Science.gov

Sample records for 3he spin filters

  1. Optical Pumping / Spin Exchange ^3He Neutron Spin Filter Development

    NASA Astrophysics Data System (ADS)

    Hwang, Shenq-Rong; Coulter, Kevin P.; Chupp, Timothy E.; Welsh, Robert C.

    1998-04-01

    We have instrumented a thermal neutron beam line at the 2MW Ford reactor at the University of Michigan to develop a ^3He neutron spin filter test stand. Due to a large, spin depedent neutron cross section at low energies, polarized ^3He can be used as a neutron spin filter. Our ^3He spin filter is a 10 amagat-cm ^3He cell polarized via optical pumping/spin exchange with Rb. The filter is made of Corning 7056 glass filled with Rb , several atmosphere of ^3He and a few hundred torr nitrogen as buffer gas. We apply two 15W diode array lasers to optically pump Rb. In this presentation we will discuss some progress of this development, including a rotating oven design and a stepping motor driven neutron chopper. Preliminary results of the 10 amagat-cm filter will be presented and compared with theoretical calculations. A study of systematic errors from the data acquisition system and the neutron chopper will also be discussed.

  2. Polarized (3) He Spin Filters for Slow Neutron Physics.

    PubMed

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

    2005-01-01

    Polarized (3)He 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 (3)He spin filters for slow neutron physics. Besides the essential goal of maximizing the (3)He 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 (3)He, but will focus on SE. We will discuss the recent demonstration of 75 % (3)He polarization, temperature-dependent relaxation mechanism of unknown origin, cell development, spectrally narrowed lasers, and hybrid spin-exchange optical pumping.

  3. 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

  4. ^3He neutron spin filters for polarized neutron scattering.

    NASA Astrophysics Data System (ADS)

    Chen, Wangchun; Borchers, Julie; Chen, Ying; O'Donovan, Kevin; Erwin, Ross; Lynn, Jeffrey; Majkrzak, Charles; McKenney, Sarah; Gentile, Thomas

    2006-03-01

    Polarized neutron scattering (PNS) is a powerful tool that probes the magnetic structures in a wide variety of magnetic materials. Polarized ^3He gas, produced by optical pumping, can be used to polarize or analyze neutron beams because of the strong spin dependence of the neutron absorption cross section for ^3He. Polarized ^3He neutron spin filters (NSF) have been of great interest in PNS community due to recent significant improvement of their performance. Here I will discuss successful applications using ^3He NSFs in polarized neutron reflectometry (PNR) and triple-axis spectrometry (TAS). In PNR, a ^3He NSF in conjunction with a position-sensitive detector allows for efficient polarization analysis of off-specular scattering over a broad range of reciprocal space. In TAS, a ^3He NSF in combination with a double focusing pyrolytic graphite monochromator provides greater versatility and higher intensity compared to a Heusler polarizer. Finally I will present the results from patterned magnetically-coupled thin films in PNR and our first ``proof-of-principle'' experiment in TAS, both of which were performed using ^3He NSF(s) at the NIST Center for Neutron Research.

  5. 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.

  6. Recent advancements of wide-angle polarization analysis with 3He neutron spin filters

    NASA Astrophysics Data System (ADS)

    Chen, W. C.; Gentile, T. R.; Ye, Q.; Kirchhoff, A.; Watson, S. M.; Rodriguez-Rivera, J. A.; Qiu, Y.; Broholm, C.

    2016-09-01

    Wide-angle polarization analysis with polarized 3He based neutron spin filters (NSFs) has recently been employed on the Multi-Axis Crystal Spectrometer (MACS) at the National Institute of Standards and Technology Center for Neutron Research (NCNR). Over the past several years, the apparatus has undergone many upgrades to address the fundamental requirements for wide angle polarization analysis using spin exchange optical pumping based 3He NSFs. In this paper, we report substantial improvements in the on-beam-line performance of the apparatus and progress toward routine user capability. We discuss new standard samples used for 3He NSF characterization and the flipping ratio measurement on MACS. We further discuss the management of stray magnetic fields produced by operation of superconducting magnets on the MACS instrument, which can significantly reduce the 3He polarization relaxation time. Finally, we present the results of recent development of horseshoe-shaped wide angle cells.

  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. PMID:27308141

  8. A New Method for Precision Cold Neutron Polarimetry Using a (3)He Spin Filter.

    PubMed

    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 (3)He 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.

  9. 3He spin filter based polarized neutron capability at the NIST Center for Neutron Research

    NASA Astrophysics Data System (ADS)

    Chen, W. C.; Gentile, T. R.; Erwin, R.; Watson, S.; Ye, Q.; Krycka, K. L.; Maranville, B. B.

    2014-07-01

    A 3He neutron spin filter (NSF) program for polarized neutron scattering was launched in 2006 as part of the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) Expansion Initiative. The goal of the project was to enhance the NCNR polarized neutron measurement capabilities. Benefitting from more than a decade's development of spin-exchange optical pumping (SEOP) at NIST, we planned to employ SEOP based 3He neutron spin filters for the polarized neutron scattering community. These 3He NSF devices were planned for use on different classes of polarized neutron instrumentation at the NCNR, including triple-axis spectrometers (TAS), small-angle neutron scattering instruments (SANS), reflectometers, and wide-angle polarization analysis. Among them, the BT-7 thermal TAS, NG-3 SANS, and MAGIK reflectometer have already been in the user program for routine polarized beam experiments. Wide-angle polarization analysis on Multi-Axis Crystal Spectrometer (MACS) has been developed for user experiments. We describe briefly the SEOP systems dedicated for polarized beam experiments and polarizing neutron development for each instrument class. We summarize the current status and polarized neutronic performance for each instrument. We present a 3He NSF hardware and software interface to allow for synchronization of 3He polarization inversion (neutron spin flipping) and free-induction decay (FID) nuclear magnetic resonance (NMR) measurements with neutron data collection.

  10. 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.

  11. Developments of In-Situ SEOP Polarized 3He Neutron Spin Filter in Japan

    NASA Astrophysics Data System (ADS)

    Kira, H.; Sakaguchi, Y.; Oku, T.; Suzuki, J.; Nakamura, M.; Arai, M.; Endoh, Y.; Chang, L. J.; Kakurai, K.; Arimoto, Y.; Ino, T.; Shimizu, H. M.; Kamiyama, T.; Ohoyama, K.; Hiraka, H.; Tsutsumi, K.; Yamada, K.

    2011-06-01

    We launched the polarized 3He neutron spin filters (NSF) project in order to provide neutron polarization for the pulsed neutron beams in Japan. We adopted the in-situ spin exchange optical pumping (SEOP) technique to polarize the nuclear spin of 3He atoms because it has some advantages for our applications. The overall system size is compact and it avoids the problem of the time decay of nuclear spin of 3He thus suppressing the costs of maintenance and providing other advantages [1, 2] with respect to data analysis and quality. In this paper, we performed pulsed neutron beam tests of our compact in-situ SEOP NSF system at the BL10 beamline in the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex (J-PARC). The polarization of the 3He gas reached was 73 % and a pump-up time constant of 9.5 h was observed. This paper is a status report about the development of in-situ SEOP NSF system for the pulsed beam at J-PARC.

  12. Neutron Polarization Measurements with a 3He Spin Filter for the NPDGamma Experiment

    NASA Astrophysics Data System (ADS)

    Musgrave, Matthew

    2012-10-01

    The Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source (SNS) provides a pulsed beam of polarized cold neutrons for the NPDGamma experiment which intends to measure the parity violating asymmetry in the emitted gamma rays from the capture of polarized neutrons on protons in a para-hydrogen target. The neutrons are polarized by a multi-channel super mirror polarizer, and the polarization of each neutron pulse can be flipped with an RF spin rotator. The accuracy of the NPDGamma experiment and various commissioning experiments is dependent on the polarization of the neutron beam and the efficiency of the RF spin rotator. These parameters are measured with a polarized 3He spin filter at multiple points in the beam cross section and with multiple 3He polarizations. The measured neutron polarization is compared to a McStas model to validate our results and our beam averaging technique. The analysis methods, background effects, and results will be discussed.

  13. 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.

  14. 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.

  15. Development of a compact in situ polarized {sup 3}He neutron spin filter at Oak Ridge National Laboratory

    SciTech Connect

    Jiang, C. Y.; Tong, X. Brown, D. R.; Kadron, B. J.; Robertson, J. L.; Chi, S.; Christianson, A. D.; Winn, B. L.

    2014-07-15

    We constructed a compact in situ polarized {sup 3}He neutron spin filter based on spin-exchange optical pumping which is capable of continuous pumping of the {sup 3}He gas while the system is in place in the neutron beam on an instrument. The compact size and light weight of the system simplifies its utilization on various neutron instruments. The system has been successfully tested as a neutron polarizer on the triple-axis spectrometer (HB3) and the hybrid spectrometer (HYSPEC) at Oak Ridge National Laboratory. Over 70% {sup 3}He polarization was achieved and maintained during the test experiments. Over 90% neutron polarization and an average of 25% transmission for neutrons of 14.7 meV and 15 meV was also obtained.

  16. 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.

  17. 3He spin filters for spherical neutron polarimetry at the hot neutrons single crystal diffractometer POLI-HEiDi

    NASA Astrophysics Data System (ADS)

    Hutanu, V.; Meven, M.; Masalovich, S.; Heger, G.; Roth, G.

    2011-06-01

    3D vector polarisation analysis called also SNP (Spherical Neutron Polarimetry) is a powerful method for the detailed investigation of complex magnetic structures. The precise control of the incoming and scattered neutron polarisations is essential for this technique. Here we show an instrumental setup, that was recently implemented on the new single crystal diffractometer POLI-HEiDi at the FRM II for performing SNP experiments using two 3He spin filters for the production and for the analysis of the neutron polarisation. The design and optimisation procedure for the used spin filter cells are presented. Methods for in-situ measurements of the incoming polarisation as well as the particularities of the using two spin filters and corrections for the time dependent relaxation are discussed. Statistical precision of 1% has been achieved for the measurements of the polarisation matrix under the real experimental conditions using described cells and applying proposed correction method for the data.

  18. Test of a continuously polarized 3He neutron spin filter with NMR-based polarization inversion on a single-crystal diffractometer

    NASA Astrophysics Data System (ADS)

    Jones, G. L.; Dias, F.; Collett, B.; Chen, W. C.; Gentile, T. R.; Piccoli, P. M. B.; Miller, M. E.; Schultz, A. J.; Yan, H.; Tong, X.; Snow, W. M.; Lee, W. T.; Hoffmann, C.; Thomison, J.

    2006-11-01

    Spin filters based on the large spin dependence of the neutron absorption cross-section by 3He are currently being applied in neutron scattering. We report here the construction and test of a 3He neutron spin filter that incorporates (1) in situ continuous optical pumping to maximize the time-averaged polarization and maintain a stable 3He polarization during experiments, and (2) low-loss adiabatic-fast-passage inversion of the 3He polarization to eliminate the need for a neutron spin flipper. The device was successfully tested at the single-crystal diffractometer at the Intense-Pulsed Neutron Source, Argonne National Laboratory. This device can be used in measurements of static magnetic-materials as well as magnetic-relaxation phenomena with long relaxation times.

  19. Development of a 3He-hydraulic actuator for spin pump in superfluid 3He-A1

    NASA Astrophysics Data System (ADS)

    Yamaguchi, A.; Wada, M.; Tanaka, H.; Motoyama, G.; Sumiyama, A.; Aoki, Y.; Okuda, Y.; Murakawa, S.; Karaki, Y.; Kubota, M.; Kojima, H.

    2012-12-01

    The superfluid 3He A1 phase contains a spin-polarized condensate. This property allows novel superfluid spin current experiments. In the mechano-spin effect of the A1 phase a mechanically applied pressure gradient and a superleak-spin filter enable to directly boost spin polarization of 3He in a small chamber. Using a flexible membrane as an electrostatically actuated pump, we carried out such experiments and observed 50% enhancement of spin density. Here we report on a new 3He-hydraulic actuator for achieving greater enhancement of spin density. The actuator consists of two liquid 3He chambers located at a 4.2 K plate and in the interior of the cell. The pressure in the 4.2 K chamber is heater-controlled and it transmits a force onto a membrane in the cell. The motion of the membrane induces spin-polarized current into an accumulation chamber.

  20. 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.

  1. Neutron (3He) Spin Structure Functions at Low Q^2

    SciTech Connect

    Vincent Sulkosky

    2009-07-01

    Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility to provide a precise measurement of the $^{3}$He spin structure functions at low $Q^{2}$ from 0.02 to 0.3~[GeV$/c$]$^{2}$. A longitudinally-polarized electron beam was scattered from a longitudinally or transversely polarized $^{3}$He target. From these data, we have extracted moments of the neutron and $^{3}$He spin structure functions at very low momentum transfers. 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 first moments of the $g_1\\left(x,Q^{2}\\right)$ and $g_2\\left(x,Q^{2}\\right)$ structure functions are presented.

  2. 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.

  3. Quark-hadron duality in neutron (3He) spin structure.

    PubMed

    Solvignon, P; Liyanage, N; Chen, J-P; Choi, Seonho; Aniol, K; Averett, T; Boeglin, W; Camsonne, A; Cates, G D; Chang, C C; Chudakov, E; Craver, B; Cusanno, F; Deur, A; Dutta, D; Ent, R; Feuerbach, R; Frullani, S; Gao, H; Garibaldi, F; Gilman, R; Glashausser, C; Gorbenko, V; Hansen, O; Higinbotham, D W; Ibrahim, H; Jiang, X; Jones, M; Kelleher, A; Kelly, J; Keppel, C; Kim, W; Korsch, W; Kramer, K; Kumbartzki, G; Lerose, J J; Lindgren, R; Ma, B; Margaziotis, D J; Markowitz, P; McCormick, K; Meziani, Z-E; Michaels, R; Moffit, B; Monaghan, P; Munoz Camacho, C; Paschke, K; Reitz, B; Saha, A; Sheyor, R; Singh, J; Slifer, K; Sulkosky, V; Tobias, A; Urciuoli, G M; Wang, K; Wijesooriya, K; Wojtsekhowski, B; Woo, S; Yang, J-C; Zheng, X; Zhu, L

    2008-10-31

    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 3He 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 A1 in the resonance region for 3He and found no strong Q2 dependence above 2.2 (GeV/c);{2}.

  4. 3He spin exchange cells for magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Jacob, R. E.; Morgan, S. W.; Saam, B.

    2002-08-01

    We present a protocol for the consistent fabrication of glass cells to provide hyperpolarized (HP) 3He for pulmonary magnetic resonance imaging. The method for producing HP 3He is spin-exchange optical pumping. The valved cells must hold of order 1 atm[middle dot]L of gas at up to 15 atm pressure. Because characteristic spin-exchange times are several hours, the longitudinal nuclear relaxation time T1 for 3He must be several tens of hours and robust with respect to repeated refilling and repolarization. Collisions with the cell wall are a significant and often dominant cause of relaxation. Consistent control of wall relaxation through cell fabrication procedures has historically proven difficult. With the help of the discovery of an important mechanism for wall relaxation that involves magnetic surface sites in the glass, and with the further confirmation of the importance of Rb metal to long wall-relaxation times, we have developed a successful protocol for fabrication of 3He spin exchange cells from inexpensive and easily worked borosilicate (Pyrex) glass. The cells are prepared under vacuum using a high-vacuum oil-free turbomolecular pumping station, and they are sealed off under vacuum after [greater-than-or-equal, slanted]100 mg of distilled Rb metal is driven in. Filling of cells with the requisite 3He-N2 mixture is done on an entirely separate gas-handling system. Our cells can be refilled and the gas repolarized indefinitely with no significant change in their wall properties. Relaxation data are presented for about 30 cells; the majority of these reach a "40/40" benchmark: T1>40 h, and 3He polarizations reach or exceed 40%. Typical polarization times range from 12 to 20 h; 20% polarization can be achieved in 3-5 h.

  5. 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.

  6. 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.

  7. 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.

  8. 3He spin-dependent cross sections and sum rules.

    PubMed

    Slifer, K; Amarian, M; Auerbach, L; Averett, T; Berthot, J; Bertin, P; Bertozzi, B; Black, T; Brash, E; Brown, D; Burtin, E; Calarco, J; Cates, G; Chai, Z; Chen, J-P; Choi, Seonho; Chudakov, E; Ciofi Degli Atti, C; Cisbani, E; de Jager, C W; Deur, A; DiSalvo, R; Dieterich, S; Djawotho, P; Finn, M; Fissum, K; Fonvieille, H; Frullani, S; Gao, H; Gao, J; Garibaldi, F; Gasparian, A; Gilad, S; Gilman, R; Glamazdin, A; Glashausser, C; Glöckle, W; Golak, J; Goldberg, E; Gomez, J; Gorbenko, V; Hansen, J-O; Hersman, B; Holmes, R; Huber, G M; Hughes, E; Humensky, B; Incerti, S; Iodice, M; Jensen, S; Jiang, X; Jones, C; Jones, G; Jones, M; Jutier, C; Kamada, H; Ketikyan, A; Kominis, I; Korsch, W; Kramer, K; Kumar, K; Kumbartzki, G; Kuss, M; Lakuriqi, E; Laveissiere, G; Lerose, J J; Liang, M; Liyanage, N; Lolos, G; Malov, S; Marroncle, J; McCormick, K; McKeown, R D; Meziani, Z-E; Michaels, R; Mitchell, J; Nogga, A; Pace, E; Papandreou, Z; Pavlin, T; Petratos, G G; Pripstein, D; Prout, D; Ransome, R; Roblin, Y; Rowntree, D; Rvachev, M; Sabatié, F; Saha, A; Salmè, G; Scopetta, S; Skibiński, R; Souder, P; Saito, T; Strauch, S; Suleiman, R; Takahashi, K; Teijiro, S; Todor, L; Tsubota, H; Ueno, H; Urciuoli, G; Van der Meer, R; Vernin, P; Voskanian, H; Witała, H; Wojtsekhowski, B; Xiong, F; Xu, W; Yang, J-C; Zhang, B; Zolnierczuk, P

    2008-07-11

    We present a measurement of the spin-dependent cross sections for the 3He over -->(e over -->,e')X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1< or =Q2< or =0.9 GeV2. 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.

  9. 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

  10. Spin Pumping in Superfluid ^3He in High Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kojima, H.; Suzuki, K.; Aoki, Y.; Yamaguchi, A.; Ishimoto, H.

    2008-03-01

    The spin flow dynamics in superfluid ^3He A1 phase in magnetic field has been studied up to 13 tesla. The apparatus consists of a large reservoir of of A1 phase in which a small enclosed chamber with a built-in differential pressure sensor is immersed. The chamber is connected to the reservoir via a superleak channel. The chamber is fabricated from Macor parts such that the residual heat leak is much reduced from those in our experiments. Our focus is on the measurement of relaxation of the induced pressure subsequent to either magnetically induced spin-polarized superflow or by electrostatic spin pumping. In general, both methods of measurement show that the relaxation time (τ) of the induced pressure tends to vanish smoothly as the transition temperature Tc2 is approached. However, the observed dependence of τ on magnetic field is different. The measured τ by the field gradient method continues to increase up to 8 tesla. On the other hand, τ measured by the spin pumping method tends to saturate to a constant between 5 and 13 tesla. The discrepancy is unexpected and not yet understood.

  11. 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.

  12. ^3He Polarization by Rb Spin Exchange in a Multistage System

    NASA Astrophysics Data System (ADS)

    Coulter, K. P.; Chupp, T. E.; Smith, T. B.; Welsh, R. C.; Zerger, J. N.

    1999-10-01

    Polarization of ^3He by spin exchange with optically pumped Rb has benefited greatly from the use of high powered laser diode arrays. Efficient use of these lasers requires operation of cells with high ^3He densities to match better the pressure broadened Rb absorption line to the wide laser spectral profile. However, lower delivery pressures are often required. For example, for low energy neutron spin filters the optimum ^3He thickness (for practical polarizations) would produce impractically thin cells. A multistage system is practical for applications requiring high ^3He polarization delivered at variable pressure because the optical pumping stage can be separated from the delivery/refilling stages. Additionally, operation can be improved by choosing the appropriate glass for each stage. We have constructed a multistage system that consists of a 70 cc pump cell (Corning 7056 glass), a transition region (Pyrex Glass), and a 350 cc receiving cell (Cs-coated Fused Silica). The cells are connected using commercial Viton-rubber o-ring sealed Pyrex glass valves and ball and socket joints. The transition region is connected to a vacuum pump and gas fill system so that cells may be refilled in situ. Both pump cells and receiving cells have exhibited intrinsic ^3He relaxation times of >35 hours. We will report on tests of this prototype system.

  13. 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.

  14. 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.

  15. Recent advances in spin-exchange pumped polarized 3He target technology

    NASA Astrophysics Data System (ADS)

    Smith, T. B.; Chupp, T. E.; Coulter, K. P.; Welsh, R. C.

    1998-02-01

    We have produced long lifetime 3He spin-exchange cells from Corning 7056 glass. The lifetimes of single cells have approached the 3He 3He bulk-limited lifetime (250 h at a density of 8 × 10 19 cm -3, (3 amagats)). Corning 7056 glass has the advantage of being a much easier glass for the glassblower to work, allowing for more complex cell designs. In our experiments at Michigan and at SLAC, we have implemented laser diode arrays for spin-exchange optical pumping. In particular, for experiment E154 at SLAC, we achieved high polarizations in high-density 3He targets using laser diode arrays.

  16. Bounds on New Spin Dependent Forces Between Neutrons Using a ^3He / ^129Xe Zeeman Maser

    NASA Astrophysics Data System (ADS)

    Glenday, Alex; Cramer, Claire; Phillips, David F.; Walsworth, Ronald L.

    2008-05-01

    Searches for new spin dependent macroscopic forces place bounds on physics beyond the Standard Model, such as Lorentz symmetry violation and existence of new particles like the axion. We report the first experimental limits on new spin dependent macroscopic forces between neutron spins. We measure the nuclear Zeeman frequencies of a ^3He / ^129Xe maser while we modulate the nuclear spin polarization of ^3He in a separate glass cell. We place limits on the coupling strength of dipole potentials mediated by axion-like particles (gpgp) at the 5.5x10-6 level for interactions at ranges longer than 40 cm.

  17. 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.

  18. Longitudinal and transverse spin diffusion in3He-4He solutions in a strong magnetic field

    NASA Astrophysics Data System (ADS)

    Ager, J. H.; Child, A.; König, R.; Owers-Bradley, J. R.; Bowley, R. M.

    1995-06-01

    Using pulsed NMR techniques, we have measured spin diffusion in3He-3He solutions with3He concentrations of 0.05%, 0.1%, 0.46%, 1.0%, 3.8% and 6.4% in a magnetic field of 8.8 Tesla for a temperature range 11 mK⩽ T ⩽ 200 mK. We observe that the temperature dependence of the transverse spin diffusion coefficient D1 deviates from that expected for an unpolarized Fermi liquid in the degenerate region in the 1.0%, 3.8% and 6.4% solutions. Moreover, by measuring both longitudinal and transverse spin diffusion coefficients in the 6.4%-mixture, we have verified experimentally the difference between them, and provided direct evidence for a field-induced anisotropy in spin diffusion. The results from the 0.05% and 0.1% solutions show agreement with the theory of Jeon and Mullin; however, no deviation of D1 from that expected in an unpolarized mixture was observed because the3He is not in the degenerate regime for these very dilute systems for the temperatures we could achieve. The analysis of our measurements in terms of the Leggett-Rice equations also yields values for the spin rotation parameter μM0. Using our results along with previous measurements at various3He concentrations, we deduce a value for the s-wave quasiparticle scattering length of a=-0.88 ± 0.05 Å.

  19. 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.

  20. 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.

  1. Orbital glass and spin glass states of 3He-A in aerogel

    NASA Astrophysics Data System (ADS)

    Dmitriev, V. V.; Krasnikhin, D. A.; Mulders, N.; Senin, A. A.; Volovik, G. E.; Yudin, A. N.

    2010-06-01

    Glass states of superfluid A-like phase of 3He in aerogel induced by random orientations of aerogel strands are investigated theoretically and experimentally. In anisotropic aerogel with stretching deformation two glass phases are observed. Both phases represent the anisotropic glass of the orbital ferromagnetic vector Ηthe orbital glass (OG). The phases differ by the spin structure: the spin nematic vector hat d can be either in the ordered spin nematic (SN) state or in the disordered spin-glass (SG) state. The first phase (OG-SN) is formed under conventional cooling from normal 3He. The second phase (OG-SG) is metastable, being obtained by cooling through the superfluid transition temperature, when large enough resonant continuous radio-frequency excitation is applied. NMR signature of different phases allows us to measure the parameter of the global anisotropy of the orbital glass induced by deformation.

  2. Magnetic field dependent transverse spin diffusion constant in 3He- 4He solutions

    NASA Astrophysics Data System (ADS)

    Owers-Bradley, J. R.; Child, A.; Bowley, R. M.

    1994-02-01

    The transverse spin diffusion constant of 3He- 4He solutions has been measured by pulsed nmr in magnetic fields of 2.18T and 8.8T for 3He concentrations of 0.5%, 1.0% and 3.8%. For the higher concentrations the diffusion constant at 8.8T is smaller than at 2.18T for the lowest temperatures used. The effect is largest for the 3.8% solution (a reduction by 1.7 at 15mK), but is too small to be measurable for the 0.5% solution. These results are compared to measurements of Candela et al. for pure 3He, and to the theory of Jeon and Mullin.

  3. Spin correlations in quasi-elastic electron scattering from a (3)He internal target

    NASA Astrophysics Data System (ADS)

    Six, R. Edward, III

    The measurement of spin observables in the 3He-> (e->,e' ,d) and 3He-> (e->,e' ,p) reactions have been carried out at the Internal Target Facility of the Dutch National Institute for Nuclear and High Energy Physics (NIKHEF) in Amsterdam, The Netherlands, with a 720-MeV stored electron beam having a longitudinal polarization of 65% and an average current of 80 mA. This was the first measurement of the spin correlation parameters for the reaction 3He-> (e->,e' ,d) . The average target polarization was 45% with a thickness of 5 × 1014 atoms/cm2. The scattered electrons were detected in a large-acceptance, nonfocusing magnetic spectrometer located at a central angle of 40°. The knockout hadrons were detected in a non-magnetic detector located at a central angle of -56°. The central positions of the detectors correspond to quasi-elastic kinematics. The asymmetries A'x and A'x provide information on small components of the 3He ground-state wave function and on the isoscalar/isovector structure of the nuclear electromagnetic current. The results are compared with model calculations.

