1982-06-01

The objective of this work has been to create large polarizations of the dilute /sup 13/C nuclei in the solid state. The idea was to create /sup 1/H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the /sup 13/C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large /sup 1/H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large /sup 13/C polarizations have been created in fluorene single crystals. These large /sup 13/C polarizations have permitted the determination of the seven incongruent chemical shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined.

Optically enhanced nuclear cross polarization in acridine-doped fluorene

International Nuclear Information System (INIS)

Oshiro, C.M.

1982-06-01

The objective of this work has been to create large polarizations of the dilute 13 C nuclei in the solid state. The idea was to create 1 H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the 13 C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large 1 H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large 13 C polarizations have been created in fluorene single crystals. These large 13 C polarizations have permitted the determination of the seven incongruent chemical shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined

Simple model for polar cap convection patterns and generation of theta auroras

International Nuclear Information System (INIS)

Lyons, L.R.

1985-01-01

The simple addition of a uniform interplanetary magnetic field and the Earth's dipole magnetic field is used to evaluate electric field convection patterns over the polar caps that result from solar wind flow across open geomagnetic field lines. This model is found to account for observed polar-cap convection patterns as a function of the interplanetary magnetic field components B/sub y/ and B/sub z/. In particular, the model offers an explanation for sunward and antisunward convection over the polar caps for B/sub z/>0. Observed field-aligned current patterns within the polar cap and observed auroral arcs across the polar cap are also explained by the model. In addition, the model gives several predictions concerning the polar cap that should be testable. Effects of solar wind pressure and magnetospheric currents on magnetospheric electric and magnetic fields are neglected. That observed polar cap features are reproduced suggests that the neglected effects do not modify the large-scale topology of magnetospheric electric and magnetic fields along open polar cap field lines. Of course, the neglected effects significantly modify the magnetic geometry, so that the results of this paper are not quantitatively realistic and many details may be incorrect. Nevertheless, the model provides a simple explanation for many qualitative features of polar cap convection

Radical cations of quadricyclane and norbornadiene in polar ZSM-5 matrices: Radical cation photochemical transformations without photons

International Nuclear Information System (INIS)

Barnabas, M.V.; Trifunac, A.D.

1994-01-01

Radical cations of quadricyclane (Q) and norbornadiene (NBD) are produced by γ-radiolysis in zeolites. In polar ZSM-5, only one radical cation is initially observed below 100K. Increasing the temperature above 200K gives rise to the cyclopentadiene radical cation. Higher temperatures (>360K) give rise to the cyclopenten-4-yl radical. The observation of cyclopentadiene radical cation implies the occurrence of the reverse Diels-Alder reaction. This is a thermally forbidden, photochemically allowed, process, which is made possible by the interaction of the polar zeolite matrix sites with parent NBD and Q radical cations

Measurement of Polarization Observables in the Electro-Excitation of the Proton to its First Excited State

International Nuclear Information System (INIS)

Rikki Roche

2003-01-01

This thesis reports results from the Thomas Jefferson National Accelerator Facility (Jefferson Lab) Hall A experiment E91-011, which measured double-polarization observables in the pion electroproduction reaction from the proton. Specifically, the experiment measured the recoil proton polarization, polarized response functions, and cross section for the p(rvec e), e(prime) (rvec p) π o reaction at a center-of-mass energy centered at W = 1232 MeV--the peak of the Δ(1232) resonance--and at a four-momentum transfer squared of Q 2 = 1.0 GeV 2 /c 2 . Both the recoil proton polarization and polarized response function results will be presented in this thesis

Polarization imaging enhancement for target vision through haze

Science.gov (United States)

Wu, Hai-Ying; Zhang, San-Xi; Li, Jie; LI, Bin; Tang, Zi-li; Liu, Biao; Jia, Wen-Wu

2016-10-01

Haze, fog, and smoke are turbid medium in the atmosphere which usually degrade viewing condition of outdoor scenes. The resulted images lose contrast and color fidelity with serious degradation. Due to loss of large detailed information of measured scene, it will usually lead to invalid detection and measurement. The suspended particles in the atmosphere and the scene being measured give rise to polarization changes by their reflection. In the process of reflection, absorption and scattering, the object itself can be determined by its own polarization characteristics. Based on this point, we proposed an approach for target vision through haze. This approach is based on the polarization differences between the scene being measured and the scattering background to move the haze effects. It can realize a great visibility enhancement and enable the scene rendering even if imaged under restricted viewing conditions with low polarization. In this work, the detailed theoretical operation principle is presented. A validating imaging system is established and the corresponding experiment is carried out. We present the experimental results of haze-free image of scene with recovered high contrast. This method also can be used to effectively enhance the imaging performance of any other optical system.

B polarization of the CMB from Faraday rotation

International Nuclear Information System (INIS)

Scoccola, Claudia; Harari, Diego; Mollerach, Silvia

2004-01-01

We study the effect of Faraday rotation due to a uniform magnetic field on the polarization of the cosmic microwave background. Scalar fluctuations give rise only to parity-even E-type polarization of the cosmic microwave background. However in the presence of a magnetic field, a nonvanishing parity-odd B-type polarization component is produced through Faraday rotation. We derive the exact solution for the E and B modes generated by scalar perturbations including the Faraday rotation effect of a uniform magnetic field, and evaluate their cross correlations with temperature anisotropies. We compute the angular autocorrelation function of the B-modes in the limit that the Faraday rotation is small. We find that uniform primordial magnetic fields of present strength around B 0 =10 -9 G rotate E-modes into B-modes with amplitude comparable to those due to the weak gravitational lensing effect at frequencies around ν=30 GHz. The strength of B-modes produced by Faraday rotation scales as B 0 /ν 2 . We evaluate also the depolarizing effect of Faraday rotation upon the cross correlation between temperature anisotropy and E-type polarization

Oxygen ion transference number of doped lanthanum gallate

Energy Technology Data Exchange (ETDEWEB)

Wang, Shizhong; Wu, Lingli; Gao, Jie; He, Qiong [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Meilin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

2008-12-01

The transference numbers for oxygen ion (t{sub O}) in several LaGaO{sub 3}-based materials are determined from oxygen concentration cells using the materials as the electrolyte, including La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM8282), La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3-{delta}} (LSGMC5) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.115}Co{sub 0.085}O{sub 3-{delta}} (LSGMC8.5). Analysis indicates that the accuracy in determination of oxygen ion transference number depends on the electrode polarization resistances of the concentration cell as well as the transport properties of the materials studied. For example, the ratio of open cell voltage to Nernst potential is a good approximation to the ionic transference number for LSGM8282. However, this approximation is no longer adequate for LSGMC5 and LSGMC8.5; the effect of electrode polarization resistances must be taken into consideration in estimation of the ionic transference numbers. In particular, the ionic transference number for LSGMC5 is as high as 0.99, suggesting that it is a promising electrolyte material for low-temperature solid-state electrochemical applications. (author)

Macroscopic polarization in crystalline dielectrics: the geometric phase approach

International Nuclear Information System (INIS)

Resta, R.

1994-01-01

The macroscopic electric polarization of a crystal is often defined as the dipole of a unit cell. In fact, such a dipole moment is ill defined, and the above definition is incorrect. Looking more closely, the quantity generally measured is differential polarization, defined with respect to a ''reference state'' of the same material. Such differential polarizations include either derivatives of the polarization (dielectric permittivity, Born effective charges, piezoelectricity, pyroelectricity) or finite differences (ferroelectricity). On the theoretical side, the differential concept is basic as well. Owing to continuity, a polarization difference is equivalent to a macroscopic current, which is directly accessible to the theory as a bulk property. Polarization is a quantum phenomenon and cannot be treated with a classical model, particularly whenever delocalized valence electrons are present in the dielectric. In a quantum picture, the current is basically a property of the phase of the wave functions, as opposed to the charge, which is a property of their modulus. An elegant and complete theory has recently been developed by King-Smith and Vanderbilt, in which the polarization difference between any two crystal states--in a null electric field--takes the form of a geometric quantum phase. This gives a comprehensive account of this theory, which is relevant for dealing with transverse-optic phonons, piezoelectricity, and ferroelectricity. Its relation to the established concepts of linear-response theory is also discussed. Within the geometric phase approach, the relevant polarization difference occurs as the circuit integral of a Berry connection (or ''vector potential''), while the corresponding curvature (or ''magnetic field'') provides the macroscopic linear response

Polarized 3He Gas Circulating Technologies for Neutron Analyzers

Energy Technology Data Exchange (ETDEWEB)

Watt, David [Xemed LLC, Durham, NH (United States); Hersman, Bill [Xemed LLC, Durham, NH (United States)

2014-12-10

We describe the development of an integrated system for quasi-continuous operation of a large volume neutron analyzer. The system consists of a non-magnetic diaphragm compressor, a prototype large volume helium polarizer, a surrogate neutron analyzer, a non-depolarizing gas storage reservoir, a non-ferrous valve manifold for handling gas distribution, a custom rubidium-vapor gas return purifier, and wire-wound transfer lines, all of which are immersed in a two-meter external magnetic field. Over the Phase II period we focused on three major tasks required for the successful deployment of these types of systems: 1) design and implementation of gas handling hardware, 2) automation for long-term operation, and 3) improvements in polarizer performance, specifically fabrication of aluminosilicate optical pumping cells. In this report we describe the design, implementation, and testing of the gas handling hardware. We describe improved polarizer performance resulting from improved cell materials and fabrication methods. These improvements yielded valved 8.5 liter cells with relaxation times greater than 12 hours. Pumping this cell with 1500W laser power with 1.25nm linewidth yielded peak polarizations of 60%, measured both inside and outside the polarizer. Fully narrowing this laser to 0.25nm, demonstrated separately on one stack of the four, would have allowed 70% polarization with this cell. We demonstrated the removal of 5 liters of polarized helium from the polarizer with no measured loss of polarization. We circulated the gas through a titanium-clad compressor with polarization loss below 3% per pass. We also prepared for the next phase of development by refining the design of the polarizer so that it can be engineer-certified for pressurized operation. The performance of our system far exceeds comparable efforts elsewhere.

First measurement of the electric formfactor of the neutron in the exclusive quasielastic scattering of polarized electrons from polarized 3He

International Nuclear Information System (INIS)

Meyerhoff, M.; Eyl, D.; Frey, A.; Andresen, H.G.; Annand, J.R.M.; Aulenbacher, K.; Becker, J.; Blume-Werry, J.; Dombo, T.; Drescher, P.; Ducret, J.E.; Fischer, H.; Grabmayr, P.; Hall, S.; Hartmann, P.; Hehl, T.; Heil, W.; Hoffmann, J.; Kellie, J.D.; Klein, F.; Leduc, M.; Moeller, H.; Nachtigall, C.; Ostrick, M.; Otten, E.W.; Owens, R.O.; Pluetzer, S.; Reichert, E.; Rohe, D.; Schaefer, M.; Schearer, L.D.; Schmieden, H.; Steffens, K.; Surkau, R.; Walcher, T.

1995-01-01

A first measurement of the asymmetry in quasielastic scattering of longitudinally polarized electrons from a polarized 3 He gas target in coincidence with the knocked out neutron is reported. This measurement was made feasible by the cw beam of the 855 meV Mainz Microtron MAMI. It allows a determination of the electric formfactor of the neutron G n E independent of binding effects to first order. At bar Q 2 =0.31 (GeV/c) 2 two asymmetries bar A parallel (rvec S He parallel rvec q) and bar A perpendicular (rvec S He perpendicular rvec q) have been measured giving bar A parallel =(-7.40±0.73%) and bar A perpendicular =(0.89±0.30)%. The ratio bar A perpendicular /bar A parallel is independent of the absolute value of the electron and target polarization and yields G n E =0.035±0.012±0.005. copyright 1995 American Institute of Physics

Photo-Induced Electron Spin Polarization in a Narrow Band Gap Semiconductor Nanostructure

International Nuclear Information System (INIS)

Peter, A. John; Lee, Chang Woo

2012-01-01

Photo-induced spin dependent electron transmission through a narrow gap InSb/InGa x Sb 1−x semiconductor symmetric well is theoretically studied using transfer matrix formulism. The transparency of electron transmission is calculated as a function of electron energy for different concentrations of gallium. Enhanced spin-polarized photon assisted resonant tunnelling in the heterostructure due to Dresselhaus and Rashba spin-orbit coupling induced splitting of the resonant level and compressed spin-polarization are observed. Our results show that Dresselhaus spin-orbit coupling is dominant for the photon effect and the computed polarization efficiency increases with the photon effect and the gallium concentration

Long-Lifetime Low-Scatter Neutron Polarization Target

International Nuclear Information System (INIS)

Richardson, Jonathan M.

2004-01-01

Polarized neutrons scattering is an important technology for characterizing magnetic and other materials. Polarized helium three (P-3He) is a novel technology for creating polarized beams and, perhaps more importantly, for the analysis of polarization in highly divergent scattered beams. Analysis of scattered beams requires specialized targets with complex geometries to ensure accurate results. Special materials and handling procedures are required to give the targets a long useful lifetime. In most cases, the targets must be shielded from stray magnetic fields from nearby equipment. SRL has developed and demonstrated hybrid targets made from glass and aluminum. We have also developed and calibrated a low-field NMR system for measuring polarization lifetimes. We have demonstrated that our low-field system is able to measure NMR signals in the presence of conducting (metallic) cell elements. We have also demonstrated a non-magnetic valve that can be used to seal the cells. We feel that these accomplishments in Phase I are sufficient to ensure a successful Phase II program. The commercial market for this technology is solid. There are over nine neutron scattering centers in the US and Canada and over 22 abroad. Currently, the US plans to build a new $1.4B scattering facility called the Spallation Neutron Source (SNS). The technology developed in this project will allow SRL to supply targets to both existing and future facilities. SRL is also involved with the application of P-3He to medical imaging

Theoretical aspects of electron transfer reactions of complex molecules

DEFF Research Database (Denmark)

Kuznetsov, A. M.; Ulstrup, Jens

2001-01-01

Features of electron transfer involving complex molecules are discussed. This notion presently refers to molecular reactants where charge transfer is accompanied by large molecular reorganization, and commonly used displaced harmonic oscillator models do not apply. It is shown that comprehensive...... theory of charge transfer in polar media offers convenient tools for the treatment of experimental data for such systems, with due account of large-amplitude strongly anharmonic intramolecular reorganization. Equations for the activation barrier and free energy relationships are provided, incorporating...

