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Sample records for 3he spin filters

  1. 3He Spin Filter for Neutrons

    PubMed Central

    Batz, M.; Baeßler, S.; Heil, W.; Otten, E. W.; Rudersdorf, D.; Schmiedeskamp, J.; Sobolev, Y.; Wolf, M.

    2005-01-01

    The strongly spin-dependent absorption of neutrons in nuclear spin-polarized 3He opens up the possibility of polarizing neutrons from reactors and spallation sources over the full kinematical range of cold, thermal and hot neutrons. This paper gives a report on the neutron spin filter (NSF) development program at Mainz. The polarization technique is based on direct optical pumping of metastable 3He atoms combined with a polarization preserving mechanical compression of the gas up to a pressure of several bar, necessary to run a NSF. The concept of a remote type of operation using detachable NSF cells is presented which requires long nuclear spin relaxation times of order 100 hours. A short survey of their use under experimental conditions, e.g. large solid-angle polarization analysis, is given. In neutron particle physics NSFs are used in precision measurements to test fundamental symmetry concepts. PMID:27308139

  2. Polarized 3He Spin Filters for Slow Neutron Physics

    PubMed Central

    Gentile, T. R.; Chen, W. C.; Jones, G. L.; Babcock, E.; Walker, T. G.

    2005-01-01

    Polarized 3He spin filters are needed for a variety of experiments with slow neutrons. Their demonstrated utility for highly accurate determination of neutron polarization are critical to the next generation of betadecay correlation coefficient measurements. In addition, they are broadband devices that can polarize large area and high divergence neutron beams with little gamma-ray background, and allow for an additional spin-flip for systematic tests. These attributes are relevant to all neutron sources, but are particularly well-matched to time of flight analysis at spallation sources. There are several issues in the practical use of 3He spin filters for slow neutron physics. Besides the essential goal of maximizing the 3He polarization, we also seek to decrease the constraints on cell lifetimes and magnetic field homogeneity. In addition, cells with highly uniform gas thickness are required to produce the spatially uniform neutron polarization needed for beta-decay correlation coefficient experiments. We are currently employing spin-exchange (SE) and metastability-exchange (ME) optical pumping to polarize 3He, but will focus on SE. We will discuss the recent demonstration of 75 % 3He polarization, temperature-dependent relaxation mechanism of unknown origin, cell development, spectrally narrowed lasers, and hybrid spin-exchange optical pumping. PMID:27308140

  3. Optimised adiabatic fast passage spin flipping for 3He neutron spin filters

    NASA Astrophysics Data System (ADS)

    McKetterick, T. J.; Boag, S.; Stewart, J. R.; Frost, C. D.; Skoda, M. W. A.; Parnell, S. R.; Babcock, E.

    2011-06-01

    We describe here a method of performing adiabatic fast passage (AFP) spin flipping of polarized 3He used as a neutron spin filter (NSF) to polarize neutron beams. By reversing the spin states of the 3He nuclei the polarization of a neutron beam can be efficiently reversed allowing for the transmission of a neutron beam polarized in either spin state. Using an amplitude modulated frequency sweep lasting 500 ms we can spin flip a polarized 3He neutron spin filter with only 1.8×10-5 loss in 3He polarization. The small magnetic fields (10-15 G) used to house neutron spin filters mean the 3He resonant frequencies are low enough to be generated using a computer with a digital I/O card. The versatility of this systems allows AFP to be performed on any beamline or in any laboratory using 3He neutron spin filters and polarization losses can be minimised by adjusting sweep parameters.

  4. A compact SEOP 3He neutron spin filter with AFP NMR

    NASA Astrophysics Data System (ADS)

    Ino, Takashi; Arimoto, Yasushi; Shimizu, Hirohiko M.; Sakaguchi, Yoshifumi; Sakai, Kenji; Kira, Hiroshi; Shinohara, Takenao; Oku, Takayuki; Suzuki, Jun-ichi; Kakurai, Kazuhisa; Chang, Lieh-Jeng

    2012-02-01

    We developed AFP NMR in an aluminum container for polarized noble gas nuclei. The radio frequency magnetic field inside the aluminum container was designed from computer simulations. The polarization loss by the AFP spin flip of 3He was measured to be as low as 3.8×10-4. With this technique, a compact in-situ polarizing 3He neutron spin filter with AFP NMR is demonstrated.

  5. ^3He Spin Pump

    NASA Astrophysics Data System (ADS)

    Yamaguchi, A.; Ishimoto, H.; Kojima, H.

    2009-03-01

    The superfluid component of ^3He A1 phase is spin-polarized. The process of forcing the superfluid component through a spin filtering structure, in a manner of mechano-magnetic effect, can be used to increase the spin polarization beyond the equilibrium under a given applied magnetic field. We have constructed a test cell in which a glass capillary array acts as the spin (and entropy) filter and an electrostatically actuated diaphragm forces the superfluid flow through it. Preliminary results show that a maximum relative increase of polarization by 50 % could be achieved. The maximum increase in polarization appears to be limited by the critical superfluid flow through the channels in the glass capillary array. The dependence of the observed effects on temperature, pressure and magnetic field will be presented.

  6. Recent advances in polarized 3 He based neutron spin filter development

    NASA Astrophysics Data System (ADS)

    Chen, Wangchun; Gentile, Thomas; Erwin, Ross; Watson, Shannon; Krycka, Kathryn; Ye, Qiang; NCNR NIST Team; University of Maryland Team

    2015-04-01

    Polarized 3 He neutron spin filters (NSFs) are based on the strong spin-dependence of the neutron absorption cross section by 3 He. NSFs can polarize large area, widely divergent, and broadband neutron beams effectively and allow for combining a neutron polarizer and a spin flipper into a single polarizing device. The last capability utilizes 3 He spin inversion based on the adiabatic fast passage (AFP) nuclear magnetic resonance technique. Polarized 3 He NSFs are significantly expanding the polarized neutron measurement capabilities at the NIST Center for Neutron Research (NCNR). Here we present an overview of 3 He NSF applications to small-angle neutron scattering, thermal triple axis spectrometry, and wide-angle polarization analysis. We discuss a recent upgrade of our spin-exchange optical pumping (SEOP) systems that utilize chirped volume holographic gratings for spectral narrowing. The new capability allows us to polarize rubidium/potassium hybrid SEOP cells over a liter in volume within a day, with 3 He polarizations up to 88%, Finally we discuss how we can achieve nearly lossless 3 He polarization inversion with AFP.

  7. A New Method for Precision Cold Neutron Polarimetry Using a 3He Spin Filter

    PubMed Central

    Wietfeldt, F. E.; Gentile, T. R.

    2005-01-01

    We present a new method for precision measurement of the capture flux polarization of a polychromatic (white), continuous cold neutron beam, polarized by a 3He spin filter. This method allows an in situ measurement and does not require knowledge of the neutron beam wavelength distribution. We show that a polarimetry precision of 0.1 % is possible.

  8. SEOP polarized 3He Neutron Spin Filters for the JCNS user program

    NASA Astrophysics Data System (ADS)

    Babcock, Earl; Salhi, Zahir; Theisselmann, Tobias; Starostin, Denis; Schmeissner, Johann; Feoktystov, Artem; Mattauch, Stefan; Pistel, Patrick; Radulescu, Aurel; Ioffe, Alexander

    2016-04-01

    Over the past several years the JCNS has been developing in-house applications for neutron polarization analysis (PA). These methods include PA for separation of incoherent from coherent scattering in soft matter studies (SANS), and online polarization for analysis for neutron reflectometry, SANS, GISANS and eventually spectroscopy. This paper will present an overview of the user activities at the JCNS at the MLZ and gives an overview of the polarization 3He methods and devices used. Additionally we will summarise current projects which will further support the user activities using polarised 3He spin filters.

  9. SQUID measurements of remanent magnetisation in refillable 3He spin-filter cells (SFC)

    NASA Astrophysics Data System (ADS)

    Hutanu, V.; Rupp, A.; Sander-Thömmes, T.

    2007-07-01

    A strong influence of external magnetic fields on the relaxation time constant T1 of glass cells serving as reservoirs for polarised 3He, observed for various alkali metal-coated cells made of different glass types, was initially associated with the presence of a large number of ferromagnetic clusters on the glass surface. Later experiments showed the presence of the so-called “ T1 hysteresis” phenomenon with a similar distinctiveness also in uncoated cells made of pure synthetic quartz glass. It suggests that the origin of such a relaxation is a macroscopic magnetisation in the bulk of the cell. We present the results of a multi-SQUID system investigation on magnetised and non-magnetised quartz glass cells, Cs coated as well as bare wall, to be used as neutron spin filters at HMI Berlin. The presence of a macroscopic remanent magnetic moment in the cells after their exposition to external magnetic fields has been experimentally shown. More than 80% of the remanent magnetic moment of the magnetised cells was found to be concentrated in the region of the glass valves. SQUID measurements reveal the existence of some remanent magnetisation in all valve parts and also in the vacuum grease, but most magnetic are the plastic parts and the O-ring. Different valve and sealing types have been compared in order to find the less magnetisable one.

  10. Conceptual design of a polarized 3He neutron spin filter for polarized neutron spectrometer POLANO at J-PARC

    NASA Astrophysics Data System (ADS)

    Ino, T.; Ohoyama, K.; Yokoo, T.; Itoh, S.; Ohkawara, M.; Kira, H.; Hayashida, H.; Sakai, K.; Hiroi, K.; Oku, T.; Kakurai, K.; Chang, L. J.

    2016-04-01

    A 3He neutron spin filter (NSF) has been designed for a new polarized neutron chopper spectrometer called the Polarization Analysis Neutron Spectrometer with Correlation Method (POLANO) at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. It is designed to fit in a limited space on the spectrometer as an initial neutron beam polarizer and is polarized in situ by spin exchange optical pumping. This will be the first generation 3He NSF on POLANO, and a polarized neutron beam up to 100 meV with a diameter of 50 mm will be available for research on magnetism, hydrogen materials, and strongly correlated electron systems.

  11. Development of a 3He nuclear spin flip system on an in-situ SEOP 3He spin filter and demonstration for a neutron reflectometer and magnetic imaging technique

    NASA Astrophysics Data System (ADS)

    Hayashida, H.; Oku, T.; Kira, H.; Sakai, K.; Hiroi, K.; Ino, T.; Shinohara, T.; Imagawa, T.; Ohkawara, M.; Ohoyama, K.; Kakurai, K.; Takeda, M.; Yamazaki, D.; Oikawa, K.; Harada, M.; Miyata, N.; Akutsu, K.; Mizusawa, M.; Parker, J. D.; Matsumoto, Y.; Zhang, S.; Suzuki, J.; Soyama, K.; Aizawa, K.; Arai, M.

    2016-04-01

    We have been developing a 3He neutron spin filter (NSF) using the spin exchange optical pumping (SEOP) technique. The 3He NSF provides a high-energy polarized neutron beam with large beam size. Moreover the 3He NSF can work as a π-flipper for a polarized neutron beam by flipping the 3He nuclear spin using a nuclear magnetic resonance (NMR) technique. For NMR with the in-situ SEOP technique, the polarization of the laser must be reversed simultaneously because a non-reversed laser reduces the polarization of the spin-flipped 3He. To change the polarity of the laser, a half-wavelength plate was installed. The rotation angle of the half-wavelength plate was optimized, and a polarization of 97% was obtained for the circularly polarized laser. The 3He polarization reached 70% and was stable over one week. A demonstration of the 3He nuclear spin flip system was performed at the polarized neutron reflectometer SHARAKU (BL17) and NOBORU (BL10) at J-PARC. Off-specular measurement from a magnetic Fe/Cr thin film and magnetic imaging of a magnetic steel sheet were performed at BL17 and BL10, respectively.

  12. End-compensated magnetostatic cavity for polarized 3He neutron spin filters.

    PubMed

    McIver, J W; Erwin, R; Chen, W C; Gentile, T R

    2009-06-01

    We have expanded upon the "Magic Box" concept, a coil driven magnetic parallel plate capacitor constructed out of mu-metal, by introducing compensation sections at the ends of the box that are tuned to limit end-effects similar to those of short solenoids. This ability has reduced the length of the magic box design without sacrificing any loss in field homogeneity, making the device far more applicable to the often space limited neutron beam line. The appeal of the design beyond affording longer polarized 3He lifetimes is that it provides a vertical guide field, which facilitates neutron spin transport for typical polarized beam experiments. We have constructed two end-compensated magic boxes of dimensions 28.4 x 40 x 15 cm3 (length x width x height) with measured, normalized volume-averaged transverse field gradients ranging from 3.3 x 10(-4) to 6.3 x 10(-4) cm(-1) for cell sizes ranging from 8.1 x 6.0 to 12.0 x 7.9 cm2 (diameter x length), respectively. PMID:19566213

  13. Neutron spin filters (NSF) obtained by metastability-exchange optical pumping (MEOP) and mechanical compressing of 3He gas

    NASA Astrophysics Data System (ADS)

    Hutanu, V.; Habicht, Klaus; Rupp, A.

    2004-10-01

    NSF using gaseous polarized 3He became a popular tool for many polarized neutron scattering applications due to the number of advantages that this technique presents, but also due to significant increasing of technical performancies demonstrated in that field in the last years. The realization of flexible and reliable devices for neutron beam polarization is a focal point in the instrumental development program at the Hahn-Meitner Institute Berlin (HMI). The technique applied in our case to obtain nuclear-spin-polarized 3He is metastability-exchange optical pumping (MEOP) using a cw Nd:LNA laser with 5.8 W output power and 2.5 GHz bandwidth. The general aspects regarding optical pumping in optical polarizing cells are described. The construction of the optical pumping volume is presented, the last results regarding optical pumping cells (OPC) and filter cells preparation are discussed. The status and perspectives of the project are presented.

  14. Spin Duality on the Neutron (^3He)

    SciTech Connect

    Solvignon, Patricia

    2007-02-01

    Thomas Jefferson National Accelerator Facility experiment E01-012 measured the 3He spin structure functions and virtual photon asymmetries in the resonance region in the momentum transfer range 1.0 < Q2 < 4.0 (GeV/c)2. Our date, when compared with existing deep inelastic scattering data, can be used to test quark-hadron duality in g1 and A1 for 3He and the neutron. Preliminary results for A{sub 1}{sup {sup 3}He} are presented, as well as some details about the experiment.

  15. Packed Powder as Superleak for Spin Pump Experiments in Superfluid 3He A1

    NASA Astrophysics Data System (ADS)

    Kamada, N.; Yamaguchi, A.; Motoyama, G.; Sumiyama, A.; Aoki, Y.; Okuda, Y.; Kojima, H.

    2014-04-01

    Experimental exploration of highly spin-polarized states of liquid 3He by applying external magnetic field is limited by the availability of static magnetic field. In the "ferromagnetic" superfluid A1 phase of liquid 3He there is an alternate method for boosting spin-polarization by the process of spin pumping without requiring such high magnetic field. The spin pumping in the A1 phase takes advantage of a superleak (SL) acting simultaneously as a filter for both entropy and spin. The spin pump technique that uses the SL-spin filter and a mechanical actuator enables us to directly boost polarization of 3He. The amount of enhancement of spin polarization has been limited so far. We are now developing a new type of SL filter made of packed aluminum oxide powder (referred as PAP-SL), in order to achieve greater enhancement of spin polarization. Several kinds of the PAP-SL filter were constructed by pressing aluminum oxide powders into a cylinder holder. The packed structures were carefully characterized by a flow-rate-measurement, X-ray tomography, and mercury intrusion porosimetry. The preliminary result shows that the PAP-SL works as SL filter for the superfluid 3He.

  16. Dressed spin of polarized {sup 3}He in a cell

    SciTech Connect

    Chu, P.-H.; Esler, A. M.; Peng, J. C.; Beck, D. H.; Chandler, D. E.; Clayton, S.; Williamson, S.; Yoder, J.; Hu, B.-Z.; Ngan, S. Y.; Sham, C. H.; So, L. H.

    2011-08-15

    We report a measurement of the modification of the effective precession frequency of polarized {sup 3}He atoms in response to a dressing field in a room-temperature cell. The {sup 3}He atoms were polarized using the metastability spin-exchange method. An oscillating dressing field was then applied perpendicular to the constant magnetic field. Modification of the {sup 3}He effective precession frequency was observed over a broad range of the amplitude and frequency of the dressing field. The observed effects are compared with calculations based on quantum optics formalism.

  17. Dressed spin of polarized 3He in a cell

    NASA Astrophysics Data System (ADS)

    Chu, P.-H.; Esler, A. M.; Peng, J. C.; Beck, D. H.; Chandler, D. E.; Clayton, S.; Hu, B.-Z.; Ngan, S. Y.; Sham, C. H.; So, L. H.; Williamson, S.; Yoder, J.

    2011-08-01

    We report a measurement of the modification of the effective precession frequency of polarized 3He atoms in response to a dressing field in a room-temperature cell. The 3He atoms were polarized using the metastability spin-exchange method. An oscillating dressing field was then applied perpendicular to the constant magnetic field. Modification of the 3He effective precession frequency was observed over a broad range of the amplitude and frequency of the dressing field. The observed effects are compared with calculations based on quantum optics formalism.

  18. Quark-Hadron Duality in Neutron (3He) Spin Structure

    SciTech Connect

    Solvignon, Patricia; Liyanage, Nilanga; Chen, Jian-Ping; Choi, Seonho; Aniol, Konrad; Averett, Todd; Boeglin, Werner; Camsonne, Alexandre; Cates, Gordon; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chudakov, Eugene; Craver, Brandon; Cusanno, Francesco; Deur, Alexandre; Dutta, Dipangkar; Ent, Rolf; Feuerbach, Robert; Frullani, Salvatore; Gao, Haiyan; Garibaldi, Franco; Gilman, Ronald; Glashausser, Charles; Gorbenko, Viktor; Hansen, Jens-Ole; Higinbotham, Douglas; Ibrahim, Hassan; Jiang, Xiaodong; Jones, Mark; Kelleher, Aidan; Kelly, J.; Keppel, Cynthia; Kim, Wooyoung; Korsch, Wolfgang; Kramer, Kevin; Kumbartzki, Gerfried; LeRose, John; Lindgren, Richard; Ma, Bin; Margaziotis, Demetrius; Markowitz, Pete; McCormick, Kathy; Meziani, Zein-Eddine; Michaels, Robert; Moffit, Bryan; Monaghan, Peter; Munoz-Camacho, Carlos; Paschke, Kent; Reitz, Bodo; Saha, Arunava; Sheyor, Ran; Singh, Jaideep; Slifer, Karl; Sulkosky, Vince; Sulkosky, Vincent; Sulkosky, Vince; Sulkosky, Vincent; Tobias, William; Urciuoli, Guido; Wang, Kebin; Wijesooriya, Krishni; Wojtsekhowski, Bogdan; Woo, Seungtae; Yang, Jae-Choon; Zheng, Xiaochao; Zhu, Lingyan

    2008-10-01

    We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2.

  19. Recent Spin Pump Experiments on Superfluid 3He-A1

    NASA Astrophysics Data System (ADS)

    Yamaguchi, A.; Kamada, N.; Motoyama, G.; Sumiyama, A.; Aoki, Y.; Okuda, Y.; Kubota, M.; Kojima, H.

    2013-05-01

    The superfluid 3He A1 phase, containing a spin-polarized condensate allows us to explore the dynamics of superfluid spin current. In the mechano-spin effect (MSE), a mechanically applied pressure gradient and a superleak-spin filter enable one to directly boost spin polarization of 3He in a small chamber. We are developing new apparatus for achieving greater enhancement of spin density. A development of a new-type 3He-hydraulic actuator has been already reported. We present here the construction of new-type of superleak-spin-filter made of packed powder aluminum oxide (referred as PAP-SL). The PAP-SL is popular in the study of superfluid 4He, but has not been established for that of the superfluid 3He. The attempt to construct the PAP-SL for the spin pump experiment was made by using aluminum oxide powder with nominal 1 μm powder diameter and with packing fraction of 40 %. Before executing the experiment, the nuclear demagnetization cryostat of ISSP, Univ. Tokyo which has been used for this experimental activity, was heavily damaged by the 2011 Great East Japan (Higashi Nihon) Earthquake. The repair work and earthquake damage protection strengthening has just been accomplished.

  20. High Efficiency Spin Flipper for the n3He Experiment

    NASA Astrophysics Data System (ADS)

    Hayes, Christopher; n3He Collaboration

    2015-10-01

    The n3He experiment, constructed on the Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source, is designed to measure the parity violating (PV) proton asymmetry Ap in the capture reaction n +3 He -->3 H + p + 765 keV The asymmetry has an estimated value Ap ~ - 1 ×10-7 and is directly related to the weak isospin conserved couplings hρ0 and ωρ0 which are of fundamental interest in the verification of the meson exchange model of low energy NN intereactions. Data production for the n3He experiment began in February 2015 and is scheduled to continue thru December 2015 - reaching a statistical sensitivity δAp ~10-8 or better. I will discuss the spin flipper which is designed using the theory of double cosine-theta coils, and capable of flipping neutron spins with an efficiency approaching its maximum value ɛsf = 1 . I will also discuss the theory of Spin Magnetic Resonance (SMR) and how it is employed by the spin flipper to flip 60 Hz pulses of cold neutrons over a range of wavelengths.

  1. Thermal Conductivity of Spin-Polarized Liquid {sup 3}He

    SciTech Connect

    Sawkey, D.; Puech, L.; Wolf, P.E.

    2006-06-02

    We present the first measurements of the thermal conductivity of spin-polarized normal liquid {sup 3}He. Using the rapid melting technique to produce nuclear polarizations up to 0.7, and a vibrating wire both as a heater and a thermometer, we show that, unlike the viscosity, the conductivity increases much less than predicted for s-wave scattering. We suggest that this might be due to a small probability for head-on collisions between quasiparticles.

  2. 3He Spin-Dependent Cross Sections and Sum Rules

    SciTech Connect

    Slifer, Karl; Amaryan, Moscov; Amaryan, Moskov; Auerbach, Leonard; Averett, Todd; Berthot, J.; Bertin, Pierre; Bertozzi, William; Black, Tim; Brash, Edward; Brown, D.; Burtin, Etienne; Calarco, John; Cates, Gordon; Chai, Zhengwei; Chen, Jian-Ping; Choi, Seonho; Chudakov, Eugene; Ciofi, Claudio; Cisbani, Evaristo; De Jager, Cornelis; Deur, Alexandre; DiSalvo, R.; Dieterich, Sonja; Djawotho, Pibero; Finn, John; Fissum, Kevin; Fonvieille, Helene; Frullani, Salvatore; Gao, Haiyan; Gao, Juncai; Garibaldi, Franco; Gasparian, Ashot; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Glashausser, Charles; Glockle, W.; Golak, J.; Goldberg, Emma; Gomez, Javier; Gorbenko, Viktor; Hansen, Jens-Ole; Hersman, F.; Holmes, Richard; Huber, Garth; Hughes, Emlyn; Humensky, Thomas; Incerti, Sebastien; Iodice, Mauro; Jensen, S.; Jiang, Xiaodong; Jones, C.; Jones, G.; Jones, Mark; Jutier, Christophe; Kamada, H.; Ketikyan, Armen; Kominis, Ioannis; Korsch, Wolfgang; Kramer, Kevin; Kumar, Krishna; Kumbartzki, Gerfried; Kuss, Michael; Lakuriqi, Enkeleida; Laveissiere, Geraud; LeRose, John; Liang, Meihua; Liyanage, Nilanga; Lolos, George; Malov, Sergey; Marroncle, Jacques; McCormick, Kathy; McKeown, Robert; Meziani, Zein-Eddine; Michaels, Robert; Mitchell, Joseph; Nogga, Andreas; Pace, Emanuele; Papandreou, Zisis; Pavlin, Tina; Petratos, Gerassimos; Pripstein, David; Prout, David; Ransome, Ronald; Roblin, Yves; Rowntree, David; Rvachev, Marat; Sabatie, Franck; Saha, Arunava; Salme, Giovanni; SCOPETTA, S.; Skibinski, R.; Souder, Paul; Saito, Teijiro; Strauch, Steffen; Suleiman, Riad; Takahashi, Kazunori; Todor, Luminita; Tsubota, Hiroaki; Ueno, Hiroaki; Urciuoli, Guido; van der Meer, Rob; Vernin, Pascal; Voskanyan, Hakob; Witala, Henryk; Wojtsekhowski, Bogdan; Xiong, Feng; Xu, Wang; Yang, Jae-Choon; Zhang, Bin; Zolnierczuk, Piotr

    2008-07-01

    We present a measurement of the spin-dependent cross sections for the \\vec{^3He}(\\vec{e},e')X} reaction in the quasielastic and resonance regions at four-momentum transfer 0.1 < Q^2< 0.9 GeV^2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt--Cottingham and extended GDH sum rules for the first time. Impulse approximation and exact three-body Faddeev calculations are also compared to the data in the quasielastic region.

  3. Compressing Spin-Polarized 3He With a Modified Diaphragm Pump

    PubMed Central

    Gentile, T. R.; Rich, D. R.; Thompson, A. K.; Snow, W. M.; Jones, G. L.

    2001-01-01

    Nuclear spin-polarized 3He gas at pressures on the order of 100 kPa (1 bar) are required for several applications, such as neutron spin filters and magnetic resonance imaging. The metastability-exchange optical pumping (MEOP) method for polarizing 3He gas can rapidly produce highly polarized gas, but the best results are obtained at much lower pressure (~0.1 kPa). We describe a compact compression apparatus for polarized gas that is based on a modified commercial diaphragm pump. The gas is polarized by MEOP at a typical pressure of 0.25 kPa (2.5 mbar), and compressed into a storage cell at a typical pressure of 100 kPa. In the storage cell, we have obtained 20 % to 35 % 3He polarization using pure 3He gas and 35 % to 50 % 3He polarization using 3He-4He mixtures. By maintaining the storage cell at liquid nitrogen temperature during compression, the density has been increased by a factor of four. PMID:27500044

  4. Spin echo small angle neutron scattering using a continuously pumped {sup 3}He neutron polarisation analyser

    SciTech Connect

    Parnell, S. R.; Li, K.; Yan, H.; Stonaha, P.; Li, F.; Wang, T.; Baxter, D. V.; Snow, W. M.; Washington, A. L.; Walsh, A.; Chen, W. C.; Parnell, A. J.; Fairclough, J. P. A.; Pynn, R.

    2015-02-15

    We present a new instrument for spin echo small angle neutron scattering (SESANS) developed at the Low Energy Neutron Source at Indiana University. A description of the various instrument components is given along with the performance of these components. At the heart of the instrument are a series of resistive coils to encode the neutron trajectory into the neutron polarisation. These are shown to work well over a broad range of neutron wavelengths. Neutron polarisation analysis is accomplished using a continuously operating neutron spin filter polarised by Rb spin-exchange optical pumping of {sup 3}He. We describe the performance of the analyser along with a study of the {sup 3}He polarisation stability and its implications for SESANS measurements. Scattering from silica Stöber particles is investigated and agrees with samples run on similar instruments.

  5. Polarization of 3He by Spin Exchange with Optically Pumped Rb and K Vapors

    NASA Astrophysics Data System (ADS)

    Ben-Amar Baranga, A.; Appelt, S.; Romalis, M. V.; Erickson, C. J.; Young, A. R.; Cates, G. D.; Happer, W.

    1998-03-01

    We report on extensive experimental measurements of the key rates that determine the efficiency for polarizing the nuclei of 3He by spin exchange with optically pumped Rb vapor. In agreement with recent theoretical predictions, we find a strong temperature dependence of the electron-spin loss rates due to 3HeRb collisions. We also find that the maximum possible efficiency for spin-exchange polarization of 3He by K is 10 times greater than for Rb.

  6. SPECIAL ISSUE DEVOTED TO THE 80TH ANNIVERSARY OF ACADEMICIAN N G BASOV'S BIRTH: An optically polarised dense 3He target as a spin filter for slow-neutron beams

    NASA Astrophysics Data System (ADS)

    Kolachevsky, Nikolai N.; Prokof'ichev, Yu V.; Skoi, V. R.; Sobel'man, Igor I.; Sorokin, Vadim N.

    2003-01-01

    The possibility of polarising 3He and preserving the polarisation in an external magnetic field of 0.05 Oe is demonstrated experimentally. A neutron filter with an extremely weak guiding field is fabricated for obtaining polarised neutron beams. The degree of polarisation equal to 25% was obtained for 0.025-eV neutrons. Some fields of application of other polarised noble gases are considered. The cross section for cross-relaxation of nuclear polarisation in the 129Xe — 131Xe mixture is estimated.

  7. Nuclear spin heat capacity of 3He adsorbed on graphite

    NASA Astrophysics Data System (ADS)

    Greywall, Dennis S.

    1989-10-01

    The heat capacity of 3He adsorbed on graphite has been measured for films between one and five atomic layers and for temperatures between 2 and 200 mK. These results are compared with recent magnetization data which also show several anomalies in this coverage regime. Prior to third layer promotion the second layer is found to solidify into a registered structure with unusual propertis. This contradicts the model proposed to explain the NMR measurements.

  8. Highlights of JLab Neutron (3He) Spin Program

    SciTech Connect

    Jian-ping Chen

    2009-07-01

    Nucleon spin structure has been an active, exciting and intriguing subject of interest for the last three decades. Recent precision spin-structure data from Jefferson Lab have significantly advanced our knowledge of nucleon structure at low Q2. In particular, it has improved our understanding of spin sum rules and higher-twist effects. First, results of neutron spin sum rules and polarizabilities in the low to intermediate Q2 region are presented. Comparison with theoretical calculations, in particular with Chiral Perturbation Theory (ChPT) calculations, are discussed. Surprising disagreements of ChPT calculations with experimental results on the generalized spin polarizability, deltaLTn, were found. Results of precision measurements of the g2 structure function to study higher-twist effects are presented. The data indicate a significant higher-twist (twist-3 or higher) effect. The second moment of the spin structure functions and the twist-3 matrix element d2 results were extracted. The high Q2 result was compared with a Lattice QCD calculation. Finally, other neutron spin structure results, such as the resonance data for quark-hadron duality study and a precision measurement of the neutron spin asymmetry in the valence quark (high-x) region are briefly discussed.

  9. On the limits of spin-exchange optical pumping of 3 He

    NASA Astrophysics Data System (ADS)

    Gentile, T. R.; Chen, W. C.; Ye, Q.; Walker, T. G.; Babcock, E.

    2015-04-01

    We have obtained improvement in the 3 He polarization achievable by spin-exchange optical pumping (SEOP). These results were primarily obtained in large neutron spin filter cells using diode bar lasers spectrally narrowed with chirped volume holographic gratings. As compared to our past results with lasers narrowed with diffraction gratings, we have observed between 5% and 11% fractional increase in the 3 He polarization PHe. We also report a comparable improvement in PHe for two small cells, for which we would not have expected an increase from improved laser performance. In particular, prior extensive studies had indicated that the alkali-metal polarization was within 3% of unity in one of these cells. These results have impact on understanding the maximum PHe achievable by SEOP, whether the origin of the improvement is from increased alkali-metal polarization or decreased temperature-dependent relaxation. We have observed PHe of between 0.80 and 0.85 in several large cells, which marks a new precedent for the polarization achievable by SEOP. Recently we have obtained PHe as high as 0.88 with increased laser power. We will discuss these results and tests performed to understand their origin.

  10. On the limits of spin-exchange optical pumping of {sup 3}He

    SciTech Connect

    Chen, W. C. Ye, Q.; Gentile, T. R.; Walker, T. G.; Babcock, E.

    2014-07-07

    We have obtained improvement in the {sup 3}He polarization achievable by spin-exchange optical pumping (SEOP). These results were primarily obtained in large neutron spin filter cells using diode bar lasers spectrally narrowed with chirped volume holographic gratings. As compared to our past results with lasers narrowed with diffraction gratings, we have observed between 5% and 11% fractional increase in the {sup 3}He polarization P{sub He}. We also report a comparable improvement in P{sub He} for two small cells, for which we would not have expected an increase from improved laser performance. In particular, prior extensive studies had indicated that the alkali-metal polarization was within 3% of unity in one of these cells. These results have impact on understanding the maximum P{sub He} achievable by SEOP, whether the origin of the improvement is from increased alkali-metal polarization or decreased temperature-dependent relaxation. We conclude that the most likely explanation for the improvement in P{sub He} is increased alkali-metal polarization. We have observed P{sub He} of between 0.80 and 0.85 in several large cells, which marks a new precedent for the polarization achievable by SEOP.

  11. Spin Correlation Parameter Cyy of p + 3He Elastic Backward Scattering at Intermediate Energy

    NASA Astrophysics Data System (ADS)

    Shimizu, Y.; Hatanaka, K.; Adachi, T.; Itoh, K. F. K.; Kawabata, T.; Kudoh, T.; Ohira, H. M. H.; Okamura, H.; Sagara, K.; Sasamoto, Y. S. Y.; Yoshida, Y. S. H. P.; Suda, K.; Tomiyama, Y. T. A. T. M.; Uesaka, M. U. T.; Wakasa, T.; Wakui, T.

    2005-08-01

    It is possible to use nucleon-nucleus scattering as a probe of the spin structure of nuclei, since target related observables are extremely sensitive to small spin-dependent parts of the target wave function. In addition, one can gain information about the nucleon-nucleus reaction mechanism, the spin dependence of the nucleon-nucleon interaction in the nuclear medium, and off-shell behavior of the nucleon-nucleon amplitudes. For 3He(p,3He)p elastic backward scattering (EBS), only a small amount of data exists for the differential cross-section and none exists for spin-dependent observables. We have developed a spin-exchange polarised 3He target and measured the spin correlation parameter Cyy at 200, 300, and 400 MeV.

  12. Spin Correlation Parameter Cyy of p + 3He Elastic Backward Scattering at Intermediate Energy

    NASA Astrophysics Data System (ADS)

    Shimizu, Y.; Hatanaka, K.; Kobushkin, A. P.; Adachi, T.; Fujita, K.; Itoh, K.; Kawabata, T.; Kudoh, T.; Matsubara, H.; Ohira, H.; Okamura, H.; Sagara, K.; Sakemi, Y.; Sasamoto, Y.; Shimbara, Y.; Yoshida, H. P.; Suda, K.; Tameshige, Y.; Tamii, A.; Tomiyama, M.; Uchida, M.; Uesaka, T.; Wakasa, T.; Wakui, T.

    2007-01-01

    It is possible to use nucleon-nucleus scattering as a probe of the spin structure of the nuclei since target related observables are extremely sensitive to spin dependent parts of the target wave function. In addition, one can gain information about the nucleon-nucleus reaction mechanism, the spin dependent nucleon-nucleon interaction in the nuclear medium, and off-shell behavior of the nucleon-nucleon amplitudes. For 3He(p,3He)p elastic backward scattering, only small amount of data points exist for the differential cross section and no data exist for spin dependent observables. We developed a spin exchange type polarized 3He target and measured the spin correlation parameter Cyy at 200, 300, and 400 MeV.

  13. Progress Towards the Detection of Faraday Rotation on Spin Polarized 3He

    NASA Astrophysics Data System (ADS)

    Abney, Josh; Broering, Mark; Korsch, Wolfgang

    2016-03-01

    Off-resonance Faraday rotation can offer a new method to monitor the nuclear spin polarization of a dense 3He target and gain access to new information about the magnetic polarizability of the 3He nucleus. The interaction of the polarization state of light with the nuclear spin of the helium atom is very weak and has never been detected. A sensitive triple modulation technique has been developed which can detect the expected rotation angle on the order of 100 nrad. Once a Faraday rotation signal is observed, the next step is to separate the magnetic and electric contributions to the rotation by utilizing their different frequency dependencies. Recent studies involved optimizing several parameters which impact 3He target polarization. Progress towards detecting nuclear spin optical rotation on 3He will be reported. This research is supported by DOE Grant DE-FG02-99ER41101.

  14. Magnetization and spin diffusion of liquid {sup 3}He in aerogel

    SciTech Connect

    Sauls, J. A.; Bunkov, Yu.M.; Collin, E.; Godfrin, H.; Sharma, P.

    2005-07-01

    We report theoretical calculations and experimental measurements of the normal-state spin diffusion coefficient of {sup 3}He in aerogel, including both elastic and inelastic scattering of {sup 3}He quasiparticles, and compare these results with data for {sup 3}He in 98% porous silica aerogel. This analysis provides a determination of the elastic mean free path within the aerogel. Measurements of the magnetization of the superfluid phase in the same aerogel samples provide a test of the theory of pairbreaking and magnetic response of low-energy excitations in the 'dirty' B phase of {sup 3}He in aerogel. A consistent interpretation of the data for the spin-diffusion coefficient, magnetization, and superfluid transition temperature is obtained by including correlation effects in the aerogel density.

  15. Progress Towards the Detection of Faraday Rotation on Spin Polarized 3He

    NASA Astrophysics Data System (ADS)

    Abney, Joshua; Broering, Mark; Korsch, Wolfgang

    2016-05-01

    Off-resonance Faraday rotation can offer a method to measure the nuclear spin optical rotation of the 3 He nucleus and gain access to new information about the atomic polarizability of the Helium atom. The interaction of the polarization state of light with the nuclear spin of the helium atom is very weak and has never been detected. A sensitive triple modulation technique has been developed which can detect the expected rotation angle on the order of 100 nrad. Once a Faraday rotation signal is observed, the next step is to separate the magnetic and electric contributions to the rotation by utilizing their different frequency dependencies. Recent studies involved optimizing several parameters which impact 3 He target polarization. Progress towards detecting nuclear spin optical rotation on 3 He will be reported. This research is supported by DOE Grant DE-FG02-99ER41101.

  16. The Neutron and 3He Spin Structure Functions at Low Q^2

    SciTech Connect

    Vincent Sulkosky

    2009-08-01

    Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility in Hall A to provide a precise measurement of the moments of the neutron and $^{3}$He spin structure functions. A longitudinally-polarized electron beam was scattered from a longitudinally or transversely polarized $^{3}$He target. The extended Gerasimov-Drell-Hearn integral and other moments of the neutron and $^{3}$He spin structure functions were extracted at very low momentum transfers (0.02 $< Q^{2} <$ 0.3 [GeV$/c$]$^{2}$). These data allow us to make a benchmark check of Chiral Perturbation Theory calculations in a region where they are expected to be valid. In these proceedings, the experimental details are discussed and preliminary results on the moments of the spin structure functions are presented.

  17. Low-temperature instability of uniform spin precession in the B phase of pure {sup 3}He and {sup 3}He in an aerogel

    SciTech Connect

    Surovtsev, E. V. Fomin, I. A.

    2010-08-15

    The magnetic-field dependences of the threshold temperature of the low-temperature instability of uniform spin precession in pure {sup 3}He-B and {sup 3}He-B in an aerogel have been determined for the bulk mechanism. These dependences appear to be different. The theoretical dependence of the threshold temperature for the pure case has been compared with the experimental dependence. The threshold temperature of the instability for {sup 3}He in the aerogel has been estimated for typical experimental conditions.

  18. Spin Diffusion Coefficient of A1-PHASE of Superfluid 3He at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Afzali, R.; Pashaee, F.

    The spin diffusion coefficient tensor of the A1-phase of superfluid 3He at low temperatures and melting pressure is calculated using the Boltzmann equation approach and Pfitzner procedure. Then considering Bogoliubov-normal interaction, we show that the total spin diffusion is proportional to 1/T2, the spin diffusion coefficient of superfluid component D\\uparrowxzxz is proportional to T-2, and the spin diffusion coefficient of super-fluid component D\\uparrowxxxx (=D\\uarrowxyxy) is independent of temperature. Furthermore, it is seen that superfluid components play an important role in spin diffusion of the A1-phase.

  19. Gas cells for 3He hyperpolarized via spin-exchange optical pumping

    NASA Astrophysics Data System (ADS)

    Kim, W.; Stepanyan, S. S.; Kim, A.; Tan, J. A.; Woo, S.

    2016-01-01

    We present a device for the production of hyperpolarized 3He, which is widely used in spinrelated nuclear physics research. Spin-exchange optical pumping (SEOP) is employed to polarize 3He enclosed in a circular borosilicate glass cell suitable not only for the production of polarized gas but also for its storage. The portable glass cell can, thus, be transported to any other research facility. The glass cell can be refilled several times. Special attention is given to the preparation and the filling of the cell to minimize the impurities on its walls and in the gas. We employ glass tubes with shorter lengths and larger diameters in the gas-filling system to achieve the improvement in the air flow necessary to obtain purer polarized 3He samples. The cell is prepared, and after it has been filled with rubidium (Rb) and 3He-N2 mixture, it is sealed under high vacuum conditions. The cell containing the mixture is exposed to circularly-polarized laser light with a wavelength of 795 nm at temperatures of 180 - 220 °C for SEOP. The polarization of 3He is measured via nuclear magnetic resonance (NMR). We obtained 40% polarized 3He in less than 15 hours and 50% in about 25 hours. The longitudinal relaxation time T 1 of the polarized 3He we measured was about 58 hours.

  20. Polarization Induced Spin Wave Damping in Spin Polarized Liquid 3He 4He

    NASA Astrophysics Data System (ADS)

    Perisanu, Sorin; Vermeulen, Gerard

    2007-08-01

    We have measured the temperature and polarization dependence of Silin spin wave spectra in a saturated 3He 4He mixture with a concentration of 9.4% at a pressure of 8 bars. The mixture has been cooled and polarized by a Leiden dilution refrigerator to temperatures in the range 10 15 mK and polarizations as high as 9.2% corresponding to 3.4 times the equilibrium polarization of 2.7% in the external magnetic field of 11.36 T. The analysis takes into account the dipolar interactions and results in the relaxation time τ ⊥ and spin diffusion constant D ⊥ . We find that τ ⊥ and D ⊥ are proportional to 1/(T2+mathcal{A}2T_{a0}2) where T is the temperature, mathcal{A} is the polarization enhancement factor and T a0 is the anisotropy temperature for the mixture at equilibrium in the external field. Our result T a0=3.66±0.14 mK is 30% higher than the theoretical prediction for very dilute mixtures and is evidence for the existence of polarization induced relaxation of transverse spin currents.

  1. Theory of spin-exchange optical pumping of 3He and 129Xe

    NASA Astrophysics Data System (ADS)

    Appelt, S.; Baranga, A. Ben-Amar; Erickson, C. J.; Romalis, M. V.; Young, A. R.; Happer, W.

    1998-08-01

    We present a comprehensive theory of nuclear spin polarization of 3He and 129Xe gases by spin-exchange collisions with optically pumped alkali-metal vapors. The most important physical processes considered are (1) spin-conserving spin-exchange collisions between like or unlike alkali-metal atoms; (2) spin-destroying collisions of the alkali-metal atoms with each other and with buffer-gas atoms; (3) electron-nuclear spin-exchange collisions between alkali-metal atoms and 3He or 129Xe atoms; (4) spin interactions in van der Waals molecules consisting of a Xe atom bound to an alkali-metal atom; (5) optical pumping by laser photons; (6) spatial diffusion. The static magnetic field is assumed to be small enough that the nuclear spin of the alkali-metal atom is well coupled to the electron spin and the total spin is very nearly a good quantum number. Conditions appropriate for the production of large quantities of spin-polarized 3He or 129Xe gas are assumed, namely, atmospheres of gas pressure and nearly complete quenching of the optically excited alkali-metal atoms by collisions with N2 or H2 gas. Some of the more important results of this work are as follows: (1) Most of the pumping and relaxation processes are sudden with respect to the nuclear polarization. Consequently, the steady-state population distribution of alkali-metal atoms is well described by a spin temperature, whether the rate of spin-exchange collisions between alkali-metal atoms is large or small compared to the optical pumping rate or the collisional spin-relaxation rates. (2) The population distributions that characterize the response to sudden changes in the intensity of the pumping light are not described by a spin temperature, except in the limit of very rapid spin exchange. (3) Expressions given for the radio-frequency (rf) resonance linewidths and areas can be used to make reliable estimates of the local spin polarization of the alkali-metal atoms. (4) Diffusion effects for these high

  2. Optical Pumping Spin Exchange {sup 3}He Gas Cells for Magnetic Resonance Imaging

    SciTech Connect

    Kim, W.; Stepanyan, S. S.; Kim, A.; Jung, Y.; Woo, S.; Yurov, M.; Jang, J.

    2009-08-04

    We present a device for spin-exchange optical pumping system to produce large quantities of polarized noble gases for Magnetic Resonance Imaging (MRI). A method and design of apparatus for pumping the polarization of noble gases is described. The method and apparatus enable production, storage and usage of hyperpolarized noble gases for different purposes, including Magnetic Resonance Imaging of human and animal subjects. Magnetic imaging agents breathed into lungs can be observed by the radio waves of the MRI scanner and report back physical and functional information about lung's health and desease. The technique known as spin exchange optical pumping is used. Nuclear magnetic resonance is implemented to measure the polarization of hyperpolarized gas. The cells prepared and sealed under high vacuum after handling Alkali metals into the cell and filling with the {sup 3}He-N{sub 2} mixture. The cells could be refilled. The {sup 3}He reaches around 50% polarization in 5-15 hours.

  3. {sup 3}He Spin-Dependent Cross Sections and Sum Rules

    SciTech Connect

    Slifer, K.; Auerbach, L.; Choi, Seonho; Incerti, S.; Lakuriqi, E.; Meziani, Z.-E.; Amarian, M.; Ketikyan, A.; Voskanian, H.; Averett, T.; Berthot, J.; Bertin, P.; DiSalvo, R.; Fonvieille, H.; Laveissiere, G.; Roblin, Y.

    2008-07-11

    We present a measurement of the spin-dependent cross sections for the {sup 3}He-vector (e-vector,e{sup '})X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1{<=}Q{sup 2}{<=}0.9 GeV{sup 2}. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region.

  4. Pulsed NMR in the nuclear spin ordered phases of solid 3He in a silver sinter

    NASA Astrophysics Data System (ADS)

    Millan-Chacartegui, Carmen; Schuberth, Erwin A.; Deppe, Frank; Schöttl, Stephan

    2003-05-01

    To obtain the exact spin structure of the nuclear magnetically ordered phases of solid 3He, in the BCC lattice called U2D2 and high field phase, both occurring below about 1 mK, we started a project of neutron scattering from the solid at the Hahn-Meitner Institut, Berlin. This experiment faces three main difficulties: to cool the solid to temperatures below 1 mK (or even much lower in the case of the HCP lattice), to keep it there under neutron flux, and to grow a single crystal within the sintered material needed for this purpose. As a first step we have performed pulsed NMR measurements in the ordered phases of solid 3He in a silver sinter of 700 Å particle size down to temperatures of 600 μK at various molar volumes. The samples remained in the ordered state for as long as 110 h.

  5. Double spin asymmetries of inclusive hadron electroproduction from a transversely polarized 3He target

    NASA Astrophysics Data System (ADS)

    Zhao, Y. X.; Allada, K.; Aniol, K.; Annand, J. R. M.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Bradshaw, P. C.; Bosted, P.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J.-P.; Chen, W.; Chirapatpimol, K.; Chudakov, E.; Cisbani, E.; Cornejo, J. C.; Cusanno, F.; Dalton, M.; Deconinck, W.; de Jager, C. W.; De Leo, R.; Deng, X.; Deur, A.; Ding, H.; Dolph, P. A. M.; Dutta, C.; Dutta, D.; El Fassi, L.; Frullani, S.; Gao, H.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Guo, L.; Hamilton, D.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, J.; Huang, M.; Ibrahim, H. F.; Iodice, M.; Jiang, X.; Jin, G.; Jones, M. K.; Katich, J.; Kelleher, A.; Kim, W.; Kolarkar, A.; Korsch, W.; LeRose, J. J.; Li, X.; Li, Y.; Lindgren, R.; Liyanage, N.; Long, E.; Lu, H.-J.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; McNulty, D.; Meziani, Z.-E.; Michaels, R.; Moffit, B.; Muñoz Camacho, C.; Nanda, S.; Narayan, A.; Nelyubin, V.; Norum, B.; Oh, Y.; Osipenko, M.; Parno, D.; Peng, J.-C.; Phillips, S. K.; Posik, M.; Puckett, A. J. R.; Qian, X.; Qiang, Y.; Rakhman, A.; Ransome, R.; Riordan, S.; Saha, A.; Sawatzky, B.; Schulte, E.; Shahinyan, A.; Shabestari, M. H.; Širca, S.; Stepanyan, S.; Subedi, R.; Sulkosky, V.; Tang, L.-G.; Tobias, W. A.; Urciuoli, G. M.; Vilardi, I.; Wang, K.; Wojtsekhowski, B.; Wang, Y.; Yan, X.; Yao, H.; Ye, Y.; Ye, Z.; Yuan, L.; Zhan, X.; Zhang, Y.; Zhang, Y.-W.; Zhao, B.; Zheng, X.; Zhu, L.; Zhu, X.; Zong, X.; Jefferson Lab Hall A Collaboration

    2015-07-01

    We report the measurement of beam-target double spin asymmetries (ALT) in the inclusive production of identified hadrons, e ⃗ + 3He↑→h+X, using a longitudinally polarized 5.9-GeV electron beam and a transversely polarized 3He target. Hadrons (π ±,K±, and proton) were detected at 16° with an average momentum =2.35 GeV/c and a transverse momentum (pT) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the 3He target were observed to be nonzero for π± production when the target was polarized transversely in the horizontal plane. The π+ and π- asymmetries have opposite signs, analogous to the behavior of ALT in semi-inclusive deep-inelastic scattering.

  6. Hybrid K-Rb Spin Exchange Optical Pumping Cells for the Polarization of ^3He

    NASA Astrophysics Data System (ADS)

    Couture, Alex; Daniels, Tim; Arnold, Charles; Clegg, Tom

    2006-11-01

    We are transitioning from polarizing ^3He using optical pumping cells charged with pure Rb to using a mixture of Rb and K, lean in Rb. The reason for this is the spin exchange efficiency between K and ^3He is an order of magnitude greater than that of Rb and ^3He. Also the spin exchange cross section between Rb and K is very large, which leads to a very fast rate of polarization transfer from Rb to K. Thus by optically pumping using a standard 795 nm Rb laser on a hybrid K-Rb cell, we can obtain significant improvements in spin-up time as well as improvements in overall polarization.[1] We produce hybrid pumping cells at TUNL using a filling station consisting of an oven and a turbo pumping station to bake out and pump away any impurities in the cells. The alkali metals are introduced into the pumping cells from a Y-shaped manifold with a separate retort for each alkali. We are able to determine the ratio of K to Rb in the vapor using white light absorption spectroscopy. Light from a halogen light bulb is incident upon the heated cell and enters a spectrometer beyond. We examine the relative sizes of the D1 and D2 absorption lines for the two alkali metals. We will have data comparing hybrid cells to pure Rb cells, GE-180 cells to Pyrex, and are working to obtain comparative performance data for spectrally unnarrowed and narrowed lasers. Our latest results will be reported. [1] E. Babcock, et al. (2003) Phys. Rev. Letter Vol. 91, Num.12, 123003

  7. Supersymmetric dark matter search via spin-dependent interaction with 3He

    NASA Astrophysics Data System (ADS)

    Moulin, E.; Mayet, F.; Santos, D.

    2005-05-01

    The potentialities of MIMAC-He3, a MIcro-tpc MAtrix of Chambers of Helium-3, for supersymmetric dark matter search are discussed within the framework of effective MSSM models without gaugino mass unification at the GUT scale. A phenomenological study has been done to investigate the sensitivity of the MIMAC-He3 detector to neutralinos (M≳6GeV/c) via spin-dependent interaction with 3He as well as its complementarity to direct and indirect detection experiments. Comparison with other direct dark matter searches will be presented in a WIMP model-independent framework.

  8. Spin-polarized /sup 3/He nuclear targets and metastable /sup 4/He atoms by optical pumping with a tunable, Nd:YAP laser

    SciTech Connect

    Bohler, C.L.; Schearer, L.D.; Leduc, M.; Nacher, P.J.; Zachorowski, L.; Milner, R.G.; McKeown, R.D.; Woodward, C.E.

    1988-04-15

    Several Nd:YAP lasers were constructed which could be broadly tuned in the 1083-nm region which includes the helium 2/sup 3/S-2/sup 3/P transition, using a Lyot filter and thin, uncoated etalons within the laser cavity. 1 W of power could be extracted at 1083 nm through a 1% transmitting output coupler. This laser beam was used to optically pump metastable /sup 4/He and /sup 3/He 2/sup 3/S helium atoms in a weak discharge cell, spin polarizing the metastable ensemble. In a /sup 3/He cell the polarization is transferred to the nuclear spin system. A /sup 3/He target cell at 0.3 Torr was polarized to 52% in a few minutes. We describe the application of this system to the design of polarized targets for experiments in nuclear physics.

  9. Precision Measurement of the Spin-dependent Asymmetry in the Threshold Region of Quasielastic 3He

    SciTech Connect

    Feng Xiong

    2002-09-01

    The first precision measurement of the spin-dependent asymmetry in the threshold region of polarized {sup 3}He(polarized e, e') was carried out in Hall A at the Jefferson Laboratory, using a longitudinally polarized continuous electron beam incident on a high-pressure polarized {sup 3}He gas target. The polarized electron beam was generated by illuminating a strained GaAs cathode with high intensity circularly polarized laser light, and an average beam polarization of about 70% was achieved. The {sup 3}He target was polarized based on the principle of spin-exchange optical pumpint and the average target polarization was about 30%. The scattered electrons were detected in the two Hall A high resolution spectrometers, HRSe and HRSh. The data from HRSh were used for this analysis and covered both the elastic peak and the threshold region. Two kinematic points were measured in the threshold region, one with a central Q{sup 2}-value of 0.1 (GeV/c){sup 2} at an incident beam energy E{sub 0} = 0.778 GeV and the other with a central Q{sup 2}-value of 0.2 (GeV/c){sup 2} at E-0 = 1.727 GeV. The average beam current was 10 mu-A, which was mainly due to the limitation of the polarized {sup 3}He target. The measured asymmetry was compared with both plane wave impulse approximation (PWIA) calculations and non-relativistic full Faddeev calculations which include both final-state interactions (FSIs) and meson-exchange currents (MECs) effects. The poor description of the data by PWIA calculations at both Q{sup 2}-values suggests the existence of strong FSI and MEC effects in the threshold region of polarized {sup 3}He (polarized e, e'). Indeed, the agreement between the data and full calculations is very good at Q{sup 2} = 0.1 (GeV/c){sup 2}. On the other hand, a small discrepancy at Q{sup 2} = 0.2 (GeV/c){sup 2} is observed, which might be due to some Q{sup 2} -dependent effects such as relativity and three-nucleon forces (3NFs), which are not included in the framework of non

  10. Magnetization studies of the nuclear spin ordered phases of solid 3He in silver sinters

    NASA Astrophysics Data System (ADS)

    Schuberth, E. A.; Kath, M.; Tassini, L.; Millan-Chacartegui, C.

    2005-08-01

    Solid 3He, in the bcc lattice between 34 and 100 bar, exhibits two nuclear magnetic ordered phases in the sub-mK temperature range, the so called U2D2 low (magnetic) field phase and the “high field phase” above 0.4 T. To determine the exact spin structure of these phases we started a project of neutron scattering from the ordered solid in collaboration with the Hahn-Meitner Institute, Berlin, and other European and US groups. For this experiment it is crucial to grow a single crystal within the sinter needed for cooling the solid to temperatures of the order of 500 μK (or even twenty times lower in the case of the hcp lattice which is formed above 100 bar) and to keep it there long enough to measure a magnetic neutron reflection. We studied the growth of crystals in Ag sinters of different pore size and with different growth speeds to find an optimal way to obtain single crystalline samples. As a first diagnostic step we performed pulsed NMR measurements in the ordered phases of solid 3He in a sinter of 2700 Å particle size down to temperatures of 450 μK at various molar volumes. We could keep the samples in the ordered state for as long as 140 h. The second method we used was SQUID magnetometry. For the low field phase TN was indicated by a drop of the intensity, both in the NMR signal and in the dc magnetization, whereas in the high field phase an increase of about 30% was observed below the ordering temperature. For the fabrication of the sinters a packing fraction of 50% and subsequent annealing proved to be very favorable to obtain cold ordered solid. Furthermore, we find that a paramagnetic surface contribution from a few monolayers of 3He exists down to 500 μK in addition to the bulk magnetization.

  11. Detecting the Majorana fermion surface state of ^3He-B through spin relaxation

    NASA Astrophysics Data System (ADS)

    Chung, Suk Bum; Zhang, Shoucheng

    2010-03-01

    The concept of the Majorana fermion has been postulated more than eighty years ago; however, this elusive particle has never been observed in nature. The non-local character of the Majorana fermion can be useful for topological quantum computation. Recently, it has been shown that the 3He-B phase is a time-reversal invariant topological superfluid, with a single component of gapless Majorana fermion state localized on the surface. Such a Majorana surface state contains half the degrees of freedom of the single Dirac surface state recently observed in topological insulators. We show here that the Majorana surface state can be detected through an electron spin relaxation experiment. The Majorana nature of the surface state can be revealed though the striking angular dependence of the relaxation time on the magnetic field direction, 1/T1sin^2 θ where θ is the angle between the magnetic field and the surface normal. The temperature dependence of the spin relaxation rate can reveal the gapless linear dispersion of the Majorana surface state. We propose a spin relaxation experiment setup where we inject an electron inside a nano- sized bubble below the helium liquid surface.

  12. Limit on Lorentz-Invariance- and CPT-Violating Neutron Spin Interactions Using a 3He-129Xe Comagnetometer

    NASA Astrophysics Data System (ADS)

    Allmendinger, F.; Schmidt, U.; Heil, W.; Karpuk, S.; Sobolev, Yu.; Tullney, K.

    2016-02-01

    We performed a search for a Lorentz-invariance- and CPT-violating coupling of the 3He and 129Xe nuclear spins to posited background fields. Our experimental approach is to measure the free precession of nuclear spin polarized 3He and 129Xe atoms using SQUIDs as detectors. As the laboratory reference frame rotates with respect to distant stars, we look for a sidereal modulation of the Larmor frequencies of the co-located spin samples. As a result we obtain an upper limit on the equatorial component of the background field b˜⊥n < 8.4 ṡ 10‑34 GeV (68% C.L.). This experiment is currently the most precise test of spin anisotropy due to the excellent long spin-coherence time.

  13. Study of neutron spin structure functions at low Q{sup 2} with polarized {sup 3}He

    SciTech Connect

    Seonho Choi

    2000-12-12

    The recently completed experiment E94-010 at Jefferson Lab studies the neutron spin structure functions at low momentum transfer (Q{sup 2}) values. Using a polarized {sup 3} He target and polarized electron beam, we have measured the asymmetries and cross sections for {sup 3}He(e,e') from the elastic to the deep inelastic region. The covered Q{sup 2} ranges from 0.03 to 1.1 GeV{sup 2}. From the data, the Q{sup 2} evolution of the spin structure functions for {sup 3}He and neutron, and of the Gerasimov-Drell-Hearn (GDH) sum rule has been studied, and the preliminary results are presented.

  14. Spin assignments to excited states in 22Na through a 24Mg(p,3He)22Na reaction measurement

    SciTech Connect

    Chae, K. Y.; Bardayan, Daniel W; Blackmon, Jeff C; Chipps, K.; Hatarik, Robert; Jones, K. L.; Kozub, R. L.; Liang, J Felix; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Pain, S. D.; Pittman, S. T.; Smith, Michael Scott

    2010-10-01

    The level structure of 22Na has been studied at the Holifield Radioactive Ion Beam Facility in Oak Ridge National Laboratory using the 24Mg(p,3He)22Na reaction. 41 and 41.5 MeV proton beams were generated by 25 MV tandem accelerator and bombarded isotopically enriched 24Mg targets. Angular distributions of recoiling 3He particles were extracted by using a segmented annular silicon strip detector array. Spins and parities for ten levels were constrained through a distorted wave Born approximation analysis of angular distributions including three above the proton threshold at 6.739 MeV.

  15. Spin exchange optical pumping based polarized {sup 3}He filling station for the Hybrid Spectrometer at the Spallation Neutron Source

    SciTech Connect

    Jiang, C. Y.; Tong, X.; Brown, D. R.; Culbertson, H.; Kadron, B.; Robertson, J. L.; Graves-Brook, M. K.; Hagen, M. E.; Lee, W. T.; Winn, B.

    2013-06-15

    The Hybrid Spectrometer (HYSPEC) is a new direct geometry spectrometer at the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is equipped with polarization analysis capability with 60 Degree-Sign horizontal and 15 Degree-Sign vertical detector coverages. In order to provide wide angle polarization analysis for this instrument, we have designed and built a novel polarized {sup 3}He filling station based on the spin exchange optical pumping method. It is designed to supply polarized {sup 3}He gas to HYSPEC as a neutron polarization analyzer. In addition, the station can optimize the {sup 3}He pressure with respect to the scattered neutron energies. The depolarized {sup 3}He gas in the analyzer can be transferred back to the station to be repolarized. We have constructed the prototype filling station. Preliminary tests have been carried out demonstrating the feasibility of the filling station. Here, we report on the design, construction, and the preliminary results of the prototype filling station.

  16. Search for Spin-Dependent Short-Range Interaction with an 3He/129Xe Clock Comparison Experiment

    NASA Astrophysics Data System (ADS)

    Tullney, Kathlynne; Heil, Werner; Karpuk, Sergei; Sobolev, Yuri; Allmendinger, Fabian; Schmidt, Ulrich

    2016-02-01

    We performed an experiment to search for a new spin-dependent P- and T-violating nucleon-nucleon interaction σ→ ṡr̂ which is mediated by light pseudoscalar bosons such as axions or axionlike particles. This interaction causes a shift Δν in the precession frequency of nuclear spin polarized gases in the presence of an unpolarized mass. In order to measure this frequency shift a 3He/129Xe comagnetometer was used which is based on the detection of free precession of 3He and 129Xe nuclear spins using SQUIDs as detectors. For the upper limit of Δνsp we obtained 7.1nHz. With this value, an upper limit of the scalar-pseudoscalar coupling of the axion to the spin of a bound neutron could be deduced within the axion mass window. For axion masses between 2 and 500μeV, the laboratory upper bounds were improved by up to 4 orders of magnitude.

  17. The Spin Structure of 3He and the Neutron at Low Q^2: A Measurement of the Generalized GDH Integrand

    SciTech Connect

    Sulkosky, Vincent

    2007-08-01

    Since the 1980's, the study of nucleon (proton or neutron) spin structure has been an active field both experimentally and theoretically. One of the primary goals of this work is to test our understanding of Quantum Chromodynamics (QCD), the fundamental theory of the strong interaction. In the high energy region of asymptotically free quarks, QCD has been verified. However, verifiable predictions in the low energy region are harder to obtain due to the complex interactions between the nucleon's constituents: quarks and gluons. In the non-pertubative regime, low-energy effective field theories such as chiral perturbation theory provide predictions for the spin structure functions in the form of sum rules. Spin-dependent sum rules such as the Gerasimov-Drell-Hearn (GDH) sum rule are important tools available to study nucleon spin structure. Originally derived for real photon absorption, the Gerasimov-Drell-Hearn (GDH) sum rule was first extended for virtual photon absorption in 1989. The extension of the sum rule provides a unique relation, valid at any momentum transfer ($Q^{2}$), that can be used to study the nucleon spin structure and make comparisons between theoretical predictions and experimental data. Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) to examine the spin structure of the neutron and $^{3}$He. The Jefferson Lab longitudinally-polarized electron beam with incident energies between 1.1 and 4.4 GeV was scattered from a longitudinally or transversely polarized $^{3}$He gas target in the Hall A end station. Asymmetries and polarized cross-section differences were measured in the quasielastic and resonance regions to extract the spin structure functions $g_{1}(x,Q^{2})$ and $g_{2}(x,Q^{2})$ at low momentum transfers (0.02 $< Q^{2} <$ 0.3 GeV$^{2}$). The goal of the experiment was to perform a precise measurement of the $Q^{2}$ dependence of the extended GDH integral and of the moments of the neutron

  18. Precision Measurement of the Spin Dependent Asymmetry in the Threshold Region of {sup 3}He(e,e{prime})

    SciTech Connect

    F. Xiong; Dipangkar Dutta; W. Xu; Bryon Anderson; L. Auberbach; Todd Averett; William Bertozzi; Timothy Black; John Calarco; Larry Cardman; Gorden Cates; Zhengwei Chai; Jian-ping Chen; Seonho Choi; Eugene Chudakov; Steve Churchwell; G.S. Corrado; C. Crawford; Dan Dale; Alexandre Deur; Pibaro Djawotho; Bradley Filippone; Mike Finn; Haiyan Gao; Ron Gilman; Alexander Glamazdin; Charles Glashausser; W. Glockle; J. Golak; Javier Gomez; Victor Gorbenko; Jens-Ole Hansen; F. William Hersman; Douglas W. Higinbotham; Richard Holmes; C.R. Howell; E. Hughes; B. Humensky; Sebastian Incerti; Kees de Jager; J.Steffen Jensen; Xiangdong Jiang; C.E. Jones; Mark Jones; R. Kahl; H. Kamada; A. Kievsky; Ioannis Kominis; Wolfgang Korsch; Kevin Kramer; Gerfried Kumbartzki; Michael Kuss; E. Lakuriqi; Meme Liang; Nilanga Liyanage; John LeRose; Sergey Malov; Dimitri Margaziotis; Jeffrey Martin; Kathy McCormick; Robert McKeown; K. McIlhany; Zein-Eddine Meziani; Robert Michaels; G.W. Miller; E. Pace; T. Pavlin; Gerassimos G. Petratos; R.I. Pomatsalyuk; D. Pripstein; David Prout; Ronald Ransome; Yves Roblin; Marat Rvachev; Arun Saha; G. Salme; M. Schnee; Taeksu Shin; Karl Slifer; Paul Souder; Steffen Strauch; Riad Suleiman; M. Sutter; Bryan Tipton; Luminita Todor; M. Viviani; B. Vlahovic; J. Watson; C.F. Williamson; H. Witala; Bogdan B. Wojtsekhowski; J. Yeh; P. Zolnierczuk

    2001-12-10

    We present the first precision measurement of the spin-dependent asymmetry in the threshold region of {sup 3}He(e,e{prime}) at Q{sup 2}-values of 0.1 and 0.2 (GeV/c){sup 2}. The agreement between the data and non-relativistic Faddeev calculations which include both final-state interactions (FSI) and meson-exchange currents (MEC) effects is very good at Q{sup 2} = 0.1 (GeV/c){sup 2}, while a small discrepancy at Q{sup 2} = 0.2 (GeV/c){sup 2} is observed.

  19. Single spin asymmetries of inclusive hadrons produced in electron scattering from a transversely polarized 3He target

    NASA Astrophysics Data System (ADS)

    Allada, K.; Zhao, Y. X.; Aniol, K.; Annand, J. R. M.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Bradshaw, P. C.; Bosted, P.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J.-P.; Chen, W.; Chirapatpimol, K.; Chudakov, E.; Cisbani, E.; Cornejo, J. C.; Cusanno, F.; Dalton, M.; Deconinck, W.; de Jager, C. W.; De Leo, R.; Deng, X.; Deur, A.; Ding, H.; Dolph, P. A. M.; Dutta, C.; Dutta, D.; Fassi, L. El; Frullani, S.; Gao, H.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Guo, L.; Hamilton, D.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, J.; Huang, M.; Ibrahim, H. F.; Iodice, M.; Jiang, X.; Jin, G.; Jones, M. K.; Katich, J.; Kelleher, A.; Kim, W.; Kolarkar, A.; Korsch, W.; LeRose, J. J.; Li, X.; Li, Y.; Lindgren, R.; Liyanage, N.; Long, E.; Lu, H.-J.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; McNulty, D.; Meziani, Z.-E.; Michaels, R.; Moffit, B.; Camacho, C. Muñoz; Nanda, S.; Narayan, A.; Nelyubin, V.; Norum, B.; Oh, Y.; Osipenko, M.; Parno, D.; Peng, J.-C.; Phillips, S. K.; Posik, M.; Puckett, A. J. R.; Qian, X.; Qiang, Y.; Rakhman, A.; Ransome, R.; Riordan, S.; Saha, A.; Sawatzky, B.; Schulte, E.; Shahinyan, A.; Shabestari, M. H.; Širca, S.; Stepanyan, S.; Subedi, R.; Sulkosky, V.; Tang, L.-G.; Tobias, A.; Urciuoli, G. M.; Vilardi, I.; Wang, K.; Wang, Y.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Ye, Y.; Ye, Z.; Yuan, L.; Zhan, X.; Zhang, Y.; Zhang, Y.-W.; Zhao, B.; Zheng, X.; Zhu, L.; Zhu, X.; Zong, X.; Jefferson Lab Hall A Collaboration

    2014-04-01

    We report the first measurement of target single spin asymmetries (AN) in the inclusive hadron production reaction, e +3He↑→h+X, using a transversely polarized 3He target. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons (π±, K±, and proton) were detected in the transverse hadron momentum range 0.54 3He target and extracted for neutrons are opposite in sign with a small increase observed as a function of pT.