  4. 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.

  5. Spin nutation in the quasi-isotropic A-like superfluid phase of {sup 3}He

    SciTech Connect

    Fomin, I. A.

    2006-06-15

    The order parameter of the quasi-isotropic A-like superfluid phase of {sup 3}He has been reduced to a simple form. The frequencies of the spatially homogeneous oscillations of the spin and the spin part of the order parameter of this phase have been obtained taking into account the anisotropy of its magnetic susceptibility. It has been shown that the anisotropy of susceptibility strongly affects the low-frequency oscillation mode, which is similar to the nutation of an asymmetric top. The possibility of observing this mode using the NMR method is discussed.

  6. {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.

  7. Nuclear Spin Relaxation in Glass States of 3He-A in Stretched Aerogel

    NASA Astrophysics Data System (ADS)

    Dmitriev, V. V.; Krasnikhin, D. A.; Mulders, N.; Senin, A. A.; Yudin, A. N.

    2011-02-01

    We present results of pulse NMR investigations of superfluid A-like phase of 3He in stretched aerogel. In this case we have anisotropic orbital glass (OG) with two possible types of ordering in spin space—ordered spin nematic (OG-SN) or disordered spin glass (OG-SG) states. It was found that longitudinal relaxation of magnetization is non-exponential in both states and depends on temperature and on inhomogeneity of external steady magnetic field. At the same conditions the relaxation in OG-SG state is more rapid than in OG-SN state. For transverse orientation of the magnetic field relative to anisotropy axis the duration of free induction decay signal was longer than in normal phase. It may be explained by formation of coherently precessing spin state.

  8. Low Q^2 measurements of the neutron and 3He spin structure

    SciTech Connect

    Vincent Sulkosky

    2006-10-22

    Thomas Jefferson National Accelerator Facility experiment E97-110 was performed to provide a precise measurement of the extended Gerasimov-Drell-Hearn integral and of moments of the neutron and of the {sup 3}He spin structure functions. The momentum transfer range 0.02 < 0.3 (GeV)/c{sup 2} will allow us to test predictions of Chiral Perturbation Theory, and check the GDH sum rule by extrapolating the integral to the real photon point. The data have been taken in Hall A using a highly polarized electron beam and a polarized {sup 3}He target. The status of the data analysis is discussed, and preliminary results are shown.

  9. Twenty Years of Magnon Bose Condensation and Spin Current Superfluidity in 3He-B

    NASA Astrophysics Data System (ADS)

    Volovik, G. E.

    2008-12-01

    20 years ago a new quantum state of matter was discovered and identified (Borovik-Romanov et al. in JETP Lett. 40:1033, 1984; 45:124, 1987; 47:478, 1988; Fomin in JETP Lett. 40:1037, 1984; Borovik-Romanov et al. in Sov. Phys. JETP 61:1199, 1985; Fomin in Sov. Phys. JETP 61:1207, 1985; Bunkov et al. in JETP Lett. 43:168, 1986). The observed dynamic quantum state of spin precession in superfluid 3He-B bears the properties of spin current superfluidity, Bose condensation of spin waves—magnons, off-diagonal long-range order and related phenomena of quantum coherence.

  10. 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

  11. Equal-spin pairing state of superfluid {sup 3}He in aerogel

    SciTech Connect

    Aoyama, Kazushi; Ikeda, Ryusuke

    2005-07-01

    The equal-spin pairing state, the so-called A-like phase, of superfluid {sup 3}He in aerogels is studied theoretically in the Ginzburg-Landau region by examining thermodynamics, and the resulting equilibrium phase diagram is mapped out. We find that the ABM pairing state with presumably quasi-long-ranged superfluid order has a lower free energy than the planar and 'robust' states and is the best candidate of the A-like phase with a strange lowering of the polycritical point observed experimentally.

  12. Q2 evolution of the neutron spin structure moments using a 3He target.

    PubMed

    Amarian, M; Auerbach, L; Averett, T; Berthot, J; Bertin, P; Bertozzi, B; Black, T; Brash, E; Brown, D; Burtin, E; Calarco, J; Cates, G; Chai, Z; Chen, J-P; Choi, Seonho; Chudakov, E; Cisbani, E; De Jager, C W; Deur, A; DiSalvo, R; Dieterich, S; Djawotho, P; Finn, M; Fissum, K; Fonvieille, H; Frullani, S; Gao, H; Gao, J; Garibaldi, F; Gasparian, A; Gilad, S; Gilman, R; Glamazdin, A; Glashausser, C; Goldberg, E; Gomez, J; Gorbenko, V; Hansen, J-O; Hersman, B; Holmes, R; Huber, G M; Hughes, E; Humensky, B; Incerti, S; Iodice, M; Jensen, S; Jiang, X; Jones, C; Jones, G; Jones, M; Jutier, C; Ketikyan, A; Kominis, I; Korsch, W; Kramer, K; Kumar, K; Kumbartzki, G; Kuss, M; Lakuriqi, E; Laveissiere, G; Lerose, J; Liang, M; Liyanage, N; Lolos, G; Malov, S; Marroncle, J; McCormick, K; McKeown, R; Meziani, Z-E; Michaels, R; Mitchell, J; Papandreou, Z; Pavlin, T; Petratos, G G; Pripstein, D; Prout, D; Ransome, R; Roblin, Y; Rowntree, D; Rvachev, M; Sabatie, F; Saha, A; Slifer, K; Souder, P; Saito, T; Strauch, S; Suleiman, R; Takahashi, K; Teijiro, S; Todor, L; Tsubota, H; Ueno, H; Urciuoli, G; Van Der Meer, R; Vernin, P; Voskanian, H; Wojtsekhowski, B; Xiong, F; Xu, W; Yang, J-C; Zhang, B; Zolnierczuk, P

    2004-01-16

    We have measured the spin structure functions g(1) and g(2) of 3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.058 GeV off a polarized 3He target at a 15.5 degrees scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q2 evolution of Gamma(1)(Q2)= integral (1)(0)g(1)(x,Q2)dx, Gamma(2)(Q2)= integral (1)(0)g(2)(x,Q2)dx, and d(2)(Q2)= integral (1)(0)x(2)[2g(1)(x,Q2)+3g(2)(x,Q2)]dx for the neutron in the range 0.1< or =Q2< or =0.9 GeV2 with good precision. Gamma(1)(Q2) displays a smooth variation from high to low Q2. The Burkhardt-Cottingham sum rule holds within uncertainties and d(2) is nonzero over the measured range.

  13. Anisotropic strong-coupling effects on superfluid 3He in aerogels: Conventional spin-fluctuation approach

    NASA Astrophysics Data System (ADS)

    Ikeda, Ryusuke

    2015-05-01

    Motivated by recent experiments on liquid 3He reporting emergence of novel superfluid phases in globally anisotropic aerogels, our previous theory on superfluid 3He in globally anisotropic aerogels is extended to incorporate the effects of anisotropy of the quasiparticle scattering cross section on the strong-coupling (SC) contributions to the Ginzburg-Landau (GL) free energy on the basis of the spin-fluctuation (paramagnon) approach to the SC contributions developed by Brinkman et al. [Phys. Rev. A 10, 2386 (1974), 10.1103/PhysRevA.10.2386]. In the globally isotropic case, impurity effects on the SC correction destabilize the A phase even at higher pressures of about 30 bar and make the B phase the only state in equilibrium, while SC contributions accompanied by a global stretched anisotropy to the GL quartic terms generally tend to broaden the stability region of the A phase compared with that of the B phase. In particular, in contrast to the cases in bulk and in the isotropic aerogel, the SC corrections to the GL quadratic terms are not negligible in the globally anisotropic case but may change the sign of the apparent anisotropy depending on the magnitude of the frequency cutoff of the normal paramagnon propagator. Based on this sign change of the apparent anisotropy, we discuss different strange observations on superfluid 3He in porous media such as the disappearance of the polar superfluid phase at higher pressures seen in nematically ordered aerogels and the absence of B and A phases with planar l ̂ vector in a stretched aerogel.

  14. Anomalous nuclear spin-lattice relaxation of 3He in contact with ordered Al2O3 aerogel

    NASA Astrophysics Data System (ADS)

    Alakshin, E. M.; Zakharov, M. Yu.; Klochkov, A. V.; Kuzmin, V. V.; Safiullin, K. R.; Stanislavovas, A. A.; Tagirov, M. S.

    2016-09-01

    Spin-lattice relaxation of 3He in contact with the ordered Al2O3 fiber aerogel has been studied at the temperature of 1.6 K in fields of 0.1-0.5 T by the pulsed nuclear magnetic resonance (NMR) method. An additional mechanism of the relaxation of 3He in aerogels is found and it is shown that this relaxation mechanism is not associated with the adsorbed layer. A hypothesis about the influence of intrinsic paramagnetic centers on the relaxation of gaseous 3He is proposed.

  15. Compact photonic spin filters

    NASA Astrophysics Data System (ADS)

    Ke, Yougang; Liu, Zhenxing; Liu, Yachao; Zhou, Junxiao; Shu, Weixing; Luo, Hailu; Wen, Shuangchun

    2016-10-01

    In this letter, we propose and experimentally demonstrate a compact photonic spin filter formed by integrating a Pancharatnam-Berry phase lens (focal length of ±f ) into a conventional plano-concave lens (focal length of -f). By choosing the input port of the filter, photons with a desired spin state, such as the right-handed component or the left-handed one, propagate alone its original propagation direction, while the unwanted spin component is quickly diverged after passing through the filter. One application of the filter, sorting the spin-dependent components of vector vortex beams on higher-order Poincaré sphere, is also demonstrated. Our scheme provides a simple method to manipulate light, and thereby enables potential applications for photonic devices.

  16. Non-magnetic flexible heaters for spin-exchange optical pumping of 3He and other applications

    NASA Astrophysics Data System (ADS)

    Ino, T.; Hayashida, H.; Kira, H.; Oku, T.; Sakai, K.

    2016-11-01

    Spin polarized 3He gas is currently widely used in various scientific fields and in medical diagnosis applications. The spin polarization of 3He nuclei can be achieved by spin-exchange optical pumping (SEOP). In SEOP, the 3He gas is enclosed in a glass cell together with alkali metals and is then heated to maintain the alkali metal vapor pressures at the appropriate levels. However, polarized 3He gas is highly sensitive to any inhomogeneity in its magnetic field, and any small field gradients caused by the heaters may cause degradation of the 3He polarization. To overcome this conflict between the heating process and the magnetic field, we have developed electrical heaters that essentially cause no magnetic fields. These heaters are thin and are flexible enough to be bent to within a radius of a few centimeters. These carefully designed heater elements and a double layer structure effectively eliminate magnetic field generation. The heaters were originally developed for SEOP applications, but can also be applied to other processes that need to avoid unwanted magnetic fields.

  17. Increasing the pump-up rate to polarize 3He gas using spin-exchange optical pumping method

    NASA Astrophysics Data System (ADS)

    Lee, Wai Tung; Tong, Xin; Rich, Dennis; Liu, Yun; Fleenor, Michael; Ismaili, Akbar; Pierce, Joshua; Hagen, Mark; Dadras, Jonny; Robertson, J. Lee

    2009-09-01

    In recent years, polarized 3He gas has increasingly been used as neutron polarizers and polarization analyzers. Two of the leading methods to polarize the 3He gas are the spin-exchange optical pumping (SEOP) method and the meta-stable exchange optical pumping (MEOP) method. At present, the SEOP setup is comparatively compact due to the fact that it does not require the sophisticated compressor system used in the MEOP method. The temperature and the laser power available determine the speed, at which the SEOP method polarizes the 3He gas. For the quantity of gas typically used in neutron scattering work, this speed is independent of the quantity of the gas required, whereas the polarizing time using the MEOP method is proportional to the quantity of gas required. Currently, using the SEOP method to polarize several bar-liters of 3He to 70% polarization would require 20-40 h. This is an order of magnitude longer than the MEOP method for the same quantity of gas and polarization. It would therefore be advantageous to speed up the SEOP process. In this article, we analyze the requirements for temperature, laser power, and the type of alkali used in order to shorten the time required to polarize 3He gas using the SEOP method.

  18. 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.

  19. 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.

  20. Precision measurement of the spin-dependent asymmetry in the threshold region of 3He(e, e').

    PubMed

    Xiong, F; Dutta, D; Xu, W; Anderson, B; Auberbach, L; Averett, T; Bertozzi, W; Black, T; Calarco, J; Cardman, L; Cates, G D; Chai, Z W; Chen, J P; Choi, S; Chudakov, E; Churchwell, S; Corrado, G S; Crawford, C; Dale, D; Deur, A; Djawotho, P; Filippone, B W; Finn, J M; Gao, H; Gilman, R; Glamazdin, A V; Glashausser, C; Glöckle, W; Golak, J; Gomez, J; Gorbenko, V G; Hansen, J O; Hersman, F W; Higinbotham, D W; Holmes, R; Howell, C R; Hughes, E; Humensky, B; Incerti, S; de Jager, C W; Jensen, J S; Jiang, X; Jones, C E; Jones, M; Kahl, R; Kamada, H; Kievsky, A; Kominis, I; Korsch, W; Kramer, K; Kumbartzki, G; Kuss, M; Lakuriqi, E; Liang, M; Liyanage, N; LeRose, J; Malov, S; Margaziotis, D J; Martin, J W; McCormick, K; McKeown, R D; McIlhany, K; Meziani, Z E; Michaels, R; Miller, G W; Pace, E; Pavlin, T; Petratos, G G; Pomatsalyuk, R I; Pripstein, D; Prout, D; Ransome, R D; Roblin, Y; Rvachev, M; Saha, A; Salmè, G; Schnee, M; Shin, T; Slifer, K; Souder, P A; Strauch, S; Suleiman, R; Sutter, M; Tipton, B; Todor, L; Viviani, M; Vlahovic, B; Watson, J; Williamson, C F; Witała, H; Wojtsekhowski, B; Yeh, J; Zołnierczuk, P

    2001-12-10

    We present the first precision measurement of the spin-dependent asymmetry in the threshold region of 3He(e,e') at Q2 values of 0.1 and 0.2 (GeV/c)2. The agreement between the data and nonrelativistic Faddeev calculations which include both final-state interactions and meson-exchange current effects is very good at Q2 = 0.1 (GeV/c)2, while a small discrepancy at Q2 = 0.2 (GeV/c)2 is observed.

  1. Spin-polarized 3He in a density-functional frame

    NASA Astrophysics Data System (ADS)

    Gatica, S. M.; Hernández, E. S.; Navarro, J.

    1998-11-01

    The properties of spin-polarized liquid helium are analyzed in a density-functional framework. It is shown that the BHN functional [M. Barranco et al., Phys. Rev. B 54, 7394 (1996)] designed to describe the thermodynamics and the response of the unpolarized liquid also reproduces reasonably well recent experimental results at low magnetization. In particular, the present description reproduces the magnetic field data for the weakly polarized liquid, and is also consistent with the existence of a near-metamagnetic transition at a polarization close to 0.2. We indicate the various difficulties associated with the extension of the current scenario to highly and fully magnetized systems.

  2. Spin Filtering in Storage Rings

    NASA Astrophysics Data System (ADS)

    Nikolaev, N. N.; Pavlov, F. F.

    The spin filtering in storage rings is based on a multiple passage of a stored beam through a polarized internal gas target. Apart from the polarization by the spin-dependent transmission, a unique geometrical feature of interaction with the target in such a filtering process, pointed out by H.O. Meyer,1 is a scattering of stored particles within the beam. A rotation of the spin in the scattering process affects the polarization buildup. We derive here a quantum-mechanical evolution equation for the spin-density matrix of a stored beam which incorporates the scattering within the beam. We show how the interplay of the transmission and scattering within the beam changes from polarized electrons to polarized protons in the atomic target. After discussions of the FILTEX results on the filtering of stored protons,2 we comment on the strategy of spin filtering of antiprotons for the PAX experiment at GSI FAIR.3.

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

    DOE PAGES

    Allada, K.; Zhao, Y. X.; Aniol, K.; ...

    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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. An analogy between effects of ultra-low doses of biologically active substances on biological objects and properties of spin supercurrents in superfluid 3He-B.

    PubMed

    Boldyreva, Liudmila B

    2011-07-01

    The effects of ultra-low doses (ULDs) of biologically active substances (BASs) (with concentrations of 10(-13)M or lower) on biological objects (BOs), such as cells, organisms, etc., and the properties of spin supercurrents in superfluid (3)He-B are discussed. It is shown that the effects of ULDs of BASs on biologic objects can be specified by the same set of physical characteristics and described by the same mathematical relations as those used for the specification and description of the properties of spin supercurrents between spin structures in superfluid (3)He-B. This is based on the up-to-date physical concepts: 1) the physical vacuum has the properties of superfluid (3)He-B; 2) all quantum entities (hence, the BAS and the BO, which consist of such entities) produce spin structures in the physical vacuum. The photon being a quantum entity, the features of the effects of low-intensity electromagnetic radiation on BOs can be explained using the same approach.

  9. 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.

  10. Single/Double-Spin Asymmetry Measurements of Semi-Inclusive Pion Electroproduction on a Transversely Polarized 3He Target through Deep Inelastic Scattering

    SciTech Connect

    Xin Qian

    2012-06-01

    Parton distribution functions, which represent the flavor and spin structure of the nucleon, provide invaluable information in illuminating quantum chromodynamics in the confinement region. Among various processes that measure such parton distribution functions, semi-inclusive deep inelastic scattering is regarded as one of the golden channels to access transverse momentum dependent parton distribution functions, which provide a 3-D view of the nucleon structure in momentum space. The Jefferson Lab experiment E06-010 focuses on measuring the target single and double spin asymmetries in the 3He(e, e'pi+,-)X reaction with a transversely polarized 3He target in Hall A with a 5.89 GeV electron beam. A leading pion and the scattered electron are detected in coincidence by the left High-Resolution Spectrometer at 16{sup o} and the BigBite spectrometer at 30{sup o} beam right, respectively. The kinematic coverage concentrates in the valence quark region, x {approx} 0.1-0.4, at Q2 {approx}1-3 Gev{sub 2}. The Collins and Sivers asymmetries of 3He and neutron are extracted. In this review, an overview of the experiment and the final results are presented. Furthermore, an upcoming 12-GeV program with a large acceptance solenoidal device and the future possibilities at an electron-ion collider are discussed.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Effects of surface roughness on non-uniform phases of superfluid 3He and spin-triplet models for Sr2RuO4

    NASA Astrophysics Data System (ADS)

    Vorontsov, Anton; Sauls, James

    2014-03-01

    We present theoretical and computational results for the spectrum of surface bound states of confined superfluid 3He and spin-triplet, odd-parity pairing theories of Sr2RuO4. The surface states, despite being related to the topological structure of the condensed state, are sensitive to surface disorder. We investigate effects of surface roughness on the physical properties of the boundary layer of several coherence lengths. We find that for confined 3He-A or chiral phases proposed for Sr2RuO4 the spatial profile of the edge current is significantly modified for atomically rough surfaces compared to that for specular surfaces. The boundary effect is strongly reflected in the ground-state angular momentum generated by the edge states. In thin films of superfluid 3He with rough surfaces the effect of surface scattering is expected to be even more important since surface states dominate the thermodynamic properties. For specular boundaries we predicted new phases with spontaneously broken time-reversal or translational symmetries should appear in films of D ~ 10ξ0 . We report results for the phase diagram for specular, diffuse and maximal pair-breaking resulting from retro-reflecting boundaries. Supported by NSF Grants DMR-0954342 and DMR-1106315.

  16. Application of a portable 3He-based polarization insert at a time-of-flight neutron reflectometer

    NASA Astrophysics Data System (ADS)

    Kreuzpaintner, Wolfgang; Masalovich, Sergey; Moulin, Jean-François; Wiedemann, Birgit; Ye, Jingfan; Mayr, Sina; Paul, Amitesh; Haese, Martin; Pomm, Matthias; Böni, Peter

    2017-03-01

    The suitability of a transportable 3He-spin filter as temporary broadband polarizer for a Time-of-Flight neutron reflectometer is demonstrated. A simple two-wavelength method for characterisation of a 3He-spin filter is proposed, which can be applied even if the absolute transmittance of the 3He-spin filter cannot be accurately determined. We demonstrate the data treatment procedure for extracting the spin-up and spin-down neutron reflectivity from measurements obtained with a time dependent 3He polarization. The extraction of a very weak magnetic signal from reflectivity data, measured on the in-situ grown magnetic heterostructure Fe1nm /Cu20nm /Sisubstrate in an externally applied magnetic field of 30 mT is presented and compared to similar measurements on the growth stage Cu20nm /Sisubstrate of the very same sample, which does not yet contain any magnetic material.

  17. 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

    2012-02-03

    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.

  18. 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.

  19. Spin Filtering Studies at COSY and AD

    NASA Astrophysics Data System (ADS)

    Nass, Alexander

    2009-08-01

    The high physics potential of experiments with stored high-energy polarized antiprotons led to the proposal of PAX (Polarized Antiproton eXperiment) [1] 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/Jülich) as well as antiprotons (at AD/CERN) will be carried out to test the principle and measure p¯p⃗ and p¯d⃗ cross sections. A polarized internal gas target (PIT) with surrounding Silicon detectors immersed into a low-β section has to be set up.

  20. 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.

  1. Vortices in rotating superfluid 3He.

    PubMed

    Lounasmaa, O V; Thuneberg, E

    1999-07-06

    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.

  2. Development of a compact in situ polarized ³He neutron spin filter at Oak Ridge National Laboratory.

    PubMed

    Jiang, C Y; Tong, X; Brown, D R; Chi, S; Christianson, A D; Kadron, B J; Robertson, J L; Winn, B L

    2014-07-01

    We constructed a compact in situ polarized (3)He neutron spin filter based on spin-exchange optical pumping which is capable of continuous pumping of the (3)He gas while the system is in place in the neutron beam on an instrument. The compact size and light weight of the system simplifies its utilization on various neutron instruments. The system has been successfully tested as a neutron polarizer on the triple-axis spectrometer (HB3) and the hybrid spectrometer (HYSPEC) at Oak Ridge National Laboratory. Over 70% (3)He polarization was achieved and maintained during the test experiments. Over 90% neutron polarization and an average of 25% transmission for neutrons of 14.7 meV and 15 meV was also obtained.

  3. 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.

  4. 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.

  5. Experiments on polarization-dependent transport in 3He systems

    NASA Astrophysics Data System (ADS)

    Candela, D.; McAllaster, D. R.; Wei, L.-J.; Kalechofsy, N.

    1994-03-01

    Spin and momentum transport experiments are described for very dilute 3He- 4He mixtures and pure 3He brute-force polarized by a static field. Spin diffusion and rotation were observed in very dilute mixtures using a spin-wave resonance technique, and the viscosity increase due to polarization was observed using a vibrating wire. The mixture results are all well fit by the recent kinetic-equation calculations of Mullin and Jeon. Spin echoes were used to study transverse spin diffusion in pure 3He, providing the first clear evidence for polarization-induced relaxation-time anisotropy in a degenerate Fermi liquid.

  6. Fully magnetic manganite spin filter tunnel junctions

    NASA Astrophysics Data System (ADS)

    Prasad, Bhagwati; Blamire, Mark G.

    2016-09-01

    In this paper we demonstrate spintronic devices which combine magnetic tunnel junctions with a spin-filtering tunnel barrier. These consist of an ultrathin ferromagnetic insulating barrier, Sm0.75Sr0.25MnO3, sandwiched between two ferromagnetic half-metallic manganite electrodes, La0.7Sr0.3MnO3 and La0.7Ca0.3MnO3, in a nanopillar structure. Depending on the relative magnetic configurations of barrier and electrode layers, three resistance states are well defined, which therefore represent a potential three-state memory concept. These results open the way for the development of spintronic devices by exploiting the many degrees of freedom of perovskite manganite heterostructure systems.

  7. Vectorial spin polarization detection in multichannel spin-resolved photoemission spectroscopy using an Ir(001) imaging spin filter

    NASA Astrophysics Data System (ADS)

    Schaefer, Erik D.; Borek, Stephan; Braun, Jürgen; Minár, Ján; Ebert, Hubert; Medjanik, Katerina; Kutnyakhov, Dmytro; Schönhense, Gerd; Elmers, Hans-Joachim

    2017-03-01

    We report on spin- and angular-resolved photoemission spectroscopy using a high-resolution imaging spin filter based on a large Ir(001) crystal enhancing the effective figure of merit for spin detection by a factor of over 103 compared to standard single-channel detectors. Furthermore, we review the spin filter preparation and its lifetime. The spin filter efficiency is mapped on a broad range of scattering energies and azimuthal angles. Large spin filter efficiencies are observed for the spin component perpendicular as well as parallel to the scattering plane depending on the azimuthal orientation of the spin filter crystal. A spin rotator capable of manipulating the spin direction prior to detection complements the measurement of three observables, thus allowing for a derivation of all three components of the spin polarization vector in multichannel spin polarimetry. The experimental results nicely agree with spin-polarized low-energy electron diffraction calculations based on a fully relativistic multiple scattering method in the framework of spin-polarized density functional theory.

  8. 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.

  9. 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.

  10. 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.

  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. Polarization of stored beam by spin-filtering at COSY

    NASA Astrophysics Data System (ADS)

    Ciullo, G.

    2014-01-01

    In the challenging aim to achieve polarized antiproton, the PAX collaboration performed dedicated measurements of the spin-dependent polarizing cross section for p- p scattering at COSY. The result, under a very nice control of the process, agrees with the theoretical previsions, and confirms the pursuability of the spin-filtering for polarizing antiprotons.

  13. 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).

  14. Nuclear magnetic relaxation of3He gas. I. Pure3He

    NASA Astrophysics Data System (ADS)

    Lusher, C. P.; Secca, M. F.; Richards, M. G.

    1988-07-01

    Longitudinal relaxation times T 1 have been measured in3He gas, using pulsed NMR, for number densities between 3 × 1023 and 6 × 1025 spins m-3 and temperatures between 0.6 and 15 K. Relaxation takes place on or near the walls of the Pyrex sample cells and measurements of T 1 give information about the surface phases. A cryogenic wall coating of solid molecular hydrogen was found to delay the formation of a3He monolayer on cooling, and T 1 measurements were consistent with a binding energy of ˜13 K for a3He atom to a hydrogen surface. At temperatures below ˜2 K a completed3He monolayer forms on the H2 coating. No variation of the areal density of monolayer completion with bulk number density at fixed temperature could be observed and the completed3He monolayer is thought to be a dense fluid. Baking the Pyrex sample cells under vacuum and using an rf discharge in3He gas to clean the walls before sealing in the sample gas were found to increase the observed T1's by up to three orders of magnitude. Once a3He monolayer has formed on the H2 surface in these cleaned, sealed cells, the dipolar interaction between adsorbed spins is thought to be the dominant source of longitudinal relaxation. The data are consistent with a dipolar relaxation model with a correlation time of ˜2 × 10-9 sec. This time is long compared to the value of 10-11 or 10-12 sec in the 3D fluid. This suggests that if the surface phase is a 2D fluid and the dipolar mechanism is indeed the dominant one, then the atoms in the 2D fluid are less mobile than in three dimensions. This is consistent with recent susceptibility measurements.