Negative circular polarization emissions from WSe2/MoSe2 commensurate heterobilayers

KAUST Repository

Hsu, Wei-Ting; Lu, Li-Syuan; Wu, Po-Hsun; Lee, Ming-Hao; Chen, Peng-Jen; Wu, Pei-Ying; Chou, Yi-Chia; Jeng, Horng-Tay; Li, Lain-Jong; Chu, Ming-Wen; Chang, Wen-Hao

2018-01-01

Van der Waals heterobilayers of transition metal dichalcogenides with spin-valley coupling of carriers in different layers have emerged as a new platform for exploring spin/valleytronic applications. The interlayer coupling was predicted to exhibit subtle changes with the interlayer atomic registry. Manually stacked heterobilayers, however, are incommensurate with the inevitable interlayer twist and/or lattice mismatch, where the properties associated with atomic registry are difficult to access by optical means. Here, we unveil the distinct polarization properties of valley-specific interlayer excitons using epitaxially grown, commensurate WSe/MoSe heterobilayers with well-defined (AA and AB) atomic registry. We observe circularly polarized photoluminescence from interlayer excitons, but with a helicity opposite to the optical excitation. The negative circular polarization arises from the quantum interference imposed by interlayer atomic registry, giving rise to distinct polarization selection rules for interlayer excitons. Using selective excitation schemes, we demonstrate the optical addressability for interlayer excitons with different valley configurations and polarization helicities.

Negative circular polarization emissions from WSe2/MoSe2 commensurate heterobilayers

KAUST Repository

Hsu, Wei-Ting

2018-04-11

Van der Waals heterobilayers of transition metal dichalcogenides with spin-valley coupling of carriers in different layers have emerged as a new platform for exploring spin/valleytronic applications. The interlayer coupling was predicted to exhibit subtle changes with the interlayer atomic registry. Manually stacked heterobilayers, however, are incommensurate with the inevitable interlayer twist and/or lattice mismatch, where the properties associated with atomic registry are difficult to access by optical means. Here, we unveil the distinct polarization properties of valley-specific interlayer excitons using epitaxially grown, commensurate WSe/MoSe heterobilayers with well-defined (AA and AB) atomic registry. We observe circularly polarized photoluminescence from interlayer excitons, but with a helicity opposite to the optical excitation. The negative circular polarization arises from the quantum interference imposed by interlayer atomic registry, giving rise to distinct polarization selection rules for interlayer excitons. Using selective excitation schemes, we demonstrate the optical addressability for interlayer excitons with different valley configurations and polarization helicities.

Effect of solvent polarity and temperature on the spectral and thermodynamic properties of exciplexes of 1-cyanonaphthalene with hexamethylbenzene in organic solvents

International Nuclear Information System (INIS)

Asim, Sadia; Mansha, Asim; Grampp, Günter; Landgraf, Stephan; Zahid, Muhammad; Bhatti, Ijaz Ahmad

2014-01-01

Study of the effect of solvent polarity and temperature is done on the exciplex emission spectra of 1-cyanonaphthalene with hexamethylbenzene. Exciplex system is studied in the range of partially polar solvents and in solvent mixture of propyl acetate and butyronitrile. The unique feature of this solvent mixture is that only the solvent polarity changes (6.0≤ε s ≤24.7) with the change in the mole fraction of solvents whereas the solvent viscosity and refractive index remains unaffected. Thermodynamic properties are calculated according to the models developed by Weller and Kuzmin. Fluorescence lifetimes for both the fluorophore as well as the exciplex are evaluated in all used solvents. Exciplex energetics as a function of solvent polarity and temperature are also discussed. Kuzmin model of self-consistent polarization is used for the explanation of the exciplex emission spectra. The effects of solvent polarity and temperature on energy of zero–zero transitions (hv 0 / ), Huang–Rhys factor (S), Gauss broadening of vibronic level (σ) and the dominant high-frequency vibration (hν ν ) are investigated. The strong dependence of exciplex stability and energetics upon the solvent polarity and temperature are observed. Full charge transfer exciplexes were observed in solvents of all polarities and stronger exciplex with large emission intensities were found in solvents of low polarities but with the increase in solvent polarity the exciplex becomes weak and they dissociate fastly into radical ion pairs. The kinetic model of Kuzmin was observed to reduce into the Weller kinetic model for this exciplex system with ∆G ET = −0.22 eV and the spectral shift, h∆ν>0.2 eV. - Highlights: • Exciplex formed as a result of mixing of charge transfer and locally excited states. • Effect of solvents polarity and temperature on the exciplex stability and thermodynamics. • Solvent polarity will decide the formation of contact radical ion pair or solvent separated

Proceedings of the 3rd US-Japan Workshop on Plasma Polarization Spectroscopy

International Nuclear Information System (INIS)

Beiersdorfer, P; Flyimoto, T

2002-01-01

The third US-Japan Workshop on Plasma Polarization Spectroscopy was held at the Lawrence Livermore National Laboratory in Livermore, California, on June 18-21, 2001. The talks presented at this workshop are summarized in these proceedings. The papers cover both experimental investigation and applications of plasma polarization spectroscopy as well as the theoretical foundation and formalisms to understand and describe the polarization phenomena. The papers give an overview of the history of plasma polarization spectroscopy, derive the formal aspects of polarization spectroscopy, including the effects of electric and magnetic fields, discuss spectra perturbed by intense microwave fields, charge exchange, and dielectronic recombination, and present calculations of various collisional excitation and ionization cross sections and the modeling of plasma polarization spectroscopy phenomena. Experimental results are given from the WT-3 tokamak, the MST reverse field pinch, the Large Helical Device, the GAMMA 10 mirror machine, the Nevada Terrawatt Facility, the Livermore EBIT-II electron beam ion trap, and beam-foil spectroscopy. In addition, results were presented from studies of several laser-produced plasma experiments and new instrumental techniques were demonstrated

np Elastic-scattering experiments with polarized neutron beams

International Nuclear Information System (INIS)

Chalmers, J.S.; Ditzler, W.R.; Hill, D.

1985-01-01

Measurements of the spin transfer parameters, K/sub NN/ and K/sub LL/, at 500, 650, and 800 MeV are presented for the reaction p-vector d → n-vector pp at 0 0 . The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction is a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV. Measurements of np elastic scattering observables C/sub LL/ and C/sub SL/ covering 35 0 to 172 0 are performed using a polarized neutron beam at 500, 650, and 800 MeV. Preliminary results are presented. 3 refs., 6 figs

Polarization spectrum of supernova 1987A interpreted in terms of shape asymmetry

Energy Technology Data Exchange (ETDEWEB)

Jeffery, D J

1987-10-01

Polarimetry carried out on the type II supernova 1987A on 6 and 7 March 1987 showed variation in polarization across line profiles. This polarization structure is interpreted as arising from an asymmetric, homologously expanding, scattering atmosphere surrounding an asymmetric continuum-producing photosphere. Resonant scattering of radiation by ions in the atmosphere produces the line structure in the flux spectrum and polarizes the emergent radiation. The asymmetric shape of the atmosphere causes a non-zero net polarization. Sobolev-method radiative transfer calculations with axisymmetric oblate ellipsoidal models have been carried out to fit the observed data. The models are parameterized by the ratio of the symmetry axis to the perpendicular axis, c/a. The fits to the 1987A data indicate that (c/a) is approx. 0.6-0.8.

Semileptonic weak and electromagnetic interactions in nuclei: recoil polarization in muon capture

International Nuclear Information System (INIS)

Rosenfelder, R.

1979-01-01

An analysis of the polarization of the recoiling nucleus following the capture of polarized muons by nuclei is performed. New general expressions for arbitrary nuclear spin are obtained in terms of the same reduced matrix elements which govern inelastic electron scattering and β-decay. As an application the A = 12 system is considered and uncertainties in the nuclear structure are studied by using different sets of one-body density matrices. With the canonical values of the weak form factors (i.e. absence of second-class currents) a fairly good agreement with the experimental data is achieved including the inelastic form factor at high momentum transfers and the recently measured average 12 B polarization. Implications of the new corrected value of the average polarization on weak form factors and nuclear structure are discussed. (Auth.)

Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

Energy Technology Data Exchange (ETDEWEB)

Guo, Yongling [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Bo, Maolin [Yangtze Normal University, College of Mechanical and Electrical Engineering, Chongqing 408100 (China); Wang, Yan [School of Information and Electronic Engineering, Hunan University of Science and Technology, Hunan 411201 (China); Liu, Yonghui [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Sun, Chang Q. [NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Huang, Yongli, E-mail: huangyongli@xtu.edu.cn [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China)

2017-02-28

Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O{sup 2−} lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta{sup +} electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta{sup +}; the sp{sup 3}-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent

Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

International Nuclear Information System (INIS)

Guo, Yongling; Bo, Maolin; Wang, Yan; Liu, Yonghui; Sun, Chang Q.; Huang, Yongli

2017-01-01

Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O"2"− lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta"+ electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta"+; the sp"3-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent insight into the

Optically initialized robust valley-polarized holes in monolayer WSe2

KAUST Repository

Hsu, Wei-Ting

2015-11-25

A robust valley polarization is a key prerequisite for exploiting valley pseudospin to carry information in next-generation electronics and optoelectronics. Although monolayer transition metal dichalcogenides with inherent spin–valley coupling offer a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time-resolved Kerr rotation spectroscopy, we observe a long-lived valley polarization for positive trion with a lifetime approaching 1 ns at low temperatures, which is much longer than the trion recombination lifetime (~10–20 ps). The long-lived valley polarization arises from the transfer of valley pseudospin from photocarriers to resident holes in a specific valley. The optically initialized valley pseudospin of holes remains robust even at room temperature, which opens up the possibility to realize room-temperature valleytronics based on transition metal dichalcogenides.

Building Transferable Knowledge and Skills through an Interdisciplinary Polar Science Graduate Program

Science.gov (United States)

Culler, L. E.; Virginia, R. A.; Albert, M. R.; Ayres, M.

2015-12-01

Modern graduate education must extend beyond disciplinary content to prepare students for diverse careers in science. At Dartmouth, a graduate program in Polar Environmental Change uses interdisciplinary study of the polar regions as a core from which students develop skills and knowledge for tackling complex environmental issues that require cooperation across scientific disciplines and with educators, policy makers, and stakeholders. Two major NSF-funded initiatives have supported professional development for graduate students in this program, including an IGERT (Integrative Graduate Education and Research Traineeship) and leadership of JSEP's (Joint Science Education Project) Arctic Science Education Week in Greenland. We teach courses that emphasize the links between science and the human dimensions of environmental change; host training sessions in science communication; invite guest speakers who work in policy, academia, journalism, government research, etc.; lead an international field-based training that includes policy-focused meetings and a large outreach component; provide multiple opportunities for outreach and collaboration with local schools; and build outreach and education into graduate research programs where students instruct and mentor high school students. Students from diverse scientific disciplines (Ecology, Earth Science, and Engineering) participate in all of the above, which significantly strengthens their interdisciplinary view of polar science and ability to communicate across disciplines. In addition, graduate students have developed awareness, confidence, and the skills to pursue and obtain diverse careers. This is reflected in the fact that recent graduates have acquired permanent and post-doctoral positions in academic and government research, full-time teaching, and also in post-docs focused on outreach and science policy. Dartmouth's interdisciplinary approach to graduate education is producing tomorrow's leaders in science.

The impact of Faraday effects on polarized black hole images of Sagittarius A*.

Science.gov (United States)

Jiménez-Rosales, Alejandra; Dexter, Jason

2018-05-01

We study model images and polarization maps of Sagittarius A* at 230 GHz. We post-process GRMHD simulations and perform a fully relativistic radiative transfer calculation of the emitted synchrotron radiation to obtain polarized images for a range of mass accretion rates and electron temperatures. At low accretion rates, the polarization map traces the underlying toroidal magnetic field geometry. At high accretion rates, we find that Faraday rotation internal to the emission region can depolarize and scramble the map. We measure the net linear polarization fraction and find that high accretion rate "jet-disc" models are heavily depolarized and are therefore disfavoured. We show how Event Horizon Telescope measurements of the polarized "correlation length" over the image provide a model-independent upper limit on the strength of these Faraday effects, and constrain plasma properties like the electron temperature and magnetic field strength.

Measurements of Polarization Transfers in Real Compton Scattering by a proton target at JLAB. A new source of information on the 3D shape of the nucleon

Energy Technology Data Exchange (ETDEWEB)

Fanelli, Cristiano V. [Sapienza Univ. of Rome (Italy)

2015-03-01

In this thesis work, results of the analysis of the polarization transfers measured in real Compton scattering (RCS) by the Collaboration E07-002 at the Je fferson Lab Hall-C are presented. The data were collected at large scattering angle (theta_cm = 70deg) and with a polarized incident photon beam at an average energy of 3.8 GeV. Such a kind of experiments allows one to understand more deeply the reaction mechanism, that involves a real photon, by extracting both Compton form factors and Generalized Parton Distributions (GPDs) (also relevant for possibly shedding light on the total angular momentum of the nucleon). The obtained results for the longitudinal and transverse polarization transfers K_LL and K_LT, are of crucial importance, since they confirm unambiguously the disagreement between experimental data and pQCD prediction, as it was found in E99-114 experiment, and favor the Handbag mechanism. The E99-114 and E07-002 results can contribute to attract new interest on the great yield of the Compton scattering by a nucleon target, as demonstrated by the recent approval of an experimental proposal submitted to the Jefferson Lab PAC 42 for a Wide-angle Compton Scattering experiment, at 8 and 10 GeV Photon Energies. The new experiments approved to run with the updated 12 GeV electron beam at JLab, are characterized by much higher luminosities, and a new GEM tracker is under development to tackle the challenging backgrounds. Within this context, we present a new multistep tracking algorithm, based on (i) a Neural Network (NN) designed for a fast and efficient association of the hits measured by the GEM detector which allows the track identification, and (ii) the application of both a Kalman filter and Rauch-Tung-Striebel smoother to further improve the track reconstruction. The full procedure, i.e. NN and filtering, appears very promising, with high performances in terms of both association effciency and reconstruction accuracy, and these preliminary results will

Light scattering reviews 7 radiative transfer and optical properties of atmosphere and underlying surface

CERN Document Server

Kokhanovsky, Alexander A

2014-01-01

This book describes modern advances in radiative transfer and light scattering. Coverage includes fast radiative transfer techniques, use of polarization in remote sensing and recent developments in remote sensing of snow properties from space observations.