  20. Single spin asymmetries of inclusive hadrons produced in electron scattering from a transversely polarized 3 He target

    DOE PAGESBeta

    Allada, K.; Zhao, Y. X.; Aniol, K.; Annand, J. R. M.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Bradshaw, P. C.; Bosted, P.; Camsonne, A.; et al

    2014-04-07

    We report the first measurement of target single-spin asymmetries (AN) in the inclusive hadron production reaction, e + 3He↑→h+X, using a transversely polarized 3 He target. This experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons (π±, K± and proton) were detected in the transverse hadron momentum range 0.54 < pT < 0.74 GeV/c. The range of xF for pions was -0.29 < xF< -0.23 and for kaons -0.25 < xF<-0.18. The observed asymmetry strongly depends on the type of hadron. A positive asymmetry is observed for π+ and K+. Amore » negative asymmetry is observed for π–. The magnitudes of the asymmetries follow |Aπ –|<|Aπ +|<|AK +|. The K– and proton asymmetries are consistent with zero within the experimental uncertainties. The π+ and π– asymmetries measured for the 3He target and extracted for neutrons are opposite in sign with a small increase observed as a function of pT.« less

  1. Distorted spin dependent spectral function of {sup 3}He and semi-inclusive deep inelastic scattering processes

    SciTech Connect

    Kaptari, Leonya P.; Del Dotto, Alessio; Pace, Emanuele; Salme, Giovanni; Scopetta, Sergio

    2014-03-01

    The spin dependent spectral function, relevant to describe polarized electron scattering off polarized {sup 3}He, is studied, within the Plane Wave Impulse Approximation and taking into account final state interaction effects (FSI). In particular, the case of semi-inclusive deep inelastic scattering (SiDIS) is considered, evaluating the FSI of the hadronizing quark with the nuclear remnants. It is shown that particular kinematical regions can be selected to minimize the latter effects, so that parton distributions in the neutron can be accessed. On the other side, in the regions where FSI dominates, the considered reactions can elucidate the mechanism of hadronization of quarks during the propagation in the nuclear medium. It is shown that the obtained spin dependent spectral function can be directly applied to investigate the SiDIS reaction e-vector + {sup 3}He-vector to h+X, where the hadron h originates from the current fragmentation. Experiments of this type are being performed at JLab to extract neutron transverse momentum dependent parton distributions. As a case study, a different SiDIS process, with detection of slow (A-1) systems in the final state, is considered in more details, in order to establish when nuclear structure effects and FSI can be distinguished from elementary reactions on quasi-free nucleons. It is argued that, by a proper choice of kinematics, the origin of nuclear effects in polarized DIS phenomena and the details of the interaction between the hadronizing quark and the nuclear medium can be investigated at a level which is not reachable in inclusive deep inelastic scattering.

  2. Online SEOP polarization of Large Area Neutron Spin Filters

    NASA Astrophysics Data System (ADS)

    Babcock, Earl; Salhi, Zahir; Ioffe, Alexander

    2015-04-01

    The Juelich Center for neutron Science has a program to use SEOP polarized 3He Neutron Spin Filters (3He NSF) on many neutron scattering instruments. The main applications are for polarization analysis of the scattered beam. As such, the devices must operate in close proximity to the neutron sample and sample environment which can include complicated cryostats, humidity and pressure cells, and high field magnets. Thus we have developed novel magnetic cavities to house the 3He NSF cells which allow for simultaneous optical pumping on the instruments. Further we continually develop and redevelop the laser sources which must be relatively narrow band and have long term (i.e. months) stability and robust operation. The first fully operational polarizer has been used continuously for over 2, 60-day reactor cycles at the FRM2. This device uses a 12.5 cm I.D. 3He cell, and has a 3He storage lifetime, including the cells lifetime, in excess of 200 hours with the cell about 60 cm from the sample position inside a 1.2 T electromagnet, and has achieved over 75% 3He polarisation when fully optimized. This talk will describe the magnetic cavities, and laser sources as well as provide a description of the completed 3He polarizer devices.

  3. Non-spin-flip ( 3He, t) charge-exchange and isobaric analog states of actinide nuclei studied at θ = 0°, E( 3He) = 76 MeV and 200 MeV

    NASA Astrophysics Data System (ADS)

    Jänecke, J.; Becchetti, F. D.; van den Berg, A. M.; Berg, G. P. A.; Brouwer, G.; Greenfield, M. B.; Harakeh, M. N.; Hofstee, M. A.; Nadasen, A.; Roberts, D. A.; Sawafta, R.; Schippers, J. M.; Stephenson, E. J.; Stewart, D. P.; van der Werf, S. Y.

    1991-04-01

    The ( 3He, t) charge-exchange reaction has been studied at θ = 0° and bombarding energies of E( 3He) = 76.5 MeV and 200 MeV. Spectra were measured using magnetic analysis for target nuclei of 12, 13C, 16O, 19F, 28, 29, 30Si, 90Zr, 117, 120Sn, natTa, natW, 197Au, 208Pb, 230, 232Th, 234, 236, 238U and 244Pu. The measurements at 76.5 MeV concentrated on the isobaric analog states of several actinide nuclei, particularly on their widths and the branching ratios for proton decay. Cross sections, Q-values and total widths were determined for the transitions to the isobaric analog states. Coulomb displacement energies derived from the measured Q-values display the influence of deformed nuclear shapes. Escape widths Γ ↑ and spreading widths Γ ↓ of the isobaric analog states in five actinide nuclei were deduced from the measured proton-decay branching ratios. They were found to be in agreement with predictions which postulate isospin mixing via the Coulomb force with the ( T0-1)-component of the isovector giant monopole resonance. The measurements at 200 MeV were concerned with transitions to isobaric analog states in both light and heavy nuclei, including several actinide nuclei, but Gamow-Teller resonances and transitions to numerous other states were also observed. The measured cross sections for several transitions to isobaric analog states from 30Si to 208Pb were used to extract the effective interaction Vτ for non-spin-flip ( 3He, t) charge exchange at E( 3He) ≈ 200 MeV. The interaction strength Vτ decreases by a factor 0.6 when compared to previously measured values for the energy range E( 3He) = 65 to 90 MeV. An angular distribution from θτ = 0° to 16° for the transition to the isobaric analog state in 120Sb measured at E( 3He) = 200 MeV was found to be in very good agreement with microscopic calculations.

  4. Neutron Polarizers Based on Polarized 3He

    SciTech Connect

    William M. Snow

    2005-05-01

    The goal of this work, which is a collaborative effort between Indiana University, NIST, and Hamilton College, is to extend the technique of polarized neutron scattering into new domains by the development and application of polarized 3He-based neutron spin filters. After the IPNS experiment which measured Zeeman sp[litting in surface scattered neutrons using a polarized 3He cell as a polarization analyzer transporterd by car from Bloomington to Chicago, the Indiana work focused on technical developments to improve the 3He polarization of the Indiana compression system. The compression system was rebuilt with a new valve system which allows gas trapped in the dead volume of the compressors at the end of the piston stroke to be exhausted and conducted back to the optical pumping cell where it can be repolarized. We also incorporated a new intermediate storage volume made at NIST from 1720 glass which will reduce polarization losses between the compressors. Furthermore, we improved the stability of the 1083 nm laser by cooling the LMA rod. We achieved 60% 3he polarization in the optical pumping cell and 87% preservation of the polarization during compression. In parallel we built a magnetically-shielded transport solenoid for use on neutron scattering instruments such as POSY which achieves a fractional field uniformity of better than 10-3 per cm. The field was mapped using an automated 3D field mapping system for in-situ measurement of magnetic field gradients Diluted magnetic semiconductors offer many exciting opportunities for investigation of spintronic effects in solids and are certain to be one of the most active areas of condensed matter physics over then next several years. These materials can act as efficient spin injectors for devices that make use of spin-dependent transport phenomena. We just (late July 2002) finished a neutron reflectivity experiment at NIST on a GaMnAs trilayer film. This material is a ferromagnetic semiconductor which is of interest

  5. Two Wien Filter Spin Flipper

    SciTech Connect

    Grames, J M; Benesch, J F; Clark, J; Hansknecht, J; Kazimi, R; Machie, D; Poelker, M; Stutzman, M L; Suleiman, R; Zhang, Y

    2011-03-01

    A new 4pi spin manipulator composed of two Wien filters oriented orthogonally and separated by two solenoids has been installed at the CEBAF/Jefferson Lab photoinjector. The new spin manipulator is used to precisely set the electron spin direction at an experiment in any direction (in or out of plane of the accelerator) and provides the means to reverse, or flip, the helicity of the electron beam on a daily basis. This reversal is being employed to suppress systematic false asymmetries that can jeopardize challenging parity violation experiments that strive to measure increasingly small physics asymmetries [*,**,***]. The spin manipulator is part of the ultra-high vacuum polarized electron source beam line and has been successfully operated with 100keV and 130keV electron beam at high current (>100 microAmps). A unique feature of the device is that spin-flipping requires only the polarity of one solenoid magnet be changed. Performance characteristics of the Two Wien Filter Spin Flipper will be summarized.

  6. A compact spin-exchange optical pumping system for 3He polarization based on a solenoid coil, a VBG laser diode, and a cosine theta RF coil

    NASA Astrophysics Data System (ADS)

    Lee, Sungman; Kim, Jongyul; Moon, Myung Kook; Lee, Kye Hong; Lee, Seung Wook; Ino, Takashi; Skoy, Vadim R.; Lee, Manwoo; Kim, Guinyun

    2013-02-01

    For use as a neutron spin polarizer or analyzer in the neutron beam lines of the HANARO (High-flux Advanced Neutron Application ReactOr) nuclear research reactor, a 3He polarizer was designed based on both a compact solenoid coil and a VBG (volume Bragg grating) diode laser with a narrow spectral linewidth of 25 GHz. The nuclear magnetic resonance (NMR) signal was measured and analyzed using both a built-in cosine radio-frequency (RF) coil and a pick-up coil. Using a neutron transmission measurement, we estimated the polarization ratio of the 3He cell as 18% for an optical pumping time of 8 hours.

  7. In-situ compact 3He neutron spin polarizer based on a magneto-static cavity with built-in NMR coils

    NASA Astrophysics Data System (ADS)

    Lee, S.; Moon, M. K.; Kim, J.; Cho, S. J.; Lee, J. H.; Lee, C.-H.; Lee, S. W.; Ino, T.

    2016-04-01

    A polarized 3He neutron polarizer for in-situ neutron beam line operation was developed based on a compact magneto-static cavity with a dimension of 280×270×300 mm3 and a fiber-coupled VBG (Volume Bragg Grating) diode laser with a narrow spectral bandwidth of 25 GHz. Built-in NMR coils of the neutron spin polarizer designed for NMR signal measurements were described in detail and their performances were tested for monitoring the progress of in-situ 3He polarization.

  8. Photonic spin filter with dielectric metasurfaces.

    PubMed

    Ke, Yougang; Liu, Yachao; Zhou, Junxiao; Liu, Yuanyuan; Luo, Hailu; Wen, Shuangchun

    2015-12-28

    We propose a photonic spin filter whose structure is similar to that of conventional spatial filter, but the two plano-convex lenses are replaced by Pancharatnam-Berry phase ones. The dielectric metasurface with high transmission and conversion efficiency is designed to work as Pancharatnam-Berry phase lens. The photonic spin filter can sort desired spin photons from the input beam with mixed spin states, and thereby facilitate possible applications in spin-based photonics. PMID:26831976

  9. Spin-filtering at COSY

    NASA Astrophysics Data System (ADS)

    Weidemann, Christian; PAX Collaboration

    2011-05-01

    The Spin Filtering experiments at COSY and AD at CERN within the framework of the Polarized Antiproton EXperiments (PAX) are proposed to determine the spin-dependent cross sections in bar pp scattering by observation of the buildup of polarization of an initially unpolarized stored antiproton beam after multiple passage through an internal polarized gas target. In order to commission the experimental setup for the AD and to understand the relevant machine parameters spin-filtering will first be done with protons at COSY. A first major step toward this goal has been achieved with the installation of the required mini-β section in summer 2009 and it's commissioning in January 2010. The target chamber together with the atomic beam source and the so-called Breit-Rabi polarimeter have been installed and commissioned in summer 2010. In addition an openable storage cell has been used. It provides a target thickness of 5·1013 atoms/cm2. We report on the status of spin-filtering experiments at COSY and the outcome of a recent beam time including studies on beam lifetime limitations like intra-beam scattering and the electron-cooling performance as well as machine acceptance studies.

  10. Meaurement of the target single-spin asymmetry in quasi-elastic region from the reaction {sup 3}He{up_arrow}(e,e')

    SciTech Connect

    Zhang, Yawei

    2013-10-01

    A measurement of the inclusive target single-spin asymmetry has been performed using the quasi-elastic {sup 3}He{up_arrow}(e,e') reaction with a vertically polarized {sup 3}He target at Q{sup 2} values of 0.13, 0.46 and 0.97 GeV{sup 2}. This asymmetry vanishes under the one photon exchange assumption. But the interference between two-photon exchange and one-photon exchange gives rise to an imaginary amplitude, so that a non-zero A{sub y} is allowed. The experiment, conducted in Hall A of Jefferson Laboratory in 2009, used two independent spectrometers to simultaneously measure the target single-spin asymmetry. Using the effective polarization approximation, the neutron single-spin asymmetries were extracted from the measured {sup 3}He asymmetries. The measurement is to establish a non-vanishing A{sub y}. Non-zero asymmetries were observed at all Q{sup 2} points, and the overall precision is an order of magnitude improved over the existing proton data. The data provide new constraints on Generalized Parton Distribution (GPD) models and new information on the dynamics of the two-photon exchange process.

  11. Measurement of the Target-Normal Single-Spin Asymmetry in Quasielastic Scattering from the Reaction (3)He(↑)(e,e').

    PubMed

    Zhang, Y-W; Long, E; Mihovilovič, M; Jin, G; Allada, K; Anderson, B; Annand, J R M; Averett, T; Ayerbe-Gayoso, C; Boeglin, W; Bradshaw, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J P; Chudakov, E; De Leo, R; Deng, X; Deur, A; Dutta, C; El Fassi, L; Flay, D; Frullani, S; Garibaldi, F; Gao, H; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, J; Ibrahim, H; de Jager, C W; Jensen, E; Jiang, X; St John, J; Jones, M; Kang, H; Katich, J; Khanal, H P; King, P; Korsch, W; LeRose, J; Lindgren, R; Lu, H-J; Luo, W; Markowitz, P; Meziane, M; Michaels, R; Moffit, B; Monaghan, P; Muangma, N; Nanda, S; Norum, B E; Pan, K; Parno, D; Piasetzky, E; Posik, M; Punjabi, V; Puckett, A J R; Qian, X; Qiang, Y; Qiu, X; Riordan, S; Ron, G; Saha, A; Sawatzky, B; Schiavilla, R; Schoenrock, B; Shabestari, M; Shahinyan, A; Širca, S; Subedi, R; Sulkosky, V; Tobias, W A; Tireman, W; Urciuoli, G M; Wang, D; Wang, K; Wang, Y; Watson, J; Wojtsekhowski, B; Ye, Z; Zhan, X; Zhang, Y; Zheng, X; Zhao, B; Zhu, L

    2015-10-23

    We report the first measurement of the target single-spin asymmetry, A(y), in quasielastic scattering from the inclusive reaction (3)He(↑)(e,e') on a (3)He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A nonzero A(y) can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the substructure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q(2)=0.13, 0.46, and 0.97  GeV(2). These measurements demonstrate, for the first time, that the (3)He asymmetry is clearly nonzero and negative at the 4σ-9σ level. Using measured proton-to-(3)He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q(2) is related to moments of the generalized parton distributions (GPDs). Our measured neutron asymmetry at Q(2)=0.97  GeV(2) agrees well with a prediction based on two-photon exchange using a GPD model and thus provides a new, independent constraint on these distributions. PMID:26551107

  12. Measurement of the Target-Normal Single-Spin Asymmetry in Quasielastic Scattering from the Reaction 3He ↑(e ,e' )

    NASA Astrophysics Data System (ADS)

    Zhang, Y.-W.; Long, E.; Mihovilovič, M.; Jin, G.; Allada, K.; Anderson, B.; Annand, J. R. M.; Averett, T.; Ayerbe-Gayoso, C.; Boeglin, W.; Bradshaw, P.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J. P.; Chudakov, E.; De Leo, R.; Deng, X.; Deur, A.; Dutta, C.; El Fassi, L.; Flay, D.; Frullani, S.; Garibaldi, F.; Gao, H.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Gomez, J.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, J.; Ibrahim, H.; de Jager, C. W.; Jensen, E.; Jiang, X.; John, J. St.; Jones, M.; Kang, H.; Katich, J.; Khanal, H. P.; King, P.; Korsch, W.; LeRose, J.; Lindgren, R.; Lu, H.-J.; Luo, W.; Markowitz, P.; Meziane, M.; Michaels, R.; Moffit, B.; Monaghan, P.; Muangma, N.; Nanda, S.; Norum, B. E.; Pan, K.; Parno, D.; Piasetzky, E.; Posik, M.; Punjabi, V.; Puckett, A. J. R.; Qian, X.; Qiang, Y.; Qiu, X.; Riordan, S.; Ron, G.; Saha, A.; Sawatzky, B.; Schiavilla, R.; Schoenrock, B.; Shabestari, M.; Shahinyan, A.; Širca, S.; Subedi, R.; Sulkosky, V.; Tobias, W. A.; Tireman, W.; Urciuoli, G. M.; Wang, D.; Wang, K.; Wang, Y.; Watson, J.; Wojtsekhowski, B.; Ye, Z.; Zhan, X.; Zhang, Y.; Zheng, X.; Zhao, B.; Zhu, L.; Jefferson Lab Hall A Collaboration

    2015-10-01

    We report the first measurement of the target single-spin asymmetry, Ay, in quasielastic scattering from the inclusive reaction 3He ↑(e ,e' ) on a 3He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A nonzero Ay can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the substructure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q2=0.13 , 0.46, and 0.97 GeV2 . These measurements demonstrate, for the first time, that the 3He asymmetry is clearly nonzero and negative at the 4 σ - 9 σ level. Using measured proton-to-3He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1 - 3 )% were obtained. The neutron asymmetry at high Q2 is related to moments of the generalized parton distributions (GPDs). Our measured neutron asymmetry at Q2=0.97 GeV2 agrees well with a prediction based on two-photon exchange using a GPD model and thus provides a new, independent constraint on these distributions.

  13. Measurement of the Neutron (3He) Spin Structure at Low Q2 and the Extended Gerasimov-Drell-Hearn Sum Rule

    SciTech Connect

    Kominis, Ioannis

    2001-01-31

    This thesis presents the results of E-94010, an experiment at Thomas Jefferson National Accelerator Facility (TJNAF) designed to study the spin structure of the neutron at low momentum transfer, and to test the “extended” Gerasimov-Drell-Hearn (GDH) sum rule. The first experiment of its kind, it was performed in experimental Hall-A of TJNAF using a new polarized 3He facility. It has recently been shown that the GDH sum rule and the Bjorken sum rule are both special examples of a more general sum rule that applies to polarized electron scattering off nucleons. This generalized sum rule, due to Ji and Osborne, reduces to the GDH sum rule at Q2 = 0 and to the Bjorken sum rule at Q2 >> 1 GeV2. By studying the Q2 evolution of the extended GDH sum, one learns about the transition from quark-like behavior to hadronic-like behavior. We measured inclusive polarized cross sections by scattering high energy polarized electrons off the new TJNAF polarized 3He target with both longitudinal and transverse target orientations. The high density 3He target, based on optical pumping and spin exchange, was used as an effective neutron target. The target maintained a polarization of about 35% at beam currents as high as 151tA. We describe the precision 3He polarimetry leading to a systematic uncertainty of the target polarization of 4% (relative). A strained GaAs photocathode was utilized in the polarized electron gun, which provided an electron beam with a polarization of about 70%, known to 3% (relative). By using six different beam energies (between 0.86 and 5.06 GeV) and a fixed scattering angle of 15.5°, a wide kinematic coverage was achieved, with 0.02 GeV2< Q2 <1 GcV2 and 0.5 GeV< W < 2.5 GeV for the squared momentum transfer and invariant mass, respectively. From the measured cross sections we extract the 3He spin structure functions He and g1e Finally, we determine the extended GDH sum for the range 0.1 GeV2< Q2 <1 GeV2 for 3He and the neutron.

  14. Depolarization and Spin Filtering Studies

    SciTech Connect

    Rathmann, Frank

    2008-04-30

    We present a short overview of the PAX physics case for polarized antiprotons. In order to progress towards a stored polarized antiproton beam, it is crucial to understand the interaction of polarized protons with unpolarized electrons. Therefore, the future investigations which address in particular the contributions of electrons to the polarization buildup of a stored proton beam, are presented here in more detail. The foreseen spin-filtering experiments at COSY-Juelich and at the AD of CERN are briefly discussed as well.

  15. A new ^3He-^129Xe Co-magnetometer using a Ramsey measurement sequence and Rb-K magnetometer for spin detection

    NASA Astrophysics Data System (ADS)

    Kabcenell, Aaron; Kominis, Iannis; Romalis, Michael

    2012-06-01

    Noble gas co-magnetometers have been used for many precision measurements, but their sensitivity is still very far from fundamental limits. We are exploring a new approach for operation of a ^3He-^129Xe co-magnetometer that uses a sensitive Rb-K magnetometer as a spin detector. By placing the noble gas atoms inside the magnetometer cell we can increase their magnetic signal using the Fermi-contact interaction, representing a gain of nearly 500 for ^129Xe, and achieve nearly quantum-noise limited detection of nuclear spins. In order to take advantage of the long coherence times of ^3He and^129Xe, the precession measurement is based on the Ramsey method of separated oscillatory fields and will be performed in an alkali-metal-free volume. The gas is then transported to the spin detector using techniques developed for remote NMR detection. The sensitivity of this approach is estimated to be on the order of 10-13 Hz/day^1/2, making it several orders of magnitude more sensitive than the best existing co-magnetometers. We are currently performing tests of the Ramsey measurement method and the sensitivity of the spin detector.

  16. Highly efficient spin filtering of ballistic electrons

    NASA Astrophysics Data System (ADS)

    Steinmuller, S. J.; Trypiniotis, T.; Cho, W. S.; Hirohata, A.; Lew, W. S.; Vaz, C. A.; Bland, J. A.

    2004-04-01

    Spin dependent electron transport in hybrid Au/Co/Cu/NiFe/n-GaAs spin valve Schottky barrier structures was investigated using photoexcitation at various wavelengths. For excitation with the photon energy well above the Schottky barrier height we found a ˜2400% increase in helicity dependent photocurrent on switching the spin valve from parallel to antiparallel alignment. Our observations provide clear evidence for highly efficient spin filtering of spin polarized ballistic electrons.

  17. Spin selective filtering of polariton condensate flow

    SciTech Connect

    Gao, T.; Antón, C.; Martín, M. D.; Liew, T. C. H.; Hatzopoulos, Z.; Viña, L.; Eldridge, P. S.; Savvidis, P. G.

    2015-07-06

    Spin-selective spatial filtering of propagating polariton condensates, using a controllable spin-dependent gating barrier, in a one-dimensional semiconductor microcavity ridge waveguide is reported. A nonresonant laser beam provides the source of propagating polaritons, while a second circularly polarized weak beam imprints a spin dependent potential barrier, which gates the polariton flow and generates polariton spin currents. A complete spin-based control over the blocked and transmitted polaritons is obtained by varying the gate polarization.

  18. Measurement of the 3He Spin Structure Functions in the Resonance Region: A Test of Quark-Hadron Duality on the Neutron

    SciTech Connect

    Solvignon, Patricia

    2006-08-31

    One of the biggest challenges in the study of the nucleon structure is the understanding of the transition from partonic degrees of freedom to hadronic degrees of freedom. In 1970, Bloom and Gilman noticed that structure function data taken at SLAC in the resonance region average to the scaling curve of deep inelastic scattering (DIS). Early theoretical interpretations suggested that these two very different regimes can be linked under the condition that the quark-gluon and quark-quark interactions are suppressed. Substantial efforts are ongoing to investigate this phenomenon both experimentally and theoretically. Quark-hadron duality has been confirmed for the unpolarized structure function F{sub 2} of the proton and the deuteron using data from the experimental Hall C at Jefferson Lab (JLab). Indications of duality have been seen for the proton polarized structure function g{sub 1} and the virtual photon asymmetry A{sub 1} at JLab Hall B and HERMES. Because of the different resonance behavior, it is expected that the onset of duality for the neutron will happen at lower momentum transfer than for the proton. Now that precise spin structure data in the DIS region are available at large x, data in the resonance region are greatly needed in order to test duality in spin-dependent structure functions. The goal of experiment E01-012 was to provide such data on the neutron ({sup 3}He) in the moderate momentum transfer (Q{sup 2}) region, 1.0 < Q{sup 2} < 4.0 (GeV/c{sup 2}), where duality is expected to hold. The experiment ran successfully in early 2003 at Jefferson Lab in Hall B. It was an inclusive measurement of longitudinally polarized electrons scattering from a longitudinally or transversely polarized {sup 3}He target. Asymmetries and cross section differences were measured in order to extract the {sup 3}He spin structure function g{sub 1} and virtual photon asymmetry A{sub 1} in the resonance region. A test of quark-hadron duality has then been performed for the

  19. Spin filter and spin valve in ferromagnetic graphene

    SciTech Connect

    Song, Yu Dai, Gang

    2015-06-01

    We propose and demonstrate that a EuO-induced and top-gated graphene ferromagnetic junction can be simultaneously operated as a spin filter and a spin valve. We attribute such a remarkable result to a coexistence of a half-metal band and a common energy gap for opposite spins in ferromagnetic graphene. We show that both the spin filter and the spin valve can be effectively controlled by a back gate voltage, and they survive for practical metal contacts and finite temperature. Specifically, larger single spin currents and on-state currents can be reached with contacts with work functions similar to graphene, and the spin filter can operate at higher temperature than the spin valve.

  20. Measurement of the Target-Normal Single-Spin Asymmetry in Deep-Inelastic Scattering from the Reaction 3He{uparrow}(e,e')X

    SciTech Connect

    Katich, Joseph; Qian, Xin; Zhao, Yuxiang; Allada, Kalyan; Aniol, Konrad; Annand, John; Averett, Todd; Benmokhtar, Fatiha; Bertozzi, William; Bradshaw, Elliott; Bosted, Peter; Camsonne, Alexandre; Canan, Mustafa; Cates, Gordon; Chen, Chunhua; Chen, Jian-Ping; Chen, Wei; Chirapatpimol, Khem; Chudakov, Eugene; Cisbani, Evaristo; Cornejo, Juan; Cusanno, Francesco; Dalton, Mark; Deconinck, Wouter; De Jager, Cornelis; De Leo, Raffaele; Deng, Xiaoyan; Deur, Alexandre; Ding, Huaibo; Dolph, Peter; Dutta, Chiranjib; Dutta, Dipangkar; El Fassi, Lamiaa; Frullani, Salvatore; Gao, Haiyan; Garibaldi, Franco; Gaskell, David; Gilad, Gilad; Gilman, Ronald; Glamazdin, Oleksandr; Golge, Serkan; Guo, Lei; Hamilton, David; Hansen, Jens-Ole; Higinbotham, Douglas; Holmstrom, Timothy; Huang, Jijun; Huang, Min; Ibrahim Abdalla, Hassan; Iodice, Mauro; Jin, Ge; Jones, Mark; Kelleher, Aidan; Kim, Wooyoung; Kolarkar, Ameya; Korsch, Wolfgang; LeRose, John; Li, Xiaomei; Li, Y; Lindgren, Richard; Liyanage, Nilanga; Long, Elena; Lu, Hai-jiang; Margaziotis, Demetrius; Markowitz, Pete; Marrone, Stefano; McNulty, Dustin; Meziani, Zein-Eddine; Michaels, Robert; Moffit, Bryan; Munoz Camacho, Carlos; Nanda, Sirish; Narayan, Amrendra; Nelyubin, Vladimir; Norum, Blaine; Oh, Yoomin; Osipenko, Mikhail; Parno, Diana; Peng, Jen-chieh; Phillips, Sarah; Posik, Matthew; Puckett, Andrew; Qiang, Yi; Rakhman, Abdurahim; Ransome, Ronald; Riordan, Seamus; Saha, Arunava; Sawatzky, Bradley; Schulte, Elaine; Shahinyan, Albert; Hashemi Shabestari, Mitra; Sirca, Simon; Stepanyan, Stepan; Subedi, Ramesh; Sulkosky, Vincent; Tang, Liguang; Tobias, William; Urciuoli, Guido; Vilardi, Ignazio; Wang, Kebin; Wang, Y; Wojtsekhowski, Bogdan; Yan, X; Yao, Huan; Ye, Yunxiu; Ye, Z; Yuan, Lulin; Zhan, Xiaohui; Zhang, Yi; Zhang, Y -W; Zhao, Bo; Zheng, Xiaochao; Zhu, Lingyan; Zhu, Xiaofeng; Zong, Xing

    2014-07-01

    We report the first measurement of the target single-spin asymmetry in deep-inelastic scattering from the inclusive reaction 3He{uparrow}(e,e')X on a 3He gas target polarized normal to the lepton plane. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.73He cross section ratios. The measured neutron asymmetries are negative with an average value of (−1.04+/-0.38)×10−2 for invariant mass W>2 GeV, which is non-zero at the 2.75sigma level. Theoretical calculations, which assume two-photon exchange with quasi-free quarks, predict a neutron asymmetry of O(10−4) when both photons couple to one quark, and O(10−2) for the photons coupling to different quarks. Our measured asymmetry agrees both in sign and magnitude with the prediction that uses input based on the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.

  1. Measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the reaction (3)He(↑)(e,e')X.

    PubMed

    Katich, J; Qian, X; Zhao, Y X; Allada, K; Aniol, K; Annand, J R M; Averett, T; Benmokhtar, F; Bertozzi, W; Bradshaw, P C; Bosted, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J-P; Chen, W; Chirapatpimol, K; Chudakov, E; Cisbani, E; Cornejo, J C; Cusanno, F; Dalton, M M; Deconinck, W; de Jager, C W; De Leo, R; Deng, X; Deur, A; Ding, H; Dolph, P A M; Dutta, C; Dutta, D; El Fassi, L; Frullani, S; Gao, H; Garibaldi, F; Gaskell, D; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Guo, L; Hamilton, D; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, J; Huang, M; Ibrahim, H F; Iodice, M; Jiang, X; Jin, G; Jones, M K; Kelleher, A; Kim, W; Kolarkar, A; Korsch, W; LeRose, J J; Li, X; Li, Y; Lindgren, R; Liyanage, N; Long, E; Lu, H-J; Margaziotis, D J; Markowitz, P; Marrone, S; McNulty, D; Meziani, Z-E; Michaels, R; Moffit, B; Muñoz Camacho, C; Nanda, S; Narayan, A; Nelyubin, V; Norum, B; Oh, Y; Osipenko, M; Parno, D; Peng, J C; Phillips, S K; Posik, M; Puckett, A J R; Qiang, Y; Rakhman, A; Ransome, R D; Riordan, S; Saha, A; Sawatzky, B; Schulte, E; Shahinyan, A; Shabestari, M H; Širca, S; Stepanyan, S; Subedi, R; Sulkosky, V; Tang, L-G; Tobias, A; Urciuoli, G M; Vilardi, I; Wang, K; Wang, Y; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yuan, L; Zhan, X; Zhang, Y; Zhang, Y-W; Zhao, B; Zheng, X; Zhu, L; Zhu, X; Zong, X

    2014-07-11

    We report the first measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the inclusive reaction 3)He(↑)(e,e')X on a polarized (3)He gas target. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.73)He cross-section ratios. The measured neutron asymmetries are negative with an average value of (-1.09±0.38)×10(-2) for invariant mass W>2  GeV, which is nonzero at the 2.89σ level. Our measured asymmetry agrees both in sign and magnitude with a two-photon-exchange model prediction that uses input from the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering. PMID:25062169

  2. Single Spin Asymmetries in Charged Pion Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized $^3$He Target

    SciTech Connect

    Qian, X; Allada, K; Huang, J; Katich, J; Wang, Y; Zhang, Y; Aniol, K; Annand, J.R.M.; Averett, T; Benmokhtar, F; Bertozzi, W; Bradshaw, P C; Bosted, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J -P; Chen, W; Chirapatpimol, K; Chudakov, E; Cisbani, E; Cornejo, J C; Cusanno, F; Dalton, M M; Deconinck, W; de Jager, C W; De Leo, R; Deng, X; Deur, A; Ding, H; Dolph, P.A.M.; Dutta, D; El Fassi, L; Frullani, S; Gao, H; Garibaldi, F; Gaskell, D; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Guo, L; Hamilton, D; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, M; Ibrahim, H F; Iodice, M; Jiang, X; Jin, G; Jones, M K; Kelleher, A; Kim, W; Kolarkar, A; Korsch, W; LeRose, J J; Li, X; Li, Y; Lindgren, R; Liyanage, N; Long, E; Lu, H -J; Margaziotis, D J; Markowitz, P; Marrone, S; McNulty, D; Meziani, Z -E; Michaels, R; Moffit, B; Munoz Camacho, C; Nanda, S; Narayan, A; Nelyubin, V; Norum, B; Oh, Y; Osipenko, M; Parno, D; Peng, J C; Phillips, S K; Posik, M; Puckett, A.J.R.; Qiang, Y; Rakhman, A; Ransome, R D; Riordan, S; Saha, A; Sawatzky, B; Schulte, E; Shahinyan, A; Shabestari, M H; Sirca, S; Stepanyan, S; Subedi, R; Sulkosky, V; Tang, L -G; Tobias, A; Urciuoli, G M; Vilardi, I; Wang, K; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yuan, L; Zhan, X; Zhang, Y -W; Zhao, B; Zheng, X; Zhu, L; Zhu, X; Zong, X

    2011-08-01

    We report the first measurement of target single spin asymmetries in the semi-inclusive $^3{He}(e,e'\\pi^\\pm)X$ reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.14 $< x <$ 0.34 with 1.3 $3$He are consistent with zero, except for the $\\pi^+$ moment at $x=0.34$, which deviates from zero by 2.3$\\sigma$. While the $\\pi^-$ Sivers moments are consistent with zero, the $\\pi^+$ Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and the measured cross section ratio of proton to $^3$He, and are largely consistent with the predictions of phenomenological fits and quark model calculations.

  3. Topological Septet Pairing with Spin-3/2 Fermions: High-Partial-Wave Channel Counterpart of the 3He -B Phase

    NASA Astrophysics Data System (ADS)

    Yang, Wang; Li, Yi; Wu, Congjun

    2016-08-01

    We systematically generalize the exotic 3He -B phase, which not only exhibits unconventional symmetry but is also isotropic and topologically nontrivial, to arbitrary partial-wave channels with multicomponent fermions. The concrete example with four-component fermions is illustrated including the isotropic f -, p -, and d -wave pairings in the spin septet, triplet, and quintet channels, respectively. The odd partial-wave channel pairings are topologically nontrivial, while pairings in even partial-wave channels are topologically trivial. The topological index reaches the largest value of N2 in the p -wave channel (N is half of the fermion component number). The surface spectra exhibit multiple linear and even high order Dirac cones. Applications to multiorbital condensed matter systems and multicomponent ultracold large spin fermion systems are discussed.

  4. Topological Septet Pairing with Spin-3/2 Fermions: High-Partial-Wave Channel Counterpart of the ^{3}He-B Phase.

    PubMed

    Yang, Wang; Li, Yi; Wu, Congjun

    2016-08-12

    We systematically generalize the exotic ^{3}He-B phase, which not only exhibits unconventional symmetry but is also isotropic and topologically nontrivial, to arbitrary partial-wave channels with multicomponent fermions. The concrete example with four-component fermions is illustrated including the isotropic f-, p-, and d-wave pairings in the spin septet, triplet, and quintet channels, respectively. The odd partial-wave channel pairings are topologically nontrivial, while pairings in even partial-wave channels are topologically trivial. The topological index reaches the largest value of N^{2} in the p-wave channel (N is half of the fermion component number). The surface spectra exhibit multiple linear and even high order Dirac cones. Applications to multiorbital condensed matter systems and multicomponent ultracold large spin fermion systems are discussed. PMID:27563972

  5. Fluorine Functionalized BNNT as a Spin Filter

    NASA Astrophysics Data System (ADS)

    Dhungana, Kamal; Pati, Ranjit

    2015-03-01

    Spin filtering is a phenomenon that allows one to generate spin-polarized carriers in a circuit comprised of a magnetic channel sandwiched between two non-magnetic electrodes. In recent years, the quest for a novel low-dimensional metal-free magnetic channel that would exhibit both magnetism at a higher temperature and excellent spin filtering property has been intensively pursued. Herein, using a first-principles approach, we study the magnetic property of fluorine functionalized boron nitride nanotube (F-BNNT). A long range ferromagnetic spin ordering is found to occur in the F-BNNT at temperature much above the room temperature. Our spin polarized transport study shows that the fluorine functionalization in BNNT not only enhances its conductance by more than two orders, which is in excellent agreement with the experimental report, but also makes it a perfect spin filter. This work is supported by the NSF through Grant No. 1249504.

  6. Spin-exchange optically pumped polarized 3He target for low-energy charged particle scattering experiments

    NASA Astrophysics Data System (ADS)

    Katabuchi, T.; Buscemi, S.; Cesaratto, J. M.; Clegg, T. B.; Daniels, T. V.; Fassler, M.; Neufeld, R. B.; Kadlecek, S.

    2005-03-01

    We have constructed, tested, and calibrated a polarized He3 target system which facilitates p-He3 elastic scattering at proton energies as low as 2MeV. This system consists of a target cell placed in a uniform B field inside a scattering chamber and an external optical pumping station utilizing Rb spin exchange. Computer-controlled valves allow polarized He3 gas to be transferred quickly between the optical pumping station and the spherical Pyrex target cell, which has Kapton film covering apertures for the passing beam and the scattering particles. The magnetic field required to maintain He3 polarization in the target cell is created with a compact, shielded sine-theta coil. Target gas polarimetry is accomplished using nuclear magnetic resonance and calibrated using the known analyzing power of α-He3 scattering.

  7. Single spin asymmetries in charged kaon production from semi-inclusive deep inelastic scattering on a transversely polarized 3He target

    NASA Astrophysics Data System (ADS)

    Zhao, Y. X.; Wang, Y.; Allada, K.; Aniol, K.; Annand, J. R. M.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Bradshaw, P. C.; Bosted, P.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J.-P.; Chen, W.; Chirapatpimol, K.; Chudakov, E.; Cisbani, E.; Cornejo, J. C.; Cusanno, F.; Dalton, M. M.; Deconinck, W.; de Jager, C. W.; De Leo, R.; Deng, X.; Deur, A.; Ding, H.; Dolph, P. A. M.; Dutta, C.; Dutta, D.; El Fassi, L.; Frullani, S.; Gao, H.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Guo, L.; Hamilton, D.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, J.; Huang, M.; Ibrahim, H. F.; Iodice, M.; Jiang, X.; Jin, G.; Jones, M. K.; Katich, J.; Kelleher, A.; Kim, W.; Kolarkar, A.; Korsch, W.; LeRose, J. J.; Li, X.; Li, Y.; Lindgren, R.; Liyanage, N.; Long, E.; Lu, H.-J.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; McNulty, D.; Meziani, Z.-E.; Michaels, R.; Moffit, B.; Muñoz Camacho, C.; Nanda, S.; Narayan, A.; Nelyubin, V.; Norum, B.; Oh, Y.; Osipenko, M.; Parno, D.; Peng, J.-C.; Phillips, S. K.; Posik, M.; Puckett, A. J. R.; Qian, X.; Qiang, Y.; Rakhman, A.; Ransome, R.; Riordan, S.; Saha, A.; Sawatzky, B.; Schulte, E.; Shahinyan, A.; Shabestari, M. H.; Širca, S.; Stepanyan, S.; Subedi, R.; Sulkosky, V.; Tang, L.-G.; Tobias, A.; Urciuoli, G. M.; Vilardi, I.; Wang, K.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Ye, Y.; Ye, Z.; Yuan, L.; Zhan, X.; Zhang, Y.; Zhang, Y.-W.; Zhao, B.; Zheng, X.; Zhu, L.; Zhu, X.; Zong, X.; Jefferson Lab Hall A Collaboration

    2014-11-01

    We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized 3He target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of 0.1

  8. Relaxation time of 3He

    NASA Astrophysics Data System (ADS)

    Gao, Hayian

    2004-10-01

    The next generation of searches for the neutron electric dipole moment using ultra cold neutrons will use polarized ^3He as a co-magnetometer. The first such experiment has been proposed, with a goal of improving the current limit on the neutron EDM by two orders of magnitude. This experiment requires a systematic study of the properties of polarized ^3He at cryogenic temperatures under actual experimental conditions. These experimental conditions include polarized ^3He mixed in a bath of superfluid ^4He in low magnetic field and held in an acrylic cell which is coated with deuterated TetraphenylButadiene . Parts of these systematic studies will be done at Duke University using a newly built, novel refillable double cell ^3 He polarizer based on spin exchange optical pumping with Rubidium vapor. The polarimetry for this apparatus is done with a NMR polarimeter using the adiabatic fast passage method. An alternate polarimeter using free induction decay method is also being built. This apparatus is being used to study the relaxation time and other critical properties of polarized ^3He at temperatures ranging from 2.3 - 4.2 K, under simulated experimental conditions. We will present details about this novel polarizer and show preliminary results of our measurements.

  9. Beam-target double-spin asymmetry A{LT} in charged pion production from deep inelastic scattering on a transversely polarized {3}He target at 1.4

    PubMed

    Huang, J; Allada, K; Dutta, C; Katich, J; Qian, X; Wang, Y; Zhang, Y; Aniol, K; Annand, J R M; Averett, T; Benmokhtar, F; Bertozzi, W; Bradshaw, P C; Bosted, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J-P; Chen, W; Chirapatpimol, K; Chudakov, E; Cisbani, E; Cornejo, J C; Cusanno, F; Dalton, M M; Deconinck, W; de Jager, C W; De Leo, R; Deng, X; Deur, A; Ding, H; Dolph, P A M; Dutta, D; El Fassi, L; Frullani, S; Gao, H; Garibaldi, F; Gaskell, D; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Guo, L; Hamilton, D; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, M; Ibrahim, H F; Iodice, M; Jiang, X; Jin, G; Jones, M K; Kelleher, A; Kim, W; Kolarkar, A; Korsch, W; Lerose, J J; Li, X; Li, Y; Lindgren, R; Liyanage, N; Long, E; Lu, H-J; Margaziotis, D J; Markowitz, P; Marrone, S; McNulty, D; Meziani, Z-E; Michaels, R; Moffit, B; Muñoz Camacho, C; Nanda, S; Narayan, A; Nelyubin, V; Norum, B; Oh, Y; Osipenko, M; Parno, D; Peng, J C; Phillips, S K; Posik, M; Puckett, A J R; Qiang, Y; Rakhman, A; Ransome, R D; Riordan, S; Saha, A; Sawatzky, B; Schulte, E; Shahinyan, A; Shabestari, M H; Sirca, S; Stepanyan, S; Subedi, R; Sulkosky, V; Tang, L-G; Tobias, A; Urciuoli, G M; Vilardi, I; Wang, K; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yuan, L; Zhan, X; Zhang, Y-W; Zhao, B; Zheng, X; Zhu, L; Zhu, X; Zong, X

    2012-02-01

    We report the first measurement of the double-spin asymmetry A{LT} for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized {3}He target. The kinematics focused on the valence quark region, 0.163}He asymmetries and proton over {3}He cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function g{1T}{q} and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for π{-} production on {3}He and the neutron, while our π{+} asymmetries are consistent with zero. PMID:22400926

  10. Spin voltage generation across rare earth spin filter barriers

    NASA Astrophysics Data System (ADS)

    Miao, Guoxing; Chang, Joonyeon; Moodera, Jagadeesh

    2011-03-01

    When a metal is in close contact with a rare-earth based magnetic compound, strong exchange interaction exists between the localized 4f electrons and the free moving conduction electrons. One important consequence is that the spin degeneracy among the conduction electrons is lifted, showing up as an effective Zeeman splitting higher than tens of Tesla in low dimensional systems such as graphene and other 2DEG. We perform our work using a vertical transport geometry, which consists of double spin filtering barriers based on a ferromagnetic Eu chalcogenide - EuS. A thin Al metallic layer is sandwiched in the middle and its conduction electrons thus experience the strong spin splitting, which is subsequently detected via the spin filtering effect. A spontaneous spin dependent voltage appears across such a device, and its polarity is directly determined by the EuS/Al interface. The voltage level difference between the spin-parallel and -antiparallel configurations is as large as a few mV. Such spin splitting also induces a clear universal behavior in the observed TMR bias dependence. Such spin voltage effect offers a possibility of directly converting magnetic exchange energy into electrical power. This work is supported by NSF DMR 0504158, ONR N00014-06-1-0235, and KIST-MIT project funds.

  11. Filter design for hybrid spin gates

    NASA Astrophysics Data System (ADS)

    Albrecht, Andreas; Plenio, Martin B.

    2015-08-01

    The impact of control sequences on the environmental coupling of a quantum system can be described in terms of a filter. Here we analyze how the coherent evolution of two interacting spins subject to periodic control pulses, using the example of a nitrogen vacancy center coupled to a nuclear spin, can be described in the filter framework in both the weak- and the strong-coupling limit. A universal functional dependence around the filter resonances then allows for tuning the coupling type and strength. We show how the validity range of the filter description, originally limited to small rotation angles, can be extended to the long time limit by time-sliced evolution sequences. Based on that insight, the construction of tunable, noise decoupled, conditional gates composed of alternating pulse sequences is proposed. In particular such an approach can lead to a significant improvement in fidelity as compared to a strictly periodic control sequence. Moreover we analyze the decoherence impact, the relation to the filter for classical noise known from dynamical decoupling sequences, and we outline how an alternating sequence can improve spin sensing protocols.

  12. Spin Filtering Studies at COSY and AD

    SciTech Connect

    Nass, Alexander

    2009-08-04

    The high physics potential of experiments with stored high-energy polarized antiprotons led to the proposal of PAX (Polarized Antiproton eXperiment) for the High Energy Storage Ring (HESR) of the FAIR at GSI (Darmstadt/Germany). It is proposed to polarize a stored antiproton beam by means of spin filtering with a polarized H (D) gas target. The feasibility of spin filtering has been demonstrated in the FILTEX experiment. The current interpretation foresees a self-cancellation of the electron contribution to the filtering process and only the hadronic contribution is effective. Several experimental studies with protons (at COSY/Juelich) as well as antiprotons (at AD/CERN) will be carried out to test the principle and measure p-barp-vector and p-bard-vector cross sections. A polarized internal gas target (PIT) with surrounding Silicon detectors immersed into a low-beta section has to be set up.

  13. Spin filter for arbitrary spins by substrate engineering.

    PubMed

    Pal, Biplab; Römer, Rudolf A; Chakrabarti, Arunava

    2016-08-24

    We design spin filters for particles with potentially arbitrary spin [Formula: see text] using a one-dimensional periodic chain of magnetic atoms as a quantum device. Describing the system within a tight-binding formalism we present an analytical method to unravel the analogy between a one-dimensional magnetic chain and a multi-strand ladder network. This analogy is crucial, and is subsequently exploited to engineer gaps in the energy spectrum by an appropriate choice of the magnetic substrate. We obtain an exact correlation between the magnitude of the spin of the incoming beam of particles and the magnetic moment of the substrate atoms in the chain desired for opening up of a spectral gap. Results of spin polarized transport, calculated within a transfer matrix formalism, are presented for particles having half-integer as well as higher spin states. We find that the chain can be made to act as a quantum device which opens a transmission window only for selected spin components over certain ranges of the Fermi energy, blocking them in the remaining part of the spectrum. The results appear to be robust even when the choice of the substrate atoms deviates substantially from the ideal situation, as verified by extending the ideas to the case of a 'spin spiral'. Interestingly, the spin spiral geometry, apart from exhibiting the filtering effect, is also seen to act as a device flipping spins-an effect that can be monitored by an interplay of the system size and the period of the spiral. Our scheme is applicable to ultracold quantum gases, and might inspire future experiments in this direction. PMID:27352129

  14. A high-spin organic diradical as a spin filter.

    PubMed

    Shil, Suranjan; Bhattacharya, Debojit; Misra, Anirban; Klein, Douglas J

    2015-09-28

    Here, in this work we have designed a molecular bridge structure which can be used as a spin filter where the prototypical highly ferromagnetic m-phenylene connected bis(aminoxyl) diradical is used as a bridging fragment between two semi-infinitely widened gold (Au) electrodes along the [100] direction. A state-of-the-art non-equilibrium Green function's (NEGF) method coupled with the density functional theory (DFT) was carried out on this two-probe molecular bridge system to understand its electrical spin transport characteristics. The spin current at various bias voltages from 0.00 V to 4.00 V at intervals of 0.20 V for this Au-diradical-Au molecular junction is evaluated. We also quantify the bias-dependent spin injection coefficients (BDSIC) at different bias voltages and also the spin-filter efficiency at equilibrium, i.e., at zero bias voltage. Also plots of BDSIC vs. voltage, the up- and down-spin current vs. voltage (I-V) curves, and density of states (DOS) at zero bias voltage are evaluated. PMID:26287641

  15. Spin filter for arbitrary spins by substrate engineering

    NASA Astrophysics Data System (ADS)

    Pal, Biplab; Römer, Rudolf A.; Chakrabarti, Arunava

    2016-08-01

    We design spin filters for particles with potentially arbitrary spin S≤ft(=1/2,1,3/2,\\ldots \\right) using a one-dimensional periodic chain of magnetic atoms as a quantum device. Describing the system within a tight-binding formalism we present an analytical method to unravel the analogy between a one-dimensional magnetic chain and a multi-strand ladder network. This analogy is crucial, and is subsequently exploited to engineer gaps in the energy spectrum by an appropriate choice of the magnetic substrate. We obtain an exact correlation between the magnitude of the spin of the incoming beam of particles and the magnetic moment of the substrate atoms in the chain desired for opening up of a spectral gap. Results of spin polarized transport, calculated within a transfer matrix formalism, are presented for particles having half-integer as well as higher spin states. We find that the chain can be made to act as a quantum device which opens a transmission window only for selected spin components over certain ranges of the Fermi energy, blocking them in the remaining part of the spectrum. The results appear to be robust even when the choice of the substrate atoms deviates substantially from the ideal situation, as verified by extending the ideas to the case of a ‘spin spiral’. Interestingly, the spin spiral geometry, apart from exhibiting the filtering effect, is also seen to act as a device flipping spins—an effect that can be monitored by an interplay of the system size and the period of the spiral. Our scheme is applicable to ultracold quantum gases, and might inspire future experiments in this direction.

  16. Vortices in rotating superfluid 3He.

    PubMed

    Lounasmaa, O V; Thuneberg, E

    1999-07-01

    In this review we first present an introduction to 3He and to the ROTA collaboration under which most of the knowledge on vortices in superfluid 3He has been obtained. In the physics part, we start from the exceptional properties of helium at millikelvin temperatures. The dilemma of rotating superfluids is presented. In 4He and in 3He-B the problem is solved by nucleating an array of singular vortex lines. Their experimental detection in 3He by NMR is described next. The vortex cores in 3He-B have two different structures, both of which have spontaneously broken symmetry. A spin-mass vortex has been identified as well. This object is characterized by a flow of spins around the vortex line, in addition to the usual mass current. A great variety of vortices exist in the A phase of 3He; they are either singular or continuous, and their structure can be a line or a sheet or fill the whole liquid. Altogether seven different types of vortices have been detected in 3He by NMR. We also describe briefly other experimental methods that have been used by ROTA scientists in studying vortices in 3He and some important results thus obtained. Finally, we discuss the possible applications of experiments and theory of 3He to particle physics and cosmology. In particular, we report on experiments where superfluid 3He-B was heated locally by absorption of single neutrons. The resulting events can be used to test theoretical models of the Big Bang at the beginning of our universe. PMID:10393895

  17. Vortices in rotating superfluid 3He

    PubMed Central

    Lounasmaa, Olli V.; Thuneberg, Erkki

    1999-01-01

    In this review we first present an introduction to 3He and to the ROTA collaboration under which most of the knowledge on vortices in superfluid 3He has been obtained. In the physics part, we start from the exceptional properties of helium at millikelvin temperatures. The dilemma of rotating superfluids is presented. In 4He and in 3He-B the problem is solved by nucleating an array of singular vortex lines. Their experimental detection in 3He by NMR is described next. The vortex cores in 3He-B have two different structures, both of which have spontaneously broken symmetry. A spin-mass vortex has been identified as well. This object is characterized by a flow of spins around the vortex line, in addition to the usual mass current. A great variety of vortices exist in the A phase of 3He; they are either singular or continuous, and their structure can be a line or a sheet or fill the whole liquid. Altogether seven different types of vortices have been detected in 3He by NMR. We also describe briefly other experimental methods that have been used by ROTA scientists in studying vortices in 3He and some important results thus obtained. Finally, we discuss the possible applications of experiments and theory of 3He to particle physics and cosmology. In particular, we report on experiments where superfluid 3He-B was heated locally by absorption of single neutrons. The resulting events can be used to test theoretical models of the Big Bang at the beginning of our universe. PMID:10393895

  18. Development of polarized 3He ion source

    NASA Astrophysics Data System (ADS)

    Tanaka, M.; Takahashi, Y.; Shimoda, T.; Yasui, S.; Yosoi, M.; Takahisa, K.; Shimakura, N.

    2007-02-01

    A long history on the polarized 3He ion source developed at RCNP is presented. We started with an "OPPIS" (Optical Pumping Polarized Ion Source) and later found the fundamental difficulties in the OPPIS. To overcome them an "EPPIS" (Electron Pumping Polarized Ion Source) was proposed and its validity was experimentally proven. However, a serious technical disadvantage was also found in the EPPIS. To avoid this disadvantage we proposed a new concept, "SEPIS" (Spin Exchange Polarized Ion Source), which uses an enhanced spin-exchange cross section theoretically expected at low 3He+ incident energies for the 3He+ + Rb system. Next, we describe the present status of the SEPIS development; construction of a bench test device allowing the measurements of not only the spin-exchange cross sections σse but also the electron capture cross sections σec for the 3He+ + Rb system. The latest experimental data on σec are presented and compared with other previous experimental data and the theoretical calculations. A design study of the SEPIS for practical use in nuclear (cyclotron) and particle physics (synchrotron) is shortly mentioned. Finally, we mention possibility to polarize ions heavier than 3He as an application of SEPIS. The theoretical calculation showed that σse comparable to that for the 3He+ + Rb is expected for the Li2+ + Rb system, which suggests that the SEPIS will hopefully be a general tool to polarize any heavy ions.

  19. Novel multipole Wien filter as three-dimensional spin manipulator

    SciTech Connect

    Yasue, T. Suzuki, M.; Koshikawa, T.; Tsuno, K.; Goto, S.; Arai, Y.

    2014-04-15

    Spin polarized electron beam is often used in material characterizations which relates to magnetism as well as in the high energy particle physics. The manipulation of the spin polarization toward the arbitrary direction is indispensable in such studies. In the present work, a novel multipole Wien filter is proposed as the three-dimensional spin manipulator, and a prototype 8-pole Wien filter is developed. It is applied to spin polarized low energy electron microscopy, and the variation of the magnetic contrast with managing the spin polarization is evaluated. It is confirmed that the novel multipole Wien filter can manipulate the spin polarization three-dimensionally.

  20. Kalman Filter for Spinning Spacecraft Attitude Estimation

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis; Sedlak, Joseph E.

    2008-01-01

    This paper presents a Kalman filter using a seven-component attitude state vector comprising the angular momentum components in an inertial reference frame, the angular momentum components in the body frame, and a rotation angle. The relatively slow variation of these parameters makes this parameterization advantageous for spinning spacecraft attitude estimation. The filter accounts for the constraint that the magnitude of the angular momentum vector is the same in the inertial and body frames by employing a reduced six-component error state. Four variants of the filter, defined by different choices for the reduced error state, are tested against a quaternion-based filter using simulated data for the THEMIS mission. Three of these variants choose three of the components of the error state to be the infinitesimal attitude error angles, facilitating the computation of measurement sensitivity matrices and causing the usual 3x3 attitude covariance matrix to be a submatrix of the 6x6 covariance of the error state. These variants differ in their choice for the other three components of the error state. The variant employing the infinitesimal attitude error angles and the angular momentum components in an inertial reference frame as the error state shows the best combination of robustness and efficiency in the simulations. Attitude estimation results using THEMIS flight data are also presented.

  1. PREFACE: JCNS Workshop on Modern Trends in Production and Applications of Polarized 3He

    NASA Astrophysics Data System (ADS)

    Ioffe, Alexander; Babcock, Earl; Gutberlet, Thomas

    2011-03-01

    Polarized neutron scattering techniques are an indispensable and highly requested tool for studying magnetic phenomena in condensed matter. The different coherent and incoherent scattering of isotopes such as protons and deuterons also allows applications of polarized neutrons in soft matter and biological studies of molecular and macromolecular dynamics. One method to polarize neutrons is to use polarized 3He gas which absorbs, or filters, one spin state of the neutron beam as it passes through it. Only about ten years ago, early polarized neutron scattering experiments using such 3He neutron spin filters (3He NSF) were being conducted using starting 3He polarizations of 55%. Currently there are two different commonly used methods to polarize high quantities of 3He. These methods both collisionally transfer spin polarization to ground state 3He nucleuses; one method uses optical pumping of an excited metastable state of 3He atoms, and the other uses optical pumping of the ground state of an alkali-metal vapour. Within the last decade immense progress in both methods has resulted in 3He polarizations of up to 80% being reported in atmosphere-pressure 3He cells by the world's leading labs. This progress in optical pumped 3He promises to give rise to much more efficient and novel polarized neutron scattering experiments as and also impacts other areas of science. Polarized 3He is additionally applied in research fields such as particle physics, fundamental studies and medicine. Thus not only the techniques and methods of polarization, but the research groups themselves exploring polarized 3He, have a large breadth and diversity spanning different fields of science and locations in the world. Given this diversity, it is rare for this community to meet as a group at any one meeting or conference. Because it is crucial to discuss new developments in 3He polarization in a multi-disciplinary international setting, an international workshop on "Modern Trends in Production

  2. First measurements of spin-dependent double-differential cross sections and the Gerasimov-Drell-Hearn Integrand from 3He(γ,n)pp at incident photon energies of 12.8 and 14.7 MeV.

    PubMed

    Laskaris, G; Ye, Q; Lalremruata, B; Ye, Q J; Ahmed, M W; Averett, T; Deltuva, A; Dutta, D; Fonseca, A C; Gao, H; Golak, J; Huang, M; Karwowski, H J; Mueller, J M; Myers, L S; Peng, C; Perdue, B A; Qian, X; Sauer, P U; Skibiński, R; Stave, S; Tompkins, J R; Weller, H R; Witała, H; Wu, Y K; Zhang, Y; Zheng, W

    2013-05-17

    The first measurement of the three-body photodisintegration of longitudinally polarized (3)He with a circularly polarized γ-ray beam was carried out at the High Intensity γ-ray Source facility located at Triangle Universities Nuclear Laboratory. The spin-dependent double-differential cross sections and the contributions from the three-body photodisintegration to the (3)He Gerasimov-Drell-Hearn integrand are presented and compared with state-of-the-art three-body calculations at the incident photon energies of 12.8 and 14.7 MeV. The data reveal the importance of including the Coulomb interaction between protons in three-body calculations. PMID:25167400

  3. Neutron polarizers based on polarized ^3He

    NASA Astrophysics Data System (ADS)

    Gentile, T. R.; Jones, G. L.; Thompson, A. K.; Fei, X.; Keith, C. D.; Rich, D.; Snow, W. M.; Penttila, S.

    1997-10-01

    Research is underway at NIST, Indiana Univ., and LANL to develop neutron polarizers and analyzers based on polarized ^3He. Such devices, which rely on the strong spin dependence of the neutron capture cross section by polarized ^3He, have applications in weak interaction physics and materials science. In addition, the technology for polarized ^3He production is directly applicable to polarized gas MRI of lungs, and polarized targets. Our program, which includes both the spin-exchange and metastability-exchange optical pumping methods, will be reviewed. Spin-exchange has been used to analyze a polarized cold neutron beam at NIST, and also for lung imaging in collaboration with the Univ. of Pennsylvania. In the metastable method, the ^3He is polarized at low pressure, and must be substantially compressed. A piston compressor has been designed for this goal at Indiana Univ. and is under construction. At NIST we have compressed polarized gas using an apparatus that is based on a modified commercial diaphragm pump.

  4. Single spin asymmetries in charged pion production from semi-inclusive deep inelastic scattering on a transversely polarized 3He Target at Q2 = 1.4-2.7 GeV2.

    PubMed

    Qian, X; Allada, K; Dutta, C; Huang, J; Katich, J; Wang, Y; Zhang, Y; Aniol, K; Annand, J R M; Averett, T; Benmokhtar, F; Bertozzi, W; Bradshaw, P C; Bosted, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J-P; Chen, W; Chirapatpimol, K; Chudakov, E; Cisbani, E; Cornejo, J C; Cusanno, F; Dalton, M M; Deconinck, W; de Jager, C W; De Leo, R; Deng, X; Deur, A; Ding, H; Dolph, P A M; Dutta, D; El Fassi, L; Frullani, S; Gao, H; Garibaldi, F; Gaskell, D; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Guo, L; Hamilton, D; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, M; Ibrahim, H F; Iodice, M; Jiang, X; Jin, G; Jones, M K; Kelleher, A; Kim, W; Kolarkar, A; Korsch, W; LeRose, J J; Li, X; Li, Y; Lindgren, R; Liyanage, N; Long, E; Lu, H-J; Margaziotis, D J; Markowitz, P; Marrone, S; McNulty, D; Meziani, Z-E; Michaels, R; Moffit, B; Camacho, C Muñoz; Nanda, S; Narayan, A; Nelyubin, V; Norum, B; Oh, Y; Osipenko, M; Parno, D; Peng, J C; Phillips, S K; Posik, M; Puckett, A J R; Qiang, Y; Rakhman, A; Ransome, R D; Riordan, S; Saha, A; Sawatzky, B; Schulte, E; Shahinyan, A; Shabestari, M H; Sirca, S; Stepanyan, S; Subedi, R; Sulkosky, V; Tang, L-G; Tobias, A; Urciuoli, G M; Vilardi, I; Wang, K; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yuan, L; Zhan, X; Zhang, Y-W; Zhao, B; Zheng, X; Zhu, L; Zhu, X; Zong, X

    2011-08-12

    We report the first measurement of target single spin asymmetries in the semi-inclusive (3)He(e,e'π(±))X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.16 < x < 0.35 with 1.4 < Q(2) < 2.7 GeV(2). The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The π(±) Collins moments for (3)He are consistent with zero, except for the π(+) moment at x = 0.35, which deviates from zero by 2.3σ. While the π(-) Sivers moments are consistent with zero, the π(+) Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to (3)He, and are largely consistent with the predictions of phenomenological fits and quark model calculations. PMID:21902386

  5. Towards Room Temperature Spin Filtering in Oxide Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Iwata-Harms, Jodi; Wong, Franklin; Arenholz, Elke; Suzuki, Yuri

    2012-02-01

    Spin filtering, in which the magnetic tunnel barrier preferentially filters spin-up and spin-down electrons from a nonmagnetic electrode, has been demonstrated in junction heterostructures. By incorporating two spin filtering barriers, double spin filter magnetic tunnel junctions (DSF-MTJs) were predicted to yield magnetoresistance (MR) values orders of magnitude larger than that of conventional magnetic tunnel junctions. Recently, DSF-MTJs have exhibited spin filtering with magnetic electrodes at room temperature and at low temperature with nonmagnetic electrodes in EuS-based devices [1,2]. We have fabricated DSF-MTJs with nonmagnetic SrRuO3 electrodes and room temperature ferrimagnets, NiFe2O4 and CoFe2O4, for spin filters in pursuit of room temperature functionality. Atomic force microscopy shows smooth films quantified by roughness values between 0.1--0.5nm. X-ray magnetic circular dichroism reveals ferromagnetic Ni^2+ and Co^2+, and element-specific hysteresis loops indicate the independent switching of the two spin filters. Transport data reveals junction MR and non-linear I-V characteristics consistent with tunneling. [4pt] [1] M.G. Chapline et al., PRB, 74, 014418 (2006).[0pt] [2] G.- X. Miao et al., PRL, 102, 076601 (2009).

  6. Dislocation motion in solid hcp 3He

    NASA Astrophysics Data System (ADS)

    Beamish, John; Cheng, Zhi Gang

    At temperatures above about 100 mK, dislocations reduce the shear modulus of hcp 4He by as much as 90 %. This occurs when dislocations thermally unbind from the 3He impurities that pin them, becoming extraordinarily mobile. The elastic softening is accompanied by a thermally activated dissipation peak due to the 3He impurities. At higher temperatures the dissipation has an ωT4 dependence caused by scattering of thermal phonons from moving dislocations. Previous measurements on the fermi solid, hcp 3He, showed a similar dislocation softening, but the corresponding dissipation was not measured. We have extended these measurements by measuring the temperature, amplitude and frequency dependence of both the shear modulus and the dissipation in hcp 3He. The dissipation behavior is very different from that of hcp 4He. Neither the impurity unbinding peak associated with the elastic softening, nor the high temperature phonon scattering dissipation, were observed. Instead, there is a large and non-thermally activated dissipation which is largest at low frequencies. We believe that this unexpected dissipation is associated with a new dislocation damping mechanism in 3He, perhaps associated with spin rearrangements caused by moving dislocations. This work was supported by a grant from NSERC Canada.

  7. Isospin-spin excitations in the A=58 mass region: The {sup 58}Ni({sup 3}He,t){sup 58}Cu reaction

    SciTech Connect

    Bes, D. R.; Civitarese, O.

    2008-07-15

    The experimental information on isospin-spin excitations around {sup 58}Ni is analyzed by using isoscalar and isovector pairing vibrations, Gamow-Teller (GT) modes, and their couplings. It is found that the proposed coupling scheme accounts for a sizable amount of the strength associated with isospin-spin excitations, which include transitions to both one- and two-phonon states. The calculations are performed within the framework of perturbation theory, accounting for the renormalization of the charge by the collective GT excitations.

  8. The n3He Experiment: Current Status

    NASA Astrophysics Data System (ADS)

    McCrea, Mark; n3He Collaboration

    2014-09-01

    The n3He experiment aims to make a high precision measurement of the hadronic weak interaction in the reaction n-> +3 He --> p + T by measuring the parity violating asymmetry in the direction of proton emission relative to the neutron polarization direction. As the weak interaction is the only interaction to violate parity this allows us to extract the much smaller weak interaction effects from the larger strong interaction effects. The range of the asymmetry is estimated to be (- 9 . 5 --> 2 . 5) ×10-8 . The goal is to measure this asymmetry with an accuracy of 2 ×10-8 to provide a benchmark for modern effective field theory calculations. n3He will run at the SNS Fundamental Neutron Physics Beamline. The combined target and detector is a multiwire 3He ionization chamber. A super mirror polarizer will be used to polarize the incoming cold neutron beam, and a spin flipper will reverse the spin in a sequence to control for systematic effects.