  15. Perfect spin filtering effect in ultrasmall helical zigzag graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Zhang, Zi-Yue

    2017-02-01

    The spin-polarized transport properties of helical zigzag graphene nanoribbons (ZGNRs) are investigated by first-principles calculations. It is found that although all helical ZGNRs have similar density of states and edge states, they show obviously different transport characteristics depending on the curling manners. ZGNRs curled along zigzag orientation exhibit perfect spin filtering effect with a large spin-split gap near the Fermi level, while ZGNRs curled along armchair orientation behave as conventional conductors for both two spin channels. The spin filtering effect will be weakened with the increase of either ribbon width or curling diameter. The results suggest that ultrasmall helical ZGNRs have important potential applications in spintronics and flexible electronics.

  16. Nanopillar spin filter tunnel junctions with manganite barriers.

    PubMed

    Prasad, Bhagwati; Egilmez, Mehmet; Schoofs, Frank; Fix, Thomas; Vickers, Mary E; Zhang, Wenrui; Jian, Jie; Wang, Haiyan; Blamire, Mark G

    2014-05-14

    The potential of a manganite ferromagnetic insulator in the field of spin-filtering has been demonstrated. For this, an ultrathin film of Sm0.75Sr0.25MnO3 is integrated as a barrier in an epitaxial oxide nanopillar tunnel junction and a high spin polarization of up to 75% at 5 K has been achieved. A large zero-bias anomaly observed in the dynamic conductance at low temperatures is explained in terms of the Kondo scattering model. In addition, a decrease in spin polarization at low bias and hysteretic magneto-resistance at low temperatures are reported. The results open up new possibilities for spin-electronics and suggest exploration of other manganites-based materials for the room temperature spin-filter applications.

  17. 3He on preplated graphite

    NASA Astrophysics Data System (ADS)

    Gordillo, M. C.; Boronat, J.

    2016-10-01

    By using the diffusion Monte Carlo method, we obtained the full phase diagram of 3He on top of graphite preplated with a solid layer of 4He. All the 4He atoms of the substrate were explicitly considered and allowed to move during the simulation. We found that the ground state is a liquid of density 0.007 ±0.001 Å-2, in good agreement with available experimental data. This is significantly different from the case of 3He on clean graphite, in which both theory and experiment agree on the existence of a gas-liquid transition at low densities. Upon an increase in 3He density, we predict a first-order phase transition between a dense liquid and a registered 7/12 phase, the 4/7 phase being found metastable in our calculations. At larger second-layer densities, a final transition is produced to an incommensurate triangular phase.

  18. 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.

  19. 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.

  20. Neutron scattering from solid 3He

    NASA Astrophysics Data System (ADS)

    Schanen, R.; Sherline, T. E.; Toader, A. M.; Boyko, V.; Mat'as, S.; Meschke, M.; Schöttl, S.; Adams, E. D.; Cowan, B.; Godfrin, H.; Goff, J. P.; Roger, M.; Saunders, J.; Siemensmeyer, K.; Takano, Y.

    2003-05-01

    Multiple spin exchange leads, according to present understanding, to a variety of magnetically ordered states in solid 3He, depending on pressure and applied magnetic field. We report the status of experiments to directly determine these structures by neutron scattering. The large neutron absorption cross section, and associated sample heating, impose severe experimental demands on the design of the sample cell. We report on our proposed solution, including details of the sintered heat exchanger necessary to cool the sample, as well as the PrNi 5 nuclear demagnetization stage. The use of NMR in parallel experiments to characterise growth of the solid sample within the sinter is also discussed.

  1. 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.

  2. 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.

  3. 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.

  4. The SLAC E-154 {sup 3}He polarimeter

    SciTech Connect

    Romalis, M. V.; Bogorad, P. L.; Cates, G. D.; Kumar, K. S.; Chupp, T. E.; Coulter, K. P.; Smith, T. B.; Welsh, R.; Hughes, E. W.; Johnson, J. R.; Thompson, A. K.

    1998-01-20

    We describe the NMR and Rb Zeeman frequency shift polarimeters used for determining the {sup 3}He polarization in a recent precision measurement of the neutron spin structure function g{sub 1} at SLAC (E-154). We performed a detailed study of the systematic errors associated with the calibration of the NMR polarimeter. A new technique was used for determining the {sup 3}He polarization from the frequency shift of the Rb Zeeman resonance.

  5. 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.

  6. 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.

  7. 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.

  8. Effect of hyperfine-induced spin mixing on the defect-enabled spin blockade and spin filtering in GaNAs

    NASA Astrophysics Data System (ADS)

    Puttisong, Y.; Wang, X. J.; Buyanova, I. A.; Chen, W. M.

    2013-03-01

    The effect of hyperfine interaction (HFI) on the recently discovered room-temperature defect-enabled spin-filtering effect in GaNAs alloys is investigated both experimentally and theoretically based on a spin Hamiltonian analysis. We provide direct experimental evidence that the HFI between the electron and nuclear spin of the central Ga atom of the spin-filtering defect, namely, the Gai interstitials, causes strong mixing of the electron spin states of the defect, thereby degrading the efficiency of the spin-filtering effect. We also show that the HFI-induced spin mixing can be suppressed by an application of a longitudinal magnetic field such that the electronic Zeeman interaction overcomes the HFI, leading to well-defined electron spin states beneficial to the spin-filtering effect. The results provide a guideline for further optimization of the defect-engineered spin-filtering effect.

  9. 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.

  10. Notch filtering the nuclear environment of a spin qubit

    NASA Astrophysics Data System (ADS)

    Malinowski, Filip K.; Martins, Frederico; Nissen, Peter D.; Barnes, Edwin; Cywiński, Łukasz; Rudner, Mark S.; Fallahi, Saeed; Gardner, Geoffrey C.; Manfra, Michael J.; Marcus, Charles M.; Kuemmeth, Ferdinand

    2017-01-01

    Electron spins in gate-defined quantum dots provide a promising platform for quantum computation. In particular, spin-based quantum computing in gallium arsenide takes advantage of the high quality of semiconducting materials, reliability in fabricating arrays of quantum dots and accurate qubit operations. However, the effective magnetic noise arising from the hyperfine interaction with uncontrolled nuclear spins in the host lattice constitutes a major source of decoherence. Low-frequency nuclear noise, responsible for fast (10 ns) inhomogeneous dephasing, can be removed by echo techniques. High-frequency nuclear noise, recently studied via echo revivals, occurs in narrow-frequency bands related to differences in Larmor precession of the three isotopes 69Ga, 71Ga and 75As (refs 15,16,17). Here, we show that both low- and high-frequency nuclear noise can be filtered by appropriate dynamical decoupling sequences, resulting in a substantial enhancement of spin qubit coherence times. Using nuclear notch filtering, we demonstrate a spin coherence time (T2) of 0.87 ms, five orders of magnitude longer than typical exchange gate times, and exceeding the longest coherence times reported to date in Si/SiGe gate-defined quantum dots.

  11. Notch filtering the nuclear environment of a spin qubit.

    PubMed

    Malinowski, Filip K; Martins, Frederico; Nissen, Peter D; Barnes, Edwin; Cywiński, Łukasz; Rudner, Mark S; Fallahi, Saeed; Gardner, Geoffrey C; Manfra, Michael J; Marcus, Charles M; Kuemmeth, Ferdinand

    2017-01-01

    Electron spins in gate-defined quantum dots provide a promising platform for quantum computation. In particular, spin-based quantum computing in gallium arsenide takes advantage of the high quality of semiconducting materials, reliability in fabricating arrays of quantum dots and accurate qubit operations. However, the effective magnetic noise arising from the hyperfine interaction with uncontrolled nuclear spins in the host lattice constitutes a major source of decoherence. Low-frequency nuclear noise, responsible for fast (10 ns) inhomogeneous dephasing, can be removed by echo techniques. High-frequency nuclear noise, recently studied via echo revivals, occurs in narrow-frequency bands related to differences in Larmor precession of the three isotopes (69)Ga, (71)Ga and (75)As (refs 15,16,17). Here, we show that both low- and high-frequency nuclear noise can be filtered by appropriate dynamical decoupling sequences, resulting in a substantial enhancement of spin qubit coherence times. Using nuclear notch filtering, we demonstrate a spin coherence time (T2) of 0.87 ms, five orders of magnitude longer than typical exchange gate times, and exceeding the longest coherence times reported to date in Si/SiGe gate-defined quantum dots.

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

    PubMed

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

    2015-06-09

    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.

  13. 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

  14. Polarized 3He Neutron Spin Filters

    SciTech Connect

    Sno, William Michael

    2016-01-12

    The goal of this grant to Indiana University and subcontractors at Hamilton College and Wisconsin and the associated Interagency Agreement with NIST was to extend the technique of polarized neutron scattering by the development and application of polarized 3He-based neutron spin filters. This effort was blessed with long-term support from the DOE Office of Science, which started in 2003 and continued until the end of a final no-cost extension of the last 3-year period of support in 2013. The steady support from the DOE Office of Science for this long-term development project was essential to its eventual success. Further 3He neutron spin filter development is now sited at NIST and ORNL.

  15. Quantitative spin polarization analysis in photoelectron emission microscopy with an imaging spin filter.

    PubMed

    Tusche, Christian; Ellguth, Martin; Krasyuk, Alexander; Winkelmann, Aimo; Kutnyakhov, Dmytro; Lushchyk, Pavel; Medjanik, Katerina; Schönhense, Gerd; Kirschner, Jürgen

    2013-07-01

    Using a photoelectron emission microscope (PEEM), we demonstrate spin-resolved electron spectroscopic imaging of ultrathin magnetic Co films grown on Cu(100). The spin-filter, based on the spin-dependent reflection of low energy electrons from a W(100) crystal, is attached to an aberration corrected electrostatic energy analyzer coupled to an electrostatic PEEM column. We present a method for the quantitative measurement of the electron spin polarization at 4 × 10³ points of the PEEM image, simultaneously. This approach uses the subsequent acquisition of two images with different scattering energies of the electrons at the W(100) target to directly derive the spin polarization without the need of magnetization reversal of the sample.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

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

    PubMed

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

    2015-06-22

    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.

  2. 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.

  3. Optical detection of spin-filter effect for electron spin polarimetry

    SciTech Connect

    Li, X.; Majee, S.; Lampel, G.; Lassailly, Y.; Paget, D.; Peretti, J.; Tereshchenko, O. E.

    2014-08-04

    We have monitored the cathodoluminescence (CL) emitted upon injection of free electrons into a hybrid structure consisting of a thin magnetic Fe layer deposited on a p-GaAs substrate, in which InGaAs quantum wells are embedded. Electrons transmitted through the unbiased metal/semiconductor junction recombine radiatively in the quantum wells. Because of the electron spin-filtering across the Fe/GaAs structure, the CL intensity, collected from the backside, is found to depend on the relative orientation between the injected electronic spin polarization and the Fe layer magnetization. The spin asymmetry of the CL intensity in such junction provides a compact optical method for measuring spin polarization of free electrons beams or of hot electrons in solid-state devices.

  4. 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.

  5. 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.

  6. Elastic Compton Scattering from 3He

    NASA Astrophysics Data System (ADS)

    Margaryan, Arman; Griesshammer, Harald W.; Phillips, Daniel R.; Strandberg, Bruno; McGovern, Judith A.; Shukla, Deepshikha

    2017-01-01

    We study elastic Compton scattering on 3He using chiral effective field theory (χEFT) at photon energies from 60 MeV to approximately 120 MeV. Experiments to measure this process have been proposed for both MAMI at Mainz and the HI γS facility at TUNL. I will present the revised results of a full calculation at third order in the expansion (O (Q3)). The amplitude involves a sum of both one- and two-nucleon Compton-scattering mechanisms. We have recently computed the fourth-order two-nucleon diagrams. The numerical impact they have on the cross-section results will be discussed. I will also present results in which amplitudes used so far are augmented by the leading effects from Δ (1232) degrees of freedom, a step which has already been performed for the proton and deuteron processes. Both cross sections and doubly-polarized asymmetries will be presented, and the sensitivity of these observables to the values of neutron scalar and spin polarizabilities will be assessed. This material is based upon work supported in part by DOE and George Washington University.

  7. 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.

  8. Recent advances of polarized {sup 3}He target at Jefferson Lab

    SciTech Connect

    Qiang Yi

    2011-10-24

    Polarized {sup 3}He targets have been widely used in nuclear and particle physics experiments to study neutron structure in the spin degree of freedom, as most of the {sup 3}He spin is carried by the unpaired neutron. The Spin-Exchange Optical Pumping (SEOP) process is used in Jefferson Lab Hall A to polarize its {sup 3}He target. In recent years, both the performance and corresponding polarimetry of such a target have been greatly improved. Several experiments recently carried out in Hall A have achieved record high figure of merit using this target.

  9. Incorporating metal into polarized 3He target cells

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    An upcoming measurement at Jefferson Laboratory (JLab) of the electric form factor of the neutron will utilize a polarized 3He target at high luminosity. While polarized 3He targets at JLab have previously been made entirely of glass, we describe progress toward incorporating metal windows for the electron beam. Under the conditions of our targets, very few studies have been done on the spin-relaxation of nuclear-polarized 3He on metal surfaces. We have found good performance by using Oxygen Free High Conductivity (OFHC) copper substrates electroplated with gold. The glass-to-metal transitions within our test cells were based on Housekeeper seals. We have further established that Uranium glass (Canary glass) has excellent spin-relaxation properties, and can serve as a transition glass from Pyrex to Aluminosilicate glass (GE180). Another finding was that spin-relaxation properties were sensitive to the manner in which cells were annealed, an important issue because of constraints when annealing cells containing both metal and glass.

  10. 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.

  11. 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.

  12. 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.

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

    SciTech Connect

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

    2016-02-07

    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.

  14. 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.

  15. Limiting factor of defect-engineered spin-filtering effect at room temperature

    NASA Astrophysics Data System (ADS)

    Puttisong, Y.; Buyanova, I. A.; Chen, W. M.

    2014-05-01

    We identify hyperfine-induced electron and nuclear spin cross-relaxation as the dominant physical mechanism for the longitudinal electron spin relaxation time 1 of the spin-filtering Gai2+ defects in GaNAs alloys. This conclusion is based on our experimental findings that T1 is insensitive to temperature over 4-300 K, and its exact value is directly correlated with the hyperfine coupling strength of the defects that varies between different configurations of the Gai2+ defects present in the alloys. These results thus provide a guideline for further improvements of the spin-filtering efficiency by optimizing growth and processing conditions to preferably incorporate the Gai2+ defects with a weak hyperfine interaction and by searching for new spin-filtering defects with zero nuclear spin.

  16. Application of Sol-Gel Technology to High Pressure Polarized 3HE Nuclear Targets

    NASA Astrophysics Data System (ADS)

    Tobias, W. A.; Cates, G. D.; Chaput, J.; Deur, A.; Rohrbaugh, S.; Singh, J.

    2003-01-01

    High-purity sol-gel solutions have been developed to coat the interior surface of glass vessels used for polarizing 3He by spin-exchange optical pumping. Such cells have been shown to exhibit 3He longitudinal lifetimes T1 in excess of 350 hours1. The sol-gel technique was designed to minimize spin-relaxation due to wall collisions so that only dipole-dipole interactions between colliding 3He atoms dominate in the relaxation process. Until now, sol-gel technology had not been applied to high pressure 3He gas targets used in nuclear scattering experiments. A description of the sol-gel technique and recent developments on its integration into the production of 3He targets will be presented.

  17. 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

  18. Symmetry protected topological superfluid (3)He-B.

    PubMed

    Mizushima, Takeshi; Tsutsumi, Yasumasa; Sato, Masatoshi; Machida, Kazushige

    2015-03-25

    Owing to the richness of symmetry and well-established knowledge of bulk superfluidity, the superfluid (3)He has offered a prototypical system to study intertwining of topology and symmetry. This article reviews recent progress in understanding the topological superfluidity of (3)He in a multifaceted manner, including symmetry considerations, the Jackiw-Rebbi's index theorem, and the quasiclassical theory. Special focus is placed on the symmetry protected topological superfuidity of the (3)He-B confined in a slab geometry. The (3)He-B under a magnetic field is separated to two different sub-phases: the symmetry protected topological phase and non-topological phase. The former phase is characterized by the existence of symmetry protected Majorana fermions. The topological phase transition between them is triggered by the spontaneous breaking of a hidden discrete symmetry. The critical field is quantitatively determined from the microscopic calculation that takes account of magnetic dipole interaction of the (3)He nucleus. It is also demonstrated that odd-frequency even-parity Cooper pair amplitudes are emergent in low-lying quasiparticles. The key ingredients, symmetry protected Majorana fermions and odd-frequency pairing, bring an important consequence that the coupling of the surface states to an applied field is prohibited by the hidden discrete symmetry, while the topological phase transition with the spontaneous symmetry breaking is accompanied by anomalous enhancement and anisotropic quantum criticality of surface spin susceptibility. We also illustrate common topological features between topological crystalline superconductors and symmetry protected topological superfluids, taking UPt3 and Rashba superconductors as examples.

  19. Helix-Dependent Spin Filtering through the DNA Duplex.

    PubMed

    Zwang, Theodore J; Hürlimann, Sylvia; Hill, Michael G; Barton, Jacqueline K

    2016-12-07

    Recent work suggests that electrons can travel through DNA and other chiral molecules in a spin-selective manner, but little is known about the origin of this spin selectivity. Here we describe experiments on magnetized DNA-modified electrodes to explore spin-selective electron transport through hydrated duplex DNA. Our results show that the two spins migrate through duplex DNA with a different yield and that spin selectivity requires charge transport through the DNA duplex. Significantly, shifting the same duplex DNA between right-handed B- and left-handed Z-forms leads to a diode-like switch in spin selectivity; which spin moves more efficiently through the duplex depends upon the DNA helicity. With DNA, the supramolecular organization of chiral moieties, rather than the chirality of the individual monomers, determines the selectivity in spin, and thus a conformational change can switch the spin selectivity.

  20. 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.

  1. Superfluid 3He in ``nematically ordered'' aerogel

    NASA Astrophysics Data System (ADS)

    Dmitriev, Vladimir

    2014-03-01

    Liquid 3He immersed in aerogel allows investigation of the influence of impurities on unconventional superfluidity. In most of such experiments silica aerogels are used. These aerogels consist of thin strands which form a ``wisp.'' Although it is established that superfluid phases of 3He in silica aerogels (A-like and B-like) have the same order parameters as A and B phases of bulk 3He, many new phenomena were observed. In particular, it was found that global anisotropy of aerogel (e.g. caused by squeezing or stretching) can orient the order parameter. Depending on prehistory and on the type of the anisotropy the A-like phase may be homogeneous or in a state with random orbital part of the order parameter. Theory predicts that a large stretching anisotropy may even influence the order parameter structure: polar phase (or A phase with polar distortion), which are not realized in bulk 3He, may become more favorable than pure A phase. Large stretching anisotropy is hardly achievable in silica aerogel. Therefore in experiments described in the talk we used a new type of aerogel, consisting of Al2O3 . H2O strands which are parallel to each other, i.e. this aerogel may be considered as infinitely stretched. We found that the superfluid phase diagram of 3He in such ``nematically ordered'' aerogel is different from the case of 3He in silica aerogel and that both observed A and B phases have large polar distortion. This distortion is larger at low pressures and grows on warming. There are indications that a pure polar phase appears near the superfluid transition temperature. Recent results will be also presented.

  2. Synthesis of low-moment CrVTiAl: A potential room temperature spin filter

    NASA Astrophysics Data System (ADS)

    Stephen, G. M.; McDonald, I.; Lejeune, B.; Lewis, L. H.; Heiman, D.

    2016-12-01

    The efficient production of spin-polarized currents at room temperature is fundamental to the advancement of spintronics. Spin-filter materials—semiconductors with unequal band gaps for each spin channel—can generate spin-polarized current without the need for spin-polarized contacts. In addition, a spin-filter material with zero magnetic moment would have the advantage of not producing strong fringing fields that would interfere with neighboring electronic components and limit the volume density of devices. The quaternary Heusler compound CrVTiAl has been predicted to be a zero-moment spin-filter material with a Curie temperature in excess of 1000 K. In this work, CrVTiAl has been synthesized with a lattice constant of a = 6.15 Å. Magnetization measurements reveal an exceptionally low moment of μ = 2.3 × 10-3 μB/f.u. at a field of μ0H = 2 T that is independent of temperature between T = 10 K and 400 K, consistent with the predicted zero-moment ferrimagnetism. Transport measurements reveal a combination of metallic and semiconducting components to the resistivity. Combining a zero-moment spin-filter material with nonmagnetic electrodes would lead to an essentially nonmagnetic spin injector. These results suggest that CrVTiAl is a promising candidate for further research in the field of spintronics.

  3. The multiuniverse transition in superfluid 3He

    NASA Astrophysics Data System (ADS)

    Bunkov, Yury

    2013-10-01

    The symmetry-breaking phase transitions of the universe and of superfluid 3He may lead to the formation of different states with different order parameters. In both cases the energy potential below the transition temperature has a complicated multidimensional profile with many local minima and saddle points, which correspond to different states. Consequently, not only topological defects, but also islands of different metastable states can be created. Using 3He we can analyse the properties and experimental consequences of such transitions and, in particular, the first-order phase transition between the two low symmetry states.

  4. The multiuniverse transition in superfluid 3He.

    PubMed

    Bunkov, Yury

    2013-10-09

    The symmetry-breaking phase transitions of the universe and of superfluid (3)He may lead to the formation of different states with different order parameters. In both cases the energy potential below the transition temperature has a complicated multidimensional profile with many local minima and saddle points, which correspond to different states. Consequently, not only topological defects, but also islands of different metastable states can be created. Using (3)He we can analyse the properties and experimental consequences of such transitions and, in particular, the first-order phase transition between the two low symmetry states.

  5. 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.

  6. 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.

  7. 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.

  8. Quasi-elastic electron scattering from polarized 3He

    SciTech Connect

    H. J. Bulten; Ricardo Alarcon; Th. Bauer; D. Boersma; T. Botto; J. F. J. van den Brand; L. van Buuren; Rolf Ent; M. Ferro-Luzzi; D. Geurts; M. Harvey; Peter Heimberg; D. Highinbotham; Kees de Jager; Blaine Norum; I. Passchier; H. R. Poolman; M. van den Putte; E. Six; J. Steijger; D. Szczerba; H. de Vries

    1997-08-01

    Quasi-elastic electron scattering may provide precise information on the S and the D-wave parts of the {sup 3}He ground-state wave function, the neutron form factors, and the role of spin-dependent reaction mechanism effects. An experiment is being performed at the AmPS storage ring at NIKHEF (Amsterdam, the Netherlands), where polarized electrons (up to 900 MeV) are used in combination with large acceptance electron and hadron detectors. Preliminary results from data at four-momentum transfer squared Q{sup 2} = 0.15 GeV{sup 2} are presented.

  9. Spin Filtering in a Rashba Electron Waveguide Induced by Edge Disorder

    NASA Astrophysics Data System (ADS)

    Xiao, Xian-Bo; Li, Fei; Liu, Nian-Hua

    2012-08-01

    We theoretically study the spin-dependent electron transport in a Rashba electron waveguide with rough edges, attached to ideal leads without spin-orbit interaction. The influence of the edge disorder on the charge and spin conductances is clarified by using the spin-resolved lattice Green function method. It is found that a spin-polarized current can be generated in the output lead and its spin polarization can be manipulated by varying the waveguide length. The underlying physics is attributed to the broken longitudinal symmetry and the spin-dependent quantum interference induced by the rough boundaries. Our results may provide a new method to design a spin filter without using magnetic materials or applying a magnetic field.

  10. Single-Shot Ternary Readout of Two-Electron Spin States in a Quantum Dot Using Spin Filtering by Quantum Hall Edge States.

    PubMed

    Kiyama, H; Nakajima, T; Teraoka, S; Oiwa, A; Tarucha, S

    2016-12-02

    We report on the single-shot readout of three two-electron spin states-a singlet and two triplet substates-whose z components of spin angular momentum are 0 and +1, in a gate-defined GaAs single quantum dot. The three spin states are distinguished by detecting spin-dependent tunnel rates that arise from two mechanisms: spin filtering by spin-resolved edge states and spin-orbital correlation with orbital-dependent tunneling. The three states form one ground state and two excited states, and we observe the spin relaxation dynamics among the three spin states.

  11. Chiral Phases of Superfluid 3He in an Anisotropic Medium

    NASA Astrophysics Data System (ADS)

    Sauls, James

    2013-03-01

    I report theoretical results for the phases of superfluid 3He infused into homogeneous uniaxial aerogel. Ginzburg-Landau (GL) theory for a class of equal-spin-pairing (ESP) states in a medium with uniaxial anisotropy is developed and used to analyze recent experiments on uniaxially strained aerogels. For 3He in an axially ``stretched'' aerogel GL theory predicts a transition from normal liquid into a chiral ABM phase in which the chirality axis is aligned along the strain axis. This state is protected from random fluctuations in the anisotropy direction, has a positive NMR shift, a sharp NMR resonance line and is in quantitative agreement with NMR in the high-temperature ESP-1 phase of superfluid 3He in axially stretched aerogel. A second transition into a bi-axial phase is predicted to onset at a slightly lower temperature. This phase is an ESP state, breaks time-reversal symmetry, and is defined by an order parameter that spontaneously breaks axial rotation symmetry. The bi-axial phase has a continuous degeneracy associated with broken axial symmetry. Theoretical predictions for the NMR frequency shifts provide an identification of the ESP-2 phase as the bi-axial state, partially disordered by random anisotropy (Larkin-Imry-Ma effect). Supported by National Science Foundation Grant DMR-1106315.

  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. Room-Temperature Spin Filtering in Metallic Ferromagnet-Multilayer Graphene-Ferromagnet Junctions.