Polarization Signatures of Kink Instabilities in the Blazar Emission Region from Relativistic Magnetohydrodynamic Simulations

International Nuclear Information System (INIS)

Zhang, Haocheng; Taylor, Greg; Li, Hui; Guo, Fan

2017-01-01

Kink instabilities are likely to occur in the current-carrying magnetized plasma jets. Recent observations of the blazar radiation and polarization signatures suggest that the blazar emission region may be considerably magnetized. While the kink instability has been studied with first-principle magnetohydrodynamic (MHD) simulations, the corresponding time-dependent radiation and polarization signatures have not been investigated. In this paper, we perform comprehensive polarization-dependent radiation modeling of the kink instability in the blazar emission region based on relativistic MHD (RMHD) simulations. We find that the kink instability may give rise to strong flares with polarization angle (PA) swings or weak flares with polarization fluctuations, depending on the initial magnetic topology and magnetization. These findings are consistent with observations. Compared with the shock model, the kink model generates polarization signatures that are in better agreement with the general polarization observations. Therefore, we suggest that kink instabilities may widely exist in the jet environment and provide an efficient way to convert the magnetic energy and produce multiwavelength flares and polarization variations.

Polarization Signatures of Kink Instabilities in the Blazar Emission Region from Relativistic Magnetohydrodynamic Simulations

Energy Technology Data Exchange (ETDEWEB)

Zhang, Haocheng; Taylor, Greg [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States); Li, Hui; Guo, Fan [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2017-02-01

Kink instabilities are likely to occur in the current-carrying magnetized plasma jets. Recent observations of the blazar radiation and polarization signatures suggest that the blazar emission region may be considerably magnetized. While the kink instability has been studied with first-principle magnetohydrodynamic (MHD) simulations, the corresponding time-dependent radiation and polarization signatures have not been investigated. In this paper, we perform comprehensive polarization-dependent radiation modeling of the kink instability in the blazar emission region based on relativistic MHD (RMHD) simulations. We find that the kink instability may give rise to strong flares with polarization angle (PA) swings or weak flares with polarization fluctuations, depending on the initial magnetic topology and magnetization. These findings are consistent with observations. Compared with the shock model, the kink model generates polarization signatures that are in better agreement with the general polarization observations. Therefore, we suggest that kink instabilities may widely exist in the jet environment and provide an efficient way to convert the magnetic energy and produce multiwavelength flares and polarization variations.

Target recognition of log-polar ladar range images using moment invariants

Science.gov (United States)

Xia, Wenze; Han, Shaokun; Cao, Jie; Yu, Haoyong

2017-01-01

The ladar range image has received considerable attentions in the automatic target recognition field. However, previous research does not cover target recognition using log-polar ladar range images. Therefore, we construct a target recognition system based on log-polar ladar range images in this paper. In this system combined moment invariants and backpropagation neural network are selected as shape descriptor and shape classifier, respectively. In order to fully analyze the effect of log-polar sampling pattern on recognition result, several comparative experiments based on simulated and real range images are carried out. Eventually, several important conclusions are drawn: (i) if combined moments are computed directly by log-polar range images, translation, rotation and scaling invariant properties of combined moments will be invalid (ii) when object is located in the center of field of view, recognition rate of log-polar range images is less sensitive to the changing of field of view (iii) as object position changes from center to edge of field of view, recognition performance of log-polar range images will decline dramatically (iv) log-polar range images has a better noise robustness than Cartesian range images. Finally, we give a suggestion that it is better to divide field of view into recognition area and searching area in the real application.

Transfer of property inter vivos : chapter 7

NARCIS (Netherlands)

van Vliet, Lars

2017-01-01

This chapter will give an overview of the various transfer systems for movable property and immovable property. It will focus on voluntary transfers based on a legal act between the transferor and transferee. First the difference between the unitary approach and the functional approach to passing of

Human disturbances of denning polar bears in Alaska

International Nuclear Information System (INIS)

Amstrup, S.C.

1993-01-01

Polar bears (Ursus maritimus) give birth in dens of snow and ice. The altricial neonates cannot leave the den for >2 months post-partum and are potentially vulnerable to disturbances near dens. The coastal plain (1002) area of Alaska's Arctic National Wildlife Refuge (ANWR) lies in a region of known polar bear denning and also may contain >9 billion barrels of recoverable oil. Polar bears in dens could be affected in many ways by hydrocarbon development. The distribution of dens on ANWR was documented between 1981 and 1992 and responses of bears in dens to various anthropogenic disturbances were observed. Of 44 dens located by radiotelemetry on the mainland coast of Alaska and Canada, 20 (45%) were on ANWR and 15 (34%) were within the 1002 area. Thus, development of ANWR will increase the potential that denning polar bears are disturbed by human activities. However, perturbations resulting from capture, marking, and radiotracking maternal bears did not affect litter sizes or stature of cubs produced. Likewise, 10 of 12 denned polar bears tolerated exposure to exceptional levels of activity. This tolerance and the fact that investment in the denning effort increases through the winter indicated that spatial and temporal restrictions on developments could prevent the potential for many disruptions of denned bears from being realized. 16 refs., 1 fig., 2 tabs

Synthesis of modified polymer inclusion membranes for photo-electrodeposition of cadmium using polarized electrodes

Energy Technology Data Exchange (ETDEWEB)

Yahia Cherif, Asma [Laboratory of Hydrometallurgy and Inorganic Molecular Chemistry, Faculty of Chemistry, USTHB, BP 32 El Alia, 16111, Algiers (Algeria); Arous, Omar, E-mail: omararous@yahoo.fr [Laboratory of Hydrometallurgy and Inorganic Molecular Chemistry, Faculty of Chemistry, USTHB, BP 32 El Alia, 16111, Algiers (Algeria); Center of Research in Physical and Chemical Analysis CRAPC, BP 248 Algiers, RP 16004, Algiers (Algeria); Amara, Mourad [Laboratory of Hydrometallurgy and Inorganic Molecular Chemistry, Faculty of Chemistry, USTHB, BP 32 El Alia, 16111, Algiers (Algeria); Omeiri, Said [Center of Research in Physical and Chemical Analysis CRAPC, BP 248 Algiers, RP 16004, Algiers (Algeria); Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32 El Alia, 16111, Algiers (Algeria); Kerdjoudj, Hacene [Laboratory of Hydrometallurgy and Inorganic Molecular Chemistry, Faculty of Chemistry, USTHB, BP 32 El Alia, 16111, Algiers (Algeria); Trari, Mohamed [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32 El Alia, 16111, Algiers (Algeria)

2012-08-15

Highlights: Black-Right-Pointing-Pointer Homogeneous PIM membranes containing water soluble polymers have been obtained under new experimental conditions. Black-Right-Pointing-Pointer Photoelectrodeposition of 'Cd' has been carried out using WO{sub 3} and CuFeO{sub 2} as electrode. Black-Right-Pointing-Pointer Using both photo-polarized electrodes enhances transference of cadmium compared to one. Black-Right-Pointing-Pointer Membrane with poly-phosphoric acid (PPA) give a rise of transferred amount of Cd. - Abstract: In this work, we have developed a novel class of polymeric inclusion membranes (PIMs) for the cations separation. The membrane is made up of cellulose triacetate modified by poly-electrolytes (poly-phosphoric acid, polyvinyl pyrolidone, polyacrylic acid, polyvinyl alcohol and poly-anetholsulfonic acid) using 2-hydroxy-5-dodecylbenzaldehyde incorporated into the polymer as carrier and tris ethyl hexyl phosphate or glycerine as plasticizers. Different PIMs are synthesized and characterized by the Fourier transform infrared, X-ray diffraction, thermal analysis and scanning electron microscopy. The influence of the membrane nature is studied using supports with different physical characteristics (porosity, thickness, hydrophobia). As application, the transport of Cd{sup 2+} using PIMs coupled with photo-electrodes is investigated. The photo-catalytic results indicate that the combined system p-CuFeO{sub 2}/membrane/n-WO{sub 3} enhances considerably the electrons transfer toward the delafossite CuFeO{sub 2}. The position of the conduction band of CuFeO{sub 2} is looked to be the key issue for the photo electrochemical Cd{sup 2+} reduction.

Technology transfer from research and development to European industry

International Nuclear Information System (INIS)

Conrads, H.; Theenhaus, R.

1989-01-01

This paper gives an overview of technology transfer, i.e. the transfer of knowledge, insights and technologies from research and development to practical application, especially in the Federal Republic of Germany. Some examples and perspectives of technology transfer for nuclear fusion are given. (author). 7 refs.; 5 figs

Analysis of adiabatic transfer in cavity quantum electrodynamics

Indian Academy of Sciences (India)

adiabatic transfer process through the 'dark state' by a slow variation of the control laser intensity. ... control field of Rabi frequency C(t) transfers one photon in the cavity mode to a long- .... It gives an approximate statistical description of the.

Polarization phenomena in quantum chromodynamics

Energy Technology Data Exchange (ETDEWEB)

Brodsky, S.J. [Stanford Univ., CA (United States)

1994-12-01

The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and nonperturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g{sub A} on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x{sub bj}; (b) consequences of the principle of hadron retention in high x{sub F} inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. The author also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A{sub NN} observed in large angle proton-proton scattering, the anomalously large {rho}{pi} branching ratio of the J/{psi}, and the rapidly changing polarization dependence of both J/{psi} and continuum lepton pair hadroproduction observed at large x{sub F}. The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron.

Polarization phenomena in quantum chromodynamics

International Nuclear Information System (INIS)

Brodsky, S.J.

1994-03-01

The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and non-perturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g A on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x bj ; (b) consequences of the principle of hadron helicity retention in high x F inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. He also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A NN observed in large angle proton-proton scattering, the anomalously large ρπ branching ratio of the J/ψ, and the rapidly changing polarization dependence of both J/ψ and continuum lepton pair hadroproduction observed at large x F . The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron

[Polarized light microscopy for evaluation of oocytes as a prognostic factor in the evolution of a cycle in assisted reproduction].

Science.gov (United States)

González-Ortega, C; Cancino-Villarreal, P; Alonzo-Torres, V E; Martínez-Robles, I; Pérez-Peña, E; Gutiérrez-Gutiérrez, A M

2016-04-01

Identification of the best embryos to transfer is a key element for success in assisted reproduction. In the last decade, several morphological criteria of oocytes and embryos were evaluated with regard to their potential for predicting embryo viability. The introduction of polarization light microscopy systems has allowed the visualization of the meiotic spindle and the different layers of the zona pellucida in human oocytes on the basis of birefringence in a non-destructive way. Conflicting results have been reported regarding the predictive value in ICSI cycles. To assess the predictive ability of meiotic spindle and zona pellucida of human oocytes to implant by polarized microscopy in ICSI cycles. Prospective and observational clinical study. 903 oocytes from 94 ICSI cycles were analyzed with polarized microscopy. Meiotic spindle visualization and zona pellucida birefringence values by polarized microscopy were correlated with ICSI cycles results. Meiotic spindle visualization and birefringence values of zona pellucida decreased in a direct basis with increasing age. In patients aged over the 35 years, the percentage of a visible spindle and mean zona pellucida birefringence was lower than in younger patients. Fertilization rate were higher in oocytes with visible meiotic spindle (81.3% vs. 64%; p vs. 39%; p=0.01). Fertilization rate was higher in oocytes with positive values of birefringence (77.5 % vs. 68.5% p=0.005) with similar embryo quality. Conception cycles showed oocytes with higher mean value of zona birefringence and visible spindle vs. no-conception cycles (pPolarized light microscopy improves oocyte selection, which significantly impacts in the development of embryos with greater implantation potential. The use of polarized light microscopy with sperm selection methods, blastocyst culture and deferred embryo transfers will contribute to transfer fewer embryos without diminishing rates of live birth and single embryo transfer will be more feasible.

Polarization-dependent pump-probe studies in atomic fine-structure levels: towards the production of spin-polarized electrons

International Nuclear Information System (INIS)

Sokell, E.; Zamith, S.; Bouchene, M.A.; Girard, B.

2000-01-01

The precession of orbital and spin angular momentum vectors has been observed in a pump-probe study of the 4P fine-structure states of atomic potassium. A femtosecond pump pulse prepared a coherent superposition of the two fine-structure components. A time-delayed probe pulse then ionized the system after it had been allowed to evolve freely. Oscillations recorded in the ion signal reflect the evolution of the orientation of the orbital and spin angular momentum due to spin-orbit coupling. This interpretation gives physical insight into the cause of the half-period phase shift observed when the relative polarizations of the laser pulses were changed from parallel to perpendicular. Finally, it is shown that these changes in the orientation of the spin momentum vector of the system can be utilized to produce highly spin-polarized free electrons on the femtosecond scale. (author)

Broadband working-waveband-tunable polarization converter based on anisotropic metasurface

Science.gov (United States)

Lin, Yu; Wang, Lei; Gao, Jun; Lu, Yichao; Jiang, Suhua; Zeng, Wei

2017-03-01

We experimentally and theoretically demonstrate an ultrathin, broadband, and highly efficient metamaterial-based polarization converter with a metasurface/insulator/metal (MIM) configuration. In such a system, the resonance undergoes a transition from a vertical Fabry-Pérot type to a transverse type as the spacer thickness decreases. By changing the spacer thickness from 1 to 15 mm, the working waveband of this device could be tuned from 10.9-12.9 to 6-8 GHz without compromising the polarization conversion efficiency. Equivalent circuit theory and the transfer matrix method are used for demonstrating the physical mechanism of our device.