  9. Enhancing Spin Filters by Use of Bulk Inversion Asymmetry

    NASA Technical Reports Server (NTRS)

    Ting, David; Cartoixa,Xavier

    2007-01-01

    Theoretical calculations have shown that the degrees of spin polarization in proposed nonmagnetic semiconductor resonant tunneling spin filters could be increased through exploitation of bulk inversion asymmetry (BIA). These enhancements would be effected through suitable orientation of spin collectors (or spin-polarization- inducing lateral electric fields), as described below. Spin filters -- more precisely, sources of spin-polarized electron currents -- have been sought for research on, and development of, the emerging technological discipline of spintronics (spin-transport electronics). The proposed spin filters were to be based on the Rashba effect, which is an energy splitting of what would otherwise be degenerate quantum states, caused by a spinorbit interaction in conjunction with a structural-inversion asymmetry (SIA) in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. In a spin filter, the spin-polarized currents produced by the Rashba effect would be extracted by quantum-mechanical resonant tunneling.

  10. The 3He Supply Problem

    SciTech Connect

    Kouzes, Richard T.

    2009-05-01

    One of the main uses for 3He is in gas proportional counters for neutron detection. Radiation portal monitors deployed for homeland security and non-proliferation use such detectors. Other uses of 3He are for research detectors, commercial instruments, well logging detectors, dilution refrigerators, for targets or cooling in nuclear research, and for basic research in condensed matter physics. The US supply of 3He comes almost entirely from the decay of tritium used in nuclear weapons by the US and Russia. A few other countries contribute a small amount to the world’s 3He supply. Due to the large increase in use of 3He for homeland security, the supply has dwindled, and can no longer meet the demand. This white paper reviews the problems of supply, utilization, and alternatives.

  11. Recent Advances of Polarized 3He Target at Jefferson Lab

    SciTech Connect

    Yi Qiang

    2011-10-01

    Polarized {sup 3}He target has been widely used in nuclear and particle experiments to study the neutron structure in the spin degree of freedom, as most of the {sup 3}He spin is carried by the unpaired neutron. Spin-Exchange Optical Pumping (SEOP) process is used in Jefferson Lab Hall A to polarize its {sup 3}He target. Through developments in recent years, both the performance and corresponding polarimetry of such a target were greatly improved. Several experiments recently carried out in Hall A benefited remarkably from this target for the record highest figure of merit.

  12. Electron-Spin Filters Would Offer Spin Polarization Greater than 1

    NASA Technical Reports Server (NTRS)

    Ting, David Z.

    2009-01-01

    A proposal has been made to develop devices that would generate spin-polarized electron currents characterized by polarization ratios having magnitudes in excess of 1. Heretofore, such devices (denoted, variously, as spin injectors, spin polarizers, and spin filters) have typically offered polarization ratios having magnitudes in the approximate range of 0.01 to 0.1. The proposed devices could be useful as efficient sources of spin-polarized electron currents for research on spintronics and development of practical spintronic devices.

  13. IEC-^3He Breeder for D-^3He Satellite Systems.

    NASA Astrophysics Data System (ADS)

    Chacon, L.; Miley, G. H.

    1996-11-01

    D-^3He fusion minimizes neutrons and maximizes charged fusion products, enabling increased energy recovery efficiency by direct conversion. However, scarce ^3He terrestrial resources have deterred R&D on this alternative. Here, we explore ^3He production through Inertial Electrostatic Confinement^1 (IEC) D-breeders, which supply ^3He to FRC D-^3He satellite reactors.^2 Favorable features for the IEC breeder include simplicity, low cost, easy extraction of fusion products, and compatibility with direct conversion. The breeder-satellite system energy balance is analyzed taking the net energy gain of the overall system, Q_N, as the figure of merit. Breeding is applicable for systems where the satellite Q-value, Q_S, > the breeder Q-value, Q_B. For improved performance, i.e., for high Q_N, QS >= QB >> 1 is needed; however, lower QB values (typical of the IEC) are permissible and still offer sufficient Q_N. An economic study determined breeding produces ^3He at a cost comparable to lunar ^3He, already shown to lead to competitive power.^3 The cost of electricity (COE) for the breeder-satellite complex was compared with the ARTEMIS COE,^4 using lunar ^3He fuel: assuming one satellite (1000 MWe)/breeder (170 MWe), the ratio of the breeding system COE to the lunar mining base COE is ~ 1.2. However, economic breeding is driven by large IEC breeder powers, i.e., increased ^3He breeding rates. Thus, the COE ratio approaches unity with two or three satellites/breeder, requiring increased breeder size and power (340 MWe for 2 satellites, 510 MWe for 3 satellites). Such systems potentially provide a ``bridge'' to a future lunar ^3He economy. 1. G.H. Miley et al., Dense Z-pinches, AIP Conf. 299, AIP Press, 675-689 (1994). 2. G.H. Miley, Nucl. Instrum. Methods, A271, 197-202 (1988). 3. L.J. Wittenberg et al., Fusion Technol., 10, 167-178 (1986). 4. H. Momota et al., Fusion Technol., 21, 2307-2323 (1992).

  14. Simulations of Resonant Intraband and Interband Tunneling Spin Filters

    NASA Technical Reports Server (NTRS)

    Ting, David; Cartoixa-Soler, Xavier; McGill, T. C.; Smith, Darryl L.; Schulman, Joel N.

    2001-01-01

    This viewgraph presentation reviews resonant intraband and interband tunneling spin filters It explores the possibility of building a zero-magnetic-field spin polarizer using nonmagnetic III-V semiconductor heterostructures. It reviews the extensive simulations of quantum transport in asymmetric InAs/GaSb/AlSb resonant tunneling structures with Rashba spin splitting and proposes a. new device concept: side-gated asymmetric Resonant Interband Tunneling Diode (a-RITD).

  15. Polarization of a stored beam by spin-filtering

    NASA Astrophysics Data System (ADS)

    Augustyniak, W.; Barion, L.; Barsov, S.; Bechstedt, U.; Benati, P.; Bertelli, S.; Carassiti, V.; Chiladze, D.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Dymov, S.; Engels, R.; Erwen, W.; Fiorini, M.; Gaisser, M.; Gebel, R.; Goslaswski, P.; Grigoriev, K.; Guidoboni, G.; Kacharava, A.; Khoukaz, A.; Kulikov, A.; Kleines, H.; Langenberg, G.; Lehrach, A.; Lenisa, P.; Lomidze, N.; Lorentz, B.; Macharashvili, G.; Maier, R.; Marianski, B.; Martin, S.; Mchedlishvili, D.; Merzliakov, S.; Meshkov, I. N.; Meyer, H. O.; Mielke, M.; Mikirtychiants, M.; Mikirtychiants, S.; Nass, A.; Nekipelov, M.; Nikolaev, N.; Nioradze, M.; Oellers, D.; Papenbrock, M.; Pappalardo, L.; Pesce, A.; Polyanskiy, A.; Prasuhn, D.; Rathmann, F.; Sarkadi, J.; Smirnov, A.; Seyfarth, H.; Shmakova, V.; Statera, M.; Steffens, E.; Stein, H. J.; Stockhorst, H.; Straatman, H.; Ströher, H.; Tabidze, M.; Tagliente, G.; Thörngren-Engblom, P.; Trusov, S.; Trzcinski, A.; Valdau, Yu.; Vasiliev, A.; von Würtemberg, K. M.; Weidemann, Chr.; Wüstner, P.; Zupranski, P.

    2012-11-01

    The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. The measurement allowed the determination of the spin-dependent polarizing cross section, that compares well with the theoretical prediction from the nucleon-nucleon potential. The test confirms that spin-filtering can be adopted as a method to polarize a stored beam and that the present interpretation of the mechanism in terms of the proton-proton interaction is correct. The outcome of the experiment is of utmost importance in view of the possible application of the method to polarize a beam of stored antiprotons.

  16. Towards Polarised Antiprotons: Machine Developments for Spin-Filtering Studies

    NASA Astrophysics Data System (ADS)

    Lenisa, Paolo

    2016-02-01

    We address the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at the COSY ring in Jülich (Germany) at a beam kinetic energy of 49.3 MeV. The implementation of a low-beta insertion made it possible to achieve beam lifetimes of 8000 s in the presence of a dense polarized hydrogen storage cell target. The developed techniques can be directly applied to antiproton machines and allow for the determination of the spin-dependent pbar-p cross sections via spin-filtering.

  17. Hybrid magnetic tunnel junction/spin filter device

    SciTech Connect

    Suzuki, Y.; Nelson-Cheeseman, B.; Wong, F.; Chopdekar, R.; Arenholz, E.; Chi, Miaofang; Browning, Nigel

    2008-07-10

    Surfaces and interfaces of complex oxides materials provide a rich playground for the exploration of novel magnetic properties not found in the bulk but also the development of functional interfaces to be incorporated into applications. We have recently been able to demonstrate a new type of hybrid spin filter/ magnetic tunnel junction. Our hybrid spin-filter/magnetic-tunnel junction devices are epitaxial oxide junctions of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and Fe{sub 3}O{sub 4} electrodes with magnetic NiMn{sub 2}O{sub 4} barrier layers. Depending on whether the barrier is in a paramagnetic or ferromagnetic state, the junction exhibits magnetic tunnel junction behavior where the spin polarized conduction is dominated by the electrode-barrier interface or spin filter behavior where conduction is dominated by barrier layer magnetism.

  18. Spin filtering in a magnetized zigzag phosphorene nanoribbon

    NASA Astrophysics Data System (ADS)

    Keshtan, M. Ali M.; Esmaeilzadeh, Mahdi

    2015-12-01

    Using the Keldysh non-equilibrium Green’s function method and applying the Landauer-Büttiker formula, the spin-dependent electron transport properties of a zigzag phosphorene nanoribbon at zero temperature are studied. The depositing of two ferromagnetic strips on the edges of the nanoribbon induces exchange fields with parallel and anti-parallel configurations. An external perpendicular electric field is also applied to manipulate the spin-dependent electron conductance properties. Due to the order of the zigzag phosphorene nanoribbon edge bands near zero Fermi energy, parallel and anti-parallel configurations result in different properties. For anti-parallel configuration, spin filtering only occurs in the presence of a perpendicular electric field, while in the parallel case spin filtering takes place both in the absence and in the presence of an electric field. Although spin filtering properties are invariant against the inversion of the direction of the electric field in a parallel configuration, this inversion changes the spin filtering type for anti-parallel configurations.

  19. Controllable photo-induced spin and valley filtering in silicene

    NASA Astrophysics Data System (ADS)

    Mohammadi, Yawar; Nia, Borhan Arghavani

    2016-08-01

    We investigate theoretically the spin- and valley-dependent ballistic transport in silicene, which is assumed to be modulated by local application of a gate voltage and off-resonant circularly polarized light. We show that, due to the coupling between valley and spin degrees of freedom in silicene, the current through it is spin and valley polarized. The spin (valley) polarization can be enhanced by tuning the light intensity and the value of the perpendicular electric field, leading to perfect spin (valley) filtering for certain of their values. It is also found that the spin (valley) polarization can be inverted by reversing the perpendicular electric field (by reversing the perpendicular electric field or reversing the circular polarization of the light irradiation).

  20. Efficient spin filter using multi-terminal quantum dot with spin-orbit interaction

    PubMed Central

    2011-01-01

    We propose a multi-terminal spin filter using a quantum dot with spin-orbit interaction. First, we formulate the spin Hall effect (SHE) in a quantum dot connected to three leads. We show that the SHE is significantly enhanced by the resonant tunneling if the level spacing in the quantum dot is smaller than the level broadening. We stress that the SHE is tunable by changing the tunnel coupling to the third lead. Next, we perform a numerical simulation for a multi-terminal spin filter using a quantum dot fabricated on semiconductor heterostructures. The spin filter shows an efficiency of more than 50% when the conditions for the enhanced SHE are satisfied. PACS numbers: 72.25.Dc,71.70.Ej,73.63.Kv,85.75.-d PMID:21711500

  1. Spin manipulation in carbon nanotubes: All electrical spin filtering through spin-orbit interactions

    NASA Astrophysics Data System (ADS)

    Diniz, G. S.; Latgé, A.; Ulloa, S. E.

    2011-03-01

    Carbon nanotubes (CNTs) are known to exhibit interesting physical properties, such as metallic or insulating behavior for different chiral vectors. Application of external electric fields and the presence of spin-orbit interaction (SOI) result in modification of the energy level structure of CNTs and their conductance profiles. SOI couples spin and orbital degrees of freedom in these nanostructures, and we explore this effect in this work. We present calculations of the electronic transport of different single-wall CNTs in the presence of SOI. Our calculation uses a single-orbital tight-binding Hamiltonian representation and the equilibrium surface Green's function formalism to calculate electronic transport. We consider the effects of both Rashba and intrinsic SOIs. Our results show possible implementations of carbon nanotubes as spin filtering devices for spatially asymmetric electric fields. We further discuss the spin polarization for different CNT size, chirality, field strength, and the spatially varying fields induced by the adsorption of DNA on their surface. Supported by NSF and CAPES/Fulbright.

  2. Perpendicularly magnetized spin filtering Cu/Ni multilayers

    SciTech Connect

    Shirahata, Yasuhiro; Wada, Eiji; Itoh, Mitsuru; Taniyama, Tomoyasu

    2014-01-20

    Spin filtering at perpendicular magnetized Cu/Ni multilayer/GaAs(001) interfaces is demonstrated at remanence using optical spin orientation method. [Cu(9 nm)/Ni(t{sub Ni} nm)]{sub n} multilayers are found to show a crossover from the in-plane to out-of-plane magnetic anisotropy at the Cu/Ni bilayer repetition n = 4 and the Ni layer thickness t{sub Ni} = 3. For a perpendicularly magnetized Cu/Ni multilayer/n-GaAs(001) interface, circular polarization dependent photocurrent shows a clear hysteretic behavior under optical spin orientation conditions as a function of magnetic field out-of-plane while the bias dependence exhibits a substantial peak at a forward bias, verifying that Cu/Ni multilayers work as an efficient spin filter in the remanent state.

  3. Enhancing spin injection efficiency through half-metallic miniband conduction in a spin-filter superlattice.

    PubMed

    Yang, Yi-Hang; Li, Lin; Liu, Fen; Gao, Zhi-Wei; Miao, Guo-Xing

    2016-02-10

    We theoretically and numerically studied the band structure and spin transport of electrons subject to a superlattice structure where magnetic semiconductor layers lie between normal semiconductor layers to form periodic spin-filter tunnel barriers. In this alternately deposited superlattice structure, due to the induced periodicity of the envelope wavefunctions, there are additional allowed and forbidden energy regions established, i.e. forming minibands that are far narrower than the conventional conduction bands. The number and thickness of the stacked potential profiles can finely tune these minibands. The spin dependent potential barriers also induce spin splitting at the bottom of each miniband, which generates strongly spin-dependent miniband conduction. Most strikingly, the lowest lying miniband is 100% spin-polarized mimicking a half-metallic behavior on this conduction channel. The total transmission electron current carries thus near-perfectly polarized spin currents when the superlattice falls into suitable miniband conduction regime. This half-metallic miniband enhanced spin-filtering capability paves the way to generate highly polarized spin current without incurring exponentially increased device impedance, as usually happens when only a single spin-filter barrier is applied. PMID:26761786

  4. Enhancing spin injection efficiency through half-metallic miniband conduction in a spin-filter superlattice

    NASA Astrophysics Data System (ADS)

    Yang, Yi-Hang; Li, Lin; Liu, Fen; Gao, Zhi-Wei; Miao, Guo-Xing

    2016-02-01

    We theoretically and numerically studied the band structure and spin transport of electrons subject to a superlattice structure where magnetic semiconductor layers lie between normal semiconductor layers to form periodic spin-filter tunnel barriers. In this alternately deposited superlattice structure, due to the induced periodicity of the envelope wavefunctions, there are additional allowed and forbidden energy regions established, i.e. forming minibands that are far narrower than the conventional conduction bands. The number and thickness of the stacked potential profiles can finely tune these minibands. The spin dependent potential barriers also induce spin splitting at the bottom of each miniband, which generates strongly spin-dependent miniband conduction. Most strikingly, the lowest lying miniband is 100% spin-polarized mimicking a half-metallic behavior on this conduction channel. The total transmission electron current carries thus near-perfectly polarized spin currents when the superlattice falls into suitable miniband conduction regime. This half-metallic miniband enhanced spin-filtering capability paves the way to generate highly polarized spin current without incurring exponentially increased device impedance, as usually happens when only a single spin-filter barrier is applied.

  5. Controllable spin polarization and spin filtering in a zigzag silicene nanoribbon

    SciTech Connect

    Farokhnezhad, Mohsen Esmaeilzadeh, Mahdi Pournaghavi, Nezhat; Ahmadi, Somaieh

    2015-05-07

    Using non-equilibrium Green's function, we study the spin-dependent electron transport properties in a zigzag silicene nanoribbon. To produce and control spin polarization, it is assumed that two ferromagnetic strips are deposited on the both edges of the silicene nanoribbon and an electric field is perpendicularly applied to the nanoribbon plane. The spin polarization is studied for both parallel and anti-parallel configurations of exchange magnetic fields induced by the ferromagnetic strips. We find that complete spin polarization can take place in the presence of perpendicular electric field for anti-parallel configuration and the nanoribbon can work as a perfect spin filter. The spin direction of transmitted electrons can be easily changed from up to down and vice versa by reversing the electric field direction. For parallel configuration, perfect spin filtering can occur even in the absence of electric field. In this case, the spin direction can be changed by changing the electron energy. Finally, we investigate the effects of nonmagnetic Anderson disorder on spin dependent conductance and find that the perfect spin filtering properties of nanoribbon are destroyed by strong disorder, but the nanoribbon retains these properties in the presence of weak disorder.

  6. Interlaced spin grating for optical wave filtering

    NASA Astrophysics Data System (ADS)

    Linget, H.; Chanelière, T.; Le Gouët, J.-L.; Berger, P.; Morvan, L.; Louchet-Chauvet, A.

    2015-02-01

    Interlaced spin grating is a scheme for the preparation of spectrospatial periodic absorption gratings in an inhomogeneously broadened absorption profile. It relies on the optical pumping of atoms in a nearby long-lived ground state sublevel. The scheme takes advantage of the sublevel proximity to build large contrast gratings with unlimited bandwidth and preserved average optical depth. It is particularly suited to Tm-doped crystals in the context of classical and quantum signal processing. In this paper, we study the optical pumping dynamics at play in an interlaced spin grating and describe the corresponding absorption profile shape in an optically thick atomic ensemble. We show that, in Tm:YAG, the diffraction efficiency of such a grating can reach 18.3 % in the small-angle and 11.6 % in the large-angle configuration when the excitation is made of simple pulse pairs, considerably outperforming conventional gratings.

  7. Development of a Polarized 3He Ion Source for RHIC

    SciTech Connect

    Milner, Richard G.

    2013-01-15

    The goal of the project was to design and construct a source of polarized 3He atoms for injection into EBIS. This is the initial step in producing polarized 3He beams in RHIC in collaboration with physicists from Columbia University and Brookhaven National Laboratory. These beams can be used to probe the spin structure of the neutron in the existing RHIC complex as well as to measure precisely the Bjorken Sum Rule at a future eRHIC electron-ion collider.

  8. Spin-Filtering studies at COSY and AD

    SciTech Connect

    Nass, Alexander

    2008-02-06

    An overview on the present understanding of the methods to polarize an antiproton beam is given and the planned measurements on spin filtering at COSY and AD rings with protons and antiprotons are described. The experimental setup which is being prepared for these measurements is described and focus is given on the polarized internal target.

  9. Early Days of Superfluid ^3He: An Experimenter's View

    NASA Astrophysics Data System (ADS)

    Lee, David

    2010-03-01

    The formulation of the BCS theory led theorists to investigate possible non-S-wave pairing in liquid ^3He. Unfortunately as time went on, estimates for the pairing temperature became unattainably low. Nevertheless, the push to lower temperatures by experimentalists continued and was facilitated by the invention of the dilution refrigerator. Nuclear adiabatic demagnetization could then be used to cool liquid ^3He to ˜1 mK as demonstrated by Goodkind. An alternate approach, suggested by Pomeranchuk, involved adiabatic compression of liquid ^3He into the solid phase. Efforts to develop this technique at the Kapitza Institute, La Jolla and Cornell achieved success in demonstrating cooling of mixtures of liquid and solid ^3He to ˜ 1 mK following dilution refrigerator pre-cooling. Although there was great pessimism regarding the possible observation of pairing in liquid ^3He, the unsettled problem of magnetic ordering in solid ^3He beckoned. Ultimately two phase transition along the melting curve were observed by Osheroff et al at Cornell. Although first associated with solid ^3He, extensive NMR studies showed them to be two new phases of liquid ^3He. A brief history of experiments at various laboratories following the discovery is given, along with early interpretations given by Anderson and Morel and Balian and Werthamer. The key role of Leggett's spin dynamics is also discussed.

  10. An extended Kalman filter for spinning spacecraft attitude estimation

    NASA Technical Reports Server (NTRS)

    Baker, David F.

    1991-01-01

    An extended Kalman filter for real-time ground attitude estimation of a gyro-less spinning spacecraft was developed and tested. The filter state vector includes the angular momentum direction, phase angle, inertial nutation angle, and inertial and body nutation rates. The filter solves for the nutating three-axis attitude and accounts for effects due to principle axes offset from the body axes. The attitude is propagated using the kinematics of a rigid body symmetric about the principle spin axis; disturbance torques are assumed to be small. Filter updates consist only of the measured angles between celestial objects (Sun, Earth, etc.) and the nominal spin axis, and the times these angles were measured. Both simulated data and real data from the Dynamics Explorer -A (DE-A) spacecraft were used to test the filter; the results are presented. Convergence was achieved rapidly from a wide range of a priori state estimates, and sub-degree accuracy was attained. Systematic errors affecting the solution accuracy are discussed, as are the results of an attempt to solve for sensor measurement angle biases in the state vector.

  11. High spin-filter efficiency and Seebeck effect through spin-crossover iron-benzene complex.

    PubMed

    Yan, Qiang; Zhou, Liping; Cheng, Jue-Fei; Wen, Zhongqian; Han, Qin; Wang, Xue-Feng

    2016-04-21

    Electronic structures and coherent quantum transport properties are explored for spin-crossover molecule iron-benzene Fe(Bz)2 using density functional theory combined with non-equilibrium Green's function. High- and low-spin states are investigated for two different lead-molecule junctions. It is found that the asymmetrical T-shaped contact junction in the high-spin state behaves as an efficient spin filter while it has a smaller conductivity than that in the low-spin state. Large spin Seebeck effect is also observed in asymmetrical T-shaped junction. Spin-polarized properties are absent in the symmetrical H-shaped junction. These findings strongly suggest that both the electronic and contact configurations play significant roles in molecular devices and metal-benzene complexes are promising materials for spintronics and thermo-spintronics. PMID:27389217

  12. High spin-filter efficiency and Seebeck effect through spin-crossover iron-benzene complex

    NASA Astrophysics Data System (ADS)

    Yan, Qiang; Zhou, Liping; Cheng, Jue-Fei; Wen, Zhongqian; Han, Qin; Wang, Xue-Feng

    2016-04-01

    Electronic structures and coherent quantum transport properties are explored for spin-crossover molecule iron-benzene Fe(Bz)2 using density functional theory combined with non-equilibrium Green's function. High- and low-spin states are investigated for two different lead-molecule junctions. It is found that the asymmetrical T-shaped contact junction in the high-spin state behaves as an efficient spin filter while it has a smaller conductivity than that in the low-spin state. Large spin Seebeck effect is also observed in asymmetrical T-shaped junction. Spin-polarized properties are absent in the symmetrical H-shaped junction. These findings strongly suggest that both the electronic and contact configurations play significant roles in molecular devices and metal-benzene complexes are promising materials for spintronics and thermo-spintronics.

  13. Toward polarized antiprotons: Machine development for spin-filtering experiments

    NASA Astrophysics Data System (ADS)

    Weidemann, C.; Rathmann, F.; Stein, H. J.; Lorentz, B.; Bagdasarian, Z.; Barion, L.; Barsov, S.; Bechstedt, U.; Bertelli, S.; Chiladze, D.; Ciullo, G.; Contalbrigo, M.; Dymov, S.; Engels, R.; Gaisser, M.; Gebel, R.; Goslawski, P.; Grigoriev, K.; Guidoboni, G.; Kacharava, A.; Kamerdzhiev, V.; Khoukaz, A.; Kulikov, A.; Lehrach, A.; Lenisa, P.; Lomidze, N.; Macharashvili, G.; Maier, R.; Martin, S.; Mchedlishvili, D.; Meyer, H. O.; Merzliakov, S.; Mielke, M.; Mikirtychiants, M.; Mikirtychiants, S.; Nass, A.; Nikolaev, N. N.; Oellers, D.; Papenbrock, M.; Pesce, A.; Prasuhn, D.; Retzlaff, M.; Schleichert, R.; Schröer, D.; Seyfarth, H.; Soltner, H.; Statera, M.; Steffens, E.; Stockhorst, H.; Ströher, H.; Tabidze, M.; Tagliente, G.; Engblom, P. Thörngren; Trusov, S.; Valdau, Yu.; Vasiliev, A.; Wüstner, P.

    2015-02-01

    The paper describes the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at a beam kinetic energy of 49.3 MeV in COSY. The implementation of a low-β insertion made it possible to achieve beam lifetimes of τb=8000 s in the presence of a dense polarized hydrogen storage-cell target of areal density dt=(5.5 ±0.2 )×1 013 atoms /cm2 . The developed techniques can be directly applied to antiproton machines and allow the determination of the spin-dependent p ¯p cross sections via spin filtering.

  14. Kalman Filter Estimation of Spinning Spacecraft Attitude using Markley Variables

    NASA Technical Reports Server (NTRS)

    Sedlak, Joseph E.; Harman, Richard

    2004-01-01

    There are several different ways to represent spacecraft attitude and its time rate of change. For spinning or momentum-biased spacecraft, one particular representation has been put forward as a superior parameterization for numerical integration. Markley has demonstrated that these new variables have fewer rapidly varying elements for spinning spacecraft than other commonly used representations and provide advantages when integrating the equations of motion. The current work demonstrates how a Kalman filter can be devised to estimate the attitude using these new variables. The seven Markley variables are subject to one constraint condition, making the error covariance matrix singular. The filter design presented here explicitly accounts for this constraint by using a six-component error state in the filter update step. The reduced dimension error state is unconstrained and its covariance matrix is nonsingular.

  15. On 3He bolometer systems

    NASA Technical Reports Server (NTRS)

    Houck, J. R.

    1983-01-01

    A 3He cryostat which was constructed to cool a germanium bolometer for use as an infrared detector at submillimeter wavelength is discussed. The system had better sensitivity than any other existing system for these wavelengths; the system could be improved if better optical coupling could be achieved between the bolometer and the incoming photon stream. Considerable effort was expended to improve this coupling. Even the best results however, fell short of an ideal system by a factor of nearly 5 in coupling efficiency.

  16. A multipurpose 3He refrigerator

    NASA Astrophysics Data System (ADS)

    Pizzo, L.; Dall'Oglio, G.; Martinis, L.; Sabbatini, L.

    2006-10-01

    We introduce a mini 3He refrigerator, operating at ˜300 mK starting from 4.2 K without pumping on the main 4He bath. The innovative idea is that the present one is suitable for a very fast operation; for its use, it is sufficient a storage 4He Dewar. In this way we drastically reduce the time required to cool it down, because there is no need for a classic cryostat. This prototype is particularly aimed for all those operations in which it is necessary to test a large number of samples that do not require long duration measurements at low temperature.

  17. Ultrasensitive 3He magnetometer for measurements of high magnetic fields

    NASA Astrophysics Data System (ADS)

    Nikiel, Anna; Blümler, Peter; Heil, Werner; Hehn, Manfred; Karpuk, Sergej; Maul, Andreas; Otten, Ernst; Schreiber, Laura M.; Terekhov, Maxim

    2014-11-01

    We describe a 3He magnetometer capable to measure high magnetic fields ( B> 0.1 T) with a relative accuracy of better than 10-12. Our approach is based on the measurement of the free induction decay of gaseous, nuclear spin polarized 3He following a resonant radio frequency pulse excitation. The measurement sensitivity can be attributed to the long coherent spin precession time T2 ∗ being of order minutes which is achieved for spherical sample cells in the regime of "motional narrowing" where the disturbing influence of field inhomogeneities is strongly suppressed. The 3He gas is spin polarized in situ using a new, non-standard variant of the metastability exchange optical pumping. We show that miniaturization helps to increase T2 ∗ further and that the measurement sensitivity is not significantly affected by temporal field fluctuations of order 10-4.

  18. Rubidium Optical Pumping for an Electron Spin Filter

    NASA Astrophysics Data System (ADS)

    Norrgard, Eric

    2010-03-01

    Our group is designing a novel polarized electron source based on spin exchange between an incident beam of electrons and an optically-pumped rubidium vapor target [1,2]. An overview of the spin filter design will be provided. I will then discuss optical pumping of rubidium and techniques for measuring spin polarization. An anomalous Rb polarization reversal detected when varying the wavelength of a pump laser with a spectral width of about 6 percent of the absorption profile of the Rb D2 transition width over the absorption profile will be examined. In the rubidium electron spin filter, viable spin exchange is thought to occur in the immediate vicinity of the exit aperture of the optical pumping region. Therefore, optical techniques for mapping the spatial dependence of a pumped Rb sample will be discussed, and measurements of Rb polarization throughout the optically-pump region will be presented.[4pt] [1] H. Batelaan et al., Phys. Rev. Lett., 82, 4216 (1999).[0pt] [2] M.A. Rosenberry, J.P. Reyes, D. Tupa, T.J. Gay Phys. Rev. A 75, 023401 (2007).

  19. Hard Photodisintegration of 3He

    NASA Astrophysics Data System (ADS)

    Granados, Carlos

    2011-02-01

    Large angle photodisintegration of two nucleons from the 3He nucleus is studied within the framework of the hard rescattering model (HRM). In the HRM the incoming photon is absorbed by one nucleon's valence quark that then undergoes a hard rescattering reaction with a valence quark from the second nucleon producing two nucleons emerging at large transverse momentum . Parameter free cross sections for pp and pn break up channels are calculated through the input of experimental cross sections on pp and pn elastic scattering. The calculated cross section for pp breakup and its predicted energy dependency are in good agreement with recent experimental data. Predictions on spectator momentum distributions and helicity transfer are also presented.

  20. Macroscopic quantum tunnelling in spin filter ferromagnetic Josephson junctions.

    PubMed

    Massarotti, D; Pal, A; Rotoli, G; Longobardi, L; Blamire, M G; Tafuri, F

    2015-01-01

    The interfacial coupling of two materials with different ordered phases, such as a superconductor (S) and a ferromagnet (F), is driving new fundamental physics and innovative applications. For example, the creation of spin-filter Josephson junctions and the demonstration of triplet supercurrents have suggested the potential of a dissipationless version of spintronics based on unconventional superconductivity. Here we demonstrate evidence for active quantum applications of S-F-S junctions, through the observation of macroscopic quantum tunnelling in Josephson junctions with GdN ferromagnetic insulator barriers. We show a clear transition from thermal to quantum regime at a crossover temperature of about 100 mK at zero magnetic field in junctions, which present clear signatures of unconventional superconductivity. Following previous demonstration of passive S-F-S phase shifters in a phase qubit, our result paves the way to the active use of spin filter Josephson systems in quantum hybrid circuits. PMID:26054495

  1. Macroscopic quantum tunnelling in spin filter ferromagnetic Josephson junctions

    PubMed Central

    Massarotti, D.; Pal, A.; Rotoli, G.; Longobardi, L.; Blamire, M. G.; Tafuri, F.

    2015-01-01

    The interfacial coupling of two materials with different ordered phases, such as a superconductor (S) and a ferromagnet (F), is driving new fundamental physics and innovative applications. For example, the creation of spin-filter Josephson junctions and the demonstration of triplet supercurrents have suggested the potential of a dissipationless version of spintronics based on unconventional superconductivity. Here we demonstrate evidence for active quantum applications of S-F-S junctions, through the observation of macroscopic quantum tunnelling in Josephson junctions with GdN ferromagnetic insulator barriers. We show a clear transition from thermal to quantum regime at a crossover temperature of about 100 mK at zero magnetic field in junctions, which present clear signatures of unconventional superconductivity. Following previous demonstration of passive S-F-S phase shifters in a phase qubit, our result paves the way to the active use of spin filter Josephson systems in quantum hybrid circuits. PMID:26054495

  2. Electron-Spin Filters Based on the Rashba Effect

    NASA Technical Reports Server (NTRS)

    Ting, David Z.-Y.; Cartoixa, Xavier; McGill, Thomas C.; Moon, Jeong S.; Chow, David H.; Schulman, Joel N.; Smith, Darryl L.

    2004-01-01

    Semiconductor electron-spin filters of a proposed type would be based on the Rashba effect, which is described briefly below. Electron-spin filters more precisely, sources of spin-polarized electron currents have been sought for research on, and development of, the emerging technological discipline of spintronics (spin-based electronics). There have been a number of successful demonstrations of injection of spin-polarized electrons from diluted magnetic semiconductors and from ferromagnetic metals into nonmagnetic semiconductors. In contrast, a device according to the proposal would be made from nonmagnetic semiconductor materials and would function without an applied magnetic field. The Rashba effect, named after one of its discoverers, is an energy splitting, of what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. The present proposal evolved from recent theoretical studies that suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling. Accordingly, a device according to the proposal would be denoted an asymmetric resonant interband tunneling diode [a-RITD]. An a-RITD could be implemented in a variety of forms, the form favored in the proposal being a double-barrier heterostructure containing an asymmetric quantum well. It is envisioned that a-RITDs would be designed and fabricated in the InAs/GaSb/AlSb material system for several reasons: Heterostructures in this material system are strong candidates for pronounced Rashba spin splitting because InAs and GaSb exhibit large spin-orbit interactions and because both InAs and GaSb would be available for the construction of highly asymmetric

  3. Role of magnetic anisotropy in spin-filter junctions

    SciTech Connect

    Chopdekar, R.V.; Wong, F.; Nelson-Cheeseman, B.B.; Liberati, M.; Arenholz, E.; Suzuki, Y.

    2011-01-10

    We have fabricated oxide-based spin-filter junctions in which we demonstrate that magnetic anisotropy can be used to tune the transport behavior of spin-filter junctions. We have demonstrated spin-filtering behavior in La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/CoCr{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} and La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/MnCr{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} junctions where the interface anisotropy plays a significant role in determining transport behavior. Detailed studies of chemical and magnetic structure at the interfaces indicate that abrupt changes in magnetic anisotropy across the nonisostructural interface is the cause of the significant suppression of junction magnetoresistance in junctions with MnCr{sub 2}O{sub 4} barrier layers.

  4. Spin-filter and spin-gapless semiconductors: The case of Heusler compounds

    NASA Astrophysics Data System (ADS)

    Galanakis, I.; Özdoǧan, K.; Şaşıoǧlu, E.

    2016-05-01

    We review our recent first-principles results on the inverse Heusler compounds and the ordered quaternary (also known as LiMgPdSn-type) Heusler compounds. Among these two subfamilies of the full-Heusler compounds, several have been shown to be magnetic semiconductors. Such material can find versatile applications, e.g. as spin-filter materials in magnetic tunnel junctions. Finally, a special case are the spin-gapless semiconductors, where the energy gap at the Fermi level for the one spin-direction is almost vanishing, offering novel functionalities in spintronic/magnetoelectronic devices.

  5. A spin filter transistor made of topological Weyl semimetal

    SciTech Connect

    Shi, Zhangsheng; Wang, Maoji; Wu, Jiansheng

    2015-09-07

    Topological boundary states (TBSs) in Weyl semimetal (WSM) thin film can induce tunneling. Such TBSs are spin polarized inducing spin-polarized current, which can be used to build a spin-filter transistor (SFT) in spintronics. The WSM thin film can be viewed as a series of decoupled quantum anomalous Hall insulator (QAHI) wires connected in parallel, so compared with the proposed SFT made of QAHI nanowire, this SFT has a broader working energy region and easier to be manipulated. And within a narrow region outside this energy domain, the 2D WSM is with very low conductance, so it makes a good on/off switch device with controllable chemical potential induced by liquid ion gate. We also construct a loop device made of 2D WSM with inserted controllable flux to control the polarized current.

  6. A spin filter transistor made of topological Weyl semimetal

    NASA Astrophysics Data System (ADS)

    Shi, Zhangsheng; Wang, Maoji; Wu, Jiansheng

    2015-09-01

    Topological boundary states (TBSs) in Weyl semimetal (WSM) thin film can induce tunneling. Such TBSs are spin polarized inducing spin-polarized current, which can be used to build a spin-filter transistor (SFT) in spintronics. The WSM thin film can be viewed as a series of decoupled quantum anomalous Hall insulator (QAHI) wires connected in parallel, so compared with the proposed SFT made of QAHI nanowire, this SFT has a broader working energy region and easier to be manipulated. And within a narrow region outside this energy domain, the 2D WSM is with very low conductance, so it makes a good on/off switch device with controllable chemical potential induced by liquid ion gate. We also construct a loop device made of 2D WSM with inserted controllable flux to control the polarized current.

  7. Electrically-manipulable spin filter based on a novel magnetic nanostructure

    NASA Astrophysics Data System (ADS)

    Liu, Xu-Hui; Gong, Yan-Jun; Li, Xiao-Wu

    2016-03-01

    In order to achieve a controllable spin-polarized source, we have applied a transverse electric field to a spin filter based on a novel magnetic nanostructure with zero average magnetic field. We have analytically calculated the transmission coefficient, conductance and spin polarization for electrons to transit the device in the presence of a transverse electric field. The results demonstrate that the transmission, the conductance and the spin polarization vary sensitively with the electric field. It is shown that the performance of the spin filter can be manipulated expediently by adjusting the transverse electric field. Thus, the spin filter can be utilized as an electrically controllable spin-polarized source for spintronics applications.

  8. Perfect spin filtering by symmetry in molecular junctions

    NASA Astrophysics Data System (ADS)

    Li, Dongzhe; Dappe, Yannick J.; Smogunov, Alexander

    2016-05-01

    Obtaining highly spin-polarized currents in molecular junctions is crucial and important for nanoscale spintronics devices. Motivated by our recent symmetry-based theoretical argument for complete blocking of one spin conductance channel in model molecular junctions [A. Smogunov and Y. J. Dappe, Nano Lett. 15, 3552 (2015), 10.1021/acs.nanolett.5b01004], we explore the generality of the proposed mechanism and the degree of achieved spin-polarized current for realistic molecular junctions made of various ferromagnetic electrodes (Ni, Co, Fe) connected by different molecules (quaterthiophene or p -quaterphenyl). A simple analysis of the spin-resolved local density of states of a free electrode allowed us to identify the Fe(110) as the most optimal electrode, providing perfect spin filtering and high conductance at the same time. These results are confirmed by ab initio quantum transport calculations and are similar to those reported previously for model junctions. It is found, moreover, that the distortion of the p -quaterphenyl molecule plays an important role, reducing significantly the overall conductance.

  9. Direct detection of spin chemical potential shift through spin filtering effect

    NASA Astrophysics Data System (ADS)

    Miao, Guoxing; Moodera, Jagadeesh

    2010-03-01

    Spin filtering (SF) effect is a unique way to generate highly spin-polarized tunnel currents from nonmagnetic electrodes. Magnetic tunnel junctions based on pure SF effect have been realized recently [1] as a clear demonstration of principle for the spin manipulation through SF effect. The next challenge is the readout of spin information. In this work, we present the direct detection of the spin chemical potential shift in an Al nano cluster sandwiched between two SF EuS tunnel barriers. The spin channels are split by depositing Al directly onto EuS, and the indirect exchange interaction between the Al conduction electrons and the localized Eu 4f electrons gives rise to an effective Zeeman splitting with the strength of a few mV. EuS on the readout side is isolated from the Al clusters with a natural Al2O3 barrier. In a vertical measurement geometry with no transport current, we directly detected the spin dependent voltage levels by aligning the detection SF barrier parallel or antiparallel to the first SF barrier, corresponding to the equilibrium up- and down-spin chemical potentials. A simple analysis treating the barriers as a set of resistors revealed that the observed voltage difference is the actual chemical potential shift modulated by the SF efficiency.[4pt] [1] G.X. Miao, M. Muller, J.S. Moodera,PRL102,076601(2009)

  10. 3He Films as Model Strongly Correlated Fermion Systems

    SciTech Connect

    Neumann, Michael; Casey, Andrew; Nyeki, Jan; Cowan, Brian; Saunders, John

    2006-09-07

    Helium films on graphite are atomically layered. This allows a wide variety of studies of strong correlations in two dimensions with density as a continuously tunable parameter. Studies of a monolayer of 3He adsorbed on graphite plated by a bi-layer of HD find a divergence of effective mass with increasing density, corresponding to a Mott-Hubbard transition between a 2D Fermi liquid and a quantum spin liquid phase. While the Fermi liquid survives in 2D, non-Fermi liquid features remain at finite T, recent theories find that this correction arises from the spin component of the backscattering amplitude. In another experiment a 3He film is grown on graphite plated by a bi-layer of 3He. The first 3He layer only solidifies in the presence of an overlayer. However in the regime in which the system comprises a 3He fluid bilayer, we observe a striking maximum in the temperature dependence of both heat capacity and magnetization. This feature is driven towards T = 0 with increasing film coverage, suggestive of a quantum critical point. Well below the maximum a linear temperature dependence of the heat capacity is recovered; the coverage dependence of the effective mass identifies a (bandwidth driven) Mott-Hubbard transition at 9.8 nm-2.

  11. Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junctions

    PubMed Central

    Tang, Y. -H.; Chu, F. -C.; Kioussis, Nicholas

    2015-01-01

    We predict a giant field-like spin torque, , in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SF’s exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both ‘reading’ and ‘writing’ processes which require lower critical current densities and faster writing and reading speeds. PMID:26095146

  12. Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junctions.

    PubMed

    Tang, Y-H; Chu, F-C; Kioussis, Nicholas

    2015-01-01

    We predict a giant field-like spin torque, T[symbol in text], in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SF's exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of T[symbol in text] via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both 'reading' and 'writing' processes which require lower critical current densities and faster writing and reading speeds. PMID:26095146

  13. Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Tang, Y.-H.; Chu, F.-C.; Kioussis, Nicholas

    2015-06-01

    We predict a giant field-like spin torque, , in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SF’s exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both ‘reading’ and ‘writing’ processes which require lower critical current densities and faster writing and reading speeds.

  14. Progress in Polarized 3He Ion Source at RCNP

    SciTech Connect

    Tanaka, M.; Takahashi, Y.; Shimoda, T.; Yasui, S.; Yosoi, M.; Takahisa, K.; Shimakura, N.; Plis, Yu. A.; Donets, E. D.

    2007-06-13

    A long history on the polarized 3He ion source developed at RCNP is presented. We started with an 'OPPIS' (Optical Pumping Polarized Ion Source) and later found the fundamental difficulties in the OPPIS. To overcome them an 'EPPIS' (Electron Pumping Polarized Ion Source) was proposed and its validity was experimentally proven. However, a serious technical disadvantage was also found in the EPPIS. To avoid this disadvantage we proposed a new concept, 'SEPIS' (Spin Exchange Polarized Ion Source), which uses an enhanced spin-exchange cross section theoretically expected at low 3He+ incident energies in the 3He+ + Rb system. Next, we describe the present status of the SEPIS development: construction of a bench test device allowing the measurements of not only the spin-exchange cross sections {sigma}se but also the electron capture cross sections {sigma}ec for the 3He+ + Rb system. The latest experimental data on {sigma}ec are presented and compared with other previous experimental data and the theoretical calculations.Finally, a design study of the SEPIS for practical use in nuclear (cyclotron) and particle physics (synchrotron) is shortly mentioned.

  15. The influence of restricted geometry of diamagnetic nanoporous media on 3He relaxation

    NASA Astrophysics Data System (ADS)

    Alakshin, E. M.; Gazizulin, R. R.; Zakharov, M. Yu.; Klochkov, A. V.; Morozov, E. V.; Salikhov, T. M.; Safin, T. R.; Safiullin, K. R.; Tagirov, M. S.; Shabanova, O. B.

    2015-01-01

    This is an experimental study of the spin kinetics of 3He in contact with diamagnetic samples of inverse opals SiO2, and LaF3 nanopowder. It is demonstrated that the nuclear magnetic relaxation of the absorbed 3He occurs due to the modulation of dipole-dipole interaction by the quantum motion in the two-dimensional film. It is found that the relaxation of liquid 3He occurs through a spin diffusion to the absorption layer, and that the restricted geometry of diamagnetic nanoporous media has an influence on the 3He relaxation.

  16. Light-Front Dynamics and the {{3He}} Spectral Function

    NASA Astrophysics Data System (ADS)

    Pace, Emanuele; Del Dotto, Alessio; Kaptari, Leonid; Rinaldi, Matteo; Salmé, Giovanni; Scopetta, Sergio

    2016-07-01

    Two topics are presented. The first one is a novel approach for a Poincaré covariant description of nuclear dynamics based on light-front Hamiltonian dynamics. The key quantity is the light-front spectral function, where both normalization and momentum sum rule can be satisfied at the same time. Preliminary results are discussed for an initial analysis of the role of relativity in the EMC effect in {{3He}}. A second issue, very challenging, is considered in a non-relativistic framework, namely a distorted spin-dependent spectral function for {{3He}} in order to take care of the final state interaction between the observed pion and the remnant in semi-inclusive deep inelastic electron scattering off polarized {{3He}}. The generalization of the analysis within the light-front dynamics is outlined.

  17. Polarized {sup 3}He gas compression system using metastability-exchange optical pumping

    SciTech Connect

    Hussey, D.S.; Rich, D.R.; Belov, A.S.; Tong, X.; Yang, H.; Bailey, C.; Keith, C.D.; Hartfield, J.; Hall, G.D.R.; Black, T.C.; Snow, W.M.; Gentile, T.R.; Chen, W.C.; Jones, G.L.; Wildman, E.

    2005-05-15

    Dense samples (10-100 bar cm) of nuclear spin polarized {sup 3}He are utilized in high energy physics, neutron scattering, atomic physics, and magnetic resonance imaging. Metastability exchange optical pumping can rapidly produce high {sup 3}He polarizations ({approx_equal}80%) at low pressures (few mbar). We describe a polarized {sup 3}He gas compressor system which accepts 0.26 bar l h{sup -1} of {sup 3}He gas polarized to 70% by a 4 W neodymium doped lanthanum magnesium hexaluminate (Nd:LMA) laser and compresses it into a 5 bar cm target with final polarization of 55%. The spin relaxation rates of the system's components have been measured using nuclear magnetic resonance and a model of the {sup 3}He polarization loss based on the measured relaxation rates and the gas flow is in agreement with a {sup 3}He polarization measurement using neutron transmission.

  18. Lattice Relaxation of 4He with 3He Impurities: NMR Studies

    NASA Astrophysics Data System (ADS)

    Candela, D.; Huan, C.; Kim, S. S.; Yin, L.; Xia, J. S.; Sullivan, N. S.

    2014-12-01

    Measurements of the 3He nuclear spin relaxation times of dilute 3He impurities in solid 4He have been used to explore the unusual dynamics of solid 4He at low temperatures. The 3He impurities move through the lattice by quantum mechanical exchange with neighboring 4He atoms. Because of the larger zero point motion of the 3He atoms, there is an appreciable lattice distortion that accompanies the tunneling 3 He atom and the tunneling motion depends on the elastic properties of the 4He lattice. This motion modulates the 3He-3He nuclear dipole- dipole interactions and thus determines the NMR relaxation rates. We compare the observed temperature dependence of the NMR relaxation rates with that expected from the measurements of the shear modulus by Syshchenko et al. [Phys. Rev. Lett. 104, 195301 (2009)].

  19. DNP for polarizing liquid {sup 3}He

    SciTech Connect

    Uemtasu, H.; Iwata, T.; Kato, S.; Michigami, T.; Ohizumi, S.; Shishido, T.; Tanaka, A.; Toyama, K.; Tajima, Y.; Yoshida, H. Y.; Kuriyama, N.

    2008-02-06

    Using DNP with zeolite powders and TEMPO, we have developed a method to enhance polarization of liquid {sup 3}He. At magnetic field of 2.5 T and a temperature of around 1.5 K, we have obatined polarization enhancement of liquid {sup 3}He, 2.34 and -1.59 for positive and negative enhancements, respectively.

  20. Electrically tunable spin filtering for electron tunneling between spin-resolved quantum Hall edge states and a quantum dot

    SciTech Connect

    Kiyama, H. Fujita, T.; Teraoka, S.; Oiwa, A.; Tarucha, S.

    2014-06-30

    Spin filtering with electrically tunable efficiency is achieved for electron tunneling between a quantum dot and spin-resolved quantum Hall edge states by locally gating the two-dimensional electron gas (2DEG) leads near the tunnel junction to the dot. The local gating can change the potential gradient in the 2DEG and consequently the edge state separation. We use this technique to electrically control the ratio of the dot–edge state tunnel coupling between opposite spins and finally increase spin filtering efficiency up to 91%, the highest ever reported, by optimizing the local gating.

  1. First result from the magic-PASTIS using large 3He SEOP-polarized GE180 doughnut cell

    NASA Astrophysics Data System (ADS)

    Salhi, Zahir; Babcock, Earl; Gainov, Ramil; Bussmann, Klaus; Kaemmerling, Hans; Pistel, Patrick; Russina, Margarita; Ioffe, Alexander

    2016-04-01

    We report on the first results of the newly proposed and prototyped PASTIS coil set, enabling for XYZ polarization analysis on the future thermal time-of flight spectrometers. Our setup uses a wide-angle banana shaped 3He Neutron Spin Filter cell (NSF) to cover a large range of scattering solid angle. The design assures relative magnetic field gradients < 10-3 cm-1 and large solid angle areas not interrupted by either coils or supports. In the vertical direction nearly 40° are open and the blind spots in the horizontal scattering plane comprise only 3° in 180° due to the square X and Y compensation coils. We present the first results of the field mapping and relaxations time measurements using a large 3He SEOP polarized GE180 doughnut cell.

  2. Enhancement of Magnetization in Liquid 3He at Aerogel Interface

    NASA Astrophysics Data System (ADS)

    Fukui, A.; Kondo, K.; Kato, C.; Obara, K.; Yano, H.; Ishikawa, O.; Hata, T.

    2013-05-01

    A novel feature of condensate state in liquid 3He is predicted theoretically, which consists of spin triplet s-wave Cooper pairs (Higashitani et al. in J. Low. Temp. Phys. 155:83-97, 2009). Such a spin triplet s-wave state will appear inside aerogel near the surface boundary contacting with superfluid 3He-B, and the enhancement of magnetization due to s-wave state is theoretically expected (Nagato et al. in J. Phys. Soc. Jpn. 78:123603, 2009; Higashitani et al. in Phys. Rev. B 85:024524, 2012). In order to detect this proximity effect, we made the interface in columnar glass tube which coated with 2.5 layer 4He, and set a saddle shape NMR coil very near the interface. At 7 bar, we found that superfluidity in liquid 3He inside aerogel never occurred, even at considerably low temperatures. At 24 bar below T/ T c =0.392, we observed no decrease of magnetization with decreasing temperatures. This phenomenon might be due to spin triplet s-wave Cooper pairs.

  3. Large spin-filtering effect in Ti-doped defective zigzag graphene nanoribbon.

    PubMed

    Tawfik, Sherif Abdulkader; Cui, X Y; Ringer, S P; Stampfl, C

    2016-06-28

    Through first-principles calculations using the nonequilibrium Green's function formalism together with density functional theory, we study the conductance of double-vacancy zigzag graphene nanoribbons doped with four transition metal atoms Ti, V, Cr and Fe. We show that Ti doping induces large spin-filtering with an efficiency in excess of 90% for bias voltages below 0.5 V, while the other metal adatoms do not induce large spin filtering. This is despite the fact that the Ti dopant possesses small spin moment, while large moments reside on V, Cr and Fe dopants. Our analysis shows that the suppression of transmission in the spin-down channel in the Ti-doped graphene nanoribbon, thus the large spin filtering efficiency, is due to transmission anti-resonance arising from destructive quantum interference. These findings suggest that the decoration of graphene with titanium, and possibly other transition metals, can act as effective spin filters for nanospintronic applications. PMID:27252042

  4. Spin filter effects in an Aharonov-Bohm ring with double quantum dots under general Rashba spin-orbit interactions

    NASA Astrophysics Data System (ADS)

    Kondo, Kenji

    2016-01-01

    Many researchers have reported on spin filters using linear Rashba spin-orbit interactions (SOI). However, spin filters using square and cubic Rashba SOIs have not yet been reported. We consider that this is because the Aharonov-Casher (AC) phases acquired under square and cubic Rashba SOIs are ambiguous. In this study, we try to derive the AC phases acquired under square and cubic Rashba SOIs from the viewpoint of non-Abelian SU(2) gauge theory. These AC phases can be derived successfully from the non-Abelian SU(2) gauge theory without the completing square methods. Using the results, we investigate the spin filtering in a double quantum dot (QD) Aharonov-Bohm (AB) ring under linear, square, and cubic Rashba SOIs. This AB ring consists of elongated QDs and quasi-one-dimensional quantum nanowires under an external magnetic field. The spin transport is investigated from the left nanowire to the right nanowire in the above structure within the tight-binding approximation. In particular, we focus on the difference of spin filtering among linear, square, and cubic Rashba SOIs. The calculation is performed for the spin polarization by changing the penetrating magnetic flux for the AB ring subject to linear, square, and cubic Rashba SOIs. It is found that perfect spin filtering is achieved for all of the Rashba SOIs. This result indicates that this AB ring under general Rashba SOIs can be a promising device for spin current generation. Moreover, the AB rings under general Rashba SOIs behave in totally different ways in response to penetrating magnetic flux, which is attributed to linear, square, and cubic behaviors in the in-plane momentum. This result enables us to make a clear distinction between linear, square, and cubic Rashba SOIs according to the peak position of the perfect spin filtering.

  5. Non-equilibrium tunneling in zigzag graphene nanoribbon break-junction results in spin filtering

    NASA Astrophysics Data System (ADS)

    Jiang, Liming; Qiu, Wanzhi; Sharafat Hossain, Md; Al-Dirini, Feras; Evans, Robin; Skafidas, Efstratios

    2016-02-01

    Spintronic devices promise new faster and lower energy-consumption electronic systems. Graphene, a versatile material and candidate for next generation electronics, is known to possess interesting spintronic properties. In this paper, by utilizing density functional theory and non-equilibrium green function formalism, we show that Fano resonance can be generated by introducing a break junction in a zigzag graphene nanoribbon (ZGNR). Using this effect, we propose a new spin filtering device that can be used for spin injection. Our theoretical results indicate that the proposed device could achieve high spin filtering efficiency (over 90%) at practical fabrication geometries. Furthermore, our results indicate that the ZGNR break junction lattice configuration can dramatically affect spin filtering efficiency and thus needs to be considered when fabricating real devices. Our device can be fabricated on top of spin transport channel and provides good integration between spin injection and spin transport.

  6. A new generation of 3He refrigerators

    NASA Astrophysics Data System (ADS)

    Graziani, A.; DalĺOglio, G.; Martinis, L.; Pizzo, L.; Sabbatini, L.

    2003-12-01

    The characteristics and performance of a new class of 3He refrigerators are discussed. We introduce a 3He refrigerator, which allows a temperature of 296 m K to be reached with a starting point of 4.2 K, without pumping on the main 4He bath. The operating principle is based on the single-expansion helium liquefier: gas cooling by isothermal compression and adiabatic expansion.

  7. Inversion of Spin Signal and Spin Filtering in Ferromagnet|Hexagonal Boron Nitride-Graphene van der Waals Heterostructures

    PubMed Central

    Kamalakar, M. Venkata; Dankert, André; Kelly, Paul J.; Dash, Saroj P.

    2016-01-01

    Two dimensional atomically thin crystals of graphene and its insulating isomorph hexagonal boron nitride (h-BN) are promising materials for spintronic applications. While graphene is an ideal medium for long distance spin transport, h-BN is an insulating tunnel barrier that has potential for efficient spin polarized tunneling from ferromagnets. Here, we demonstrate the spin filtering effect in cobalt|few layer h-BN|graphene junctions leading to a large negative spin polarization in graphene at room temperature. Through nonlocal pure spin transport and Hanle precession measurements performed on devices with different interface barrier conditions, we associate the negative spin polarization with high resistance few layer h-BN|ferromagnet contacts. Detailed bias and gate dependent measurements reinforce the robustness of the effect in our devices. These spintronic effects in two-dimensional van der Waals heterostructures hold promise for future spin based logic and memory applications. PMID:26883717

  8. Inversion of Spin Signal and Spin Filtering in Ferromagnet|Hexagonal Boron Nitride-Graphene van der Waals Heterostructures.

    PubMed

    Kamalakar, M Venkata; Dankert, André; Kelly, Paul J; Dash, Saroj P

    2016-01-01

    Two dimensional atomically thin crystals of graphene and its insulating isomorph hexagonal boron nitride (h-BN) are promising materials for spintronic applications. While graphene is an ideal medium for long distance spin transport, h-BN is an insulating tunnel barrier that has potential for efficient spin polarized tunneling from ferromagnets. Here, we demonstrate the spin filtering effect in cobalt|few layer h-BN|graphene junctions leading to a large negative spin polarization in graphene at room temperature. Through nonlocal pure spin transport and Hanle precession measurements performed on devices with different interface barrier conditions, we associate the negative spin polarization with high resistance few layer h-BN|ferromagnet contacts. Detailed bias and gate dependent measurements reinforce the robustness of the effect in our devices. These spintronic effects in two-dimensional van der Waals heterostructures hold promise for future spin based logic and memory applications. PMID:26883717

  9. Inversion of Spin Signal and Spin Filtering in Ferromagnet|Hexagonal Boron Nitride-Graphene van der Waals Heterostructures

    NASA Astrophysics Data System (ADS)

    Kamalakar, M. Venkata; Dankert, André; Kelly, Paul J.; Dash, Saroj P.

    2016-02-01

    Two dimensional atomically thin crystals of graphene and its insulating isomorph hexagonal boron nitride (h-BN) are promising materials for spintronic applications. While graphene is an ideal medium for long distance spin transport, h-BN is an insulating tunnel barrier that has potential for efficient spin polarized tunneling from ferromagnets. Here, we demonstrate the spin filtering effect in cobalt|few layer h-BN|graphene junctions leading to a large negative spin polarization in graphene at room temperature. Through nonlocal pure spin transport and Hanle precession measurements performed on devices with different interface barrier conditions, we associate the negative spin polarization with high resistance few layer h-BN|ferromagnet contacts. Detailed bias and gate dependent measurements reinforce the robustness of the effect in our devices. These spintronic effects in two-dimensional van der Waals heterostructures hold promise for future spin based logic and memory applications.

  10. Hexapole magnet system for thermal energy 3He atom manipulation

    NASA Astrophysics Data System (ADS)

    Jardine, A. P.; Fouquet, P.; Ellis, J.; Allison, W.

    2001-10-01

    We present design and construction details for a novel high field, small bore permanent hexapole magnet. The design is intended for focusing atomic beams of 3He at thermal energies. The magnet uses an optimized polepiece design which includes vacuum gaps to enable its use with high intensity atomic and molecular beams. The 0.3 m long, 1 mm internal radius magnet achieves a polepiece tip field of 1.1 T using NdFeB permanent magnets and Permendur 49 polepieces. The polepiece shanks are designed to saturate so that the hexapole properties are determined predominantly by the shape of the polepiece tip. The performance of the hexapole assembly is demonstrated with an 8 meV 3He beam in the beam source of the Cambridge spin echo spectrometer and the measured focused beam results show excellent agreement with theoretical predictions and negligible beam attenuation.

  11. Zircon 4He/3He thermochronometry

    NASA Astrophysics Data System (ADS)

    Tripathy-Lang, Alka; Fox, Matthew; Shuster, David L.

    2015-10-01

    Multiple thermochronometric methods are often required to constrain time-continuous rock exhumation for studying tectonic processes or development of km-scale topography at Earth's surface. Here, we explore 4He/3He thermochronometry of zircon as a method for constraining continuous time-temperature (t-T) paths of individual samples through a temperature range that is complementary to methods such as 40Ar/39Ar thermochronometry of K-feldspar and 4He/3He thermochronometry of apatite. For different cooling rates and diffusion domain size, the temperature sensitivity of zircon 4He/3He thermochronometry ranges from slightly less than 100 °C to slightly greater than 250 °C; a typical sample provides continuous thermal constraints over ∼100 °C within that range. Outside these temperatures, 4He in zircon will either be quantitatively retained or completely lost by volume diffusion. As proof-of-concept, we present stepwise release 4He/3He spectra and associated U and Th concentration maps measured by laser ablation ICP-MS analysis of individual crystal aliquots of Fish Canyon Tuff (FCT) zircon and of a more complex setting in the Sierra Nevada batholith that experienced reheating from a proximal basaltic intrusion, the Little Devil's Postpile (LDP). The FCT zircon 4He/3He release spectra are consistent with a 4He spatial distribution dominated by alpha-ejection from crystal surfaces. The spatial distributions of U and Th measured in the same crystals do not substantially influence 4He/3He release spectra that are predicted for the known thermal history, even when incorporating spatially variable diffusivity due to accumulation of radiation damage. Conversely, the LDP 4He/3He release spectra are strongly influenced by the observed parent nuclide zonation. A three-dimensional (3D) numerical model of 4He production and diffusion, which incorporates crystal geometry, U and Th zonation, and spatially variable He diffusion kinetics, substantially improves the fit between

  12. Polarization of3He and3He-4He mixtures with the castaing-nozieres method

    NASA Astrophysics Data System (ADS)

    van Woerkens, C. M. C. M.; Remeijer, P.; Steel, S. C.; Jochemsen, R.; Frossati, G.

    1996-01-01

    We describe experiments employing a strongly improved technique to prepare highly polarized3He and3He-4He mixtures. The polarization is obtained with the rapid melting method. A novel design cell using Vespel SP-1 (a sintered form of polyimide) can reach relative volume changes of 17%, which is required to decompress a completely solid3He-4He mixture to a completely liquid state at 23 bar.

  13. Single-Quantum Coherence Filter for Strongly Coupled Spin Systems for Localized 1H NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Trabesinger, Andreas H.; Mueller, D. Christoph; Boesiger, Peter

    2000-08-01

    A pulse sequence for localized in vivo1H NMR spectroscopy is presented, which selectively filters single-quantum coherence built up by strongly coupled spin systems. Uncoupled and weakly coupled spin systems do not contribute to the signal output. Analytical calculations using a product operator description of the strongly coupled AB spin system as well as in vitro tests demonstrate that the proposed filter produces a signal output for a strongly coupled AB spin system, whereas the resonances of a weakly coupled AX spin system and of uncoupled spins are widely suppressed. As a potential application, the detection of the strongly coupled AA‧BB‧ spin system of taurine at 1.5 T is discussed.

  14. Coherent Photoproduction of pi^+ from 3/^He

    SciTech Connect

    Rakhsha Nasseripour, Barry Berman

    2011-03-01

    We have measured the differential cross section for the $\\gamma$$^3$He$\\rightarrow \\pi^+ t$ reaction. This reaction was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid $^3$He target. The differential cross sections for the $\\gamma$$^3$He$\\rightarrow \\pi^+ t$ reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model.

  15. Photoproduction of eta-mesic 3He.

    PubMed

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

    2004-06-25

    The photoproduction of eta-mesic 3He has been investigated using the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI. The total inclusive cross section for the reaction gamma3He-->etaX has been measured for photon energies from threshold to 820 MeV. The total and angular differential coherent eta cross sections have been extracted up to energies of 745 MeV. A resonancelike structure just above the eta production threshold with an isotropic angular distribution suggests the existence of a resonant quasibound state. This is supported by studies of a competing decay channel of such a quasibound eta-mesic nucleus into pi(0)pX. A binding energy of (-4.4+/-4.2) MeV and a width of (25.6+/-6.1) MeV is deduced for the quasibound eta-mesic state in 3He. PMID:15244998

  16. Hyperfine structure of /sup 3/He

    SciTech Connect

    Druzbick, J.; Williams, H.T.

    1987-01-01

    Relativistic contribution to the hyperfine structure of /sup 3/He are reexamined in order to resolve inconsistencies in published values. The orbit-orbit and diamagnetic screening contributions are recomputed and are found to contribute less than one part per million (ppm), contrary to previous results. A new value (318 ppm compared to the perturbation result of 327 ppm) is obtained for the relativistic velocity correction using recently available relativistic Hartree-Fock wave functions. New values of the hyperfine-structure splitting of /sup 3/He in the 1S2S state and the /sup 3/He ion in the 1S and 2S states are presented. Comparison with experiment suggests that the relativistic velocity correction should be 323 ppm and the nuclear structure correction should be 184.2 ppm.

  17. Nuclear electric dipole moment of 3He

    SciTech Connect

    Stetcu, Ionel; Friar, J L; Hayes, A C; Liu, C P; Navratil, P

    2008-01-01

    In the no-core shell model (NCSM) framework, we calculate the {sup 3}He electric dipole moment (EDM) generated by parity- and time-reversal violation in the nucleon-nucleon interaction. While the results are somehow sensitive to the interaction model chosen for the strong two- and three-body interactions, we demonstrate the pion-exchange dominance to the EDM of {sup 3}He, if the coupling constants for {pi}, {rho} and {omega}-exchanges are of comparable magnitude, as expected. Finally, our results suggest that a measurement of {sup 3}He EDM would be complementary to the currently planned neutron and deuteron experiments, and would constitute a powerful constraint to the models of the pion P- and T-violating interactions.

  18. A valley and spin filter based on gapped graphene

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Long, Mengqiu; Zhao, Wen-Sheng; Hu, Yue; Wang, Gaofeng; Chan, K. S.

    2016-07-01

    We study highly valley- and spin-polarized current in single-layer gapped graphene without spin–orbit coupling. The structure considered is a three-barrier structure with one spin-splitting barrier and two electrical potential barriers with vector potentials. The electrons in the two valleys transmit differently because of the valley-dependent reflection between two adjacent barriers, while the spin-up and spin-down electrons transmit differently because of the spin splitting. The structure is different from other structures in which spin–orbit coupling plays an important role in the observation of valley- and spin-polarized current. We can control the spin and valley polarization by changing the width of the barrier or the strength of the spin splitting. The structure proposed in this paper can be used to make valley and spin devices.

  19. Nearly Perfect Spin Filter, Spin Valve and Negative Differential Resistance Effects in a Fe4-based Single-molecule Junction

    NASA Astrophysics Data System (ADS)

    Zu, Fengxia; Liu, Zuli; Yao, Kailun; Gao, Guoying; Fu, Huahua; Zhu, Sicong; Ni, Yun; Peng, Li

    2014-05-01

    The spin-polarized transport in a single-molecule magnet Fe4 sandwiched between two gold electrodes is studied, using nonequilibrium Green's functions in combination with the density-functional theory. We predict that the device possesses spin filter effect (SFE), spin valve effect (SVE), and negative differential resistance (NDR) behavior. Moreover, we also find that the appropriate chemical ligand, coupling the single molecule to leads, is a key factor for manipulating spin-dependent transport. The device containing the methyl ligand behaves as a nearly perfect spin filter with efficiency approaching 100%, and the transport is dominated by transmission through the Fe4 metal center. However, in the case of phenyl ligand, the spin filter effect seems to be reduced, but the spin valve effect is significantly enhanced with a large magnetoresistance ratio, reaching 1800%. This may be attributed to the blocking effect of the phenyl ligands in mediating transport. Our findings suggest that such a multifunctional molecular device, possessing SVE, NDR and high SFE simultaneously, would be an excellent candidate for spintronics of molecular devices.