    PubMed

    Cobas, Enrique D; van 't Erve, Olaf M J; Cheng, Shu-Fan; Culbertson, James C; Jernigan, Glenn G; Bussman, Konrad; Jonker, Berend T

    2016-11-22

    We report room-temperature negative magnetoresistance in ferromagnet-graphene-ferromagnet (FM|Gr|FM) junctions with minority spin polarization exceeding 80%, consistent with predictions of strong minority spin filtering. We fabricated arrays of such junctions via chemical vapor deposition of multilayer graphene on lattice-matched single-crystal NiFe(111) films and standard photolithographic patterning and etching techniques. The junctions exhibit metallic transport behavior, low resistance, and the negative magnetoresistance characteristic of a minority spin filter interface throughout the temperature range 10 to 300 K. We develop a device model to incorporate the predicted spin filtering by explicitly treating a metallic minority spin channel with spin current conversion and a tunnel barrier majority spin channel and extract spin polarization of at least 80% in the graphene layer in our structures. The junctions also show antiferromagnetic coupling, consistent with several recent predictions. The methods and findings are relevant to fast-readout low-power magnetic random access memory technology, spin logic devices, and low-power magnetic field sensors.

  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. 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.

  17. Spin filtering effect generated by the inter-subband spin-orbit coupling in the bilayer nanowire with the quantum point contact.

    PubMed

    Wójcik, Paweł; Adamowski, Janusz

    2017-03-30

    The spin filtering effect in the bilayer nanowire with quantum point contact is investigated theoretically. We demonstrate the new mechanism of the spin filtering based on the lateral inter-subband spin-orbit coupling, which for the bilayer nanowires has been reported to be strong. The proposed spin filtering effect is explained as the joint effect of the Landau-Zener intersubband transitions caused by the hybridization of states with opposite spin (due to the lateral Rashba SO interaction) and the confinement of carriers in the quantum point contact region.

  18. Spin filtering effect generated by the inter-subband spin-orbit coupling in the bilayer nanowire with the quantum point contact

    PubMed Central

    Wójcik, Paweł; Adamowski, Janusz

    2017-01-01

    The spin filtering effect in the bilayer nanowire with quantum point contact is investigated theoretically. We demonstrate the new mechanism of the spin filtering based on the lateral inter-subband spin-orbit coupling, which for the bilayer nanowires has been reported to be strong. The proposed spin filtering effect is explained as the joint effect of the Landau-Zener intersubband transitions caused by the hybridization of states with opposite spin (due to the lateral Rashba SO interaction) and the confinement of carriers in the quantum point contact region. PMID:28358141

  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. 3He: cosmological and atomic physics experiments.

    PubMed

    Bunkov, Yuriy M

    2008-08-28

    Because the superfluid 3He order parameter exhibits many similarities with that of our Universe, the superfluid condensate may be considered as a quantum vacuum that carries various types of quasiparticles and topological defects. The condensate thus provides a test system for the experimental investigation of many general physics problems in cosmology, atomic or nuclear physics that are otherwise difficult or even impossible to investigate experimentally.

  1. 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.

  2. Spin filtering in a Rashba-Dresselhaus-Aharonov-Bohm double-dot interferometer

    NASA Astrophysics Data System (ADS)

    Matityahu, Shlomi; Aharony, Amnon; Entin-Wohlman, Ora; Tarucha, Seigo

    2013-12-01

    We study the spin-dependent transport of spin-1/2 electrons through an interferometer made of two elongated quantum dots or quantum nanowires, which are subject to both an Aharonov-Bohm flux and (Rashba and Dresselhaus) spin-orbit interactions. Similar to the diamond interferometer proposed in our previous papers (Aharony et al 2011 Phys. Rev. B 84 035323; Matityahu et al 2013 Phys. Rev. B 87 205438), we show that the double-dot interferometer can serve as a perfect spin filter due to a spin interference effect. By appropriately tuning the external electric and magnetic fields which determine the Aharonov-Casher and Aharonov-Bohm phases, and with some relations between the various hopping amplitudes and site energies, the interferometer blocks electrons with a specific spin polarization, independent of their energy. The blocked polarization and the polarization of the outgoing electrons is controlled solely by the external electric and magnetic fields and do not depend on the energy of the electrons. Furthermore, the spin filtering conditions become simpler in the linear-response regime, in which the electrons have a fixed energy. Unlike the diamond interferometer, spin filtering in the double-dot interferometer does not require high symmetry between the hopping amplitudes and site energies of the two branches of the interferometer and thus may be more appealing from an experimental point of view.

  3. 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.

  4. Sol-gel coatings for high pressure polarized ^3He nuclear targets

    NASA Astrophysics Data System (ADS)

    Deur, Alexandre; Cates, Gordon D.; Chaput, Julien; Singh, Jaideep; Tobias, William A.

    2001-11-01

    Sol-gel coated glass cells have been shown to exhibit longitudinal lifetimes T1 in excess of 350 hours for ^3He that is polarized by spin-exchange optical pumping.( Ming F. Hsu shape et al, Appl. Phys. Lett.) series 77 (2000) 2069. The sol-gel technique was designed to minimize spin-relaxation due to wall collisions so that only dipole-dipole interactions between colliding ^3He atoms dominate in the relaxation process. Until now, sol-gel technology has not been applied to high pressure ^3He gas targets used in nuclear scattering experiments. Latest developments on incorporating the sol-gel technique in the production of these ^3He targets will be presented.

  5. Spin filtering in all-electrical three-terminal interferometers

    NASA Astrophysics Data System (ADS)

    Matityahu, S.; Aharony, A.; Entin-Wohlman, O.; Balseiro, C. A.

    2017-02-01

    Unlike the two-terminal device, in which the time-reversal invariant spin-orbit interaction alone cannot polarize the spins, such a polarization can be generated when electrons from one source reservoir flow into two (or more) separate drain reservoirs. We present analytical solutions for two examples. First, we demonstrate that the electrons transmitted through a "diamond" interferometer into two drains can be simultaneously fully spin polarized along different tunable directions, even when the two arms of the interferometer are not identical. Second, we show that a single helical molecule attached to more than one drain can induce a significant spin polarization in electrons passing through it. The average polarization remains nonzero even when the electrons outgoing into separate leads are eventually mixed incoherently into one absorbing reservoir. This may explain recent experiments on spin selectivity of certain helical-chiral molecules.

  6. 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.

  7. 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.

  8. Four-state non-volatile memory in a multiferroic spin filter tunnel junction

    NASA Astrophysics Data System (ADS)

    Ruan, Jieji; Li, Chen; Yuan, Zhoushen; Wang, Peng; Li, Aidong; Wu, Di

    2016-12-01

    We report a spin filter type multiferroic tunnel junction with a ferromagnetic/ferroelectric bilayer barrier. Memory functions of a spin filter magnetic tunnel junction and a ferroelectric tunnel junction are combined in this single device, producing four non-volatile resistive states that can be read out in a non-destructive manner. This concept is demonstrated in a LaNiO3/Pr0.8Ca0.2MnO3/BaTiO3/La0.7Sr0.3MnO3 all-oxide tunnel junction. The ferromagnetic insulator Pr0.8Ca0.2MnO3 serves as the spin filter and the ferromagnetic metal La0.7Sr0.3MnO3 is the spin analyzer. The ferroelectric polarization reversal in the BaTiO3 barrier switches the tunneling barrier height to produce a tunneling electroresistance. The ferroelectric switching also modulates the spin polarization and the spin filtering efficiency in Pr0.8Ca0.2MnO3.

  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. 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

  11. Intense polarized /sup 3/He ion source

    SciTech Connect

    Slobodrian, R.J.; Bertrand, R.; Grioux, J.; Labrie, R.; Lapainte, R.; Meunier, J.F.; Pigeon, G.; Pouliot, L.; Rioux, C.; Roy, R.

    1985-10-01

    This source is based on the atomic polarization of the 2/sup 3/S/sub 1/ metastable state of the neutral atom. A version suitable for operation on the high voltage terminal of a CN Van de Graaff has been constructed, bench tested and installed in the terminal of a 7.5 MV machine. The polarization of the atomic beam is higher than 90%. It is now fully operational and a current of /sup 3/He/sup +/ of 300 nA has been measured after acceleration.

  12. Low temperature nano-spin filtering using a diluted magnetic semiconductor core-shell quantum dot

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Saikat; Sen, Pratima; Andrews, Joshep Thomas; Sen, Pranay Kumar

    2014-07-01

    The spin polarized electron transport properties and spin polarized tunneling current have been investigated analytically in a diluted magnetic semiconductor core-shell quantum dot in the presence of applied electric and magnetic fields. Assuming the electron wave function to satisfy WKB approximation, the electron energy eigenvalues have been calculated. The spin polarized tunneling current and the spin dependent tunneling coefficient are obtained by taking into account the exchange interaction and Zeeman splitting. Numerical estimates made for a specific diluted magnetic semiconductor, viz., Zn1-xMnxSe/ZnS core-shell quantum dot establishes the possibility of a nano-spin filter for a particular biasing voltage and applied magnetic field. Influence of applied voltage on spin polarized electron transport has been investigated in a CSQD.

  13. Neutron Diffuse Reflectometry of Magnetic Thin Films with a 3He Analyzer

    NASA Astrophysics Data System (ADS)

    Chen, Wangchun; O'Donovan, Kevin; Borchers, Julie

    2005-03-01

    Polarized neutron reflectometry (PNR) is a powerful probe that characterizes the magnetization depth profile and magnetic domains in magnetic thin films. Although the conventionally used supermirrors are well-matched for specular PNR, they have limited angular acceptance and hence are impractical for complete characterization of the magnetic off-specular scattering where polarization analysis for diffusely reflected neutrons is required. Polarized ^3He gas, produced by optical pumping, can be used to polarize or analyze neutron beams because of the strong spin dependence of the neutron absorption cross section for ^3He. Here we report efficient polarization analysis of diffusely reflected neutrons in a reflectometry geometry using a polarized ^3He analyzer in conjunction with a position-sensitive detector (PSD). We obtained spin-resolved two-dimensional Qx-Qz reciprocal space maps for a patterned array of Co antidots in both the saturated and the demagnetized states. The preliminary results for a patterned amorphous bilayer, Gd40Fe60/ Tb55Fe45, measured with a ^3He analyzer and a PSD will also be discussed. Using the spin exchange optical pumping method we have achieved record high ^3He polarizations of 76% on the neutron beam line where we measured an initial analyzing efficiency of 0.97 and a neutron transmission for the desired spin state of 0.45.

  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. 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.

  16. 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.

  17. 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.

  18. 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}.

  19. {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.

  20. 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.

  1. 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.

  2. 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.

  3. Perfect spin filtering and large spin thermoelectric effects in organic transition-metal molecular junctions.

    PubMed

    Yang, X F; Liu, Y S; Zhang, X; Zhou, L P; Wang, X F; Chi, F; Feng, J F

    2014-06-21

    We present ab initio studies of spin-polarized transport properties and thermospin effects in cyclopentadienyl-iron molecular junctions. It is found that the spin-up transmission coefficient at the Fermi level shows an odd-even oscillating behaviour, while the spin-down transmission coefficient has an exponential decay with the molecule length. The spin polarization at the Fermi level rapidly tends toward a saturation value close to 100% with the molecule length. This is ascribed to the existence of different orbital states for different spin components at the Fermi level. In addition, we find that the spin-up Seebeck coefficient oscillates between positive and negative values, while the spin-down Seebeck coefficient always has a positive value and monotonically increases with the molecule length. Therefore in some cases, the spin Seebeck coefficient is even larger than the corresponding charge Seebeck effect. Finally, we also provide a possibility of utilizing cyclopentadienyl-iron molecular junctions to achieve the pure spin current without an accompanying charge current at about room temperature.

  4. Low temperature properties of spin filter NbN/GdN/NbN Josephson junctions

    NASA Astrophysics Data System (ADS)

    Massarotti, D.; Caruso, R.; Pal, A.; Rotoli, G.; Longobardi, L.; Pepe, G. P.; Blamire, M. G.; Tafuri, F.

    2017-02-01

    A ferromagnetic Josephson junction (JJ) represents a special class of hybrid system where different ordered phases meet and generate novel physics. In this work we report on the transport measurements of underdamped ferromagnetic NbN/GdN/NbN JJs at low temperatures. In these junctions the ferromagnetic insulator gadolinium nitride barrier generates spin-filtering properties and a dominant second harmonic component in the current-phase relation. These features make spin filter junctions quite interesting also in terms of fundamental studies on phase dynamics and dissipation. We discuss the fingerprints of spin filter JJs, through complementary transport measurements, and their implications on the phase dynamics, through standard measurements of switching current distributions. NbN/GdN/NbN JJs, where spin filter properties can be controllably tuned along with the critical current density (Jc), turn to be a very relevant term of reference to understand phase dynamics and dissipation in an enlarged class of JJs, not necessarily falling in the standard tunnel limit characterized by low Jc values.

  5. 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.

  6. 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.

  7. Perfect spin filtering, rectifying and negative differential resistance effects in armchair graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Zhang, Dan; Long, Mengqiu; Zhang, Xiaojiao; Cui, Liling; Li, Xinmei; Xu, Hui

    2017-03-01

    Using the non-equilibrium Green's function method combined with the spin-polarized density functional theory, we calculate the electronic and transport properties of the armchair graphene nanoribbons with a special edge hydrogenation (S-AGNRs). The results show S-AGNRs are ferromagnetic bipolar magnetic semiconductors with 2 μ B magnetic moment, and the B or N atom doping can make S-AGNRs convert to up-spin dominated or down-spin dominated half metal. Therefore, a 100% spin-filtering effect has been realized in the corresponding devices. Furthermore, the negative differential resistance phenomenon can also be found. The B and N atoms co-doping can construct a PN junction, and the rectification ratio is as high as 1010.

  8. sup 3 He- sup 3 He dating: A case for mixing of young and old groundwaters

    SciTech Connect

    Kamensky, I.L.; Tolstikhin, I.N. ); Tokarev, I.V. )

    1991-10-01

    {sup 3}He/{sup 4}He and {sup 20}Ne/{sup 4}He ratios were measured in shallow underground waters (opened by water-supplying wells) of the Large Vud-Javr intramountain artesian basin in the Khibiny alkaline massif, the Kola Peninsula. The ratios vary from 1.321 {times} 10{sup {minus}6} to 2.065 {times} 10{sup {minus}6} and from 1.412 to 2.941, respectively, and a well-defined correlation is observed between them. Both these ratios in aquifers are known to be time-dependent, the former increases with time due to accumulation of {sup 3}He, produced in waters by {sup 3}H {beta}-decay; the latter decreases due to migration of helium from water-bearing rocks into the waters. The correlation is interpreted as a result of the mixing of two different types of waters. The approximation line enables the authors to estimate the isotopic ratios for the endmembers participating in the mixing and the mean residence time ({tau}) of tritigenic helium-3 in the water: (1) {sup 3}He/{sup 4}He = 3.655 {times} 10{sup {minus}6}, {sup 20}Ne/{sup 4}He = 4.03, and taking into consideration {sup 3}H concentrations in the well waters, {sup 3}H = 31.1 TU (practically the same for all samples), {tau} = 15.8 {plus minus} 1.5 years for the young water; (2) {sup 3}He/{sup 4}He = 0.20 {times} 10{sup {minus}6}, {sup 20}Ne/{sup 4}He = 0.18 and T = 0.11 Ma for the old one, the contribution of the old water being less than 10%. In one well a considerable contribution of modern-day meteoric water, about 16%, is observed.

  9. Chiral phases of superfluid 3He in an anisotropic medium

    NASA Astrophysics Data System (ADS)

    Sauls, J. A.

    2013-12-01

    Recent advances in the fabrication and characterization of anisotropic silica aerogels with exceptional homogeneity provide new insight into the nature of unconventional pairing in disordered anisotropic media. I report theoretical analysis and predictions for the equilibrium phases of superfluid 3He infused into a low-density, homogeneous uniaxial aerogel. Ginzburg-Landau (GL) theory for a class of equal-spin-pairing (ESP) states in a medium with uniaxial anisotropy is developed and used to analyze recent experiments on uniaxially strained aerogels. For 3He in an axially “stretched” aerogel, GL theory predicts a transition from normal liquid into a chiral Anderson-Morel phase at Tc1 in which the chirality axis l̂ is aligned along the strain axis. This orbitally aligned state is protected from random fluctuations in the anisotropy direction, has a positive nuclear magnetic resonance (NMR) frequency shift, a sharp NMR resonance line, and is identified with the high-temperature ESP-1 phase of superfluid 3He in axially stretched aerogel. A second transition into a biaxial phase is predicted to onset at a slightly lower temperature Tc2

  10. Transport of polarized 3He for the nEDM experiment at the SNS

    NASA Astrophysics Data System (ADS)

    Rao, Thomas; Beck, Douglas; Koivuniemi, Jaakko; Silvera, Ike; Williamson, Steven; Yao, Weijun; nEDM Collaboration

    2016-09-01

    The neutron electric dipole moment (nEDM) experiment at the ORNL SNS aims to determine the neutron's electric dipole moment to an accuracy of 5.4 x 10-28 e cm by measuring the Lamor precession of neutrons using the spin dependent reaction n +3He =>p +3H +764KeV. In the experiment polarized 3He is injected into a free surface of 4He, and then brought to the measurement cell and removed once it depolarizes. The proposed transport method for the 3He, the heat flush mechanism, must be tested. In the heat flush mechanism a thermal gradient along a long pipe, generates phonons whose collisions with 3He, drives 3He transport to the cold end of the pipe. Tests of the heat flush mechanism by measuring the change in 3He concentration at the cold end of a long pipe, using a capacitive pressure sensor, are underway at Harvard University. Work supported in part by NSF Grants PHY-1440011 and PHY-1506416.

  11. 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.

  12. Comparative analysis of interferogram noise filtration using wavelet transform and spin filtering algorithms

    NASA Astrophysics Data System (ADS)

    Zielinski, B.; Patorski, K.

    2010-06-01

    The aim of this paper is to analyze 2D fringe pattern denoising performed by two chosen methods based on quasi-1D two-arm spin filter and 2D discrete wavelet transform (DWT) signal decomposition and thresholding. The ultimate aim of this comparison is to estimate which algorithm is better suited for high-accuracy measurements by phase shifting interferometry (PSI) with the phase step evaluation using the lattice site approach. The spin filtering method proposed by Yu et al. (1994) was designed to minimize possible fringe blur and distortion. The 2D DWT also presents such features due to a lossless nature of the signal wavelet decomposition. To compare both methods, a special 2D histogram introduced by Gutman and Weber (1998) is used to evaluate intensity errors introduced by each of the presented algorithms.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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%.

  19. Performance Limits of Pulse Tube Cryocoolers Using 3HE

    NASA Astrophysics Data System (ADS)

    Kittel, P.

    2008-03-01

    The enthalpy, entropy, and exergy flows resulting from the real gas effects of 3He in ideal pulse tube cryocoolers are described. The discussion follows a previous description of the real gas effects of 4He in ideal pulse tube cryocoolers and makes use of a recently developed model of the thermophysical properties of 3He. This model is used to describe how the thermodynamic flows are affected by real gas phenomena of 3He and compares these effects to similar effects for 4He. The analysis was done over the pressure range 0.3-2 MPa and temperatures down to 1 K. At 2 MPa there is almost no difference in the cooling power between 3He and 4He. At lower pressures, using 3He is advantageous. There is a 1-2 K reduction in the 3He cooling power vs. temperature curves compared to those for 4He in the 0.3-1 MPa range.

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

    DOE PAGES

    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

  1. 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...

  2. Magnetized liquid 3He at finite temperature: A variational calculation approach

    NASA Astrophysics Data System (ADS)

    Bordbar, Gholam Hossein; Mohammadi Sabet, Mohammad Taghi

    2016-08-01

    Using the spin-dependent (SD) and spin-independent (SI) correlation functions, we have investigated the properties of liquid 3He in the presence of magnetic field at finite temperature. Our calculations have been done using the variational method based on cluster expansion of the energy functional. Our results show that the low field magnetic susceptibility obeys Curie law at high temperatures. This behavior is in a good agreement with the experimental data as well as the molecular field theory results in which the spin dependency has been introduced in correlation function. Reduced susceptibility as a function of temperature as well as reduced temperature has been also investigated, and again we have seen that the spin-dependent correlation function leads to a good agreement with the experimental data. The Landau parameter, F0a, has been calculated, and for this parameter, a value about - 0.75 has been found in the case of spin-spin correlation. In the case of spin-independent correlation function, this value is about - 0.7. Therefore, inclusion of spin dependency in the correlation function leads to a more compatible value of F0a with experimental data. The magnetization and susceptibility of liquid 3He have also been investigated as a function of magnetic field. Our results show a downward curvature in magnetization of system with spin-dependent correlation for all densities and relevant temperatures. A metamagnetic behavior has been observed as a maximum in susceptibility versus magnetic field, when the spin-spin correlation has been considered. This maximum occurs at 45T ≤ B ≤ 100T for all densities and temperatures. This behavior has not been observed in the case of spin-independent correlation function.

  3. 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}.

  4. 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.

  5. /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.

  6. 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

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

    SciTech Connect

    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 and 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.

  8. 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.

  9. 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.

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

    PubMed Central

    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

  11. 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

    2016-08-31

    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.

  12. 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.

  13. 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.

  14. Superfluid 3-He: The Early Days as Seen by a Theorist

    NASA Astrophysics Data System (ADS)

    Leggett, Anthony

    2004-03-01

    After some background, I give some very personal reminiscences of the twelve-month period between July 1972 and July 1973, in which we came to a theoretical understanding of the puzzling experimental data on what we now know as superfluid 3-He. I particularly emphasize the concept of "spontaneously broken spin-orbit symmetry", which turned out to be important in understanding the NMR data.

  15. 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).

  16. 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.

  17. 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.

  18. Comparative analysis of the interferogram noise filtration using wavelet transform and spin filtering algorithms

    NASA Astrophysics Data System (ADS)

    Zielinski, B.; Patorski, K.

    2008-12-01

    The aim of this paper is to analyze the accuracy of 2D fringe pattern denoising performed by two chosen methods using quasi-1D two-arm spin filter and 2D Discrete Wavelet Transform (DWT) signal decomposition and thresholding. The ultimate aim of this comparison is to estimate which algorithm is better suited for high-accuracy interferometric measurements. In spite of the fact that both algorithms are designed to minimize possible fringe blur and distortion, the evaluation of errors introduced by each algorithm is essential for proper estimation of their performance.

  19. 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.

  20. Solar Source Regions of Energetic 3He Emission

    NASA Astrophysics Data System (ADS)

    Mason, G. M.; Nitta, N. V.; Cohen, C. M.; Wiedenbeck, M. E.

    2012-12-01

    One of the surprising observations from the ACE mission has been the detection of energetic 3He emission occurring over multi-day periods. Previously observations of solar energetic 3He had detected short-lived "impulsive" energetic particle events which were associated with type III bursts and energetic electrons. The ACE observations were able to detect 3He at very low levels (<1% of 4He compared to ~10% in most earlier work) and this showed that the impulsive events often occurred during seemingly continuous multi-day periods of 3He emission. During solar active periods, 3He was present at 1 AU the majority of the time, giving evidence for either semi-continuous processes or else unresolved multiple small injections. The obvious injections during such periods were strongly associated with jet activity By adding STEREO and SDO observations we are seeking to extend the observational picture for these events. First, by following single 3He emitting regions from STEREO-B to ACE to STEREO-A we seek to examine for how long the 3He emission can continue, since any single spacecraft can be magnetically connected to a single region for only a few days and ACE often sees emission periods of that length. Second, by using SDO-AIA we seek to probe further the properties of the emitting regions to see if the previously reported association with jets is seen in events which we can now observe with greater resolution, sensitivity, and cadence than previously possible.

  1. JET (3He)-D scenarios relying on RF heating: survey of selected recent experiments

    SciTech Connect

    Van Eester, D.; Casati, A.; Crombe, K.; de la Luna, E.; Ericsson, G.; Felton, R.; Giroud, C.; Hjalmarsson, A.; Joffrin, E.; Kallne, J.; Kiptily, V.; Marinoni, A.; Santala, M.; Valisa, M.

    2009-03-01

    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. Alfv n 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] 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 also

  2. 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.

  3. Apparatus for deformation tests of solids in liquid 3He

    NASA Astrophysics Data System (ADS)

    Hashimoto, T.; Katakura, S.; Edagawa, K.; Takeuchi, S.; Suzuki, T.

    2000-07-01

    An apparatus for deformation of solids in liquid 3He is constructed. Either tensile deformation or compression of a specimen can be performed by exchanging the assemblies in the 3He pot which has a capacity of about 30 cm3. The pulling rod for transmitting load from the tensile testing machine to the specimen runs inside the outlet tube of 3He, being isolated from 4He bath and almost free from mechanical friction. To measure the change in flow stress with the supernormal transition of superconducting metals, a superconducting magnet is mounted outside of the vacuum chamber which separates the 3He pot and the 4He bath. Under an applied load for plastic deformation the system is stably operative down to 0.6 K, while the lowest temperature achieved is 0.5 K. Some results on Ta and NaCl are presented.

  4. 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

  5. Spectroscopic issues in optical polarization of 3He gas for Magnetic Resonance Imaging of human lungs

    NASA Astrophysics Data System (ADS)

    Dohnalik, T.; Głowacz, B.; Olejniczak, Z.; Pałasz, T.; Suchanek, M.; Wojna, A.

    2013-10-01

    The Magnetic Resonance Imaging (MRI) of human lungs for diagnostic purposes became possible by using nuclear spin hyperpolarized noble gases, such as 3He. One of the methods to polarize 3He is the Metastability Exchange Optical Pumping (MEOP), which up to now has been performed at low pressure of about 1 mbar and in low magnetic field below 0.1 T (standard conditions). The equilibrium nuclear polarization can reach up to 80%, but it is dramatically reduced during the subsequent gas compression to the atmospheric pressure that is necessary for the lungs examination. Further polarization losses occur during the transportation of the gas to the hospital scanner. It was shown recently that up to 50% polarization can be obtained at elevated pressure exceeding 20 mbar, by using magnetic field higher than 0.1 T (nonstandard conditions). Therefore, following the construction of the low-field MEOP polarizer located in the lab, a dedicated portable unit was developed, which uses the magnetic field of the 1.5 T MR medical scanner and works in the continuous-flow regime. The first in Poland MRI images of human lungs in vivo were obtained on the upgraded to 3He resonance frequency Siemens Sonata medical scanner. An evident improvement in the image quality was achieved when using the new technique. The paper shows how spectroscopic measurements of 3He carried out in various experimental conditions led both to useful practical results and to significant progress in understanding fundamental processes taking place during MEOP.

  6. 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.

  7. 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.

  8. 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)].