Enhanced Condensation Heat Transfer

Science.gov (United States)

Rose, John Winston

The paper gives some personal observations on various aspects of enhanced condensation heat transfer. The topics discussed are external condensation (horizontal low-finned tubes and wire-wrapped tubes), internal condensation (microfin tubes and microchannels) and Marangoni condensation of binary mixtures.

Detecting Super-Thin Clouds With Polarized Light

Science.gov (United States)

Sun, Wenbo; Videen, Gorden; Mishchenko, Michael I.

2014-01-01

We report a novel method for detecting cloud particles in the atmosphere. Solar radiation backscattered from clouds is studied with both satellite data and a radiative transfer model. A distinct feature is found in the angle of linear polarization of solar radiation that is backscattered from clouds. The dominant backscattered electric field from the clear-sky Earth-atmosphere system is nearly parallel to the Earth surface. However, when clouds are present, this electric field can rotate significantly away from the parallel direction. Model results demonstrate that this polarization feature can be used to detect super-thin cirrus clouds having an optical depth of only 0.06 and super-thin liquid water clouds having an optical depth of only 0.01. Such clouds are too thin to be sensed using any current passive satellite instruments.

Research and development on optically pumped polarized ion sources. Technical progress report, July 1, 1985-June 30, 1986

International Nuclear Information System (INIS)

Anderson, L.W.

1986-07-01

The development of an optically pumped polarized 23 Na target is discussed. The three categories of research are: (1) electron spin relaxation of the 23 Na due to wall collisions; (2) effects of radiation trapping on the polarization that can be produced in an alkali target by optical pumping; and (3) the effects of spin exchange collisions in the polarization of a fast H 0 beam formed by charge transfer as an H + beam passes through a polarized alkali target. 90 refs., 7 figs

Simulations to study the static polarization limit for RHIC lattice

Science.gov (United States)

Duan, Zhe; Qin, Qing

2016-01-01

A study of spin dynamics based on simulations with the Polymorphic Tracking Code (PTC) is reported, exploring the dependence of the static polarization limit on various beam parameters and lattice settings for a practical RHIC lattice. It is shown that the behavior of the static polarization limit is dominantly affected by the vertical motion, while the effect of beam-beam interaction is small. In addition, the “nonresonant beam polarization” observed and studied in the lattice-independent model is also observed in this lattice-dependent model. Therefore, this simulation study gives insights of polarization evolution at fixed beam energies, that are not available in simple spin tracking. Supported by the U.S. Department of Energy (DE-AC02-98CH10886), Hundred-Talent Program (Chinese Academy of Sciences), and National Natural Science Foundation of China (11105164)

Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

Science.gov (United States)

Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

2016-02-01

Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has the potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen-vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarization. We illustrate numerically the effectiveness of the model in a flow cell containing nanodiamonds immobilized in a hydrogel, polarizing flowing water molecules 4700-fold above thermal polarization in a magnetic field of 0.35 T, in volumes detectable by current NMR scanners.

Laser-driven polarized hydrogen and deuterium internal targets

International Nuclear Information System (INIS)

Jones, C.E.; Fedchak, J.A.; Kowalczyk, R.S.

1995-01-01

After completing comprehensive tests of the performance of the source with both hydrogen and deuterium gas, we began tests of a realistic polarized deuterium internal target. These tests involve characterizing the atomic polarization and dissociation fraction of atoms in a storage cell as a function of flow and magnetic field, and making direct measurements of the average nuclear tensor polarization of deuterium atoms in the storage cell. Transfer of polarization from the atomic electron to the nucleus as a result of D-D spin-exchange collisions was observed in deuterium, verifying calculations suggesting that high vector polarization in both hydrogen and deuterium can be obtained in a gas in spin temperature equilibrium without inducing RF transitions between the magnetic substates. In order to improve the durability of the system, the source glassware was redesigned to simplify construction and installation and eliminate stress points that led to frequent breakage. Improvements made to the nuclear polarimeter, which used the low energy 3 H(d,n) 4 He reaction to analyze the tensor polarization of the deuterium, included installing acceleration lenses constructed of wire mesh to improve pumping conductance, construction of a new holding field coil, and elimination of the Wien filter from the setup. These changes substantially simplified operation of the polarimeter and should have reduced depolarization in collisions with the wall. However, when a number of tests failed to show an improvement of the nuclear polarization, it was discovered that extended operation of the system with a section of teflon as a getter for potassium caused the dissociation fraction to decline with time under realistic operating conditions, suggesting that teflon may not be a suitable material to eliminate potassium from the target. We are replacing the teflon surfaces with drifilm-coated ones and plan to continue tests of the polarized internal target in this configuration

Irradiation cryostat for LiH and LiD polarized solid targets

International Nuclear Information System (INIS)

Goertz, S.

1991-01-01

Scattering experiments with polarized nucleon targets are an important tool to understand the nuclear spin structure. Pion photoproduction experiments on polarized protrons and neutrons as well as measurements of the neutron and deuteron formfactors will be performed at ELSA. 7 LiH and 6 LiD seem to be attractive target materials for these experiments, because they offer high proton and deuteron polarisation, respectively. Expecially 6 LiD has further very important advantages compared to the common deuteron target materials as d-Butanol and ND 3 . This work describes the mechanism of DNP (Dynamic Nuclear Polarization) in LiH and LiD and gives a view on the nature of the so-called paramagnetic impurities in these materials. In order to maximize the nuclear polarization, the production of these radicals have to take place under well defined temperature conditions. Therefore the first version of an irradiation cryostat was built and tested in regard to its cooling power and temperature adjustment. (orig.)

Emission-angle and polarization-rotation effects in the lensed CMB

Energy Technology Data Exchange (ETDEWEB)

Lewis, Antony [Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Hall, Alex [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Challinor, Anthony, E-mail: antony@cosmologist.info, E-mail: ahall@roe.ac.uk, E-mail: a.d.challinor@ast.cam.ac.uk [Institute of Astronomy and Kavli Institute for Cosmology, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

2017-08-01

Lensing of the CMB is an important effect, and is usually modelled by remapping the unlensed CMB fields by a lensing deflection. However the lensing deflections also change the photon path so that the emission angle is no longer orthogonal to the background last-scattering surface. We give the first calculation of the emission-angle corrections to the standard lensing approximation from dipole (Doppler) sources for temperature and quadrupole sources for temperature and polarization. We show that while the corrections are negligible for the temperature and E-mode polarization, additional large-scale B-modes are produced with a white spectrum that dominates those from post-Born field rotation (curl lensing). On large scales about one percent of the total lensing-induced B-mode amplitude is expected to be due to this effect. However, the photon emission angle does remain orthogonal to the perturbed last-scattering surface due to time delay, and half of the large-scale emission-angle B modes cancel with B modes from time delay to give a total contribution of about half a percent. While not important for planned observations, the signal could ultimately limit the ability of delensing to reveal low amplitudes of primordial gravitational waves. We also derive the rotation of polarization due to multiple deflections between emission and observation. The rotation angle is of quadratic order in the deflection angle, and hence negligibly small: polarization typically rotates by less than an arcsecond, orders of magnitude less than a small-scale image rotates due to post-Born field rotation (which is quadratic in the shear). The field-rotation B modes dominate the other effects on small scales.

In situ scanning tunneling microscope tip treatment device for spin polarization imaging

Science.gov (United States)

Li, An-Ping [Oak Ridge, TN; Jianxing, Ma [Oak Ridge, TN; Shen, Jian [Knoxville, TN

2008-04-22

A tip treatment device for use in an ultrahigh vacuum in situ scanning tunneling microscope (STM). The device provides spin polarization functionality to new or existing variable temperature STM systems. The tip treatment device readily converts a conventional STM to a spin-polarized tip, and thereby converts a standard STM system into a spin-polarized STM system. The tip treatment device also has functions of tip cleaning and tip flashing a STM tip to high temperature (>2000.degree. C.) in an extremely localized fashion. Tip coating functions can also be carried out, providing the tip sharp end with monolayers of coating materials including magnetic films. The device is also fully compatible with ultrahigh vacuum sample transfer setups.

Role of polarizer-tilting-angle in zero-field spin-transfer nano-oscillators with perpendicular anisotropy

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Fuentes, C.; Gallardo, R. A., E-mail: rodolfo.gallardo@usm.cl; Landeros, P. [Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123 Valparaíso (Chile)

2015-10-05

An analytical model for studying the stability of a single domain ferromagnetic layer under the influence of a spin-polarized current is presented. The theory is applied to bias-field-free nano-oscillators with perpendicular anisotropy, which allows to obtain a polarizer-angle vs. current phase diagram that describes the stability of magnetic states. Explicit formulae for the critical current densities unveil the influence of the relative orientation between free and polarizer layers, allowing the emergence of precessional steady-states, and also the possibility to reduce the magnitude of the threshold current density to produce microwave oscillations. It is shown that oscillating steady-states arise in a broad angular region, and the dependence of their boundaries is fully specified by the model. The reliability of the analytical results has been corroborated by comparison to numerical calculations. Such structures are currently under intense research because of remarkable properties offering new prospects for microwave applications in communication technologies.

Interrogation of orbital structure by elliptically polarized intense femtosecond laser pulses

International Nuclear Information System (INIS)

Abu-samha, M.; Madsen, L. B.

2011-01-01

We solve the three-dimensional time-dependent Schroedinger equation and present investigations of the imprint of the orbital angular node in photoelectron momentum distributions of an aligned atomic p-type orbital following ionization by an intense elliptically polarized laser pulse of femtosecond duration. We investigate the role of light ellipticity and the alignment angle of the major polarization axis of the external field relative to the probed orbital by studying radial and angular momentum distributions, the latter at a fixed narrow interval of final momenta close to the peak of the photoelectron momentum distribution. In general only the angular distributions carry a clear signature of the orbital symmetry. Our study shows that circular polarization gives the most clear imprints of orbital nodes. These findings are insensitive to pulse duration.

The wavelength dependence of polarization in NGC 2023

International Nuclear Information System (INIS)

Rolph, C. D.; Scarrott, S. M.

1989-01-01

NGC 2023 is a bright reflection nebula illuminated by the central star HD37903. At 2 microns the nebula is seen solely by reflected light from the central star but in the NIR there is excess radiation that is supposed to arise from thermal emission from a population of small grains (Sellgren, 1984). The unexpectedly high surface brightness at R and I wavelengths has led to the suggestion that even at these wavelengths there is a significant contribution from this thermal emission process (Witt, Schild, and Kraiman, 1984). If the nebula is seen by reflected starlight then this radiation will be linearly polarized. The level of polarization depends on the scattering geometry, grain size distribution, etc., and is typically 20 to 40 percent for nebulae such as NGC 1999 which is morphologically similar to NGC 2023. If, in any waveband, there is a contribution of radiation from emission processes this radiation will be unpolarized and will serve to dilute the scattered radiation to give a lower level of observed polarization. A study of the wavelength dependence of polarization in nebulae in which there may be thermal emission from grains will indicate the contribution from this process to the total luminosity. Polarization maps were produced in BVRI wavebands for the NGC 2023 nebulosity which confirm that at all wavelengths it is a reflection nebula illuminated by a central star. The wavelength dependence of polarization at representative points in the nebula and in a scatter plot of polarization in V and I wavebands at all points at which measurements are given. Results indicate that throughout the nebula there is a general trend for the level of polarization to increase with wavelength and that maximum levels of polarization occur at the longest wavelengths. No evidence is seen in the data for any significant contribution from the thermal emission from grains in the BVRI luminosity of NGC 2023

Graphene-assisted near-field radiative heat transfer between corrugated polar materials

International Nuclear Information System (INIS)

Liu, X. L.; Zhang, Z. M.

2014-01-01

Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

Surface polarization, rumpling, and domain ordering of strained ultrathin BaTiO_3(001) films with in-plane and out-of-plane polarization

International Nuclear Information System (INIS)

Dionot, Jelle; Mathieu, Claire; Barrett, Nick; Geneste, Gregory

2014-01-01

BaTiO_3 ultrathin films (thickness ≅1.6 nm) with in- and out-of-plane polarization are studied by first-principles calculations. Out-of-plane polarization is simulated using the method proposed by Shimada et al. [Phys. Rev. B 81, 144116 (2010)], which consists in building a supercell containing small domains with alternating up and down polarization. This allows one to investigate the properties of defect free BaTiO_3 ultrathin films with polarization perpendicular to the surface, as a function of in-plane lattice constant, i.e., epitaxial strain. The configurations with polarization perpendicular to the surface (c phase) are found stable under compressive strain, while under tensile strain, the polarization tends to lie in-plane (aa phase), along [110]. In the c phase, the most stable domain width is predicted to be 1 to 2 lattice constants, and the magnitude of the surface rumpling varies according to the direction of the polarization (upwards versus downwards), though its sign is unchanged, the oxygen anions pointing in all cases outwards. Finally, all the surfaces studied are found to be insulating. Analysis of the atom-projected electronic density of states gives insight into the surface contributions to the electronic structure. An important reduction of the Kohn-Sham band gap is predicted at TiO_2 terminations in the c phase (≅1 eV with respect to the aa phase). The Madelung potential at the surface plays the dominant role in modifications of the surface electronic structure. (authors)

Polarized IR-microscope spectra of guanidinium hydrogenselenate single crystal.