  20. Nearly Perfect Spin Filter, Spin Valve and Negative Differential Resistance Effects in a Fe4-based Single-molecule Junction

    PubMed Central

    Zu, Fengxia; Liu, Zuli; Yao, Kailun; Gao, Guoying; Fu, Huahua; Zhu, Sicong; Ni, Yun; Peng, Li

    2014-01-01

    The spin-polarized transport in a single-molecule magnet Fe4 sandwiched between two gold electrodes is studied, using nonequilibrium Green's functions in combination with the density-functional theory. We predict that the device possesses spin filter effect (SFE), spin valve effect (SVE), and negative differential resistance (NDR) behavior. Moreover, we also find that the appropriate chemical ligand, coupling the single molecule to leads, is a key factor for manipulating spin-dependent transport. The device containing the methyl ligand behaves as a nearly perfect spin filter with efficiency approaching 100%, and the transport is dominated by transmission through the Fe4 metal center. However, in the case of phenyl ligand, the spin filter effect seems to be reduced, but the spin valve effect is significantly enhanced with a large magnetoresistance ratio, reaching 1800%. This may be attributed to the blocking effect of the phenyl ligands in mediating transport. Our findings suggest that such a multifunctional molecular device, possessing SVE, NDR and high SFE simultaneously, would be an excellent candidate for spintronics of molecular devices. PMID:24787446

  1. Search for Spin Filtering By Electron Tunneling Through Ferromagnetic EuS Barriers in Pbs

    NASA Technical Reports Server (NTRS)

    Figielski, T.; Morawski, A.; Wosinski, T.; Wrotek, S.; Makosa, A.; Lusakowska, E.; Story, T.; Sipatov, A. Yu.; Szczerbakow, A.; Grasza, K.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Perpendicular transport through single- and double-barrier heterostructures consisting of ferromagnetic EuS layers embedded into PbS matrix was investigated. Manifestations of both resonant tunneling and spin filtering through EuS barrier have been observed.

  2. Spin Filtering of Stored (Anti)Protons: from FILTEX to COSY to AD to FAIR

    SciTech Connect

    Nikolaev, Nikolai; Pavlov, Fyodor

    2008-04-30

    We review the theory of spin filtering of stored (anti) protons by multiple passage through a polarized internal target (PIT). The implications for the antiproton polarization buildup in the proposed PAX experiment at FAIR are discussed.

  3. Spin Filtering of Stored (Anti)Protons: from FILTEX to COSY to AD to FAIR

    SciTech Connect

    Nikolaev, Nikolai; Pavlov, Fyodor

    2007-06-13

    We review the theory of spin filtering of stored (anti)protons by multiple passage through the polarized internal target (PIT). Implications for the antiproton polarization buildup in the proposed PAX experiment at FAIR GSI are discussed.

  4. Spin-filter device based on the Rashba effect using a nonmagnetic resonant tunneling diode.

    PubMed

    Koga, Takaaki; Nitta, Junsaku; Takayanagi, Hideaki; Datta, Supriyo

    2002-03-25

    We propose an electronic spin-filter device that uses a nonmagnetic triple barrier resonant tunneling diode (TB-RTD). This device combines the spin-split resonant tunneling levels induced by the Rashba spin-orbit interaction and the spin blockade phenomena between two regions separated by the middle barrier in the TB-RTD. Detailed calculations using the InAlAs/InGaAs material system reveal that a splitting of a peak should be observed in the I-V curve of this device as a result of the spin-filtering effect. The filtering efficiency exceeds 99.9% at the peak positions in the I-V curve. PMID:11909487

  5. Toward polarized antiprotons: machine development for spin-filtering experiments at COSY

    NASA Astrophysics Data System (ADS)

    Weidemann, Christian; the PAX Collaboration

    2015-11-01

    In 2011 the Polarized Antiproton eXperiments Collaboration has performed a successful spin-filtering test using protons at {T}p=49.3 MeV at the COSY ring in Jülich, which allowed the determination of the spin-dependent polarizing cross section, that compares well with the theoretical prediction from the nucleon-nucleon potential and it confirms that spin filtering can be adopted as a method to polarize a stored beam. The document concentrates on the commissioning of the experimental equipment and the machine studies conducted to achieve the required beam lifetimes of τ =8000 s in the presence of a dense polarized hydrogen storage cell target of areal density {d}{{t}}=(5.5+/- 0.2)× {10}13 {atoms} {{cm}}-2. The developed techniques can be directly applied to antiproton machines and allow for the determination of the spin-dependent \\bar{p}p cross sections via spin filtering.

  6. Spin filtering neutrons with a proton target dynamically polarized using photo-excited triplet states

    NASA Astrophysics Data System (ADS)

    Haag, M.; van den Brandt, B.; Eichhorn, T. R.; Hautle, P.; Wenckebach, W. Th.

    2012-06-01

    In a test of principle a neutron spin filter has been built, which is based on dynamic nuclear polarization (DNP) using photo-excited triplet states. This DNP method has advantages over classical concepts as the requirements for cryogenic equipment and magnets are much relaxed: the spin filter is operated in a field of 0.3 T at a temperature of about 100 K and has performed reliably over periods of several weeks. The neutron beam was also used to analyze the polarization of the target employed as a spin filter. We obtained an independent measurement of the proton spin polarization of ˜0.13 in good agreement with the value determined with NMR. Moreover, the neutron beam was used to measure the proton spin polarization as a function of position in the naphthalene sample. The polarization was found to be homogeneous, even at low laser power, in contradiction to existing models describing the photo-excitation process.

  7. An Empirical Comparison between Two Recursive Filters for Attitude and Rate Estimation of Spinning Spacecraft

    NASA Technical Reports Server (NTRS)

    Harman, Richard R.

    2006-01-01

    The advantages of inducing a constant spin rate on a spacecraft are well known. A variety of science missions have used this technique as a relatively low cost method for conducting science. Starting in the late 1970s, NASA focused on building spacecraft using 3-axis control as opposed to the single-axis control mentioned above. Considerable effort was expended toward sensor and control system development, as well as the development of ground systems to independently process the data. As a result, spinning spacecraft development and their resulting ground system development stagnated. In the 1990s, shrinking budgets made spinning spacecraft an attractive option for science. The attitude requirements for recent spinning spacecraft are more stringent and the ground systems must be enhanced in order to provide the necessary attitude estimation accuracy. Since spinning spacecraft (SC) typically have no gyroscopes for measuring attitude rate, any new estimator would need to rely on the spacecraft dynamics equations. One estimation technique that utilized the SC dynamics and has been used successfully in 3-axis gyro-less spacecraft ground systems is the pseudo-linear Kalman filter algorithm. Consequently, a pseudo-linear Kalman filter has been developed which directly estimates the spacecraft attitude quaternion and rate for a spinning SC. Recently, a filter using Markley variables was developed specifically for spinning spacecraft. The pseudo-linear Kalman filter has the advantage of being easier to implement but estimates the quaternion which, due to the relatively high spinning rate, changes rapidly for a spinning spacecraft. The Markley variable filter is more complicated to implement but, being based on the SC angular momentum, estimates parameters which vary slowly. This paper presents a comparison of the performance of these two filters. Monte-Carlo simulation runs will be presented which demonstrate the advantages and disadvantages of both filters.

  8. Silicene-based spin-filter device: impact of random vacancies

    NASA Astrophysics Data System (ADS)

    Núñez, C.; Domínguez-Adame, F.; Orellana, P. A.; Rosales, L.; Römer, R. A.

    2016-06-01

    We propose a hybrid spin-filter device based on a silicene nanoribbon. A ferroelectric polymer grown on top of the nanoribbon splits spin-up and spin-down electron bands and gives rise to a spin polarisation of the conductance. In particular, we study the effects of a random distribution of vacancies on the performance of this spin-filter device. Disorder induces Anderson localisation of electrons and we find that the localisation length strongly depends on the electron spin. By adjusting the Fermi level of the source contact, only electrons with one spin orientation can reach the drain contact because their localisation length is larger than the length of the device. Electrons with opposite spin are largely back-reflected. Electric conductance then becomes spin polarised and the device behaves as a quasi-half-metal. We conclude that a moderate concentration of vacancies has little impact on the spin-filter capabilities of the device, opening the possibility to using it as a tuneable source of polarised electrons.

  9. Applications of {sup 3}He neutron detectors

    SciTech Connect

    Testov, D. A.; Briancon, Ch.; Dmitriev, S. N.; Yeremin, A. V.; Penionzhkevich, Yu. E.; Pyatkov, Yu. V.; Sokol, E. A.

    2009-01-15

    Neutron detectors with {sup 3}He-filled proportional counters are described. The use of these detectors in measuring the probability of neutron emission (in particular, multiparticle neutron emission) after the {beta} decay of neutron-rich nuclei and in studying rare events of spontaneous fission of superheavy nuclei is considered.

  10. Protecting nickel with graphene spin-filtering membranes: A single layer is enough

    SciTech Connect

    Martin, M.-B.; Dlubak, B.; Piquemal-Banci, M.; Collin, S.; Petroff, F.; Anane, A.; Fert, A.; Seneor, P.; Yang, H.; Blume, R.; Schloegl, R.

    2015-07-06

    We report on the demonstration of ferromagnetic spin injectors for spintronics which are protected against oxidation through passivation by a single layer of graphene. The graphene monolayer is directly grown by catalytic chemical vapor deposition on pre-patterned nickel electrodes. X-ray photoelectron spectroscopy reveals that even with its monoatomic thickness, monolayer graphene still efficiently protects spin sources against oxidation in ambient air. The resulting single layer passivated electrodes are integrated into spin valves and demonstrated to act as spin polarizers. Strikingly, the atom-thick graphene layer is shown to be sufficient to induce a characteristic spin filtering effect evidenced through the sign reversal of the measured magnetoresistance.

  11. Noise Studies of Polarimetry Systems for Polarized 3 He Targets

    NASA Astrophysics Data System (ADS)

    Katugampola, Sumudu K.; Matyas, Daniel J.; Nelyubin, Vladimir; Wang, Yunxiao; Cates, Gordon D.

    2015-04-01

    The NMR technique of adiabatic fast passage (AFP) plays an important role in 3 He targets polarized using spin-exchange optical pumping. Since AFP signals before amplification are generally small, identifying these signals amidst noise caused by external electromagnetic interference and micro-phonics can be challenging. When using thermally polarized water samples for absolute calibration of AFP signals, electromagnetic and micro-phonic noise can easily dominate. Although both types of interference have often been cited as the predominant sources of noise during AFP, few studies of these effects have been done under the conditions that are typical for a polarized 3 He target. This talk will describe studies of electromagnetic and micro-phonic noise using a small-scale prototype NMR system similar to those we use to study polarized 3 He targets. We will describe the effect of using aluminum metal shielding and other methods to minimize noise. We are using these studies to inform the design of a full-scale set up that will be used to test next-generation targets for use at Jefferson Lab, and measure atomic parameters relevant to polarimetry.

  12. Open quantum billiard in a magnetic field: A perfect spin filter

    SciTech Connect

    Isupova, G. G. Malyshev, A. I.

    2015-10-15

    The transport properties of an open system, a circular billiard with attached channels, are studied in the presence of Rashba spin-orbit coupling. The inclusion of even a weak magnetic field in the structure plane is shown to cause the conductance to become dependent on the spin state of charge carriers. By choosing the system’s parameters, this property allows a spin filter based on it to be realized.

  13. A spin-filter made of quantum anomalous Hall insulator nanowires

    SciTech Connect

    Wu, Jiansheng

    2014-07-28

    Topological end states (TES) in quantum anomalous Hall insulator nanowires can induce tunneling within the gap. Such TES are spin polarized, thus the induced current is spin polarized as well, which can be used to construct a spin-filter applied in spintronics. An interferometry device is designed to control the polarized current as well. The advantage and finite size effect on this system are discussed.

  14. Studies of 3He polarization losses during NMR and EPR measurment and Polarized 3He target cell lifetime

    NASA Astrophysics Data System (ADS)

    An, Peibo

    2014-09-01

    The 3He target cell polarized by spin-exchange optical pumping(SEOP) is used as a neutron substitute to study the inner structure of the neutron. In our lab, nuclear-magnetic-resonance(NMR) is used to measure the relative polarization and electron-paramagnetic-resonance(EPR) is used to measure the spin exchange EPR frequency shift parameter of potassium and rubidium in our target cell presented in magnetic fields. The alkali in the cell is used to facilitate the polarization of 3He. The first part of my work presents the study of the polarization losses of the cell during both NMR and EPR. With the help of improved RF coils, we keep the background noise received by pickup coils reasonably low, but three other kinds of losses are inevitable: losses during Adiabatic Fast Passage (AFP) sweep, losses due to flux change caused by different cell orientation with respect to RF fields and physical losses. Fortunately there is only flux change in NMR measurements. The second part of my work presents the study of cell lifetime improvement. The polarization decreases in a process called relaxation exponentially. The lifetime of a cell is how long it can keep its polarization. The typical lifetime of cells produced in our lab is about 22 hours. With a newly designed vacuum system. The 3He target cell polarized by spin-exchange optical pumping(SEOP) is used as a neutron substitute to study the inner structure of the neutron. In our lab, nuclear-magnetic-resonance(NMR) is used to measure the relative polarization and electron-paramagnetic-resonance(EPR) is used to measure the spin exchange EPR frequency shift parameter of potassium and rubidium in our target cell presented in magnetic fields. The alkali in the cell is used to facilitate the polarization of 3He. The first part of my work presents the study of the polarization losses of the cell during both NMR and EPR. With the help of improved RF coils, we keep the background noise received by pickup coils reasonably low, but

  15. Rashba-Zeeman-effect-induced spin filtering energy windows in a quantum wire

    SciTech Connect

    Xiao, Xianbo Nie, Wenjie; Chen, Zhaoxia; Zhou, Guanghui; Li, Fei

    2014-06-14

    We perform a numerical study on the spin-resolved transport in a quantum wire (QW) under the modulation of both Rashba spin-orbit coupling (SOC) and a perpendicular magnetic field by using the developed Usuki transfer-matrix method in combination with the Landauer-Büttiker formalism. Wide spin filtering energy windows can be achieved in this system for unpolarized spin injection. In addition, both the width of energy window and the magnitude of spin conductance within these energy windows can be tuned by varying Rashba SOC strength, which can be apprehended by analyzing the energy dispersions and spin-polarized density distributions inside the QW, respectively. Further study also demonstrates that these Rashba-SOC-controlled spin filtering energy windows show a strong robustness against disorders. These findings may not only benefit to further understand the spin-dependent transport properties of a QW in the presence of external fields but also provide a theoretical instruction to design a spin filter device.

  16. Multiple quantum filtering and spin exchange in solid state nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Ba, Yong; Ripmeester, John A.

    1998-05-01

    Multiple quantum NMR of coupled spin-1/2 nuclei in a solid has been exploited as a filter to separate different magnetization components in a spatially heterogeneous system. After filtering, the spins labeled according to coherence orders were used to follow the track of spin exchange between different domains. In order to avoid time-consuming two-dimensional experiments, this exchange was detected in a one-dimensional experiment via selective detection of multiple quantum coherences. The technique was demonstrated for samples of solid adamantane in contact with its saturated solution in benzene-d6 and for a high-density polyoxymethylene.

  17. Interfacial spin-filter assisted spin transfer torque effect in Co/BeO/Co magnetic tunnel junction

    SciTech Connect

    Tang, Y.-H. Chu, F.-C.

    2015-03-07

    The first-principles calculation is employed to demonstrate the spin-selective transport properties and the non-collinear spin-transfer torque (STT) effect in the newly proposed Co/BeO/Co magnetic tunnel junction. The subtle spin-polarized charge transfer solely at O/Co interface gives rise to the interfacial spin-filter (ISF) effect, which can be simulated within the tight binding model to verify the general expression of STT. This allows us to predict the asymmetric bias behavior of non-collinear STT directly via the interplay between the first-principles calculated spin current densities in collinear magnetic configurations. We believe that the ISF effect, introduced by the combination between wurtzite-BeO barrier and the fcc-Co electrode, may open a new and promising route in semiconductor-based spintronics applications.

  18. Surface tension maximum of liquid 3He

    NASA Astrophysics Data System (ADS)

    Matsumoto, Koichi; Hasegawa, Syuichi; Suzuki, Masaru; Okuda, Yuichi

    2000-07-01

    The surface tension of liquid 3He was measured using the capillary-rise method. Suzuki et al. have reported that its temperature dependence was almost quenched below 120 mK. Here we have examined it with higher precision and found that it has a small maximum around 100 mK. The amount of the maximum is about 3×10 -4 as a fraction of the surface tension at 0 K. The density of liquid 3He increases with temperature by about 5×10 -4 in Δ ρ/ ρ between 0 and 100 mK. This density change could be one of the reasons of the surface tension maximum around 100 mK.

  19. Nematic versus ferromagnetic spin filtering of triplet Cooper pairs in superconducting spintronics

    NASA Astrophysics Data System (ADS)

    Moor, Andreas; Volkov, Anatoly F.; Efetov, Konstantin B.

    2015-11-01

    We consider two types of magnetic Josephson junctions (JJ). They are formed by two singlet superconductors S and magnetic layers between them so that the JJ is a heterostructure of the Sm/n /Sm type, where Sm includes two magnetic layers with noncollinear magnetization vectors. One layer is represented by a weak ferromagnet and another one—the spin filter—is either conducting strong ferromagnet (nematic or N -type JJ) or magnetic tunnel barrier with spin-dependent transparency (magnetic or M -type JJ). Due to spin filtering only a fully polarized triplet component penetrates the normal n wire and provides the Josephson coupling between the superconductors S. Although both filters let to pass triplet Cooper pairs with total spin S parallel to the filter axes, the behavior of nematic and magnetic JJs is completely different. Whereas in the nematic case the charge and spin currents, IQ and Isp, do not depend on mutual orientation of the filter axes, both currents vanish in magnetic JJ in the case of antiparallel filter axes, and change sign with reversal of the filter direction. The obtained expressions for IQ and Isp clearly show a duality between the superconducting phase φ and the angle α between the exchange fields in the weak magnetic layers.

  20. The spectra of mixed 3He-4He droplets.

    PubMed

    Fantoni, S; Guardiola, R; Navarro, J; Zuker, A

    2005-08-01

    The diffusion Monte Carlo technique is used to calculate and analyze the excitation spectrum of 3He atoms bound to a cluster of 4He atoms by using a previously determined optimum filling of single-fermion orbits with well-defined orbital angular momentum L, spin S, and parity quantum numbers. The study concentrates on the energies and shapes of the three kinds of states for which the fermionic part of the wave function is a single Slater determinant: maximum L or maximum S states within a given orbit, and fully polarized clusters. The picture that emerges is that of systems with strong shell effects, whose binding and excitation energies are essentially determined by averages over configuration at fixed number of particles and spin, i.e., by the monopole properties of an effective Hamiltonian. PMID:16108665

  1. Investigation of the {sup 3}He wave function by quasifree scattering

    SciTech Connect

    Jones, C.E.; Hansen, J.O.; Bloch, C.

    1995-08-01

    The analysis of the data from the CE25 experiment at IUCF, which measured the target and beam analyzing powers and the spin correlation parameter in {sup 3}He(p,2p) and {sup 3}He(p,pn) quasielastic scattering, is nearing completion. At low missing momentum, the extracted polarization of the neutron and proton in {sup 3}He are consistent with Faddeev calculations. Two papers, one reporting the physics results and one describing the experiment, were published. The data from this experiment indicates that for q {>=} 500 MeV/c the plane wave impulse approximation is valid.

  2. Model formalism of liquid /sup 3/He-B at equilibrium

    SciTech Connect

    Goldstein, L.; Goldstein, J.C.

    1980-04-01

    The approximate formal treatment of the nuclear spin system of normal liquid /sup 3/He given some time ago is extended to the ordered /sup 3/He phase. The formalism leads to the prediction of normal thermal behavior of /sup 3/He-B at lower pressures and at temperatures approaching its phase-boundary temperatures. In contrast to the disordered normal liquid phase, which is thermally anomalous, the entropy of the /sup 3/He-B decreases on isothermal compression, or its isobaric volume expansion coefficient is positive. The equilibrium thermal behavior of ordered /sup 3/He-B is thus qualitatively different from that of disordered liquid /sup 3/He. Experimental control of these aspects of the liquid /sup 3/He phase transformation is lacking at the present time. Both early and new /sup 3/He-B paramagnetic susceptibility data, extended recently over a wide reduced-temperature range, disclose a fundamental competition between the spontaneous ordering mechanism responsible for the existence of /sup 3/He-B and the specific ordering process imposed upon this phase on application of an external constant and uniform magnetic field. As a consequence, magnetized /sup 3/He-B will be shown to increase its entropy on isothermal magnetization and to cool on adiabatic magnetization. The magnetocaloric effect is, however, only moderate. The competition of the ordering process leads to the delay or possibly even to the suppression of the formation of the ordered phase, a state of affairs foreseen in our earlier work. At low or moderate magnetic field strengths, the zero-field phase-boundary temperatures are shown to shift toward lower temperatures while, simultaneously, the order of the phase change decreases, from second order, in the absence of the field, to first order. Although of model-theoretic character, involving limitations of various types, the rich physical content of /sup 3/He-B at equilibrium clearly emerges in the present work.

  3. Quantum filter of spin polarized states: Metal–dielectric–ferromagnetic/semiconductor device

    SciTech Connect

    Makarov, Vladimir I.; Khmelinskii, Igor

    2014-02-01

    Highlights: • Development of a new spintronics device. • Development of quantum spin polarized filters. • Development of theory of quantum spin polarized filter. - Abstract: Recently we proposed a model for the Quantum Spin-Polarized State Filter (QSPSF). The magnetic moments are transported selectively in this model, detached from the electric charge carriers. Thus, transfer of a spin-polarized state between two conductors was predicted in a system of two levels coupled by exchange interaction. The strength of the exchange interaction between the two conductive layers depends on the thickness of the dielectric layer separating them. External magnetic fields modulate spin-polarized state transfer, due to Zeeman level shift. Therefore, a linearly growing magnetic field generates a series of current peaks in a nearby coil. Thus, our spin-state filter should contain as least three nanolayers: (1) conductive or ferromagnetic; (2) dielectric; and (3) conductive or semiconductive. The spectrum of spin-polarized states generated by the filter device consists of a series of resonance peaks. In a simple case the number of lines equals S, the total spin angular momentum of discrete states in one of the coupled nanolayers. Presently we report spin-polarized state transport in metal–dielectric–ferromagnetic (MDF) and metal–dielectric–semiconductor (MDS) three-layer sandwich devices. The exchange-resonance spectra in such devices are quite specific, differing also from spectra observed earlier in other three-layer devices. The theoretical model is used to interpret the available experimental results. A detailed ab initio analysis of the magnetic-field dependence of the output magnetic moment averaged over the surface of the device was carried out. The model predicts the resonance structure of the signal, although at its present accuracy it cannot predict the positions of the spectral peaks.

  4. Investigation of domain size in polymer membranes using double quantum filtered spin diffusion MAS NMR.

    SciTech Connect

    Fujimoto, Cy H.; Alam, Todd Michael; Cherry, Brian Ray; Cornelius, Christopher James

    2005-02-01

    Solid-state {sup 1}H magic angle spinning (MAS) NMR was used to investigate sulfonated Diels-Alder poly(phenlylene) polymer membranes. Under high spinning speed {sup 1}H MAS conditions, the proton environments of the sulfonic acid and phenylene polymer backbone are resolved. A double-quantum (DQ) filter using the rotor-synchronized back-to-back (BABA) NMR multiple-pulse sequence allowed the selective suppression of the sulfonic proton environment in the {sup 1}H MAS NMR spectra. This DQ filter in conjunction with a spin diffusion NMR experiment was then used to measure the domain size of the sulfonic acid component within the membrane. In addition, the temperature dependence of the sulfonic acid spin-spin relaxation time (T{sub 2}) was determined, providing an estimate of the activation energy for the proton dynamics of the dehydrated membrane.

  5. Coupling between Solid 3He on Aerogel and Superfluid 3He in the Low Temperature Limit

    SciTech Connect

    Bradley, D. I.; Fisher, S. N.; Guenault, A. M.; Haley, R. P.; Pickett, G. R.; Tsepelin, V.; Whitehead, R. C. V.; Skyba, P.

    2006-09-07

    We have cooled liquid 3He contained in a 98% open aerogel sample surrounded by bulk superfluid 3He-B at zero pressure to below 120 {mu}K. The aerogel sample is placed in a quasiparticle blackbody radiator cooled by a Lancaster-style nuclear cooling stage to {approx}200 {mu}K. We monitor the temperature of the 3He inside the blackbody radiator using a vibrating wire resonator. We find that reducing the magnetic field on the aerogel sample causes substantial cooling of all the superfluid inside the blackbody radiator. We believe this is due to the demagnetization of the solid 3He layers on the aerogel strands. This system has potential for achieving extremely low temperatures in the confined fluid.

  6. Quantum Tunneling of ^3 He in Solid ^4 He: A New Analysis

    NASA Astrophysics Data System (ADS)

    Huan, C.; Kim, S. S.; Candela, D.; Sullivan, N. S.

    2016-06-01

    We discuss the analysis of the experimental values of the nuclear spin-lattice and spin-spin relaxation times for the tunneling of ^3 He as isotopic impurities in solid ^4 He. These two relaxation times cannot be described quantitatively using a unique correlation time although it is often presented as such in the literature. In this paper, we discuss how to distinguish the high-frequency portion of the spectral densities that determine the spin-lattice relaxation rates from the low-frequency components which determine the spin-spin relaxation rates.

  7. Spin filtering and switching action in a diamond network with magnetic-nonmagnetic atomic distribution.

    PubMed

    Pal, Biplab; Dutta, Paramita

    2016-01-01

    We propose a simple model quantum network consisting of diamond-shaped plaquettes with deterministic distribution of magnetic and non-magnetic atoms in presence of a uniform external magnetic flux in each plaquette and predict that such a simple model can be a prospective candidate for spin filter as well as flux driven spintronic switch. The orientations and the amplitudes of the substrate magnetic moments play a crucial role in the energy band engineering of the two spin channels which essentially gives us a control over the spin transmission leading to a spin filtering effect. The externally tunable magnetic flux plays an important role in inducing a switch on-switch off effect for both the spin states indicating the behavior like a spintronic switch. Even a correlated disorder configuration in the on-site potentials and in the magnetic moments may lead to disorder-induced spin filtering phenomenon where one of the spin channel gets entirely blocked leaving the other one transmitting over the entire allowed energy regime. All these features are established by evaluating the density of states and the two terminal transmission probabilities using the transfer-matrix formalism within a tight-binding framework. Experimental realization of our theoretical study may be helpful in designing new spintronic devices. PMID:27600958

  8. Spin filtering and switching action in a diamond network with magnetic-nonmagnetic atomic distribution

    PubMed Central

    Pal, Biplab; Dutta, Paramita

    2016-01-01

    We propose a simple model quantum network consisting of diamond-shaped plaquettes with deterministic distribution of magnetic and non-magnetic atoms in presence of a uniform external magnetic flux in each plaquette and predict that such a simple model can be a prospective candidate for spin filter as well as flux driven spintronic switch. The orientations and the amplitudes of the substrate magnetic moments play a crucial role in the energy band engineering of the two spin channels which essentially gives us a control over the spin transmission leading to a spin filtering effect. The externally tunable magnetic flux plays an important role in inducing a switch on-switch off effect for both the spin states indicating the behavior like a spintronic switch. Even a correlated disorder configuration in the on-site potentials and in the magnetic moments may lead to disorder-induced spin filtering phenomenon where one of the spin channel gets entirely blocked leaving the other one transmitting over the entire allowed energy regime. All these features are established by evaluating the density of states and the two terminal transmission probabilities using the transfer-matrix formalism within a tight-binding framework. Experimental realization of our theoretical study may be helpful in designing new spintronic devices. PMID:27600958

  9. Efficient spin filter and spin valve in a single-molecule magnet Fe{sub 4} between two graphene electrodes

    SciTech Connect

    Zu, Feng-Xia; Gao, Guo-Ying; Fu, Hua-Hua; Peng, Li; Yao, Kai-Lun; Xiong, Lun; Zhu, Si-Cong

    2015-12-21

    We propose a magnetic molecular junction consisting of a single-molecule magnet Fe{sub 4} connected two graphene electrodes and investigate transport properties, using the nonequilibrium Green's function method in combination with spin-polarized density-functional theory. The results show that the device can be used as a nearly perfect spin filter with efficiency approaching 100%. Our calculations provide crucial microscopic information how the four iron cores of the chemical structure are responsible for the spin-resolved transmissions. Moreover, it is also found that the device behaves as a highly efficient spin valve, which is an excellent candidate for spintronics of molecular devices. The idea of combining single-molecule magnets with graphene provides a direction in designing a new class of molecular spintronic devices.

  10. Efficient spin filter and spin valve in a single-molecule magnet Fe4 between two graphene electrodes

    NASA Astrophysics Data System (ADS)

    Zu, Feng-Xia; Gao, Guo-Ying; Fu, Hua-Hua; Xiong, Lun; Zhu, Si-Cong; Peng, Li; Yao, Kai-Lun

    2015-12-01

    We propose a magnetic molecular junction consisting of a single-molecule magnet Fe4 connected two graphene electrodes and investigate transport properties, using the nonequilibrium Green's function method in combination with spin-polarized density-functional theory. The results show that the device can be used as a nearly perfect spin filter with efficiency approaching 100%. Our calculations provide crucial microscopic information how the four iron cores of the chemical structure are responsible for the spin-resolved transmissions. Moreover, it is also found that the device behaves as a highly efficient spin valve, which is an excellent candidate for spintronics of molecular devices. The idea of combining single-molecule magnets with graphene provides a direction in designing a new class of molecular spintronic devices.

  11. Perfect spin filtering effect and negative differential behavior in phosphorus-doped zigzag graphene nanoribbons

    PubMed Central

    Zou, Fei; Zhu, Lin; Yao, Kailun

    2015-01-01

    On the basis of the density functional theory combined with the Keldysh nonequilibrium Green’s function method, we investigate the spin-dependent transport properties of single-edge phosphorus-doped ZGNR systems with different widths. The results show a perfect spin filtering effect reaching 100% at a wide bias range in both parallel (P) and antiparallel (AP) spin configurations for all systems, especially for 6-ZGNR-P system. Instructively, for the AP spin configuration, the spin down current of the 4-ZGNR-P system exhibits a negative differential effect. By analyzing the transmission spectrum and the spin-resolved band structures of the electrodes, we elucidate the mechanism for these peculiar properties. Our findings provide a new way to produce multifunctional spintronic devices based on phosphorus-doped zigzag graphene nanoribbons. PMID:26514646

  12. Nuclear Electric Dipole Moment of 3He

    SciTech Connect

    Stetcu, I; P.Liu, C; Friar, J L; Hayes, A C; Navratil, P

    2008-04-08

    A permanent electric dipole moment (EDM) of a physical system would require time-reversal (T) violation, which is equivalent to charge-conjugation-parity (CP) violation by CPT invariance. Experimental programs are currently pushing the limits on EDMs in atoms, nuclei, and the neutron to regimes of fundamental theoretical interest. Nuclear EDMs can be studied at ion storage rings with sensitivities that may be competitive with atomic and neutron measurements. Here we calculate the magnitude of the CP-violating EDM of {sup 3}He and the expected sensitivity of such a measurement to the underlying CP-violating interactions. Assuming that the coupling constants are of comparable magnitude for {pi}-, {rho}-, and {omega}-exchanges, we find that the pion-exchange contribution dominates. Finally, our results suggest that a measurement of the {sup 3}He EDM is complementary to the planned neutron and deuteron experiments, and could provide a powerful constraint for the theoretical models of the pion-nucleon P,T-violating interaction.

  13. Nuclear Electric Dipole Moment of ^{3}_He

    SciTech Connect

    Stetcu, I.; Liu, C.-P.; Friar, J. L.; Hayes, A. C.; Navratil, P.

    2008-01-01

    A permanent electric dipole moment (EDM) of a physical system would require time-reversal (T) violation, which is equivalent to charge-conjugation-parity (CP) violation by CPT invariance. Experimental programs are currently pushing the limits on EDMs in atoms, nuclei, and the neutron to regimes of fundamental theoretical interest. Nuclear EDMs can be studied at ion storage rings with sensitivities that may be competitive with atomic and neutron measurements. Here we calculate the magnitude of the CP-violating EDM of ^{3}_He and the expected sensitivity of such a measurement to the underlyng CP-violating interactions. Assuming that the coupling constants are of comparable magnitude for {\\pi}-, {\\rho}-, and {\\omega}-exchanges, we find that the pion-exchange contribution dominates. Our results suggest that a measurement of the ^{3}_He EDM is complementary to the planned neutron and deuteron experiments, and could provide a powerful constraint for the theoretical models of the pion-nucleon P,T-violating interaction.

  14. Nuclear Ordered Phases of Solid 3He in Silver Sinters

    NASA Astrophysics Data System (ADS)

    Schuberth, Erwin A.; Kath, Matthias; Bago, Simone

    2006-09-01

    To determine the exact spin structure of the nuclear magnetic ordered phases of solid 3He, the U2D2 low field and the high field phases above 0.4 T, a European Research and Training Network for neutron scattering from the ordered solid was established which consisted of a collaboration with the Hahn Meitner Institute, Berlin, and other European and US groups. For this experiment it is crucial to grow a single crystal within the sinter needed for cooling the solid to temperatures of the order of 500 μK and to keep it cold long enough to measure a magnetic neutron diffraction. The sinter is also necessary to absorb the major part (> 90%) of the heat generated by the neutron capture and decay reaction of the 3He nucleus. In this work we studied the growth of crystals in Ag sinters of different pore sizes and with different growth speeds to find an optimal way to obtain single crystalline samples, or at least samples with only a few grains. We used SQUID magnetometry and NMR to measure the magnetization in the ordered phases. They were indicated by the known drop of the intensity, both in the NMR signal and in the dc magnetization, for the U2D2 phase, and by an increase of about 30% for the high field phase. The best results for cooling were obtained with sinters made from 700 Å "Japanese powder" with a packing fraction of 50% which were annealed at 130 °C after sintering and then had a calculated particle size of about 4200 Å. In the dc magnetization we found a paramagnetic surface contribution from a few monolayers of 3He down to 500 μK in addition to the bulk magnetization.

  15. Effects of instrumental artifacts on triple quantum filtered NMR spectra for spin I = 3/2

    NASA Astrophysics Data System (ADS)

    Sun, Cheng; Wang, Xuefeng; Wang, Zhixiao

    2016-07-01

    In this work, the effects of various instrumental artifacts on the triple quantum filtered NMR spectra for spin I = 3/2 nuclei are investigated. The studied artifacts include finite pulse widths, phase errors, radio frequency field inhomogeneity and pulse transients, which are commonly encountered in practice. The triple quantum filtered spectra are numerically simulated, based on the evolution of the spin density operator under the Hamiltonian for the artifacts. The results show that the presence of the artifacts introduces a shape distortion in the spectrum as well as a variation in the peak intensity, compared with the spectrum without any artifacts. This work indicates that the existence of the instrumental artifacts may cause a misunderstanding of the triple quantum filtered NMR spectra in experiments. The results suggest that one be aware of the instrumental artifacts when performing the triple quantum filtered NMR experiments.

  16. Effects of instrumental artifacts on triple quantum filtered NMR spectra for spin I=3/2.

    PubMed

    Sun, Cheng; Wang, Xuefeng; Wang, Zhixiao

    2016-07-01

    In this work, the effects of various instrumental artifacts on the triple quantum filtered NMR spectra for spin I=3/2 nuclei are investigated. The studied artifacts include finite pulse widths, phase errors, radio frequency field inhomogeneity and pulse transients, which are commonly encountered in practice. The triple quantum filtered spectra are numerically simulated, based on the evolution of the spin density operator under the Hamiltonian for the artifacts. The results show that the presence of the artifacts introduces a shape distortion in the spectrum as well as a variation in the peak intensity, compared with the spectrum without any artifacts. This work indicates that the existence of the instrumental artifacts may cause a misunderstanding of the triple quantum filtered NMR spectra in experiments. The results suggest that one be aware of the instrumental artifacts when performing the triple quantum filtered NMR experiments. PMID:27149654

  17. Rhenium-phthalocyanine molecular nanojunction with high magnetic anisotropy and high spin filtering efficiency

    SciTech Connect

    Li, J.; Hu, J.; Wang, H.; Wu, R. Q.

    2015-07-20

    Using the density functional and non-equilibrium Green's function approaches, we studied the magnetic anisotropy and spin-filtering properties of various transition metal-Phthalocyanine molecular junctions across two Au electrodes. Our important finding is that the Au-RePc-Au junction has both large spin filtering efficiency (>80%) and large magnetic anisotropy energy, which makes it suitable for device applications. To provide insights for the further experimental work, we discussed the correlation between the transport property, magnetic anisotropy, and wave function features of the RePc molecule, and we also illustrated the possibility of controlling its magnetic state.

  18. The tunneling magnetic resistance in ferromagnetic junctions with spin-filter composite tunnel barriers

    NASA Astrophysics Data System (ADS)

    Xie, ZhengWei; Lv, Houxiang; Li, Ling; Xu, Ming

    2016-05-01

    Within the framework of the free-electron model, the tunneling magnetoresistance (TMR) in FM/I/SF/NM quasi-magnetic tunnel junctions (QMTJ) is investigated. FM, NM, I and SF represent the ferromagnetic metal, nonmagnetic metal, insulator and spin-filter barrier, respectively. Our results show that due to the spin-filtering effect in SF potential barriers, the FM/I/SF/NM can obtain relatively stabilized TMR in higher bias region when it has higher potential height and thicker SF barrier. And, for obtaining large TMR, the total thickness of the barrier region would be carefully selected as the influence of the supplementary I layer.

  19. A homonuclear spin-pair filter for solid-state NMR based on adiabatic-passage techniques

    NASA Astrophysics Data System (ADS)

    Verel, René; Baldus, Marc; Ernst, Matthias; Meier, Beat H.

    1998-05-01

    A filtering scheme for the selection of spin pairs (and larger spin clusters) under fast magic-angle spinning is proposed. The scheme exploits the avoided level crossing in spin pairs during an adiabatic amplitude sweep through the so-called HORROR recoupling condition. The advantages over presently used double-quantum filters are twofold. (i) The maximum theoretical filter efficiency is, due to the adiabatic variation, 100% instead of 73% as for transient methods. (ii) Since the filter does not rely on the phase-cycling properties of the double-quantum coherence, there is no need to obtain the full double-quantum intensity for all spins in the sample at one single point in time. The only important requirement is that all coupled spins pass through a two-spin state during the amplitude sweep. This makes the pulse scheme robust with respect to rf-amplitude missetting, rf-field inhomogeneity and chemical-shift offset.

  20. Effective theory of 3H and 3He

    NASA Astrophysics Data System (ADS)

    König, Sebastian; Grießhammer, Harald W.; Hammer, H.-W.; van Kolck, U.

    2016-06-01

    We present a new perturbative expansion for pionless effective field theory with Coulomb interactions in which at leading order (LO) the spin-singlet nucleon–nucleon channels are taken in the unitarity limit. Presenting results up to next-to-leading order for the Phillips line and the neutron–deuteron doublet-channel phase shift, we find that a perturbative expansion in the inverse {}1{S}0 scattering lengths converges rapidly. Using a new systematic treatment of the proton–proton sector that isolates the divergence due to one-photon exchange, we renormalize the corresponding contribution to the {}3{{H}} –{}3{He} binding energy splitting and demonstrate that the Coulomb force in pionless EFT is a completely perturbative effect in the trinucleon bound-state regime. In our new expansion, the LO is exactly isospin-symmetric. At next-to-leading order, we include isospin breaking via the Coulomb force and two-body scattering lengths, and find for the energy splitting {({E}B{(}3{He})-{E}B{(}3{{H}}))}{NLO}\\quad =(-0.86+/- 0.17)\\quad {MeV}.

  1. First observation of two hyperfine transitions in antiprotonic 3He

    PubMed Central

    Friedreich, S.; Barna, D.; Caspers, F.; Dax, A.; Hayano, R.S.; Hori, M.; Horváth, D.; Juhász, B.; Kobayashi, T.; Massiczek, O.; Sótér, A.; Todoroki, K.; Widmann, E.; Zmeskal, J.

    2011-01-01

    We report on the first experimental results for microwave spectroscopy of the hyperfine structure of p¯3He+. Due to the helium nuclear spin, p¯3He+ has a more complex hyperfine structure than p¯4He+, which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton. PMID:21822351

  2. Textural domain walls in superfluid 3He-B

    NASA Astrophysics Data System (ADS)

    Mizushima, Takeshi

    Owing to the richness of symmetry, the superfluid 3He serves as a rich repository of topological quantum phenomena. This includes the emergence of surface Majorana fermions and their quantum mass acquisition at the topological critical point. Furthermore, the marriage of the prototype topological superfluid with nanofabrication techniques brings about a rich variety of spontaneous symmetry breaking, such as the formation of the stripe order and nontrivial domain walls. In this work, we examine the possible formation of textural domain walls in the superfluid 3He-B confined to a thin slab with a sub-micron thickness. When an applied magnetic field is much higher than the dipolar field, two nearly degenerate ground states appear, which are characterized by the Ising order associated with the spontaneous breaking of a magnetic order-two symmetry, lcirc;z = + 1 and - 1 . We here discuss the structure of the textural domain wall formed by the spatial modulation of the Ising order, such as low-lying quasiparticle excitations and spontaneous spin current. We also report bosonic modes bound to the textural domain wall.

  3. Formation of 3He droplets in dilute 3He-4He solid solutions

    NASA Astrophysics Data System (ADS)

    Huan, Chao; Candela, Don; Kim, Sung; Yin, Liang; Xia, Jiang-Sheng; Sullivan, Neil

    2015-03-01

    We review the different stages of the formation of 3He droplets in dilute solid 3He-4He solutions. The studies are interesting because the phase separation in isotopic helium mixtures is a first-order transition with a conserved order parameter. The rate of growth of the droplets as observed in NMR studies is compared with the rates expected for homogeneous nucleation followed by a period of coarsening known as Ostwald ripening. Work suported by the National Science Foundation - DMR-1303599 and DMR- 1157490 (National High Magnetic Field Laboratory).

  4. {sup 3}He polarization via optical pumping in a birefringent cell

    SciTech Connect

    Masuda, Y.; Ino, T.; Skoy, V.R.; Jones, G.L.

    2005-08-01

    A sapphire cell was used to obtain a high {sup 3}He nuclear polarization by means of spin-exchange optical pumping. The phase-shift difference between ordinary and extraordinary rays is well controlled using the thickness of the birefringent sapphire window so that a high circular polarization is obtained in the cell. Neutron transmission through the polarized {sup 3}He gas was measured as a function of neutron energy. A large {sup 3}He polarization of 63{+-}1% was obtained at a {sup 3}He pressure of 3.1 atm. Neutron polarizations of 97 and 90 % were obtained with transmission rates of 15 and 22 % at 10 and 20 meV, respectively.

  5. {sup 3}He melting pressure thermometry

    SciTech Connect

    Ni, W.; Xia, J.S.; Adams, E.D.

    1995-10-01

    High-precision measurements of the {sup 3}He melting pressure versus temperature have been made from 500 {mu}K to 25 mK using a {sup 60}Co nuclear orientation primary thermometer and a Pt NMR susceptibility secondary thermometer. Temperatures for the fixed points on the melting curve are: the superfluid A transition T{sub A}=2.505 mK, the A-B transition T{sub AB}=1.948 mK, and the solid ordering temperature T{sub N}=0.934 mK. These fixed points and a functional form for P(T) constitute a convenient temperature scale, based on a primary thermometer, usable to well below 1 mK.

  6. Polarimetries for the Polarized 3 He Target at JLab

    NASA Astrophysics Data System (ADS)

    Ton, Nguyen; Jefferson Lab Polarized 3 He Target Collaboration

    2015-04-01

    At Jefferson Lab, a Polarized 3 He Target has been used as an effective polarized neutron target for studying nucleon spin structure. For the 12 GeV program at JLab, the first stage upgrade of the target aim to increase luminosity by a factor of 2 (to luminosity ~ 2 ×1036 cm-2s-1) while keep maximum in-beam polarization at 60 % with 30 μA beam current and reach a systematic uncertainty of polarimetry below 3 %. During the 6 GeV era, the target polarization was measured by two polarimetries: adiabatic fast passage-nuclear magnetic resonance (AFP-NMR) and electron paramagnetic resonance (EPR). With the upgrade, a new polarimetry, Pulse-NMR, is being studied in the lab for the up-coming metal coated target. In this talk, we will discuss the detail study of AFP-NMR, EPR, Pulsed-NMR measurements and their corresponding uncertainties.

  7. Electrodisintegration of 3He below and above deuteron breakup threshold

    SciTech Connect

    Marcucci, L. E.; Viviani, M.; Schiavilla, R.; Kievsky, A.; Rosati, S.

    2005-02-01

    Recent advances in the study of electrodisintegration of 3He are presented and discussed. The pair-correlated hyperspherical harmonics method is used to calculate the initial and final state wave functions, with a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana IX three-nucleon interactions. The model for the nuclear current and charge operators retains one- and many-body contributions. Particular attention is made in the construction of the two-body current operators arising from the momentum-dependent part of the two-nucleon interaction. Three-body current operators are also included so that the full current operator is strictly conserved. The present model for the nuclear current operator is tested comparing theoretical predictions and experimental data of pd radiative capture cross section and spin observables.

  8. Gate-tunable valley-spin filtering in silicene with magnetic barrier

    SciTech Connect

    Wu, X. Q.; Meng, H.

    2015-05-28

    We theoretically study the valley- and spin-resolved scattering through magnetic barrier in a one layer thick silicene, using the mode-matching method for the Dirac equation. We show that the spin-valley filtering effect can be achieved and can also be tuned completely through both a top and bottom gate. Moreover, when reversing the sign of the staggered potential, we find the direction of the valley polarization is switched while the direction of spin polarization is unchanged. These results can provide some meaningful information to design valley valve residing on silicene.

  9. Development of high-performance alkali-hybrid polarized 3He targets for electron scattering

    NASA Astrophysics Data System (ADS)

    Singh, Jaideep T.; Dolph, P. A. M.; Tobias, W. A.; Averett, T. D.; Kelleher, A.; Mooney, K. E.; Nelyubin, V. V.; Wang, Yunxiao; Zheng, Yuan; Cates, G. D.

    2015-05-01

    Background: Polarized 3He targets have been used as effective polarized neutron targets for electron scattering experiments for over twenty years. Over the last ten years, the effective luminosity of polarized 3He targets based on spin-exchange optical pumping has increased by over an order of magnitude. This has come about because of improvements in commercially-available lasers and an improved understanding of the physics behind the polarization process. Purpose: We present the development of high-performance polarized 3He targets for use in electron scattering experiments. Improvements in the performance of polarized 3He targets, target properties, and operating parameters are documented. Methods: We utilize the technique of alkali-hybrid spin-exchange optical pumping to polarize the 3He targets. Spectrally narrowed diode lasers used for the optical pumping greatly improved the performance. A simulation of the alkali-hybrid spin-exchange optical pumping process was developed to provide guidance in the design of the targets. Data was collected during the characterization of 24 separate glass target cells, each of which was constructed while preparing for one of four experiments at Jefferson Laboratory in Newport News, Virginia. Results: From the data obtained we made determinations of the so-called X -factors that quantify a temperature-dependent and as-yet poorly understood spin-relaxation mechanism that limits the maximum achievable 3He polarization to well under 100%. The presence of the X -factor spin-relaxation mechanism was clearly evident in our data. Good agreement between the simulation and the actual target performance was obtained by including details such as off-resonant optical pumping. Included in our results is a measurement of the K -3He spin-exchange rate coefficient kseK=(7.46 ±0.62 ) ×10-20cm3/s over the temperature range 503 K to 563 K. Conclusions: In order to achieve high performance under the operating conditions described in this paper

  10. Spin filtering in a δ-doped magnetic-electric-barrier nanostructure

    SciTech Connect

    Li, Shuai; Lu, Mao-Wang Jiang, Ya-Qing; Chen, Sai-Yan

    2014-09-15

    We report a theoretical study on spin-polarized transport in a δ-doped magnetic-electric-barrier nanostructure, which can be realized in experiments by depositing two ferromagnetic stripes on top and bottom of a semiconductor heterostructure under an applied voltage and by using atomic layer doping technique. The spin-polarized behavior of the electron in this device is found to be quite sensitive to the δ-doping. One can conveniently tune the degree of the electron spin polarization by adjusting the weight and/or position of the δ-doping. Thus, the involved nansosystem can be employed as a controllable spin filter, which may be helpful for exploiting new spin-polarized source for spintronics applications.

  11. Spin filtering in a δ-doped magnetic-electric-barrier nanostructure

    NASA Astrophysics Data System (ADS)

    Li, Shuai; Lu, Mao-Wang; Jiang, Ya-Qing; Chen, Sai-Yan

    2014-09-01

    We report a theoretical study on spin-polarized transport in a δ-doped magnetic-electric-barrier nanostructure, which can be realized in experiments by depositing two ferromagnetic stripes on top and bottom of a semiconductor heterostructure under an applied voltage and by using atomic layer doping technique. The spin-polarized behavior of the electron in this device is found to be quite sensitive to the δ-doping. One can conveniently tune the degree of the electron spin polarization by adjusting the weight and/or position of the δ-doping. Thus, the involved nansosystem can be employed as a controllable spin filter, which may be helpful for exploiting new spin-polarized source for spintronics applications.

  12. A dynamic model for power deposition in 3He lasers pumped by 3He(n,p) 3H reactions

    NASA Astrophysics Data System (ADS)

    Çetin, Füsun

    2004-07-01

    The coupled variation of power density with gas density in a nuclear-pumped laser, which is excited by 3He(n,p) 3H reaction products, is considered. In the literature, volumetric excitation by reaction products of 3He(n,p) 3H is only considered for the case in which gas density is uniform and does not change during the pumping. In this work, a time-dependent model describing the coupled fluid dynamic and particle transport behaviour of the gas has been developed. In modelling charge particle transport behaviour, a previously reported energy deposition model for a constant gas density is extended for a variable gas density by taking into account variations in the particle range, macroscopic cross sections and neutron flux depending on density field of the gas. The coupled equations, which are obtained by using the power deposition density expression obtained for variable gas density in the acoustically filtered equations of motion of the gas, are solved numerically. Spatial and temporal variations of power deposition density and gas density during the pumping pulse are determined for various operating pressures ranging from 0.5 to 10 atm. In the calculations, the characteristics of I.T.U TRIGA Mark-II Reactor are used and it is assumed that laser tube is placed in the centre of the reactor core. Obtained results are presented and examined.

  13. Effectiveness of organic molecules for spin filtering in an organic spin valve: Reaction-induced spin polarization for Co atop Alq 3

    NASA Astrophysics Data System (ADS)

    Lam, Tu-Ngoc; Lai, Yu-Ling; Chen, Chih-Han; Chen, Po-Hung; Chan, Yuet-Loy; Wei, Der-Hsin; Lin, Hong-Ji; Chen, C. T.; Wang, Jeng-Han; Sheu, Jeng-Tzong; Hsu, Yao-Jane

    2015-01-01

    The spin polarization of organic-ferromagnetic interfaces in an organic spin valve critically affects the efficiency of spin injection or detection. We examined the chemical and electronic properties of ferromagnetic Co deposited on organic Al q3 and the interfacial spin-polarized capability of the electronic states. Our x-ray photoemission spectra and calculations with density-functional theory indicate a sequential and unequal distribution of charge from Co clusters to N and then to O atoms in Al q3 . The preferential orbital hybridization at specific functional sites produces efficient spin polarization of organic molecules. Element-specific measurements of x-ray magnetic circular dichroism demonstrate the preferential spin polarization in the lowest unoccupied molecular orbital state of N atoms at the complex interface for Co atop Al q3 , which agrees satisfactorily with calculation. Our results indicate that an induced interfacial spin polarization on engineering the dominant reaction of Co with mainly N and O atoms in Al q3 might pave a way for effective spin filtering in organic spintronics.

  14. Double-Cell Geometry for 129Xe/3He Co-Magnetometry

    NASA Astrophysics Data System (ADS)

    Ohtomo, Yuichi; Ichikawa, Yuichi; Sato, Tomoya; Sakamoto, Yu; Kojima, Shuichiro; Suzuki, Takahiro; Shirai, Hazuki; Chikamori, Masatoshi; Hikota, Eri; Miyatake, Hirokazu; Nanao, Tsubasa; Suzuki, Kunifumi; Tsuchiya, Masato; Inoue, Takeshi; Furukawa, Takeshi; Yoshimi, Akihiro; Bidinosti, Christopher P.; Ino, Takashi; Ueno, Hideki; Matsuo, Yukari; Fukuyama, Takeshi; Asahi, Koichiro

    Comagnetometers play a key role in EDM experiments. They allow one to quantify, and subsequently correct for, any long-term drifts of the external magnetic field. In order to improve the performance of the 3He comagnetometer for our 129Xe EDM measurements, we have decided to incorporate a double-cell geometry which enables us to suppress a frequency shift due to contact interaction with polarized Rb atoms. In this study, the production and relaxation of 3He spin polarization in the double cell were studied. As a result, the followings were achieved: a polarization of 1.04(8)%, a longitudinal spin relaxation time of 10.1(5) h, and a transverse relaxation time of 2,340 s. With these improvements, concurrent operation of the 129Xe and 3He masers has been realized, and EDM measurement will be started in near future using a cell designed based on the results of this study.

  15. Silk screen based dual spin-filter module for perfusion culture of adherent and non-adherent mammalian cells.

    PubMed

    Kamthan, Shweta; Gomes, James; Roychoudhury, Pradip K

    2014-08-01

    Spin-filters have been primarily used for producing therapeutic proteins from mammalian cells. However, disposability and/or high filter clogging of the existing spin-filter systems affect the process economy and productivity. Hence, to address these drawbacks a reusable dual spin-filter module for perfusion culture of adherent and non-adherent mammalian cells was designed. Two non-woven Bombyx mori silk layers were used as filter screen; the outer layer was conducive to cell attachment whilst the inner was non-conducive. Adherent cells can be cultured either in suspended mode using its inner single module or as monolayer of cells using its dual concentric module. We achieved 30 % higher urokinase productivity as compared to the stainless-steel spin-filter during perfusion experiments of adherent human kidney cells in suspended mode. This was due to the hydrophobic and negatively-charged silk screen that allows clog-free perfusion culture for prolonged periods. PMID:24737079

  16. Spin polarized state filter based on semiconductor–dielectric–iron–semiconductor multi-nanolayer device

    SciTech Connect

    Makarov, Vladimir I.; Khmelinskii, Igor

    2015-04-15

    Highlights: • Development of a new spintronics device. • Development of quantum spin polarized filters. • Development of theory of quantum spin polarized filter. - Abstract: Presently we report spin-polarized state transport in semiconductor–dielectric–iron–semiconductor (SDIS) four-nanolayer sandwich devices. The exchange-resonance spectra in such devices are quite specific, differing also from spectra observed earlier in other three-nanolayer devices. The theoretical model developed earlier is extended and used to interpret the available experimental results. A detailed ab initio analysis of the magnetic-field dependence of the output magnetic moment is also performed. The model predicts an exchange spectrum comprising a series of peaks, with the spectral structure determined by several factors, discussed in the paper.

  17. Lunar source of /sup 3/He for commercial fusion power

    SciTech Connect

    Wittenberg, L.J.; Santarius, J.F.; Kulcinski, G.L.

    1986-09-01

    An analysis of astrophysical information indicates that the solar wind has deposited an abundant, easily extractable source of /sup 3/He onto the surface of the moon. Apollo lunar samples indicate that the moon's surface soil contains approx. =10/sup 9/kg of /sup 3/He. If this amount of /sup 3/He were to be used in a 50% efficient D-/sup 3/He fusion reactor, it would provide 10/sup 7/GW(electric) . yr of electrical power. The energy required to extract /sup 3/He from the lunar regolith and transport it to earth is calculated to be approx. =2400 GJ/kg. Since the D-/sup 3/He reaction produces 6 X 10/sup 5/ GJ of energy per kilogram of /sup 3/He, the energy payback ratio is approx. =250. Implications for the commercialization of D-/sup 3/He fusion reactors and for the development of fusion power are discussed.

  18. Entrance and exit channel phenomena in d- and 3He-induced preequilibrium decay

    NASA Astrophysics Data System (ADS)

    Bissem, H. H.; Georgi, R.; Scobel, W.; Ernst, J.; Kaba, M.; Rao, J. Rama; Strohe, H.

    1980-10-01

    Activation techniques were used to measure more than 30 excitation functions for single and multiple nucleon and/or α particle emission for d+64,66Zn, 89Y with Ed=9-26 MeV and 3He+63,65Cu, 93Nb with E(3He)=10-44 MeV. The excitation functions are generally in agreement with the results of a combined equilibrium and preequilibrium hybrid model calculation applying initial exciton numbers n0=3 for d and n0=4 for 3He reactions. The composite system 66Ga has been produced via d+64Zn and 3He+63Cu at excitation energies between 22 and 36 MeV. An entrance channel dependence shows up in the yields for single p- and n-emission when compared in the double ratio R=[σ(3He, p)σ(3He, n)][σ(d, p)σ(d, n)]. It approaches a value of about 2, indicating enhanced p emission for the 3He-induced reaction. This value disagrees with the equilibrium isospin formalism and is best reproduced by initial particle exciton numbers n0p=n0n=1.5 for d and n0p=2.5, n0n=1.5 for 3He projectiles, indicating conservation of charge asymmetry in the entrance channel. Isomeric ratios have been measured for 89Y(d, 2n)89Zr and 93Nb(3He, xn)96-xTc (x=1, 2, 3). Calculations with a full statistical model fail to reproduce σgσm as well as σg and σm for reasonable values of the spin cutoff parameter. Inclusion of a preequilibrium decay mode improves the fit, in particular if the angular momentum depletion of the composite system due to preequilibrium decay is increased over that of the equilibrium decay at the same channel energy. NUCLEAR REACTIONS 64,66Zn, 89Y(d, xnypzα), Ed=9-26 MeV, 63,65Cu, 93Nb(3He, xnypzα), E3He=10-44 MeV, x<=4, y<=1, z<=2 measured σ(E) by activation, enriched targets. Statistical model analysis including preequilibrium decay, deduced reaction mechanism, charge asymmetry conservation, spin depletion.

  19. Theoretical investigation of spin-filtering in CrAs/GaAs heterostructures

    SciTech Connect

    Stickler, B. A.; Ertler, C.; Pötz, W.; Chioncel, L.

    2013-12-14

    The electronic structure of bulk zinc-blende GaAs, zinc-blende and tetragonal CrAs, and CrAs/GaAs supercells, computed within linear muffin-tin orbital (LMTO) local spin-density functional theory, is used to extract the band alignment for the [1,0,0] GaAs/CrAs interface in dependence of the spin orientation. With the lateral lattice constant fixed to the experimental bulk GaAs value, a local energy minimum is found for a tetragonal CrAs unit cell with a longitudinal ([1,0,0]) lattice constant reduced by ≈2%. Due to the identified spin-dependent band alignment, half-metallicity of CrAs no longer is a key requirement for spin-filtering. Based on these findings, we study the spin-dependent tunneling current in [1,0,0] GaAs/CrAs/GaAs heterostructures within the non-equilibrium Green's function approach for an effective tight-binding Hamiltonian derived from the LMTO electronic structure. Results indicate that these heterostructures are promising candidates for efficient room-temperature all-semiconductor spin-filtering devices.

  20. 3He gas gap heat switch

    NASA Astrophysics Data System (ADS)

    Catarino, I.; Paine, C.

    2011-01-01

    Thermal control at 1 K is still demanding for heat switches development. A gas gap heat switch using 3He gas as the heat-transfer fluid was tested and characterized. The switch is actuated by a sorption pump, whose triggering temperatures were also characterized. Switching times were recorded for different thermalizations of the sorption pump. This paper presents the conductance results of such switch. The temperature scanning of the actuator is also presented. The effect of filling pressure is discussed as well as the thermalization of the sorption pump. About 60 μW/K OFF-state conductance and 100 mW/K ON-state conductance were obtained at 1.7 K. The actuation temperature is slightly adjustable upon the charging pressure of the working gas. Thermalization of the sorption pump at about 8-10 K is enough for producing an OFF state - it can be comfortably linked to a 4 K stage. Temperatures of 15-20 K at the sorption pump are required for reaching the viscous range for maximum ON conduction. Switching time dependence on the thermalization of the sorption pump is discarded.

  1. Quantum rings as a perfect spin-splitter and spin-filter by using the Rashba effect

    NASA Astrophysics Data System (ADS)

    Saeedi, Sevan; Faizabadi, Edris

    2016-05-01

    Spin related conductance and polarization via an open ballistic quantum nanoring connected to one input lead and two output ones are studied by considering the Rashba effect based on the transfer matrix method. Our probes show that controlling on Rashba strength leads to 100 percent spin polarization while we have high efficiency for the system. In addition, it is possible to design the position of input and output leads in such a way as to optimize the system to work as a spin filtering or spin switching nano device. Also, this apparatus can work as a Stern-Gerlach tool which can be used in some important practical nano-industrial applications. By controlling on Rashba strength in a special design of two output lead positions, it is possible to divide the input charge current into any output ones while the partial output charge current has substantial value in one of two output leads and it is reduced in the other one simultaneously. By controlling on Rashba strength in a special design of output lead positions, the spin conductance can attain a considerable value in one output lead despite an insignificant value in the other one simultaneously.

  2. Highly Efficient Room Temperature Spin Injection Using Spin Filtering in MgO

    NASA Astrophysics Data System (ADS)

    Jiang, Xin

    2007-03-01

    Efficient electrical spin injection into GaAs/AlGaAs quantum well structures was demonstrated using CoFe/MgO tunnel spin injectors at room temperature. The spin polarization of the injected electron current was inferred from the circular polarization of electroluminescence from the quantum well. Polarization values as high as 57% at 100 K and 47% at 290 K were obtained in a perpendicular magnetic field of 5 Tesla. The interface between the tunnel spin injector and the GaAs interface remained stable even after thermal annealing at 400 ^oC. The temperature dependence of the electron-hole recombination time and the electron spin relaxation time in the quantum well was measured using time-resolved optical techniques. By taking into account of these properties of the quantum well, the intrinsic spin injection efficiency can be deduced. We conclude that the efficiency of spin injection from a CoFe/MgO spin injector is nearly independent of temperature and, moreover, is highly efficient with an efficiency of ˜ 70% for the temperature range studied (10 K to room temperature). Tunnel spin injectors are thus highly promising components of future semiconductor spintronic devices. Collaborators: Roger Wang^1, 3, Gian Salis^2, Robert Shelby^1, Roger Macfarlane^1, Seth Bank^3, Glenn Solomon^3, James Harris^3, Stuart S. P. Parkin^1 ^1 IBM Almaden Research Center, San Jose, CA 95120 ^2 IBM Zurich Research Laboratory, S"aumerstrasse 4, 8803 R"uschlikon, Switzerland ^3 Solid States and Photonics Laboratory, Stanford University, Stanford, CA 94305

  3. Ferromagnetism and perfect spin filtering in transition-metal-doped graphyne nanoribbons

    NASA Astrophysics Data System (ADS)

    Pan, Jinbo; Du, Shixuan; Zhang, Yuyang; Pan, Lida; Zhang, Yanfang; Gao, Hong-Jun; Pantelides, Sokrates T.

    2015-11-01

    Ferromagnetism in half-metallic two-dimensional materials can lead to unique spintronics applications. Here we report first-principles calculations that predict monolayer graphyne nanoribbons (GyNRs), an alternative to graphene, doped randomly with 3 d -series transition metal atoms at medium-to-high concentrations (2%-5%) can be ferromagnetic (FM). Furthermore, Mn- and Co-doped GyNRs are half-metallic with 100% spin polarization at the Fermi level and can act as perfect spin filters. The high spin polarization of the current is preserved up to large bias voltages. This study provides a basis for the fabrication of GyNRs with ferromagnetism and spin-polarized electron transport properties.

  4. Tunable spin filter and molecular hybridization in a quantum dot molecule

    NASA Astrophysics Data System (ADS)

    Mireles, F.; Ulloa, S. E.

    2005-03-01

    Spin filtering using few electron semiconductor quantum dots formed in two-dimensional electron gas systems has attracted much recent attention in spintronics. Spin filtering has been achieved in a quantum dot via universal conductance fluctuations and electron magnetic focusing [1]. A bipolar spin filter (SF) has been realized recently using a semiconductor quantum dot which can operate practically as a perfect SF, provided there is a large enough Zeeman splitting [2]. In this work we present calculations showing that the tunable (molecular) hybridization between two quantum dots with few electrons and connected ``in parallel,'' produces a singlet-triplet transition in the ground state which can be used as a robust bipolar SF in both the linear and non-linear regimes of transport. The bipolar SF is found to be fully tunable by only electrical gating at low temperatures. We show that a singlet-triplet transition in the energy spectrum gives rise to the natural spin selectivity in the odd-to-even electron number transition in Coulomb blockade experiments. The competition between the Zeeman, Coulomb, and tunneling energies is studied in detail to determine the optimal conditions to achieve the singlet-triplet transition, so that it becomes broadly useful as a bipolar SF. [1] J. A. Folk et al., Science 299, 679 (2003). [2] R. Hanson et al., cond-mat/0311414 (2003). *Supported by DGAPA-UNAM project 1N114403, CONACYT, projects J40521F and 143673F, and NSF-IMC.

  5. Tunable wavevector and spin filtering in graphene induced by resonant tunneling

    NASA Astrophysics Data System (ADS)

    Lu, Wei-Tao; Li, Wen; Wang, Yong-Long; Jiang, Hua; Xu, Chang-Tan

    2013-08-01

    The resonant tunneling in graphene superlattices with an exchange field is studied theoretically. The results show that a resonant tunneling occurs in the transmission gap by virtue of the transverse wave vector. The position, width, and number of resonant tunneling can be effectively manipulated by adjusting the barrier strength, barrier width, and well width, respectively, which indicates the remarkable wavevector filtering behavior. This resonant effect together with the exchange splitting can be utilized to design an efficient spin filter. It is also found that the energy spectrum in the bound region displays bandlike distribution due to the coupling of eigenstates.

  6. High-Q filters with complete transports using quasiperiodic rings with spin-orbit interaction

    SciTech Connect

    Qiu, R. Z.; Chen, C. H.; Tsao, C. W.; Hsueh, W. J.

    2014-09-15

    A high Q filter with complete transports is achieved using a quasiperiodic Thue-Morse array of mesoscopic rings with spin-orbit interaction. As the generation order of the Thue-Morse array increases, not only does the Q factor of the resonance peak increase exponentially, but the number of sharp resonance peaks also increases. The maximum Q factor for the electronic filter of a Thue-Morse array is much greater than that in a periodic array, for the same number of the rings.

  7. Spinel oxides: 1 spin-filter barrier for a class of magnetic tunnel junctions

    SciTech Connect

    Zhang, J.; Zhang, Xiaoguang; Han, Prof. X. F.

    2012-01-01

    The orbital composition of the electrode wave functions and the complex bands within the barrier band gap are two important factors in deciding the spin-filter effect. This is illustrated in a class of spinel oxides, including MgAl2O4, ZnAl2O4, SiMg2O4, and SiZn2O4. Through first-principles calculations of the complex bands and electron transmission along the [001] direction, they are shown to have the same D1 spin-filter effect as MgO due to the combination of both factors. Due to better lattice match with typical bcc magnetic electrodes than MgO, these materials provide a broad spectrum of candidate materials for magnetic tunnel junctions.

  8. Efficient dipolar double quantum filtering under magic angle spinning without a 1H decoupling field

    NASA Astrophysics Data System (ADS)

    Courtney, Joseph M.; Rienstra, Chad M.

    2016-08-01

    We present a systematic study of dipolar double quantum (DQ) filtering in 13C-labeled organic solids over a range of magic-angle spinning rates, using the SPC-n recoupling sequence element with a range of n symmetry values from 3 to 11. We find that efficient recoupling can be achieved for values n ⩾ 7, provided that the 13C nutation frequency is on the order of 100 kHz or greater. The decoupling-field dependence was investigated and explicit heteronuclear decoupling interference conditions identified. The major determinant of DQ filtering efficiency is the decoupling interference between 13C and 1H fields. For 13C nutation frequencies greater than 75 kHz, optimal performance is observed without an applied 1H field. At spinning rates exceeding 20 kHz, symmetry conditions as low as n = 3 were found to perform adequately.