  9. Hyperpolarized 3He diffusion MRI and histology in pulmonary emphysema.

    PubMed

    Woods, Jason C; Choong, Cliff K; Yablonskiy, Dmitriy A; Bentley, John; Wong, Jonathan; Pierce, John A; Cooper, Joel D; Macklem, Peter T; Conradi, Mark S; Hogg, James C

    2006-12-01

    Diffusion MRI of hyperpolarized (3)He shows that the apparent diffusion coefficient (ADC) of (3)He gas is highly restricted in the normal lung and becomes nearly unrestricted in severe emphysema. The nature of this restricted diffusion provides information about lung structure; however, no direct comparison with histology in human lungs has been reported. The purpose of this study is to provide information about (3)He gas diffusivity in explanted human lungs, and describe the relationship between (3)He diffusivity and the surface area to lung volume ratio (SA/V) and mean linear intercept (L(m)) measurements--the gold standard for diagnosis of emphysema. Explanted lungs from patients who were undergoing lung transplantation for advanced COPD, and donor lungs that were not used for transplantation were imaged via (3)He diffusion MRI. Histological measurements were made on the same specimens after they were frozen in the position of study. There is an inverse correlation between diffusivity and SA/V (and a positive correlation between diffusivity and L(m)). An important result is that restricted (3)He diffusivity separated normal from emphysematous lung tissue more clearly than the morphometric analyses. This effect may be due to the smaller histologic sampling size compared to the MRI voxel sizes.

  10. Neutron interferometric measurement of the scattering length difference between the triplet and singlet states of n -3He

    NASA Astrophysics Data System (ADS)

    Huber, M. G.; Arif, M.; Chen, W. C.; Gentile, T. R.; Hussey, D. S.; Black, T. C.; Pushin, D. A.; Shahi, C. B.; Wietfeldt, F. E.; Yang, L.

    2014-12-01

    We report a determination of the n -3He scattering length difference Δ b'=b1'-b0'=[-5.411 ±0.031 (statistical)±0.039 (systematic)] fm between the triplet and singlet states using a neutron interferometer. This revises our previous result Δ b'=[-5.610 ±0.027 (statistical)±0.032 (systematic)] fm obtained using the same technique in 2008 [Huber et al., Phys. Rev. Lett. 102, 200401 (2009), 10.1103/PhysRevLett.102.200401; Huber et al., Phys. Rev. Lett. 103, 179903(E) (2009), 10.1103/PhysRevLett.103.179903]. This revision is attributable to a reanalysis of the 2008 experiment that now includes a systematic correction caused by magnetic-field gradients near the 3He cell which had been previously underestimated. Furthermore, we more than doubled our original data set from 2008 by acquiring 6 months of additional data in 2013. Both the new data set and a reanalysis of the older data are in good agreement. Scattering lengths of low-Z isotopes are valued for use in few-body nuclear effective field theories, provide important tests of modern nuclear potential models, and, in the case of 3He, aid in the interpretation of neutron scattering from quantum liquids. The difference Δ b' was determined by measuring the relative phase shift between two incident neutron polarizations caused by the spin-dependent interaction with a polarized 3He target. The target 3He gas was sealed inside a small, flat-windowed glass cell that was placed in one beam path of the interferometer. The relaxation of 3He polarization was monitored continuously with neutron transmission measurements. The neutron polarization and spin-flipper efficiency were determined separately using 3He analyzers and two different polarimetry analysis methods. A summary of the measured scattering lengths for n -3He with a comparison to nucleon interaction models is given.

  11. An Emergent Spin-Filter at the interface between Ferromagnetic and Insulating Layered Oxides

    NASA Astrophysics Data System (ADS)

    Liu, Yaohua

    2014-03-01

    Complex oxide heterostructures are of keen interest because modified bonding at the interfaces can give rise to fundamentally new phenomena and valuable functionalities. Particularly, an induced magnetization is widely observed at epitaxial interfaces between layered transition-metal oxides; however, much less effort has been spent on investigating how it affects the charge transport properties. To this end, we have studied magnetic tunneling junctions consisting of ferromagnetic manganite La0.7Ca0.3MnO3 (LCMO) and insulating cuprate PrBa2Cu3O7 (PBCO). Contrary to the typically observed steady increase of the tunnel magnetoresistance with decreasing temperature, this system exhibits an anomalous decrease at low temperatures. Polarized neutron reflectometry (PNR) and x-ray magnetic circular dichroism (XMCD) studies on LCMO/PBCO/LCMO trilayers show that the saturation magnetization of the LCMO contacts increase as the temperature decreases. In other words, degradation of the ferromagnetic contacts is ruled out as a cause. Interestingly, there exists induced net Cu moments, which indicates that the spin degeneracy of the conduction band of the PBCO barrier is lifted and thus the barrier becomes spin selective. Our calculations, within the Wentzel-Kramers-Brillouin approximation, show that the complex temperature dependence can arise from a competition between the high positive spin polarization of the manganite electrodes and a negative spin-filter effect from the interfacial Cu magnetization. This work illustrates that the interface-induced magnetization in layered oxide heterostructures can have non-trivial effects on the macroscopic transport properties. Work performed in collaboration with FA Cuellar, Z Sefrioui, C Leon, J Santamaria (Universidad Complutense de Madrid), JW Freeland, SGE te Velthuis (ANL) and MR Fitzsimmons (LANL). Work at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Basic Energy Sciences under contract no

  12. 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).

  13. Overview of the parity violation measurement of n+3 He --> p + t

    NASA Astrophysics Data System (ADS)

    Coppola, Christopher; n3He Collaboration

    2016-03-01

    The hadronic weak interaction remains the least well-understood of the weak interactions. There are multiple models with effective degrees of freedom characterizing its spin and isospin dependence. Measuring the strength of this interaction is difficult due to the much larger strong interaction between nucleons. However, parity violation in few-body reactions allows isolation of weak contributions on the order of 10-7 from the strong background. The size of parity violating asymmetry in the reaction n+3 He is expected to be of this order. The experiment has fininshed taking data from a 3He target in a polarized pulsed neutron beam at the Spallation Neutron Source at Oak Ridge National Laboratory. The expected precision of the asymmetry calculations is on the order of 10-8, and we are now in the analysis phase.

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

    NASA Technical Reports Server (NTRS)

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

  15. 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.

  16. Feasibility of neutron diffraction on solid 3He

    NASA Astrophysics Data System (ADS)

    Siemensmeyer, K.; Schuberth, E. A.; Adams, E. D.; Takano, Y.; Guckelsberger, K.

    2000-07-01

    We have investigated the feasibility of neutron diffraction from solid 3He. The experiment will be performed at the HMI, first aiming for the properties of the antiferromagnetic ordering in the BCC phase and the ferromagnetic order in the HCP phase. Signal and beam heating considerations are essential to account for the enormous neutron absorption cross section of 3He. The study shows that neutron diffraction and transmission experiments are possible, relying on the experience gained from the neutron diffraction experiments on Cu and Ag at nanokelvin temperatures. A pressure cell has been developed which complies with the conflicting demands arising from the neutron and ultralow temperature aspects of the experiment. This work is a first step in an extensive effort to characterize 3He by neutron diffraction.

  17. 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.

  18. 3He Neutron Detector Pressure Effect and Comparison to Models

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.; Stromswold, David C.; Woodring, Mitchell L.

    2010-01-14

    Reported here are the results of measurements performed to determine the efficiency of 3He filled proportional counters as a function of gas pressure in the SAIC system. Motivation for these measurements was largely to validate the current model of the SAIC system. Those predictions indicated that the neutron detection efficiency plotted as a function of pressure has a simple, logarithmic shape. As for absolute performance, the model results indicated the 3He pressure in the current SAIC system could not be reduced appreciably while meeting the current required level of detection sensitivity. Thus, saving 3He by reducing its pressure was predicted not to be a viable option in the current SAIC system.

  19. Neutron-scattering experiment on solid 3He

    NASA Astrophysics Data System (ADS)

    Mat'aš, S.; Bat'ko, I.; Boyko, V.; Schöttl, S.; Siemensmeyer, K.; Raasch, S.; Radulov, I.; Adams, E. D.; Scherline, T. E.

    The central aim of our work is the characterisation of magnetic and crystallographic properties of solid 3He on a microscopic scale. This can only be achieved using neutron-diffraction techniques. The potential of neutron methods in magnetism and their application to nuclear magnetism is well known. They were very successful in the recent investigation of spontaneous nuclear order in copper and silver. The high neutron absorption cross section makes the application of neutron diffraction in solid 3He very difficult - but a careful feasibility study of diffraction experiments shows that new results of fundamental importance in the field of magnetism may be gained.

  20. Anisotropic Phases of Superfluid 3He in Compressed Aerogel

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    It has been shown that the relative stabilities of various superfluid states of 3He 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 3He 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.

  1. Ay0 Measurement from Quasi-Elastic 3He ↑ (e ,e' n) Scattering at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Long, Elena; Jefferson Lab Hall A Collaboration

    2016-03-01

    Due to the lack of free neutron targets, studies of the structure of the neutron are typically made by scattering electrons from either 2H or 3He targets. In order to extract useful neutron information from a 3He target, one must first understand how the neutron in a 3He system differs from a free neutron by taking into account nuclear effects such as final state interactions and meson exchange currents. The target single spin asymmetry Ay0 is an ideal probe of such effects, as any deviation from zero indicates effects beyond plane wave impulse approximation. When nuclear effects within the 3He wave function are taken into account, calculations show that this asymmetry can become large (> 50 %). New measurements of the target single spin asymmetry Ay0 were made at Jefferson Lab using the quasi-elastic 3He↑ (e ,e' n) reaction. The measured asymmetry decreases by over two orders of magnitude, from > 70 % at Q2 = 0 . 1 (GeV/c)2 to nearly zero at Q2 = 1 (GeV/c)2, providing evidence of the dominance and fall-off of nuclear effects when studying neutron structure by electron scattering from 3He. Details of the measurement will be presented.

  2. Simulation studies of instrumental artifacts on spin I=1 double quantum filtered NMR spectroscopy

    PubMed Central

    Sun, Cheng; Boutis, Gregory S.

    2010-01-01

    We report on the results of a simulation based study of the effect of various experimental artifacts for spin I=1 double quantum filtered NMR. The simulation captures the effects of static field inhomogeneity, finite pulse widths, phase errors, transients and radio frequency inhomogeneity. We simulated the spectral distortions introduced under these errors for four, eight and sixteen step phase cycles that are well known in the NMR community. The dominating pulse errors are radio frequency field inhomogeneity and antisymmetric pulse transients. These errors result in the reduction of signal intensity as well as an introduction of distortions in the detected double quantum filtered spectrum. Using the simulation tool we studied the improvement one obtains when implementing a sixteen step phase cycle over a four step phase cycle. The results indicate that implementing a sixteen step phase cycle over an eight or four step phase cycle does not result in a significant reduction in the DQF intensity loss, or reduction in spectral distortions for antisymmetric transients. PMID:20451432

  3. 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

  4. Stability and Spectra of Small 3He-4He Clusters

    NASA Astrophysics Data System (ADS)

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

    Diffusion Monte Carlo calculations have been systematically performed to analyze the stability of small mixed 3He-4He clusters, as well as their excitation spectra. The picture that emerges is that of systems with strong shell effects whose binding and excitation energies are essentially determined by the monopole properties of an effective Hamiltonian.

  5. {sup 3}He neutral current detectors at SNO

    SciTech Connect

    Elliott, S.R.; Browne, M.C.; Doe, P.J.

    1998-09-01

    The flux of solar neutrinos measured via charged and neutral current interactions can provide a model independent test of neutrino oscillations. Since the Sudbury Neutrino Observatory uses heavy water as a target, it has a large sensitivity to both interactions. A technique for observing the neutral current breakup of the deuteron using {sup 3}He proportional counters is described.

  6. 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.

  7. 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.

  8. Improved neutron-gamma discrimination for a 3He neutron detector using subspace learning methods

    DOE PAGES

    Wang, C. L.; Funk, L. L.; Riedel, R. A.; ...

    2017-02-10

    3He gas based neutron linear-position-sensitive detectors (LPSDs) have been applied for many neutron scattering instruments. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio on the orders of 105-106. The NGD ratios of 3He detectors need to be improved for even better scientific results from neutron scattering. Digital Signal Processing (DSP) analyses of waveforms were proposed for obtaining better NGD ratios, based on features extracted from rise-time, pulse amplitude, charge integration, a simplified Wiener filter, and the cross-correlation between individual and template waveforms of neutron and gamma events. Fisher linear discriminant analysis (FLDA) and threemore » multivariate analyses (MVAs) of the features were performed. The NGD ratios are improved by about 102-103 times compared with the traditional PHA method. Finally, our results indicate the NGD capabilities of 3He tube detectors can be significantly improved with subspace-learning based methods, which may result in a reduced data-collection time and better data quality for further data reduction.« less

  9. Acceleration of 3HE and heavy ions at interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Desai, M. I.; Mason, G. M.; Dwyer, J. R.; Mazur, J. E.; Smith, C. W.; Koug, R. M.

    2001-08-01

    We have surveyed the 0.5-2.0 MeV nucleon-1 ion composition of 56 interplanetary shocks (IP) observed with the Ultra-Low-Energy Isotope Spectrometer (ULEIS) on board the Advanced Composition Explorer (ACE) from 1997 October 1 through 2000 November 30. Our results show the first ever measurement (25 cases) of 3 He ions being accelerated at IP shocks. The 3 He/4 He ratio at the 25 shocks exhibited a wide range of values between 0.00140.24; the ratios were enhanced between factors of ~3-600 over the solar wind value. During the survey period, the occurrence probability of 3 He-rich shocks increased with rising solar activity as measured in terms of the daily occurrence rates of sunspots and X-ray flares. The 3 He enhancements at IP shocks cannot be attributed to rigidity dependent acceleration of solar wind ions and are better explained if the shocks accelerate ions from multiple sources, one being remnant impulsive solar flare material enriched in 3 He ions. Our results also indicate that the contribution of impulsive flares to the seed population for IP shocks varies from event to event, and that the interplanetary medium is being replenished with impulsive material more frequently during periods of increased solar activity. 1. Introduction Enhancements in the intensities of energetic ions associated with transient interplanetary (IP) shocks have been observed routinely at 1 AU since the 1960's (e.g., Reames 1999). It is presently believed that the majority of such IP shocks are driven by fast coronal mass ejections or CMEs as they propagate through interplanetary space (e.g., Gosling 1993), and that the associated ion intensity enhancements are due to diffusive shock acceleration of solar wind ions (Lee 1983; Jones and Ellison 1991; Reames 1999). However, the putative solar wind origin of the IP-shock accelerated ions is based on composition measurements associated with a very limited number of individual IP shocks (Klecker et al. 1981; Hovestadt et al. 1982; Tan et

  10. Evidence for Split NMR Lines in Ferromagnetic 3He Films

    NASA Astrophysics Data System (ADS)

    Guo, Lei; Zhang, Jinshan; Du, Yuliang; Gould, C. M.; Bozler, H. M.

    2006-09-01

    In earlier experiments on ferromagnetic 3He films, we observed a complex lineshape due in part to the dipolar field generated by polarization of the 3He nuclei. Much of the complex lineshape can be explained by the known distribution of the Grafoil platelets. However, there remained some evidence for a split NMR line at some temperatures. In our new experiments on ZYX grade exfoliated graphite where the size of individual platelets is much larger and the angular distribution is three times smaller, this splitting has become more evident over a wider range of temperatures. Now it is clear that the complex lineshape includes two peaks along with remaining orientation effects. We also find that roughly 2% of our signal comes from randomly oriented platelets. We present the details of our model for analyzing these lineshapes and the experimental results for the line splitting at several coverages in the ferromagnetic range. We discuss the possible sources of this line splitting.

  11. Proton polarization from π+ absorption in 3He

    NASA Astrophysics Data System (ADS)

    Maytal-Beck, S.; Aclander, J.; Altman, A.; Ashery, D.; Hahn, H.; Moinester, M. A.; Rahav, A.; Feltham, A.; Jones, G.; Pavan, M.; Sevior, M.; Hutcheon, D.; Ottewell, D.; Smith, G. R.; Niskanen, J. A.

    1992-05-01

    We present the first polarization measurements for pion absorption on a nucleus heavier than the deuteron. The polarization of protons resulting from π+ absorption in the 3He was measured at bombarding energies of 120 and 250 MeV. Protons from absorption in a quasideuteron were selected by applying kinematical constraints. A significant discrepancy was observed between the experimental results and theoretical predictions. At 120 MeV the measured polarizations for 3He are consistent with those of the deuteron. At 250 MeV the angular distribution of the polarization is significantly different than for the deuteron, showing sensitivity to the nuclear density, and thus may be sensitive to short range correlations between nucleons.

  12. Overview of the n3He Experiment and Target Chamber

    NASA Astrophysics Data System (ADS)

    McCrea, Mark; n3He Collaboration

    2017-01-01

    The n3He Experiment aims to measure the parity-violating asymmetry in the direction of proton emission relative to the initial neutron polarization direction in the reaction n-> +3 He -> T + p + 765 keV to a high precision. The size of the asymmetry is estimated to be in the range - 9 . 5 - 2 . 5 ×10-8 , and our goal statistical accuracy is 2 ×10-8 . The experiment ran at the Spallation Neutron Source with data taking completing at the end of 2015. The experiment used a Helium-3 ionization chamber as the combined target and detector. Data analysis is underway and is currently in an advanced stage

  13. Reaction mechanism and characteristics of T20 in d+3He backward elastic scattering at intermediate energies

    NASA Astrophysics Data System (ADS)

    Tanifuji, M.; Ishikawa, S.; Iseri, Y.; Uesaka, T.; Sakamoto, N.; Satou, Y.; Itoh, K.; Sakai, H.; Tamii, A.; Ohnishi, T.; Sekiguchi, K.; Yako, K.; Sakoda, S.; Okamura, H.; Suda, K.; Wakasa, T.

    2000-02-01

    For backward elastic scattering of deuterons by 3He, cross sections σ, and tensor analyzing power T20 are measured at Ed=140-270 MeV. The data are analyzed by the plane wave impluse approximation (PWIA) and by the general formula which includes virtual excitations of other channels, with the assumption of the proton transfer from 3He to the deuteron. Using 3He wave functions calculated by the Faddeev equation, the PWIA describes global features of the experimental data, while the virtual excitation effects are important for quantitative fits to the T20 data. Theoretical predictions on T20, Kyy (polarization transfer coefficient), and Cyy (spin correlation coefficient) are provided up to GeV energies.

  14. Internal Magnus effects in superfluid 3He-A

    NASA Astrophysics Data System (ADS)

    Salmelin, R. H.; Salomaa, M. M.; Mineev, V. P.

    The orbital angular momentum of the coherently aligned Cooper pairs in superfluid (3)He-A is transmitted to an object immersed in the condensate. The authors evaluate the quasiparticle-scattering asymmetry experienced by a negative ion; this leads to a measurable, purely quantum-mechanical Magnus force deflecting the ion's trajectory. Close to T(sub c), possible hydrodynamic Magnus effects are smaller by the factor delta sub A/(k sub B)(T sub c).

  15. Hard Two-body Photodisintegration of ^3He

    SciTech Connect

    Pomerantz, Ishay Ari; Ilieva, Yordanka Yordanova; Gilman, Ronald; Higinbotham, Douglas W.; Piasetzky, Eliazer Israel; Strauch, Steffen

    2013-06-01

    We have measured cross sections for the {gamma}+{sup 3}He->p+d reaction at photon energies of 0.4 - 1.4 GeV and a center-of-mass angle of 90 deg. 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.

  16. 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.

  17. 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%.

  18. Resonant quasiparticle-ion scattering in anisotropic superfluid 3He

    NASA Astrophysics Data System (ADS)

    Salmelin, R. H.; Salomaa, M. M.

    1990-03-01

    Low-energy excitations in quantum fluids are most directly encountered by ions. In the superfluid phases of 3He the relevant elementary excitations are Bogoliubov quasiparticles, which undergo repeated scattering off an ion in the presence of a divergent density of states. We present a quantum-mechanical calculation of the resonant 3He quasiparticle-scattering-limited mobility for negative ions in the anisotropic bulk 3A (A phase) and 3P (polar phase) that is exact when the quasiparticles scatter elastically. We develop a numerical scheme to solve the singular equations for quasiparticle-ion scattering in the A and P phases. Both of these superfluid phases feature a uniaxially symmetric order parameter but distinct topology for the magnitude of the energy gap on the Fermi sphere, i.e., points versus lines of nodes. In particular, the perpetual orbital circulation of Cooper pairs in 3A results in a novel, purely quantum-mechanical intrinsic Magnus effect, which is absent in the polar phase, where Cooper pairs possess no spontaneous orbital angular momentum. This is of interest also for transport properties of heavy-fermion superconductors. We discuss the 3He quasiparticle-ion cross sections, which allow one to account for the mobility data with essentially no free parameters. The calculated mobility thus facilitates an introduction of ``ion spectroscopy'' to extract useful information on fundamental properties of the superfluid state, such as the temperature dependence of the energy gap in 3A.

  19. 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

    2016-01-08

    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.

  20. 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.

  1. 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.

  2. 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.

  3. The 3H-3He Charge Radii Difference

    SciTech Connect

    Myers, Luke S.; Arrington, John R.; Higinbotham, Douglas 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.

  4. 3He film flow on a round rim beaker

    NASA Astrophysics Data System (ADS)

    Steel, S. C.; Harrison, J. P.; Zawadzki, P.; Sachrajda, A.

    1994-06-01

    The superfluid properties of thin (100 150 nm) of3He were investigated by measuring the rate at which a beaker of liquid3He emptied itself through the adsorbed film, with the film thickness δ decreasing as the level dropped. A beaker rim with a semicircular cross-section was used to provide a well defined geometry and to avoid the effects of small scratches that may have affected earlier experiments. The film thicknesses were determined by Atkins' oscillaton measurements of4He films on the same surface. The superfluid transition temperature in the film T {/c F } was suppressed below the bulk value T {/c B }, and was close to being described by 2δ/ξ( T {/c F }) = π, as expected for A-phase. The critical current density was more than an order of magnitude smaller than expected for pair-breaking. When a4He monolayer was adsorbed on the substrate, there was no suppresson of T {/c F }.

  5. Effect of Aerogel Anisotropy in Superfluid 3He-A

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Two theories have been advanced to describe the effects of anisotropic impurity introduced by stretched silica aerogel on the orientation of the orbital angular momentum l& circ; in superfluid 3He-A. These theories disagree on whether the anisotropy will orient l& circ; perpendicular[2] or parallel[3] to the strain axis. In order to examine this question we have produced and characterized a homogeneous aerogel sample with uniaxial anisotropy introduced during growth, corresponding to stretching of the aerogel. These samples have been shown to stabilize two new chiral states;[4] the higher temperature state being the subject of the present study. Using pulsed NMR we have performed experiments on 3He-A imbibed in this sample in two orientations: strain parallel and perpendicular to the applied magnetic field. From the NMR frequency shifts as a function of tip angle and temperature, we find that the angular momentum l& circ; is oriented along the strain axis, providing evidence for the theory advanced by Sauls. This work was supported by the National Science Foundation, DMR-1103625.

  6. Pion absorption on 3He at low energies

    NASA Astrophysics Data System (ADS)

    Hahn, H.; Altman, A.; Ashery, D.; Gefen, G.; Gill, D. R.; Johnson, R. R.; Levy-Nathansohn, R.; Moinester, M. A.; Sevior, M.; Trelle, R. P.

    1996-03-01

    The reactions 3He(π+,pp)p and 3He(π-,pn)n were studied at 37.0 MeV by coincidence detection of two nucleons. The differential cross sections were separated to two-nucleon (σ2N), three-nucleon (σ3N), and final-state interaction (σFSI) components. For π+, the σ2N angular distribution is symmetric about 90°, and the total cross section is 1.5 times the cross section measured for d(π+,pp). For π-, the angular distribution is asymmetric (backward peaked). The asymmetry increases with decreasing energy, indicating increasing pion s-wave contribution at lower energies. The fraction of the cross section induced by s-wave pions as calculated by a partial wave amplitude analysis is 13%. The measured total cross sections are σ2N(π-)=0.85+/-0.08 mb and σ2N(π+)=7.9+/-0.5 mb; σ3N(π-)=1.6+/-0.7 mb and σ3N(π+)=1.3+/-0.3 mb. A new evaluation of σ3N at Tπ=62.5 and 82.8 MeV is given, using data from an earlier experiment. The cross sections leading to the two-nucleon final-state interaction at Tπ=37.0 MeV are also estimated.

  7. Interaction of Hydrogen Atoms with Helium Films: Sticking Probabilities for H on 3He and 4He, and the Binding Energy of H on 3He

    NASA Astrophysics Data System (ADS)

    Jochemsen, R.; Morrow, M.; Berlinsky, A. J.; Hardy, W. N.

    1981-09-01

    Magnetic resonance at 1420 MHz in zero magnetic field and for 0.063He, the rate constant for recombination and the frequency shift for H on 3He, and the sticking probability for H on 3He and 4He. The binding energy for H on liquid 3He is found to be 0.42+/-0.05 K, and the sticking probabilities are 0.035 for H on 4He and 0.016 for H on 3He.

  8. Crossover from fermi liquid to classical behavior of normal /sup 3/He in the model of almost localized fermions

    SciTech Connect

    Seiter, K.; Gros, C.; Rice, T.M.; Veda, K.; Vollhardt, D.

    1986-08-01

    A phenomenological extension of the model of almost localized fermions to finite temperatures is presented. It is used to calculate thermodynamic properties of the normal state of /sup 3/He. No new adjustable parameters are introduced and the effective interaction strength is the same as used by Vollhardt. A good qualitative description of the crossover from Fermi liquid to classical behavior in the specific heat, spin susceptibility, and temperature-dependent pressure (or equivalently thermal expansion) is obtained. In particular, key results, such as the change in specific heat when the spin entropy saturates and the change from thermal expansion to thermal contraction at low temperatures are reproduced.

  9. 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.

  10. Spin superfluidity and coherent spin precession

    NASA Astrophysics Data System (ADS)

    Bunkov, Yuriy M.