Science.gov (United States)

Drozd, M; Baran, J

2005-10-01

The polarized IR-microscope spectra of C(NH2)3.HSeO4 small single crystal samples were measured at room temperature. The spectra are discussed with the framework of oriented gas model approximation and group theory. The stretching nuOH vibration of the hydrogen bond with the O...O distance of 2.616 A gives characteristic broad AB-type absorption in the IR spectra. The changes of intensity of the AB bands in function of polarizer angle are described. Detailed assignment for bands derived from stretching and bending modes of selenate anions and guanidinium cations were performed. The observed intensities of these bands in polarized infrared spectra were correlated with theoretical calculation of directional cosines of selected transition dipole moments for investigated crystal. The vibrational studies seem to be helpful in understanding of physical and chemical properties of described compound and also in design of new complexes with exactly defined behaviors.

Perturbed stationary-state description of the polarization effect in innershell ionization

International Nuclear Information System (INIS)

Basbas, G.; Land, D.J.

1983-01-01

A one-parameter trial initial-state wavefunction correlated to a projectile (polarized) is described and used to calculate innershell ionization cross sections for collisions with heavy charged particles. The variational principle is used to determine the parameter. The minimized energy gives the binding effect as a function of projectile position. Existing codes can be readily adapted to incorporate the trial wavefunction. Comparison with the previous theory of the polarization effect is made. Results for K-shell ionization of titanium by protons in the 0.3 to 2.4 MeV energy range agree with measured values

W-Band Circularly Polarized TE11 Mode Transducer

Science.gov (United States)

Zhan, Mingzhou; He, Wangdong; Wang, Lei

2018-06-01

This paper presents a balanced sidewall exciting approach to realize the circularly polarized TE11 mode transducer. We used a voltage vector transfer matrix to establish the relationship between input and output vectors, then we analyzed amplitude and phase errors to estimate the isolation of degenerate mode. A mode transducer with a sidewall exciter was designed based on the results. In the 88-100 GHz frequency range, the simulated axial ratio is less than 1.05 and the isolation of linearly polarization TE11 mode is higher than 30 dBc. In back-to-back measurements, the return loss is generally greater than 20 dB with a typical insertion loss of 1.2 dB. Back-to-back transmission measurements are in excellent agreement with simulations.

Charge transfers in complex transition metal alloys (Ti2Fe)

International Nuclear Information System (INIS)

Abramovici, G.

1998-01-01

We introduce a new non-orthogonal tight-binding model, for complex alloys, in which electronic structure is characterized by charge transfers. We give the analytic calculation of a charge transfer, in which overlapping two-center terms are rigorously taken into account. Then, we apply numerically this result to an approximant phase of a quasicrystal of Ti 2 Fe alloy. This model is more particularly adapted to transition metals, and gives realistic densities of states. (orig.)

Dynamics of the polar ionosphere structure disturbance in the Svalgaard-Mansurov effect

International Nuclear Information System (INIS)

Osipov, N.K.; Mozhaev, A.M.; Larina, T.N.; Ponomarev, Yu.N.

1988-01-01

Nonstationary disturbance model of the ionsphere of polar caps caused by change of B y component sign of interplanetary magnetic field is considered. It is shown that nonstationary convection transfer of ionospheric plasma represents the main and the most fast mechanism regulating reconstruction of ionosphere structure in polar caps during magnetosphere substorms, caused by the change of B y sign. Calculations show that characteristic time of sufficient change of ionosphere structure at ∼1500 km distances is on the order of 10-25 min

Hardness and softness reactivity kernels within the spin-polarized density-functional theory

International Nuclear Information System (INIS)

Chamorro, Eduardo; De Proft, Frank; Geerlings, Paul

2005-01-01

Generalized hardness and softness reactivity kernels are defined within a spin-polarized density-functional theory (SP-DFT) conceptual framework. These quantities constitute the basis for the global, local (i.e., r-position dependent), and nonlocal (i.e., r and r ' -position dependents) indices devoted to the treatment of both charge-transfer and spin-polarization processes in such a reactivity framework. The exact relationships between these descriptors within a SP-DFT framework are derived and the implications for chemical reactivity in such context are outlined

Mathematical modeling and experimental study of polarization echo in optically anisotropic media

Science.gov (United States)

Bogdanov, Yu. I.; Kalinkin, A. A.; Kulik, S. P.; Moreva, E. V.; Shershulin, V. A.; Belinsky, L. V.

2013-01-01

As optical systems are one of the candidates for implementation of a scalable quantum computer, it is important to develop an adequate method of description of both quantum states of light and operations performed by optical elements. Using the concept of chi-matrix representation of quantum operations and Choi-Jamiolkowski isomorphism we expand Jones calculus to allow description of evolution of mixed polarization states in linear optical systems. The developed method is then used to give a full description of polarization echo effect, which was described in 1 based on an analogy between the effects of polarization optics and spin dynamics. Theoretical predictions are confirmed by reconstructing operations performed by a series of quartz waveplates using quantum process tomography protocols.

Investigating dust trapping in transition disks with millimeter-wave polarization

Science.gov (United States)

Pohl, A.; Kataoka, A.; Pinilla, P.; Dullemond, C. P.; Henning, Th.; Birnstiel, T.

2016-08-01

Context. Spatially resolved polarized (sub-)mm emission has been observed for example in the protoplanetary disk around HL Tau. Magnetically aligned grains are commonly interpreted as the source of polarization. However, self-scattering by large dust grains with a high enough albedo is another polarization mechanism, which is becoming a compelling method independent of the spectral index to constrain the dust grain size in protoplanetary disks. Aims: We study the dust polarization at mm wavelengths in the dust trapping scenario proposed for transition disks, when a giant planet opens a gap in the disk. We investigate the characteristic polarization patterns and their dependence on disk inclination, dust size evolution, planet position, and observing wavelength. Methods: We combine two-dimensional hydrodynamical simulations of planet-disk interactions with self-consistent dust growth models. These size-dependent dust density distributions are used for follow-up three-dimensional radiative transfer calculations to predict the polarization degree at ALMA bands due to scattered thermal emission. Results: Dust self-scattering has been proven to be a viable mechanism for producing polarized mm-wave radiation. We find that the polarization pattern of a disk with a planetary gap after 1 Myr of dust evolution shows a distinctive three-ring structure. Two narrow inner rings are located at the planet gap edges. A third wider ring of polarization is situated in the outer disk beyond 100 au. For increasing observing wavelengths, all three rings change their position slightly, where the innermost and outermost rings move inward. This distance is detectable when comparing the results at ALMA bands 3, 6, and 7. Within the highest polarized intensity regions the polarization vectors are oriented in the azimuthal direction. For an inclined disk there is an interplay between polarization originating from a flux gradient and inclination-induced quadrupole polarization. For

Radiation self-polarization of electrons moving in a magnetic field. [Vector spin operator, relaxation time

Energy Technology Data Exchange (ETDEWEB)

Bagrov, V G; Dorofeev, O F; Sokolov, A A; Ternov, I M; Khalilov, V R [Moskovskij Gosudarstvennyj Univ. (USSR)

1975-03-11

When electrons move in a magnetic field, synchrotron radiation gives rise to transitions accompanied by the electron spin reorientation. In this case, it is essential that the transition probability depends on the spin orientation; as a result electron polarization takes place with the spin orientation being predominantly opposite to the direction of the magnetic field. This effect has been called ''radiative self-polarization of electrons''. The present work is concerned with the question how the choice of the spin operator will affect the self-polarization degree and relaxation time. The problem has been solved for a vector spin operator.

Polarization of lanthanum nucleus by dynamic polarization method

International Nuclear Information System (INIS)

Adachi, Toshikazu; Ishimoto, Shigeru; Masuda, Yasuhiro; Morimoto, Kimio

1989-01-01

Preliminary studies have been carried out concerning the application of a dynamic polarization method to polarizing lanthanum fluoride single crystal to be employed as target in experiments with time reversal invariance. The present report briefly outlines the dynamic polarization method and describes some preliminary studies carried out so far. Dynamic polarization is of particular importance because no techniques are currently available that can produce highly polarized static nucleus. Spin interaction between electrons and protons (nuclei) plays a major role in the dynamic polarization method. In a thermal equilibrium state, electrons are polarized almost completely while most protons are not polarized. Positively polarized proton spin is produced by applying microwave to this system. The most hopeful candidate target material is single crystal of LaF 3 containing neodymium because the crystal is chemically stable and easy to handle. The spin direction is of great importance in experiments with time reversal invariance. The spin of neutrons in the target can be cancelled by adjusting the external magnetic field applied to a frozen polarized target. In a frozen spin state, the polarity decreases slowly with a relaxation time that depends on the external magnetic field and temperature. (N.K.)

Polarization-Dependent Measurements of Molecular Super Rotors with Oriented Angular Momenta

Science.gov (United States)

Murray, Matthew J.; Toro, Carlos; Liu, Qingnan; Mullin, Amy S.

2014-05-01

Controlling molecular motion would enable manipulation of energy flow between molecules. Here we have used an optical centrifuge to investigate energy transfer between molecular super rotors with oriented angular momenta. The polarizable electron cloud of the molecules interacts with the electric field of linearly polarized light that angularly accelerates over the time of the optical pulse. This process drives molecules into high angular momentum states that are oriented with the optical field and have energies far from equilibrium. High resolution transient IR spectroscopy reveals the dynamics of collisional energy transfer for these super excited rotors. The results of this study leads to a more fundamental understanding of energy balance in non-equilibrium environments and the physical and chemical properties of gases in a new regime of energy states. Results will be presented for several super rotor species including carbon monoxide, carbon dioxide, and acetylene. Polarization-dependent measurements reveal the extent to which the super rotors maintain spatial orientation of high angular momentum states.

Polarization characterization of PZT disks and of embedded PZT plates by thermal wave methods

International Nuclear Information System (INIS)

Eydam, Agnes; Suchaneck, Gunnar; Gerlach, Gerald; Esslinger, Sophia; Schönecker, Andreas; Neumeister, Peter

2014-01-01

In this work, the thermal wave method was applied to characterize PZT disks and embedded PZT plates with regard to the polarization magnitude and spatial homogeneity. The samples were exposed to periodic heating by means of a laser beam and the pyroelectric response was determined. Thermal relaxation times (single time constants or distributions of time constants) describe the heat losses of the PZT samples to the environment. The resulting pyroelectric current spectrum was fitted to the superposition of thermal relaxation processes. The pyroelectric coefficient gives insight in the polarization distribution. For PZT disks, the polarization distribution in the surface region showed a characteristic decrease towards the electrodes

FAINT LUMINESCENT RING OVER SATURN’S POLAR HEXAGON

Energy Technology Data Exchange (ETDEWEB)

Adriani, Alberto; D’Aversa, Emiliano; Oliva, Fabrizio; Filacchione, Gianrico [Institute of Space Astrophysics and Planetology of INAF, Via Fosso del Cavaliere 100, I-00133 Rome (Italy); Moriconi, Maria Luisa, E-mail: alberto.adriani@iaps.inaf.it [Institute of Atmospheric Sciences and Climate of CNR, Via Fosso del Cavaliere 100, I-00133 Rome (Italy)

2015-07-20

Springtime insolation is presently advancing across Saturn's north polar region. Early solar radiation scattered through the gaseous giant's atmosphere gives a unique opportunity to sound the atmospheric structure at its upper troposphere/lower stratosphere at high latitudes. Here, we report the detection of a tenuous bright structure in Saturn's northern polar cap corresponding to the hexagon equatorward boundary, observed by Cassini Visual and Infrared Mapping Spectrometer on 2013 June. The structure is spectrally characterized by an anomalously enhanced intensity in the 3610–3730 nm wavelength range and near 2500 nm, pertaining to relatively low opacity windows between strong methane absorption bands. Our first results suggest that a strong forward scattering by tropospheric clouds, higher in respect to the surrounding cloud deck, can be responsible for the enhanced intensity of the feature. This can be consistent with the atmospheric dynamics associated with the jet stream embedded in the polar hexagon. Further investigations at higher spectral resolution are needed to better assess the vertical distribution and microphysics of the clouds in this interesting region.

Polarized neutrons

International Nuclear Information System (INIS)

Williams, W.G.

1988-01-01

The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)

POLAR NETWORK INDEX AS A MAGNETIC PROXY FOR THE SOLAR CYCLE STUDIES

International Nuclear Information System (INIS)

Priyal, Muthu; Banerjee, Dipankar; Ravindra, B.; Singh, Jagdev; Karak, Bidya Binay; Muñoz-Jaramillo, Andrés; Choudhuri, Arnab Rai

2014-01-01

The Sun has a polar magnetic field which oscillates with the 11 yr sunspot cycle. This polar magnetic field is an important component of the dynamo process which operates in the solar convection zone and produces the sunspot cycle. We have direct systematic measurements of the Sun's polar magnetic field only from about the mid-1970s. There are, however, indirect proxies which give us information about this field at earlier times. The Ca-K spectroheliograms taken at the Kodaikanal Solar Observatory during 1904-2007 have now been digitized with 4k × 4k CCD and have higher resolution (∼0.86 arcsec) than the other available historical data sets. From these Ca-K spectroheliograms, we have developed a completely new proxy (polar network index, hereafter PNI) for the Sun's polar magnetic field. We calculate PNI from the digitized images using an automated algorithm and calibrate our measured PNI against the polar field as measured by the Wilcox Solar Observatory for the period 1976-1990. This calibration allows us to estimate the polar fields for the earlier period up to 1904. The dynamo calculations performed with this proxy as input data reproduce reasonably well the Sun's magnetic behavior for the past century

POLAR NETWORK INDEX AS A MAGNETIC PROXY FOR THE SOLAR CYCLE STUDIES

Energy Technology Data Exchange (ETDEWEB)

Priyal, Muthu; Banerjee, Dipankar; Ravindra, B.; Singh, Jagdev [Indian Institute of Astrophysics,Koramangala, Bengaluru 560034 (India); Karak, Bidya Binay [Nordita, KTH Royal Institute of Technology and Stockholm University (Sweden); Muñoz-Jaramillo, Andrés [Montana State University, Bozeman, MT 59717 (United States); Choudhuri, Arnab Rai, E-mail: mpriya@iiap.res.in, E-mail: dipu@iiap.res.in [Indian Institute of Science, Bangalore (India)

2014-09-20

The Sun has a polar magnetic field which oscillates with the 11 yr sunspot cycle. This polar magnetic field is an important component of the dynamo process which operates in the solar convection zone and produces the sunspot cycle. We have direct systematic measurements of the Sun's polar magnetic field only from about the mid-1970s. There are, however, indirect proxies which give us information about this field at earlier times. The Ca-K spectroheliograms taken at the Kodaikanal Solar Observatory during 1904-2007 have now been digitized with 4k × 4k CCD and have higher resolution (∼0.86 arcsec) than the other available historical data sets. From these Ca-K spectroheliograms, we have developed a completely new proxy (polar network index, hereafter PNI) for the Sun's polar magnetic field. We calculate PNI from the digitized images using an automated algorithm and calibrate our measured PNI against the polar field as measured by the Wilcox Solar Observatory for the period 1976-1990. This calibration allows us to estimate the polar fields for the earlier period up to 1904. The dynamo calculations performed with this proxy as input data reproduce reasonably well the Sun's magnetic behavior for the past century.