  9. Efficient dipolar double quantum filtering under magic angle spinning without a (1)H decoupling field.

    PubMed

    Courtney, Joseph M; Rienstra, Chad M

    2016-08-01

    We present a systematic study of dipolar double quantum (DQ) filtering in (13)C-labeled organic solids over a range of magic-angle spinning rates, using the SPC-n recoupling sequence element with a range of n symmetry values from 3 to 11. We find that efficient recoupling can be achieved for values n⩾7, provided that the (13)C nutation frequency is on the order of 100kHz or greater. The decoupling-field dependence was investigated and explicit heteronuclear decoupling interference conditions identified. The major determinant of DQ filtering efficiency is the decoupling interference between (13)C and (1)H fields. For (13)C nutation frequencies greater than 75kHz, optimal performance is observed without an applied (1)H field. At spinning rates exceeding 20kHz, symmetry conditions as low as n=3 were found to perform adequately. PMID:27314744

  10. Studies of 3He+3He, T+3He, and p +D nuclear reactions relevant to stellar or Big-Bang Nucleosynthesis using ICF plasmas at OMEGA

    NASA Astrophysics Data System (ADS)

    Zylstra, Alex; Gatu Johnson, Maria; Frenje, Johan; Li, Chikang; Seguin, Fredrick; Sio, Hong; Rosenberg, Michael; Rinderknecht, Hans; Petrasso, Richard; Herrmann, Hans; Kim, Yong Ho; Hale, Gerry; McNabb, Dennis; Sayre, Dan; Pino, Jesse; Brune, Carl; Bacher, Andy; Forrest, Chad; Glebov, Vladimir; Stoeckl, Christian; Janezic, Roger; Sangster, Craig

    2014-10-01

    The 3He+3He, T+3He, and p +D reactions directly relevant to Stellar or Big-Bang Nucleosynthesis (BBN) have been studied at the OMEGA laser facility using high-temperature low-density `exploding pusher' implosions. The advantage of using these plasmas is that they better mimic astrophysical systems than cold-target accelerator experiments. Measured proton spectra from the 3He3He reaction are used to constrain nuclear R-matrix modeling. The resulting T+3He γ-ray data rule out an anomalously-high 6Li production during BBN as an explanation to the high observed values in primordial material. The proton spectrum from the T+3He reaction is also being used to constrain the R-matrix model. Recent experiments have probed the p +D reaction for the first time in a plasma; this reaction is relevant to energy production in protostars, brown dwarfs and at higher CM energies to BBN. This work was partially supported by the US DOE, NLUF, LLE, and GA.

  11. Strongly bias-dependent tunnel magnetoresistance in manganite spin filter tunnel junctions.

    PubMed

    Prasad, Bhagwati; Zhang, Wenrui; Jian, Jie; Wang, Haiyan; Blamire, Mark G

    2015-05-20

    A highly unconventional bias-dependent tunnel magnetoresistance (TMR) response is observed in Sm0.75 Sr0.25 MnO3 -based nanopillar spin filter tunnel junctions (SFTJs) with two different behaviors in two different thickness regimes of the barrier layer. Thinner barrier devices exhibit conventional SFTJ behaviors; however, for larger barrier thicknesses, the TMR-bias dependence is more complex and reverses sign at higher bias. PMID:25845706

  12. rf Wien filter in an electric dipole moment storage ring: The ``partially frozen spin'' effect

    NASA Astrophysics Data System (ADS)

    Morse, William M.; Orlov, Yuri F.; Semertzidis, Yannis K.

    2013-11-01

    An rf Wien filter (WF) can be used in a storage ring to measure a particle’s electric dipole moment (EDM). If the WF frequency equals the spin precession frequency without WF, and the oscillating WF fields are chosen so that the corresponding transverse Lorentz force equals zero, then a large source of systematic errors is canceled but the EDM signal is not. This effect, discovered by simulation, can be called the “partially frozen spin” effect.

  13. Spinning Spacecraft Attitude Estimation Using Markley Variables: Filter Implementation And Results

    NASA Technical Reports Server (NTRS)

    Sedlak, Joseph E.

    2005-01-01

    Attitude estimation is often more difficult for spinning spacecraft than for three-axis stabilized platforms due to the need to follow rapidly-varying state vector elements and the lack of three-axis rate measurements from gyros. The estimation problem simplifies when torques are negligible and nutation has damped out, but the general case requires a sequential filter with dynamics propagation. This paper describes the implementation and test results for an extended Kalman filter for spinning spacecraft attitude and rate estimation based on a novel set of variables suggested in a paper by Markley [AAS93-3301 (referred to hereafter as Markley variables). Markley has demonstrated that the new set of variables provides a superior parameterization for numerical integration of the attitude dynamics for spinning or momentum-biased spacecraft. The advantage is that the Markley variables have fewer rapidly-varying elements than other representations such as the attitude quaternion and rate vector. A filter based on these variables was expected to show improved performance due to the more accurate numerical state propagation. However, for a variety of test cases, it has been found that the new filter, as currently implemented, does not perform significantly better than a quaternion-based filter that was developed and tested in parallel. This paper reviews the mathematical background for a filter based on Markley variables. It also describes some features of the implementation and presents test results. The test cases are based on a mission using magnetometer and Sun sensor data and gyro measurements on two axes normal to the spin axis. The orbit and attitude scenarios and spacecraft parameters are modeled after one of the THEMIS (Time History of Events and Macroscale Interactions during Substorms) probes. Several tests are presented that demonstrate the filter accuracy and convergence properties. The tests include torque-free motion with various nutation angles, large

  14. Comparative study of nuclear effects in polarized electron scattering from 3He

    DOE PAGESBeta

    Ethier, Jacob James; Melnitchouk, Wally

    2013-11-04

    We present a detailed analysis of nuclear effects in inclusive electron scattering from polarized 3He nuclei for polarization asymmetries, structure functions and their moments, both in the nucleon resonance and deep-inelastic regions. We compare the results of calculations within the weak binding approximation at finite Q2 with the effective polarization ansatz often used in experimental data analyses, and explore the impact of Δ components in the nuclear wave function and nucleon off-shell corrections on extractions of the free neutron structure. Using the same framework we also make predictions for the Q2 dependence of quasielastic scattering from polarized 3He, data onmore » which can be used to constrain the spin-dependent nuclear smearing functions in 3He.« less

  15. A Short History of the Theory and Experimental Discovery of Superfluidity in 3He

    NASA Astrophysics Data System (ADS)

    Brinkman, W. F.

    I discuss the development of the theory and experiments on superfluid 3He. After the discovery of superfluidity in 3He by Osheroff, Richardson and Lee, Phil Anderson quickly recruited Doug Osheroff to come to Bell Labs and set up a dilution fridge to continue his experiments. One of the mysteries at that time was how the high-temperature A-phase, which has a gapless excitation spectrum, could be stabilized relative to the fully gapped, lower temperature B-phase. I explain how Phil Anderson and I developed the spin fluctuation theory of the A-phase of superfluid 3He which accounted for its stability, leading to the Anderson-Brinkman-Morel (ABM) theory of the superfluid A-phase...

  16. Asymmetries in electron-induced breakup of polarized {sup 3}He

    SciTech Connect

    Sirca, S.

    2011-10-24

    The Jefferson Lab Experiment E05-102 'Measurement of A{sub x}{sup '} and A{sub z}{sup '} asymmetries in the quasi-elastic {sup 3}He(e,e'd) reaction' was performed in Hall A in 2009. The main physics motivation of the experiment was to investigate the effects of small components of the {sup 3}He ground-state wave-function by a simultaneous measurement of double-polarization asymmetries in quasi-elastic kinematics for three exclusive channels, (e,e'd), (e,e'p), and (e,e'n), at almost identical momentum transfers, as well as for (e,e'). This experiment will help map the spin structure of the {sup 3}He nucleus onto the picture of the ''free'' polarized neutron. As such, it is of great relevance to the polarized-neutron programs at Jefferson Lab and beyond.

  17. Comparative study of nuclear effects in polarized electron scattering from 3 He

    DOE PAGESBeta

    Ethier, J. J.; Melnitchouk, W.

    2013-11-01

    We present a detailed analysis of nuclear effects in inclusive electron scattering from polarized 3He nuclei for polarization asymmetries, structure functions and their moments, both in the nucleon resonance and deep-inelastic regions. We compare the results of calculations within the weak binding approximation at finite Q2 with the effective polarization ansatz often used in experimental data analyses, and explore the impact of Δ components in the nuclear wave function and nucleon off-shell corrections on extractions of the free neutron structure. Using the same framework we also make predictions for the Q2 dependence of quasielastic scattering from polarized 3He, data onmore » which can be used to constrain the spin-dependent nuclear smearing functions in 3He.« less

  18. Asymmetries in electron-induced breakup of polarized {sup 3}He

    SciTech Connect

    Sirca, Simon

    2011-10-01

    The Jefferson Lab Experiment E05-102 "Measurement of A{sub x}' and A{sub z}' asymmetries in the quasi-elastic {sup 3}He(e,e'd) reaction" was performed in Hall A in 2009. The main physics motivation of the experiment was to investigate the effects of small components of the {sup 3}He ground-state wave-function by a simultaneous measurement of double-polarization asymmetries in quasi-elastic kinematics for three exclusive channels, (e,e'd), (e,e'p), and (e,e'n), at almost identical momentum transfers, as well as for (e,e'). This experiment will help map the spin structure of the {sup 3}He nucleus onto the picture of the "free" polarized neutron. As such, it is of great relevance to the polarized-neutron programs at Jefferson Lab and beyond.

  19. Diffusive transfer of polarized 3He gas through depolarizing magnetic gradients

    NASA Astrophysics Data System (ADS)

    Maxwell, J. D.; Epstein, C. S.; Milner, R. G.

    2015-03-01

    Transfer of polarized 3He gas across spatially varying magnetic fields will facilitate a new source of polarized 3He ions for particle accelerators. In this context, depolarization of atoms as they pass through regions of significant transverse field gradients is a major concern. To understand these depolarization effects, we have built a system consisting of a Helmholtz coil pair and a solenoid, both with central magnetic fields of order 30 gauss. The atoms are polarized via metastability exchange optical pumping in the Helmholtz coil and are in diffusive contact via a glass tube with a second test cell in the solenoid. We have carried out measurements of the spin relaxation during transfer of polarization in 3He at 1 torr by diffusion. We explore the use of measurements of the loss of polarization taken in one cell to infer the polarization in the other cell.

  20. Recycling of 3He from lung magnetic resonance imaging.

    PubMed

    Salhi, Z; Grossmann, T; Gueldner, M; Heil, W; Karpuk, S; Otten, E W; Rudersdorf, D; Surkau, R; Wolf, U

    2012-06-01

    We have developed the means to recycle (3) He exhaled by patients after imaging the lungs using magnetic resonance of hyperpolarized (3) He. The exhaled gas is collected in a helium leak proof bag and further compressed into a steel bottle. The collected gas contains about 1-2% of (3) He, depending on the amount administered and the number of breaths collected to wash out the (3) He gas from the lungs. (3) He is separated from the exhaled air using zeolite molecular sieve adsorbent at 77 K followed by a cold head at 8 K. Residual gaseous impurities are finally absorbed by a commercial nonevaporative getter. The recycled (3) He gas features high purity, which is required for repolarization by metastability exchange optical pumping. At present, we achieve a collection efficiency of 80-84% for exhaled gas from healthy volunteers and cryogenic separation efficiency of 95%. PMID:22135249

  1. Triple quantum filtered spectroscopy of homonuclear three spin-1/2 systems employing isotropic mixing

    NASA Astrophysics Data System (ADS)

    Kirwai, Amey; Chandrakumar, N.

    2016-08-01

    We report the design and performance evaluation of novel pulse sequences for triple quantum filtered spectroscopy in homonuclear three spin-1/2 systems, employing isotropic mixing (IM) to excite triple quantum coherence (TQC). Our approach involves the generation of combination single quantum coherences (cSQC) from antisymmetric longitudinal or transverse magnetization components employing isotropic mixing (IM). cSQC's are then converted to TQC by a selective 180° pulse on one of the spins. As IM ideally causes magnetization to evolve under the influence of the spin coupling Hamiltonian alone, TQC is generated at a faster rate compared to sequences involving free precession. This is expected to be significant when the spins have large relaxation rates. Our approach is demonstrated experimentally by TQC filtered 1D spectroscopy on a 1H AX2 system (propargyl bromide in the presence of a paramagnetic additive), as well as a 31P linear AMX system (ATP in agar gel). The performance of the IM-based sequences for TQC excitation are compared against the standard three pulse sequence (Ernst et al., 1987) and an AX2 spin pattern recognition sequence (Levitt and Ernst, 1983). The latter reaches the unitary bound on TQC preparation efficiency starting from thermal equilibrium in AX2 systems, not considering relaxation. It is shown that in systems where spins relax rapidly, the new IM-based sequences indeed perform significantly better than the above two known TQC excitation sequences, the sensitivity enhancement being especially pronounced in the case of the proton system investigated. An overview of the differences in relaxation behavior is presented for the different approaches. Applications are envisaged to Overhauser DNP experiments and to in vivo NMR.

  2. Triple quantum filtered spectroscopy of homonuclear three spin-1/2 systems employing isotropic mixing.

    PubMed

    Kirwai, Amey; Chandrakumar, N

    2016-08-01

    We report the design and performance evaluation of novel pulse sequences for triple quantum filtered spectroscopy in homonuclear three spin-1/2 systems, employing isotropic mixing (IM) to excite triple quantum coherence (TQC). Our approach involves the generation of combination single quantum coherences (cSQC) from antisymmetric longitudinal or transverse magnetization components employing isotropic mixing (IM). cSQC's are then converted to TQC by a selective 180° pulse on one of the spins. As IM ideally causes magnetization to evolve under the influence of the spin coupling Hamiltonian alone, TQC is generated at a faster rate compared to sequences involving free precession. This is expected to be significant when the spins have large relaxation rates. Our approach is demonstrated experimentally by TQC filtered 1D spectroscopy on a (1)H AX2 system (propargyl bromide in the presence of a paramagnetic additive), as well as a (31)P linear AMX system (ATP in agar gel). The performance of the IM-based sequences for TQC excitation are compared against the standard three pulse sequence (Ernst et al., 1987) and an AX2 spin pattern recognition sequence (Levitt and Ernst, 1983). The latter reaches the unitary bound on TQC preparation efficiency starting from thermal equilibrium in AX2 systems, not considering relaxation. It is shown that in systems where spins relax rapidly, the new IM-based sequences indeed perform significantly better than the above two known TQC excitation sequences, the sensitivity enhancement being especially pronounced in the case of the proton system investigated. An overview of the differences in relaxation behavior is presented for the different approaches. Applications are envisaged to Overhauser DNP experiments and to in vivo NMR. PMID:27253727

  3. A System for Open-Access 3He Human Lung Imaging at Very Low Field

    PubMed Central

    RUSET, I.C.; TSAI, L.L.; MAIR, R.W.; PATZ, S.; HROVAT, M.I.; ROSEN, M.S.; MURADIAN, I.; NG, J.; TOPULOS, G.P.; BUTLER, J.P.; WALSWORTH, R.L.; HERSMAN, F.W.

    2010-01-01

    We describe a prototype system built to allow open-access very-low-field MRI of human lungs using laser-polarized 3He gas. The system employs an open four-coil electromagnet with an operational B0 field of 4 mT, and planar gradient coils that generate gradient fields up to 0.18 G/cm in the x and y direction and 0.41 G/cm in the z direction. This system was used to obtain 1H and 3He phantom images and supine and upright 3He images of human lungs. We include discussion on challenges unique to imaging at 50 –200 kHz, including noise filtering and compensation for narrow-bandwidth coils. PMID:20354575

  4. /sup 3/He functions in tokamak-pumped laser systems

    SciTech Connect

    Jassby, D.L.

    1986-10-01

    /sup 3/He placed in an annular cell around a tokamak fusion generator can convert moderated fusion neutrons to energetic ions by the /sup 3/He(n,p)T reaction, and thereby excite gaseous lasants mixed with the /sup 3/He while simultaneously breeding tritium. The total /sup 3/He inventory is about 4 kg for large tokamak devices. Special configurations of toroidal-field magnets, neutron moderators and beryllium reflectors are required to permit nearly uniform neutron current into the laser cell with minimal attenuation. The annular laser radiation can be combined into a single output beam at the top of the tokamak.

  5. Andreev reflection in rotating superfluid {sup 3}He-B

    SciTech Connect

    Eltsov, V. B.; Hosio, J. J.; Krusius, M. Mäkinen, J. T.

    2014-12-15

    Andreev reflection of quasiparticle excitations from quantized line vortices is reviewed in the isotropic B phase of superfluid {sup 3}He in the temperature regime of ballistic quasiparticle transport at T ≤ 0.20T{sub c}. The reflection from an array of rectilinear vortices in solid-body rotation is measured with a quasiparticle beam illuminating the array mainly in the orientation along the rotation axis. The result is in agreement with the calculated Andreev reflection. The Andreev signal is also used to analyze the spin-down of the superfluid component after a sudden impulsive stop of rotation from an equilibrium vortex state. In a measuring setup where the rotating cylinder has a rough bottom surface, annihilation of the vortices proceeds via a leading rapid turbulent burst followed by a trailing slow laminar decay, from which the mutual friction dissipation can be determined. In contrast to the currently accepted theory, it is found to have a finite value in the zero-temperature limit: α(T→0) = (5 ± 0.5) × 10{sup −4}.

  6. Results on Double-polarization Asymmetries in Quasielastic Scattering from Polarized 3He

    NASA Astrophysics Data System (ADS)

    Sulkosky, Vincent A.

    2016-03-01

    The 3He nucleus has become extremely important in the investigation of the neutron's spin structure. When polarized, 3He acts as an effective polarized neutron target and hence facilitates our understanding of the neutron's internal structure. However, to be used in this manner, our understanding of the internal structure of 3He is of extreme importance. As the precision of experiments has improved, the extraction of polarized neutron information from 3He leads to an ever larger share of the systematic uncertainty for these experiments. In these proceedings, I present a precise measurement of beam-target asymmetries in the {}^3overrightarrow {He} (e,e'd) and {}^3overrightarrow {He} (e,e'p) reactions. The former process is a uniquely sensitive probe of hadron dynamics in 3He and the structure of the underlying electromagnetic currents. The measurements have been performed around the quasi-elastic peak at Q2 = 0.25 (GeV/c)2 and 0.35 (GeV/c)2 for recoil momenta up to 270 MeV/c. The experimental apparatus, analysis and results were presented together with a comparison to state-of-the art Faddeev calculations.

  7. Spin filter effect at room temperature in GaN/GaMnN ferromagnetic resonant tunnelling diode

    NASA Astrophysics Data System (ADS)

    Wójcik, P.; Adamowski, J.; Wołoszyn, M.; Spisak, B. J.

    2013-06-01

    We have investigated the spin current polarization without the external magnetic field in the resonant tunneling diode with the emitter and quantum well layers made from the ferromagnetic GaMnN. For this purpose, we have applied the self-consistent Wigner-Poisson method and studied the spin-polarizing effect for the parallel and antiparallel alignments of the magnetization of the ferromagnetic layers. The results of our calculations show that the antiparallel magnetization is much more advantageous for the spin filter operation and leads to the full spin current polarization at low temperatures and 35% spin polarization of the current at room temperature.

  8. Efficient spin-filter and negative differential resistance behaviors in FeN4 embedded graphene nanoribbon device

    NASA Astrophysics Data System (ADS)

    Liu, N.; Liu, J. B.; Yao, K. L.; Ni, Y.; Wang, S. L.

    2016-03-01

    In this paper, we propose a new device of spintronics by embedding two FeN4 molecules into armchair graphene nanoribbon and sandwiching them between N-doped graphene nanoribbon electrodes. Our first-principle quantum transport calculations show that the device is a perfect spin filter with high spin-polarizations both in parallel configuration (PC) and antiparallel configuration (APC). Moreover, negative differential resistance phenomena are obtained for the spin-down current in PC, and the spin-up and spin-down currents in APC. These transport properties are explained by the bias-dependent evolution of molecular orbitals and the transmission spectra.

  9. A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas.

    PubMed

    López, Alexander; Medina, Ernesto; Bolívar, Nelson; Berche, Bertrand

    2010-03-24

    A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions. PMID:21389461

  10. In situ polarized 3He system for the Magnetism Reflectometer at the Spallation Neutron Source.

    PubMed

    Tong, X; Jiang, C Y; Lauter, V; Ambaye, H; Brown, D; Crow, L; Gentile, T R; Goyette, R; Lee, W T; Parizzi, A; Robertson, J L

    2012-07-01

    We report on the in situ polarized (3)He neutron polarization analyzer developed for the time-of-flight Magnetism Reflectometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Using the spin exchange optical pumping method, we achieved a (3)He polarization of 76% ± 1% and maintained it for the entire three-day duration of the test experiment. Based on transmission measurements with unpolarized neutrons, we show that the average analyzing efficiency of the (3)He system is 98% for the neutron wavelength band of 2-5 Å. Using a highly polarized incident neutron beam produced by a supermirror bender polarizer, we obtained a flipping ratio of >100 with a transmission of 25% for polarized neutrons, averaged over the wavelength band of 2-5 Å. After the cell was depolarized for transmission measurements, it was reproducibly polarized and this performance was maintained for three weeks. A high quality polarization analysis experiment was performed on a reference sample of Fe/Cr multilayer with strong spin-flip off-specular scattering. Using a combination of the position sensitive detector, time-of-flight method, and the excellent parameters of the (3)He cell, the polarization analysis of the two-dimensional maps of reflected, refracted, and off-specular scattered intensity above and below the horizon were obtained, simultaneously. PMID:22852718

  11. Designing of spin-filtering devices in zigzag graphene nanoribbons heterojunctions by asymmetric hydrogenation and B-N doping

    SciTech Connect

    Zhang, Dan; Zhang, Xiaojiao; Ouyang, Fangping; Li, Mingjun; Xu, Hui; Long, Mengqiu

    2015-01-07

    Using nonequilibrium Green's function in combination with the spin-polarized density functional theory, the spin-dependent transport properties of boron and nitrogen doped zigzag graphene nanoribbons (ZGNRs) heterojunctions with single or double edge-saturated hydrogen have been investigated. Our results show that the perfect spin-filtering effect (100%), rectifying behavior and negative differential resistance can be realized in the ZGNRs-based systems. And the corresponding physical analysis has been given.

  12. Spin-wave band-pass filters based on yttrium iron garnet films for tunable microwave photonic oscillators

    NASA Astrophysics Data System (ADS)

    Ustinov, A. B.; Drozdovskii, A. V.; Nikitin, A. A.; Kalinikos, B. A.

    2015-12-01

    The paper reports on development of tunable band-pass microwave filters for microwave photonic generators. The filters were fabricated with the use of epitaxial yttrium iron garnet films. Principle of operation of the filters was based on excitation, propagation, and reception of spin waves. In order to obtain narrow pass band, the filtering properties of excitation and reception antennas were exploited. The filters demonstrated insertion losses of 2-3 dB, bandwidth of 25-35 MHz, and tuning range of up to 1.5 GHz in the range 3-7 GHz.

  13. CFD simulation of an internal spin-filter: evidence of lateral migration and exchange flow through the mesh.

    PubMed

    Figueredo-Cardero, Alvio; Chico, Ernesto; Castilho, Leda R; Medronho, Ricardo A

    2009-11-01

    In the present work Computational Fluid Dynamics (CFD) was used to study the flow field and particle dynamics in an internal spin-filter (SF) bioreactor system. Evidence of a radial exchange flow through the filter mesh was detected, with a magnitude up to 130-fold higher than the perfusion flow, thus significantly contributing to radial drag. The exchange flow magnitude was significantly influenced by the filter rotation rate, but not by the perfusion flow, within the ranges evaluated. Previous reports had only given indirect evidences of this exchange flow phenomenon in spin-filters, but the current simulations were able to quantify and explain it. Flow pattern inside the spin-filter bioreactor resembled a typical Taylor-Couette flow, with vortices being formed in the annular gap and eventually penetrating the internal volume of the filter, thus being the probable reason for the significant exchange flow observed. The simulations also showed that cells become depleted in the vicinity of the mesh due to lateral particle migration. Cell concentration near the filter was approximately 50% of the bulk concentration, explaining why cell separation achieved in SFs is not solely due to size exclusion. The results presented indicate the power of CFD techniques to study and better understand spin-filter systems, aiming at the establishment of effective design, operation and scale-up criteria. PMID:19998058

  14. Effective spin-orbit couplings in an analytical tight-binding model of DNA: Spin filtering and chiral spin transport

    NASA Astrophysics Data System (ADS)

    Varela, Solmar; Mujica, Vladimiro; Medina, Ernesto

    2016-04-01

    We derive a detailed analytical tight-binding (TB) model for a double helix emulating DNA with one type of nucleotide pair and a single oriented π orbital per base. The TB model incorporates both kinetic and intrinsic spin-orbit (ISO) contributions as well as Rashba-type interactions coupled to an external electric field along the axis of the double helix. The helical structure of the molecule renders the ISO first order in the interaction strength (in the meV range) as in carbon nanotubes. The coupling between the ISO and the chirality of the molecule is manifest in the effective coupling parameters while the Rashba coupling is only weakly dependent on structural chirality. A continuum model at half filling is derived where the dispersion is linear around the Fermi level. Spin transport can be completely solved in the case of ISO and the dominant Rashba type term. Spin selectivity is shown to exist for this minimal model (with features similar to recent experimental findings) when the double helix is biased and thus time reversal symmetry is broken. The model also display robustness toward scattering because of the chiral nature of the eigenstates.

  15. Dynamic spin filtering at the Co/Alq3 interface mediated by weakly coupled second layer molecules.

    PubMed

    Droghetti, Andrea; Thielen, Philip; Rungger, Ivan; Haag, Norman; Großmann, Nicolas; Stöckl, Johannes; Stadtmüller, Benjamin; Aeschlimann, Martin; Sanvito, Stefano; Cinchetti, Mirko

    2016-01-01

    Spin filtering at organic-metal interfaces is often determined by the details of the interaction between the organic molecules and the inorganic magnets used as electrodes. Here we demonstrate a spin-filtering mechanism based on the dynamical spin relaxation of the long-living interface states formed by the magnet and weakly physisorbed molecules. We investigate the case of Alq3 on Co and, by combining two-photon photoemission experiments with electronic structure theory, show that the observed long-time spin-dependent electron dynamics is driven by molecules in the second organic layer. The interface states formed by physisorbed molecules are not spin-split, but acquire a spin-dependent lifetime, that is the result of dynamical spin-relaxation driven by the interaction with the Co substrate. Such spin-filtering mechanism has an important role in the injection of spin-polarized carriers across the interface and their successive hopping diffusion into successive molecular layers of molecular spintronics devices. PMID:27578395

  16. Magnon Condensation into a Q Ball in {sup 3}He-B

    SciTech Connect

    Bunkov, Yu. M.; Volovik, G. E.

    2007-06-29

    The theoretical prediction of Q balls in relativistic quantum fields is realized here experimentally in superfluid {sup 3}He-B. The condensed-matter analogs of relativistic Q balls are responsible for an extremely long-lived signal of magnetic induction observed in NMR at the lowest temperatures. This Q ball is another representative of a state with phase coherent precession of nuclear spins in {sup 3}He-B, similar to the well-known homogeneously precessing domain, which we interpret as Bose-Einstein condensation of spin waves--magnons. At large charge Q, the effect of self-localization is observed. In the language of relativistic quantum fields it is caused by interaction between the charged and neutral fields, where the neutral field provides the potential for the charged one. In the process of self-localization the charged field modifies locally the neutral field so that the potential well is formed in which the charge Q is condensed.

  17. Theory of (3He,(alpha)) surrogate reactions for deformed uranium nuclei

    SciTech Connect

    Thompson, I; Escher, J E

    2006-11-08

    We present the one-step theory of neutron-pickup transfer reactions with {sup 3}He projectiles on {sup 235}U and {sup 238}U. We find all the neutron eigenstates in a deformed potential, and use those in a given energy range for ({sup 3}He, {alpha}) DWBA pickup calculations to find the spin and parity distributions of the residual target nuclei. A simple smoothing convolution is used to take into account the spreading width of the single-neutron hole states into the more complicated compound nuclear states. We assume that the initial target is an even-even rotor, but can take into account spectator neutrons outside such a rotor by recombining their spin and parity at the end of the calculations.

  18. Magnon condensation into a Q ball in 3He-B.

    PubMed

    Bunkov, Yu M; Volovik, G E

    2007-06-29

    The theoretical prediction of Q balls in relativistic quantum fields is realized here experimentally in superfluid 3He-B. The condensed-matter analogs of relativistic Q balls are responsible for an extremely long-lived signal of magnetic induction observed in NMR at the lowest temperatures. This Q ball is another representative of a state with phase coherent precession of nuclear spins in 3He-B, similar to the well-known homogeneously precessing domain, which we interpret as Bose-Einstein condensation of spin waves--magnons. At large charge Q, the effect of self-localization is observed. In the language of relativistic quantum fields it is caused by interaction between the charged and neutral fields, where the neutral field provides the potential for the charged one. In the process of self-localization the charged field modifies locally the neutral field so that the potential well is formed in which the charge Q is condensed. PMID:17678101

  19. A Light-Front Approach to the 3He Spectral Function

    NASA Astrophysics Data System (ADS)

    Scopetta, Sergio; Del Dotto, Alessio; Kaptari, Leonid; Pace, Emanuele; Rinaldi, Matteo; Salmè, Giovanni

    2015-09-01

    The analysis of semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, aimed at the extraction of the quark transverse-momentum distributions in the neutron, requires the use of a distorted spin-dependent spectral function for 3He, which takes care of the final state interaction effects. This quantity is introduced in the non-relativistic case, and its generalization in a Poincaré covariant framework, in plane wave impulse approximation for the moment being, is outlined. Studying the light-front spin-dependent spectral function for a J = 1/2 system, such as the nucleon, it is found that, within the light-front dynamics with a fixed number of constituents and in the valence approximation, only three of the six leading twist T-even transverse-momentum distributions are independent.

  20. Polarized 3He as an effective neutron target for deep inelastic scattering

    NASA Astrophysics Data System (ADS)

    Johnston, Kyle

    In undergraduate physics courses, we are all taught that a proton and a neutron both have a quantity called 'spin' which has a simple value of 1/2 in units of h. It was first naively understood that this value comes from the addition of the spins of the basic constituents, quarks and gluons. However, experiments revealed that it is not enough. The value of 1/2 has yet to be reconciled with the addition of not only the spins of the constituents but also their orbital motion. Clearly, the spin structure in terms of the basic constituents needs more investigation. This thesis aims to describe the polarization and calibration of a polarized 3He target, which can be used for probing the spin structure of the neutron in terms of its constituents, quarks and gluons.

  1. A New 3He-Target Design for Compton Scattering Experiment

    NASA Astrophysics Data System (ADS)

    Mahalchick, S.; Gao, H.; Laskaris, G.; Weir, W.; Ye, Q.; Ye, Q. J.

    2011-10-01

    The neutron spin polarizabilities describe the stiffness of the neutron spin to external electric and magnetic fields. A double-polarized elastic Compton Scattering experiment will try to determine the neutron spin polarizabilities using a new polarized 3He target and the circularly polarized γ-beam of HI γS facility at the Duke Free Electron Laser Laboratory (DFELL). To polarize the 3He target, a newly constructed solenoid is being used which can provide a very uniform magnetic field around the target area and allows to place High Intensity Gamma Source NaI Detector Arrays (HINDA) closer to the target. The ideal target polarization is 40-60% and will be measured using the nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) techniques. A prototype of the polarized 3He target is being constructed in the Medium Energy Physics Group laboratories at Duke and is currently being tested. The experiment is expected to take place in 2013 after the DFELL upgrade. I will be presenting details of the construction process, including design specifications and data from the magnetic field mapping, as well as preliminary target polarization results. This work is supported by the US Department of Energy, under contract number DE-FG02-03ER41231, and by the National Science Foundation, grant number NSF-PHY-08-51813.

  2. The Effects of Hybrid Optical Pumping on the Electron Spin Filter.

    NASA Astrophysics Data System (ADS)

    Rosenberry, Mark; Gay, Timothy

    2016-05-01

    Under the low pressure conditions of our spin filter experiment, optically pumping a single alkali species runs into the problem of radiation trapping. To polarize a significant electron current requires a moderate alkali density, but in the absence of quenching effects such a vapor is limited to modest polarization, and hence the resulting electron polarization is also low. One possible solution is to introduce a second alkali species, which can be polarized by spin exchange with the laser polarized species. Since this second species does not interact with the laser, it does not suffer from radiation trapping, even if it has a substantial density. We report progress in experimental and computational studies of potassium/rubidium hybrid pumping in this regime

  3. The H and D Polarized Target for Spin-Filtering Measurements at COSY

    NASA Astrophysics Data System (ADS)

    Ciullo, Giuseppe; Statera, Marco; Lenisa, Paolo; Nass, Alexander; Tagliente, Giuseppe

    2016-04-01

    In the main frame of the PAX (Polarized Antiproton eXperiments) collaboration, which engaged the challenging purpose of polarizing antiproton beams, the possibility to have H or D polarized targets requires a daily switchable source and its diagnostics: mainly change is a dual cavity tunable for H and D. The commissioning of PAX has been fullfilled, for the transverse case, on the COSY (COoler SYnchrotron) proton ring, achieving milestones on spin-dependent cross-section measurements. Now the longitudinal case could provide sensitive polarization results. An H or D source allows the exploration of the spin-filtering process with a deuterium polarized target, and opens new chances for testing Time Reversal Invariance at COSY (TRIC).

  4. Bi-layer ^3He: a simple two dimensional heavy fermion system with quantum criticality

    NASA Astrophysics Data System (ADS)

    Saunders, John

    2008-03-01

    Two dimensional helium films provide simple model systems for the investigation of quantum phase transitions in two dimensions. Monolayer ^3He absorbed on graphite, with various pre-platings, behaves as a two dimensional Mott-Hubbard system, complete with a density driven ``metal-insulator'' transition [1, 2] into what appears to be a gapless spin-liquid. In two dimensions the corrections to the temperature dependence of the fluid heat capacity, beyond the term linear in T, are anomalous and attributed to quasi-1D scattering [3]. On the other hand, bi-layer ^3He films adsorbed on the surface of graphite show evidence of two-band heavy-fermion behavior and quantum criticality [4, 5]. The relevant control parameter is the total density of the ^3He film. The ^3He bilayer system can be driven toward a quantum critical point (QCP) at which the effective mass appears to diverge, the effective inter-band hybridization vanishes, and a local moment state appears. A theoretical model in terms of a ``Kondo breakdown selective Mott transition'' has recently been suggested [6]. * In collaboration with: A Casey, M Neumann, J Nyeki, B Cowan. [1] Evidence for a Mott-Hubbard Transition in a Two-Dimensional ^3He Fluid Monolayer, A. Casey, H. Patel, J. Ny'eki, B. P. Cowan, and J. Saunders Phys. Rev. Lett. 90, 115301 (2003) [2] D Tsuji et al. J. Low Temp. Phys. 134, 31 (2004) [3] A V Chubukov et al. Phys. Rev. B71, 205112 (2005) [4] Bilayer ^3He; a simple two dimensional heavy fermion system with quantum criticality, Michael Neumann, Jan Nyeki, Brian Cowan, John Saunders. Science 317, 1356 (2007) [5] Heavy fermions in the original Fermi liquid. Christopher A Hooley and Andrew P Mackenzie. Science 317, 1332 (2007) [6] C Pepin, Phys. Rev. Lett. 98, 206401 (2007) and A Benlagra and C Pepin, arXiv: 0709.0354

  5. Spin currents and filtering behavior in zigzag graphene nanoribbons with adsorbed molybdenum chains

    NASA Astrophysics Data System (ADS)

    García-Fuente, A.; Gallego, L. J.; Vega, A.

    2015-04-01

    By means of density-functional-theoretic calculations, we investigated the structural, electronic and transport properties of hydrogen-passivated zigzag graphene nanoribbons (ZGNRs) on which a one-atom-thick Mo chain was adsorbed (with or without one or two missing atoms), or in which the passivating hydrogen atoms were replaced by Mo atoms. Mo-passivated ZGNRs proved to be nonmagnetic. ZGNRs with an adsorbed defect-free Mo chain were most stable with the Mo atoms forming dimers above edge bay sites, which suppressed the magnetic moments of the C atoms in that half of the ribbon; around the Fermi level of these systems, each spin component had a transmission channel via the Mo spz band and one had an additional channel created by polarization of the ZGNR π* band, leading to a net spin current. The absence of an Mo dimer from an Mo chain adsorbed at the ZGNR edge made the system a perfect spin filter at low voltage bias by suppressing the Mo spz band channels. Thus this last kind of hybrid system is a potential spin valve.

  6. Spin coating of ZnS nanostructures on filter paper and their characterization

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Purohit, L. P.; Goswami, Y. C.

    2016-09-01

    In this paper we have reported spin coating of Cu doped Zinc sulphide nanostructures on filter paper flexible substrates. Zinc chloride and thiourea were used as precursors of zinc and sulphur. The samples were characterized by XRD, FE-SEM, EDAX and UV-visible spectrum studies. All the diffractogram peaks confirm the cubic structure of ZnS with small peak of Cu indicates incorporation of Cu into ZnS lattice. FE-SEM micrographs exhibit fibrous morphologies of ZnS structures on filter paper. Compound structures on flexible substrates show ohmic behavior with conductivity about 3.07×106 (Ωcm)-1 to 4.27×106 (Ωcm)-1. Excellent photoluminescence property doped with copper makes them suitable for flexible opto-electronic devices.

  7. Bipolar spin-filtering effect in B- or N-doped zigzag graphene nanoribbons with asymmetric edge hydrogenation

    NASA Astrophysics Data System (ADS)

    Wang, Li-hua; Zhang, Zi-zhen; Zhao, Jian-Guo; Ding, Bing-jun; Guo, Yong; Jin, Chun

    2015-11-01

    The spin transport properties of zigzag graphene nanoribbon (ZGNR) hetero-junctions, in which ZGNR electrodes are doped with B or N atoms, are investigated based on spin-polarized density functional theory and non-equilibrium Green's function. ZGNRs are C-H2 bonded at one edge and C-H bonded at the other edge to form asymmetric edge hydrogenation. The spin-polarized currents of ZGNR-based nano-devices with an odd or even number of the zigzag-shaped chains show a perfect bipolar spin-filtering effect on parallel and anti-parallel magnetic configurations. This study provides insights into the design of high-performance graphene-based spin filters.

  8. The Unusual Behavior of Solar Wind 3He++

    NASA Astrophysics Data System (ADS)

    Gloeckler, George; Fisk, L. A.; Geiss, J.

    2016-07-01

    The first measurements of the isotopic ratio of solar wind He by the Apollo SWC experiment revealed that 3He/4He is not constant, but varies from ˜~4•10-4 to ˜~5.5•10-4. Such variations are modest compared with the 3He/4He variations often seen in Helium-3 rich SEP events. Here we report and compare detailed measurements with ACE/SWICS of the densities, bulk speeds and thermal speeds of solar wind 1H+, 4He++ and 3He++ during one Carrington rotation (in January 2005). The most remarkable finding is the factor of ˜~100 variation in the solar wind 3He++/4He++ number density ratio from a low value of ˜~5•10-5 to a high value of ˜~6•10-3. The highest ratios occurred during four time intervals of one to two days each. Large ratios are observed during periods of low (< ˜~20 km/s) 3He++ thermal speeds and when the bulk speeds as well as the thermal speeds of 1H+, 4He++ and 3He++ are almost the same. Small ratios, on the other hand, were found when the spread between the thermal speeds as well as between the bulk speeds of 1H+, 4He++ and 3He++ was large. During times of small 3He++/4He++ ratios the thermal speed of 3He++ was above 20 km/s, and the proton and 4He++ thermal speeds exceeded ˜~50 km/s and ˜~35 km/s, respectively. We will examine additional time periods to determine whether the compositional variations of solar wind helium during this particular Carrington rotation are unusual or common, and will speculate on possible mechanisms that could produce the factor of 100 variations in the isotopic solar wind He ratio.

  9. Neutron Detection Alternatives to 3He for National Security Applications

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Erikson, Luke E.; Kernan, Warnick J.; Lintereur, Azaree T.; Siciliano, Edward R.; Stephens, Daniel L.; Stromswold, David C.; Van Ginhoven, Renee M.; Woodring, Mitchell L.

    2010-11-21

    One of the main uses for 3He is in gas proportional counters for neutron detection. Large radiation detection systems deployed for homeland security and proliferation detection applications use such systems. Due to the large increase in use of 3He for homeland security and basic research, the supply has dwindled, and can no longer meet the demand. This has led to the search for an alternative technology to replace the use of 3He-based neutron detectors. In this paper, we review the testing of currently commercially available alternative technologies for neutron detection in large systems used in various national security applications.

  10. Shear Modulus and Dislocations in bcc Solid ^3He

    NASA Astrophysics Data System (ADS)

    Cheng, Zhi Gang; Souris, Fabien; Beamish, John

    2016-05-01

    The shear modulus of hcp ^4He decreases significantly above ˜ 200 mK, as ^3He impurities unbind from dislocations, unpinning them, and softening the crystal. Here we report shear modulus measurements on a fermi quantum solid: bcc ^3He. In contrast to previous low-frequency measurements, which did not show dislocation softening in this system, we have observed a drop in shear modulus, accompanied by a dissipation peak, which we attribute to the unpinning of dislocations as ^4He impurities unbind. For large stresses, impurities cannot pin the dislocations and the low temperature stiffening is suppressed. At high frequencies, the modulus changes and dissipation peaks shift to higher temperature, indicating that the unbinding is thermally activated. For a 58 bar bcc ^3He crystal, we find an activation energy of 0.27 K, smaller than the 0.7 K binding energy for ^3He impurities in hcp ^4He.

  11. Zeeman relaxation of cold atomic iron and nickel in collisions with {sup 3}He

    SciTech Connect

    Johnson, Cort; Newman, Bonna; Kleppner, Daniel; Greytak, Thomas J.; Brahms, Nathan; Doyle, John M.

    2010-06-15

    We have measured the ratio {gamma} of the diffusion cross section to the angular momentum reorientation cross section in the colliding Fe-{sup 3}He and Ni-{sup 3}He systems. Nickel (Ni) and iron (Fe) atoms are introduced via laser ablation into a cryogenically cooled experimental cell containing cold (<1 K) {sup 3}He buffer gas. Elastic collisions rapidly cool the translational temperature of the ablated atoms to the {sup 3}He temperature. {gamma} is extracted by measuring the decays of the atomic Zeeman sublevels. For our experimental conditions, thermal energy is comparable to the Zeeman splitting. As a result, thermal excitations between Zeeman sublevels significantly impact the observed decay. To determine {gamma} accurately, we introduce a model of Zeeman-state dynamics that includes thermal excitations. We find {gamma}{sub Ni-}{sup 3}{sub He}=5x10{sup 3} and {gamma}{sub Fe-}{sup 3}{sub He{<=}}3x10{sup 3} at 0.75 K in a 0.8-T magnetic field. These measurements are interpreted in the context of submerged shell suppression of spin relaxation, as studied previously in transition metals and rare-earth-metal atoms [C. I. Hancox, S. C. Doret, M. T. Hummon, R. V. Krems, and J. M. Doyle, Phys. Rev. Lett. 94, 013201 (2005); C. I. Hancox, S. C. Doret, M. T. Hummon, L. Luo, and J. M. Doyle, Nature (London) 431, 281 (2004); A. Buchachenko, G. Chaasiski, and M. Szczniak, Eur. Phys. J. D 45, 147 (2007)].

  12. Torsion Pendulum Experiments with Superfluid 3He in ``Nematically Ordered'' Aerogel

    NASA Astrophysics Data System (ADS)

    Zhelev, Nikolay; Smith, Eric; Sebastian, Abhilash; Parpia, Jeevak

    2014-03-01

    A new type of highly anisotropic alumina aerogel is used to induce directional disorder in superfluid 3He. The aerogel sample consists of a network of long strands that have a preferred orientation (nematic order). It is placed in the head of a double torsion pendulum with the anisotropy axis oriented along the axis of the pendulum. We observe the frequency shift of the symmetric torsion mode of the pendulum in order to determine the superfluid fraction of the embedded 3He. The superfluid transition temperature of the fluid in the aerogel is measured to be very close to that of bulk 3He. However, in contrast to the bulk phase diagram, the region of stability of the Equal Spin Pairing (ESP) superfluid phase is enhanced on cooling. In addition, unlike the case of 3He in isotropic silica aerogel, the ESP phase reappears on warming. We compare our measurements to the NMR data reported in and discuss the possible structure of the observed superfluid phases.

  13. Surface Majorana fermions and bulk collective modes in superfluid 3He-B

    NASA Astrophysics Data System (ADS)

    Park, YeJe; Chung, Suk Bum; Maciejko, Joseph

    2015-02-01

    The theoretical study of topological superfluids and superconductors has so far been carried out largely as a translation of the theory of noninteracting topological insulators into the superfluid language, whereby one replaces electrons by Bogoliubov quasiparticles and single-particle band Hamiltonians by Bogoliubov-de Gennes Hamiltonians. Band insulators and superfluids are, however, fundamentally different: While the former exist in the absence of interparticle interactions, the latter are broken symmetry states that owe their very existence to such interactions. In particular, unlike the static energy gap of a band insulator, the gap in a superfluid is due to a dynamical order parameter that is subject to both thermal and quantum fluctuations. In this work, we explore the consequences of bulk quantum fluctuations of the order parameter in the B phase of superfluid 3He on the topologically protected Majorana surface states. Neglecting the high-energy amplitude modes, we find that one of the three spin-orbit Goldstone modes in 3He-B couples to the surface Majorana fermions. This coupling in turn induces an effective short-range two-body interaction between the Majorana fermions, with coupling constant inversely proportional to the strength of the nuclear dipole-dipole interaction in bulk 3He. A mean-field theory suggests that the surface Majorana fermions in 3He-B may be in the vicinity of a metastable gapped time-reversal-symmetry-breaking phase.

  14. The overview and early measurements from the n 3He experiment

    NASA Astrophysics Data System (ADS)

    Garishvili, Garishvili; n3 HE Collaboration

    2015-04-01

    The main goal of the n 3He experiment at the Spallation Neutron Source (SNS) at ORNL is to perform a precise measurement of the parity violating (PV) weak amplitude of the reaction n->+3 He --> T + p + 765 KeV. In particular, the goal is to measure the spatial asymmetry of emitted protons with respect to the neutron spin direction. This asymmetry is expected to be very small (<10-7) since the NN interaction is dominated by the parity conserving (PC) strong amplitude. The final goal is to measure the asymmetry in the n 3He experiment with an accuracy of ~ 2 ×10-8 to isolate the I=0 components of the hadronic weak interaction, which is vital for constraining weak coupling constants predicted by theory. The n 3He detector was installed and commissioned in December 2014 on the Fundamental Neutron Physics Beamline at the SNS. Production data taking is expected to start by the end of January 2015 and planned to run until the end of 2015. The status of the experiment will be presented, including early data.

  15. Polar Phase of Superfluid (3)He in Anisotropic Aerogel.

    PubMed

    Dmitriev, V V; Senin, A A; Soldatov, A A; Yudin, A N

    2015-10-16

    We report the first observation of the polar phase of superfluid (3)He. This phase appears in (3)He confined in a new type of aerogel with a nearly parallel arrangement of strands which play the role of ordered impurities. Our experiments qualitatively agree with theoretical predictions and suggest that in other systems with unconventional Cooper pairing (e.g., in unconventional superconductors) similar phenomena may be found in the presence of anisotropic impurities. PMID:26550884

  16. Interface Engineering to Create a Strong Spin Filter Contact to Silicon.

    PubMed

    Caspers, C; Gloskovskii, A; Gorgoi, M; Besson, C; Luysberg, M; Rushchanskii, K Z; Ležaić, M; Fadley, C S; Drube, W; Müller, M

    2016-01-01

    Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on silicon is a perfect route to enrich silicon nanotechnology with spin filter functionality. To date, the inherent chemical reactivity between EuO and Si has prevented a heteroepitaxial integration without significant contaminations of the interface with Eu silicides and Si oxides. We present a solution to this long-standing problem by applying two complementary passivation techniques for the reactive EuO/Si interface: (i) an in situ hydrogen-Si (001) passivation and (ii) the application of oxygen-protective Eu monolayers-without using any additional buffer layers. By careful chemical depth profiling of the oxide-semiconductor interface via hard x-ray photoemission spectroscopy, we show how to systematically minimize both Eu silicide and Si oxide formation to the sub-monolayer regime-and how to ultimately interface-engineer chemically clean, heteroepitaxial and ferromagnetic EuO/Si (001) in order to create a strong spin filter contact to silicon. PMID:26975515

  17. Interface Engineering to Create a Strong Spin Filter Contact to Silicon

    NASA Astrophysics Data System (ADS)

    Caspers, C.; Gloskovskii, A.; Gorgoi, M.; Besson, C.; Luysberg, M.; Rushchanskii, K. Z.; Ležaić, M.; Fadley, C. S.; Drube, W.; Müller, M.

    2016-03-01

    Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on silicon is a perfect route to enrich silicon nanotechnology with spin filter functionality. To date, the inherent chemical reactivity between EuO and Si has prevented a heteroepitaxial integration without significant contaminations of the interface with Eu silicides and Si oxides. We present a solution to this long-standing problem by applying two complementary passivation techniques for the reactive EuO/Si interface: (i) an in situ hydrogen-Si (001) passivation and (ii) the application of oxygen-protective Eu monolayers–without using any additional buffer layers. By careful chemical depth profiling of the oxide-semiconductor interface via hard x-ray photoemission spectroscopy, we show how to systematically minimize both Eu silicide and Si oxide formation to the sub-monolayer regime–and how to ultimately interface-engineer chemically clean, heteroepitaxial and ferromagnetic EuO/Si (001) in order to create a strong spin filter contact to silicon.

  18. Interface Engineering to Create a Strong Spin Filter Contact to Silicon

    PubMed Central

    Caspers, C.; Gloskovskii, A.; Gorgoi, M.; Besson, C.; Luysberg, M.; Rushchanskii, K. Z.; Ležaić, M.; Fadley, C. S.; Drube, W.; Müller, M.

    2016-01-01

    Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on silicon is a perfect route to enrich silicon nanotechnology with spin filter functionality. To date, the inherent chemical reactivity between EuO and Si has prevented a heteroepitaxial integration without significant contaminations of the interface with Eu silicides and Si oxides. We present a solution to this long-standing problem by applying two complementary passivation techniques for the reactive EuO/Si interface: (i) an in situ hydrogen-Si (001) passivation and (ii) the application of oxygen-protective Eu monolayers–without using any additional buffer layers. By careful chemical depth profiling of the oxide-semiconductor interface via hard x-ray photoemission spectroscopy, we show how to systematically minimize both Eu silicide and Si oxide formation to the sub-monolayer regime–and how to ultimately interface-engineer chemically clean, heteroepitaxial and ferromagnetic EuO/Si (001) in order to create a strong spin filter contact to silicon. PMID:26975515

  19. sup 3 He and methane in the Gulf of Aden

    SciTech Connect

    Jean-Baptiste, P.; Alaux, G. ); Belviso, S.; Nguyen, B.C.; Mihalopoulos, N. )

    1990-01-01

    During the OCEAT cruise (July, 1987), the vertical and spatial distributions of {sup 3}He and methane were measured at six stations over the West Sheba Ridge (Gulf of Aden). The results show significant {delta}{sup 3}He anomalies (up to 49%). The authors conclude that the origin of this signal is independent from the well known Red Sea hydrothermal {sup 3}He (of the Red Sea Brines). Thus, active hydrothermalism occurs in this extensional basin associated with spreading along an incipient mid-ocean ridge. The {sup 3}He input from the Gulf of Aden accounts for the S-N positive gradient in {sup 3}He concentration observed in the western part of the Indian Ocean. Several methane anomalies are also present (up to 664 nl/l,i.e., 25 times the regional methane background), but the CH{sub 4} and {sup 3}He signals are not systematically correlated, suggesting complex production and consumption mechanisms of methane in these areas. The authors results confirm previous observations in the South West Pacific Ocean.

  20. Measuring Glass Thickness of a Reference Cell Used in a Polarized 3HE Experiment

    SciTech Connect

    Justis, N.; Chen, J.

    2005-01-01

    Studies of the spin structure of the neutron are often conducted using a polarized 3He target due to its close spin resemblance to that of a free neutron. Experiments are conducted by bombarding polarized 3He nuclei with high-energy electrons from a linear accelerator. The polarized 3He gas is contained in a glass tube-like cell called the target cell. In addition to the target cell, a reference cell is also used for calibration purposes. The thickness of each cell must be accurately determined for the analysis of the scattering data of the experiment. The thickness of a reference cell was determined by using a tunable infrared laser to create a thin-film interference pattern by reflecting the laser light off of the glass cell. The intensity of the pattern is known to vary sinusoidally as the wavelength of the laser changes. Such variation was recorded as an array of numbers by a LabView program at 26 different points on the cell. Each of the 26 sets of data were fit to an equation containing the thickness variable to determine the thickness of the glass. The cell side, or wall, thickness ranged from 1.42 mm to 1.65 mm, with an uncertainty of less than 5% in every case. End, or window, thickness measurements were also successfully taken, but have yet to be fitted to the derived equation.

  1. Precision neutron interferometric measurement of the n- 3He coherent neutron scattering length

    NASA Astrophysics Data System (ADS)

    Huffman, P. R.; Jacobson, D. L.; Schoen, K.; Arif, M.; Black, T. C.; Snow, W. M.; Werner, S. A.

    2004-07-01

    A measurement of the n- 3He coherent scattering length using neutron interferometry is reported. The result, bc =(5.8572±0.0072) fm , improves the measured precision of any single measurement of bc by a factor of eight; the previous world average, bc =(5.74±0.04) fm , now becomes bc =(5.853±0.007) fm . Measurements of the n-p , n-d , and n- 3He coherent scattering lengths have now been performed using the same technique, thus allowing one to extract the scattering length ratios: parameters that minimize systematic errors. We obtain values of bn 3He / bnp =(-1.5668±0.0021) and bnd / bnp =(-1.7828±0.0014) . Using the new world average value of bc and recent high-precision spin-dependent scattering length data also determined by neutron optical techniques, we extract new values for the bound singlet and triple scattering lengths of b0 =(9.949±0.027) fm and b1 =(4.488±0.017) fm for the n- 3He system. The free nuclear singlet and triplet scattering lengths are a0 =(7.456±0.020) fm and a1 =(3.363±0.013) fm . The coherent scattering cross section is σc =(4.305±0.007) b and the total scattering cross section is σs =(5.837±0.014) b . Comparisons of a0 and a1 to the only existing high-precision theoretical predictions for the n- 3He system, calculated using a resonating group technique with nucleon-nucleon potentials incorporating three-nucleon forces, have been performed. Neutron scattering length measurements in few-body systems are now sensitive enough to probe small effects not yet adequately treated in present theoretical models.

  2. The First Measurement of Neutron Transversity on a Transversely Polarized 3He Target

    SciTech Connect

    Yi Qiang

    2009-12-01

    We recently measured the neutron target single spin asymmetry in the semi-inclusive deep inelastic 3He (e,e',pi+/-)X reactions with a transversely polarized 3He target. The experiment was performed in Hall A at Jefferson Lab from October 2008 to February 2009. Pions were detected in the high-resolution spectrometer in coincidence with scattered electrons detected by the BigBite spectrometer. The kinematic coverage focuses on the valence quark region, x = 0.1 - 0.4, at Q2 = 1-3 (GeV/c)2. With good particle identifications using a RICH detector and an aerogel Cherenkov counter, data on kaons were obtained at the same time. The data from this experiment, when combined with the world data, will provide constraints on the Transversity and Sivers distributions on both u-quark and d-quark in the valence quark region.

  3. Signatures of Majorana and Weyl Fermions in confined phases of superfluid 3He

    NASA Astrophysics Data System (ADS)

    Sauls, James

    2015-03-01

    The B-phase of superfluid 3He exhibits symmetry breaking in which separate invariance under gauge-, spin- and orbital rotations is reduced to the maximal sub-group, SO(3) L + S × T . Parity is broken, but time-reversal is preserved. Broken relative spin-orbit rotational symmetry implies emergent spin-orbit coupling and non-trivial topology of the ground state, both of which are encoded in the Bogoliubov-Nambu Hamiltonian: calH = ξ (p) τ3 + c p . σ -->τ1 , where c = Δ /pf is several orders of magnitude slower than the Fermi velocity. The topology of the B-phase is expressed in terms of a non-trivial winding number for the mapping between momentum space and Nambu space, N3D = ∫d3/p 24π2 ɛijkTr T C (calH - 1∂pi calH) × (calH - 1∂pj calH) (calH - 1∂pk calH) = 2 , where C is the particle-hole transformation. The physical consequence of N3D ≠ 0 is the emergence of a spectrum of Majorana fermions confined on any surface of 3He-B whose effective Hamiltonian is described H =∑p| |Ψ-p|| Tp| | × σ --> . s& circ;Ψp| | . The surface excitations are self-conjugate Majorana fermions with a gapless relativistic dispersion relation ɛ (p) = c | p| | | , and their spins locked normal to the in-plane momentum and the surface normal, s& circ;. In this talk I describe theoretical predictions for experimental signatures based on NMR, mass flow, local ion probes and ultra-sound spectroscopy of these unique quanta that reflect the topological nature of the ground state of superfluid 3He. Supported by NSF Grant DMR-1106315.

  4. Perfect spin filtering controlled by an electric field in a bilayer graphene junction: Effect of layer-dependent exchange energy

    NASA Astrophysics Data System (ADS)

    Kitakorn, Jatiyanon; I-Ming, Tang; Bumned, Soodchomshom

    2016-07-01

    Magneto transport of carriers with a spin-dependent gap in a ferromagnetic-gated bilayer of graphene is investigated. We focus on the effect of an energy gap induced by the mismatch of the exchange fields in the top and bottom layers of an AB-stacked graphene bilayer. The interplay of the electric and exchange fields causes the electron to acquire a spin-dependent energy gap. We find that, only in the case of the anti-parallel configuration, the effect of a magnetic-induced gap will give rise to perfect spin filtering controlled by the electric field. The resolution of the spin filter may be enhanced by varying the bias voltage. Perfect switching of the spin polarization from + 100% to ‑100% by reversing the direction of electric field is predicted. Giant magnetoresistance is predicted to be easily realized when the applied electric field is smaller than the magnetic energy gap. It should be pointed out that the perfect spin filter is due to the layer-dependent exchange energy. This work points to the potential application of bilayer graphene in spintronics. Project supported by the Kasetsart University Research and Development Institute (KURDI) and Thailand Research Fund (TRF) (Grant No. TRG5780274).

  5. Final state interaction in (3He, 2He) reactions

    NASA Astrophysics Data System (ADS)

    Congedo, T. V.; Lee-Fan, I. S.; Cohen, B. L.

    1980-09-01

    The two protons from 2He breakup following (3He, 2He) reactions were detected in coincidence, and energy and angular correlations between them were studied and compared with predictions of the final state interaction theories of Watson and Migdal and Phillips, Griffy, and Biedenharn. The angular correlation between the breakup protons drops off much faster than predicted by these theories; a final state interaction empirically derived to fit the angular correlation is sharply peaked at a breakup energy ~ 0.6 MeV and is quite narrow. Energy distributions of the protons have a dip at the center for small correlation angles which disappears at larger angles. This is well predicted by all final state interaction theories but the slopes of these distributions are much better fit by the empirical final state interaction than by Watson and Migdal or by Phillips, Griffy, and Biedenharn. By maintaining a constant small correlation angle (proton detectors close together), 2He angular distributions were measured and found to be in good agreement with distorted-wave Born approximation predictions. NUCLEAR REACTIONS 64Ni(3He, 2p), E=13 MeV; measured σ(θ), pp correlation; deduced pp FSI; calculated 2He detection efficiency. 9Be(3He, 2p), E=13 MeV; measured σ(θ). 27Al, 90Zr(3He, 2p) measured pp correlation. 51V, 65Cu, 89Y(3He, 2p), E=13 MeV, 17 MeV, measured σ(θ), DWBA analysis.

  6. Dynamics of vortex nucleation in sup 3 He- A flow

    SciTech Connect

    Kopnin, N.B.; Soininen, P.I.; Salomaa, M.M. )

    1992-03-01

    Quantum phase slippage in superfluid {sup 3}He flow is simulated numerically in rectangular slab geometries. Assuming that the flow is confined to a channel having horizontal surfaces close to each other, the spatial problem reduces to the two transverse dimensions; we report time-dependent computer simulations of superfluid {sup 3}He flow in 2+1 dimensions using the time-dependent Ginzburg-Landau equations. The quantum-dynamic processes of phase slippage in {sup 3}He are demonstrated to be associated with superfluid vortex nucleation; we thus confirm Anderson's assumption for phase slippage through vortex motion in superfluids. We also find several other phase-slip scenarios involving vortices, phase-slip lines, and combinations thereof for the coupled multicomponent order-parameter amplitudes. We consider both diffuse and specular boundary conditions at the side walls and demonstrate that our results are essentially independent of the boundaries. We compute the critical current for vortex nucleation as a function of the channel width, and compare it with existing theories of vortex nucleation; we also discuss our calculations in connection with experiments on phase slippage in {sup 3}He flow. One of our most important results is that the superfluid order parameter for the vortices generated in the computer simulations does not vanish anywhere; i.e., the vortices possess superfluid core structures; hence the processes of phase slip for superfluid {sup 3}He are nonlocal in space-time.

  7. Solar source regions of 3HE-rich particle events

    NASA Technical Reports Server (NTRS)

    Reames, D. V.; Stone, R. G.; Kahler, S. W.; Lin, R. P.; Liggett, M.

    1985-01-01

    Hydrogen alpha X-ray, and metric and kilometric radio data to examine the solar sources of energetic 3He-rich particle events observed near earth in association with impulsive 2 to 100 keV electron events were applied. Each 3He/electron event is associated with a kilometric type 3 burst belonging to a family of such bursts characterized by similar interplanetary propagation paths from the same solar active region. The 3He/electron events correlate very well with the interplanetary low frequency radio brightnesses of these events, but progressively worse with signatures from regions closer to the Sun. When H alpha brightnings can be associated with 3He/electron events, they have onsets coinciding to within 1 min of that of the associated metric type 3 burst but are often too small to be reported. The data are consistent with the earlier idea that many type 3 bursts, the 3He/electron events, are due to particle acceleration in the corona, well above the associated H alpha and X-ray flares.

  8. Strong-Coupling and the Stripe Phase of ^3He

    NASA Astrophysics Data System (ADS)

    Wiman, Joshua J.; Sauls, J. A.

    2016-09-01

    Thin films of superfluid 3He were predicted, based on weak-coupling BCS theory, to have a stable phase which spontaneously breaks translational symmetry in the plane of the film. This crystalline superfluid, or "stripe" phase, develops as a one-dimensional periodic array of domain walls separating degenerate B phase domains. We report calculations of the phases and phase diagram for superfluid 3He in thin films using a strong-coupling Ginzburg-Landau theory that accurately reproduces the bulk 3He superfluid phase diagram. We find that the stability of the Stripe phase is diminished relative to the A phase, but the Stripe phase is stable in a large range of temperatures, pressures, confinement, and surface conditions.

  9. Nuclear electric dipole moment of {sup 3}He

    SciTech Connect

    Stetcu, I.; Friar, J. L.; Hayes, A. C.; Liu, C.-P.; Navratil, P.

    2009-01-28

    In the no-core shell model (NCSM) framework, we calculate the {sup 3}He electric dipole moment (EDM) generated by parity- and time-reversal violation in the nucleon-nucleon interaction. While the results are somehow sensitive to the interaction model chosen for the strong two- and three-body interactions, we demonstrate the pion-exchange dominance to the EDM of {sup 3}He, if the coupling constants for {pi}, {rho} and {omega}-exchanges are of comparable magnitude, as expected. Finally, our results suggest that a measurement of {sup 3}He EDM would be complementary to the currently planned neutron and deuteron experiments, and would constitute a powerful constraint to the models of the pion P- and T-violating interactions.

  10. Surface Waves on the Superfluids ^3He and ^4He

    NASA Astrophysics Data System (ADS)

    Manninen, M. S.; Ranni, A.; Rysti, J.; Todoshchenko, I. A.; Tuoriniemi, J. T.

    2016-06-01

    Free surface waves were examined both in superfluids ^3He and ^4He with the premise that these inviscid media would represent ideal realizations for this fluid dynamics problem. The work in ^3He is one of the first of its kind, but in ^4He, it was possible to produce a much more complete set of data for meaningful comparison with theoretical models. Most measurements were performed at the zero temperature limit, meaning T< 100 mK for ^4He and T˜ 100 μ K for ^3He. Dozens of surface wave resonances, including up to 11 overtones, were observed and monitored as the liquid depth in the cell was varied. Despite of the wealth of data, perfect agreement with the constructed theoretical models could not be achieved.

  11. Surface Waves on the Superfluids ^3 He and ^4 He

    NASA Astrophysics Data System (ADS)

    Manninen, M. S.; Ranni, A.; Rysti, J.; Todoshchenko, I. A.; Tuoriniemi, J. T.

    2016-04-01

    Free surface waves were examined both in superfluids ^3 He and ^4 He with the premise that these inviscid media would represent ideal realizations for this fluid dynamics problem. The work in ^3 He is one of the first of its kind, but in ^4 He, it was possible to produce a much more complete set of data for meaningful comparison with theoretical models. Most measurements were performed at the zero temperature limit, meaning T< 100 mK for ^4 He and T˜ 100 μ K for ^3 He. Dozens of surface wave resonances, including up to 11 overtones, were observed and monitored as the liquid depth in the cell was varied. Despite of the wealth of data, perfect agreement with the constructed theoretical models could not be achieved.

  12. Coherent photoproduction of {pi}{sup +} from {sup 3}He

    SciTech Connect

    Nasseripour, R.; Berman, B.L.; Briscoe, W.J.; Micherdzinska, A.M.; Munevar, E.; Adhikari, K.P.; Adikaram, D.; Hyde, C.E.; Klein, A.; Kuhn, S.E.; Mayer, M.; Seraydaryan, H.; Weinstein, L.B.; Anghinolfi, M.; Battaglieri, M.; De Vita, R.; Osipenko, M.; Ripani, M.; Ball, J.; Konczykowski, P.

    2011-03-15

    We have measured the differential cross section for the {gamma}{sup 3}He{yields}{pi}{sup +}t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid {sup 3}He target. The differential cross sections for the {gamma}{sup 3}He{yields}{pi}{sup +}t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model.

  13. Resonant TMR inversion in LiF/EuS based spin-filter tunnel junctions

    NASA Astrophysics Data System (ADS)

    Liu, Fen; Yang, Yihang; Xue, Qian; Gao, Zhiwei; Chen, Aixi; Miao, Guo-Xing

    2016-08-01

    Resonant tunneling can lead to inverse tunnel magnetoresistance when impurity levels rather than direct tunneling dominate the transport process. We fabricated hybrid magnetic tunnel junctions of CoFe/LiF/EuS/Ti, with an epitaxial LiF energy barrier joined with a polycrystalline EuS spin-filter barrier. Due to the water solubility of LiF, the devices were fully packaged in situ. The devices showed sizeable positive TMR up to 16% at low bias voltages but clearly inverted TMR at higher bias voltages. The TMR inversion depends sensitively on the thickness of LiF, and the tendency of inversion disappears when LiF gets thick enough and recovers its intrinsic properties.