    2009-04-01

    The spontaneous phase coherent precession of the magnetization in superfluid 3He-B was discovered experimentally in 1984 at the Institute for Physical Problems, Moscow by Borovik-Romanov, Bunkov, Dmitriev and Mukharsky and simultaneously explained theoretically by Fomin (Institut Landau, Moscow). Its formation is a direct manifestation of spin superfluidity. The latter is the magnetic counterpart of mass superfluidity and superconductivity. It is also an example of the Bose-Einstein condensation of spin-wave excitations (magnons). The coherent spin precession opened the way for investigations of spin supercurrent magnetization transport and other related phenomena, such as spin-current Josephson effect, process of phase slippage at a critical value of spin supercurrent, spin-current vortices, non-topological solitons (analogous to Q-balls in high energy physics) etc. New measuring techniques based on coherent spin precession made the investigation of mass counterflow and mass vortices possible owing to the spin-mass interaction. New phenomena were observed: mass-spin vortices, the Goldstone mode of the mass vortex with non-axisymmetric core, superfluid density anisotropy etc. Different types of coherent spin precession were later found in superfluid 3He-A and 3He-B confined in anisotropic aerogel, in the states with counterflow and in 3He with reduced magnetization. Finally, spin superfluidity investigations developed the basis for a modern investigation of electron spin supercurrent and spintronics.

  11. 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

  12. Sub-nanometer atomic layer deposition for spintronics in magnetic tunnel junctions based on graphene spin-filtering membranes.

    PubMed

    Martin, Marie-Blandine; Dlubak, Bruno; Weatherup, Robert S; Yang, Heejun; Deranlot, Cyrile; Bouzehouane, Karim; Petroff, Frédéric; Anane, Abdelmadjid; Hofmann, Stephan; Robertson, John; Fert, Albert; Seneor, Pierre

    2014-08-26

    We report on the successful integration of low-cost, conformal, and versatile atomic layer deposited (ALD) dielectric in Ni–Al2O3–Co magnetic tunnel junctions (MTJs) where the Ni is coated with a spin-filtering graphene membrane. The ALD tunnel barriers, as thin as 0.6 nm, are grown layer-by-layer in a simple, low-vacuum, ozone-based process, which yields high-quality electron-transport barriers as revealed by tunneling characterization. Even under these relaxed conditions, including air exposure of the interfaces, a significant tunnel magnetoresistance is measured highlighting the robustness of the process. The spin-filtering effect of graphene is enhanced, leading to an almost fully inversed spin polarization for the Ni electrode of −42%. This unlocks the potential of ALD for spintronics with conformal, layer-by-layer control of tunnel barriers in magnetic tunnel junctions toward low-cost fabrication and down-scaling of tunnel resistances.

  13. 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.

  14. 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.

  15. Perspectives of hyperpolarized noble gas MRI beyond 3He

    NASA Astrophysics Data System (ADS)

    Lilburn, David M. L.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2013-04-01

    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.

  16. 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.

  17. Alpha Backgrounds in the SNO ^3He Proportional Counter Array

    NASA Astrophysics Data System (ADS)

    Stonehill, Laura

    2006-04-01

    The Sudbury Neutrino Observatory (SNO) has recently deployed an array of proportional counters known as Neutral Current Detectors (NCDs) to detect thermalized neutrons via the ^3He(n,p)^3H reaction. The primary physics background to the neutron-capture signal is alpha particle emission from uranium- and thorium-chain decays in the NCD walls. The expected capture rate of neutrons from the neutral-current neutrino reaction on deuterium is three per day and the intrinsic alpha background rate is approximately 250 alphas per day. Fewer than 10% of these alphas fall into the energy range where neutron-capture signals occur, and a substantial number of these can be eliminated by pulse-shape analysis. This talk will focus on measurements of the alpha backgrounds in the NCDs and the extent to which these alphas contaminate the neutron-capture signal region.

  18. Realization of administration unit for 3He with gas recycling

    NASA Astrophysics Data System (ADS)

    Güldner, M.; Becker, S.; Friesenecker, A.; Gast, K. K.; Heil, W.; Karpuk, S.; Otten, E. W.; Rivoire, J.; Salhi, Z.; Scholz, A.; Schreiber, L. M.; Terekhov, M.; Weiss, P.; Wolf, U.; Zentel, J.

    2011-06-01

    Hyperpolarized (HP) noble gases (3He,129Xe) are used for MR-imaging of the lung. In the majority of case the HP gas is filled in Tedlarbags and directly inhaled by the patients. Starting from an earlier pilot device, an administration unit was built respectively to the Medical Devices Law to administer patients HP noble gas boli in defined quantities and at a predefined time during inspiration with high reproducibility and reliability without reducing MR-quality. The patient's airflows are monitored and recorded. It is possible to use gas admixtures, measure the polarization on-line and collect the exhaled gas for later recycling. The first images with healthy volunteers were taken with this setup in a clinical study. Current results will be presented.

  19. {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.

  20. On the Nambu fermion-boson relations for superfluid 3He

    NASA Astrophysics Data System (ADS)

    Sauls, J. A.; Mizushima, Takeshi

    2017-03-01

    Superfluid 3He is a spin-triplet (S =1 ), p -wave (L =1 ) BCS condensate of Cooper pairs with total angular momentum J =0 in the ground state. In addition to the breaking of U(1) gauge symmetry, separate spin or orbital rotation symmetry is broken to the maximal subgroup SO (3) S×SO (3) L→SO(3 ) J . The fermions acquire mass mF≡Δ , where Δ is the BCS gap. There are also 18 bosonic excitations: 4 Nambu-Goldstone modes and 14 massive amplitude Higgs modes. The bosonic modes are labeled by the total angular momentum J ∈{0 ,1 ,2 } , and parity under particle-hole symmetry c =±1 . For each pair of angular momentum quantum numbers J ,Jz , there are two bosonic partners with c =±1 . Based on this spectrum, Nambu proposed a sum rule connecting the fermion and boson masses for BCS-type theories, which for 3He-B is MJ,+ 2+MJ,- 2=4 mF2 for each family of bosonic modes labeled by J , where MJ ,c is the mass of the bosonic mode with quantum numbers (J ,c ) . The Nambu sum rule (NSR) has recently been discussed in the context of Nambu-Jona-Lasinio models for physics beyond the standard model to speculate on possible partners to the recently discovered Higgs boson at higher energies. Here, we point out that the Nambu fermion-boson mass relations are not exact. Corrections to the bosonic masses from (i) leading-order strong-coupling corrections to BCS theory, and (ii) polarization of the parent fermionic vacuum lead to violations of the sum rule. Results for these mass corrections are given in both the T →0 and T →Tc limits. We also discuss experimental results, and theoretical analysis, for the masses of the Jc=2± Higgs modes and the magnitude of the violation of the NSR.

  1. The magnetic and quantum transport properties of benzene-vanadium-borazine mixed sandwich clusters: a new kind of spin filter.

    PubMed

    Yang, Zhi; Liu, Shaoding; Liu, Xuguang; Yang, Yongzhen; Li, Xiuyan; Xiong, Shijie; Xu, Bingshe

    2012-11-07

    Using density functional theory and the non-equilibrium Green's function technique, we performed theoretical investigations on the magnetic and quantum transport properties of benzene-vanadium-borazine mixed organic/inorganic ligand sandwich clusters. The calculated results show that these finite sandwich clusters coupled to Ni electrodes exhibit novel quantum transport properties such as half-metallicity, negative differential resistance and spin-reversal effect, and can be viewed as a new kind of spin filter. However, for the infinite molecular wire, the ground state was identified as a ferromagnetic semiconductor with high stability. These findings suggest that the mixed organic/inorganic ligand sandwich clusters and molecular wires are promising materials for application in molecular electronics and spintronics.

  2. 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.

  3. 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.

  4. Pure absorption electron spin echo envelope modulation spectra by using the filter-diagonalization method for harmonic inversion.

    PubMed

    Jeschke, G; Mandelshtam, V A; Shaka, A J

    1999-03-01

    Harmonic inversion of electron spin echo envelope (ESEEM) time-domain signals by filter diagonalization is investigated as an alternative to Fourier transformation. It is demonstrated that this method features enhanced resolution compared to Fourier-transform magnitude spectra, since it can eliminate dispersive contributions to the line shape, even if no linear phase correction is possible. Furthermore, instrumental artifacts can be easily removed from the spectra if they are narrow either in time or frequency domain. This applies to echo crossings that are only incompletely eliminated by phase cycling and to spurious spectrometer frequencies, respectively. The method is computationally efficient and numerically stable and does not require extensive parameter adjustments or advance knowledge of the number of spectral lines. Experiments on gamma-irradiated methyl-alpha-d-glucopyranoside show that more information can be obtained from typical ESEEM time-domain signals by filter-diagonalization than by Fourier transformation.

  5. Effect of an intermediate bcc phase on the evolution of superfluid inclusions in an hcp 3He-4He matrix

    NASA Astrophysics Data System (ADS)

    Birchenko, A. P.; Mihin, N. P.; Neoneta, A. S.; Rudavskii, E. Ya.; Fysun, Ya. Yu.

    2016-09-01

    Pulsed NMR is used to study the evolution of liquid inclusions formed in an hcp matrix during rapid cooling of a 3He-4He solution containing 1.05% 3He. The diffusion coefficient of 3He in the liquid inclusions as they evolve is measured by a spin echo technique with two probe pulses. The measurements were made at 1.67 K, which corresponds to the region of the bcc phase in the phase diagram, and at 1.38 K, where the bcc phase is absent. It is found that during the evolution in both cases, the liquid inclusions are smaller than the diffusion length and diffusion is restricted. The measured coefficient of restricted diffusion made it possible to determine the characteristic size of the inclusions. In the first case, during the evolution of the liquid inclusions an intermediate bcc phase in the form of dendrites develops and separates the liquid inclusions into a mass of fine droplets. Because of the rapid growth of the bcc phase, the size of the droplets decreases rapidly and the process ends with the disappearance of the bcc phase and the formation of an amorphous state. The results derived from the measured diffusion coefficient correlate with the behavior of the spin-lattice relaxation time in this kind of system. In the second case, at a lower temperature, the bcc phase does not develop and the evolution of the liquid inclusions is accompanied by a very slow reduction in their size until their complete solidification.

  6. Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

    DOE PAGES

    Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; ...

    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

  7. Pure second harmonic current-phase relation in spin-filter Josephson junctions.

    PubMed

    Pal, Avradeep; Barber, Z H; Robinson, J W A; Blamire, M G

    2014-01-01

    Higher harmonics in current-phase relations of Josephson Junctions are predicted to be observed when the first harmonic is suppressed. Conventional theoretical models predict higher harmonics to be extremely sensitive to changes in barrier thickness, temperature, and so on. Here we report experiments with Josephson junctions incorporating a spin-dependent tunnelling barrier, revealing a current-phase relation for highly spin polarized barriers that is purely second harmonic in nature and is insensitive to changes in barrier thickness. This observation implies that the standard theory of Cooper pair transport through tunnelling barriers is not applicable for spin-dependent tunnelling barriers.

  8. Hard photodisintegration of 3He into a p d pair

    NASA Astrophysics Data System (ADS)

    Maheswari, Dhiraj; Sargsian, Misak M.

    2017-02-01

    The recent measurements of high energy photodisintegration of a 3He nucleus to a p d pair at 90∘ center of mass demonstrated an energy scaling consistent with the quark counting rule with an unprecedentedly large exponent of s-17. To understand the underlying mechanism of this process, we extended the theoretical formalism of the hard rescattering mechanism (HRM) to calculate the γ 3He→p d reaction. In HRM the incoming high energy photon strikes a quark from one of the nucleons in the target which subsequently undergoes hard rescattering with the quarks from the other nucleons, generating a hard two-body system in the final state of the reaction. Within the HRM we derived the parameter-free expression for the differential cross section of the reaction, which is expressed through the 3He→p d transition spectral function, the cross section of hard p d →p d scattering, and the effective charge of the quarks being interchanged during the hard rescattering process. The numerical estimates of all these factors resulted in the magnitude of the cross section, which is surprisingly in good agreement with the data.

  9. 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}.

  10. 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.

  11. 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.

  12. 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.

  13. Applying filtering for determining the angular orientation of spinning objects during interference

    NASA Astrophysics Data System (ADS)

    Kartsan, I. N.; Fateev, Y. L.; Tyapkin, V. N.; Dmitriev, D. D.; Goncharov, A. E.; Zelenkov, P. V.; Kovalev, I. V.

    2016-11-01

    This article discusses the application of user navigation equipment of satellite radionavigation systems (GLONASS/GPS) for measuring the inclination of the aerial axis of rotation. The authors have demonstrated that the required accuracy of the angular inclination is achieved only in a relative phase mode, which is not always feasible. The application of filtering for measured parameters of navigation equipment has namely been used for planimetric coordinates. Filtering is performed using the second order Kalman filter. It has significant effect; thus, even at a speed of 1 rpm, there is no disruption in the autonomous coded mode; for the relative phase mode, the required accuracy is achieved at 3 rpm.

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

    NASA Astrophysics Data System (ADS)

    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 He3 atoms bound to a cluster of He4 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.

  15. The Effects of Negative Differential Resistance, Bipolar Spin-Filtering, and Spin-Rectifying on Step-Like Zigzag Graphene Nanoribbons Heterojunctions with Single or Double Edge-Saturated Hydrogen

    NASA Astrophysics Data System (ADS)

    Wang, Lihua; Zhao, Jianguo; Ding, Bingjun; Guo, Yong

    2017-01-01

    In this study, we investigated the spin-resolved transport aspects of step-like zigzag graphene ribbons (ZGNRs) with single or double edge-saturated hydrogen using a method that combined the density functional theory with the nonequilibrium Green's function method under the local spin density approximation. We found that, when the ZGNR-based heterojunctions were in a parallel or antiparallel layout, negative differential resistance, the maximum bipolar spin-filtering, and spin-rectifying effects occurred synchronously except for the case of spin-down electrons in the parallel magnetic layouts. Interestingly, these spin-resolved transport properties were almost unaffected by altering the widths of the two component ribbons. Therefore, step-like ZGNR heterojunctions are promising for use in designing high-performance multifunctional spintronic devices.

  16. 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.

  17. Structure, magnetic ordering, and spin filtering efficiency of NiFe{sub 2}O{sub 4}(111) ultrathin films

    SciTech Connect

    Matzen, S.; Moussy, J.-B.; Wei, P.; Gatel, C.; Cezar, J. C.; Arrio, M. A.; Sainctavit, Ph.; Moodera, J. S.

    2014-05-05

    NiFe{sub 2}O{sub 4}(111) ultrathin films (3–5 nm) have been grown by oxygen-assisted molecular beam epitaxy and integrated as effective spin-filter barriers. Structural and magnetic characterizations have been performed in order to investigate the presence of defects that could limit the spin filtering efficiency. These analyses have revealed the full strain relaxation of the layers with a cationic order in agreement with the inverse spinel structure but also the presence of antiphase boundaries. A spin-polarization up to +25% has been directly measured by the Meservey-Tedrow technique in Pt(111)/NiFe{sub 2}O{sub 4}(111)/γ-Al{sub 2}O{sub 3}(111)/Al tunnel junctions. The unexpected positive sign and relatively small value of the spin-polarization are discussed, in comparison with predictions and previous indirect tunnelling magnetoresistance measurements.

  18. Steady-state free precession with hyperpolarized 3He: Experiments and theory

    NASA Astrophysics Data System (ADS)

    Wild, Jim M.; Teh, Kevin; Woodhouse, Neil; Paley, Martyn N. J.; Fichele, Stan; de Zanche, Nicola; Kasuboski, Larry

    2006-11-01

    The magnetization response of hyperpolarized 3He gas to a steady-state free precession (SSFP) sequence was simulated using matrix product operators. The simulations included the effects of flip angle ( α), sequence timings, resonant frequency, gas diffusion coefficient, imaging gradients, T1 and T2. Experiments performed at 1.5 T, on gas phantoms and with healthy human subjects, confirm the predicted theory, and indicate increased SNR with SSFP through use of higher flip angles when compared to optimized spoiled gradient echo (SPGR). Simulations and experiments show some compromise to the SNR and some point spread function broadening at high α due to the incomplete refocusing of transverse magnetization, caused by diffusion dephasing from the readout gradient. Mixing of gas polarization levels by diffusion between slices is also identified as a source of signal loss in SSFP at higher α through incomplete refocusing. Nevertheless, in the sample experiments, a SSFP sequence with an optimized flip angle of α = 20°, and 128 sequential phase encoding views, showed a higher SNR when compared to SPGR ( α = 7.2°) with the same bandwidth. Some of the gas sample experiments demonstrated a transient signal response that deviates from theory in the initial phase. This was identified as being caused by radiation damping interactions between the large initial transverse magnetization and the high quality factor ( Q = 250) birdcage resonator. In 3He NMR experiments, performed without imaging gradients, diffusion dephasing can be mitigated, and the effective T2 is relatively long (⩾1 s). Under these circumstances the SSFP sequence behaves like a CPMG sequence with sin( α/2) weighting of SNR. Experiments and simulations were also performed to characterize the off-resonance behaviour of the SSFP HP 3He signal. Characteristic banding artifacts due to off-resonance harmonic beating were observed in some of the in vivo SSFP images, for instance in axial slices close to the

  19. Steady-state free precession with hyperpolarized 3He: experiments and theory.

    PubMed

    Wild, Jim M; Teh, Kevin; Woodhouse, Neil; Paley, Martyn N J; Fichele, Stan; de Zanche, Nicola; Kasuboski, Larry

    2006-11-01

    The magnetization response of hyperpolarized 3He gas to a steady-state free precession (SSFP) sequence was simulated using matrix product operators. The simulations included the effects of flip angle (alpha), sequence timings, resonant frequency, gas diffusion coefficient, imaging gradients, T1 and T2. Experiments performed at 1.5 T, on gas phantoms and with healthy human subjects, confirm the predicted theory, and indicate increased SNR with SSFP through use of higher flip angles when compared to optimized spoiled gradient echo (SPGR). Simulations and experiments show some compromise to the SNR and some point spread function broadening at high alpha due to the incomplete refocusing of transverse magnetization, caused by diffusion dephasing from the readout gradient. Mixing of gas polarization levels by diffusion between slices is also identified as a source of signal loss in SSFP at higher alpha through incomplete refocusing. Nevertheless, in the sample experiments, a SSFP sequence with an optimized flip angle of alpha=20 degrees, and 128 sequential phase encoding views, showed a higher SNR when compared to SPGR (alpha=7.2 degrees) with the same bandwidth. Some of the gas sample experiments demonstrated a transient signal response that deviates from theory in the initial phase. This was identified as being caused by radiation damping interactions between the large initial transverse magnetization and the high quality factor (Q=250) birdcage resonator. In 3He NMR experiments, performed without imaging gradients, diffusion dephasing can be mitigated, and the effective T2 is relatively long (1 s). Under these circumstances the SSFP sequence behaves like a CPMG sequence with sinalpha/2 weighting of SNR. Experiments and simulations were also performed to characterize the off-resonance behaviour of the SSFP HP 3He signal. Characteristic banding artifacts due to off-resonance harmonic beating were observed in some of the in vivo SSFP images, for instance in axial slices

  20. Peculiar half-metallic state in zigzag nanoribbons of MoS2: Spin filtering

    NASA Astrophysics Data System (ADS)

    Khoeini, F.; Shakouri, Kh.; Peeters, F. M.

    2016-09-01

    Layered structures of molybdenum disulfide (MoS2) belong to a new class of two-dimensional (2D) semiconductor materials in which monolayers exhibit a direct band gap in their electronic spectrum. This band gap has recently been shown to vanish due to the presence of metallic edge modes when MoS2 monolayers are terminated by zigzag edges on both sides. Here, we demonstrate that a zigzag nanoribbon of MoS2, when exposed to an external exchange field in combination with a transverse electric field, has the potential to exhibit a peculiar half-metallic nature and thereby allows electrons of only one spin direction to move. The peculiarity of such spin-selective conductors originates from a spin switch near the gap-closing region, so the allowed spin orientation can be controlled by means of an external gate voltage. It is shown that the induced half-metallic phase is resistant to random fluctuations of the exchange field as well as the presence of edge vacancies.

  1. A study of the 90Zr( 3He, t) reaction at 43.4 MeV

    NASA Astrophysics Data System (ADS)

    Fields, C. A.; Ristinen, R. A.; Samuelson, L. E.; Smith, P. A.

    1982-09-01

    Low-lying states of 90Nb have been investigated using the 90Zr( 3He, t) reaction at 43.4 MeV. In addition to the well-known π( P{1}/{2}) v (g {9}/{2}) -1and π(g {9}/{2}) v (g {9}/{2}) -1 particle-hole states, many other levels were observed. The angular distributions for the ( g{9}/{2}) 2 states are investigated using DWBA calculations using collective, OPEP, and independent tensor and spin-isospin potentials.

  2. Determination of the neutron electric form factor from the reaction 3He(e,e'n) at medium momentum transfer

    NASA Astrophysics Data System (ADS)

    Becker, J.; Andresen, H. G.; Annand, J. R. M.; Aulenbacher, K.; Beuchel, K.; Blume-Werry, J.; Dombo, Th.; Drescher, P.; Ebert, M.; Eyl, D.; Frey, A.; Grabmayr, P.; Großmann, T.; Hartmann, P.; Hehl, T.; Heil, W.; Herberg, C.; Hoffmann, J.; Kellie, J. D.; Klein, F.; Livingston, K.; Leduc, M.; Meyerhoff, M.; Möller, H.; Nachtigall, Ch.; Natter, A.; Ostrick, M.; Otten, E. W.; Owens, R. O.; Plützer, S.; Reichert, E.; Rohe, D.; Schäfer, M.; Schmieden, H.; Sprengard, R.; Steigerwald, M.; Steffens, K.-H.; Surkau, R.; Walcher, Th.; Watson, R.; Wilms, E.

    The electric form factor of the neutron GEn has been determined in double polarized exclusive 3He(e,e'n) scattering in quasi-elastic kinematics by measuring asymmetries A⊥, A∥ of the cross section with respect to helicity reversal of the electron, with the nuclear spin being oriented perpendicular to the momentum transfer q in case of A⊥ and parallel in case of A∥. The experiment was performed at the 855 MeV c. w. microtron MAMI at Mainz. The degree of polarization of the electron beam and of the gaseous 3He target were each about 50%. Scattered electrons and neutrons were detected in coincidence by detector arrays covering large solid angles. Quasi-elastic scattering events were reconstructed from the measured electron scattering angles ϑe, φe and the neutron momentum vector pn' in the plane wave impulse approximation. We obtain the result (0.27 < Q2c2/GeV2 < 0.5)= 0.0334 +/- 0.0033stat+/- 0.0028syst which is averaged over the indicated range of Q2, the squared momentum transfer. This GEn value is significantly smaller than measured from the D(e,e'n) reaction under similar kinematical conditions. To what extent final state interactions in 3He quench the GEn result is subject of calculations currently in progress elsewhere.

  3. 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

  4. Spin filtering and thermopower in star-coupled quantum dot devices

    NASA Astrophysics Data System (ADS)

    Andrade, J. A.; Cornaglia, Pablo S.

    2016-12-01

    We analyze the linear thermoelectric transport properties of devices with three quantum dots in a star configuration. A central quantum dot is tunnel-coupled to source and drain electrodes and to two additional quantum dots. For a wide range of parameters, in the absence of an external magnetic field, the system is a singular Fermi liquid with a nonanalytic behavior of the electric transport properties at low energies. The singular behavior is associated with the development of a ferromagnetic or an underscreened Kondo effect, depending on the parameter regime. A magnetic field drives the system into a regular Fermi liquid regime and leads to a large peak (˜kB/|e | ) in the spin thermopower as a function of the temperature, and to a ˜100 % spin polarized current for a wide range of parameters due to interference effects. We find a qualitatively equivalent behavior for systems with a larger number of side-coupled quantum dots, with the maximum value of the spin thermopower decreasing as the number of side-coupled quantum dots increases.

  5. 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.

  6. A new multiple quantum filter design procedure for use on strongly coupled spin systems found in vivo: its application to glutamate.

    PubMed

    Thompson, R B; Allen, P S

    1998-05-01

    A numerical procedure is outlined that is appropriate for the design of multiple quantum filter sequences targeted for the strongly coupled, multiple spin systems that occur in metabolites present in brain. The procedure uses numerical methods of solution of the density matrix equations, first, to establish the most appropriate resonance to target with the filter; second, to provide contour plots of a performance index of the filter in terms of critical sequence parameters; and third, to produce the response signals of the target and the background metabolites to the optimized filter. The procedure is exemplified for the AMNPQ spin system of the amino acid glutamate at a field strength of 3 T. The 2.3 ppm peak of the PQ multiplet of glutamate was identified as the target resonance, and the performance of the filter so derived was evaluated experimentally on phantom solutions and in human brain. These experiments clearly demonstrate that a linewidth of filter. Nevertheless, even at a linewidth of approximately 7 Hz in vivo, the 2.3 ppm peak of glutamate dominates the filter response and thereby removes a significant cause of uncertainty in measuring changes in glutamate by eliminating most of the background observed in unedited spectra obtained using PRESS or STEAM.

  7. Near threshold two meson production with the pd→3Heπ+π- and pd→3HeK+K- reactions

    NASA Astrophysics Data System (ADS)

    Bellemann, F.; Berg, A.; Bisplinghoff, J.; Bohlscheid, G.; Ernst, J.; Henrich, C.; Hinterberger, F.; Ibald, R.; Jahn, R.; Jarczyk, L.; Joosten, R.; Kozela, A.; Machner, H.; Magiera, A.; Maschuw, R.; Mayer-Kuckuk, T.; Mertler, G.; Munkel, J.; von Neumann-Cosel, P.; Rosendaal, D.; von Rossen, P.; Schnitker, H.; Scho, K.; Smyrski, J.; Strzalkowski, A.; Tölle, R.; Wilkin, C.

    2000-06-01

    Near threshold two meson production via the reactions pd→3Heπ+π- and pd→3HeK+K- was measured kinematically complete with the MOMO experiment at COSY. The obtained two pion invariant mass spectra and angular distributions depict a remarkable deviation from phase space. The two kaon data are consistent with phase space topped by a clear signal of the φ meson.

  8. Thermodynamic properties of liquid 3He- 4He mixtures at zero pressure for temperatures below 250 mK and 3He concentrations below 8%

    NASA Astrophysics Data System (ADS)

    Kuerten, J. G. M.; Castelijns, C. A. M.; de Waele, A. T. A. M.; Gijsman, H. M.

    We calculated the thermodynamic quantities of dilute liquid 3He- 4He mixtures, starting from experimental values of the specific heat and the osmotic pressure. The calculations are confined to temperatures below 250 mK and 3He concentrations below 8% at zero pressure. Some results are especially useful for dilution refrigeration. Contrary to the calculations previously performed by Radebaugh, our results are in good agreement with the experimental date on both the osmotic pressure and the osmotic enthalpy.

  9. 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.