Effect of solvent polarity and temperature on the spectral and thermodynamic properties of exciplexes of 1-cyanonaphthalene with hexamethylbenzene in organic solvents

Energy Technology Data Exchange (ETDEWEB)

Asim, Sadia [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad (Pakistan); Mansha, Asim [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Department of Chemistry, Government College University, Faisalabad (Pakistan); Grampp, Günter, E-mail: grampp@tugraz.at [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Landgraf, Stephan [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Zahid, Muhammad [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremaryrgasse 9, A-8010 Graz (Austria); Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad (Pakistan); Bhatti, Ijaz Ahmad [Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad (Pakistan)

2014-09-15

Study of the effect of solvent polarity and temperature is done on the exciplex emission spectra of 1-cyanonaphthalene with hexamethylbenzene. Exciplex system is studied in the range of partially polar solvents and in solvent mixture of propyl acetate and butyronitrile. The unique feature of this solvent mixture is that only the solvent polarity changes (6.0≤ε{sub s}≤24.7) with the change in the mole fraction of solvents whereas the solvent viscosity and refractive index remains unaffected. Thermodynamic properties are calculated according to the models developed by Weller and Kuzmin. Fluorescence lifetimes for both the fluorophore as well as the exciplex are evaluated in all used solvents. Exciplex energetics as a function of solvent polarity and temperature are also discussed. Kuzmin model of self-consistent polarization is used for the explanation of the exciplex emission spectra. The effects of solvent polarity and temperature on energy of zero–zero transitions (hv{sub 0}{sup /}), Huang–Rhys factor (S), Gauss broadening of vibronic level (σ) and the dominant high-frequency vibration (hν{sub ν}) are investigated. The strong dependence of exciplex stability and energetics upon the solvent polarity and temperature are observed. Full charge transfer exciplexes were observed in solvents of all polarities and stronger exciplex with large emission intensities were found in solvents of low polarities but with the increase in solvent polarity the exciplex becomes weak and they dissociate fastly into radical ion pairs. The kinetic model of Kuzmin was observed to reduce into the Weller kinetic model for this exciplex system with ∆G{sub ET} = −0.22 eV and the spectral shift, h∆ν>0.2 eV. - Highlights: • Exciplex formed as a result of mixing of charge transfer and locally excited states. • Effect of solvents polarity and temperature on the exciplex stability and thermodynamics. • Solvent polarity will decide the formation of contact radical ion pair

Boiling heat transfer modern developments and advances

CERN Document Server

Lahey, Jr, RT

2013-01-01

This volume covers the modern developments in boiling heat transfer and two-phase flow, and is intended to provide industrial, government and academic researchers with state-of-the-art research findings in the area of multiphase flow and heat transfer technology. Special attention is given to technology transfer, indicating how recent significant results may be used for practical applications. The chapters give detailed technical material that will be useful to engineers and scientists who work in the field of multiphase flow and heat transfer. The authors of all chapters are members of the

Multiangular hyperspectral investigation of polarized light in case 2 waters

Science.gov (United States)

Tonizzo, A.; Zhou, J.; Gilerson, A.; Chowdhary, J.; Gross, B.; Moshary, F.; Ahmed, S.

2009-09-01

The focus of this work is on the dependence of in situ hyperspectral and multiangular polarized data on the size distribution and refractive index of the suspended particles. Underwater polarization measurements were obtained using a polarimeter developed at the Optical Remote Sensing Laboratory of the City College of New York, NY. The degree of polarization (DOP) of the underwater light field in coastal environments was measured and the water-leaving polarized radiance was derived. In-water optical properties were also measured with an ac-9 (WET Labs). Absorption and attenuation spectra are then used to derive information on the dissolved and suspend components in the water medium which are used in a vector radiative transfer code which provides the upwelling radiance. The model was run for various values of the refractive index of mineral particles until the modeled DOP matched the measured one. The relationship between the intensity of the maximum of the DOP and both the refractive index of the mineral particles and the shapes of their size distributions is analyzed in detail.

Realization of a broad band neutron spin filter with compressed, polarized 3He gas

International Nuclear Information System (INIS)

Surkau, R.; Otten, E.W.; Steiner, M.; Tasset, F.; Trautmann, N.

1997-01-01

The strongly spin dependent absorption of neutrons in nuclear spin polarized 3 -2pt vector He opens the possibility to polarize beams of thermal and epithermal neutrons. An effective 3 He neutron spin filter (NSF) requires high 3 He nuclear polarization as well as a filter thickness corresponding to a gas amount of the order of 1 bar l. We realized such a filter using direct optical pumping of metastable 3 He * atoms in a 3 He plasma at 1 mbar. Metastable exchange scattering transfers the angular momentum to the whole ensemble of 3 He atoms. At present 3 x 10 18 3 He-atoms/s are polarized up to 64%. Subsequent polarization preserving compression by a two stage compressor system enables to prepare NSF cells of about 300 cm 3 volume with 3 bar of polarized 3 He within 2 h. 3 He polarizations up to 53% were measured in a cell with a filter length of about 15 cm. By this cell a thermal neutron beam from the Mainz TRIGA reactor was polarized. A wavelength selective polarization analysis by means of Bragg scattering revealed a neutron polarization of 84% at a total transmission of 12% for a neutron wavelength of 1 A. (orig.)

Polarized recombination of acoustically transported carriers in GaAs nanowires

Science.gov (United States)

Möller, Michael; Hernández-Mínguez, Alberto; Breuer, Steffen; Pfüller, Carsten; Brandt, Oliver; de Lima, Mauricio M.; Cantarero, Andrés; Geelhaar, Lutz; Riechert, Henning; Santos, Paulo V.

2012-05-01

The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited electrons and holes in GaAs nanowires deposited on a SAW delay line on a LiNbO3 crystal. The carriers generated in the nanowire by a focused light spot are acoustically transferred to a second location where they recombine. We show that the recombination of the transported carriers occurs in a zinc blende section on top of the predominant wurtzite nanowire. This allows contactless control of the linear polarized emission by SAWs which is governed by the crystal structure. Additional polarization-resolved photoluminescence measurements were performed to investigate spin conservation during transport.

Induced polarization of Λ (1116) in kaon electroproduction

Science.gov (United States)

Gabrielyan, M.; Raue, B. A.; Carman, D. S.; Park, K.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Baturin, V.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Cao, T.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Forest, T. A.; Garillon, B.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hattawy, M.; Hicks, K.; Ho, D.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, W.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Levine, W. I.; Livingston, K.; MacGregor, I. J. D.; Mayer, M.; McKinnon, B.; Meyer, C. A.; Mestayer, M. D.; Mirazita, M.; Mokeev, V.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Pappalardo, L. L.; Paremuzyan, R.; Pasyuk, E.; Peng, P.; Phelps, W.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Rimal, D.; Ripani, M.; Rizzo, A.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Simonyan, A.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Tang, W.; Ungaro, M.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.; CLAS Collaboration

2014-09-01

We have measured. the induced polarization of the Λ(1116) in the reaction ep →e'K+Λ, detecting the scattered e' and K+ in the final state along with the proton from the decay Λ →pπ-. The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy W (1.6≤W≤2.7 GeV) and covered the full range of the kaon production angle at an average momentum transfer Q2=1.90GeV2. In this experiment a 5.50-GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the W and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially Q2 independent in our kinematic domain, suggesting that somewhere below the Q2 covered here there must be a strong Q2 dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved s-channel resonances.

Recursive polarization of nuclear spins in diamond at arbitrary magnetic fields

International Nuclear Information System (INIS)

Pagliero, Daniela; Laraoui, Abdelghani; Henshaw, Jacob D.; Meriles, Carlos A.

2014-01-01

We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave, and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR

Polarization singularities of optical fields caused by structural dislocations in crystals

International Nuclear Information System (INIS)

Savaryn, V; Vasylkiv, Yu; Krupych, O; Skab, I; Vlokh, R

2013-01-01

We analyze polarization singularities of optical beams that propagate through crystals possessing structural dislocations. We show that screw dislocations of crystalline structure can lead to the appearance of purely screw-type dislocations of light wavefronts. This can happen only in crystals that belong to trigonal and cubic systems. These polarization singularities will give rise to optical vortices with the topological charge equal to ±1, whenever a crystal sample is placed between crossed circular polarizers. We have also found that edge dislocations present in the cubic and trigonal crystals, with the Burgers vector perpendicular to the three-fold symmetry axes, can impose mixed screw-edge dislocations in the wavefronts of optical beams and generate singly charged optical vortices. The results of our analysis can be applied for detecting and identifying dislocations of different types available in crystals. (paper)

Space Radiation Measurement on the Polar Route onboard the Korean Commercial Flights

Directory of Open Access Journals (Sweden)

Junga Hwang

2010-03-01

Full Text Available This study was performed by the policy research project of Ministry of Land, Transport and Maritime Affairs, which title is “Developing safety standards and management of space radiation on the polar route”. In this research, total six experiments were performed using Korean commercial flights (B747. Three of those are on the polar route and the other three are on the north pacific route. Space radiation exposure measured on the polar route is the average 84.7 uSv. The simulation result using CARI-6M program gives 84.9 uSv, which is very similar to measured value. For the departure flight using the north pacific route, the measured space radiation is the average 74.4 uSv. It seems that is not so different to use the polar route or not for the return flight because the higher latitude effect causing the increase of space radiation is compensated by the shortened flight time effect causing decreasing space radiation exposure.

Effects of multiple scattering and atmospheric aerosol on the polarization of the twilight sky

International Nuclear Information System (INIS)

Ugolnikov, Oleg S.; Postylyakov, Oleg V.; Maslov, Igor A.

2004-01-01

The paper presents a review of a number of wide-angle polarization CCD-measurements of the twilight sky in V and R color bands with effective wavelengths 550 and 700nm. The basic factors affecting (usually decreasing) the polarization of the twilight sky are the atmospheric aerosol scattering and multiple scattering. These effects were distinguished from each other, and a method of multiple-scattering separation is discussed. The results are compared with the data of numerical simulation of radiative transfer in the atmosphere for different aerosol models. The whole twilight period is divided into different stages with different mechanisms forming the twilight-sky polarization properties

Workshop on polarized neutron filters and polarized pulsed neutron experiments

International Nuclear Information System (INIS)

Itoh, Shinichi

2004-07-01

The workshop was held in KEK by thirty-three participants on April 26, 2004. The polarized neutron filter method was only discussed. It consists of three parts; the first part was discussed on the polarized neutron methods, the second part on the polarized neutron experiments and the third on the pulse neutron spectrometer and polarized neutron experiments. The six papers were presented such as the polarized 3 He neutron spin filter, neutron polarization by proton polarized filter, soft master and neutron scattering, polarized neutron in solid physics, polarization experiments by chopper spectroscope and neutron polarization system in superHRPD. (S.Y.)

Electrochemical behavior of uranyl in anhydrous polar organic media

Energy Technology Data Exchange (ETDEWEB)

Burn, Adam G.; Nash, Kenneth L. [Washington State Univ., Pullmann, WA (United States). Dept. of Chemistry

2017-09-01

Weak complexes between pentavalent and hexavalent actinyl cations have been reported to exist in acidic, non-complexing high ionic strength aqueous media. Such ''cation-cation complexes'' were first identified in the context of actinide-actinide redox reactions in acidic aqueous media relevant to solvent extraction-based separation systems, hence their characterization is of potential interest for advanced nuclear fuel reprocessing. This chemistry could be relevant to efforts to develop advanced actinide separations based on the upper oxidation states of americium, which are of current interest. In the present study, the chemical behavior of pentavalent uranyl was examined in non-aqueous, aprotic polar organic solvents (propylene carbonate and acetonitrile) to determine whether UO{sub 2}{sup +} cations generated at the reducing working electrode surface would interact with the UO{sub 2}{sup 2+} cations in the bulk phase to form cation-cation complexes in such media. In magnesium perchlorate media, the electrolyte adsorbed onto the working electrode surface and interfered with the uranyl reduction/diffusion process through an ECE (electron transfer/chemical reaction/electron transfer) mechanism. In parallel studies of uranyl redox behavior in tetrabutylammonium hexafluorophosphate solutions, an EC (electron transfer/chemical reaction) mechanism was observed in the cyclic voltammograms. Ultimately, no conclusive electrochemical evidence demonstrated uranyl cation-cation interactions in the non-aqueous, aprotic polar organic solvent solutions, though the results reported do not completely rule out the presence of UO{sub 2}{sup +}.UO{sub 2}{sup 2+} complexes.

Second-harmonic generation in shear wave beams with different polarizations

Science.gov (United States)

Spratt, Kyle S.; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hamilton, Mark F.