  14. A structurally-controllable spin filter in a δ-doped magnetically modulated semiconductor nanostructure with zero average magnetic field

    NASA Astrophysics Data System (ADS)

    Shen, Li-Hua; Ma, Wen-Yue; Zhang, Gui-Lian; Yang, Shi-Peng

    2015-07-01

    We report on a theoretical investigation of spin-polarized transport in a δ-doped magnetically modulated semiconductor nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe on the top of a semiconductor heterostructure and by using the atomic layer doping technique such as molecular beam epitaxy (MBE). It is shown that although such a nanostructure has a zero average magnetic filed, a sizable spin polarization exists due to the Zeeman splitting mechanism. It is also shown that the degree of spin polarization varies sensitively with the weight and/or position of the δ-doping. Therefore, one can conveniently tailor the behaviour of the spin-polarized electron by tuning the δ -doping, and such a device can be employed as a controllable spin filter for spintronics.

  15. Anisotropic phases of superfluid ^{3}he in compressed aerogel.

    PubMed

    Li, J I A; Zimmerman, A M; Pollanen, J; Collett, C A; Halperin, W P

    2015-03-13

    It has been shown that the relative stabilities of various superfluid states of ^{3}He can be influenced by anisotropy in a silica aerogel framework. We prepared a suite of aerogel samples compressed up to 30% for which we performed pulsed NMR on ^{3}He imbibed within the aerogel. We identified A and B phases and determined their magnetic field-temperature phase diagrams as a function of strain. From these results, we infer that the B phase is distorted by negative strain forming an anisotropic superfluid state more stable than the A phase. PMID:25815941

  16. A Study of 3He detectors for Active Interrogation

    SciTech Connect

    E.H. Seabury; D.L. Chichester

    2009-10-01

    3He proportional counters have long been used as neutron detectors for both passive and active detection of Special Nuclear Material (SNM). The optimal configuration of these detectors as far as gas pressure, amount of moderating material, and size are concerned is highly dependent on what neutron signatures are being used to detect and identify SNM. We present here a parametric study of the neutron capture response of 3He detectors, based on Monte Carlo simulations using the MCNPX radiation transport code. The neutron capture response of the detectors has been modeled as a function of time after an incident neutron pulse.

  17. Rotational quenching of CS in ultracold 3He collisions

    NASA Astrophysics Data System (ADS)

    Kaur, Rajwant; Dhilip Kumar, T. J.

    2016-08-01

    Quantum mechanical scattering calculations of rotational quenching of CS (v = 0) collision with 3He are performed at ultracold temperatures and results are compared with isotopic 4He collision. Rotational quenching cross sections and rate coefficients have been calculated in the ultracold region for rotational levels up to j = 10 using the He-CS potential energy surface computed at the CCSD(T)/aug-cc-pVQZ level of theory. The quenching cross sections are found to be two orders of magnitude larger for the 3He than the 4He isotope under ultracold conditions. Wigner threshold law is found to be valid below 10-3 K temperature.

  18. Chiral molecule for spin filtering purposes: the study of L- and D-Alanine

    NASA Astrophysics Data System (ADS)

    Yitamben, Esmeralda; Rosenberg, Richard; Guisinger, Nathan

    2011-03-01

    The field of molecular electronics has attracted scientists by the great opportunities and versatility it offers as a replacement for standard semiconductor electronics with organic materials, thus bringing down the cost, and opening endless possibilities for chemical synthesis, and scientific breakthrough. Of particular interest is the use of chiral molecules, such as alanine, for spin filtering studies in hope of creating highly spin-polarized charge carriers for spintronics applications. Preliminary studies of both L- and D-alanine on Cu(111) were conducted using scanning tunneling microscopy and spectroscopy, revealing the formation of a 2-dimensional phase at low coverage, a hexagonal ``flower'' pattern at intermediate coverage, and a chain and ring superstructures at high coverage. A model is proposed to explain the surface chemistry and bonding of the molecules on the metallic surface. Current studies of L- and D-alanine on Fe/W show promises in the intermediate coverage regime. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  19. High-volume 100 Liter-per-day SEOP Polarization of 3He

    NASA Astrophysics Data System (ADS)

    Hersman, William; Watt, David W.; Ruset, Iulian C.; Distelbrink, Jan H.; Ketel, Jeff

    We describe a novel apparatus for large-scale production of polarized 3He using Spin-Exchange Optical Pumping (SEOP). The large optical pumping cell is enclosed inside a pressure containment vessel to equalize the differential pressure across the glass cell walls. Numerical simulations of laser absorption and spin-transfer guided our choice of pressure, temperature, and laser power. Computational fluid dynamics simulations of the two-zone thermal bath environment revealed buoyancy-induced flow which favored operation inclined at an angle. We prepared and tested three separate 8.5 liter cells at internal pressures up to six amagat (50 bar-liters) with hybrid alkali ratios of K:Rb of 10:1 by mass (4.4:1 by number ratio) and at temperatures up to 250°C. An early prototype used a 1.4 kW broadband laser, while our most recent prototype incorporated a new 2.2kW spectrally narrowed external cavity laser. Using small surface coil NMR to measure polarization, we obtained spin-up rates greater than 20% per hour consistent with our numerical simulations. Unfortunately, each cell installation to date has been compromised, limiting T1 relaxation times to 12 hours and asymptotic polarizations to values below 50%. If a cell could be installed with 50 hour lifetime and X-factor of 0.2, this polarizer will deliver 50 liters of over 70% polarized 3He twice each day.

  20. Minimal mass size of a stable {sup 3}He cluster

    SciTech Connect

    Guardiola, R.; Navarro, J.

    2005-03-01

    The minimal number of {sup 3}He atoms required to form a bound cluster has been estimated by means of a diffusion Monte Carlo procedure within the fixed-node approximation. Several importance sampling wave functions have been employed in order to consider different shell-model configurations. The resulting upper bound for the minimal number is 32 atoms.

  1. Probing lung microstructure with hyperpolarized 3He gradient echo MRI.

    PubMed

    Sukstanskii, Alexander L; Quirk, James D; Yablonskiy, Dmitriy A

    2014-12-01

    In this paper we demonstrate that gradient echo MRI with hyperpolarized (3)He gas can be used for simultaneously extracting in vivo information about lung ventilation properties, alveolar geometrical parameters, and blood vessel network structure. This new approach is based on multi-gradient-echo experimental measurements of hyperpolarized (3)He gas MRI signal from human lungs and a proposed theoretical model of this signal. Based on computer simulations of (3)He atoms diffusing in the acinar airway tree in the presence of an inhomogeneous magnetic field induced by the susceptibility differences between lung tissue (alveolar septa, blood vessels) and lung airspaces, we derive analytical expressions relating the time-dependent MR signal to the geometrical parameters of acinar airways and the blood vessel network. Data obtained on eight healthy volunteers are in good agreement with literature values. This information is complementary to the information obtained by means of the in vivo lung morphometry technique with hyperpolarized 3He diffusion MRI previously developed by our group, and opens new opportunities to study lung microstructure in health and disease. PMID:24920182

  2. Acoustic Spectroscopy of Superfluid 3He in Aerogel

    SciTech Connect

    Davis, J. P.; Choi, H.; Pollanen, J.; Halperin, W. P.

    2006-09-07

    We have designed an experiment to study the role of global anisotropic quasiparticle scattering on the dirty aerogel superfluid 3He system. We observe significant regions of two stable phases at temperatures below the superfluid transition at a pressure of 25 bar for a 98% aerogel.

  3. Flight performance of a rocket-borne 3He refrigerator

    NASA Astrophysics Data System (ADS)

    Duband, L.; Alsop, D.; Lange, A.; Hayata, S.; Matsumoto, T.; Sato, S.

    A self-contained, recyclable 3He refrigerator suitable for use in zero-gravity has been developed. This refrigerator successfully flew on 5 September 1989, as part of an S-520 sounding rocket payload designed to measure the spectrum of the cosmic submillimetre background. This paper presents the cryogenic performance of the refrigerator during flight.

  4. Coexistence of perfect spin filtering for entangled electron pairs and high magnetic storage efficiency in one setup.

    PubMed

    Ji, T T; Bu, N; Chen, F J; Tao, Y C; Wang, J

    2016-01-01

    For Entangled electron pairs superconducting spintronics, there exist two drawbacks in existing proposals of generating entangled electron pairs. One is that the two kinds of different spin entangled electron pairs mix with each other. And the other is a low efficiency of entanglement production. Herein, we report the spin entanglement state of the ferromagnetic insulator (FI)/s-wave superconductor/FI structure on a narrow quantum spin Hall insulator strip. It is shown that not only the high production of entangled electron pairs in wider energy range, but also the perfect spin filtering of entangled electron pairs in the context of no highly spin-polarized electrons, can be obtained. Moreover, the currents for the left and right leads in the antiferromagnetic alignment both can be zero, indicating 100% tunnelling magnetoresistance with highly magnetic storage efficiency. Therefore, the spin filtering for entangled electron pairs and magnetic storage with high efficiencies coexist in one setup. The results may be experimentally demonstrated by measuring the tunnelling conductance and the noise power. PMID:27074893

  5. Coexistence of perfect spin filtering for entangled electron pairs and high magnetic storage efficiency in one setup

    NASA Astrophysics Data System (ADS)

    Ji, T. T.; Bu, N.; Chen, F. J.; Tao, Y. C.; Wang, J.

    2016-04-01

    For Entangled electron pairs superconducting spintronics, there exist two drawbacks in existing proposals of generating entangled electron pairs. One is that the two kinds of different spin entangled electron pairs mix with each other. And the other is a low efficiency of entanglement production. Herein, we report the spin entanglement state of the ferromagnetic insulator (FI)/s-wave superconductor/FI structure on a narrow quantum spin Hall insulator strip. It is shown that not only the high production of entangled electron pairs in wider energy range, but also the perfect spin filtering of entangled electron pairs in the context of no highly spin-polarized electrons, can be obtained. Moreover, the currents for the left and right leads in the antiferromagnetic alignment both can be zero, indicating 100% tunnelling magnetoresistance with highly magnetic storage efficiency. Therefore, the spin filtering for entangled electron pairs and magnetic storage with high efficiencies coexist in one setup. The results may be experimentally demonstrated by measuring the tunnelling conductance and the noise power.

  6. Coexistence of perfect spin filtering for entangled electron pairs and high magnetic storage efficiency in one setup

    PubMed Central

    Ji, T. T.; Bu, N.; Chen, F. J.; Tao, Y. C.; Wang, J.

    2016-01-01

    For Entangled electron pairs superconducting spintronics, there exist two drawbacks in existing proposals of generating entangled electron pairs. One is that the two kinds of different spin entangled electron pairs mix with each other. And the other is a low efficiency of entanglement production. Herein, we report the spin entanglement state of the ferromagnetic insulator (FI)/s-wave superconductor/FI structure on a narrow quantum spin Hall insulator strip. It is shown that not only the high production of entangled electron pairs in wider energy range, but also the perfect spin filtering of entangled electron pairs in the context of no highly spin-polarized electrons, can be obtained. Moreover, the currents for the left and right leads in the antiferromagnetic alignment both can be zero, indicating 100% tunnelling magnetoresistance with highly magnetic storage efficiency. Therefore, the spin filtering for entangled electron pairs and magnetic storage with high efficiencies coexist in one setup. The results may be experimentally demonstrated by measuring the tunnelling conductance and the noise power. PMID:27074893

  7. A 3 He-129 Xe co-magnetometer with 87 Rb magnetometry

    NASA Astrophysics Data System (ADS)

    Limes, Mark; Sheng, Dong; Romalis, Mike

    2016-05-01

    We report progress on a 3 He-129 Xe co-magnetometer detected with a 87 Rb magnetometer. The noble-gas co-magnetometer is insensitive to any long-term bias field drifts, but the presence of hot Rb can cause instability in the ratio of 3 He-129 Xe precession frequencies. We use a sequence of Rb π pulses to suppress the instability due to Rb-noble gas interactions by a factor of 104 along all three spatial axes. For detection, our 87 Rb magnetometer operates using single-axis 87 Rb π pulses with σ+ /σ- pumping-this technique decouples the 87 Rb magnetometer from bias fields, and allows for SERF operation. We are presently investigating systematic effects due to combinations of several imperfections, such as longitudinal noble gas polarization, imperfect 87 Rb π pulses, and 87 Rb pump light shifts. Thus far, our 87 Rb magnetometer has a sensitivity of 40 fT/√{Hz}, and our 3 He-129 Xe co-magnetometer has achieved a single-shot precession frequency ratio error of 20 nHz and a long-term bias drift of 8 nHz at 7 h. We are developing the co-magnetometer for use as an NMR gyro, and to search for possible spin-gravity interactions. Supported by DARPA and NSF.

  8. JET (3He)-D scenarios relying on RF heating: survey of selected recent experiments

    NASA Astrophysics Data System (ADS)

    Van Eester, D.; Lerche, E.; Andrew, Y.; Biewer, T. M.; Casati, A.; Crombé, K.; de la Luna, E.; Ericsson, G.; Felton, R.; Giacomelli, L.; Giroud, C.; Hawkes, N.; Hellesen, C.; Hjalmarsson, A.; Joffrin, E.; Källne, J.; Kiptily, V.; Lomas, P.; Mantica, P.; Marinoni, A.; Mayoral, M.-L.; Ongena, J.; Puiatti, M.-E.; Santala, M.; Sharapov, S.; Valisa, M.; JET EFDA contributors

    2009-04-01

    Recent JET experiments have been devoted to the study of (3He)-D plasmas involving radio frequency (RF) heating. This paper starts by discussing the RF heating efficiency theoretically expected in such plasmas, covering both relevant aspects of wave and of particle dynamics. Then it gives a concise summary of the main conclusions drawn from recent experiments that were either focusing on studying RF heating physics aspects or that were adopting RF heating as a tool to study plasma behavior. Depending on the minority concentration chosen, different physical phenomena are observed. At very low concentration (X[3He] < 1%), energetic tails are formed which trigger MHD activity and result in loss of fast particles. Alfvén cascades were observed and gamma ray tomography indirectly shows the impact of sawtooth crashes on the fast particle orbits. Low concentration (X[3He] < 10%) favors minority heating while for X[3He] Gt 10% electron mode conversion damping becomes dominant. Evidence for the Fuchs et al standing wave effect (Fuchs et al 1995 Phys. Plasmas 2 1637-47) on the absorption is presented. RF induced deuterium tails were observed in mode conversion experiments with large X[3He] (≈18%). As tentative modeling shows, the formation of these tails can be explained as a consequence of wave power absorption by neutral beam particles that efficiently interact with the waves well away from the cold D cyclotron resonance position as a result of their substantial Doppler shift. As both ion and electron RF power deposition profiles in (3He)-D plasmas are fairly narrow—giving rise to localized heat sources—the RF heating method is an ideal tool for performing transport studies. Various of the experiments discussed here were done in plasmas with internal transport barriers (ITBs). ITBs are identified as regions with locally reduced diffusivity, where poloidal spinning up of the plasma is observed. The present know-how on the role of RF heating for impurity transport is

  9. Spin-filtering effect in the transport through a single-molecule magnet Mn12 bridged between metallic electrodes

    NASA Astrophysics Data System (ADS)

    Barraza-Lopez, Salvador; Park, Kyungwha; García-Suárez, Víctor; Ferrer, Jaime

    2009-04-01

    Electronic transport through a single-molecule magnet Mn12 in a two-terminal setup is calculated using the nonequilibrium Green's function method in conjunction with density-functional theory. A single-molecule magnet Mn12 is bridged between Au(111) electrodes via thiol group and alkane chains such that its magnetic easy axis is normal to the transport direction. A computed spin-polarized transmission coefficient in zero bias reveals that resonant tunneling near the Fermi level occurs through some molecular orbitals of majority spin only. Thus, for low bias voltages, a spin-filtering effect such as only one spin component contributing to the conductance is expected. This effect would persist even with inclusion of additional electron correlations.

  10. Measurement of "pretzelosity" asymmetry of charged pion production in semi-inclusive deep inelastic scattering on a polarized 3He target

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Qian, X.; Allada, K.; Dutta, C.; Huang, J.; Katich, J.; Wang, Y.; Aniol, K.; Annand, J. R. M.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Bradshaw, P. C.; Bosted, P.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J.-P.; Chen, W.; Chirapatpimol, K.; Chudakov, E.; Cisbani, E.; Cornejo, J. C.; Cusanno, F.; Dalton, M. M.; Deconinck, W.; de Jager, C. W.; De Leo, R.; Deng, X.; Deur, A.; Ding, H.; Dolph, P. A. M.; Dutta, D.; El Fassi, L.; Frullani, S.; Gao, H.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Guo, L.; Hamilton, D.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, M.; Ibrahim, H. F.; Iodice, M.; Jiang, X.; Jin, G.; Jones, M. K.; Kelleher, A.; Kim, W.; Kolarkar, A.; Korsch, W.; LeRose, J. J.; Li, X.; Li, Y.; Lindgren, R.; Liyanage, N.; Long, E.; Lu, H.-J.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; McNulty, D.; Meziani, Z.-E.; Michaels, R.; Moffit, B.; Muñoz Camacho, C.; Nanda, S.; Narayan, A.; Nelyubin, V.; Norum, B.; Oh, Y.; Osipenko, M.; Parno, D.; Peng, J. C.; Phillips, S. K.; Posik, M.; Puckett, A. J. R.; Qiang, Y.; Rakhman, A.; Ransome, R. D.; Riordan, S.; Saha, A.; Sawatzky, B.; Schulte, E.; Shahinyan, A.; Shabestari, M. H.; Širca, S.; Stepanyan, S.; Subedi, R.; Sulkosky, V.; Tang, L.-G.; Tobias, W. A.; Urciuoli, G. M.; Vilardi, I.; Wang, K.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Ye, Y.; Ye, Z.; Yuan, L.; Zhan, X.; Zhang, Y.-W.; Zhao, B.; Zheng, X.; Zhu, L.; Zhu, X.; Zong, X.; Jefferson Lab Hall A Collaboration

    2014-11-01

    An experiment to measure single-spin asymmetries of semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized 3He target was performed at Jefferson Laboratory in the kinematic region of 0.16 3He, which are expressed as the convolution of the h1T ⊥ transverse-momentum-dependent distribution functions and the Collins fragmentation functions in the leading order, were measured for the first time. Under the effective polarization approximation, we extracted the corresponding neutron asymmetries from the measured 3He asymmetries and cross-section ratios between the proton and 3He. Our results show that both π± on 3He and on neutron pretzelosity asymmetries are consistent with zero within experimental uncertainties.

  11. Surface half-metallicity of CrS thin films and perfect spin filtering and spin diode effects of CrS/ZnSe heterostructure

    SciTech Connect

    Gao, G. Y. Yao, K. L.

    2014-11-03

    Recently, ferromagnetic zinc-blende Mn{sub 1−x}Cr{sub x}S thin films (above x = 0.5) were fabricated experimentally on ZnSe substrate, which confirmed the previous theoretical prediction of half-metallic ferromagnetism in zinc-blende CrS. Here, we theoretically reveal that both Cr- and S-terminated (001) surfaces of the CrS thin films retain the half-metallicity. The CrS/ZnSe(001) heterogeneous junction exhibits excellent spin filtering and spin diode effects, which are explained by the calculated band structure and transmission spectra. The perfect spin transport properties indicate the potential applications of half-metallic CrS in spintronic devices. All computational results are obtained by using the density functional theory combined with nonequilibrium Green's function.

  12. Heat capacity of multilayers of 3He adsorbed on graphite at low millikelvin temperatures

    NASA Astrophysics Data System (ADS)

    Greywall, Dennis S.

    1990-02-01

    Precise heat-capacity results are presented for 3He adsorbed on graphite. The temperature range of the data is from 2 to 200 mK, while the coverages span from somewhat below monolayer completion up through five atomic layers. Promotion of atoms into the second, third, and fourth layers is clearly observed. Nuclear-spin exchange energies of the order of a few tenths of a mK are found for the submonolayer incommensurate solid phase. These values differ significantly from those recently inferred from NMR experiments. Data for the second-layer fluid yield 3He quasiparticle effective masses that agree well with the corresponding first-layer values and range from one to five times the bare 3He mass. Prior to third-layer promotion, the second layer undergoes a first-order phase transition. By comparison with the phase diagram for the first layer, the new phase in the second layer is assumed to be a registered solid. Registry is now with respect to the first 3He layer, which continues to exist as a triangular-lattice solid incommensurate with the graphite substrate. The registered phase exhibits a large, sharp heat-capacity anomaly at 2.5 mK. This anomaly may be due to antiferromagnetic polarons which form around zero-point vacancies or may be the signature of an unusual registered phase in which some of the atoms are positioned at substrate potential maxima. As the coverage is increased further, the second-layer spin peak remains located at 2.5 mK but suddenly grows in amplitude, while the temperature dependence above the peak changes from T-0.5 towards T-2. The anomaly reaches its greatest magnitude at 0.24 atoms/AṦ where, perhaps coincidentally, promotion of atoms into the fourth layer also occurs. At this same coverage previous magnetization measurements have shown a large ferromagnetic peak. The heat-capacity data indicate that the ferromagnetic peak occurs when the second layer exists in a state intermediate between a registered solid and the incommensurate

  13. Heat Capacity of Dilute 3He-4He Monolayer Films

    NASA Astrophysics Data System (ADS)

    Morishita, Masashi

    2016-05-01

    The heat capacities of a small amount of 3He dissolved in monolayer 4He films are measured to clarify natures of monolayer 4He films. With increasing areal density, the measured heat capacities gradually increase and subsequently gradually decrease. With further increase in areal density, the measured heat capacity rapidly decreases to zero over a very narrow areal density range near that of the sqrt{3} × sqrt{3} phase. These slightly complex areal-density variations and dependence on 3He concentration are discussed from the viewpoint of the known properties of 4He films. The behaviors can be explained. However, the expected two-dimensional gas-liquid or gas-solid coexistence is not observed in this study.

  14. Conductance and spin-filter effects of oxygen-incorporated Au, Cu, and Fe single-atom chains

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaolong; Xie, Yi-Qun; Ye, Xiang; Ke, San-Huang

    2015-01-01

    We studied the spin-polarized electron transport in oxygen-incorporated Au, Cu, and Fe single-atom chains (SACs) by first-principles calculations. We first investigated the mechanism responsible for the low conductance (<1G0) of the Au and Cu SACs in an oxygen environment reported in recent experiments. We found that for the Au SACs, the low conductance plateau around 0.6G0 can be attributed to a distorted chain doped with a single oxygen atom, while the 0.1G0 conductance comes from a linear chain incorporated with an oxygen molecule and is caused by an antibonding state formed by oxygen's occupied frontier orbital with dz orbitals of adjacent Au atoms. For the Cu SACs, the conductance about 0.3G0 is ascribed to a special configuration that contains Cu and O atoms in an alternating sequence. This exhibits an even-odd conductance oscillation with an amplitude of ˜0.1G0. In contrast, for the alternating Fe-O SACs, conductance overall decreases with an increase in O atoms and it approaches nearly zero for the chain with more than four O atoms. While the Cu-O SACs behave as perfect spin filters for one spin channel due to the half metallic nature, the Fe-O SACs can serve as perfect spin filters for two spin channels depending on the polarity of the applied gate voltage.

  15. NOVEL CONCEPTS FOR ISOTOPIC SEPARATION OF 3HE/4HE

    SciTech Connect

    Roy, L.; Nigg, H.; Watson, H.

    2012-09-04

    The research outlined below established theoretical proof-of-concept using ab initio calculations that {sup 3}He can be separated from {sup 4}He by taking advantage of weak van der Waals interactions with other higher molecular weight rare gases such as xenon. To the best of our knowledge, this is the only suggested method that exploits the physical differences of the isotopes using a chemical interaction.

  16. Density of liquid 3He in 8 T magnetic field

    NASA Astrophysics Data System (ADS)

    Matsumoto, Koichi; Hasegawa, Syuichi; Okuda, Yuichi

    2000-07-01

    We report a precise measurement of the density of liquid 3He in a 8 T field. Measurements performed at saturated vapour pressure between 30 and 300 mK show a field-induced increase of density. The relative change is about 1×10 -5 in this temperature range. These results are in agreement with a calculation based on a Maxwell relation and the pressure dependence of the susceptibility.

  17. Hard two-body photodisintegration of 3He.

    PubMed

    Pomerantz, I; Ilieva, Y; Gilman, R; Higinbotham, D W; Piasetzky, E; Strauch, S; Adhikari, K P; Aghasyan, M; Allada, K; Amaryan, M J; Anefalos Pereira, S; Anghinolfi, M; Baghdasaryan, H; Ball, J; Baltzell, N A; Battaglieri, M; Batourine, V; Beck, A; Beck, S; Bedlinskiy, I; Berman, B L; Biselli, A S; Boeglin, W; Bono, J; Bookwalter, C; Boiarinov, S; Briscoe, W J; Brooks, W K; Bubis, N; Burkert, V; Camsonne, A; Canan, M; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Chirapatpimol, K; Cisbani, E; Cole, P L; Contalbrigo, M; Crede, V; Cusanno, F; D'Angelo, A; Daniel, A; Dashyan, N; de Jager, C W; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Dutta, C; Egiyan, H; El Alaoui, A; El Fassi, L; Eugenio, P; Fedotov, G; Fegan, S; Fleming, J A; Fradi, A; Garibaldi, F; Geagla, O; Gevorgyan, N; Giovanetti, K L; Girod, F X; Glister, J; Goetz, J T; Gohn, W; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Harrison, N; Heddle, D; Hicks, K; Ho, D; Holtrop, M; Hyde, C E; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jiang, X; Jo, H S; Joo, K; Katramatou, A T; Keller, D; Khandaker, M; Khetarpal, P; Khrosinkova, E; Kim, A; Kim, W; Klein, F J; Koirala, S; Kubarovsky, A; Kubarovsky, V; Kuleshov, S V; Kvaltine, N D; Lee, B; LeRose, J J; Lewis, S; Lindgren, R; Livingston, K; Lu, H Y; MacGregor, I J D; Mao, Y; Martinez, D; Mayer, M; McCullough, E; McKinnon, B; Meekins, D; Meyer, C A; Michaels, R; Mineeva, T; Mirazita, M; Moffit, B; Mokeev, V; Montgomery, R A; Moutarde, H; Munevar, E; Munoz Camacho, C; Nadel-Turonski, P; Nasseripour, R; Nepali, C S; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Pappalardo, L L; Paremuzyan, R; Park, K; Park, S; Petratos, G G; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Procureur, S; Protopopescu, D; Puckett, A J R; Qian, X; Qiang, Y; Ricco, G; Rimal, D; Ripani, M; Ritchie, B G; Rodriguez, I; Ron, G; Rosner, G; Rossi, P; Sabatié, F; Saha, A; Saini, M S; Sarty, A J; Sawatzky, B; Saylor, N A; Schott, D; Schulte, E; Schumacher, R A; Seder, E; Seraydaryan, H; Shneor, R; Smith, G D; Sokhan, D; Sparveris, N; Stepanyan, S S; Stepanyan, S; Stoler, P; Subedi, R; Sulkosky, V; Taiuti, M; Tang, W; Taylor, C E; Tkachenko, S; Ungaro, M; Vernarsky, B; Vineyard, M F; Voskanyan, H; Voutier, E; Walford, N K; Wang, Y; Watts, D P; Weinstein, L B; Weygand, D P; Wojtsekhowski, B; Wood, M H; Yan, X; Yao, H; Zachariou, N; Zhan, X; Zhang, J; Zhao, Z W; Zheng, X; Zonta, I

    2013-06-14

    We have measured cross sections for the γ(3)He → pd reaction at photon energies of 0.4-1.4 GeV and a center-of-mass angle of 90°. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron. PMID:25165915

  18. Light Higgs channel of the resonant decay of magnon condensate in superfluid (3)He-B.

    PubMed

    Zavjalov, V V; Autti, S; Eltsov, V B; Heikkinen, P J; Volovik, G E

    2016-01-01

    In superfluids the order parameter, which describes spontaneous symmetry breaking, is an analogue of the Higgs field in the Standard Model of particle physics. Oscillations of the field amplitude are massive Higgs bosons, while oscillations of the orientation are massless Nambu-Goldstone bosons. The 125 GeV Higgs boson, discovered at Large Hadron Collider, is light compared with electroweak energy scale. Here, we show that such light Higgs exists in superfluid (3)He-B, where one of three Nambu-Goldstone spin-wave modes acquires small mass due to the spin-orbit interaction. Other modes become optical and acoustic magnons. We observe parametric decay of Bose-Einstein condensate of optical magnons to light Higgs modes and decay of optical to acoustic magnons. Formation of a light Higgs from a Nambu-Goldstone mode observed in (3)He-B opens a possibility that such scenario can be realized in other systems, where violation of some hidden symmetry is possible, including the Standard Model. PMID:26743951

  19. Uranium Neutron Coincidence Collar Model Utilizing 3He

    SciTech Connect

    Siciliano, Edward R.; Rogers, Jeremy L.; Schweppe, John E.; Lintereur, Azaree T.; Kouzes, Richard T.

    2012-07-30

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based alternative system in a configuration typically used for 3He-based coincidence counter applications. The specific application selected for boron-lined tube replacement in this project was one of the Uranium Neutron Coincidence Collar (UNCL) designs. This report, providing results for model development of a UNCL, is a deliverable under Task 2 of the project. The current UNCL instruments utilize 3He tubes. As the first step in developing and optimizing a boron-lined proportional counter based version of the UNCL, models of eight different 3He-based UNCL detectors currently in use were developed and evaluated. A comparison was made between the simulated results and measured efficiencies for those systems with values reported in the literature. The reported experimental measurements for efficiencies and die-away times agree to within 10%.

  20. Dating degassed groundwater with 3H/3He

    NASA Astrophysics Data System (ADS)

    Visser, Ate; Broers, Hans Peter; Bierkens, Marc F. P.

    2007-10-01

    The production of gases in groundwater under contaminated locations by geochemical and biological processes is not uncommon. Degassing of these gases from groundwater and repartitioning of noble gases between water and gas phase distorts groundwater dating by 3H/3He. We observed noble gas concentrations below atmospheric equilibrium in 20 out of 34 groundwater samples from agriculturally polluted sandy areas in the Netherlands. From the absence of nitrate in degassed samples, we conclude that denitrification causes degassing. The 22Ne/20Ne ratios show that degassing had attained solubility equilibrium and had not caused isotopic fractionation by diffusion. To correct for the loss of tritiogenic 3He due to degassing, we present a single-step equilibrium degassing model. We use the total dissolved gas pressure at the monitoring screen to estimate the depth and timing of degassing, which is essential to estimate travel times from degassed samples. By propagating the uncertainties in the underlying measurements and assumptions through the travel time calculations, we found a travel time uncertainty of 3 years (a). We therefore conclude that 3H/3He dating can produce valuable information on groundwater flow even at sites with strong degassing.

  1. Second sound experiments in superfluid 3He-A1 phase in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Bastea, Marina

    The Asb1 phase of sp3He is the first observed magnetic superfluid, stable only in the presence of an external magnetic field. Due to the broken relative gauge and spin rotational symmetry, the two associated collective modes, the second sound and the longitudinal spin waves are expected to appear as a single mode which we call the spin-entropy wave. Our work is focused on consistently mapping the behavior of the spin-entropy wave in the superfluid Asb{1} phase of sp3He, under a wide range of experimental conditions. Our results address fundamental questions such as the identification of the order parameter symmetry in the superfluid states, the nature of the pairing state in the Asb1 phase and the superfluid density anisotropy. We extensively investigated the propagation of the spin-entropy wave as a function of temperature, magnetic field between 1 and 8 Tesla and liquid pressure up to 30 bar. Our results show that the superfluid density is directly proportional to the magnitude of the external field in the specified range, as predicted by theory. We discovered that in the vicinity of the transition to the Asb2 phase, over a fairly large temperature range, the spin-entropy wave suffers a divergent attenuation. The observed effects were suggested as evidence for the presence of a minority condensate population, "down spin" pairs, specific for the Asb2 phase, as predicted by Monien and Tewordt. We measured the superfluid density dependence on the pressure between 10 and 30 bar and directly related it to the fourth order coefficients of the Ginzburg-Landau free energy expansion. The pressure dependence of three of these coefficients and their strong coupling corrections was found to be consistent with the theoretical predictions of Sauls and Serene. Our results support the identification of the A phase as the Anderson-Brinkman-Morel axial state and provide an important consistency check for the phase diagram carried out by groups at USC and Cornell. We performed

  2. Site-resolved multiple-quantum filtered correlations and distance measurements by magic-angle spinning NMR: Theory and applications to spins with weak to vanishing quadrupolar couplings.

    PubMed

    Eliav, U; Haimovich, A; Goldbourt, A

    2016-01-14

    We discuss and analyze four magic-angle spinning solid-state NMR methods that can be used to measure internuclear distances and to obtain correlation spectra between a spin I = 1/2 and a half-integer spin S > 1/2 having a small quadrupolar coupling constant. Three of the methods are based on the heteronuclear multiple-quantum and single-quantum correlation experiments, that is, high rank tensors that involve the half spin and the quadrupolar spin are generated. Here, both zero and single-quantum coherence of the half spins are allowed and various coherence orders of the quadrupolar spin are generated, and filtered, via active recoupling of the dipolar interaction. As a result of generating coherence orders larger than one, the spectral resolution for the quadrupolar nucleus increases linearly with the coherence order. Since the formation of high rank tensors is independent of the existence of a finite quadrupolar interaction, these experiments are also suitable to materials in which there is high symmetry around the quadrupolar spin. A fourth experiment is based on the initial quadrupolar-driven excitation of symmetric high order coherences (up to p = 2S, where S is the spin number) and subsequently generating by the heteronuclear dipolar interaction higher rank (l + 1 or higher) tensors that involve also the half spins. Due to the nature of this technique, it also provides information on the relative orientations of the quadrupolar and dipolar interaction tensors. For the ideal case in which the pulses are sufficiently strong with respect to other interactions, we derive analytical expressions for all experiments as well as for the transferred echo double resonance experiment involving a quadrupolar spin. We show by comparison of the fitting of simulations and the analytical expressions to experimental data that the analytical expressions are sufficiently accurate to provide experimental (7)Li-(13)C distances in a complex of lithium, glycine, and water. Discussion

  3. A high-pressure polarized 3He gas target for nuclear-physics experiments using a polarized photon beam

    NASA Astrophysics Data System (ADS)

    Ye, Q.; Laskaris, G.; Chen, W.; Gao, H.; Zheng, W.; Zong, X.; Averett, T.; Cates, G. D.; Tobias, W. A.

    2010-04-01

    Following the first experiment on three-body photodisintegration of polarized 3He utilizing circularly polarized photons from High-Intensity Gamma Source (HI γ S) at Duke Free Electron Laser Laboratory (DFELL), a new high-pressure polarized 3He target cell made of pyrex glass coated with a thin layer of sol-gel doped with aluminum nitrate nonahydrate has been built in order to reduce the photon beam-induced background. The target is based on the technique of spin exchange optical pumping of hybrid rubidium and potassium and the highest polarization achieved is ˜ 62% determined from both NMR-AFP and EPR polarimetries. The phenomenological parameter that reflects the additional unknown spin relaxation processes, X , is estimated to be ˜ 0.10 and the performance of the target is in good agreement with theoretical predictions. We also present beam test results from this new target cell and the comparison with the GE180 3He target cell used previously at HI γ S. This is the first time that the sol-gel coating technique has been used in a polarized 3He target for nuclear-physics experiments.

  4. NMR Studies of 3He Films on Boron Nitride

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Sullivan, N. S.

    2014-12-01

    We report the results of NMR studies of the dynamics of 3He adsorbed on hexagonal boron nitride. These studies can identify the phase transitions of the 2D films as a function of temperature. A thermally activated temperature dependence is observed for 2.6 < T < 8 K compared to a linear temperature dependence for 0.7 < T < 2.6 K. This linear dependence is consistent with that expected for thermal diffusion in a fluid for coverages of 0.4 - 0.6 of a monolayer.

  5. Hard Photodisintegration of Proton Pairs in {sup 3}He

    SciTech Connect

    Piasetzky, Eli; Pomerantz, Ishay; Higinbotham, D.; Strauch, S.; Gilman, R.

    2008-10-13

    Hard deuteron photodisintegration has been investigated for 20 years, as its cross section follows the constituent counting rule and it provides insight into the interplay between hadronic and quark-gluon degrees of freedom in high-momentum transfer exclusive reactions. We have now measured for the first time hard pp-pair disintegration in the reaction {gamma}{sup 3}He{yields}pp+n, using kinematics corresponding to a spectator neutron. Cross sections were measured for 90 deg. c.m. at 8 beam energies, from 0.8 to 4.7 GeV. Preliminary results will be presented and compared to the hard deuteron photodisintegration data.

  6. High-pressure /sup 3/He gas scintillation neutron spectrometer

    SciTech Connect

    Derzon, M.S.; Slaughter, D.R.; Prussin, S.G.

    1985-10-01

    A high-pressure, /sup 3/He-Xe gas scintillation spectrometer has been developed for neutron spectroscopy on D-D fusion plasmas. The spectrometer exhibits an energy resolution of (121 +- 20 keV) keV (FWHM) at 2.5 MeV and an efficiency of (1.9 +- 0.4) x 10/sup -3/ (n/cm/sup 2/)/sup -1/. The contribution to the resolution (FWHM) from counting statistics is only (22 +- 3 keV) and the remainder is due predominantly to the variation of light collection efficiency with location of neutron events within the active volume of the detector.

  7. Isospin effects in the exclusive dp 3He reaction

    NASA Astrophysics Data System (ADS)

    Mielke, M.; Burmeister, I.; Chiladze, D.; Dymov, S.; Fritzsch, C.; Gebel, R.; Goslawski, P.; Hartmann, M.; Kacharava, A.; Khoukaz, A.; Kulessa, P.; Lorentz, B.; Mersmann, T.; Mikirtychiants, S.; Ohm, H.; Papenbrock, M.; Rausmann, T.; Serdyuk, V.; Ströher, H.; Täschner, A.; Valdau, Yu.; Wilkin, C.

    2014-06-01

    The differential cross section for the exclusive reaction has been measured with high resolution and large statistics over a large fraction of the backward 3He hemisphere at the excess energy 265 MeV using the COSY-ANKE magnetic spectrometer. Though the well-known ABC enhancement is observed in the spectrum, the differences detected between the and invariant-mass distributions show that there must be some isospin-one production even at relatively low excess energies. The invariant-mass differences are modeled in terms of the sequential decay.

  8. Fermion Monte Carlo Calculations on Liquid-3He

    SciTech Connect

    Kalos, M H; Colletti, L; Pederiva, F

    2004-03-16

    Methods and results for calculations of the ground state energy of the bulk system of {sup 3}He atoms are discussed. Results are encouraging: they believe that they demonstrate that their methods offer a solution of the ''fermion sign problem'' and the possibility of direct computation of many-fermion systems with no uncontrolled approximations. Nevertheless, the method is still rather inefficient compared with variational or fixed-node approximate methods. There appears to be a significant populations size effect. The situation is improved by the inclusion of ''Second Stage Importance Sampling'' and of ''Acceptance/Rejection'' adapted to their needs.

  9. High-momentum response of liquid 3He.

    PubMed

    Mazzanti, F; Polls, A; Boronat, J; Casulleras, J

    2004-02-27

    A final-state-effects formalism suitable to analyze the high-momentum response of Fermi liquids is presented and used to study the dynamic structure function of liquid 3He. The theory, developed as a natural extension of the Gersch-Rodriguez formalism, incorporates the Fermi statistics explicitly through a new additive term which depends on the semidiagonal two-body density matrix. The use of a realistic momentum distribution, calculated using the diffusion Monte Carlo method, and the inclusion of this additive correction allows for good agreement with available deep-inelastic neutron scattering data. PMID:14995785

  10. A p-spin high-pass filter using radiofrequency field gradients for homonuclear magnetic resonance experiments

    NASA Astrophysics Data System (ADS)

    Canet, Daniel; Mutzenhardt, Pierre; Brondeau, Jean

    Traditional multiple-quantum filtering in nuclear magnetic resonance spectroscopy relies on the acquisition of several transients along with appropriate phase cycling. It is shown that similar results can be obtained in one transient by using a cluster of two radiofrequency field (B1) gradient pulses (g1)x(rg1)y where g1 and rg1 denote the durations of the B1 gradient pulses and the subscripts x and y the transmitter phases. This filter acts on single-quantum antiphase coherences and is of high-pass nature. The choice of r determines the order of the filter (according to the number of spins belonging to the system considered). This property is demonstrated theoretically and verified experimentally by dedicated one-dimensional experiments and COSY-type two-dimensional experiments.

  11. Quantum Phase Transition of 3He in Aerogel at a Nonzero Pressure

    NASA Astrophysics Data System (ADS)

    Matsumoto, K.; Porto, J. V.; Pollack, L.; Smith, E. N.; Ho, T. L.; Parpia, J. M.

    1997-07-01

    We present evidence for a nonzero pressure, T = 0 superfluid phase transition of 3He in 98.2% open aerogel. Unlike bulk 3He which is a superfluid at T = 0 at all pressures (densities) between zero and the melting pressure, 3He in aerogel is not superfluid unless the 3He density exceeds a critical value ρc. About 90% of the 3He added above ρc contributes to the superfluid density.

  12. Simulation of detector signals in n+3 He --> p + t

    NASA Astrophysics Data System (ADS)

    Coppola, Christopher; n3He Collaboration

    2015-10-01

    The parity violating proton directional asymmetry from the capture of polarized neutrons on 3He is being measured with a pulsed neutron beam at the Spallation Neutron Source at Oak Ridge National Laboratory. The target is an ion chamber with 3He at approximately half an atmosphere. Signal wires at different locations in the chamber have different sensitivities to the physics asymmetry, which are determined by the geometry and configuration of the experiment. These geometry factors must be determined by simulation. In addition, a simulation can estimate the statistical precision of the experiment, optimize configuration variables, and assist with error analysis. To achieve the most accurate simulation of the detector signals, a custom simulation was written in C++ using weighted variables and taking advantage of parallel execution. The inputs used to construct the simulation came from measurements of the neutron phase space, ENDF cross sections, and PSTAR ionization data. A cell model was used to combine this physics to produce an accurate simulation of the experimental data. This simulation can be used to calculate accurate and tunable geometry factors, and to produce desired quanities for use in optimization and analysis.

  13. Source investigation of impulsive 3He-rich particle events

    NASA Astrophysics Data System (ADS)

    Tan, Chengming; Yan, Yihua

    We have investigated the source characteristic and coronal magnetic field structure of six impulsive solar energetic particle (SEP) events selected from Wang et al. [Wang, Y.-M., Pick, M., Mason, G.M. Coronal holes, jets, and the origin of 3He-rich particle events. ApJ 639, 495, 2006] and Pick et al. [Pick, M., Mason, G.M., Wang, Y.-M., Tan, C., Wang, L. Solar source regions for 3He-rich solar energetic particle events identified using imaging radio, optical, and energetic particle observations. ApJ 648, 1247, 2006]. Some results are obtained: first, 2 events are associated with wide (≈100°) CMEs (hereafter wide CME events), another 4 events are associated with narrow (⩽40°) CMEs (hereafter narrow CME events); second, the coronal magnetic field configuration of narrow CME events appear more simple than that of the wide CME events; third, the photospheric magnetic field evolutions of all these events show new emergence of fluxes, while one case also shows magnetic flux cancellation; fourth, the EUV jets usually occurred very close to the footpoint of the magnetic field loop, while meter type III bursts occurred near or at the top of the loop and higher than EUV jets. Furthermore, the heights of type III bursts are estimated from the result of the coronal magnetic field extrapolations.

  14. Liquid and Solid Phases of 3He on Graphite

    NASA Astrophysics Data System (ADS)

    Gordillo, M. C.; Boronat, J.

    2016-04-01

    Recent heat-capacity experiments show quite unambiguously the existence of a liquid 3He phase adsorbed on graphite. This liquid is stable at an extremely low density, possibly one of the lowest found in nature. Previous theoretical calculations of the same system, and in strictly two dimensions, agree with the result that this liquid phase is not stable and the system is in the gas phase. We calculated the phase diagram of normal 3He adsorbed on graphite at T =0 using quantum Monte Carlo methods. Considering a fully corrugated substrate, we observe that at densities lower than 0.006 Å-2 the system is a very dilute gas that, at that density, is in equilibrium with a liquid of density 0.014 Å-2 . Our prediction matches very well the recent experimental findings on the same system. On the contrary, when a flat substrate is considered, no gas-liquid coexistence is found, in agreement with previous calculations. We also report results on the different solid structures, and on the corresponding phase transitions that appear at higher densities.

  15. The 3H-3He Charge Radii Difference

    NASA Astrophysics Data System (ADS)

    Myers, L. S.; Arrington, J. R.; Higinbotham, D. W.

    2016-03-01

    The upcoming E12-14-009 [1] experiment at Jefferson Lab will determine the ratio of the electric form factors for the A=3 mirror nuclei 3He and 3H. The measurement will use a 1.1 GeV electron beam, a special collimator plate to allow for simultaneous optics measurements, and the low-activity tritium target being prepared for Jefferson Lab. By observing the dependence of the form factor ratio as a function of Q2 over 0.05-0.09 GeV2, the dependence of the radii extraction on the shape of the form factors is minimized. As a result, we anticipate the uncertainty of the extracted charge radii difference to be 0.03 fm, a reduction of 70% from the current measurement. Using precise measurements of the 3He charge radius from isotopic shift or μHe measurements [2-4], we can deduce the absolute 3H charge radius. The results will provide a direct comparison to recent calculations of the charge radii.

  16. Double-quantum vortex in superfluid 3He-A

    PubMed

    Blaauwgeers; Eltsov; Krusius; Ruohio; Schanen; Volovik

    2000-03-30

    Linear defects are generic in continuous media. In quantum systems they appear as topological line defects which are associated with a circulating persistent current. In relativistic quantum field theories they are known as cosmic strings, in superconductors as quantized flux lines, and in superfluids and low-density Bose-Einstein condensates as quantized vortex lines. A conventional quantized vortex line consists of a central core around which the phase of the order parameter winds by 27(pi)n, while within the core the order parameter vanishes or is depleted from the bulk value. Usually vortices are singly quantized (that is, have n = 1). But it has been theoretically predicted that, in superfluid 3He-A, vortex lines are possible that have n = 2 and continuous structure, so that the orientation of the multicomponent order parameter changes smoothly throughout the vortex while the amplitude remains constant. Here we report direct proof, based on high-resolution nuclear magnetic resonance measurements, that the most common vortex line in 3He-A has n = 2. One vortex line after another is observed to form in a regular periodic process, similar to a phase-slip in the Josephson effect. PMID:10761908

  17. Hard photodisintegration of a proton pair in {sup 3}He

    SciTech Connect

    Stanley Brodsky; Leonid Frankfurt; Ronald Gilman; J. R. Hiller; G. A. Miller; Eliezer Piasetzky; Misak Sargsian; Mark Strikman

    2003-05-01

    Hard photodisintegration of the deuteron has been extensively studied in order to understand the dynamics of the transition from hadronic to quark-gluon descriptions of the strong interaction. In this work, we discuss the extension of this program to hard photodisintegration of a pp pair in the {sup 3}He nucleus. Experimental confirmation of new features predicted here for the suggested reaction would advance our understanding of hard nuclear reactions. A main prediction, in contrast with low-energy observations, is that the pp breakup cross section is not much smaller than the one for pn break up. In some models, the energy-dependent oscillations observed for pp scattering are predicted to appear in the {gamma} {sup 3}He {yields} pp + n reaction. Such an observation would open up a completely new field in studies of color coherence phenomena in hard nuclear reactions. We also demonstrate that, in addition to the energy dependence, the measurement of the light-cone momentum distribution of the recoil neutron provides an independent test of the underlying dynamics of hard disintegration.

  18. Lowest vibrational states of {sup 4}He{sup 3}He{sup +}: Non-Born-Oppenheimer calculations

    SciTech Connect

    Stanke, Monika; Bubin, Sergiy; Kedziera, Dariusz; Molski, Marcin; Adamowicz, Ludwik

    2007-11-15

    Very accurate quantum mechanical calculations of the first five vibrational states of the {sup 4}He{sup 3}He{sup +} molecular ion are reported. The calculations have been performed explicitly including the coupling of the electronic and nuclear motions [i.e., without assuming the Born-Oppenheimer (BO) approximation]. The nonrelativistic non-BO wave functions were used to calculate the {alpha}{sup 2} relativistic mass velocity, Darwin, and spin-spin interaction corrections. For the lowest vibrational transition, whose experimental energy is established with high precision, the calculated and the experimental results differ by only 0.16 cm{sup -1}.

  19. Light Higgs channel of the resonant decay of magnon condensate in superfluid 3He-B

    PubMed Central

    Zavjalov, V. V.; Autti, S.; Eltsov, V. B.; Heikkinen, P. J.; Volovik, G. E.

    2016-01-01

    In superfluids the order parameter, which describes spontaneous symmetry breaking, is an analogue of the Higgs field in the Standard Model of particle physics. Oscillations of the field amplitude are massive Higgs bosons, while oscillations of the orientation are massless Nambu-Goldstone bosons. The 125 GeV Higgs boson, discovered at Large Hadron Collider, is light compared with electroweak energy scale. Here, we show that such light Higgs exists in superfluid 3He-B, where one of three Nambu-Goldstone spin-wave modes acquires small mass due to the spin–orbit interaction. Other modes become optical and acoustic magnons. We observe parametric decay of Bose-Einstein condensate of optical magnons to light Higgs modes and decay of optical to acoustic magnons. Formation of a light Higgs from a Nambu-Goldstone mode observed in 3He-B opens a possibility that such scenario can be realized in other systems, where violation of some hidden symmetry is possible, including the Standard Model. PMID:26743951

  20. A Study of Hadronic Weak Interaction - The n3He Experiment at SNS

    NASA Astrophysics Data System (ADS)

    Kabir, Latiful

    2015-10-01

    While parity violation (PV) is well-understood at the quark and lepton level, it is much more elusive in hadronic systems, being dominated by several orders of magnitude by the strong interaction. However, studies of PV in hadronic systems offer a unique probe of nucleon structure, complementary to other probes of low-energy non-perturbative QCD. The n3He experiment at the spallation neutron source at ORNL is motivated to probe the Hadronic Weak Interaction (HWI) by measuring the parity violating spin asymmetry of the recoil proton in the reaction n + 3He --> p +T +765 KeV. This is sensitive to ΔI = 0 and 1 components of the HWI, and is expected to be extremely small (of the order of 10-7). The experiment aims to determine this PV asymmetry with the statistical sensitivity of the order of 10-8. The experiment is now in the data taking phase and will continue until the end of the year. I will describe the experiment and give its current status.

  1. A Metastability-Exchange Optical Pumping and Compression System using Polarized 3 He for a Proposed Laboratory Search for Neutron Monopole-Dipole Interactions

    NASA Astrophysics Data System (ADS)

    Smith, Erick; Ariadne Collaboration

    2015-04-01

    3 He nuclei polarized using the metastability-exchange optical pumping (MEOP) method have been used for scientific applications such as magnetometry in space, neutron polarization and analysis, and medical imaging. In this talk we explain how this technique is also well-suited for a proposed experiment to search for possible monopole-dipole interactions of polarized 3 He nuclei with matter. The P-odd and T-odd monopole-dipole potential proposed by Moody and Wilczek is proportional to s-> . r-> where s-> is the 3 He spin and r-> is the separation between the particles. It can be induced by axions, and ARIADNE proposes to perform NMR on a polarized 3 He ensemble at 4K with a radially-slotted tungsten disk spinning at a multiple of the 3 He Larmour frequency to induce a resonant monopole-dipole perturbation. The radial slot length variations are chosen to maximize sensitivity to a monopole-dipole interaction range corresponding to the axion window. We describe the advantages that MEOP presents for this experiment and describe the MEOP-based polarized 3 He gas compression system at Indiana University.

  2. Conductance and spin-filter effects of oxygen-incorporated Au, Cu, and Fe single-atom chains

    SciTech Connect

    Zheng, Xiaolong; Xie, Yi-Qun Ye, Xiang; Ke, San-Huang

    2015-01-28

    We studied the spin-polarized electron transport in oxygen-incorporated Au, Cu, and Fe single-atom chains (SACs) by first-principles calculations. We first investigated the mechanism responsible for the low conductance (<1G{sub 0}) of the Au and Cu SACs in an oxygen environment reported in recent experiments. We found that for the Au SACs, the low conductance plateau around 0.6G{sub 0} can be attributed to a distorted chain doped with a single oxygen atom, while the 0.1G{sub 0} conductance comes from a linear chain incorporated with an oxygen molecule and is caused by an antibonding state formed by oxygen's occupied frontier orbital with d{sub z} orbitals of adjacent Au atoms. For the Cu SACs, the conductance about 0.3G{sub 0} is ascribed to a special configuration that contains Cu and O atoms in an alternating sequence. This exhibits an even-odd conductance oscillation with an amplitude of ∼0.1G{sub 0}. In contrast, for the alternating Fe-O SACs, conductance overall decreases with an increase in O atoms and it approaches nearly zero for the chain with more than four O atoms. While the Cu-O SACs behave as perfect spin filters for one spin channel due to the half metallic nature, the Fe-O SACs can serve as perfect spin filters for two spin channels depending on the polarity of the applied gate voltage.

  3. Perfect spin-valley filter controlled by electric field in ferromagnetic silicene

    SciTech Connect

    Soodchomshom, Bumned E-mail: fscibns@ku.ac.th

    2014-01-14

    The spin-valley currents in silicene-based normal/sublattice-dependent ferromagnetic/normal junction are investigated. Unlike that in graphene, the pseudo Dirac mass in silicene is generated by spin-orbit interaction and tunable by applying electric or exchange fields into it. This is due to silicon-based honeycomb lattice having buckled structure. As a result, it is found that the junction leads to currents perfectly split into four groups, spin up (down) in k- and k{sup ′}-valleys, when applying different values of the electric field, considered as a perfect spin-valley polarization (PSVP) for electronic application. The PSVP is due to the interplay of spin-valley-dependent Dirac mass and chemical potential in the barrier. The PSVP also occurs only for the energy comparable to the spin-orbit energy gap. This work reveals potential of silicene for spinvalleytronics applications.

  4. Graphene sheet versus two-dimensional electron gas: A relativistic Fano spin filter via STM and AFM tips

    NASA Astrophysics Data System (ADS)

    Seridonio, A. C.; Siqueira, E. C.; Souza, F. M.; Machado, R. S.; Lyra, S. S.; Shelykh, I. A.

    2013-11-01

    We explore theoretically the density of states (LDOS) probed by a scanning tunneling microscope (STM) tip of two-dimensional systems hosting an adatom and a subsurface impurity, both capacitively coupled to atomic force microscope (AFM) tips and traversed by antiparallel magnetic fields. Two kinds of setups are analyzed, a monolayer of graphene and a two-dimensional electron gas (2DEG). The AFM tips set the impurity levels at the Fermi energy, where two contrasting behaviors emerge: The Fano factor for the graphene diverges, while in the 2DEG it approaches zero. As result, the spin degeneracy of the LDOS is lifted exclusively in the graphene system, in particular, for the asymmetric regime of Fano interference. The aftermath of this limit is a counterintuitive phenomenon, which consists of a dominant Fano factor due to the subsurface impurity even with a stronger STM-adatom coupling. Thus we find a full polarized conductance, achievable just by displacing vertically the position of the STM tip. Our work proposes the Fano effect as the mechanism to filter spins in graphene. This feature arises from the massless Dirac electrons within the band structure and allows us to employ the graphene host as a relativistic Fano spin filter.

  5. {sup 3}He target for Hall C at CEBAF

    SciTech Connect

    Zeidman, B.; Zeuli, A.

    1995-08-01

    A major fraction of the physics program for Hall C involves scattering from cryogenic targets of the lightest nuclei, i.e. H, D, and {sup 3,4}He. Argonne is constructing the He target that will consist of a 4cm cylinder, operating at a pressure of 10 atmospheres and a temperature of {approximately}5.2 degrees Kelvin. CEBAF is currently constructing a cryo-target system for liquid H and D cells and the cooled, pressurized helium targets. The He target system includes cell loop, the He supply systems, and the additional equipment needed to ensure minimum loss of {sup 3}He in the event of target rupture. Some of the major components have been completed, while the balance of the system will be ready for installation this fiscal year.

  6. Event identification in 3He proportional counters using risetime discrimination

    NASA Astrophysics Data System (ADS)

    Langford, T. J.; Bass, C. D.; Beise, E. J.; Breuer, H.; Erwin, D. K.; Heimbach, C. R.; Nico, J. S.

    2013-07-01

    We present a straightforward method for particle identification and background rejection in 3He proportional counters for use in neutron detection. By measuring the risetime and pulse height of the preamplifier signals, one may define a region in the risetime versus pulse height space where the events are predominately from neutron interactions. For six proportional counters surveyed in a low-background environment, we demonstrate the ability to reject alpha-particle events with an efficiency of 99%. By applying the same method, we also show an effective rejection of microdischarge noise events that, when passed through a shaping amplifier, are indistinguishable from physical events in the counters. The primary application of this method is in measurements where the signal-to-background for counting neutrons is very low, such as in underground laboratories.

  7. Direct energy conversion system for D(3)-He fusion

    NASA Astrophysics Data System (ADS)

    Tomita, Y.; Shu, L. Y.; Momota, H.

    1993-11-01

    A novel and highly efficient direct energy conversion system is proposed for utilizing D(3)-He fueled fusion. In order to convert kinetic energy of ions, we applied a pair of direct energy conversion systems each of which has a cusp-type DEC and a traveling wave DEC (TWDEC). In a cusp-type DEC, electrons are separated from the escaping ions at the first line-cusp and the energy of thermal ion components is converted at the second cusp DEC. The fusion protons go through the cusp-type DEC and arrive at the TWDEC, which principle is similar to 'LINAC'. The energy of fusion protons is recovered to electricity with an efficiency of more than 70%. These DEC's bring about the high efficient fusion plant.

  8. Perspectives of hyperpolarized noble gas MRI beyond 3He

    PubMed Central

    Lilburn, David M.L.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2013-01-01

    Nuclear Magnetic Resonance (NMR) studies with hyperpolarized (hp) noble gases are at an exciting interface between physics, chemistry, materials science and biomedical sciences. This paper intends to provide a brief overview and outlook of magnetic resonance imaging (MRI) with hp noble gases other than hp 3He. A particular focus are the many intriguing experiments with 129Xe, some of which have already matured to useful MRI protocols, while others display high potential for future MRI applications. Quite naturally for MRI applications the major usage so far has been for biomedical research but perspectives for engineering and materials science studies are also provided. In addition, the prospects for surface sensitive contrast with hp 83Kr MRI is discussed. PMID:23290627

  9. Stability of superfluid 3He-B in compressed aerogel.

    PubMed

    Li, J I A; Zimmerman, A M; Pollanen, J; Collett, C A; Gannon, W J; Halperin, W P

    2014-03-21

    In recent work, it was shown that new anisotropic p-wave states of superfluid (3)He can be stabilized within high-porosity silica aerogel under uniform positive strain. In contrast, the equilibrium phase in an unstrained aerogel is the isotropic superfluid B phase. Here we report that this phase stability depends on the sign of the strain. For a negative strain of ∼ 20% achieved by compression, the B phase can be made more stable than the anisotropic A phase, resulting in a tricritical point for A, B, and normal phases with a critical field of ∼ 100 mT. From pulsed NMR measurements, we identify these phases and the orientation of the angular momentum. PMID:24702386

  10. APT {sup 3}He target/blanket. Topical report

    SciTech Connect

    1995-03-01

    The {sup 3}He target/blanket (T/B) preconceptual design for the 3/8-Goal facility is based on a 1000-MeV, 200-mA accelerator to produce a high-intensity proton beam that is expanded and then strikes one of two T/B modules. Each module consists of a centralized neutron source made of tungsten and lead, a proton beam backstop region made of zirconium and lead, and a moderator made of D{sub 2}O. Helium-3 gas is circulated through the neutron source region and the blanket to create tritium through neutron capture. The gas is continually processed to extract the tritium with an online separation process.

  11. Isotopic separation of sup 3 He/ sup 4 He from solar wind gases evolved from the lunar regolith

    SciTech Connect

    Wilkes, W.R. ); Wittenberg, L.J. )

    1992-01-01

    The potential benefits of {sup 3}He when utilized in a nuclear fusion reactor to provide clean, safe electricity in the 21st century for the world's inhabitants has been documented. Unfortunately, He is scarce on earth. Large quantities of {sup 3}He, perhaps a million tonnes, are embedded in the lunar regolith, presumably implanted by the solar wind together with other elements, notably {sup 4}He, H, C and N. Several studies have suggested processing the lunar regolith and recovering these valuable solar wind gases. Once released, these gases can be separated for use. The separation of helium isotopes is described in this paper. {sup 3}He constitutes only 400 at{center dot}ppm of lunar He, too dilute to separate economically by distillation alone. A superfluid'' separator is being considered to preconcentrate the {sup 3}He. The superfluid separator consists of a porous filter in a tube maintained at a temperature of 2.17 K or less. Although the {sup 4}He, which is superfluid below 2.17 K, flows readily through the filter, the He is blocked by the filter, and becomes enriched at the feed end. He can be enriched to about 10% in such a system. The enriched product from the superfluid separation serves as a feed to a distillation apparatus operating at a pressure of 9 kPa, with a boiler temperature of 2.4 K, and a condenser temperature of 1.6 K. Under constant flow conditions, a 99.9% enriched He product can be produced in this apparatus. The heat rejection load of the refrigeration equipment necessary to cool the separation operations would be conducted during the lunar nights.

  12. Isotopic separation of {sup 3}He/{sup 4}He from solar wind gases evolved from the lunar regolith

    SciTech Connect

    Wilkes, W.R.; Wittenberg, L.J.

    1992-09-01

    The potential benefits of {sup 3}He when utilized in a nuclear fusion reactor to provide clean, safe electricity in the 21st century for the world`s inhabitants has been documented. Unfortunately, He is scarce on earth. Large quantities of {sup 3}He, perhaps a million tonnes, are embedded in the lunar regolith, presumably implanted by the solar wind together with other elements, notably {sup 4}He, H, C and N. Several studies have suggested processing the lunar regolith and recovering these valuable solar wind gases. Once released, these gases can be separated for use. The separation of helium isotopes is described in this paper. {sup 3}He constitutes only 400 at{center_dot}ppm of lunar He, too dilute to separate economically by distillation alone. A ``superfluid`` separator is being considered to preconcentrate the {sup 3}He. The superfluid separator consists of a porous filter in a tube maintained at a temperature of 2.17 K or less. Although the {sup 4}He, which is superfluid below 2.17 K, flows readily through the filter, the He is blocked by the filter, and becomes enriched at the feed end. He can be enriched to about 10% in such a system. The enriched product from the superfluid separation serves as a feed to a distillation apparatus operating at a pressure of 9 kPa, with a boiler temperature of 2.4 K, and a condenser temperature of 1.6 K. Under constant flow conditions, a 99.9% enriched He product can be produced in this apparatus. The heat rejection load of the refrigeration equipment necessary to cool the separation operations would be conducted during the lunar nights.

  13. Exploration of kinetic and multiple-ion-fluids effects in D3He and T3He gas-filled ICF implosions using multiple nuclear reaction histories

    NASA Astrophysics Data System (ADS)

    Sio, Hong; Rinderknecht, Hans; Rosenberg, Michael; Zylstra, Alex; Séguin, Fredrick; Gatu Johnson, Maria; Li, Chikang; Petrasso, Richard; Hoffman, Nelson; Kagan, Krigory; Molvig, Kim; Amendt, Peter; Bellei, Claudio; Wilks, Scott; Stoeckl, Christian; Glebov, Vladimir; Betti, Riccardo; Sangster, Thomas; Katz, Joseph

    2014-10-01

    To explore kinetic and multi-ion-fluid effects in D3He and T3He gas-filled shock-driven implosions, multiple nuclear reaction histories were measured using the upgraded Particle Temporal Diagnostic (PTD) on OMEGA. For D3He gas-filled implosions, the relative timing of the DD and D3He reaction histories were measured with 20 ps precision. For T3He gas-filled implosions (with 1-2% deuterium), the relative timing of the DT and D3He reaction histories were measured with 10 ps precision. The observed differences between the reaction histories on these two OMEGA experiments are contrasted to 1-D single-ion hydro simulations for different gas-fill pressure and gas mixture. This work is supported in part by the U.S. DOE, LLNL, LLE, and NNSA SSGF.

  14. A Kalman Filter for Mass Property and Thrust Identification of the Spin-Stabilized Magnetospheric Multiscale Formation

    NASA Technical Reports Server (NTRS)

    Queen, Steven Z.

    2015-01-01

    The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories, elliptically orbiting the Earth in a tetrahedron formation. For the operational success of the mission, on-board systems must be able to deliver high-precision orbital adjustment maneuvers. On MMS, this is accomplished using feedback from on-board star sensors in tandem with accelerometers whose measurements are dynamically corrected for errors associated with a spinning platform. In order to determine the required corrections to the measured acceleration, precise estimates of attitude, rate, and mass-properties are necessary. To this end, both an on-board and ground-based Multiplicative Extended Kalman Filter (MEKF) were formulated and implemented in order to estimate the dynamic and quasi-static properties of the spacecraft.

  15. Transport properties of bare and hydrogenated zigzag silicene nanoribbons: Negative differential resistances and perfect spin-filtering effects

    SciTech Connect

    Yang, X. F.; Liu, Y. S. Feng, J. F.; Wang, X. F.; Zhang, C. W.; Chi, F.

    2014-09-28

    Ab initio calculations are performed to investigate the spin-polarized transport properties of the bare and hydrogenated zigzag silicene nanoribbons (ZSiNRs). The results show that the ZSiNRs with symmetric (asymmetric) edges prefer the ferromagnetic (antiferromagnetic) as their ground states with the semiconductor properties, while the accordingly antiferromagnetic (ferromagnetic) states exhibit the metallic behaviors. These facts result in a giant magnetoresistance behavior between the ferromagnetic and antiferromagnetic states in the low bias-voltage regime. Moreover, in the ferromagnetic ZSiNRs with asymmetric edges, a perfect spin-filtering effect with 100% positive electric current polarization can be achieved by altering the bias voltage. In addition, we also find that the negative differential resistances prefer the metastable states. The findings here indicate that the asymmetric and symmetric ZSiNRs are promising materials for spintronic applications.

  16. Spin-valley filter and tunnel magnetoresistance in asymmetrical silicene magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Wang, Dali; Huang, Zeyuan; Zhang, Yongyou; Jin, Guojun

    2016-05-01

    The spin and valley transports and tunnel magnetoresistance are studied in a silicene-based asymmetrical magnetic tunnel junction consisting of a ferromagnetic tunnel barrier, sandwiched between a ferromagnetic electrode and a normal electrode. For such an asymmetrical silicene junction, a general formulism is established. The numerical results show that the spin-valley resolved conductances strongly depend on the magnetization orientation of the ferromagnetic tunnel barrier, and the fully spin-valley polarized current can be realized by tuning a perpendicularly applied electric field. We also find that the tunnel magnetoresistance in this case can be effectively modified by the external electric field when the conductance is fully spin-valley polarized. In particular, the exchange field in the ferromagnetic electrode can further substantially enhance the tunnel magnetoresistance of the system. Our work provides a practical method for electric and magnetic manipulation of valley/spin polarization and tunnel magnetoresistance.

  17. The contribution of the {}^3He(γ ,n)pp reaction to the GDH integrand below pion production threshold

    NASA Astrophysics Data System (ADS)

    Laskaris, G.

    2016-03-01

    The first measurements of the three-body phototdisintegration of 3He polarized parallel and anti-parallel to a circularly polarized γ-ray beam were carried out at the High Intensity γ-ray Source (HIγS) facility located at Triangle Universities Nuclear Laboratory (TUNL). A high pressure 3He target, polarized via spin-exchange optical pumping with alkali metals, was used in the experiments. The neutrons from the three-body photodisintegration were detected with sixteen 12.7 cm diameter liquid scintillator detectors. The spin-dependent cross sections and the contributions from the three-body photodisintegration to the 3He Gerasimov-Drell-Hearn sum rule integrand were extracted and compared with state-of-the-art three-body calculations at the incident photon energies of 12.8, 14.7, and 16.5 MeV. The calculations, which include the Coulomb interaction are in good agreement with the results of the measurements at 12.8 and 14.7 MeV but deviate from the results at 16.5 MeV.