  10. Transport in very dilute solutions of 3He in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Baym, Gordon; Beck, D. H.; Pethick, C. J.

    2013-07-01

    Motivated by a proposed experimental search for the electric dipole moment of the neutron (nEDM) utilizing neutron-3He capture in a dilute solution of 3He in superfluid 4He, we derive the transport properties of dilute solutions in the regime where the 3He are classically distributed and rapid 3He-3He scatterings keep the 3He in equilibrium. Our microscopic framework takes into account phonon-phonon, phonon-3He, and 3He-3He scatterings. We then apply these calculations to measurements by Rosenbaum [J. Low Temp. Phys.JLTPAC0022-229110.1007/BF00655864 16, 131 (1974)] and by Lamoreaux [Europhys. Lett.EULEEJ0295-507510.1209/epl/i2002-00408-4 58, 718 (2002)] of dilute solutions in the presence of a heat flow. We find satisfactory agreement of theory with the data, serving to confirm our understanding of the microscopics of the helium in the future nEDM experiment.

  11. (3)He-MRI in follow-up of lung transplant recipients.

    PubMed

    Gast, Klaus Kurt; Zaporozhan, Julia; Ley, Sebastian; Biedermann, Alexander; Knitz, Frank; Eberle, Balthasar; Schmiedeskamp, Joerg; Heussel, Claus-Peter; Mayer, Eckhard; Schreiber, Wolfgang Günter; Thelen, Manfred; Kauczor, Hans-Ulrich

    2004-01-01

    The aim of this study was to evaluate the possible contribution of (3)He-MRI to detect obliterative bronchiolitis (OB) in the follow-up of lung transplant recipients. Nine single- and double-lung transplanted patients were studied by an initial and a follow-up (3)He-MRI study. Images were evaluated subjectively by estimation of ventilation defect area and quantitatively by individually adapted threshold segmentation and subsequent calculation of ventilated lung volume. Bronchiolitis obliterans syndrome (BOS) was diagnosed using pulmonary function tests. At (3)He-MRI, OB was suspected if ventilated lung volume had decreased by 10% or more at the follow-up MRI study compared with the initial study. General accordance between pulmonary function testing and (3)He-MRI was good, although subjective evaluation of (3)He-MRI underestimated improvement in ventilation as obtained by pulmonary function tests. The (3)He-MRI indicated OB in 6 cases. According to pulmonary function tests, BOS was diagnosed in 5 cases. All diagnoses of BOS were also detected by (3)He-MRI. In 2 of these 5 cases, (3)He-MRI indicated OB earlier than pulmonary function tests. The results support the hypothesis that (3)He-MRI may be sensitive for early detection of OB and emphasize the need for larger prospective follow-up studies.

  12. Cluster folding model analysis of 3He elastic and inelastic scattering from 12C

    NASA Astrophysics Data System (ADS)

    Khallaf, S. A. E.; Nossair, A. M. A.; Ebrahim, A. A.; Ebraheem, Awad A.

    2003-02-01

    Angular distributions of differential cross sections for the 12C( 3He, 3He) 12C, 12C( 3He, 3He) 12C ∗ reactions at E=72 MeV have been analyzed with a double folding cluster model DFC based on five sets of the effective N-N interaction of Gaussian form with different parameters. The transition to the (2 +; 4.44 MeV) state in 12C is studied and the deformation length δ2 is extracted. It is found that the extracted deformation length is sensitive to the nuclear model used and it is similar to the corresponding value found in the literature.

  13. Development of a thermodynamic model for a cold cycle 3He-4He dilution refrigerator

    NASA Astrophysics Data System (ADS)

    Mueller, B. W.; Miller, F. K.

    2016-10-01

    A thermodynamic model of a 3He-4He cold cycle dilution refrigerator with no actively-driven mechanical components is developed and investigated. The refrigerator employs a reversible superfluid magnetic pump, passive check valves, a phase separation chamber, and a series of recuperative heat exchangers to continuously circulate 3He-4He and maintain a 3He concentration gradient across the mixing chamber. The model predicts cooling power and mixing chamber temperature for a range of design and operating parameters, allowing an evaluation of feasibility for potential 3He-4He cold cycle dilution refrigerator prototype designs. Model simulations for a prototype refrigerator design are presented.

  14. Spin-filtered and spatially distinguishable crossed Andreev reflection in a silicene-superconductor junction

    NASA Astrophysics Data System (ADS)

    Li, Kangkang; Zhang, Yan-Yang

    2016-10-01

    We theoretically investigate the quantum transport in a junction between a superconductor and a silicene nanoribbon, under the effect of a magnetic exchange field. We find that for a narrow nanoribbon of silicene, remarkable crossed Andreev reflection (with a fraction >50 % ) can be induced in the energy window of the elastic cotunneling, by destroying some symmetries of the system. Since the energy responses of electrons to the exchange field are opposite for opposite spins, these transport channels can be well spin polarized. Moreover, due to the helicity conservation of the topological edge states, the Andreev reflection, the crossed Andreev reflection, and the elastic cotunneling are spatially separated in three different locations of the device, making them experimentally distinguishable. This crossed Andreev reflection is a nonlocal quantum interference between opposite edges through evanescent modes. If two superconducting leads with different phases are connected to two edges of the silicene nanoribbon, the crossed Andreev reflection can present Josephson type oscillations, with a maximal fraction ˜100 % .

  15. A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF.

    PubMed

    Rinderknecht, H G; Johnson, M Gatu; Zylstra, A B; Sinenian, N; Rosenberg, M J; Frenje, J A; Waugh, C J; Li, C K; Sèguin, 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; Döppner, T; Park, H S; LePape, S; Landen, O; Meezan, N; Moses, E I; Glebov, V U; Stoeckl, C; Sangster, T C; Olson, R; Kline, J; Kilkenny, J

    2012-10-01

    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 ρR 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(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(3)He-filled surrogate implosions using D(3)He protons and DD-neutrons, respectively.

  16. 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.

  17. Type 3 solar radio bursts and 3HE-rich events

    NASA Technical Reports Server (NTRS)

    Reames, D. V.; Stone, R. G.

    1985-01-01

    The kilometric radio data for 3He-rich events during the 1979 to 82 time period were investigated. Type 3 bursts are present for each event as expected from the prevous electron 3He-event association. A list of identified solar events is presented.

  18. Fusion product studies via fast ion D-D and D-3He fusion on JET

    NASA Astrophysics Data System (ADS)

    Sharapov, S. E.; Hellsten, T.; Kiptily, V. G.; Craciunescu, T.; Eriksson, J.; Fitzgerald, M.; Girardo, J.-B.; Goloborod'ko, V.; Hellesen, C.; Hjalmarsson, A.; Johnson, T.; Kazakov, Y.; Koskela, T.; Mantsinen, M.; Monakhov, I.; Nabais, F.; Nocente, M.; Perez von Thun, C.; Rimini, F.; Santala, M.; Schneider, M.; Tardocchi, M.; Tsalas, M.; Yavorskij, V.; Zoita, V.; Contributors, JET

    2016-11-01

    Dedicated fast ion D-D and D-3He fusion experiments were performed on JET with carbon wall (2008) and ITER-like wall (2014) for testing the upgraded neutron and energetic ion diagnostics of fusion products. Energy spectrum of D-D neutrons was the focus of the studies in pure deuterium plasmas. A significant broadening of the energy spectrum of neutrons born in D-D fast fusion was observed, and dependence of the maximum D and D-D neutron energies on plasma density was established. Diagnostics of charged products of aneutronic D-3He fusion reactions, 3.7 MeV alpha-particles similar to those in D-T fusion, and 14.6 MeV protons, were the focus of the studies in D-3He plasmas. Measurements of 16.4 MeV gamma-rays born in the weak secondary branch of D(3He, γ)5Li reaction were used for assessing D-3He fusion power. For achieving high yield of D-D and D-3He reactions at relatively low levels of input heating power, an acceleration of D beam up to the MeV energy range was used employing 3rd harmonic (f=3{{f}CD} ) ICRH technique. These results were compared to the techniques of D beam injection into D-3He mixture, and 3He-minority ICRH in D plasmas.

  19. 4 He adsorption on a 3He-plated graphite surface

    NASA Astrophysics Data System (ADS)

    Kwon, Yongkyung; Ahn, Jeonghwan

    Path-integral Monte Carlo (PIMC) calculations have been performed for 4He atoms on top of the 3He first layer on graphite. For this we ignore Fermi statistics of solidified 3He adatoms while Bose statistics of 4He atoms are fully incorporated. We first find that the first 3He layer exhibits a 7/12 commensurate solid structure at the areal density of 0.111 Å-2, which turns out to be identical to the experimental value for its completion density. Additional adsorption of 4He atoms above the complete first 3He layer is found to sustain the underlying 3He commensurate structure and the second 4He layer is observed to display the 4/7 commensurate structure with respect to the first-layer commensurate 3He solid at the areal density of 0.0636 Å-2. Furthermore, it is found that the 4/7 commensurate structure of the second-layer 4He atoms can be formed above a mixture of the first-layer 3He and 4He atoms on graphite. These PIMC results suggest that the 4/7 commensurate structure of the second-layer 4He atoms on graphite, whose existence on top of the first 4He layer has long been in dispute, may be realized on a 3He-plated graphite surface. This could lead to a new approach to observe two-dimensional supersolidity in 4He on graphite.

  20. Nuclear georeactor origin of oceanic basalt 3He/4He, evidence, and implications.

    PubMed

    Herndon, J Marvin

    2003-03-18

    Nuclear georeactor numerical simulation results yield substantial (3)He and (4)He production and (3)He(4)He ratios relative to air (R(A)) that encompass the entire 2-SD (2sigma) confidence level range of tabulated measured (3)He(4)He ratios of basalts from along the global spreading ridge system. Georeactor-produced (3)He(4)He 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 (3)He(4)He 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.

  1. 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

  2. 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.

  3. Interpretation of the Processes 3He(e,e'p)2H and 3He(e,e'p)(pn) at High Missing Momenta

    NASA Astrophysics Data System (ADS)

    Ciofi Degli Atti, C.; Kaptari, L. P.

    2005-07-01

    Using realistic three-body wave functions corresponding to the AV18 interaction, it is shown that the effects of the final state interaction in the exclusive processes 3He(e,e'p)2H and 3He(e,e'p)(pn), can be successfully treated in terms of a generalized eikonal approximation based upon the direct calculation of the Feynman diagrams describing the rescattering of the struck nucleon. The relevant role played by the double rescattering contribution at high values of the missing momentum is illustrated.

  4. Interpretation of the processes 3He(e,e'p)2H and 3He(e,e'p)(pn) at high missing momenta.

    PubMed

    Ciofi degli Atti, C; Kaptari, L P

    2005-07-29

    Using realistic three-body wave functions corresponding to the AV18 interaction, it is shown that the effects of the final state interaction in the exclusive processes 3He(e,e'p)2H and 3He(e,e'p)(pn), can be successfully treated in terms of a generalized eikonal approximation based upon the direct calculation of the Feynman diagrams describing the rescattering of the struck nucleon. The relevant role played by the double rescattering contribution at high values of the missing momentum is illustrated.

  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. Control of fine particulate emissions from coal-fired utility boilers: Spin filter collection device (rotary cyclone)

    SciTech Connect

    He, Bo X.

    1990-01-01

    A bench-scale test program has been performed to evaluate the concept of placing a porous cylindrical surface (such as a metal screen) at the core of a container and spinning the surface with an external motor for fine particulate/gas separation. The rotating surface enhances the centrifugal effects in the annular region and provides a smooth transition between the flow in the annular and core regions and acts like an enhanced cyclone. It is therefore called a rotary cyclone.'' The porous surface is self-cleaning and offers good steady-state pressure drop characteristics. Objectives of this project are: (1) to carry out theoretical and experimental investigations using the rotary cyclone concept to capture particulates in the 0.5 to 10 micron size range; and (2) to evaluate its economic feasibility based on an engineering scale-up and comparison with conventional fabric filter and electrostatic precipitator systems. It was demonstrated that the efficiency in separating fine particulates is governed by two major characteristics, i.e., the magnitude of the centrifugal force and the approach velocity or the gas-to-surface area ratio. Results from the bench-scale tests have shown a collection efficiency of well over 99% for a typical fly ash. A preliminary conceptual design for a 40 MW installation was developed based on the experimental work. 4 refs., 4 figs., 8 tabs.

  7. 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

  8. 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.

  9. Enhanced IR hollow cathode laser in a 3He Ne gas mixture

    NASA Astrophysics Data System (ADS)

    Stefanova, M. S.; Pramatarov, P. M.; Karelin, A. V.

    2005-09-01

    An experimental and theoretical study on 3He-Ne and 4He-Ne helical hollow cathode lasers is presented. Enhanced laser operation on the near IR NeI lines is observed when the natural isotope 4He is substituted by the lighter isotope 3He. A four-fold increase in the laser output power and a three-fold increase in the laser gain for the strongest NeI 1.1523 µm line is measured in the 3He-Ne gas mixture compared to the 4He-Ne gas mixture. On the basis of the theoretical analysis done by means of a non-stationary kinetic model for the negative glow plasma of 3He-Ne and 4He-Ne hollow cathode lasers, a study on the changes in the particle kinetics is carried out and an explanation of the experimental results is proposed. In the 3He-Ne mixture the electron temperature is lower than in the 4He-Ne mixture, while the gas temperature is higher. As a result the helium triplet metastable density and the rate constant for excitation transfer to neon atoms are higher in the 3He-Ne mixture. The lower laser level de-excitation due to intra-multiplet mixing of 2p1-10levels by 3He atoms is more efficient.

  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. The cosmological density of baryons from observations of 3He+ in the Milky Way.

    PubMed

    Bania, T M; Rood, Robert T; Balser, Dana S

    2002-01-03

    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.

  12. The heavy ion composition in 3HE-rich solar flares

    NASA Technical Reports Server (NTRS)

    Mason, G. M.; Reames, D. V.; Hovestadt, D.; Vonrosenvinge, T. T.

    1985-01-01

    The 3He-rich flares show a tendency to be enriched in heavy ions, and that this enrichment covers the charge range through Fe. The discovery of this association was responsible, in part, for the discarding of 3He enrichment models which involved spallation or thermonuclear reactions, since such models were unable to produce heavy nuclei enhancement. Results of a survey of heavy nucleus abundances observed in 66 3He-rich flares which occurred over the period October 1978 to June 1982 are presented.

  13. 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

  14. 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.

  15. A measurement of the parity violating asymmetry in the neutron capture on 3He at the SNS.

    NASA Astrophysics Data System (ADS)

    Kabir, Latiful; The n-3He Collaboration

    2017-01-01

    Studies of parity violating (PV) observables in hadronic systems offer a unique probe of nucleon structure, complementary to other probes of low-energy non-perturbative QCD. The n-3He experiment at the Spallation Neutron Source at the ORNL measures the PV asymmetry of the recoil proton momentum k-> with respect to the neutron spin σ-> in the reaction n +3 He -> p + T + 764 keV . This asymmetry is sensitive to the isospin-conserving and isospin-changing (ΔI = 0, 1) channels of the Hadronic Weak Interaction, and is expected to be extremely small ( 10-7). The experiment will determine this PV asymmetry with the statistical sensitivity of the order of 10-8. Challenges like beam fluctuation, pedestal and background subtraction, instrumental interference, detector correlations and many others must be considered very carefully in the analysis to achieve this precision. I will discuss the data analysis and a method to extract the value for the PV asymmetry.

  16. Nuclear structure studies of 125Te with (n,γ), (d,p) and ( 3He,α) reactions

    NASA Astrophysics Data System (ADS)

    Honzátko, J.; Tomandl, I.; Bondarenko, V.; Bucurescu, D.; von Egidy, T.; Ott, J.; Schauer, W.; Wirth, H.-F.; Doll, C.; Gollwitzer, A.; Graw, G.; Hertenberger, R.; Valnion, B. D.

    1999-01-01

    Levels in 125Te were investigated in the range up to 3.3 MeV excitation energy by the (n,γ), (d,p) and ( 3He,α) reactions. Over 160 levels and about 360 γ-transitions were established, most for the first time. The states below 2.3 MeV with the most complete spectroscopic information were interpreted in terms of the interacting boson-fermion model (IBFM). Unitary treatment of both positive- and negative-parity states is achieved with the same model parameter close to the intermediate case between O(6) and U(5) limits. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with the possible structures. A family of low-spin negative-parity states has been identified and understood by the IBFM proving their antialigned origin.

  17. The enigmatic high 3He/4He mantle: Characteristics and Origins. (Invited)

    NASA Astrophysics Data System (ADS)

    Jackson, M. G.

    2009-12-01

    Noble gas isotopes measured in some oceanic island basalts (OIBs) exhibit ratios that are associated with the solar wind and the atmosphere of Jupiter, suggesting that the lavas tap portions of an ancient reservoir that still resides in the Earth’s mantle [e.g., 1]. High 3He/4He, as seen in the sources of some OIBs, can therefore serve as a powerful indicator for tracing ancient signatures that have survived in the Earth’s interior. However, the storage mechanisms and reasons for long-term survival of the high 3He/4He signature in the Earth’s convecting mantle are poorly understood. One important observation is that high 3He/4He lavas have 143Nd/144Nd ratios that are higher than chondrites, suggesting that they were derived from a mantle reservoir that suffered ancient depletion. The association of primitive, high 3He/4He with depleted, nonprimitive 143Nd/144Nd in OIBs is not straightforward and a number of models have been developed to resolve this apparent complexity [e.g., 2,3,4,5,6]. It is also becoming apparent that the high 3He/4He reservoir is heterogeneous. High 3He/4He (>30 times atmospheric) lavas from Hawaii, Iceland and Galapagos have more depleted 143Nd/144Nd (0.51294-0.51297) than lavas with similarly high 3He/4He from Samoa (0.51283). In fact, the highest 3He/4He sample from each southern hemisphere high 3He/4He hotspot (FOZO-A, austral) exhibits lower 143Nd/144Nd ratios their northern hemisphere (FOZO-B, boreal) counterparts. The mechanism for this separation is unknown, but it is similar in spatial scale to the DUPAL anomaly, a globe-encircling feature of isotopic enrichment observed primarily in southern hemisphere OIBs. With the exception of Baffin Is. picrites [7], high 3He/4He OIBs also exhibit evidence for Ti, Ta, and Nb (TITAN) enrichment relative to low 3He/4He OIBs. This was interpreted as the result of addition of refractory, rutile-bearing eclogite to a peridotitic high 3He/4He reservoir [8]. This hypothesis is supported by the

  18. 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

  19. Preservation of extraterrestrial 3He in 480-Ma-old marine limestones.

    PubMed

    Patterson, D B; Farley, K A; Schmitz, B

    1998-11-01

    We have measured the helium abundance and isotopic composition of a suite of Lower Ordovician marine limestones and associated fossil meteorites from Kinnekulle, Sweden. Limestone 3He/4He ratios as high as 11.5 times the atmospheric value in fused samples and up to 23 times atmospheric in a single step-heat fraction indicate the presence of extraterrestrial helium, and demonstrate that at least a fraction of the extraterrestrial 3He carried by interplanetary dust particles must be retained against diffusive and diagenetic losses for up to 480 Ma. The carrier phase has not been identified but is not magnetic. Extrapolation of high-temperature 3He diffusivities in these sediments is consistent with strong retention of extraterrestrial 3He under ambient Earth-surface conditions. Combination of the observed helium concentrations with sedimentation rates estimated from conodont biostratigraphy suggest that the flux of extraterrestrial 3He in the Early Ordovician was about 0.5 x 10(-12) cm3 STP cm-2 ka-1, ignoring potential post-deposition helium loss. This value is indistinguishable from the average 3He flux estimated for the Cenozoic Era. In contrast, previous studies of fossil meteorites, Ir abundances, and Os isotopic ratios in the limestone suggest that the total accretion rate of extraterrestrial material during the studied interval was at least an order of magnitude higher than the Cenozoic average. This disparity may reflect significant post-depositional loss of 3He from IDPs within these old limestones; if so, the match between the Ordovician flux and the Cenozoic average would be fortuitous. Alternatively, the size distribution of infalling objects during the Early Ordovician may have been enriched only in extraterrestrial material too large to retain 3He during atmospheric entry heating (> approximately 30 micrometers). The fossil meteorites themselves also preserve extraterrestrial helium. Meteorite 3He concentrations of 2 to 9 x 10(-12) cm3 STP g-1 are

  20. 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.

  1. High-efficiency microstructured semiconductor neutron detectors for direct 3He replacement

    NASA Astrophysics Data System (ADS)

    Fronk, R. G.; Bellinger, S. L.; Henson, L. C.; Huddleston, D. E.; Ochs, T. R.; Sobering, T. J.; McGregor, D. S.

    2015-04-01

    High-efficiency Microstructured Semiconductor Neutron Detectors (MSNDs) have been tiled and arranged in a cylindrical form factor in order to serve as a direct replacement to aging and increasingly expensive 3He gas-filled proportional neutron detectors. Two 6-in long by 2-in diameter cylinders were constructed and populated with MSNDs which were then directly compared to a 4 atm Reuter Stokes 3He detector of the same dimensions. The Generation 1 MSND-based 3Helium-Replacement (HeRep Mk I) device contained sixty-four 1-cm2 active-area MSNDs, each with an intrinsic neutron detection efficiency of approximately 7%. A Generation 2 device (the HeRep Mk II) was populated with thirty 4-cm2 active-area MSNDs, with an intrinsic thermal neutron detection efficiency of approximately 30%. The MSNDs of each HeRep were integrated to count as a single device. The 3He proportional counter and the HeRep devices were tested while encased in a cylinder of high-density polyethylene measuring a total of 6-in by 9-in. The 3He counter and the HeRep Mk II were each placed 1 m from a 54-ng 252Cf source and tested for efficiency. The 3He proportional counter had a net count rate of 17.13±0.10 cps at 1 m. The HeRep Mk II device had a net count rate of 17.60±0.10 cps, amounting to 102.71±2.65% of the 3He gas counter while inside of the moderator. Outside of moderator, the 3He tube had a count rate of 3.35±0.05 cps and the HeRep Mk II device reported 3.19±05, amounting to 95.15±9.04% of the 3He neutron detector.

  2. Meson exchange currents for nuclear muon capture by {sup 3}He

    SciTech Connect

    Congleton, J.G.; Truhlik, E.

    1995-05-10

    We have calculated exchange corrections for nuclear muon capture by {sup 3}He using the hard pion method for the currents and wavefunctions for {sup 3}He and {sup 3}H found by the coupled rearrangement channel method. The result for the rate (triton asymmetry) has an uncertainty of 3% (1%) due mainly to the uncertainty in the value of {ital f}{sub {pi}{ital N}{Delta}} (various factors). {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  3. SANS study of phase separation in solid {sup 3}He-{sup 4}He

    SciTech Connect

    Koster, J.P.; Nagler, S.E.; Adams, E.D.; Wignall, G.D.

    1994-12-31

    Small angle neutron scattering has been used to study phase separation in a quantum alloy, solid {sup 3}He{sub x}-{sup 4}He{sub 1{minus}x}. The onset of phase separation is marked by a dramatic increase in the measured scattering. A simple interpretation of the results suggests that the late-stage phase separation kinetics are dominated by an increase in the concentration of {sup 3}He atoms in preexisting precipitate regions.

  4. 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.

  5. Primordial 3He in South Atlantic deep waters from sources on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Rüth, Christine; Well, Roland; Roether, Wolfgang

    2000-06-01

    Helium isotope data from three zonal WOCE sections (11°S, 19°S and 30°S) in the South Atlantic are presented. Among other features we find a distinct δ 3He-maximum above the Mid-Atlantic Ridge (MAR) at all three latitudes. Using a hydrographic multiparameter analysis, we separate 3He emanating from the MAR from the large-scale 3He background. To our knowledge, this is the first confirmation of input of primordial 3He at the MAR in the South Atlantic. The source appears to be weak compared with the Pacific sources, causing 3He elevations (relative to background values) of only 2-3% directly above the MAR. This exceeds by several times the statistical and systematic data uncertainties, which amount to 0.35% each, so that detailed contouring of the MAR-derived 3He is possible. At 30°S and 11°S, a significant signal extends westward over at least 2000 km, whereas at 19°S the signal is more confined to the ridge area. The westward extensions indicate westward flow at depths near the ridge crest elevation, contradicting flow directions deduced previously by Reid (1989).

  6. An Update on 3He Correlation Function Research for the SNS nEDM collaboration

    NASA Astrophysics Data System (ADS)

    Reid, Austin; Golub, Robert; Dipert, Robert

    2016-09-01

    In the 65 years since Ramsey's null result for the neutron's permanent electric dipole moment (nEDM), techniques have become increasingly sensitive, establishing the present upper limit of 3 ×10-26 e .cm . This value was limited by an unexpected source of error: a freqency shift with linear dependence on the electric field colloquially called a false EDM. The next generation nEDM sensing apparatus being developed for the Spallation Neutron Source at Oak Ridge National Laboratory uses a 3He comagenetometer in a pure helium-II bath. The false EDM in 3He may be related to the 3He's position autocorrelation function, which in turn is accessible by a detailed study of T1 decay in hyperpolarized 3He. Existing measurements of this system were limited by temperature, noise, and 3He concentration. Dramatic improvements have been made on all three fronts by improving the thermal connection between the measurment cell and the dilution refrigerator, by adding additional shielding and a SQUID package, and by developing a MEOP 3He polarization system. Data collection is underway. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award Number DE-FG02-97ER41042.

  7. 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.

  8. 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

  9. An important source of 4He (and 3He) in diamonds

    NASA Astrophysics Data System (ADS)

    Lal, D.

    1989-12-01

    A large data base has recently accumulated on the concentrations of helium isotopes in diamonds mined from various regions. It was noted earlier (Ozima et al. (1985) [1]; Lal et al. (1989) [2]) that the frequency distribution of the 4He concentrations is a fairly narrow one, whereas that of 3He concentrations is a broad one with no pronounced peaks. The ratios 3He/ 4He , on the other hand show a broad maximum around 2 R a ( R a equals atmospheric 3He/ 4He ratio, = 1.40 × 10 -6) with a slow decrease over two orders of magnitude on either side. Does this imply that the diamonds sample a wide variety of helium reservoirs having a range of 3He/ 4He ratios but somehow attain similar 4He concentrations? We propose that in a majority of the diamonds studied, 4He is primarily due to implantation of radiogenic alpha particles from the host material after emplacement in the crust, usually kimberlite, and that the concentrations of 4He in diamonds often get appreciably altered by this process. Thus the 4He trapped in the diamond at the time of its crystallization is usually overwhelmed by the implanted helium and the measured 3He/ 4He ratios do not generally correspond to any "sources" in the mantle. However, the implanted 4He resides in the outer 16 μm of the diamond, and the intrinsic 4He and 3He/ 4He ratios in the diamond can be studied if its outer layers are removed. The wider implications of diamond being the "target" material for nuclear reaction products from the host material are discussed. Radiogenic 3He produced in the host material is also implanted in the diamond, but this contribution is small on a gross basis. However, since the depth of implantation of 3He is greater than that of 4He, some of the very high 3He/ 4He ratios observed in diamonds could be due to the "implantation" of radiogenic 3He. The radiogenic reactions in the host material can also contribute to appreciable 21Ne in diamonds.