2015-10-01

A coupled pair of nonlinear parabolic equations was derived by Zabolotskaya [1] that model the transverse components of the particle motion in a collimated shear wave beam propagating in an isotropic elastic solid. Like the KZK equation, the parabolic equation for shear wave beams accounts consistently for the leading order effects of diffraction, viscosity and nonlinearity. The nonlinearity includes a cubic nonlinear term that is equivalent to that present in plane shear waves, as well as a quadratic nonlinear term that is unique to diffracting beams. The work by Wochner et al. [2] considered shear wave beams with translational polarizations (linear, circular and elliptical), wherein second-order nonlinear effects vanish and the leading order nonlinear effect is third-harmonic generation by the cubic nonlinearity. The purpose of the current work is to investigate the quadratic nonlinear term present in the parabolic equation for shear wave beams by considering second-harmonic generation in Gaussian beams as a second-order nonlinear effect using standard perturbation theory. In order for second-order nonlinear effects to be present, a broader class of source polarizations must be considered that includes not only the familiar translational polarizations, but also polarizations accounting for stretching, shearing and rotation of the source plane. It is found that the polarization of the second harmonic generated by the quadratic nonlinearity is not necessarily the same as the polarization of the source-frequency beam, and we are able to derive a general analytic solution for second-harmonic generation from a Gaussian source condition that gives explicitly the relationship between the polarization of the source-frequency beam and the polarization of the second harmonic.

Second-harmonic generation in shear wave beams with different polarizations

Energy Technology Data Exchange (ETDEWEB)

Spratt, Kyle S., E-mail: sprattkyle@gmail.com; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hamilton, Mark F. [Applied Research Laboratories, The University of Texas at Austin, P. O. Box 8029, Austin, Texas 78713–8029, US (United States)

2015-10-28

A coupled pair of nonlinear parabolic equations was derived by Zabolotskaya [1] that model the transverse components of the particle motion in a collimated shear wave beam propagating in an isotropic elastic solid. Like the KZK equation, the parabolic equation for shear wave beams accounts consistently for the leading order effects of diffraction, viscosity and nonlinearity. The nonlinearity includes a cubic nonlinear term that is equivalent to that present in plane shear waves, as well as a quadratic nonlinear term that is unique to diffracting beams. The work by Wochner et al. [2] considered shear wave beams with translational polarizations (linear, circular and elliptical), wherein second-order nonlinear effects vanish and the leading order nonlinear effect is third-harmonic generation by the cubic nonlinearity. The purpose of the current work is to investigate the quadratic nonlinear term present in the parabolic equation for shear wave beams by considering second-harmonic generation in Gaussian beams as a second-order nonlinear effect using standard perturbation theory. In order for second-order nonlinear effects to be present, a broader class of source polarizations must be considered that includes not only the familiar translational polarizations, but also polarizations accounting for stretching, shearing and rotation of the source plane. It is found that the polarization of the second harmonic generated by the quadratic nonlinearity is not necessarily the same as the polarization of the source-frequency beam, and we are able to derive a general analytic solution for second-harmonic generation from a Gaussian source condition that gives explicitly the relationship between the polarization of the source-frequency beam and the polarization of the second harmonic.

Second-harmonic generation in shear wave beams with different polarizations

International Nuclear Information System (INIS)

Spratt, Kyle S.; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hamilton, Mark F.

2015-01-01

A coupled pair of nonlinear parabolic equations was derived by Zabolotskaya [1] that model the transverse components of the particle motion in a collimated shear wave beam propagating in an isotropic elastic solid. Like the KZK equation, the parabolic equation for shear wave beams accounts consistently for the leading order effects of diffraction, viscosity and nonlinearity. The nonlinearity includes a cubic nonlinear term that is equivalent to that present in plane shear waves, as well as a quadratic nonlinear term that is unique to diffracting beams. The work by Wochner et al. [2] considered shear wave beams with translational polarizations (linear, circular and elliptical), wherein second-order nonlinear effects vanish and the leading order nonlinear effect is third-harmonic generation by the cubic nonlinearity. The purpose of the current work is to investigate the quadratic nonlinear term present in the parabolic equation for shear wave beams by considering second-harmonic generation in Gaussian beams as a second-order nonlinear effect using standard perturbation theory. In order for second-order nonlinear effects to be present, a broader class of source polarizations must be considered that includes not only the familiar translational polarizations, but also polarizations accounting for stretching, shearing and rotation of the source plane. It is found that the polarization of the second harmonic generated by the quadratic nonlinearity is not necessarily the same as the polarization of the source-frequency beam, and we are able to derive a general analytic solution for second-harmonic generation from a Gaussian source condition that gives explicitly the relationship between the polarization of the source-frequency beam and the polarization of the second harmonic

Investigation of. epsilon. sub 1 and the sup 3 P sub J phase shifts in the n-p system by the measurement of polarization transfer coefficients in p-d elastic scattering

Energy Technology Data Exchange (ETDEWEB)

Clajus, M.; Egun, P.M.; Grueebler, W.; Hautle, P. (Eidgenoessische Technische Hochschule, Zurich (Switzerland). Inst. fuer Mittelenergiephysik); Kretschmer, W.; Rauscher, A.; Schuster, W.; Weidmann, R.; Haller, M. (Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.). Physikalisches Inst.); Bruno, M.; Cannata, F.; D' Agostino, M. (Istituto Nazionale di Fisica Nucleare, Bologna (Italy) Bologna Univ. (Italy). Dipt. di Fisica); Slaus, I. (Institut Rudjer Boskovic, Zagreb (Yugoslavia)); Schmelzbach, P.A. (Paul Scherrer Inst., Villigen (Switzerland)); Vuaridel, B. (Michigan Univ., Ann Arbor (USA)); Sperisen, F. (Indiana Univ., Bloomington (USA). Cyclotron Facility); Witala, H.; Cornelius, T.; Gloeckle, W. (Bochum Univ. (Germany, F.R.))

1990-02-01

The {sup 3}S{sub 1}-{sup 3}D{sub 1} mixing parameter {epsilon}{sub 1} and the {sup 3}P{sub J} phase shifts in the N-N system at low energy are investigated in the three nucleon system. The sensitivity of polarization transfer coefficients in p-d elastic scattering is determined by rigorous Faddeev calculations using Paris and Bonn potentials. The experimental results of K{sub y}sup(y') favours the tensor force component of the Bonn A potential. (orig.).

Transfer matrix approach for the Kerr and Faraday rotation in layered nanostructures.

Science.gov (United States)

Széchenyi, Gábor; Vigh, Máté; Kormányos, Andor; Cserti, József

2016-09-21

To study the optical rotation of the polarization of light incident on multilayer systems consisting of atomically thin conductors and dielectric multilayers we present a general method based on transfer matrices. The transfer matrix of the atomically thin conducting layer is obtained using the Maxwell equations. We derive expressions for the Kerr (Faraday) rotation angle and for the ellipticity of the reflected (transmitted) light as a function of the incident angle and polarization of the light. The method is demonstrated by calculating the Kerr (Faraday) angle for bilayer graphene in the quantum anomalous Hall state placed on the top of dielectric multilayers. The optical conductivity of the bilayer graphene is calculated in the framework of a four-band model.

Heat transfer with geometric shape of micro-fin tubes (I) - Condensing heat transfer

Energy Technology Data Exchange (ETDEWEB)

Kwak, K M; Chang, J S; Bai, C H; Chung, M [Yeungnam University, Kyungsan (Korea)

1999-11-01

To examine the enhancement mechanism of condensing heat transfer through microfin tube, the condensation experiments with refrigerant HCFC 22 are performed using 4 and 6 kinds of microfin tubes with outer diameter of 9.52 mm and 7.0 mm, respectively. Used microfin tubes have different shape and number of fins with each other. The main heat transfer enhancement mechanism is known to be the enlargement of heat transfer area and turbulence promotion. Together with these main factors, we can find other enhancement factors by the experimental data, which are the overflow of the refrigerant over the microfin and microfin arrangement. The overflow of the refrigerant over the microfin can be analyzed by the geometric shape of the microfin. microfin tubes having a shape which can give much overflow over the microfin show large condensing heat transfer coefficients. The effect of microfin arrangement is related to the heat transfer resistance of liquid film of refrigerant. The condensing heat transfer coefficients are high for the microfin tube with even distribution of liquid film. 17 refs., 14 figs., 3 tabs.

Spectral element method for vector radiative transfer equation

International Nuclear Information System (INIS)

Zhao, J.M.; Liu, L.H.; Hsu, P.-F.; Tan, J.Y.

2010-01-01

A spectral element method (SEM) is developed to solve polarized radiative transfer in multidimensional participating medium. The angular discretization is based on the discrete-ordinates approach, and the spatial discretization is conducted by spectral element approach. Chebyshev polynomial is used to build basis function on each element. Four various test problems are taken as examples to verify the performance of the SEM. The effectiveness of the SEM is demonstrated. The h and the p convergence characteristics of the SEM are studied. The convergence rate of p-refinement follows the exponential decay trend and is superior to that of h-refinement. The accuracy and efficiency of the higher order approximation in the SEM is well demonstrated for the solution of the VRTE. The predicted angular distribution of brightness temperature and Stokes vector by the SEM agree very well with the benchmark solutions in references. Numerical results show that the SEM is accurate, flexible and effective to solve multidimensional polarized radiative transfer problems.

Give Me Strength.

Institute of Scientific and Technical Information of China (English)

维拉

1996-01-01

Mort had an absolutely terrible day at the office.Everythingthat could go wrong did go wrong.As he walked home he could beheard muttering strange words to himself:“Oh,give me strength,give me strength.”Mort isn’t asking for the kind of strength thatbuilds strong muscles:he’s asking for the courage or ability to

Ideal heat transfer conditions for tubular solar receivers with different design constraints

Science.gov (United States)

Kim, Jin-Soo; Potter, Daniel; Gardner, Wilson; Too, Yen Chean Soo; Padilla, Ricardo Vasquez

2017-06-01

The optimum heat transfer condition for a tubular type solar receiver was investigated for various receiver pipe size, heat transfer fluid, and design requirement and constraint(s). Heat transfer of a single plain receiver pipe exposed to concentrated solar energy was modelled along the flow path of the heat transfer fluid. Three different working fluids, molten salt, sodium, and supercritical carbon dioxide (sCO2) were considered in the case studies with different design conditions. The optimized ideal heat transfer condition was identified through fast iterative heat transfer calculations solving for all relevant radiation, conduction and convection heat transfers throughout the entire discretized tubular receiver. The ideal condition giving the best performance was obtained by finding the highest acceptable solar energy flux optimally distributed to meet different constraint(s), such as maximum allowable material temperature of receiver, maximum allowable film temperature of heat transfer fluid, and maximum allowable stress of receiver pipe material. The level of fluid side turbulence (represented by pressure drop in this study) was also optimized to give the highest net power production. As the outcome of the study gives information on the most ideal heat transfer condition, it can be used as a useful guideline for optimal design of a real receiver and solar field in a combined manner. The ideal heat transfer condition is especially important for high temperature tubular receivers (e.g. for supplying heat to high efficiency Brayton cycle turbines) where the system design and performance is tightly constrained by the receiver pipe material strength.

IOCCG Report Number 16, 2015 Ocean Colour Remote Sensing in Polar Seas . Chapter 2; The Polar Environment: Sun, Clouds, and Ice

Science.gov (United States)

Comiso, Josefino C.; Perovich, Don; Stamnes, Knut; Stuart, Venetia (Editor)

2015-01-01

The polar regions are places of extremes. There are months when the regions are enveloped in unending darkness, and months when they are in continuous daylight. During the daylight months the sun is low on the horizon and often obscured by clouds. In the dark winter months temperatures are brutally cold, and high winds and blowing snow are common. Even in summer, temperatures seldom rise above 0degC. The cold winter temperatures cause the ocean to freeze, forming sea ice. This sea ice cover acts as a barrier limiting the transfer of heat, moisture, and momentum between the atmosphere and the ocean. It also greatly complicates the optical signature of the surface. Taken together, these factors make the polar regions a highly challenging environment for optical remote sensing of the ocean.

High-precision broad-band linear polarimetry of early-type binaries. II. Variable, phase-locked polarization in triple Algol-type system λ Tauri

Science.gov (United States)

Berdyugin, A.; Piirola, V.; Sakanoi, T.; Kagitani, M.; Yoneda, M.

2018-03-01

Aim. To study the binary geometry of the classic Algol-type triple system λ Tau, we have searched for polarization variations over the orbital cycle of the inner semi-detached binary, arising from light scattering in the circumstellar material formed from ongoing mass transfer. Phase-locked polarization curves provide an independent estimate for the inclination i, orientation Ω, and the direction of the rotation for the inner orbit. Methods: Linear polarization measurements of λ Tau in the B, V , and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained on the 60 cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and Tohoku 60 cm (Haleakala, Hawaii, USA) remotely controlled telescopes over 69 observing nights. Analytic and numerical modelling codes are used to interpret the data. Results: Optical polarimetry revealed small intrinsic polarization in λ Tau with 0.05% peak-to-peak variation over the orbital period of 3.95 d. The variability pattern is typical for binary systems showing strong second harmonic of the orbital period. We apply a standard analytical method and our own light scattering models to derive parameters of the inner binary orbit from the fit to the observed variability of the normalized Stokes parameters. From the analytical method, the average for three passband values of orbit inclination i = 76° + 1°/-2° and orientation Ω = 15°(195°) ± 2° are obtained. Scattering models give similar inclination values i = 72-76° and orbit orientation ranging from Ω = 16°(196°) to Ω = 19°(199°), depending on the geometry of the scattering cloud. The rotation of the inner system, as seen on the plane of the sky, is clockwise. We have found that with the scattering model the best fit is obtained for the scattering cloud located between the primary and the secondary, near the inner Lagrangian point or along the Roche lobe surface of the secondary facing the primary. The inclination i

Energy technology transfer to developing countries

International Nuclear Information System (INIS)

Goldemberg, J.

1991-01-01

This paper gives some examples of how technology transfer can successfully be given to third world countries to allow them to benefit in their quest for economic growth and better standards of living through reduced energy consumption and environmental pollution. It also suggests methods by which obstacles such as high investment costs, lack of information, market demand, etc., can be overcome in order to motivate technological transfer by industrialized countries

Intramolecular, Exciplex-Mediated, Proton-Coupled, Charge-Transfer Processes in N,N-Dimethyl-3-(1-pyrenyl)propan-1-ammonium Cations: Influence of Anion, Solvent Polarity, and Temperature.