  18. Neutron Multiplicity Measurements With 3He Alternative: Straw Neutron Detectors

    DOE PAGESBeta

    Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; Detweiler, Ryan; Maurer, Richard J.; Mitchell, Stephen E.; Guss, Paul P.; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions ofmore » neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and developed a data acquisition (DAQ) system to collect

  19. Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

    DOE PAGESBeta

    Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; Detweiler, Ryan; Maurer, Richard J.; Mitchell, Stephen E.; Guss, Paul P.; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions ofmore » neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and developed a data acquisition (DAQ) system to collect

  20. Determining Exchange Splitting in a Magnetic Semiconductor by Spin-Filter Tunneling

    SciTech Connect

    Santos, T. S.; Moodera, J. S.; Venkataraman, K.; Negusse, E.; Holroyd, J.; Dvorak, J.; Liberati, M.; Idzerda, Y. U.; Arenholz, E.

    2008-06-24

    A large exchange splitting of the conduction band in ultrathin films of the ferromagnetic semiconductor EuO was determined quantitatively, by using EuO as a tunnel barrier and fitting the current-voltage characteristics and temperature dependence to tunneling theory. This exchange splitting leads to different tunnel barrier heights for spin-up and spin-down electrons, and is large enough to produce a near fully spin-polarized current. Moreover, the magnetic properties of these ultrathin films (<6 nm) show a reduction in Curie temperature with decreasing thickness, in agreement with theoretical calculation [R. Schiller et al., Phys. Rev. Lett. 86, 3847 (2001)].

  1. Comment on "Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis".

    PubMed

    Balser, Dana S; Rood, Robert T; Bania, T M

    2007-08-31

    Eggleton et al. (Reports, 8 December 2006, p. 1580) reported on a deep-mixing mechanism in low-mass stars caused by a Rayleigh-Taylor instability that destroys all of the helium isotope 3He produced during the star's lifetime. Observations of 3He in planetary nebulae, however, indicate that some stars produce prodigious amounts of 3He. This is inconsistent with the claim that all low-mass stars should destroy 3He. PMID:17761865

  2. Equilibrium helical order in radially confined superfluid 3He

    NASA Astrophysics Data System (ADS)

    Wiman, Joshua; Sauls, J. A.

    An exciting prediction of confined superfluid 3He is the presence of spontaneously broken translational symmetry, resulting in a superfluid phase that has a different translational symmetry than that of the confining geometry. Such phases have been described theoretically in films, cylinders, and ribbons. We predict an inhomogeneous superfluid phase with helical order that is energetically stable within cylindrical channels of radius comparable to the Cooper pair coherence length. By incorporating extensions to standard Ginzburg-Landau (GL) strong-coupling theory that accurately reproduce the bulk phase diagram at high pressures and allow tuneable boundary conditions, we find this new phase to be stable at both high and low pressures and favored by boundary conditions with strong pairbreaking. We present superfluid phase diagrams as functions of pressure, temperature, and channel radius showing the regions of stability for this ``spiral'' phase relative to those phases previously predicted for the channel. Transverse NMR frequency shifts are a possible experimental signature of this phase, and we present calculations of these shifts as functions of rf pulse tipping angle, field orientation, and temperature. Supported by NSF Grant DMR-1508730.

  3. Hydrogen trapping in 3He-irradiated Fe

    NASA Astrophysics Data System (ADS)

    Takagi, Ikuji; Matsuoka, Kotaro; Tanaka, Toshiyuki; Akiyoshi, Masafumi; Sasaki, Takayuki

    2013-11-01

    The characteristics of irradiation-induced hydrogen (deuterium) traps in pure Fe were investigated for quantitative evaluation of tritium retention in fusion reactor components. The deuterium depth profiles of an Fe disk sample exposed to deuterium plasma were observed by means of nuclear reaction analysis (NRA) before and after irradiation with 0.8 MeV or 1.3 MeV 3He ions. Irradiation generated a number of traps, and deuterium retention was drastically increased subsequent to irradiation. Steady-state deuterium concentration in the trap and the solution sites were obtained by continuously charging the sample with deuterium during the NRA. Based on these values, the trapping energy, which is the enthalpy difference between the two sites, was estimated to be 0.38 eV. The number ratio of the trap to atomic displacement was 0.013. Some of the traps were annihilated around 523 K. The annihilation temperature, the trapping energy, and the equilibrium constant suggest that the trap is a dislocation loop introduced by the irradiation. It is deduced that the tritium inventory in the Fe components of a reactor should be drastically increased by neutron irradiation due to the formation of traps, but may be significantly reduced by high temperature operation of the components.

  4. Measurement of the Coherent Neutron Scattering Length of 3He

    PubMed Central

    Ketter, W.; Heil, W.; Badurek, G.; Baron, M.; Loidl, R.; Rauch, H.

    2005-01-01

    By means of neutron interferometry the s-wave neutron scattering length of the 3He nucleus was re-measured at the Institut Laue-Langevin (ILL). Using a skew symmetrical perfect crystal Si-interferometer and a linear twin chamber cell, false phase shifts due to sample misalignment were reduced to a negligible level. Simulation calculations suggest an asymmetrically alternating measuring sequence in order to compensate for systematic errors caused by thermal phase drifts. There is evidence in the experiment’s data that this procedure is indeed effective. The neutron refractive index in terms of Sears’ exact expression for the scattering amplitude has been analyzed in order to evaluate the measured phase shifts. The result of our measurement, b′c = (6.000 ± 0.009) fm, shows a deviation towards a greater value compared to the presently accepted value of b′c = (5.74 ± 0.07) fm, confirming the observation of the partner experiment at NIST. On the other hand, the results of both precision measurements at NIST and ILL exhibit a serious 12σ (12 standard uncertainties) deviation, the reason for which is not clear yet.

  5. Optical interferometry in superfluid {sup 3}He-B

    SciTech Connect

    Alles, H.; Ruutu, J.P.; Babkin, A.V.; Hakonen, P.J.; Sonin, E.B.

    1996-03-01

    The authors report interferometric measurements in 0.1...1 mm thick films of superfluid {sup 3}He-B. The menisci of three different rotational states of the superfluid were observed and analyzed theoretically using two-fluid hydrodynamics: These are (i) the equilibrium vortex state in which the superfluid and the normal components corotate (solid body rotation), (ii) the vortex-free state (the Landau state), in which only the normal component rotates, and (iii) the quasistationary vortex state in which only the superfluid fraction rotates (pure superfluid rotation). The Landua state manifested itself by a reduced parabolic meniscus at rotation speeds below the critical angular velocity {Omega}{sub c}{approx_lt} 0.2 rad/s for vortex formation. Transition from the Landua state to the equilibrium vortex state yielded a sudden deepening of the meniscus when {Omega}{sub c} was exceeded. After a rapid halt of the cryostat, the authors observed a novel meniscus which was produced by the superfluid rotation while the normal component was at rest. The enhanced depth of this meniscus is governed by the reactive mutual friction parameter B{prime}. By employing laser light, both for imaging and for thermomechanical excitation, the authors measured the response of a thin superfluid layer to a heat pulse and analyzed it within the theory of two fluid hydrodynamics. The data were employed, using the dispersion relation for thin film oscillations, to deduce the second viscosity coefficient {zeta}{sub 3} close to T{sub c}.

  6. Quantum Simulation via Filtered Hamiltonian Engineering: Application to Perfect Quantum Transport in Spin Networks

    NASA Astrophysics Data System (ADS)

    Ajoy, Ashok; Cappellaro, Paola

    2013-05-01

    We propose a method for Hamiltonian engineering that requires no local control but only relies on collective qubit rotations and field gradients. The technique achieves a spatial modulation of the coupling strengths via a dynamical construction of a weighting function combined with a Bragg grating. As an example, we demonstrate how to generate the ideal Hamiltonian for perfect quantum information transport between two separated nodes of a large spin network. We engineer a spin chain with optimal couplings starting from a large spin network, such as one naturally occurring in crystals, while decoupling all unwanted interactions. For realistic experimental parameters, our method can be used to drive almost perfect quantum information transport at room temperature. The Hamiltonian engineering method can be made more robust under decoherence and coupling disorder by a novel apodization scheme. Thus, the method is quite general and can be used to engineer the Hamiltonian of many complex spin lattices with different topologies and interactions.

  7. Quantum simulation via filtered Hamiltonian engineering: application to perfect quantum transport in spin networks.

    PubMed

    Ajoy, Ashok; Cappellaro, Paola

    2013-05-31

    We propose a method for Hamiltonian engineering that requires no local control but only relies on collective qubit rotations and field gradients. The technique achieves a spatial modulation of the coupling strengths via a dynamical construction of a weighting function combined with a Bragg grating. As an example, we demonstrate how to generate the ideal Hamiltonian for perfect quantum information transport between two separated nodes of a large spin network. We engineer a spin chain with optimal couplings starting from a large spin network, such as one naturally occurring in crystals, while decoupling all unwanted interactions. For realistic experimental parameters, our method can be used to drive almost perfect quantum information transport at room temperature. The Hamiltonian engineering method can be made more robust under decoherence and coupling disorder by a novel apodization scheme. Thus, the method is quite general and can be used to engineer the Hamiltonian of many complex spin lattices with different topologies and interactions. PMID:23767705

  8. Temporal Variability in the Accretion Rate of Interplanetary Dust Using (3)He as a Tracer

    NASA Technical Reports Server (NTRS)

    Farley, K. A.

    2005-01-01

    The research supported by this grant falls under three topics: 1) Weekly Interplanetary Dust Sampling via (3)He; 2) Extraterrestrial (3)He at Major Impact Boundaries; 3) Completing a Moderately-High Resolution Record of Extraterrestrial (3)He Flux: A Major Asteroidal Break up Event at 8.2 Ma.

  9. Properties of InGaAs/InAlAs double quantum wells toward spin-filtering application

    NASA Astrophysics Data System (ADS)

    Koga, Takaaki; Yokota, Shoichiro; Yamashige, Takashi; Sawada, Atsushi; Matsuura, Toru; Faniel, Sebastien; Souma, Satofumi; Sekine, Yoshiaki; Sugiyama, Hiroki

    2014-03-01

    We recently determined the intrinsic constant for the Rashba effect in (001)InP-matched InGaAs/InAlAs quantum wells (QW). We now apply this knowledge to band-engineer a spin-filter based on the double QW (DQW). Firstly, we studied the subband energy spectra of the InGaAs/InAlAs DQW from the beatings in the Shubnikov de Haas (SdH) oscillations. The basic properties obtained here provide useful information to refine the device structures for the spin-filter devices based on the DQW system. In our DQW samples, a thin barrier layer of In0.52Al0.48As (dB = 1.5 ~5 nm) is sandwiched with non-doped QW layers of In0.53Ga0.47As (dQW = 10 nm). By carefully tuning the doping densities above and below the DQW part and the top-gate voltage, the potential profile of this DQW should be ideally made symmetric about the middle barrier layer, though not yet realized in our experiment. The experimental results of our not-yet-ideal DQW samples showed clear beatings in the SdH data, which originate from both the subband and Rashba splittings. We report on our successful separation of these two effects based on the proper band-bending assumptions. This work was supported by JSPS KAKENHI Grant Number 23360001.

  10. Transfer Excitation Processes Observed in N3+-He and O3+-He Collisions at Elab = 33 eV

    NASA Astrophysics Data System (ADS)

    Itoh, Yoh

    2016-09-01

    We measured the relative state-selective differential cross sections (DCSs) for one-electron capture reactions using a crossed-beam apparatus. The scattering angle θlab studied in the laboratory frame ranged from -3.0 to 22° and the laboratory collision energy Elab was 33 eV. Only the transfer excitation processes, i.e., the electron capture reactions with the simultaneous excitation of the projectile, were observed. The DCSs were determined for the following reactions: N3+ (1s2 2s2 1S) + He (1s2 1S) → N2+ (1s2 2s2p2 2D) + He+ (1s 2S) + 10.3 eV, O3+ (1s2 2s2 2p 2P) + He (1s2 1S) → O2+ (1s2 2s 2p3 3P) + He+ (1s 2S) + 12.7 eV, and O3+ (1s2 2s2 2p 2P) + He (1s2 1S) → O2+ (1s2 2s 2p3 3D) + He+ (1s 2S) + 15.5 eV. In the N3+-He system, the DCSs for the reaction are zero at the center-of-mass angle θcm = 0 and show a peak at a certain angle and a shoulder at a larger angle. In the O3+-He system, the DCSs are again zero at θcm = 0. The capture process to the O2+ (1s2 2s 2p3 3P) state is mainly observed at smaller scattering angles, and the reaction to the O2+ (1s2 2s 2p3 3D) state becomes dominant with increasing scattering angle. A classical trajectory analysis within the two-state approximation based on the ab initio potentials for (NHe)3+ revealed that the transfer excitation of a two-electron process takes place through a single crossing of the relevant potentials.

  11. Electron screening and stellar rates in the {sup 3}He({sup 3}He,2p){sup 4}He and {sup 3}He(d,p){sup 4}He fusion reactions

    SciTech Connect

    Messahel, L.; Ouichaoui, S.; Belhout, A.; Fouka, M.; Trabelsi, A.

    2008-05-12

    The astrophysical S(E) factor experimental data available over the energy region E (C.M.)<1.0 MeV for the {sup 3}He({sup 3}He,2p){sup 4}He and {sup 3}He(d,p){sup 4}He fusion reactions are analyzed using a polynomial expression and the R-Matrix formalism, respectively. The reaction thermonuclear rates for bare nuclei are determined and compared to previous ones after a precise assessment of the electron screening factors. New level parameter values are deduced for the {sup 5}Li nucleus.

  12. Spin-filtered Edge States with an Electrically Tunable Gap in a Two-Dimensional Topological Crystallin Insulator

    NASA Astrophysics Data System (ADS)

    Liu, Junwei; Hsieh, Timothy H.; Wei, Peng; Duan, Wenhui; Moodera, Jagadeesh; Fu, Liang

    2014-03-01

    Three-dimensional topological crystalline insulators (TCIs) were recently predicted and observed in the SnTe class of IV-VI semiconductors, which host metallic surface states protected by crystal symmetries. In this work, we study thin films of these materials and expose their potential device applications. We demonstrate that thin films of SnTe and Pb1-xSnxSe(Te) grown along the (001) direction are topologically nontrivial in a wide range of film thickness and carry conducting spin-filtered edge states that are protected by the (001) mirror symmetry via a topological invariant. Application of an electric field perpendicular to the film will break the mirror symmetry and generate a band gap in these edge states. This functionality motivates us to propose a novel topological transistor device, in which charge and spin transport are maximally entangled and simultaneously controlled by an electric field. The high on/off operation speed and coupling of spin and charge in such a device may lead to electronic and spintronic applications for TCIs. This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0010526.

  13. Spin filtering in a double quantum dot device: Numerical renormalization group study of the internal structure of the Kondo state

    SciTech Connect

    Vernek, E.; Büsser, C. A.; Anda, E. V.; Feiguin, A. E.; Martins, G. B.

    2014-03-31

    A double quantum dot device, connected to two channels that only interact through interdot Coulomb repulsion, is analyzed using the numerical renormalization group technique. Using a two-impurity Anderson model, and realistic parameter values [S. Amasha, A. J. Keller, I. G. Rau, A. Carmi, J. A. Katine, H. Shtrikman, Y. Oreg, and D. Goldhaber-Gordon, Phys. Rev. Lett. 110, 046604 (2013)], it is shown that, by applying a moderate magnetic field and independently adjusting the gate potential of each quantum dot at half-filling, a spin-orbital SU(2) Kondo state can be achieved where the Kondo resonance originates from spatially separated parts of the device. Our results clearly link this spatial separation effect to currents with opposing spin polarizations in each channel, i.e., the device acts as a spin filter. In addition, an experimental probe of this polarization effect is suggested, pointing to the exciting possibility of experimentally probing the internal structure of an SU(2) Kondo state.

  14. New type of magnetic tunnel junction based on spin filtering through a reduced symmetry oxide: FeCo|Mg3B2O6|FeCo.

    PubMed

    Stewart, Derek A

    2010-01-01

    Magnetic tunnel junctions with high-tunneling magnetoresistance values such as Fe|MgO|Fe capitalize on spin filtering in the oxide region based on the band symmetry of incident electrons. However, these structures rely on magnetic leads and oxide regions of the same cubic symmetry class. A new magnetic tunnel junction (FeCo|Mg(3)B(2)O(6)|FeCo) is presented that uses a reduced symmetry oxide region (orthorhombic) to provide spin filtering between the two cubic magnetic leads. Complex band structure analysis of Mg(3)B(2)O(6) based on density functional calculations shows that significant spin filtering could occur in this system. This new type of magnetic tunnel junction may have been fabricated already and can explain recent experimental studies of rf-sputtered FeCoB|MgO|FeCoB junctions where there is significant B diffusion into the MgO region. PMID:20017563

  15. Nonlinear development of strong current-driven instabilities and selective acceleration of ^3He ions

    NASA Astrophysics Data System (ADS)

    Toida, Mieko; Okumura, Hayato

    2003-10-01

    In some solar flares, the abundance of high-energy ^3He ions is extremely increased. As a mechanism for these ^3He rich events, current-driven instabilities are believed to be important. Nonlinear development of the strong current-driven instabilities and associated energy transfer to ^3He ions are studied theoretically and numerically [1]. First, by means of a two-dimensional, electrostatic, particle simulation code, it is demonstrated that ^3He ions are selectively accelerated by fundamental H cyclotron waves with frequencies ω ≃ 2Ω_3He (Ω_3He is the cyclotron frequency of ^3He). Then, from the analysis of the dispersion relation of these waves, it is found that the ω ≃ 2 Ω_ 3He waves have the greatest growth rate, if Te > 10 T_H. Energies of the ^3He ions are also discussed. Theoretical expression for the maximum ^3He energy is presented, which is in good agreement with the simulation results. Based on this theory, it is shown that when the initial electron drift energy is of the order of 10 keV, many ^3He ions can be accelerated to energies of the order of MeV/n. [1] M. Toida and H. Okumura, J. Phys. Soc. Jpn. 72,1098 (2003)

  16. Transport in ultradilute solutions of 3He in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Baym, Gordon; Beck, D. H.; Pethick, C. J.

    2015-07-01

    We calculate the effect of a heat current on transporting 3He dissolved in superfluid 4He at ultralow concentration, as will be utilized in a proposed experimental search for the electric dipole moment of the neutron (nEDM). In this experiment, a phonon wind will be generated to drive (partly depolarized) 3He down a long pipe. In the regime of 3He concentrations ≲10-9 and temperatures ˜0.5 K, the phonons comprising the heat current are kept in a flowing local equilibrium by small angle phonon-phonon scattering, while they transfer momentum to the walls via the 4He first viscosity. On the other hand, the phonon wind drives the 3He out of local equilibrium via phonon-3He scattering. For temperatures below 0.5 K, both the phonon and 3He mean free paths can reach the centimeter scale, and we calculate the effects on the transport coefficients. We derive the relevant transport coefficients, the phonon thermal conductivity, and the 3He diffusion constants from the Boltzmann equation. We calculate the effect of scattering from the walls of the pipe and show that it may be characterized by the average distance from points inside the pipe to the walls. The temporal evolution of the spatial distribution of the 3He atoms is determined by the time dependent 3He diffusion equation, which describes the competition between advection by the phonon wind and 3He diffusion. As a consequence of the thermal diffusivity being small compared with the 3He diffusivity, the scale height of the final 3He distribution is much smaller than that of the temperature gradient. We present exact solutions of the time dependent temperature and 3He distributions in terms of a complete set of normal modes.

  17. Spin-filtering, giant magnetoresistance, rectifying and negative differential resistance effects in planar four-coordinate Fe complex with graphene nanoribbon electrodes

    SciTech Connect

    Zhao, P. E-mail: ss-cheng@ujn.edu.cn; Wu, Q. H.; Chen, G. E-mail: ss-cheng@ujn.edu.cn; Liu, D. S.; Department of Physics, Jining University, Qufu 273155

    2014-01-28

    By using the nonequilibrium Green's function formalism combined with the density functional theory, we have investigated the spin-polarized transport properties of a planar four-coordinate Fe complex sandwiched between two zigzag-edge graphene nanoribbon (ZGNR) electrodes, where the ZGNRs are modulated by external magnetic field. The results show that the system can exhibit perfect dual spin-filtering and spin-rectifying effects at a wide bias range, giant magnetoresistance effect with large magnetoresistance ratio at small bias, and obvious negative differential resistance behavior. The mechanisms are proposed for these phenomena.

  18. Spin-filtering effect of thin Al{sub 2}O{sub 3} barrier on tunneling magnetoresistance

    SciTech Connect

    Joo, Sungjung; Jung, K. Y.; Jun, K. I.; Shin, K. H.; Kim, D. S.; Hong, J. K.; Rhie, K. E-mail: krhie@korea.ac.kr; Lee, B. C. E-mail: krhie@korea.ac.kr

    2014-04-14

    Tunneling magnetoresistance (TMR) dependence on the Al{sub 2}O{sub 3} barrier thickness was investigated for CoFe/Al{sub 2}O{sub 3}/CoFe magnetic tunnel junctions (MTJs). MTJs with very thin Al{sub 2}O{sub 3} layers were grown by inserting an amorphous FeZr buffer layer whose role is only to reduce the roughness of bottom electrode. The TMR decreased as the thickness of the Al{sub 2}O{sub 3} layer was reduced. The results are analyzed with the dependence of the spin-filtering effect on the Al{sub 2}O{sub 3} thickness. It was found that a simple model of separating sp- and d-like electrons does not work, and it may suggest that the tunneling electrons are in rather hybridized state.

  19. Perfect Spin-filtering in graphene monolayer-bilayer superlattice with zigzag boundaries

    NASA Astrophysics Data System (ADS)

    Yu, Hang; Liu, Jun-Feng

    2016-05-01

    We show that the spontaneous magnetization is formed at the zigzag boundary between monolayer and bilayer graphene by the self-consistent calculation based on Hubbard model. In a monolayer- bilayer graphene superlattice with zigzag boundaries, it is surprising that nearly 100% spin polarization is achieved in the energy window around the Dirac point, no matter the magnetization configuration at two boundaries is parallel or antiparallel. The reason is that the low-energy transport is only influenced by the magnetization at one edge, but not by that at the other. The underlying physics is unveiled by the spin-split band structure and the distribution of the wave-function pertaining to the lowest (highest) subband of electron (hole).

  20. Perfect Spin-filtering in graphene monolayer-bilayer superlattice with zigzag boundaries.

    PubMed

    Yu, Hang; Liu, Jun-Feng

    2016-01-01

    We show that the spontaneous magnetization is formed at the zigzag boundary between monolayer and bilayer graphene by the self-consistent calculation based on Hubbard model. In a monolayer- bilayer graphene superlattice with zigzag boundaries, it is surprising that nearly 100% spin polarization is achieved in the energy window around the Dirac point, no matter the magnetization configuration at two boundaries is parallel or antiparallel. The reason is that the low-energy transport is only influenced by the magnetization at one edge, but not by that at the other. The underlying physics is unveiled by the spin-split band structure and the distribution of the wave-function pertaining to the lowest (highest) subband of electron (hole). PMID:27140666

  1. Perfect Spin-filtering in graphene monolayer-bilayer superlattice with zigzag boundaries

    PubMed Central

    Yu, Hang; Liu, Jun-Feng

    2016-01-01

    We show that the spontaneous magnetization is formed at the zigzag boundary between monolayer and bilayer graphene by the self-consistent calculation based on Hubbard model. In a monolayer- bilayer graphene superlattice with zigzag boundaries, it is surprising that nearly 100% spin polarization is achieved in the energy window around the Dirac point, no matter the magnetization configuration at two boundaries is parallel or antiparallel. The reason is that the low-energy transport is only influenced by the magnetization at one edge, but not by that at the other. The underlying physics is unveiled by the spin-split band structure and the distribution of the wave-function pertaining to the lowest (highest) subband of electron (hole). PMID:27140666

  2. Spin filtering and entanglement swapping through coherent evolution of a single quantum dot.

    PubMed

    Coello, Jose Garcia; Bayat, Abolfazl; Bose, Sougato; Jefferson, John H; Creffield, Charles E

    2010-08-20

    We exploit the nondissipative dynamics of a pair of electrons in a large square quantum dot to perform singlet-triplet spin measurement through a single charge detection and show how this may be used for entanglement swapping and teleportation. The method is also used to generate the Affleck-Kennedy-Lieb-Tasaki ground state, a further resource for quantum computation. We justify, and derive analytic results for, an effective charge-spin Hamiltonian which is valid over a wide range of parameters and agrees well with exact numerical results of a realistic effective-mass model. Our analysis also indicates that the method is robust to the choice of dot-size and initialization errors, as well as decoherence. PMID:20868084

  3. A possible in situ 3H and 3He source in Earth's interior: an alternative explanation of origin of 3He in deep Earth.

    PubMed

    Jiang, Songsheng; Liu, Jing; He, Ming

    2010-07-01

    Origin of (3)He in the Earth is a mystery. Lacking a production mechanism, scientists assume (3)He was trapped in the Earth, when the Earth was formed. In contrast to this assumption, we have found (3)He and (3)H concentrations in excess of the atmospheric values in the deep waters of the volcanic Lakes Pavin (France), Laacher (Germany) and Nemrut (Turkey). This paper reports the result of finding (3)H in these three volcanic lakes that appear to originate from the mantle. Because (3)H has a half-life of 12.3 years, this (3)H and the resulting (3)He must have formed recently in the mantle and not be part of a primordial reservoir. The nuclear reactions that generate tritium might be a source of "missing" energy in the interior of the Earth. PMID:20502855

  4. A 3He Cryostat for Scientific Measurements in Pulsed High Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Wang, Shaoliang; Li, Liang; Liu, Mengyu; Zuo, Huakun; Peng, Tao

    A top loading 3He cryostat has been developed for scientific experiments with a 60 T pulsed magnetic field facility at Wuhan National High Magnetic Field Center. The cryostat consists of a 4He bath cryostat, a 3He insert and a closed circulation system for 3He gas handling. To eliminate the eddy current heating during the pulse, the tail of the 3He insert with a vacuum space at the bottom is made from fiberglass tubing coated with epoxy. The 3He bath is separated from the 4He bath with the vacuum space. The 4He bath cryostat provides cooling power to condense 3He gas by a neck tube on top of the tail. Experimental results have shown that the sample can be cooled down to 385 mK and kept cold for more than 150 second by one-shot cooling, which is sufficiently long for an experiment in a pulsed high magnetic field.

  5. Fabrication and tests of 3He and 2H targets for beam polarization measurement

    PubMed

    Naqvi; Aksoy; Nagadi; Al-Ohali; Kidwai; Fageeha

    2000-09-01

    3He and 2H targets were fabricated through implantation of 3He and 2H ions in 0.2-0.3 mm thick tantalum and titanium foils. The energy of 3He and 2H ions was 45-100 and 78 keV, respectively. Ions beams with typical current of 90-300 microA were used for implantation. Stability tests of 3He and 2H targets were carried out by monitoring the yield of 3He(d, p)4He and 2H(d, p)3H reactions. For the 3He target, the reaction yield was stable for both tantalum and titanium foils but the most stabilized maximum yield was observed for the 100 keV tantalum target. In the case of 2H targets, the yield increased with increasing total dose implanted on the target. PMID:10972150

  6. NMR Studies of Texture in the B-like Phase of 3He in Aerogel

    SciTech Connect

    Dmitriev, V. V.; Zavjalov, V. V.; Zmeev, D. E.; Mulders, N.

    2006-09-07

    Continuous wave NMR experiments have been performed in the B-like phase of 3He in a 98% open aerogel. The results allow us to get information about the texture of the 3He order parameter inside the aerogel. We conclude that in the B-like phase the boundary between the bulk 3He and the aerogel orients the vector of orbital anisotropy (L) parallel to it. Two stable textures and textural transition between them were observed in our sample.

  7. A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D{sup 3}He and DT implosions at the NIF

    SciTech Connect

    Rinderknecht, H. G.; Johnson, M. Gatu; Zylstra, A. B.; Sinenian, N.; Rosenberg, M. J.; Frenje, J. A.; Waugh, C. J.; Li, C. K.; Seguin, F. H.; Petrasso, R. D.; Rygg, J. R.; Kimbrough, J. R.; MacPhee, A.; Collins, G. W.; Hicks, D.; Mackinnon, A.; Bell, P.; Bionta, R.; Clancy, T.; Zacharias, R.; and others

    2012-10-15

    The particle-time-of-flight (pTOF) diagnostic, fielded alongside a wedge range-filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted {rho}R measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT exploding pusher, and D{sup 3}He implosions using DD or DT neutrons with an accuracy better than {+-}70 ps. In the second phase of the project, a deflecting magnet will be incorporated into the pTOF design for simultaneous measurements of shock- and compression-bang times in D{sup 3}He-filled surrogate implosions using D{sup 3}He protons and DD-neutrons, respectively.

  8. Massless surface waves between two different superfluid phases of 3He

    NASA Astrophysics Data System (ADS)

    Todoshchenko, I.

    2016-04-01

    An interface between two media is a topologically stable two-dimensional object where 3D-symmetry breaks which allows for the existence of many exotic excitations. A direct way to explore surface excitations is to investigate their interaction with the surface waves, such as very well known capillary-gravity waves and crystallization waves. Helium remains liquid down to absolute zero where bulk excitations are frozen out and do not mask the interaction of the waves with the surface states. Here we show the possibility of the massless wave which can propagate along the surface between two different superfluids phases of 3He . The displacement of the surface in this wave occurs due to the transition of helium atoms from one phase to another, so that there is no flow of particles as densities of phases are equal. We calculate the dispersion of the wave in which the inertia is provided by spin supercurrents, and the restoring force is magnetic field gradient. We calculate the dissipation of the wave and show the preferable conditions to observe it.

  9. NMR Properties of the Polar Phase of Superfluid ^3He in Anisotropic Aerogel Under Rotation

    NASA Astrophysics Data System (ADS)

    Mineev, V. P.

    2016-09-01

    The polar phase of superfluid ^3He is stable in "nematically ordered" densed aerogel. A rotating vessel with the polar superfluid can be filled either by an array of the single quantum vortices or by an array of the half-quantum vortices. It is shown that the inhomogeneous distribution of the spin part of the order parameter arising in an array of half-quantum vortices in strong enough magnetic field tilted to the average direction of aerogel strands leads to the appearance of a satellite in the NMR signal shifted in the negative direction with respect to the Larmor frequency. The satellite is absent in the case of an array of single quantum vortices which allows to distinguish these two configurations. The polar state in the anisotropic aerogel with lower density transforms at lower temperatures to the axipolar state. The array of half-quantum vortices created in the polar phase keeps its structure under transition to the axipolar state. The temperature dependence of the vortex-satellite NMR frequency is found to be slower below the transition temperature to the axipolar state.

  10. NMR Properties of the Polar Phase of Superfluid ^3 He in Anisotropic Aerogel Under Rotation

    NASA Astrophysics Data System (ADS)

    Mineev, V. P.

    2016-04-01

    The polar phase of superfluid ^3 He is stable in "nematically ordered" densed aerogel. A rotating vessel with the polar superfluid can be filled either by an array of the single quantum vortices or by an array of the half-quantum vortices. It is shown that the inhomogeneous distribution of the spin part of the order parameter arising in an array of half-quantum vortices in strong enough magnetic field tilted to the average direction of aerogel strands leads to the appearance of a satellite in the NMR signal shifted in the negative direction with respect to the Larmor frequency. The satellite is absent in the case of an array of single quantum vortices which allows to distinguish these two configurations. The polar state in the anisotropic aerogel with lower density transforms at lower temperatures to the axipolar state. The array of half-quantum vortices created in the polar phase keeps its structure under transition to the axipolar state. The temperature dependence of the vortex-satellite NMR frequency is found to be slower below the transition temperature to the axipolar state.

  11. Two-Body Electrodisintegration of $^3$He at High Momentum Transfer

    SciTech Connect

    R. Schiavilla; O. Benhar; A. Kievsky; L.E. Marcucci; M. Viviani

    2005-08-01

    The {sup 3}He (e,e{prime}p)d reaction is studied using an accurate three-nucleon bound state wave function, a model for the electromagnetic current operator including one- and two-body terms, and the Glauber approximation for the treatment of final state interactions. In contrast to earlier studies, the profile operator in the Glauber expansion is derived from a nucleon-nucleon scattering amplitude, which retains its full spin and isospin dependence and is consistent with phase-shift analyses of two-nucleon scattering data. The amplitude is boosted from the center-of-mass frame, where parameterizations for it are available, to the frame where rescattering occurs. Exact Monte Carlo methods are used to evaluate the relevant matrix elements of the electromagnetic current operator. The predicted cross section is found to be in quantitative agreement with the experimental data for values of the missing momentum p{sub m} in the range (0--700) MeV/c, but underestimates the data at p{sub m} {approx} 1 GeV/c by about a factor of two. However, the longitudinal-transverse asymmetry, measured up to p{sub m} {approx} 600 MeV/c, is well reproduced by theory. A critical comparison is carried out between the results obtained in the present work and those of earlier studies.

  12. 3He comagnetometer readout using SQUIDs in the neutron electric dipole moment (nEDM) experiment at SNS

    NASA Astrophysics Data System (ADS)

    Clayton, Steven; Kim, Young; nEDM Collaboration

    2013-04-01

    The nEDM collaboration is developing a new experiment to measure the neutron's electric dipole moment to ~10-28 e-cm. A non-zero neutron EDM would be the first observation of CP violation in a baryon containing only light quarks, while a null result would be inconsistent with predictions from most variants of supersymmetry. The experiment will measure the difference in spin precession, of polarized ultracold neutrons (UCN) produced and stored in a superfluid-helium-filled cell, when the magnetic and electric fields are parallel and antiparallel. A key feature of the experimental method is the use of polarized 3He atoms within the cell acting as both spin analyzer and comagnetometer to the UCN. In one mode of running, the 3He precession signal is detected by SQUID gradiometers adjacent to the cell. This talk will cover recent experimental studies of a prototype SQUID gradiometer suitable for the nEDM experiment. This work was supported by DOE Office Of Science, Nuclear Physics.

  13. 3 He Co-magnetometer Readout for the SNS nEDM Experiment

    NASA Astrophysics Data System (ADS)

    Kim, Young Jin; Clayton, Steven

    2014-09-01

    A search for a permanent electric dipole moment (EDM) of the neutron would provide one of the most important low energy tests of the discrete symmetries beyond the Standard Model of particle physics. A new experimental search of neutron EDM, to be conducted at the Spallation Neutron Source (SNS) at ORNL, has been proposed with a goal of 100-fold improvement in the present experimental limit of 10-26e .cm The experiment is based on the magnetic-resonance technique in which polarized neutrons precess at the Larmor frequency when placed in a static magnetic field; a non-zero EDM would be evident as a difference in precession frequency when a strong electric field is applied parallel vs. anti-parallel to the magnetic field. In addition to its role as neutron spin-analyzer via the spin-dependent n+3He nuclear capture process, polarized helium-3 (which has negligible EDM) will serve as co-magnetometer to correct for drifts in the magnetic field. The helium-3 co-magnetometer will be directly read out by superconducting gradiometers coupled to SQUIDs. We describe a proposed SQUID system suitable for the complex neutron EDM apparatus, and demonstrate that the field noise in the SQUID system, tested in an environment similar to the EDM apparatus, meets the nEDM requirement. We also present a test of the compatibility of low-noise SQUID operation with other devices, potential sources of electromagnetic interference, which are necessarily operating during the EDM measurement period and effective ambient magnetic field noise cancellation with an implementation of reference channels.

  14. Estimation of p-bar beam polarization due to spin filtering by a polarized hydrogen target

    SciTech Connect

    Strakhovenko, V.

    2008-04-30

    The polarization buildup in a p-bar beam due to the interaction of stored antiprotons with polarized protons of a hydrogen target is considered. The corresponding cross section is calculated in the energy interval 20filtering mechanism can provide a noticeable polarization in a time comparable with the beam lifetime.

  15. Spin filtering and magneto-resistive effect at the graphene/h-BN ribbon interface.

    PubMed

    Dubois, Simon Mutien-Marie; Declerck, Xavier; Charlier, J-C; Payne, Michael C

    2013-05-28

    Advances in the realization of hybrid graphene/h-BN materials open new ways to control the electronic properties of graphene nanostructures. In this paper, the structural, electronic, and transport properties of heterojunctions made of bare zigzag-shaped h-BN and graphene ribbons are investigated using first-principles techniques. Our results highlight the potential of graphene/h-BN junctions for applications in spintronic devices. At first, density functional theory is used to detail the role played by the edge states and dangling bonds in the electronic and magnetic behavior of h-BN and graphene ribbons. Then, the electronic conductance of the junction is computed in the framework of Green's function-based scattering theory. In its high-spin configuration, the junction reveals a full spin polarization of the propagating carriers around the Fermi energy, and the magnitude of the transmission probability is predicted to be strongly dependent on the relative orientation of magnetic momenta in the leads. PMID:23641732

  16. First detection of 3He+ in the planetary nebula IC 418

    NASA Astrophysics Data System (ADS)

    Guzman-Ramirez, L.; Rizzo, J. R.; Zijlstra, A. A.; García-Miró, C.; Morisset, C.; Gray, M. D.

    2016-07-01

    The 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in low-mass stars which evolve through the planetary nebula (PN) phase. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. We present the detection of the 3He+ emission line using the single dish Deep Space Station 63, towards the PN IC 418. We derived a 3He/H abundance in the range 1.74 ± 0.8 × 10-3 to 5.8 ± 1.7 × 10-3, depending on whether part of the line arises in an outer ionized halo. The lower value for 3He/H ratio approaches values predicted by stellar models which include thermohaline mixing, but requires that large amounts of 3He are produced inside low-mass stars which enrich the interstellar medium (ISM). However, this overpredicts the 3He abundance in H II regions, the ISM, and protosolar grains, which is known to be of the order of 10-5. This discrepancy questions our understanding of the evolution of the 3He, from circumstellar environments to the ISM.

  17. Possible Dimensional Crossover to 1D of ^3He Fluid in Nanochannels Observed in Susceptibilities

    NASA Astrophysics Data System (ADS)

    Matsushita, Taku; Kurebayashi, Katsuya; Shibatsuji, Ryosuke; Hieda, Mitsunori; Wada, Nobuo

    2016-05-01

    Dimensional crossover to the one-dimensional (1D) state from higher dimensions has been studied for dilute ^3He fluid adsorbed in 2.4 nm ^4He-preplated nanochannels, by susceptibility measurements down to 70 mK using 4.29 MHz nuclear magnetic resonance. In nanochannels, since energy states of ^3He motion perpendicular to the channel axis are discrete, a genuine 1D ^3He fluid is expected when the Fermi energy is less than the first excitation Δ _{01} for azimuthal motion. The susceptibilities χ above 0.3 K show the Curie-law susceptibilities independent of the ^3He density, which are characteristic of nondegenerate fluid in higher dimensions. With decreasing the temperature, a significant reduction of χ T was observed from about 0.3 K for all ^3He densities. It is considered to be due to the dimensional crossover below Δ _{01}˜ 0.5 K to the 1D ^3He state in the semi-degenerate regime above the Fermi temperature. In the 1D state at lower temperatures, T-independent χ were observed for ^3He of 0.019 layers below 0.1 K. It suggests that the 1D ^3He fluid enters the quantum degenerate regime.

  18. Design of an Ion Source for {sup 3}He Fusion in a Low Pressure IEC Device

    SciTech Connect

    Piefer, Gregory R.; Santarius, John F.; Ashley, Robert P.; Kulcinski, Gerald L.

    2005-05-15

    Recent developments in helicon ion sources and Inertial Electrostatic Confinement (IEC) device performance at UW-Madison have enabled low pressure (< 50 {mu}torr, 6.7 mPa) operating conditions that should allow the {sup 3}He-{sup 3}He fusion reaction to be observed in an IEC device. An ion source capable of delivering a {approx} 10 mA {sup 3}He ion beam into an IEC device with minimal neutral gas flow has been designed and tested. Furthermore, a new IEC device that has never been operated with deuterium has been constructed to avoid D-{sup 3}He protons from obstructing the {sup 3}He-{sup 3}He reaction product spectrum, and to minimize Penning ionization of deuterium by excited helium, which in the past is suspected to have limited the ionized density of He. These developments make it possible to study beam-background {sup 3}He-{sup 3}He fusion reactions with > 300 mA recirculating ion currents.

  19. First Detection of 3He+ in the Planetary Nebula IC 418

    NASA Astrophysics Data System (ADS)

    Guzman-Ramirez, L.; Rizzo, J. R.; Zijlstra, A. A.; García-Miró, C.; Morisset, C.; Gray, M. D.

    2016-04-01

    The 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in low-mass stars which evolve through the planetary nebula (PN) phase. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. We present the detection of the 3He+ emission line using the single dish Deep Space Station 63, towards the PN IC 418. We derived a 3He/H abundance in the range 1.74±0.8×10-3 to 5.8±1.7×10-3, depending on whether part of the line arises in an outer ionized halo. The lower value for 3He/H ratio approaches values predicted by stellar models which include thermohaline mixing, but requires that large amounts of 3He are produced inside low-mass stars which enrich the interstellar medium (ISM). However, this over-predicts the 3He abundance in H II regions, the ISM, and proto-solar grains, which is known to be of the order of 10-5. This discrepancy questions our understanding of the evolution of the 3He, from circumstellar environments to the ISM.

  20. Measurement of fast minority /sub 3/He/sup + +/ energy distribution during ICRF heating

    DOEpatents

    Post, D.E. Jr.; Grisham, L.R.; Medley, S.S.

    A method and means for measuring the fast /sub 3/He/sup + +/ distribution during /sub 3/He/sup + +/ minority Ion Cyclotron Resonance Frequency (ICRF) heating is disclosed. The present invention involves the use of 10 to 100 keV beams of neutral helium atoms to neutralize the fast /sub 3/He/sup + +/ ions in a heated plasma by double charge exchange (/sub 3/He/sup + +/ + /sub 4/He/sup 0/ ..-->.. /sub 3/He/sup 0/ + /sub 4/He/sup + +/). The neutralized fast /sub 3/He/sup 0/ atoms then escape from the hot plasma confined by a magnetic field and are detected by conventional neutral particle analyzing means. This technique permits the effectiveness of the coupling of the ion cyclotron waves to the /sub 3/He/sup + +/ minority ions to be accurately measured. The present invention is particularly adapted for use in evaluating the effectiveness of the intermediate coupling between the RF heating and the /sub 3/He/sup + +/ in an energetic toroidal plasma.

  1. First measurement of the helicity dependence of 3He photoreactions in the Δ(1232) resonance region

    NASA Astrophysics Data System (ADS)

    Costanza, Susanna

    2014-03-01

    The first measurement of the helicity dependence for several photo-reaction channels on 3He was carried out in the photon energy range between 150 and 500 MeV at the MAMI accelerator (Mainz). The experiment used the large acceptance Crystal Ball spectrometer, complemented by charged particle and vertex detectors, a circularly polarised tagged photon beam and a longitudinally polarised high-pressure 3He gas target. Results of the helicity dependent total inclusive photoabsorption cross section on 3He and of both the unpolarised and polarised partial cross sections for the pion photoproduction channels γ 3He → πX and for the γ 3He → ppn channel, measured for the first time at MAMI, will be shown. They can also be found in [1].

  2. Nuclear georeactor origin of oceanic basalt 3He/4He, evidence, and implications

    PubMed Central

    Herndon, J. Marvin

    2003-01-01

    Nuclear georeactor numerical simulation results yield substantial 3He and 4He production and 3He/4He ratios relative to air (RA) that encompass the entire 2-SD (2σ) confidence level range of tabulated measured 3He/4He ratios of basalts from along the global spreading ridge system. Georeactor-produced 3He/4He ratios are related to the extent of actinide fuel consumption at time of production and are high near the end of the georeactor lifetime. Georeactor numerical simulation results and the observed high 3He/4He ratios measured in Icelandic and Hawaiian oceanic basalts indicate that the demise of the georeactor is approaching. Within the present level of uncertainty, one cannot say precisely when georeactor demise will occur, whether in the next century, in a million years, or in a billion years from now. PMID:12615991

  3. Electron bubbles and Weyl fermions in chiral superfluid 3He-A

    NASA Astrophysics Data System (ADS)

    Shevtsov, Oleksii; Sauls, J. A.

    2016-08-01

    Electrons embedded in liquid 3He form mesoscopic bubbles with large radii compared to the interatomic distance between 3He atoms, voids of Nbubble≈200 3He atoms, generating a negative ion with a large effective mass that scatters thermal excitations. Electron bubbles in chiral superfluid 3He-A also provide a local probe of the ground state. We develop a scattering theory of Bogoliubov quasiparticles by negative ions embedded in 3He-A that incorporates the broken symmetries of 3He-A , particularly broken symmetries under time reversal and mirror symmetry in a plane containing the chiral axis l ̂. Multiple scattering by the ion potential, combined with branch conversion scattering by the chiral order parameter, leads to a spectrum of Weyl fermions bound to the ion that support a mass current circulating the electron bubble—a mesoscopic realization of chiral edge currents in superfluid 3He-A films. A consequence is that electron bubbles embedded in 3He-A acquire angular momentum, L ≈-(Nbubble/2 ) ℏ l ̂ , inherited from the chiral ground state. We extend the scattering theory to calculate the forces on a moving electron bubble, both the Stokes drag and a transverse force, FW=e/c v ×BW , defined by an effective magnetic field, BW∝l ̂ , generated by the scattering of thermal quasiparticles off the spectrum of Weyl fermions bound to the moving ion. The transverse force is responsible for the anomalous Hall effect for electron bubbles driven by an electric field reported by the RIKEN group. Our results for the scattering cross section, drag, and transverse forces on moving ions are compared with experiments and shown to provide a quantitative understanding of the temperature dependence of the mobility and anomalous Hall angle for electron bubbles in normal and superfluid 3He-A . We also discuss our results in relation to earlier work on the theory of negative ions in superfluid 3He.

  4. 3He and BF 3 neutron detector pressure effect and model comparison

    NASA Astrophysics Data System (ADS)

    Lintereur, Azaree; Conlin, Kenneth; Ely, James; Erikson, Luke; Kouzes, Richard; Siciliano, Edward; Stromswold, David; Woodring, Mitchell

    2011-10-01

    Radiation detection systems for homeland security applications must possess the capability of detecting both gamma rays and neutrons. The radiation portal monitor systems that are currently deployed use a plastic scintillator for detecting gamma rays and 3He gas-filled proportional counters for detecting neutrons. Proportional counters filled with 3He are the preferred neutron detectors for use in radiation portal monitor systems because 3He has a large neutron cross-section, is relatively insensitive to gamma-rays, is neither toxic nor corrosive, can withstand extreme environments, and can be operated at a lower voltage than some of the alternative proportional counters. The amount of 3He required for homeland security and science applications has depleted the world supply and there is no longer enough available to fill the demand. Thus, alternative neutron detectors are being explored. Two possible temporary solutions that could be utilized while a more permanent solution is being identified are reducing the 3He pressure in the proportional counters and using boron trifluoride gas-filled proportional counters. Reducing the amount of 3He required in each of the proportional counters would decrease the rate at which 3He is being used; not enough to solve the shortage, but perhaps enough to increase the amount of time available to find a working replacement. Boron trifluoride is not appropriate for all situations as these detectors are less sensitive than 3He, boron trifluoride gas is corrosive, and a much higher voltage is required than what is used with 3He detectors. Measurements of the neutron detection efficiency of 3He and boron trifluoride as a function of tube pressure were made. The experimental results were also used to validate models of the radiation portal monitor systems.

  5. The {sup 150}Nd({sup 3}He,t) and {sup 150}Sm(t,{sup 3}He) reactions with applications to {beta}{beta} decay of {sup 150}Nd

    SciTech Connect

    Guess, C. J.; Brown, B. A.; Deaven, J. M.; Hitt, G. W.; Meharchand, R.; Zegers, R. G. T.; Adachi, T.; Fujita, H.; Hatanaka, K.; Hirota, K.; Ishikawa, D.; Matsubara, H.; Okamura, H.; Ong, H. J.; Suzuki, T.; Tamii, A.; Yosoi, M.; Zenihiro, J.; Akimune, H.; Algora, A.

    2011-06-15

    The {sup 150}Nd({sup 3}He,t) reaction at 140 MeV/u and {sup 150}Sm(t,{sup 3}He) reaction at 115 MeV/u were measured, populating excited states in {sup 150}Pm. The transitions studied populate intermediate states of importance for the (neutrinoless) {beta}{beta} decay of {sup 150}Nd to {sup 150}Sm. Monopole and dipole contributions to the measured excitation-energy spectra were extracted by using multipole decomposition analyses. The experimental results were compared with theoretical calculations obtained within the framework of the quasiparticle random-phase approximation, which is one of the main methods employed for estimating the half-life of the neutrinoless {beta}{beta} decay (0{nu}{beta}{beta}) of {sup 150}Nd. The present results thus provide useful information on the neutrino responses for evaluating the 0{nu}{beta}{beta} and 2{nu}{beta}{beta} matrix elements. The 2{nu}{beta}{beta} matrix element calculated from the Gamow-Teller transitions through the lowest 1{sup +} state in the intermediate nucleus is maximally about half that deduced from the half-life measured in 2{nu}{beta}{beta} direct counting experiments, and at least several transitions through 1{sup +} intermediate states in {sup 150}Pm are required to explain the 2{nu}{beta}{beta} half-life. Because Gamow-Teller transitions in the {sup 150}Sm(t,{sup 3}He) experiment are strongly Pauli blocked, the extraction of Gamow-Teller strengths was complicated by the excitation of the 2({h_bar}/2{pi}){omega}, {Delta}L=0, {Delta}S=1 isovector spin-flip giant monopole resonance (IVSGMR). However, the near absence of Gamow-Teller transition strength made it possible to cleanly identify this resonance, and the strength observed is consistent with the full exhaustion of the non-energy-weighted sum rule for the IVSGMR.

  6. T(T,2n)4He and 3He(3He,2p)4He: The Reaction Mechanism from Solar Energies to 10 MeV

    NASA Astrophysics Data System (ADS)

    Bacher, A. D.; Brune, C. R.; Sayre, D. B.; Hale, G. M.; Frenje, J. A.; Gatu Johnson, M.

    2016-03-01

    We have studied the energy dependence of the reaction mechanism of the T(t,2n)4He reaction at stellar energies and of its charge symmetric analog reaction 3He(3He,2p)4He at energies up 10 MeV. We find that the reaction mechanism changes dramatically over this energy range in part due to the interference of the two identical fermions in the three-body final state. This contribution is dedicated to the memory of Tom Tombrello, my Ph.D. advisor at Cal Tech, who died in 2014.

  7. Search for anomalous deuterons in the reaction /sup 3/He+C. -->. d+X at p3He = 10. 8 GeV/c

    SciTech Connect

    Ableev, V.G.; Vorob'ev, G.G.; Gasparyan, A.P.; Grigalashvili, N.S.; Dzhmukhadze, S.V.; Zaporozhets, S.A.; Nomofilov, A.A.; Piskunov, N.M.; Sitnik, I.M.; Strokovskii, E.A.

    1985-07-01

    The Alpha apparatus in a beam of 10.78-GeV/c /sup 3/He nuclei has been used to search for anomalous deuterons (demons) in the reaction /sup 3/He+C ..-->.. d+X. The deuteron yield was measured at angles theta< or approx. =20 mrad as a function of the target thickness, which varied from 0.6 to 70 cm. The data obtained exclude the production of demons in this reaction over a wide range of expected values of the cross sections for their production and interaction with matter. The technique used can be applied also to beams of relativistic nuclei in experiments to search for anomalons.

  8. Spinning filter separation system for oil spill clean-up operation

    SciTech Connect

    Wehrle, J.; Fischer, E.C.; Kenney, W.P.; Korczynski, J.F.; Gracik, T.D.

    1996-09-26

    According to current technology, effective clean up of oil spills from the surface of ocean water is performed by an oil sweeper vessel within which oil contaminated water is collected for transport to remotely located on-shore equipment within which oil separation and disposal is performed. The processing of large quantities of oil polluted ocean water is accordingly time consuming as well as costly. It is therefore an important object of the present invention to provide a less costly oil spill clean up system involving more rapid processing of large quantities of oil polluted ocean water. In accordance with the present invention, oil polluted ocean water is processed at an oil spill location by continuous separation during pressurized flow of the water through at least two separator devices within which successive reduction in oil concentration is effected with respect to a separated portion of the water by filtered flow through porous membrane walls to correspondingly increase the oil concentration within the other remaining portion of water being processed. The first portion of the processed water when sufficiently reduced in oil concentration is discharged for return to the oil spill location, while the remaining portion is collected until a sufficient level of oil concentration therein is achieved to permit disposal thereof by burning at the oil spill site.

  9. The cosmological density of baryons from observations of 3He+ in the Milky Way.

    PubMed

    Bania, T M; Rood, Robert T; Balser, Dana S

    2002-01-01

    Primordial nucleosynthesis after the Big Bang can be constrained by the abundances of the light elements and isotopes 2H, 3He, 4He and 7Li (ref. 1). The standard theory of stellar evolution predicts that 3He is also produced by solar-type stars, so its abundance is of interest not only for cosmology, but also for understanding stellar evolution and the chemical evolution of the Galaxy. The 3He abundance in star-forming (H II) regions agrees with the present value for the local interstellar medium, but seems to be incompatible with the stellar production rates inferred from observations of planetary nebulae, which provide a direct test of stellar evolution theory. Here we develop our earlier observations, which, when combined with recent theoretical developments in our understanding of light-element synthesis and destruction in stars, allow us to determine an upper limit for the primordial abundance of 3He relative to hydrogen: 3He/H = (1.1 +/- 0.2) x 10(-5). The primordial density of all baryons determined from the 3He data is in excellent agreement with the densities calculated from other cosmological probes. The previous conflict is resolved because most solar-mass stars do not produce enough 3He to enrich the interstellar medium significantly. PMID:11780112

  10. Anomalous yield reduction in direct-drive DT implosions due to 3He addition

    SciTech Connect

    Herrmann, Hans W; Langenbrunner, James R; Mack, Joseph M; Cooley, James H; Wilson, Douglas C; Evans, Scott C; Sedillo, Tom J; Kyrala, George A; Caldwell, Stephen E; Young, Carlton A; Nobile, Arthur; Wermer, Joseph R; Paglieri, Stephen N; Mcevoy, Aaron M; Kim, Yong Ho; Batha, Steven H; Horsfield, Colin J; Drew, Dave; Garbett, Warren; Rubery, Michael; Glebov, Vladimir Yu; Roberts, Samuel; Frenje, Johan A

    2008-01-01

    Glass capsules were imploded in direct drive on the OMEGA laser [T. R. Boehly et aI., Opt. Commun. 133, 495, 1997] to look for anomalous degradation in deuterium/tritium (DT) yield (i.e., beyond what is predicted) and changes in reaction history with {sup 3}He addition. Such anomalies have previously been reported for D/{sup 3}He plasmas, but had not yet been investigated for DT/{sup 3}He. Anomalies such as these provide fertile ground for furthering our physics understanding of ICF implosions and capsule performance. A relatively short laser pulse (600 ps) was used to provide some degree of temporal separation between shock and compression yield components for analysis. Anomalous degradation in the compression component of yield was observed, consistent with the 'factor of two' degradation previously reported by MIT at a 50% {sup 3}He atom fraction in D{sub 2} using plastic capsules [Rygg et aI., Phys. Plasmas 13, 052702 (2006)]. However, clean calculations (i.e., no fuel-shell mixing) predict the shock component of yield quite well, contrary to the result reported by MIT, but consistent with LANL results in D{sub 2}/{sup 3}He [Wilson, et aI., lml Phys: Conf Series 112, 022015 (2008)]. X-ray imaging suggests less-than-predicted compression ofcapsules containing {sup 3}He. Leading candidate explanations are poorly understood Equation-of-State (EOS) for gas mixtures, and unanticipated particle pressure variation with increasing {sup 3}He addition.

  11. Third sound and stability of 3He-4He mixture films

    SciTech Connect

    Anderson, R. H.; Krotscheck, E.; Miller, M. D.

    2006-09-07

    We study third sound and the interaction between 3He adatoms in two thin 3He-4He mixture films from a first-principles, microscopic theory. Utilizing the variational, hypernetted-chain Euler-Lagrange (HNC-EL) theory as applied to inhomogeneous boson systems, we calculate chemical potentials for both the 4He superfluid film and the physisorbed 3He. Numerical density derivatives of the chemical potentials lead to the sought-after third sound speeds that clearly reflect a layered structure of at least seven oscillations. In this paper, we report third sound on model substrates: Nuclepore, and sodium. We find that the effect of the 3He depends sensitively on the particular 4He film coverage. Our most important result is that, with the addition of 3He, the third sound speed can either increase or decrease. In fact, in some regimes, the added 3He destabilizes the film and can drive ''layering transitions'', leading to fairly complicated geometric structures of the film in which the outermost layer is predicted to consist of phase-separated regions of 3He and 4He.

  12. Multi-spacecraft observations of recurrent {sup 3}He-rich solar energetic particles

    SciTech Connect

    Bučík, R.; Innes, D. E.; Mall, U.; Korth, A.; Mason, G. M.; Gómez-Herrero, R.

    2014-05-01

    We study the origin of {sup 3}He-rich solar energetic particles (<1 MeV nucleon{sup –1}) that are observed consecutively on STEREO-B, Advanced Composition Explorer (ACE), and STEREO-A spacecraft when they are separated in heliolongitude by more than 90°. The {sup 3}He-rich period on STEREO-B and STEREO-A commences on 2011 July 1 and 2011 July 16, respectively. The ACE {sup 3}He-rich period consists of two sub-events starting on 2011 July 7 and 2011 July 9. We associate the STEREO-B July 1 and ACE July 7 {sup 3}He-rich events with the same sizeable active region (AR) producing X-ray flares accompanied by prompt electron events, when it was near the west solar limb as seen from the respective spacecraft. The ACE July 9 and STEREO-A July 16 events were dispersionless with enormous {sup 3}He enrichment, lacking solar energetic electrons and occurring in corotating interaction regions. We associate these events with a small, recently emerged AR near the border of a low-latitude coronal hole that produced numerous jet-like emissions temporally correlated with type III radio bursts. For the first time we present observations of (1) solar regions with long-lasting conditions for {sup 3}He acceleration and (2) solar energetic {sup 3}He that is temporarily confined/re-accelerated in interplanetary space.

  13. Cosmogenic 3He in terrestrial rocks: The summit lavas of Maui

    PubMed Central

    Craig, H.; Poreda, R. J.

    1986-01-01

    We have identified terrestrial cosmic rayproduced 3He in three lava flows on the crest of Haleakala Volcano on Maui, 3 km above sea level, and ≈0.5 million years old. Although these lavas, like all oceanic basalts, contain primordial 3He from the mantle, the “cosmogenic” component (3HeC) can be identified unambiguously because it is extractable only by high-temperature vacuum fusion. In contrast, a large fraction of the mantle helium resides in fluid inclusions and can be extracted by vacuum crushing, leaving a residual component with 3He/4He ratios as high as 75× those in the atmosphere, which can be liberated by melting the crushed grains. Cosmogenic 3He is present in both olivines and clinopyroxenes at 0.8-1.2 × 10-12 ml(STP)/g and constitutes 75% ± 5% of the total 3He present. The observed 3HeC levels require a cosmic ray exposure age of only some 64,000 years, much less than the actual age of the lavas, if there is no erosion. Using a model that includes effects of uplift or submergence as well as erosion, we calculate an apparent “erosion rate” of the order of 8.5 m/106 years for the western rim of the summit crater, as an example of the application of measurements of cosmogenic rare gases to terrestrial geological problems. PMID:16593671

  14. Polarized {sup 3}He{sup −} ion source with hyperfine state selection

    SciTech Connect

    Dudnikov, V.; Morozov, V.; Dudnikov, A.

    2015-04-08

    High beam polarization is essential to the scientific productivity of a collider. Polarized {sup 3}He ions are an essential part of the nuclear physics programs at existing and future ion-ion and electron-ion colliders such as BNL's RHIC and eRHIC and JLab's ELIC. Ion sources with performance exceeding that achieved today are a key requirement for the development of these next generation high-luminosity high-polarization colliders. The development of high-intensity high-brightness arc-discharge ion sources at the Budker Institute of Nuclear Physics (BINP) has opened up an opportunity for realization of a new type of a polarized {sup 3}He{sup −} ion source. This report discusses a polarized {sup 3}He{sup −} ion source based on the large difference of extra-electron auto-detachment lifetimes of the different {sup 3}He{sup −} ion hyperfine states. The highest momentum state of 5/2 has the largest lifetime of τ ∼ 350 µs while the lower momentum states have lifetimes of τ ~ 10 µs. By producing {sup 3}He{sup −} ion beam composed of only the |5/2, ±5/2> hyperfine states and then quenching one of the states by an RF resonant field, {sup 3}He{sup −} beam polarization of 90% can be achieved. Such a method of polarized {sup 3}He{sup −} production has been considered before; however, due to low intensities of the He{sup +} ion sources existing at that time, it was not possible to produce any interesting intensity of polarized {sup 3}He{sup −} ions. The high-brightness arc-discharge ion source developed at BINP can produce a high-brightness {sup 3}He{sup +} beam with an intensity of up to 2 A allowing for selection of up to ∼1-4 mA of {sup 3}He{sup −} ions with ∼90% polarization. The high gas efficiency of an arc-discharge source is important due to the high cost of {sup 3}He gas. Some features of such a PIS as well as prototype designs are considered. An integrated {sup 3}He{sup −} ion source design providing high beam polarization could be

  15. A polarized internal sup 3 He target using optical pumping of metastable atoms

    SciTech Connect

    McKeown, R.D.; Milner, R.G.; Woodward, C.E. )

    1989-05-05

    The design of a polarized internal {sup 3}He target for use in storage rings based on optical pumping of metastables is discussed. The target employs an infrared laser to polarize {sup 3}He atoms in a pyrex cell which is connected by a capillary to a windowless cell through which the stored beam passes. Using this technique it should be possible construct targets of 50% polarized {sup 3}He targets of thickness 10{sup 16} cm{sup {minus}2}. Small holding fields ({similar to}10 gauss) and resistance to beam-induced depolarization are desirable features of this target in a storage ring environment.

  16. Experimental investigation and theoretical calculation for 3He induced nuclear reactions on vanadium

    NASA Astrophysics Data System (ADS)

    Ali, B. M.; Al-Abyad, M.; Seddik, U.; El-Kameesy, S. U.; Ditrói, F.; Takács, S.; Tárkányi, F.

    2016-04-01

    Using stacked-foil activation technique and gamma-ray spectrometry, excitation functions for 3He induced nuclear reactions on natV were measured. Cross-sections for natV(3He, xn)52m,gMn and natV(3He, pxn)51Cr nuclear reactions were measured up to 27 MeV utilizing the MGC-20E cyclotron of ATOMKI. The measurements establish for the first time consistent excitation curves. Comparisons with results for values derived from different theoretical codes were included. Integral yield were calculated.

  17. Triple oxygen isotopic composition of the high-3He/4He mantle

    NASA Astrophysics Data System (ADS)

    Starkey, N. A.; Jackson, C. R. M.; Greenwood, R. C.; Parman, S.; Franchi, I. A.; Jackson, M.; Fitton, J. G.; Stuart, F. M.; Kurz, M.; Larsen, L. M.

    2016-03-01

    Measurements of Xe isotope ratios in ocean island basalts (OIB) suggest that Earth's mantle accreted heterogeneously, and that compositional remnants of accretion are sampled by modern, high-3He/4He OIB associated with the Icelandic and Samoan plumes. If so, the high-3He/4He source may also have a distinct oxygen isotopic composition from the rest of the mantle. Here, we test if the major elements of the high-3He/4He source preserve any evidence of heterogeneous accretion using measurements of three oxygen isotopes on olivine from a variety of high-3He/4He OIB locations. To high precision, the Δ17O value of high-3He/4He olivines from Hawaii, Pitcairn, Baffin Island and Samoa, are indistinguishable from bulk mantle olivine (Δ17OBulk Mantle - Δ17OHigh 3He/4He olivine = -0.002 ± 0.004 (2 × SEM)‰). Thus, there is no resolvable oxygen isotope evidence for heterogeneous accretion in the high-3He/4He source. Modelling of mixing processes indicates that if an early-forming, oxygen-isotope distinct mantle did exist, either the anomaly was extremely small, or the anomaly was homogenised away by later mantle convection. The δ18O values of olivine with the highest 3He/4He ratios from a variety of OIB locations have a relatively uniform composition (∼5‰). This composition is intermediate to values associated with the depleted MORB mantle and the average mantle. Similarly, δ18O values of olivine from high-3He/4He OIB correlate with radiogenic isotope ratios of He, Sr, and Nd. Combined, this suggests that magmatic oxygen is sourced from the same mantle as other, more incompatible elements and that the intermediate δ18O value is a feature of the high-3He/4He mantle source. The processes responsible for the δ18O signature of high-3He/4He mantle are not certain, but δ18O-87Sr/86Sr correlations indicate that it may be connected to a predominance of a HIMU-like (high U/Pb) component or other moderate δ18O components recycled into the high-3He/4He source.

  18. Operations and performance of the PACS instrument 3He sorption cooler on board of the Herschel space observatory

    NASA Astrophysics Data System (ADS)

    Sauvage, M.; Okumura, K.; Klaas, U.; Müller, Th.; Moór, A.; Poglitsch, A.; Feuchtgruber, H.; Duband, L.

    2014-07-01

    A 3He sorption cooler produced the operational temperature of 285 mK for the bolometer arrays of the Photodetector Array Camera and Spectrometer (PACS) instrument of the Herschel Space Observatory. This cooler provided a stable hold time between 60 and 73 h, depending on the operational conditions of the instrument. The respective hold time could be determined by a simple functional relation established early on in the mission and reliably applied by the scientific mission planning for the entire mission. After exhaustion of the liquid 3He due to the heat input by the detector arrays, the cooler was recycled for the next operational period following a well established automatic procedure. We give an overview of the cooler operations and performance over the entire mission and distinguishing in-betweenthe start conditions for the cooler recycling and the two main modes of PACS photometer operations. As a spin-off, the cooler recycling temperature effects on the Herschel cryostat 4He bath were utilized as an alternative method to dedicated Direct Liquid Helium Content Measurements in determining the lifetime of the liquid Helium coolant.

  19. Kaonic 3He and 4He X-ray measurements in SIDDHARTA

    NASA Astrophysics Data System (ADS)

    Ishiwatari, Tomoichi; Bazzi, M.; Beer, G.; Berucci, C.; Bombelli, L.; Bragadireanu, A. M.; Cargnelli, M.; Clozza, A.; Corradi, G.; Curceanu (Petrascu), C.; d'Uffizi, A.; Fiorini, C.; Ghio, F.; Girolami, B.; Guaraldo, C.; Hayano, R. S.; Iliescu, M.; Iwasaki, M.; Kienle, P.; Levi Sandri, P.; Lucherini, V.; Marton, J.; Okada, S.; Pietreanu, D.; Piscicchia, K.; Poli Lener, M.; Ponta, T.; Quaglia, R.; Rizzo, A.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Tudorache, A.; Tudorache, V.; Vazquez Doce, O.; Widmann, E.; Wünschek, B.; Zmeskal, J.

    2012-05-01

    The SIDDHARTA experiment measured the kaonic 3He and 4He 3 d →2 p X-ray transitions using gaseous targets for the first time. The strong-interaction shift both of the kaonic 3He and 4He 2 p states was determined with a precision of a few eV. The shift of kaonic 4He is much smaller than the values obtained in the experiments performed in 70's and 80's, while it is consistent with the recent result of the KEK E570 experiment, as well as the theoretical calculated values. Therefore, the problem on kaonic helium (the "kaonic helium puzzle") was definitely solved. The first observation of the kaonic 3He X-rays was also achieved in the SIDDHARTA experiment. The shift both of kaonic 3He and 4He was found to be as small as a few eV.