Science.gov (United States)

Safko, Trevor M; Faleiros, Marcelo M; Atvars, Teresa D Z; Weiss, Richard G

2016-06-16

An intramolecular exciplex-mediated, proton-coupled, charge-transfer (PCCT) process has been investigated for a series of N,N-dimethyl-3-(1-pyrenyl)propan-1-ammonium cations with different anions (PyS) in solvents of low to intermediate polarity over a wide temperature range. Solvent mediates both the equilibrium between conformations of the cation that place the pyrenyl and ammonium groups in proximity (conformation C) or far from each other (conformation O) and the ability of the ammonium group to transfer a proton adiabatically in the PyS excited singlet state. Thus, exciplex emission, concurrent with the PCCT process, was observed only in hydrogen-bond accepting solvents of relatively low polarity (tetrahydrofuran, ethyl acetate, and 1,4-dioxane) and not in dichloromethane. From the exciplex emission and other spectroscopic and thermodynamic data, the acidity of the ammonium group in conformation C of the excited singlet state of PyS (pKa*) has been estimated to be ca. -3.4 in tetrahydrofuran. The ratios between the intensities of emission from the exciplex and the locally excited state (IEx/ILE) appear to be much more dependent on the nature of the anion than are the rates of exciplex formation and decay, although the excited state data do not provide a quantitative measure of the anion effect on the C-O equilibrium. The activation energies associated with exciplex formation in THF are calculated to be 0.08 to 0.15 eV lower than for the neutral amine, N,N-dimethyl-3-(1-pyrenyl)propan-1-amine. Decay of the exciplexes formed from the deprotonation of PyS is hypothesized to occur through charge-recombination processes. To our knowledge, this is the first example in which photoacidity and intramolecular exciplex formation (i.e., a PCCT reaction) are coupled.

Independent control of the vortex chirality and polarity in a pair of magnetic nanodots

Energy Technology Data Exchange (ETDEWEB)

Li, Junqin; Wang, Yong, E-mail: wangyong@sinap.ac.cn; Cao, Jiefeng; Meng, Xiangyu; Zhu, Fangyuan; Wu, Yanqing; Tai, Renzhong

2017-08-01

Independent control of the vortex chirality and polarity is realized by changing the in-plane magnetic field direction in nanodot pair through Object Oriented Micromagnetic Framework (OOMMF) simulation. The two magnetic circles are close to each other and have magnetic interaction. The two circles always have the same polarity and opposite chirality at every remanent state. There are totally four predictable magnetic states in the nanodot pair which can be obtained in the remanent state relaxed from the saturation state along all possible directions. An explanation on the formation of vortex states is given by vortex dynamics. The vortex states are stable in large out-of-plane magnetic field which is in a direction opposite to the vortex polarity. The geometry of the nanodot pair gives a way to easily realize a vortex state with specific polarity and chirality.

On the spectrum and polarization of magnetar flare emission

Science.gov (United States)

Taverna, R.; Turolla, R.

2017-08-01

Bursts and flares are among the distinctive observational manifestations of magnetars, isolated neutron stars endowed with an ultrastrong magnetic field (B ≈ 1014-1015 G). It is believed that these events arise in a hot electron-positron plasma that remains trapped within the closed magnetic field lines. We developed a simple radiative transfer model to simulate magnetar flare emission in the case of a steady trapped fireball. After dividing the fireball surface in a number of plane-parallel slabs, the local spectral and polarization properties are obtained integrating the radiative transfer equations for the two normal modes. We assume that magnetic Thomson scattering is the dominant source of opacity, and neglect contributions from second-order radiative processes, although double-Compton scattering is accounted for in establishing local thermal equilibrium in the fireball atmospheric layers. The observed spectral and polarization properties as measured by a distant observer are obtained by summing the contributions from the patches that are visible for a given viewing geometry by means of a ray-tracing code. The spectra we obtained in the 1-100 keV energy range are thermal and can be described in terms of the superposition of two blackbodies. The blackbody temperature and the emitting area ratio are in broad agreement with the available observations. The predicted linear polarization degree is, in general, greater than 80 per cent over the entire energy range and should be easily detectable by new-generation X-ray polarimeters, such as IXPE, XIPE and eXTP.

Plasmonic energy transfer in periodically doped graphene

International Nuclear Information System (INIS)

Silveiro, I; Manjavacas, A; Thongrattanasiri, S; García de Abajo, F J

2013-01-01

We predict unprecedentedly large values of the energy-transfer rate between an optical emitter and a layer of periodically doped graphene. The transfer exhibits divergences at photon frequencies corresponding to the Van Hove singularities of the plasmonic band structure of the graphene. In particular, we find flat bands associated with regions of vanishing doping charge, which appear in graphene when it is patterned through gates of spatially alternating signs, giving rise to intense transfer rate singularities. Graphene is thus shown to provide a unique platform for fast control of optical energy transfer via fast electrostatic inhomogeneous doping. (paper)

Pollen irradiation and possible gene transfer in Nicotiana species

DEFF Research Database (Denmark)

Engvild, Kjeld Christensen

1985-01-01

, and Petunia parodii with irradiated pollen from N. alata and Petunia hybrida showed no evidence of gene transfer, nor did experiments with irradiated mentor pollen. This indicates that gene transfer with irradiated pollen between non-crossing species or between species giving sterile hybrids is probably...

A STUDY OF RADIO POLARIZATION IN PROTOSTELLAR JETS

Energy Technology Data Exchange (ETDEWEB)

Cécere, Mariana [Instituto de Astronomía Teórica y Experimental, Universidad Nacional de Córdoba, X5000BGR, Córdoba (Argentina); Velázquez, Pablo F.; De Colle, Fabio; Esquivel, Alejandro [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, CP: 04510, D.F., México (Mexico); Araudo, Anabella T. [University of Oxford, Astrophysics, Keble Road, Oxford OX1 3RH (United Kingdom); Carrasco-González, Carlos; Rodríguez, Luis F. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 3-72, 58090, Morelia, Michoacán, México (Mexico)

2016-01-10

Synchrotron radiation is commonly observed in connection with shocks of different velocities, ranging from relativistic shocks associated with active galactic nuclei, gamma-ray bursts, or microquasars, to weakly or non-relativistic flows such as those observed in supernova remnants. Recent observations of synchrotron emission in protostellar jets are important not only because they extend the range over which the acceleration process works, but also because they allow us to determine the jet and/or interstellar magnetic field structure, thus giving insights into the jet ejection and collimation mechanisms. In this paper, we compute for the first time polarized (synchrotron) and non-polarized (thermal X-ray) synthetic emission maps from axisymmetrical simulations of magnetized protostellar jets. We consider models with different jet velocities and variability, as well as a toroidal or helical magnetic field. Our simulations show that variable, low-density jets with velocities of ∼1000 km s{sup −1} and ∼10 times lighter than the environment can produce internal knots with significant synchrotron emission and thermal X-rays in the shocked region of the leading bow shock moving in a dense medium. While models with a purely toroidal magnetic field show a very large degree of polarization, models with a helical magnetic field show lower values and a decrease of the degree of polarization, in agreement with observations of protostellar jets.

A Polarizable and Transferable PHAST CO 2 Potential for Materials Simulation

KAUST Repository

Mullen, Ashley L.; Pham, Tony; Forrest, Katherine A.; Cioce, Christian R.; McLaughlin, Keith; Space, Brian

2013-01-01

Reliable PHAST (Potentials with High Accuracy Speed and Transferability) intermolecular potential energy functions for CO2 have been developed from first principles for use in heterogeneous systems, including one with explicit polarization

Photonic engineering of highly linearly polarized quantum dot emission at telecommunication wavelengths

Science.gov (United States)

Mrowiński, P.; Emmerling, M.; Schneider, C.; Reithmaier, J. P.; Misiewicz, J.; Höfling, S.; Sek, G.

2018-04-01

In this work, we discuss a method to control the polarization anisotropy of spontaneous emission from neutral excitons confined in quantum-dot-like nanostructures, namely single epitaxial InAs quantum dashes emitting at telecom wavelengths. The nanostructures are embedded inside lithographically defined, in-plane asymmetric photonic mesa structures, which generate polarization-dependent photonic confinement. First, we study the influence of the photonic confinement on the polarization anisotropy of the emission by photoluminescence spectroscopy, and we find evidence of different contributions to a degree of linear polarization (DOLP), i.e., from the quantum dash and the photonic mesa, in total giving rise to DOLP =0.85 . Then, we perform finite-difference time-domain simulations of photonic confinement, and we calculate the DOLP in a dipole approximation showing well-matched results for the established model. Furthermore, by using numerical calculations, we demonstrate several types of photonic confinements where highly linearly polarized emission with DOLP of about 0.9 is possible by controlling the position of a quantum emitter inside the photonic structure. Then, we elaborate on anisotropic quantum emitters allowing for exceeding DOLP =0.95 in an optimized case, and we discuss the ways towards efficient linearly polarized single photon source at telecom bands.

Polarization, alignment, and orientation in atomic collisions

CERN Document Server

Andersen, Nils

2017-01-01

This book covers polarization, alignment, and orientation effects in atomic collisions induced by electron, heavy particle, or photon impact. The first part of the book presents introductory chapters on light and particle polarization, experimental and computational methods, and the density matrix and state multipole formalism. Examples and exercises are included. The second part of the book deals with case studies of electron impact and heavy particle excitation, electron transfer, impact ionization, and autoionization. A separate chapter on photo-induced processes by new-generation light sources has been added. The last chapter discusses related topics and applications. Part III includes examples of charge clouds and introductory summaries of selected seminal papers of tutorial value from the early history of the field (1925 – 1975). The book is a significant update to the previous (first) edition, particularly in experimental and computational methods, the inclusion of key results obtained during the pas...

Dispersion properties of transverse waves in electrically polarized BECs

International Nuclear Information System (INIS)

Andreev, Pavel A; Kuz'menkov, L S

2014-01-01

Further development of the method of quantum hydrodynamics in applications for Bose–Einstein condensates (BECs) is presented. To consider the evolution of polarization direction along with particle movement, we have developed a corresponding set of quantum hydrodynamic equations. It includes equations of the polarization evolution and the polarization-current evolution along with the continuity equation and the Euler equation (the momentum-balance equation). Dispersion properties of the transverse waves, including the electromagnetic waves propagating through the BECs, are considered. To this end, we consider a full set of the Maxwell equations for the description of electromagnetic field dynamics. This approximation gives us the possibility of considering the electromagnetic waves along with the matter waves. We find a splitting of the electromagnetic-wave dispersion on two branches. As a result, we have four solutions, two for the electromagnetic waves and two for the matter waves; the last two are the concentration-polarization waves appearing as a generalization of the Bogoliubov mode. We also find that if the matter wave propagates perpendicular to the external electric field then the dipolar contribution does not disappear (as it follows from our generalization of the Bogoliubov spectrum). A small dipolar frequency shift exists in this case due to the transverse electric field of perturbation. (paper)

A new approach to radiative transfer theory using Jones's vectors. I

International Nuclear Information System (INIS)

Fymat, A.L.; Vasudevan, R.

1975-01-01

Radiative transfer of partially polarized radiation in an anisotropically scattering, inhomogeneous atmosphere containing arbitrary polydispersion of particles is described using Jones's amplitude vectors and matrices. This novel approach exploits the close analogy between the quantum mechanical states of spin 1/2 systems and the polarization states of electromagnetic radiation described by Jones's vector, and draws on the methodology of such spin 1/2 systems. The complete equivalence between the transport equation for Jones's vectors and the classical radiative transfer equation for Stokes's intensity vectors is demonstrated in two independent ways after deriving the transport equations for the polarization coherency matrices and for the quaternions corresponding to the Jones's vectors. A compact operator formulation of the theory is provided, and used to derive the necessary equations for both a local and a global description of the transport of Jones's vectors. Lastly, the integro-differential equations for the amplitude reflection and transmission matrices are derived, and related to the usual corresponding equations. The present formulation is the most succinct and the most convenient one for both theoretical and experimental studies. It yields a simpler analysis than the classical formulation since it reduces by a factor of two the dimensionality of transfer problems. It preserves information on phases, and thus can be used directly across the entire electromagnetic spectrum without any further conversion into intensities. (Auth.)

Modeling spin selectivity in charge transfer across the DNA/Gold interface

Energy Technology Data Exchange (ETDEWEB)

Behnia, S., E-mail: s.behnia@sci.uut.ac.ir [Department of Physics, Urmia University of Technology, Urmia (Iran, Islamic Republic of); Fathizadeh, S. [Department of Physics, Urmia University of Technology, Urmia (Iran, Islamic Republic of); Akhshani, A. [Department of Physics, Urmia Branch, Islamic Azad University, Urmia (Iran, Islamic Republic of)

2016-09-30

Highlights: • DNA in spintronics is applied. Nearly pure spin current is observed in the system. • A combined spin-polaronic PBH model is proposed for spin transfer in DNA molecule. • Spin Hall effect in DNA due to spin–orbit coupling is verified. • The temperature dependence of Hall conductivity is appeared. • Regions of parameters were determined that polarization of spin current is maximum. - Abstract: Experimental results show that the photoelectrons emitted from the gold substrate due to laser radiation, passe through DNA nanowires with spin-polarized nature. This study proposes the use of chiral DNA molecule in spintronics and information processing. To investigate the spin transfer in DNA molecules, we established a theoretical model based on a combined spin-polaronic Peyrard–Bishop–Holstein model. Accordingly, a nearly pure spin current is appeared. The simultaneous effects of the incident radiation and external magnetic field create characteristic islands corresponding to the pure spin currents, which can be predicted and detected using the multifractal dimensions spectrum. We can verify the spin Hall effect on DNA oligomers through spin–orbit coupling. As such, we can proceed to our significant purpose, which is to create a nearly pure spin current for information transfer and determine the regions of parameter values from which the maximal polarization in spin current emerges.