  20. Kaonic 3He and 4He X-ray measurements in SIDDHARTA

    NASA Astrophysics Data System (ADS)

    Ishiwatari, Tomoichi; Bazzi, M.; Beer, G.; Berucci, C.; Bombelli, L.; Bragadireanu, A. M.; Cargnelli, M.; Clozza, A.; Corradi, G.; Curceanu (Petrascu), C.; d'Uffizi, A.; Fiorini, C.; Ghio, F.; Girolami, B.; Guaraldo, C.; Hayano, R. S.; Iliescu, M.; Iwasaki, M.; Kienle, P.; Levi Sandri, P.; Lucherini, V.; Marton, J.; Okada, S.; Pietreanu, D.; Piscicchia, K.; Poli Lener, M.; Ponta, T.; Quaglia, R.; Rizzo, A.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Tudorache, A.; Tudorache, V.; Vazquez Doce, O.; Widmann, E.; Wünschek, B.; Zmeskal, J.

    The SIDDHARTA experiment measured the kaonic 3He and 4He 3d →2p X-ray transitions using gaseous targets for the first time. The strong-interaction shift both of the kaonic 3He and 4He 2p states was determined with a precision of a few eV. The shift of kaonic 4He is much smaller than the values obtained in the experiments performed in 70's and 80's, while it is consistent with the recent result of the KEK E570 experiment, as well as the theoretical calculated values. Therefore, the problem on kaonic helium (the "kaonic helium puzzle") was definitely solved. The first observation of the kaonic 3He X-rays was also achieved in the SIDDHARTA experiment. The shift both of kaonic 3He and 4He was found to be as small as a few eV.

  1. Beating Analysis of Shubnikov de Haas Oscillation in In0.53Ga0.47As Double Quantum Well toward Spin Filter Applications

    NASA Astrophysics Data System (ADS)

    Koga, Takaaki; Matsuura, Toru; Faniel, Sébastien; Souma, Satofumi; Mineshige, Shunsuke; Sekine, Yoshiaki; Sugiyama, Hiroki

    We recently determined the values of intrinsic spin-orbit (SO) parameters for In0.52Al0.48As/In0.53Ga0.47As(10nm)/In0.52Al0.48As (InGaAs/InAlAs) quantum wells (QW), lattice-matched to (001) InP, from the weak localization/antilocalization analysis of the low-temperature magneto-conductivity measurements [1]. We have then studied the subband energy spectra for the InGaAs/InAlAs double QW system from beatings in the Shubnikov de Haas (SdH) oscillations. The basic properties obtained here for the double QW system provides useful information for realizing nonmagnetic spin-filter devices based on the spin-orbit interaction [2].

  2. The Triple Oxygen Isotopic Composition of High 3He/4He Mantle

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Parman, S. W.; Starkey, N.; Greenwood, R.; Franchi, I.; Jackson, M. G.; Fitton, J. G.; Stewart, F. M.; Larsen, L. M.

    2015-12-01

    Measurements of Xe isotope ratios in ocean island basalts (OIB) suggest that Earth's mantle accreted heterogeneously, and that compositional remnants of accretion are sampled by modern, high-3He/4He OIB associated with the Icelandic and Samoan plumes [1]. If so, the high-3He/4He source may also have a distinct oxygen isotopic composition from the rest of the mantle. Here, we test if the major elements of the high-3He/4He source preserve any evidence of heterogeneous accretion using measurements of three oxygen isotopes on olivine from a variety of high-3He/4He OIB locations. To high precision, the ∆17O value of high-3He/4He olivines from Hawaii, Pitcairn, Baffin Island and Samoa, are indistinguishable from bulk mantle olivine (Δ17OBulk Mantle - Δ17OHigh 3He/4He olivine = -0.002 ± 0.004 (2 x SEM) ‰). Thus, there is no resolvable oxygen isotope evidence for heterogeneous accretion in the high-3He/4He source. Modelling of mixing processes indicates that if an early-forming, oxygen-isotope distinct mantle did exist, either the anomaly was extremely small, or the anomaly was homogenised away by later mantle convection. The δ18O values of olivine with the highest 3He/4He ratios from a variety of OIB locations have a relatively uniform composition (~5 ‰). This composition is intermediate to values associated with the depleted MORB mantle and the average mantle. Similarly, δ18O values of olivine from high-3He/4He OIB correlate with radiogenic isotope ratios of He, Sr, and Nd. Combined, this suggests that oxygen remains coupled to the more incompatible elements during melt production and migration and that the intermediate δ18O value is a feature of the mantle source. The processes responsible for the δ18O signature of high-3He/4He mantle are not certain, but δ18O-87Sr/86Sr correlations indicate that it may be connected to a predominance of a HIMU-like (high U/Pb) component or other moderate δ18O components recycled into the high-3He/4He source. [1] S

  3. Sound velocity measurement of nuclear-ordered U2D2 solid 3He along the melting curve

    NASA Astrophysics Data System (ADS)

    Nomura, R.; Suzuki, M.; Yamaguchi, M.; Sasaki, Y.; Mizusaki, T.

    2000-05-01

    The sound velocity of a single-domain 3He crystal was measured in the nuclear-ordered low-field phase and the paramagnetic phase along the melting curve, using 10.98 MHz longitudinal sound. The temperature dependence of the sound velocity along the melting curve was explained by a nuclear spin contribution and the molar volume change along the melting curve. By comparing the measured velocity with thermodynamic quantities, we extracted the Grüneizen constant for the exchange energy. The anisotropy of the velocity in the ordered phase was investigated for three samples and was found to be smaller than 2×10 -5 in Δ v/ v. The attenuation coefficient of the sound was much smaller than 0.2 cm-1.

  4. The mean ionic charge of silicon in 3HE-rich solar flares

    NASA Technical Reports Server (NTRS)

    Luhn, A.; Klecker, B.; Hovestadt, E.; Moebius, E.

    1985-01-01

    Mean ionic charge of iron in 3He-rich solar flares and the average mean charge of Silicon for 23 #He-rich periods during the time interval from September 1978 to October 1979 were determined. It is indicated that the value of the mean charge state of Silicon is higher than the normal flare average by approximately 3 units and in perticular it is higher then the value predicted by resonant heating models for 3He-rich solar flares.

  5. Distal airways in humans: dynamic hyperpolarized 3He MR imaging--feasibility

    NASA Technical Reports Server (NTRS)

    Tooker, Angela C.; Hong, Kwan Soo; McKinstry, Erin L.; Costello, Philip; Jolesz, Ferenc A.; Albert, Mitchell S.

    2003-01-01

    Dynamic hyperpolarized helium 3 (3He) magnetic resonance (MR) imaging of the human airways is achieved by using a fast gradient-echo pulse sequence during inhalation. The resulting dynamic images show differential contrast enhancement of both distal airways and the lung periphery, unlike static hyperpolarized 3He MR images on which only the lung periphery is seen. With this technique, up to seventh-generation airway branching can be visualized. Copyright RSNA, 2003.

  6. A review of sup 3 He resources and acquisition for use as fusion fuel

    SciTech Connect

    Wittenberg, L.J.; Camerson, E.N.; Kulcinski, G.L.; Ott, S.H.; Santarius, J.F.; Sviatoslavsky, G.I.; Sviatoslavsky, I.N.; Thompson, H.E. . Fusion Technology Inst.)

    1992-07-01

    This paper reports that a combination of man-made and natural resources on earth could provide sufficient {sup 3}He fuel for the technological development of D-{sup 3}He fusion reactors. Helium exists in natural gas wells; however, at the current rate of natural gas usage, this resource would provide {lt}5 kg/yr of {sup 3}He. The radioactive decay of {sup 3}H produced in fission production reactors could yield 110 kg of {sup 3}He by the year 2000 if it were retained. Apparently, a large amount of {sup 3}He exists within the earth's mantle, but it is inaccessible. A significant quantity of {sup 3}He, which could be imported to supply a fusion power industry on earth for hundreds of years, exists on the moon. The solar wind has deposited {gt}1 million tonnes of {sup 3}He in the fine regolith that covers the surface of the moon. The presence of this solar wind gas was confirmed by analyses of the lunar regolith samples brought to earth. A strong correlation is noted between the helium retained and the TiO{sub 2} content of the regolith; consequently, remote-sensing data showing high-titanium-bearing soils in the lunar maria areas have been used to locate potentially rich sites for helium extraction. Surface photographs of Mare Tranquillitatis have shown that nearly 50% of this mare may be minable and capable of supplying {approximately}7100 tonnes of {sup 3}He. A mobile mining vehicle is proposed for use in the excavation of the soil and the release of the helium and other solar wind gases. The evolved gases would be purified by a combination of permeators and cryogenic techniques to provide a rich resource of H{sub 2}, helium, CO{sub 2}, H{sub 2}O, and N{sub 2}, followed by helium isotopic separation systems.

  7. Examining Particle Transport in Multi-Spacecraft 3He-Rich SEP Events

    NASA Astrophysics Data System (ADS)

    Cohen, Christina; Giacalone, Joe; Wiedenbeck, Mark E.; Mason, Glenn

    2015-04-01

    One of the surprising outcomes of recent multi-spacecraft studies of solar energetic particle (SEP) events is that small 3He-rich events can have large longitudinal spans. Although their solar source region is typically quite small, individual 3He-rich SEP events have been detected by near-1AU spacecraft separated by as much as 136 degrees. Although bundles of magnetic field lines can expand from small areas (5-10 degrees) at the photosphere to larger (~60 degrees) regions at 2.5 RS, this is not sufficient to explain the wide 3He-rich events observed by well-separated spacecraft. One possible explanation of these events involves a combination of particle diffusion in the inner heliosphere and field line co-rotation with the Sun. We have examined the onsets of the elevated 3He intensities at ACE and both STEREO spacecraft for several wide 3He-rich SEP events. The timing of these onsets has been compared to that predicted by a diffusive transport model for particle propagation. These results and their implications for the conditions conducive to creating wide 3He-rich SEP events are discussed.

  8. Pomeranchuk cell for hyperpolarized 3He based on the brute force method

    NASA Astrophysics Data System (ADS)

    Makino, Seiji; Tanaka, Masayoshi; Ueda, Kunihiro; Fujiwara, Mamoru; Fujimura, Hisako; Yosoi, Masaru; Ohta, Takeshi; Frossati, Giorgio; de Waard, Arlette; Rouille, Gerard

    2014-09-01

    MRI (Magnetic Resonance Imaging) has been used for the medical diagnosis as a radiation-free imaging equipment. Since the proton has been mainly used for medical MRI, usefulness has been rather restrictive. As an example for expanding the range of applicability, MRI with hyperpolarized 3He gas has been used for the lung disease. Here, ``hyperpolarized'' means ``polarized higher than the thermal equilibrium polarization.'' For producing a large amount of hyperpolarized 3He gas at a time, we have been developing a hyperpolarization technique based on the brute force method which uses an ultralow temperature of a few mK and a strong magnetic field around 17 T in combination with the principle of the Pomeranchuk cooling. The Pomeranchuk cell made with non-metallic materials of small heat capacity is attached to the 3He/4He dilution refrigerator using a sintered silver allowing large heat conduction. After the sensors to monitor the temperature and pressure of 3He are calibrated and the Pomeranchuk cell is constructed, the system is tested. Then, the solidification of 3He and the measurement of NMR (Nuclear Magnetic Resonance) signals of 3He under the magnetic field of 17 T are carried out. The current status is reported in this talk.

  9. Thermal resistance between liquid /sup 3/He and copper potassium tutton salt

    SciTech Connect

    Fujii, Y.; Shigi, T.

    1987-01-01

    The thermal resistance between liquid /sup 3/He and copper potassium tutton salt (CPS) has been measured through its magnetic ordering temperature (T/sub c/ = 29.6 mK). The thermal resistance R for pure /sup 3/He has a broad minimum near 60 mK and increases continuously through T/sub c/ with decreasing temperature, except for a dip at T/sub c/. Below T/sub c/, R is proportional to T/sup -1.5/. Effects of /sup 4/He coating have been studied by stepwise addition of /sup 4/Me into liquid /sup 3/He. The thermal resistance increased drastically for the liquid containing 150 ppm/sup 4/Me and more for 95% /sup 4/He. By sudden depressurization of the liquid /sup 3/He containing 480 ppm /sup 4/He, a considerable decrease of R was observed. Since R for pure /sup 3/He was much smaller than the calculated Kapitza resistance, the present experimental results indicate the existence of surface magnetic coupling between liquid /sup 3/He and CPS.

  10. Tritium/3He measurements in young groundwater: Progress in applications to complex hydrogeological systems

    USGS Publications Warehouse

    Schlosser, P.; Shapiro, S.D.; Stute, M.; Plummer, N.

    2000-01-01

    Tritium/3He dating has been applied to many problems in groundwater hydrology including, for example, determination of circulation patterns, mean residence times, recharge rates, or bank infiltration. Here, we discuss recent progress in the application of the tritium/3He dating method to sites with complex hydrogeological settings. Specifically, we report on tritium/3He dating at sites with (a) river infiltration into the basaltic fractured rock aquifer of the Eastern Snake River Plain, and (b) river infiltration through sinkholes into the karstic limestone Upper Floridian aquifer near Valdosta, Georgia.Tritium/3He dating has been applied to many problems in groundwater hydrology including, for example, determination of circulation patterns, mean residence times, recharge rates, or bank infiltration. Here, we discuss recent progress in the application of the tritium/3He dating method to sites with complex hydrogeological settings. Specifically, we report on tritium/3He dating at sites with (a) river infiltration into the basaltic fractured rock aquifer of the Eastern Snake River Plain, and (b) river infiltration through sinkholes into the karstic limestone Upper Floridian aquifer near Valdosta, Georgia.

  11. Terrestrial cosmogenic 3He: where are we 30 years after its discovery?

    NASA Astrophysics Data System (ADS)

    Blard, Pierre-Henri; Pik, Raphaël; Farley, Kenneth A.; Lavé, Jérôme; Marrocchi, Yves

    2016-04-01

    It is now 30 years since cosmogenic 3He has been detected for the first time in a terrestrial sample (Kurz, 1986). 3He is now a widely used geochemical tool in many fields of Earth sciences: volcanology, tectonics, paleoclimatology. 3He has the advantage to have a high "production rate" to "detection limit" ratio, allowing surfaces as young as hundred of years to be dated. Although its nuclear stability implies several limitations, it moreover represents a useful alternative to 10Be in mafic environments. This contribution is a review of the progresses that have been accomplished since this discovery, and discuss strategies to improve both the accuracy and the precision of this geochronometer. 1) Measurement of cosmogenic 3He Correction of magmatic 3He. To estimate the non-cosmogenic magmatic 3He, Kurz (1986) invented a two steps method involving crushing of phenocrysts (to analyze the isotopic ratio of the magmatic component), followed by a subsequent melting of the sample, to extract the remaining components, including the cosmogenic 3He: 3Hec = 3Hemelt ‑4Hemelt x (3He/4He)magmatic (1) Several studies suggested that the preliminary crushing may induce a loss of cosmogenic 3He (Hilton et al., 1993; Yokochi et al., 2005; Blard et al., 2006), implying an underestimate of the cosmogenic 3He measurement. However, subsequent work did not replicate these observations (Blard et al., 2008; Goerhing et al., 2010), suggesting an influence of the used apparatus. An isochron method (by directly melting several phenocrysts aliquots) is an alternative to avoid the preliminary crushing step (Blard and Pik, 2008). Atmospheric contamination. Protin et al. (in press) provides robust evidences for a large and irreversible contamination of atmospheric helium on silicate surfaces. This unexpected behavior may reconcile the contrasted observations about the amplitude of crushing loss. This undesirable atmospheric contamination is negligible if grain fractions smaller than 150 mm are

  12. Modeling 3H-3He Gas-Liquid Phase Transport for Interpretation of Groundwater Age

    NASA Astrophysics Data System (ADS)

    Carle, S. F.; Esser, B.; Moran, J. E.

    2009-12-01

    California’s Groundwater Ambient Monitoring and Assessment (GAMA) Program has measured many hundreds of tritium (3H) and helium-3 (3He) concentrations in well water samples to derive estimates of groundwater age at production and monitoring wells in California basins. However, a 3H-3He age differs from an ideal groundwater age tracer in several respects: (1) the radioactive decay of 3H results in the accumulation of 3He being first-order with respect to 3H activity (versus a zero-order age-mass accumulation process for an ideal tracer), (2) surface concentrations of 3H as measured in precipitation over the last several decades have not been uniform, and (3) the 3H-3He “clock” begins at the water table and not at the ground surface where 3H source measurements are made. To better understand how these non-idealities affect interpretation of 3H-3He apparent groundwater age, we are modeling coupled gas-liquid phase flow and 3H-3He transport including processes of radiogenic decay, phase equilibrium, and molecular diffusion for water, air, 3H, and 3He components continuously through the vadose zone and saturated zone. Assessment of coupled liquid-gas phase processes enables consideration of 3H-3He residence time and dispersion within the vadose zone, including partitioning of tritiogenic 3He to the gas phase and subsequent diffusion into the atmosphere. The coupled gas-liquid phase modeling framework provides direct means to compare apparent 3H-3He age to ideal mean or advective groundwater ages for the same groundwater flow conditions. Examples are given for common groundwater flow systems involving areal recharge, discharge to streams or long-screened wells, and aquifer system heterogeneity. The Groundwater Ambient Monitoring and Assessment program is sponsored by the California State Water Resources Control Board and carried out in cooperation with the U.S. Geological Survey. This work was performed under the auspices of the U.S. Department of Energy by

  13. Optimization of the polarized Klein tunneling currents in a sub-lattice: pseudo-spin filters and latticetronics in graphene ribbons.

    PubMed

    López, Luis I A; Yaro, Simeón Moisés; Champi, A; Ujevic, Sebastian; Mendoza, Michel

    2014-02-12

    We found that with an increase of the potential barrier applied to metallic graphene ribbons, the Klein tunneling current decreases until it is totally destroyed and the pseudo-spin polarization increases until it reaches its maximum value when the current is zero. This inverse relation disfavors the generation of polarized currents in a sub-lattice. In this work we discuss the pseudo-spin control (polarization and inversion) of the Klein tunneling currents, as well as the optimization of these polarized currents in a sub-lattice, using potential barriers in metallic graphene ribbons. Using density of states maps, conductance results, and pseudo-spin polarization information (all of them as a function of the energy V and width of the barrier L), we found (V, L) intervals in which the polarized currents in a given sub-lattice are maximized. We also built parallel and series configurations with these barriers in order to further optimize the polarized currents. A systematic study of these maps and barrier configurations shows that the parallel configurations are good candidates for optimization of the polarized tunneling currents through the sub-lattice. Furthermore, we discuss the possibility of using an electrostatic potential as (i) a pseudo-spin filter or (ii) a pseudo-spin inversion manipulator, i.e. a possible latticetronic of electronic currents through metallic graphene ribbons. The results of this work can be extended to graphene nanostructures. PMID:24441476

  14. Photodisintegration of /sup 3/H and /sup 3/He. [Threshold to 25 MeV

    SciTech Connect

    Faul, D.D.

    1980-09-01

    The photoneutron cross sections for /sup 3/H and /sup 3/He have been measured from threshold to approx. 25 MeV with monoenergetic photons from the annihilation in flight of fast positrons at the LLL Electron-Positron Linear Accelerator facility. These reactions include the two-body breakup of /sup 3/H and the three-body breakup of both /sup 3/H and /sup 3/He; these measurements for /sup 3/H are the first to span the energy region across the peaks of the cross sections. An efficient BF/sub 3/-tube-and-paraffin neutron detector and high-pressure gaseous samples of several moles each (the activity of the /sup 3/H sample was approx. 200,000 Ci) were employed in these measurements. Measurements on /sup 16/O and /sup 2/H also were performed to verify the absolute cross-section scale. The results, when compared with each other and with results for the two-body breakup cross section for /sup 3/He from the literature, show that the two-body breakup cross sections for /sup 3/H and /sup 3/He have nearly the same shape, but the one for /sup 3/He lies lower in magnitude; the three-body breakup cross section for /sup 3/He lies higher in magnitude and is broader in the peak region and also rises less sharply from threshold than that for /sup 3/H; and these measured differences between the cross sections for the breakup modes largely compensate in their sum, so that the total photon absorption cross sections for /sup 3/H and /sup 3/He are nearly the same in both size and shape at energies near and above their peaks. Theoretical results from the literature disagree with the experimental results to a certain extent over the entire photon-energy region for which the photoneutron cross sections were measured. 50 figures, 7 tables.

  15. A new method for determining the 3He/4He ratio in the local interstellar medium

    NASA Astrophysics Data System (ADS)

    Lemoine, M.; Vidal-Madjar, A.; Ferlet, R.

    1993-06-01

    We propose here an original method for estimating the 3He/4 Heratio in the local diffuse interstellar medium at a low cost from an observational point of view. The main idea is to measure the shift in radial velocity of the 4He λ537Å and λ584Å lines due to the presence of 3He in the red wing of these lines, and to compare the observed shift to the shifts obtained through numerical simulations for different 3He/4He ratios. We performed such simulations in order to reveal the efficiency of this method, using typical astrophysical conditions and instrumental parameters corresponding to the Lyman-FUSE mission. We find that this method should yield the 3He/4He ratio with a 1 σ uncertainty ˜50% at a spectral resolving power R=30 000 and a signal-to-noise ratio S/N=50. This method thus appears more adapted to a forehand estimation of the interstellar 3He/4He ratio than the standard profile fitting method, which should yield a 1 σ uncertainty of 10% at R=30 000 and S/N ≃ 290 (Hurwitz & Bowyer, t985). Finally, our method should be able to settle the evolutionary status of 3He if 3He has been significantly enhanced or depleted in the last 4.6 Gyr. Combined with the measurement of the deuterium abundance on the same line of sight (already programmed on HST), this might yield very important constraint on Big-Bang nucleosynthesis consistency.

  16. A record of the extraterrestrial 3He flux through the Late Cretaceous

    NASA Astrophysics Data System (ADS)

    Farley, K. A.; Montanari, A.; Coccioni, R.

    2012-05-01

    Late Cretaceous (100-73 Ma) pelagic limestones were measured for helium concentration and isotopic composition to characterize the interplanetary dust flux using 3He as a tracer. In the Bottaccione section near Gubbio, Italy, three intervals of elevated 3He concentration were detected: K1 in the Campanian stage at ˜79 Ma, K2 in the Santonian stage at ˜85 Ma, and K3 in the Turonian stage at ˜91 Ma. All three of these episodes are associated with high 3He/4He and 3He/non-carbonate ratios, consistent with their derivation from an enhanced extraterrestrial 3He flux rather than decreased carbonate sedimentation or dissolution. While K2 is modest in magnitude and duration and thus is of limited significance, K1 and K3 are each identified by a few myr interval with an ˜4-fold enhancement in mean 3He flux compared with pre-event levels. Samples from ODP Hole 762C in the Indian Ocean spanning both K2 and K3 (93-83 Ma) confirm the presence of a peak in the Turonian stage, suggesting that K3 is a global event. The K1 and K3 3He events are similar in most respects to the two peaks previously detected in the Cenozoic, suggesting a similar origin. These have been attributed to a major asteroid collision in the Late Miocene and to a shower of either comets or asteroids in the Late Eocene. Based on the age and temporal evolution of K1, we suggest that it most likely records the collision which produced the Baptistina asteroid family independently dated at ˜80 Ma. The K3 event is less easily explained. It is characterized by an unusually spiky and erratic temporal progression, suggesting an unusual abundance of very 3He rich particles not previously seen in the sedimentary 3He record. We suggest this episode arises either from a comet shower or from an asteroid shower possibly associated with dust-producing lunar impacts.

  17. Interspecies Ion Diffusion Studies using DT, DT(3He), and DT(H) Implosions

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Herrmann, H. W.; Schmitt, M. J.; Kagan, G.; McEvoy, A. M.; Hoffman, N. M.; Gales, S.; Leatherland, A.; Gatu Johnson, M.; Frenje, J.; Glevov, V. Yu; Forrest, C.

    2015-11-01

    Anomalous ICF yield degradation has been observed from gas fills containing mixtures (i.e., D(3He), DT(3He), D(Ar), and even DT). Interspecies ion diffusion theory has been suggested as a possible cause resulting from gradient-driven diffusion (i.e., pressure, electric potential, and temperature) which forces lower mass ions away from core and higher mass ions toward core. The theory predicts hydrogen addition to deuterium or tritium should result in increased yield compared to expected yield, which is opposite to 3He addition. At Omega laser facility, we have tested hydro-equivalent fills of DT, DT(3He), and DT(H) with the assumption that same fuel mass and particle pressure will provide identical convergence. Preliminary results verify a factor of 2 yield reduction relative to scaling when 3He added to DT. At DT(H) case, however, no significant yield degradation or a slight yield enhancement was observed which agrees with the interspecies ion diffusion theory. Detailed experiment results and simulation are needed to confirm the initial observation.

  18. 3He-rich SEP events observed by STEREO-A

    NASA Astrophysics Data System (ADS)

    Bućík, R.; Mall, U.; Korth, A.; Mason, G. M.; Gómez-Herrero, R.

    2013-06-01

    Using the SIT (Suprathermal Ion Telescope) instrument on STEREO-A we have examined the abundance of the rare isotope 3He during the rising activity phase of solar cycle 24 between January 2010 and December 2011. We have identified six solar energetic particle (SEP) events with enormous abundance enhancements of 3He(3He/4He>1). The events were short lasting, typically ~ 0.5 - 1 day and most of them occurred in association with high-speed solar wind streams and corotating interaction regions. With one exception the events were not associated with ~ 100 keV solar electron intensity increases. The events showed also enhanced NeS/O and Fe/O ratios. The solar images indicate that the events were generally associated with the active regions located near a coronal hole.

  19. Use of .sup.3 He.sup.30 + ICRF minority heating to simulate alpha particle heating

    DOEpatents

    Post, Jr., Douglass E.; Hwang, David Q.; Hovey, Jane

    1986-04-22

    Neutron activation due to high levels of neutron production in a first heated deuterium-tritium plasma is substantially reduced by using Ion Cyclotron Resonance Frequency (ICRF) heating of energetic .sup.3 He.sup.++ ions in a second deuterium-.sup.3 He.sup.++ plasma which exhibit an energy distribution and density similar to that of alpha particles in fusion reactor experiments to simulate fusion alpha particle heating in the first plasma. The majority of the fast .sup.3 He.sup.++ ions and their slowing down spectrum can be studied using either a modulated hydrogen beam source for producing excited states of He.sup.+ in combination with spectrometers or double charge exchange with a high energy neutral lithium beam and charged particle detectors at the plasma edge. The maintenance problems thus associated with neutron activation are substantially reduced permitting energetic alpha particle behavior to be studied in near term large fusion experiments.

  20. Heavy-baryon chiral perturbation theory approach to thermal neutron capture on {sup 3}He

    SciTech Connect

    Lazauskas, Rimantas; Park, Tae-Sun

    2011-03-15

    The cross section for radiative thermal neutron capture on {sup 3}He ({sup 3}He+n{yields}{sup 4}He+{gamma}; known as the hen reaction) is calculated based on heavy-baryon chiral perturbation theory. The relevant M1 operators are derived up to next-to-next-to-next-to-leading order (N{sup 3}LO). The initial and final nuclear wave functions are obtained from the rigorous Faddeev-Yakubovski equations for five sets of realistic nuclear interactions. Up to N{sup 3}LO, the M1 operators contain two low-energy constants, which appear as the coefficients of nonderivative two-nucleon contact terms. After determining these two constants using the experimental values of the magnetic moments of the triton and {sup 3}He, we carry out a parameter-free calculation of the hen cross section. The results are in good agreement with the data.

  1. Tritium production, management and its impact on safety for a D- sup 3 He fusion reactor

    SciTech Connect

    Sze, D.K. ); Herring, S. ); Sawan, M. )

    1991-11-01

    About three percent of the fusion energy produced by a D-{sup 3}He reactor is in the form of neutrons. Those neutrons are generated by D-D and D-T reactions, with the tritium produced by the D-D fusion. The neutrons will react with structural steel, deuterium, {sup 3}He and shielding material to produce tritium. About half of the tritium generated by the D-D reaction will not burn in the plasma and will exit as a part of the plasma exhaust. Thus, there is enough tritium produced in a D-{sup 3}He reactor and careful management will be required. The tritium produced in the shield and plasma can be managed with an acceptable effect on cost and safety. 3 refs., 2 figs., 3 tabs.

  2. Phase Diagram for 3He Films on Boron Nitride: NMR Studies

    NASA Astrophysics Data System (ADS)

    Tang, Yibing; Sullivan, Neil

    2014-03-01

    Recent studies of the thermodynamic properties of 3He films on graphite have revealed the existence of a previously undetected self-bound liquid phase at low density coverages. We report the results of NMR relaxation time studies for 3He adsorbed on hexagonal boron nitride designed to explore the dynamics of the adsorbed 3He atoms in order to identify the phase boundaries as a function of temperature. A steep thermally activated temperature dependence is observed at high temperatures (T > 2 . 6) K, followed by a linear dependence for 0 . 77 < T < 2 . 6 K. The linear dependence is consistent with that expected for thermal diffusion in the self-bound liquid state. The research was supported in part by a grant from the National Science Foundation, DMR-1303599.

  3. The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers

    NASA Astrophysics Data System (ADS)

    Çetin, Füsun

    2007-04-01

    Nuclear-pumped lasers (NPLs) are driven by the products of nuclear reactions and directly convert the nuclear energy to directed optical energy. Pumping gas lasers by nuclear reaction products has the advantage of depositing large energies per reaction. The need for high laser power output implies high operating pressure. In the case of volumetric excitation by 3He(n, p)3H reactions, however, operation at high pressure (more than a few atm) causes excessive neutron attenuation in the 3He gas. This fact adversely effects on energy deposition and, hence, laser output power and beam quality. Here, spatial and temporal variations of neutron flux inside a closed 3He -filled cylindrical laser tube have been numerically calculated for various tube radii and operating pressures by using a previously reported dynamic model for energy deposition. Calculations are made by using ITU TRIGA Mark II Reactor as the neutron source. The effects of neutron attenuation on power deposition are examined.

  4. Green's function theory for the Cheng-Schick model of 3He-4He mixtures

    NASA Astrophysics Data System (ADS)

    Siemann, R. P.; Boukahil, A.; Huber, D. L.

    2014-08-01

    In this paper, we outline a theory for the thermodynamic properties of 3He-4He mixtures in the neighborhood of the critical line and the tricritical point (TCP). The theory utilizes the Cheng-Schick (CS) lattice gas model where both the 3He and 4He atoms are treated as quantum particles on a lattice. The analysis is based on Green's function approach. Results are presented for the ordering susceptibility and the thermal averages of the occupation numbers of 3He and 4He atoms. We derive a self-consistent equation for the ordering susceptibility and use it to calculate the critical line and locate the TCP. Our findings are compared with the predictions obtained from high temperature series expansions, mean field theory and the random phase approximation (RPA).

  5. The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers

    SciTech Connect

    Cetin, Fuesun

    2007-04-23

    Nuclear-pumped lasers (NPLs) are driven by the products of nuclear reactions and directly convert the nuclear energy to directed optical energy. Pumping gas lasers by nuclear reaction products has the advantage of depositing large energies per reaction. The need for high laser power output implies high operating pressure. In the case of volumetric excitation by 3He(n, p)3H reactions, however, operation at high pressure (more than a few atm) causes excessive neutron attenuation in the 3He gas. This fact adversely effects on energy deposition and, hence, laser output power and beam quality. Here, spatial and temporal variations of neutron flux inside a closed 3He -filled cylindrical laser tube have been numerically calculated for various tube radii and operating pressures by using a previously reported dynamic model for energy deposition. Calculations are made by using ITU TRIGA Mark II Reactor as the neutron source. The effects of neutron attenuation on power deposition are examined.

  6. Excitation function of (3)He-particle induced nuclear reactions on natural palladium.

    PubMed

    Al-Abyad, M; Tárkányi, F; Ditrói, F; Takács, S

    2014-12-01

    Excitation functions of (3)He-particle induced nuclear reactions on natural palladium were measured using the standard stacked foil technique and high resolution γ-ray spectroscopy. From their threshold energies up to 27MeV, cross-sections for (nat)Pd((3)He,x)(103,104,105,106m,110m,111,112)Ag and (nat)Pd((3)He,x)(104,105,107,111m)Cd reactions were measured. The nuclear model codes TALYS-1.4, and EMPIRE-3.1 were used to describe the formation of these products. The present data were compared to theoretical results and to the available experimental data. Integral yields for some important radioisotopes were determined. PMID:25218461

  7. Realistic Calculation of the {sup 3}He + p (hep ) Astrophysical Factor

    SciTech Connect

    Marcucci, L. E.; Schiavilla, R.; Viviani, M.; Kievsky, A.; Rosati, S.

    2000-06-26

    The astrophysical factor for the proton weak capture on {sup 3}He is calculated with correlated hyperspherical harmonic wave functions corresponding to a realistic Hamiltonian consisting of the Argonne v{sub 18} two-nucleon and Urbana-IX three-nucleon interactions. The nuclear weak current has vector and axial-vector components with one- and many-body terms. All possible transitions connecting any of the p {sup 3} He S - and P -wave channels to {sup 4}He are considered. The S factor at a p {sup 3} He center-of-mass energy of 10 keV is predicted to be 10.1x10{sup -20} keV b , a factor of {approx_equal}4.5 larger than the value adopted in the standard solar model. The P -wave transitions are found to contribute about 40% of the calculated S factor. (c) 2000 The American Physical Society.

  8. Observation of the 3He(n, tp) Reaction by Detection of Far-Ultraviolet Radiation

    PubMed Central

    Thompson, Alan K.; Coplan, Michael A.; Cooper, John W.; Hughes, Patrick P.; Vest, Robert E.; Clark, Charles

    2008-01-01

    We have detected Lyman alpha radiation, 121.6 nm light produced from the n = 2 to n = 1 transition in atomic hydrogen, as a product of the 3He(n, tp) nuclear reaction occurring in a cell of 3He gas. The predominant source of this radiation appears to be decay of the 2p state of tritium produced by charge transfer and excitation collisions with the background 3He gas. Under the experimental conditions reported here we find yields of tens of Lyman alpha photons for every neutron reaction. These results suggest a method of cold neutron detection that is complementary to existing technologies that use proportional counters. In particular, this approach may provide single neutron sensitivity with wide dynamic range capability, and a class of neutron detectors that are compact and operate at relatively low voltages. PMID:27096112

  9. Longitudinal assessment of treatment effects on pulmonary ventilation using 1H/3He MRI multivariate templates

    NASA Astrophysics Data System (ADS)

    Tustison, Nicholas J.; Contrella, Benjamin; Altes, Talissa A.; Avants, Brian B.; de Lange, Eduard E.; Mugler, John P.

    2013-03-01

    The utitlity of pulmonary functional imaging techniques, such as hyperpolarized 3He MRI, has encouraged their inclusion in research studies for longitudinal assessment of disease progression and the study of treatment effects. We present methodology for performing voxelwise statistical analysis of ventilation maps derived from hyper­ polarized 3He MRI which incorporates multivariate template construction using simultaneous acquisition of IH and 3He images. Additional processing steps include intensity normalization, bias correction, 4-D longitudinal segmentation, and generation of expected ventilation maps prior to voxelwise regression analysis. Analysis is demonstrated on a cohort of eight individuals with diagnosed cystic fibrosis (CF) undergoing treatment imaged five times every two weeks with a prescribed treatment schedule.

  10. A SQUID-based 3He Co-magnetometer Readout for the SNS nEDM Experiment

    NASA Astrophysics Data System (ADS)

    Kim, Young Jin; Clayton, Steven

    2014-03-01

    A discovery of a permanent electric dipole moment (EDM) of the neutron would provide one of the most important low energy tests of the discrete symmetries beyond the Standard Model of particle physics. A new experimental neutron EDM search, to be conducted at the Spallation Neutron Source (SNS) at ORNL, has been proposed to improve the present experimental limit of 10-26 e .cm by two orders of magnitude. The experiment is based on the magnetic-resonance technique in which polarized neutrons precess at the Larmor frequency when placed in a static magnetic field; a non-zero EDM would be evident as a difference in precession frequency when a strong electric field is applied parallel vs. anti-parallel to the magnetic field. In addition to its role as neutron spin-analyzer via the spin-dependent n+3He nuclear capture process, polarized helium-3 (which has negligible EDM) will serve as co-magnetometer to correct for drifts in the magnetic field. The helium-3 magnetization signal will be read out by superconducting gradiometers coupled to SQUIDs. We describe a proposed SQUID system suitable for the complex neutron EDM apparatus, and demonstrate that the field noise in the SQUID system, tested in an environment similar to the EDM apparatus, meets the nEDM requirement.

  11. Characterizing a sewage plume using the 3H-3He dating technique

    USGS Publications Warehouse

    Shapiro, Stephanie Dunkle; LeBlanc, Denis; Schlosser, Peter; Ludin, Andrea

    1999-01-01

    An extensive 3H-3He study was performed to determine detailed characteristics of a regional flow system and a sewage plume over a distance of 4 km in a sand and gravel aquifer at Otis Air Base in Falmouth, Massachusetts. 3H-3He ages increase with depth in individual piezometer clusters and with distance along flowpaths. However, the age gradient with depth (Δt/Δz) is smaller in the plume than that in the regional waters, due to the intense recharge in the infiltration beds. The 1960s bomb peak of tritium in precipitation is archived longitudinally along a flowline through the main axis of the plume and vertically in individual piezometer clusters. On the eastern side of the sampling area, where water from Ashumet Pond forces plume water deeper into the flow system, 3H-3He ages are young at depth because the 3H-3He "clock" is reset due to outgassing of helium in the pond. A reconstruction of the tritium input functions for the regional and plume samples shows that there is no offset in the peak [3H]+[3Hetrit] concentrations for the plume and regional water, indicating that the water from supply wells for use on the base is young. The 3H-3He ages and detergent concentrations in individual wells are consistent with the beginning of use of detergents and the time period when their concentrations in sewage would have been greatest. Ages and hydraulic properties calculated using the 3H-3He data compare well with those from previous investigations and from particle-tracking simulations.

  12. Boron-coated straws as a replacement for 3He-based neutron detectors

    NASA Astrophysics Data System (ADS)

    Lacy, Jeffrey L.; Athanasiades, Athanasios; Sun, Liang; Martin, Christopher S.; Lyons, Tom D.; Foss, Michael A.; Haygood, Hal B.

    2011-10-01

    US and international government efforts to equip major seaports with large area neutron detectors, aimed to intercept the smuggling of nuclear materials, have precipitated a critical shortage of 3He gas. It is estimated that the annual demand of 3He for US security applications alone is more than the worldwide supply. This is strongly limiting the prospects of neutron science, safeguards, and other applications that rely heavily on 3He-based detectors. Clearly, alternate neutron detection technologies that can support large sensitive areas, and have low gamma sensitivity and low cost must be developed. We propose a low-cost technology based on long copper tubes (straws), coated on the inside with a thin layer of 10B-enriched boron carbide ( 10B 4C). In addition to the high abundance of boron on Earth and low cost of 10B enrichment, the boron-coated straw (BCS) detector offers distinct advantages over conventional 3He-based detectors, and alternate technologies such as 10BF 3 tubes and 10B-coated rigid tubes. These include better distribution inside moderator assemblies, many-times faster electronic signals, no pressurization, improved gamma-ray rejection, no toxic or flammable gases, and ease of serviceability. We present the performance of BCS detectors dispersed in a solid plastic moderator to address the need for portal monitoring. The design adopts the outer dimensions of currently deployed 3He-based monitors, but takes advantage of the small BCS diameter to achieve a more uniform distribution of neutron converter throughout the moderating material. We show that approximately 63 BCS detectors, each 205 cm long, distributed inside the moderator, can match or exceed the detection efficiency of typical monitors fitted with a 5 cm diameter 3He tube, 187 cm long, pressurized to 3 atm.

  13. JPL research to develop a He-3/He-4 dilution refrigerator for space applications

    NASA Technical Reports Server (NTRS)

    Petrac, D.; Israelsson, U. E.; Jackson, H. W.; Strayer, D. M.

    1990-01-01

    A research program to develop a He-3/He-4 solution refrigerator for space applications is underway. The results of the effort to use an electric field as a substitute for gravity to control the He-3/He-4 mixture interface that separates phases in terrestrial units are described. Further, experimental results obtained from an engineering model of a single-cycle dilution refrigerator with a mixing chamber capable of operating in a zero-gravity environment are described. Future research and development plans are outlined, in particular the need to test the operation of a single-cycle as well as a continuously operating dilution refrigerator in space.

  14. B phase with polar distortion in superfluid {sup 3}He in “ordered” aerogel

    SciTech Connect

    Dmitriev, V. V. Senin, A. A.; Soldatov, A. A.; Surovtsev, E. V.; Yudin, A. N.

    2014-12-15

    The properties of the low-temperature superfluid phase of {sup 3}He in “nematically ordered” aerogel in which strands are almost parallel to one another are investigated by nuclear magnetic resonance methods. Such a strong anisotropy of the aerogel affects the phase diagram of {sup 3}He and the structure of superfluid phases. A theoretical model of the B phase with polar distortion is developed. It is shown that this model successfully describes the observed properties of the low-temperature phase.

  15. Resonance transition 795-nm Rubidium laser using 3He buffer gas

    SciTech Connect

    Wu, S S; Soules, T F; Page, R H; Mitchell, S C; Kanz, V K; Beach, R J

    2007-08-02

    We report the first demonstration of a 795-nm Rubidium resonance transition laser using a buffer gas consisting of pure {sup 3}He. This follows our recent demonstration of a hydrocarbon-free 795-nm Rubidium resonance laser which used naturally-occurring He as the buffer gas. Using He gas that is isotopically enriched with {sup 3}He yields enhanced mixing of the Rb fine-structure levels. This enables efficient lasing at reduced He buffer gas pressure, improving thermal management in high average power Rb lasers and enhancing the power scaling potential of such systems.

  16. High-sensitivity measurement of 3He-4He isotopic ratios for ultracold neutron experiments

    NASA Astrophysics Data System (ADS)

    Mumm, H. P.; Huber, M. G.; Bauder, W.; Abrams, N.; Deibel, C. M.; Huffer, C. R.; Huffman, P. R.; Schelhammer, K. W.; Janssens, R.; Jiang, C. L.; Scott, R. H.; Pardo, R. C.; Rehm, K. E.; Vondrasek, R.; Swank, C. M.; O'Shaughnessy, C. M.; Paul, M.; Yang, L.

    2016-06-01

    Research efforts ranging from studies of solid helium to searches for a neutron electric dipole moment require isotopically purified helium with a ratio of 3He to 4He at levels below that which can be measured using traditional mass spectroscopy techniques. We demonstrate an approach to such a measurement using accelerator mass spectroscopy, reaching the 10-14 level of sensitivity, several orders of magnitude more sensitive than other techniques. Measurements of 3He/4He in samples relevant to the measurement of the neutron lifetime indicate the need for substantial corrections. We also argue that there is a clear path forward to sensitivity increases of at least another order of magnitude.

  17. A validation of the 3H/3He method for determining groundwater recharge

    NASA Astrophysics Data System (ADS)

    Solomon, D. K.; Schiff, S. L.; Poreda, R. J.; Clarke, W. B.

    1993-09-01

    Tritium and He isotopes have been measured at a site where groundwater flow is nearly vertical for a travel time of 100 years and where recharge rates are spatially variable. Because the mid-1960s 3H peak (arising from aboveground testing of thermonuclear devices) is well-defined, the vertical groundwater velocity is known with unusual accuracy at this site. Utilizing 3H and its stable daughter 3He to determine groundwater ages, we compute a recharge rate of 0.16 m/yr, which agrees to within about 5% of the value based on the depth of the 3H peak (measured both in 1986 and 1991) and two-dimensional modeling in an area of high recharge. Zero 3H/3He age occurs at a depth that is approximately equal to the average depth of the annual low water table, even though the capillary fringe extends to land surface during most of the year at the study site. In an area of low recharge (0.05 m/yr) where the 3H peak (and hence the vertical velocity) is also well-defined, the 3H/3He results could not be used to compute recharge because samples were not collected sufficiently far above the 3H peak; however, modeling indicates that the 3H/3He age gradient near the water table is an accurate measure of vertical velocities in the low-recharge area. Because 3H and 3He have different diffusion coefficients, and because the amount of mechanical mixing is different in the area of high recharge than in the low-recharge area, we have separated the dispersive effects of mechanical mixing from molecular diffusion. We estimate a longitudinal dispersivity of 0.07 m and effective diffusion coefficients for 3H (3HHO) and 3He of 2.4×10-5 and 1.3×10-4 m2/day, respectively. Although the 3H/3He age gradient is an excellent indicator of vertical groundwater velocities above the mid-1960s 3H peak, dispersive mixing and diffusive loss of 3He perturb the age gradient near and below the 3H peak.

  18. Polarisation and compression of {sup 3}He for Magnetic Resonance Imaging purposes

    SciTech Connect

    Geurts, D. G.; Brand, J. F. J. van den; Bulten, H. J.; Poolman, H. R.; Ferro-Luzzi, M.; Nicolay, K.

    1998-01-20

    Magnetic Resonance Imaging is often used in medical science as a diagnostic tool for the human body. Conventional MRI uses the NMR signal from the protons of water molecules in tissue to image the interior of the patient's body. However, for certain areas such as the lungs and airways, the usage of a highly polarised gas yields better results. We are currently constructing an apparatus that uses polarised {sup 3}He gas to produce detailed images of those signal-deficient moyeties. We also plan to study possible uptake of polarised {sup 3}He gas by the circulatory system to image other organs.

  19. Two-body pion absorption on {sup 3}He at threshold

    SciTech Connect

    Lee, T.S.H.; Kiang, L.L.; Riska, D.O.

    1995-08-01

    We showed that a drastic reduction of the ratio of the rates of the reactions {sup 3}He({pi}{sup -},nn) and {sup 3}He({pi}{sup -},np) for stopped pions is obtained once the effect of the short-range two-nucleon components of the axial charge operator for nuclear systems is taken into account. In a calculation using realistic models of nucleon-nucleon interactions in the construction of these short-range components of the axial charge operator, the predicted ratios can be brought to within 10-20% of the empirical value. A paper describing our results was published.

  20. Electronic structure of magnetic semiconductor CdCr{sub 2}Te{sub 4}: A possible spin-dependent symmetry filter

    SciTech Connect

    Sims, H.; Butler, W. H.; Ramasamy, K.; Gupta, A.

    2013-11-04

    We present a theoretical investigation of the electronic and magnetic structure of spinel CdCr{sub 2}Te{sub 4} using density functional theory, its extensions via onsite Hubbard U interactions, and a screened-hybrid-functional exchange potential. We find that the ground state is semiconducting within the latter approach, and within this magnetic-semiconducting system, we compute the complex band structure, finding a slowly decaying evanescent Δ{sup ~}{sub 1} state possibly suitable for realizing a spin-dependent symmetry filter effect.

  1. Degassing of 3H/ 3He, CFCs and SF 6 by denitrification: Measurements and two-phase transport simulations

    NASA Astrophysics Data System (ADS)

    Visser, Ate; Schaap, Joris D.; Broers, Hans Peter; Bierkens, Marc F. P.

    2009-01-01

    The production of N 2 gas by denitrification may lead to the appearance of a gas phase below the water table prohibiting the conservative transport of tracer gases required for groundwater dating. We used a two-phase flow and transport model (STOMP) to study the reliability of 3H/ 3He, CFCs and SF 6 as groundwater age tracers under agricultural land where denitrification causes degassing. We were able to reproduce the amount of degassing ( R2 = 69%), as well as the 3H ( R2 = 79%) and 3He* ( R2 = 76%) concentrations observed in a 3H/ 3He data set using simple 2D models. We found that the TDG correction of the 3H/ 3He age overestimated the control 3He/ 3He age by 2.1 years, due to the accumulation of 3He* in the gas phase. The total uncertainty of degassed 3H/ 3He ages of 6 years (± 2 σ) is due to the correction of degassed 3He* using the TDG method, but also due to the travel time in the unsaturated zone and the diffusion of bomb peak 3He*. CFCs appear to be subject to significant degradation in anoxic groundwater and SF 6 is highly susceptible to degassing. We conclude that 3H/ 3He is the most reliable method to date degassed groundwater and that two-phase flow models such as STOMP are useful tools to assist in the interpretation of degassed groundwater age tracer data.

  2. The Gas Motion Due To Non-Uniform Heating By 3He(n,p)3H Reactions In The Nuclear-Pumped3He -Lasers

    NASA Astrophysics Data System (ADS)

    Çetin, Füsun

    2007-04-01

    In the nuclear pumped-lasers, the passage of these energetic charged particles through gas results in a non-uniform volumetric energy deposition. This spatial non-uniformity induces a gas motion, which results in density and hence refractive index gradients that affects the laser's optical behaviour. The motion of 3He gas in a closed cavity is studied when it experiences transient and spatially non-uniform volumetric heating caused by the passage of 3He(n,p)3H reaction products. Gas motion is described by the radial velocity field of gas flow. Spatial and temporal variations of radial gas velocity are calculated for various tube parameters by using a dynamic energy deposition model. In the calculations, it is assumed that the laser tube is irradiated with neutrons from the pulse at a peak power of 1200 MW corresponding to a maximum thermal neutron flux of 8×1016 n / cm2sn in the central channel of ITU TRIGA Mark II Reactor. Results are examined.

  3. The Gas Motion Due To Non-Uniform Heating By 3He(n,p)3H Reactions In The Nuclear-Pumped3He -Lasers

    SciTech Connect

    Cetin, Fuesun

    2007-04-23

    In the nuclear pumped-lasers, the passage of these energetic charged particles through gas results in a non-uniform volumetric energy deposition. This spatial non-uniformity induces a gas motion, which results in density and hence refractive index gradients that affects the laser's optical behaviour. The motion of 3He gas in a closed cavity is studied when it experiences transient and spatially non-uniform volumetric heating caused by the passage of 3He(n,p)3H reaction products. Gas motion is described by the radial velocity field of gas flow. Spatial and temporal variations of radial gas velocity are calculated for various tube parameters by using a dynamic energy deposition model. In the calculations, it is assumed that the laser tube is irradiated with neutrons from the pulse at a peak power of 1200 MW corresponding to a maximum thermal neutron flux of 8x1016 n / cm2sn in the central channel of ITU TRIGA Mark II Reactor. Results are examined.

  4. Neutron dosimetry at commercial nuclear plants. Final report of Subtask C: /sup 3/He neutron spectrometer

    SciTech Connect

    Brackenbush, L.W.; Reece, W.D.; Tanner, J.E.

    1984-09-01

    In commercial nuclear power plants, personnel routinely enter containment for maintenance and inspections while the reactor is operating and can be exposed to intense neutron fields. The low-energy neutron fields found in reactor containment cause problems in proper interpretation of TLD-albedo dosimeters and survey instrument readings. This report describes a technique that can aid plant health physicists to improve the accuracy of personnel neutron dosimetry programs. A /sup 3/He neutron spectrometer can be used to measure neutron energy spectra and determine dose equivalent rates at work locations inside containment. Energy correction factors for TLD-albedo dosimeters can be determined from the measured spectra if the dosimeter energy response is known, or from direct measurements with dosimeters placed on phantoms at locations where the dose equivalent rate has been measured. This report describes how to assemble a spectrometer system using only commercially available components, how to use it for reactor energy spectrum measurements, and how to analyze the data and interpret the results. Both /sup 3/He and multisphere spectrometers were used to measure neutron energy spectra and dose equivalent at three PWRs and one BWR. In general, the /sup 3/He spectrometer measures higher dose equivalent rates than the multisphere spectrometer. In the energy range from 10 keV to 1 MeV, the dose equivalents measured by the /sup 3/He spectrometer and multisphere spectrometer agree within about 35% for the spectra measured.

  5. Electron screening in the {sup 3}He(d,p){sup 4}He reaction

    SciTech Connect

    Barker, F. C.

    2007-02-15

    A reanalysis of data for the {sup 3}He(d,p){sup 4}He reaction obtained using the Trojan-horse method, together with data from a direct measurement, leads to an electron-screening potential that is not consistent with the adiabatic limit, but it is consistent with a previous value from different data.

  6. 3D MRI of non-Gaussian 3He gas diffusion in the rat lung

    NASA Astrophysics Data System (ADS)

    Jacob, Richard E.; Laicher, Gernot; Minard, Kevin R.

    2007-10-01

    In 3He magnetic resonance images of pulmonary air spaces, the confining architecture of the parenchymal tissue results in a non-Gaussian distribution of signal phase that non-exponentially attenuates image intensity as diffusion weighting is increased. Here, two approaches previously used for the analysis of non-Gaussian effects in the lung are compared and related using diffusion-weighted 3He MR images of mechanically ventilated rats. One approach is model-based and was presented by Yablonskiy et al., while the other approach utilizes the second order decay contribution that is predicted from the cumulant expansion theorem. Total lung coverage is achieved using a hybrid 3D pulse sequence that combines conventional phase encoding with sparse radial sampling for efficient gas usage. This enables the acquisition of nine 3D images using a total of only ˜1 L of hyperpolarized 3He gas. Diffusion weighting ranges from 0 s/cm 2 to 40 s/cm 2. Results show that the non-Gaussian effects of 3He gas diffusion in healthy rat lungs are directly attributed to the anisotropic geometry of lung microstructure as predicted by the Yablonskiy model, and that quantitative analysis over the entire lung can be reliably repeated in time-course studies of the same animal.

  7. Direct Observation of a Majorana Quasiparticle Heat Capacity in 3He

    NASA Astrophysics Data System (ADS)

    Bunkov, Y. M.

    2014-04-01

    The Majorana fermion, which acts as its own antiparticle, was suggested by Majorana in 1937 (Nuovo Cimento 14:171). While no stable particle with Majorana properties has yet been observed, Majorana quasiparticles (QP) may exist at the boundaries of topological insulators. Here we report the preliminary results of direct observation of Majorana QPs by a precise measurements of superfluid 3He heat capacity. The bulk superfluid 3He heat capacity falls exponentially with cooling at the temperatures significantly below the energy gap. Owing to the zero energy gap mode the Majorana heat capacity falls in a power law. The Majorana heat capacity can be larger than bulk one at some temperature, which depends on surface to volume ratio of the experimental cell. Some times ago we developed the Dark matter particles detector (DMD) on a basis of superfluid 3He which is working at the frontier of extremely low temperatures (Winkelmann et al., Nucl. Instrum. Meth. A 559:384-386, 2006). Here we report the observation of zero gap mode of Majorana, follows from the new analyses of DMD heat capacity, published early. We have found a 10 % deviation from the bulk superfluid 3He heat capacity at the temperature of 135 μK. This deviation corresponds well to the theoretical value for Majorana heat capacity at such low temperature. (Note, there were no fitting parameters).

  8. Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis.

    PubMed

    Eggleton, Peter P; Dearborn, David S P; Lattanzio, John C

    2006-12-01

    Low-mass stars, approximately 1 to 2 solar masses, near the Main Sequence are efficient at producing the helium isotope 3He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3He with the predictions of both stellar and Big Bang nucleosynthesis. Here we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus, we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He. PMID:17068226

  9. Precision measurement of the neutron magnetic form factor from {sup 3}He(e, e')

    SciTech Connect

    Dipangkar Dutta

    2000-12-12

    A precision measurement of the inclusive quasielastic transverse asymmetry A{sub T'} from {sup 3}He(e, e') was completed recently at Hall A at Jefferson Lab (E95-001). The preliminary results on the neutron magnetic form factor at low Q{sup 2} are presented here.

  10. Association of 3He-rich solar energetic particles with large-scale coronal waves

    NASA Astrophysics Data System (ADS)

    Bucik, Radoslav; Innes, Davina; Guo, Lijia; Mason, Glenn M.; Wiedenbeck, Mark

    2016-07-01

    Impulsive or 3He-rich solar energetic particle (SEP) events have been typically associated with jets or small EUV brightenings. We identify 30 impulsive SEP events from ACE at L1 during the solar minimum period 2007-2010 and examine their solar sources with high resolution STEREO-A EUV images. At beginning of 2007, STEREO-A was near the Earth while at the end of the investigated period, when there were more events, STEREO-A was leading the Earth by 90°. Thus STEREO-A provided a better (more direct) view on 3He-rich flares generally located on the western Sun's hemisphere. Surprisingly, we find that about half of the events are associated with large-scale EUV coronal waves. This finding provides new insights on acceleration and transport of 3He-rich SEPs in solar corona. It is believed that elemental and isotopic fractionation in impulsive SEP events is caused by more localized processes operating in the flare sites. The EUV waves have been reported in gradual SEP events in association with fast coronal mass ejections. To examine their role on 3He-rich SEPs production the energy spectra and relative abundances are discussed. R. Bucik is supported by the Deutsche Forschungsgemeinschaft under grant BU 3115/2-1.

  11. Single-collision approximation for p{sup 3}-He elastic scattering at low energy

    SciTech Connect

    Abusini, M.

    2009-06-15

    A theoretical approach to studying four-body reactions of p{sup 3}-He elastic scattering that takes consistently into account the single-collision mechanism is reported. The theoretical results obtained by this method were compared with experimental data, and the agreement is found to be quite satisfactory.

  12. Phase-space analysis of convection in a /sup 3/He - superfluid /sup 4/He solution

    SciTech Connect

    Haucke, H.; Maeno, Y.

    1982-01-01

    Observations have been made on thermal convection below 1K in a dilute solution of /sup 3/He in superfluid /sup 4/He contained in a cylindrical cell of aspect ratio GAMMA = 1.20. Complicated oscillatory phenomena were observed with a high degree of reproducibility using two temperature sensors. Phase-space analysis suggests a description in terms of strange-attractor dynamics.

  13. Pressure broadening and shift of K D1 and D2 lines in the presence of 3He and 21Ne

    NASA Astrophysics Data System (ADS)

    Li, Rujie; Li, Yang; Jiang, Liwei; Quan, Wei; Ding, Ming; Fang, Jiancheng

    2016-06-01

    Due to the collisions with alkali-metal atoms, the buffer gases used in spin-exchange optical pumping systems induce a broadening of spectral profiles and a shift in the resonance frequency. Here we report the pressure broadening and shift rates of K D 1 and D 2 lines in the presence of 21Ne for the first time and values for 3He have been reinvestigated by means of laser absorption spectroscopy. We have also examined the temperature dependence of these collisional effects in a range of 435-458 K. A comparison for the broadening and shift rates to those of other isotopes, 4He and 20Ne, is presented.

  14. Pressure broadening and shift of K D1 and D2 lines in the presence of 3He and 21Ne

    NASA Astrophysics Data System (ADS)

    Li, Rujie; Li, Yang; Jiang, Liwei; Quan, Wei; Ding, Ming; Fang, Jiancheng

    2016-06-01

    Due to the collisions with alkali-metal atoms, the buffer gases used in spin-exchange optical pumping systems induce a broadening of spectral profiles and a shift in the resonance frequency. Here we report the pressure broadening and shift rates of K D1 and D2 lines in the presence of 21Ne for the first time and values for 3He have been reinvestigated by means of laser absorption spectroscopy. We have also examined the temperature dependence of these collisional effects in a range of 435-458 K. A comparison for the broadening and shift rates to those of other isotopes, 4He and 20Ne, is presented.

  15. Regional Ventilation Changes in Severe Asthma after Bronchial Thermoplasty with 3He MR Imaging and CT

    PubMed Central

    Thomen, Robert P.; Sheshadri, Ajay; Quirk, James D.; Kozlowski, Jim; Ellison, Henry D.; Szczesniak, Rhonda D.; Castro, Mario

    2015-01-01

    Purpose To quantify regional lung ventilation in healthy volunteers and patients with severe asthma (both before and after thermoplasty) by using a combination of helium 3 (3He) magnetic resonance (MR) imaging and computed tomography (CT), with the intention of developing more effective image-guided treatments for obstructive lung diseases. Materials and Methods With approval of the local institutional review board, informed consent, and an Investigational New Drug Exemption, six healthy volunteers and 10 patients with severe asthma were imaged in compliance with HIPAA regulations by using both multidetector CT and 3He MR imaging. Individual bronchopulmonary segments were labeled voxel by voxel from the CT images and then registered to the 3He MR images by using custom software. The 3He signal intensity was then analyzed by evaluating the volume-weighted fraction of total-lung signal intensity present in each segment (segmental ventilation percentage [SVPsegmental ventilation percentage]) and by identifying the whole-lung defect percentage and the segmental defect percentage. Of the 10 patients with asthma, seven received treatment with bronchial thermoplasty and were imaged with 3He MR a second time. Changes in segmental defect percentages and whole-lung defect percentages are presented. Results Ventilation measures for healthy volunteers yielded smaller segment-to-segment variation (mean SVPsegmental ventilation percentage, 100% ± 18 [standard deviation]) than did the measures for patients with severe asthma (mean SVPsegmental ventilation percentage, 97% ± 23). Patients with asthma also demonstrated larger segmental defect percentages (median, 13.5%; interquartile range, 8.9%–17.8%) than healthy volunteers (median, 6%; interquartile range, 5.6%–6.3%). These quantitative results confirm what is visually observed on the 3He images. A Spearman correlation of r = −0.82 was found between the change in whole-lung defect percentage and the number of days between

  16. 3HE RECOVERY FROM A TRITIUM-AGED LANA75 SAMPLE

    SciTech Connect

    Shanahan, K.

    2010-12-01

    {sup 3}He recovery is a topic of recent interest. One potential recovery source is from metal hydride materials once used to store tritium, as the decay product, {sup 3}He, is primarily trapped in the metal lattice, usually in bubbles, with such materials. In 2001, a Tritium Exposure Program (TEP) sample known as LANA75-SP1 was retired and the material was removed from the test cell and stored. Subsequently scoping temperature programmed desorption (TPD) experiments were conducted on that material to see what it might take to drive out He and residual H isotopes (the heel). Two experiments consisted of heating the sample in the presence of an excess of tin (the so-called Sn fusion experiment), and one was a simple TPD with no additives. Prior data on the so-called '21-month bed' material in the 1980's had produced {approx}21 cc of gas per gram of a LANA30 material (LaNi4.7Al0.3), with approximately 67% of that being {sup 3}He and the rest being D{sub 2} (Fig.3). However, the material had to be heated in excess of 850 C to obtain that level. Heating to less produced approximately half that amount of gas. The data also showed that {sup 3}He was released at different temperatures than the residual hydrogen isotopes. Unfortunately this implies full {sup 3}He recovery will be a difficult process. Therefore, it seemed advisable to attempt to extract as much information from the 3 scoping experiments from 2001-2 as possible.

  17. 3H/3He age data in assessing the susceptibility of wells to contamination

    USGS Publications Warehouse

    Manning, A.H.; Solomon, D.K.; Thiros, S.A.

    2005-01-01

    Regulatory agencies are becoming increasingly interested in using young-ground water dating techniques, such as the 3H/3He method, in assessing the susceptibility of public supply wells (PSWs) to contamination. However, recent studies emphasize that ground water samples of mixed age may be the norm, particularly from long-screened PSWs, and tracer-based "apparent" ages can differ substantially from actual mean ages for mixed-age samples. We present age and contaminant data from PSWs in Salt Lake Valley, Utah, that demonstrate the utility of 3H and 3He measurements in evaluating well susceptibility, despite potential age mixing. Initial 3H concentrations (measured 3H + measured tritiogenic 3He) are compared to those expected based on the apparent 3H/3He age and the local precipitation 3H record. This comparison is used to determine the amount of modern water (recharged after ???1950) vs. prebomb water (recharged before ???1950) samples might contain. Concentrations of common contaminants were also measured using detection limits generally lower than those used for regulatory purposes. A clear correlation exists between the potential magnitude of the modern water fraction and both the occurrence and concentration of contaminants. For samples containing dominantly modern water based on their initial 3H concentrations, potential discrepancies between apparent 3H/ 3He ages and mean ages are explored using synthetic samples that are random mixtures of different modern waters. Apparent ages can exceed mean ages by up to 13 years for these samples, with an exponential age distribution resulting in the greatest discrepancies.

  18. Solar Sources of 3He-rich Solar Energetic Particle Events in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Nitta, Nariaki V.; Mason, Glenn M.; Wang, Linghua; Cohen, Christina; Wiedenbeck, Mark E.

    2015-04-01

    We still do not understand the origin of impulsive SEP events enriched in 3He and heavy ions. A major impediment may be the difficulty to observe them in the corona, apart from the common knowledge that 3He-rich SEP events are correlated with longer-than-metric type III radio bursts and <100 keV electron events. This is because their X-ray and EUV signatures tend to be tiny and short-lived. Using high-cadence and high-sensitivity EUV images obtained by SDO/AIA, we investigate the solar sources of 26 3He-rich SEP events during solar cycle 24 that were well-observed by ACE. The source locations are further confirmed in data from STEREO/EUVI, which capture solar activities in the regions inaccessible from the Earth. We confirm that 3He-rich events have a broad longitudinal distribution (including locations well behind the west limb) and that a frequent association with coronal jets and narrow CMEs. Some events were seen in association with eruptions of closed structures and large-scale coronal propagating fronts (LCPFs, aka EUV waves). While these LCPFs may account for the occasional mismatching polarities at the source region and L1 in such a way that the particles are transported to and released at a region that has the opposite polarity, their associated CMEs may not be fast enough to drive shock waves for particle acceleration. Moreover, open field lines from PFSS models may not be correct for the entire Sun although they often look reasonable in discrete locations. We also discuss the apparent lack of correlation between the solar sources and the basic properties of 3He-rich SEP events.

  19. Two-dimensional MAS NMR correlation protocols involving double-quantum filtering of quadrupolar spin-pairs.

    PubMed

    Edén, Mattias

    2010-05-01

    Three two-dimensional (2D) NMR homonuclear correlation techniques invoking double-quantum (2Q) filtration of the central transitions of half-integer spins are evaluated numerically and experimentally. They correlate directly detected single-quantum (1Q) coherences in the t(2) domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t(1)) dimension. We employ experimental (23)Na and (27)Al NMR on sodium sulfite and the natural mineral sillimanite (SiAl(2)O(5)), in conjunction with simulated 2D spectra from pairs of dipolar-recoupled spins-3/2 and 5/2 at different external magnetic fields, to compare the correlation strategies from the viewpoints of 2D spectral resolution, signal sensitivity, implementational aspects and their relative merits for establishing internuclear proximities and quadrupolar tensor orientations. PMID:20202872

  20. A validation of the [sup 3]H/[sup 3]He method for determining groundwater recharge

    SciTech Connect

    Solomon, D.K. ); Schiff, S.L. ); Poreda, R.J. ); Clarke, W.B. )

    1993-09-01

    Tritium and He isotopes have been measured at a site where groundwater flow is nearly vertical for a travel time of 100 years and where recharge rates are spatially variable. Because the mid-1960s [sup 3]H peak (arising from aboveground testing of thermonuclear devices) is well-defined, the vertical groundwater velocity is known with unusual accuracy at this site. Utilizing [sup 3]H and its stable daughter [sup 3]He to determine groundwater ages, we compute a recharge rate of 0.16 m/yr, which agrees to within about 5% of the value based on the depth of the [sup 3]H peak (measured both in 1986 and 1991) and two-dimensional modeling in an area of high recharge. Zero [sup 3]H/[sup 3]He age occurs at a depth that is approximately equal to the average depth of the annual low water table, even though the capillary fringe extends to land surface during most of the year at the study site. In an area of low recharge (0.05 m/yr) where the [sup 3]H peak (and hence the vertical velocity) is also well-defined, the [sup 3]H/[sup 3]He results could not be used to compute recharge because samples were not collected sufficiently far above the [sup 3]H peak; however, modeling indicates that the [sup 3]H/[sup 3]He age gradient near the water table is an accurate measure of vertical velocities in the low-recharge area. Because [sup 3]H and [sup 3]He have different diffusion coefficients, and because the amount of mechanical mixing is different in the area of high recharge than in the low-recharge area, we have separated the dispersive effects of mechanical mixing from molecular diffusion. We estimate a longitudinal dispersivity of 0.07 m and effective diffusion coefficients for [sup 3]H ([sup 3]HHO) and [sup 3]He of 2.4 x 10[sup [minus]5] and 1.3 x 10[sup [minus]4] m[sup 2]/day, respectively. 26 refs., 8 figs., 1 tab.