  10. Minority and mode conversion heating in (3He)-H JET plasmas

    NASA Astrophysics Data System (ADS)

    Van Eester, D.; Lerche, E.; Johnson, T. J.; Hellsten, T.; Ongena, J.; Mayoral, M.-L.; Frigione, D.; Sozzi, C.; Calabro, G.; Lennholm, M.; Beaumont, P.; Blackman, T.; Brennan, D.; Brett, A.; Cecconello, M.; Coffey, I.; Coyne, A.; Crombe, K.; Czarnecka, A.; Felton, R.; Gatu Johnson, M.; Giroud, C.; Gorini, G.; Hellesen, C.; Jacquet, P.; Kazakov, Ye; Kiptily, V.; Knipe, S.; Krasilnikov, A.; Lin, Y.; Maslov, M.; Monakhov, I.; Noble, C.; Nocente, M.; Pangioni, L.; Proverbio, I.; Stamp, M.; Studholme, W.; Tardocchi, M.; Versloot, T. W.; Vdovin, V.; Whitehurst, A.; Wooldridge, E.; Zoita, V.; EFDA Contributors, JET

    2012-07-01

    Radio frequency (RF) heating experiments have recently been conducted in JET (3He)-H plasmas. This type of plasmas will be used in ITER's non-activated operation phase. Whereas a companion paper in this same PPCF issue will discuss the RF heating scenario's at half the nominal magnetic field, this paper documents the heating performance in (3He)-H plasmas at full field, with fundamental cyclotron heating of 3He as the only possible ion heating scheme in view of the foreseen ITER antenna frequency bandwidth. Dominant electron heating with global heating efficiencies between 30% and 70% depending on the 3He concentration were observed and mode conversion (MC) heating proved to be as efficient as 3He minority heating. The unwanted presence of both 4He and D in the discharges gave rise to 2 MC layers rather than a single one. This together with the fact that the location of the high-field side fast wave (FW) cutoff is a sensitive function of the parallel wave number and that one of the locations of the wave confluences critically depends on the 3He concentration made the interpretation of the results, although more complex, very interesting: three regimes could be distinguished as a function of X[3He]: (i) a regime at low concentration (X[3He] < 1.8%) at which ion cyclotron resonance frequency (ICRF) heating is efficient, (ii) a regime at intermediate concentrations (1.8 < X[3He] < 5%) in which the RF performance is degrading and ultimately becoming very poor, and finally (iii) a good heating regime at 3He concentrations beyond 6%. In this latter regime, the heating efficiency did not critically depend on the actual concentration while at lower concentrations (X[3He] < 4%) a bigger excursion in heating efficiency is observed and the estimates differ somewhat from shot to shot, also depending on whether local or global signals are chosen for the analysis. The different dynamics at the various concentrations can be traced back to the presence of 2 MC layers and their

  11. 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.

  12. Association of 3He-Rich Solar Energetic Particles with Large-scale Coronal Waves

    NASA Astrophysics Data System (ADS)

    Bučík, Radoslav; Innes, Davina E.; Mason, Glenn M.; Wiedenbeck, Mark E.

    2016-12-01

    Small, 3He-rich solar energetic particle (SEP) events have been commonly associated with extreme-ultraviolet (EUV) jets and narrow coronal mass ejections (CMEs) that are believed to be the signatures of magnetic reconnection, involving field lines open to interplanetary space. The elemental and isotopic fractionation in these events are thought to be caused by processes confined to the flare sites. In this study, we identify 32 3He-rich SEP events observed by the Advanced Composition Explorer, near the Earth, during the solar minimum period 2007-2010, and we examine their solar sources with the high resolution Solar Terrestrial Relations Observatory (STEREO) EUV images. Leading the Earth, STEREO-A has provided, for the first time, a direct view on 3He-rich flares, which are generally located on the Sun’s western hemisphere. Surprisingly, we find that about half of the 3He-rich SEP events in this survey are associated with large-scale EUV coronal waves. An examination of the wave front propagation, the source-flare distribution, and the coronal magnetic field connections suggests that the EUV waves may affect the injection of 3He-rich SEPs into interplanetary space.

  13. p +d →3He+γ reaction with pionless effective field theory

    NASA Astrophysics Data System (ADS)

    Nematollahi, H.; Bayegan, S.; Mahboubi, N.; Arani, M. Moeini

    2016-11-01

    We study the proton radiative capture by a deuteron with the pionless effective field theory [EFT(π / )] formalism. The calculation of the p d →3Heγ amplitude is considered for the incoming doublet and quartet channels leading to the formation of a 3He. The strong and Coulomb scattering amplitudes for the proton-deuteron (p d ) scattering are included in this study. In this calculation, the properly normalized 3He wave function has been used at each order. We evaluate both M 1 and E 1 transitions in the p d →3Heγ process up to NLO. We calculate the total cross section for the p d →3Heγ process based on the cluster-configuration space and compare it with the experimental data. The cross section results are presented for the incoming proton with the energy 0.5 ≤E ≤3 MeV where the lower and upper limits are chosen for the treatment of Coulomb effects perturbatively and the EFT(π / ) breakdown scale, respectively. No three-body force is needed to renormalize observables up to NLO other than those we have introduced in the p d scattering amplitudes.

  14. OBSERVATIONS OF EUV WAVES IN {sup 3}He-RICH SOLAR ENERGETIC PARTICLE EVENTS

    SciTech Connect

    Bucík, R.; Innes, D. E.; Guo, L.; Mason, G. M.; Wiedenbeck, M. E.

    2015-10-10

    Small {sup 3}He-rich solar energetic particle (SEP) events with their anomalous abundances, markedly different from the solar system, provide evidence for a unique acceleration mechanism that operates routinely near solar active regions. Although the events are sometimes accompanied by coronal mass ejections (CMEs), it is believed that mass and isotopic fractionation is produced directly in the flare sites on the Sun. We report on a large-scale extreme-ultraviolet (EUV) coronal wave observed in association with {sup 3}He-rich SEP events. In the two examples discussed, the observed waves were triggered by minor flares and appeared concurrently with EUV jets and type III radio bursts, but without CMEs. The energy spectra from one event are consistent with so-called class-1 (characterized by power laws) {sup 3}He-rich SEP events, while the other with class-2 (characterized by rounded {sup 3}He and Fe spectra), suggesting different acceleration mechanisms in the two. The observation of EUV waves suggests that large-scale disturbances, in addition to more commonly associated jets, may be responsible for the production of {sup 3}He-rich SEP events.

  15. 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.

  16. 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.

  17. Phase separation in dilute solutions of 3He in solid 4He

    NASA Astrophysics Data System (ADS)

    Huan, C.; Yin, L.; Xia, J. S.; Candela, D.; Cowan, B. P.; Sullivan, N. S.

    2017-03-01

    We report the results of studies of the phase separation of solid solutions of dilute concentrations of 3He in 4He. The temperatures and the kinetics of the phase separation were determined from NMR experiments for 3He concentrations 1.6 ×10-53He droplets shows a t1 /3 time dependence at long times consistent with Ostwald ripening.

  18. Rotational spectrum of the NH3-He van der Waals complex

    NASA Astrophysics Data System (ADS)

    Surin, L.; Schnell, M.

    2016-12-01

    The interaction between ammonia and helium has attracted considerable interest over many years, partly because of the observation of interstellar ammonia. The rate coefficients of NH3-He scattering are an important ingredient for numerical modeling of astrochemical environments. Another, though quite different application in which the NH3-He interaction can play an important role is the doping of helium clusters with NH3 molecules to perform high-resolution spectroscopy. Such experiments are directed on the detection of non-classical response of molecular rotation in helium clusters addressing fundamental questions related to the microscopic nature of superfluidity. High-resolution spectroscopy on the NH3-He complex is an important tool for increasing our understanding of intermolecular forces between NH3 and He.

  19. 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.

  20. Implications of new High 3He/4He Values from the Samoan Hotspot

    NASA Astrophysics Data System (ADS)

    Jackson, M. G.; Kurz, M. D.; Hart, S. R.; Workman, R.

    2005-12-01

    We report new olivine phenocryst helium measurements from Ofu Island, American Samoa; the 3He/4He ratios range from 19.5 to 33.7 times atmospheric (R/Ra), significantly expanding the observed range for Samoa. The highest 3He/4He ratio of 33.7 Ra was measured in olivines from an ankaramite dike. Relatively high helium concentrations (4.4*108 cc/g) in this sample, crushing and fusion measurements, coupled with sampling from a roadcut exposure, all ensure that the isotope ratio is not affected by in situ cosmogenic 3He. A second basaltic dike yielded a 3He/4He ratio of 29.6 Ra, and measurements on 9 other basalt samples from Ofu range from 19.5 to 26.4 Ra. Previous high 3He/4He measurements (~25 Ra) from the Samoan hotspot were also obtained from basaltic dikes, but were from Tutuila Island (Farley et al., 1992). The new high 3He/4He ratios from Samoa are similar in magnitude to the high ratios found at Iceland (~37 Ra) and Hawaii (~35 Ra). However, the Ofu basalts have 87Sr/86Sr > 0.7044, which is significantly more radiogenic than Iceland or Hawaii. The combined Sr-He isotopic data are broadly consistent with mixing between an enriched mantle source (EM2) and the putative common high 3He/4He component (FOZO, as best represented by Baffin Island Picrites, Stuart et al., 2003). Assuming that the overall isotopic variations are produced by mixing processes, we attempt to place constraints on the relative helium concentrations in the FOZO, EM2 and Depleted MORB mantle (DMM) endmembers. In addition to using the shape of the plausible mixing lines, we employ new estimates for the trace element concentrations in the DMM and Samoan EM2 sources (Workman et al., 2004; Workman and Hart, 2005) to get at relative helium concentrations in these reservoirs. We assume that high 3He/4He basalts from the mid-Atlantic ridge North of Iceland (Schilling et al., 1999, and others) are a mixture between DMM and FOZO. We further assume that the N. Iceland ridge-FOZO and Ofu-FOZO mixing

  1. Chiral effective field theory predictions for muon capture on deuteron and {3}He.

    PubMed

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

    2012-02-03

    The muon-capture reactions {2}H(μ{-},ν{μ})nn and {3}He(μ{-},ν{μ}){3}H are studied with nuclear potentials and charge-changing weak currents, derived in chiral effective field theory. The low-energy constants (LECs) c{D} and c{E}, present in the three-nucleon potential and (c{D}) axial-vector current, are constrained to reproduce the A=3 binding energies and the triton Gamow-Teller matrix element. The muon-capture rates on deuteron and {3}He are predicted to be 399±3  sec{-1} and 1494±21  sec{-1}, respectively. The spread accounts for the cutoff sensitivity, as well as uncertainties in the LECs and electroweak radiative corrections. By comparing the calculated and precisely measured rates on {3}He, a value for the induced pseudoscalar form factor is obtained in good agreement with the chiral perturbation theory prediction.

  2. Observation of a new superfluid phase for 3He embedded in nematically ordered aerogel

    NASA Astrophysics Data System (ADS)

    Zhelev, N.; Reichl, M.; Abhilash, T. S.; Smith, E. N.; Nguyen, K. X.; Mueller, E. J.; Parpia, J. M.

    2016-09-01

    In bulk superfluid 3He at zero magnetic field, two phases emerge with the B-phase stable everywhere except at high pressures and temperatures, where the A-phase is favoured. Aerogels with nanostructure smaller than the superfluid coherence length are the only means to introduce disorder into the superfluid. Here we use a torsion pendulum to study 3He confined in an extremely anisotropic, nematically ordered aerogel consisting of ~10 nm-thick alumina strands, spaced by ~100 nm, and aligned parallel to the pendulum axis. Kinks in the development of the superfluid fraction (at various pressures) as the temperature is varied correspond to phase transitions. Two such transitions are seen in the superfluid state, and we identify the superfluid phase closest to Tc at low pressure as the polar state, a phase that is not seen in bulk 3He.

  3. 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.

  4. Developing a long duration 3He fridge for the LSPE-SWIPE instrument

    NASA Astrophysics Data System (ADS)

    Coppi, Gabriele; de Bernardis, Paolo; May, Andrew J.; Masi, Silvia; McCulloch, Mark; Melhuish, Simon J.; Piccirillo, Lucio

    2016-07-01

    A 3He sorption cooler design for the Short-Wavelength Instrument for the Polarization Explorer (SWIPE) of the Large-Scale Polarization Explorer (LSPE) balloon-borne experiment is described. The aim of this experiment is the detection of the primordial B-mode polarisation component of the Cosmic Microwave Background. The SWIPE instrument will use Transition-Edge Sensors that are designed to work at temperature of almost 300 mK. Therefore, a 3He sorption cooler has been specifically designed that can reach this temperature with a heat load of up to 25 μW. The fridge is compact in order to be housed inside the SWIPE cryostat and operate vertically. It has been designed to have a cycle duration of at least 7 days. In order to meet these specifications, the fridge will be charged with 0.75 moles of 3He.

  5. Observation of a new superfluid phase for 3He embedded in nematically ordered aerogel

    PubMed Central

    Zhelev, N.; Reichl, M.; Abhilash, T. S.; Smith, E. N.; Nguyen, K. X.; Mueller, E. J.; Parpia, J. M.

    2016-01-01

    In bulk superfluid 3He at zero magnetic field, two phases emerge with the B-phase stable everywhere except at high pressures and temperatures, where the A-phase is favoured. Aerogels with nanostructure smaller than the superfluid coherence length are the only means to introduce disorder into the superfluid. Here we use a torsion pendulum to study 3He confined in an extremely anisotropic, nematically ordered aerogel consisting of ∼10 nm-thick alumina strands, spaced by ∼100 nm, and aligned parallel to the pendulum axis. Kinks in the development of the superfluid fraction (at various pressures) as the temperature is varied correspond to phase transitions. Two such transitions are seen in the superfluid state, and we identify the superfluid phase closest to Tc at low pressure as the polar state, a phase that is not seen in bulk 3He. PMID:27669660

  6. 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.

  7. 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.

  8. Two-photon exchange correction to 2 S -2 P splitting in muonic 3He ions

    NASA Astrophysics Data System (ADS)

    Carlson, Carl E.; Gorchtein, Mikhail; Vanderhaeghen, Marc

    2017-01-01

    We calculate the two-photon exchange correction to the Lamb shift in muonic 3He ions within the dispersion relations framework. Part of the effort entailed making analytic fits to the electron-3He quasielastic scattering data set, for purposes of doing the dispersion integrals. Our result is that the energy of the 2 S state is shifted downwards by two-photon exchange effects by 15.14(49) meV, in good accord with the result obtained from a potential model and effective field theory calculation.

  9. 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.

  10. 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.

  11. Observation of Half-Quantum Vortices in Topological Superfluid 3He

    NASA Astrophysics Data System (ADS)

    Autti, S.; Dmitriev, V. V.; Mäkinen, J. T.; Soldatov, A. A.; Volovik, G. E.; Yudin, A. N.; Zavjalov, V. V.; Eltsov, V. B.

    2016-12-01

    One of the most sought-after objects in topological quantum-matter systems is a vortex carrying half a quantum of circulation. They were originally predicted to exist in superfluid 3He -A but have never been resolved there. Here we report an observation of half-quantum vortices (HQVs) in the polar phase of superfluid 3He. The vortices are created with rotation or by the Kibble-Zurek mechanism and identified based on their nuclear magnetic resonance signature. This discovery provides a pathway for studies of unpaired Majorana modes bound to the HQV cores in the polar-distorted A phase.

  12. 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.

  13. Pion single charge exchange scattering from 3He at 285, 428, and 525 MeV

    NASA Astrophysics Data System (ADS)

    Källne, J.; Altemus, R.; Gugelot, P. C.; McCarthy, J. S.; Minehart, R. C.; Orphanos, L.; Gram, P. A. M.; Höistad, B.; Morris, C. L.; Wadlinger, E. A.; Perdrisat, C. F.

    1982-02-01

    We have measured the cross section of 3He(π-,π0)3H at T=285, 428, and 525 MeV for angles in the range of 60°<~θ<~135° covering the momentum transfer range 0.5<~q<~1.0 GeV/c. Comparison is made with Glauber model calculations to discuss the sensitivity to nuclear structure and pion-nucleus interaction effects. NUCLEAR REACTIONS π-+3He-->3H+π0, T=285, 428, and 525 MeV, θπ0~70-140° measured σ(θt,Tπ). Analysis based on optical and Glauber model predictions.

  14. Observation of Half-Quantum Vortices in Topological Superfluid ^{3}He.

    PubMed

    Autti, S; Dmitriev, V V; Mäkinen, J T; Soldatov, A A; Volovik, G E; Yudin, A N; Zavjalov, V V; Eltsov, V B

    2016-12-16

    One of the most sought-after objects in topological quantum-matter systems is a vortex carrying half a quantum of circulation. They were originally predicted to exist in superfluid ^{3}He-A but have never been resolved there. Here we report an observation of half-quantum vortices (HQVs) in the polar phase of superfluid ^{3}He. The vortices are created with rotation or by the Kibble-Zurek mechanism and identified based on their nuclear magnetic resonance signature. This discovery provides a pathway for studies of unpaired Majorana modes bound to the HQV cores in the polar-distorted A phase.

  15. MeV ion loss during sup 3 He minority heating in TFTR

    SciTech Connect

    Zweben, S.J.; Hammett, G.; Boivin, R.; Phillips, C.; Wilson, R.

    1992-01-01

    The loss of MeV ions during {sup 3}He ICRH minority heating experiments has been measured using scintillator detectors near the wall of TFTR. The observed MeV ion losses to the bottom (90{degrees} poloidal) detector are generally consistent with the expected first-orbit loss of D-{sup 3}He alpha particle fusion products, with an inferred global reaction rate up to {approx}10{sup 16} reactions/sec. A qualitatively similar but unexpectedly large loss occurs 45{degrees} poloidally below the outer midplane. This additional loss might be due to ICRH tail ions or to ICRH wave-induced loss of previously confined fusion products.

  16. MeV ion loss during {sup 3}He minority heating in TFTR

    SciTech Connect

    Zweben, S.J.; Hammett, G.; Boivin, R.; Phillips, C.; Wilson, R.

    1992-01-01

    The loss of MeV ions during {sup 3}He ICRH minority heating experiments has been measured using scintillator detectors near the wall of TFTR. The observed MeV ion losses to the bottom (90{degrees} poloidal) detector are generally consistent with the expected first-orbit loss of D-{sup 3}He alpha particle fusion products, with an inferred global reaction rate up to {approx}10{sup 16} reactions/sec. A qualitatively similar but unexpectedly large loss occurs 45{degrees} poloidally below the outer midplane. This additional loss might be due to ICRH tail ions or to ICRH wave-induced loss of previously confined fusion products.

  17. Relativistic, QED, and nuclear mass effects in the magnetic shielding of 3He.

    PubMed

    Rudziński, Adam; Puchalski, Mariusz; Pachucki, Krzysztof

    2009-06-28

    The magnetic shielding sigma of (3)He is studied. The complete relativistic corrections of order O(alpha(2)), leading QED corrections of order O(alpha(3) ln alpha), and finite nuclear mass effects of order O(m/m(N)) are calculated with high numerical precision. The resulting theoretical predictions for sigma = 59.967 43(10)x10(-6) are the most accurate to date among all elements and support the use of (3)He as a NMR standard.

  18. Heat Transfer in 3He -4He Mixtures in Cylindrical Geometry

    NASA Astrophysics Data System (ADS)

    Nemchenko, K.; Rogova, S.; Vikhtinskaya, T.

    2017-02-01

    The paper presents the results of theoretical studies of the transport processes that take place in the newly proposed experiments on study of a vibrating quartz fork in superfluid 3He -4He mixtures. In addition to known mechanisms of energy loss from a vibrating quartz fork such as first sound radiation or interaction with thermal excitations, two more mechanisms specific for 3He -4He mixtures are proposed and studied in the paper. The relative contribution of these mechanisms: second sound and effective diffusion, is considered, and experimental conditions under which these mechanisms become effective are discussed.

  19. 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.

  20. Degassing of 3H/3He, CFCs and SF6 by denitrification: measurements and two-phase transport simulations.

    PubMed

    Visser, Ate; Schaap, Joris D; Broers, Hans Peter; Bierkens, Marc F P

    2009-01-26

    The production of N2 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 SF6 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 sigma) 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 SF6 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.

  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. Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis.

    PubMed

    Eggleton, Peter P; Dearborn, David S P; Lattanzio, John C

    2006-12-08

    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.

  3. 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).

  4. Beam suppression of the DRAGON recoil separator for 3He(α,γ)7Be

    NASA Astrophysics Data System (ADS)

    Sjue, S. K. L.; Nara Singh, B. S.; Adsley, P.; Buchmann, L.; Carmona-Gallardo, M.; Davids, B.; Fallis, J.; Fulton, B. R.; Galinski, N.; Hager, U.; Hass, M.; Howell, D.; Hutcheon, D. A.; Laird, A. M.; Martin, L.; Ottewell, D.; Reeve, S.; Ruiz, C.; Ruprecht, G.; Triambak, S.

    2013-02-01

    Preliminary studies in preparation for an absolute cross-section measurement of the radiative capture reaction 3He(α,γ)7Be with the DRAGON recoil separator have demonstrated beam suppression >1014 at the 90% confidence level. A measurement of this cross section by observation of 7Be recoils at the focal plane of the separator should be virtually background free.

  5. Precise /sup 3/H-/sup 3/He mass difference for neutrino mass determination

    SciTech Connect

    Lippmaa, E.; Pikver, R.; Suurmaa, E.; Past, J.; Puskar, J.; Koppel, I.; Tammik, A.

    1985-01-28

    The precise /sup 3/H-/sup 3/He atomic mass difference has been measured by high-resolution (10/sup -8/) ion cyclotron resonance in a 4.7-T magnetic field. The result of 18 599 +- 2 eV favors a nonzero electron antineutrino mass.

  6. First viscosity of dilute3He-4He mixtures below 0.6 K

    NASA Astrophysics Data System (ADS)

    Um, Chung-In; Yoo, Sahng-Kyoon; Lee, Soo-Young; George, Thomas F.; Pandey, Lakshmi N.

    1994-01-01

    Starting with the Boltzmann transport equation, the first viscosity of dilute3He-4He mixtures for various3He concentrations x is evaluated up to around T ≅ 0.6 K by including the contribution from three-phonon processes (3PP) in the anomalous elementary excitation spectrum of liquid4He. Due to 3PP, the characteristic time τη for3He viscosity at high temperatures, i.e., T⩾2TF where TF is the3He Fermi temperature, is evaluated as 5 × 10-12/xT, which is smaller than the value estimated by Rosenbaum et al. This is interpolated with τη in the degenerate (quantum) region, T≪TF. The obtained viscosities are in better agreement with experimental results than those of Baym and Saam, whose theory does not include 3PP. However, at very low concentrations there exists a discrepancy between the present theory and experiments, so that an alternate treatment should be considered.

  7. Deep Mixing of 3He: Reconciling Big Bang and Stellar Nucleosynthesis

    SciTech Connect

    Eggleton, P P; Dearborn, D P; Lattanzio, J

    2006-07-26

    Low-mass stars, {approx} 1-2 solar masses, near the Main Sequence are efficient at producing {sup 3}He, 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 {sup 3}He with the predictions of both stellar and Big Bang nucleosynthesis. In this paper 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 {sup 3}He production in low-mass stars poses to the Big Bang nucleosynthesis of {sup 3}He.

  8. Testing on novel neutron detectors as alternative to 3He for security applications

    NASA Astrophysics Data System (ADS)

    Peerani, Paolo; Tomanin, Alice; Pozzi, Sara; Dolan, Jennifer; Miller, Eric; Flaska, Marek; Battaglieri, Marco; De Vita, Raffaella; Ficini, Luisa; Ottonello, Giacomo; Ricco, Giovanni; Dermody, Geraint; Giles, Calvin

    2012-12-01

    Detection of illicit trafficking of nuclear material relies on the detection of the radiation emitted. In the case of plutonium, one of the characteristic signatures derives from neutron emission. For this reason, neutron detectors cover an important role in detection systems. Most current neutron detection systems used for nuclear security are based on the 3He technology. Unfortunately, in the last few years the market of 3He has encountered huge problems in matching the supply and the demand. The need has grown significantly due to the increasing demand of instrumentation for security. This has caused an exponential increase of the price from one side and on the other side a serious strategic problem of resources. In order to guarantee the availability of detection systems for nuclear security, it is necessary to develop alternative detection systems based on technologies different from 3He. Many research projects have been devoted for the development of novel neutron detectors both by research organisations and by industries. Scientists from the PERLA laboratory of the Joint Research Centre (JRC) in Ispra, Italy, and their collaborators have tested several of these novel concepts in the last couple of years. This paper describes the detector systems tested at JRC and preliminary results on detectors that can be considered as promising alternatives to 3He.

  9. Effect of 3He on the extinction of mass flux in solid helium

    NASA Astrophysics Data System (ADS)

    Vekhov, Ye.; Hallock, Robet

    2014-03-01

    The flux, F, carried by solid 4He , with nominal 300 ppb 3He concentration, χ, in the range 25.6 - 26.3 bar rises with falling temperature and at a temperature Td the flux decreases toward zero. The behavior of the flux above Td demonstrates the presence of a bosonic Luttinger liquid. We study F as a function of 3He concentration χ to explore the effect of 3He on Td. We find that the extinction of the flux is a sharp transition, typically complete within a few mK change in temperature. We find that Td is an increasing function of χ and we compare (Td , χ) with predictions for homogeneous phase separation. We conclude that phase separation plays an important role in the flux extinction. It is possible that the cores of edge dislocations carry the flux, and the flux is extinguished by the decoration by 3He of the cores or dislocation intersections. Supported by NSF DMR 12-05217.

  10. 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.

  11. Electron Bubbles in Superfluid ^3 He-A: Exploring the Quasiparticle-Ion Interaction

    NASA Astrophysics Data System (ADS)

    Shevtsov, Oleksii; Sauls, J. A.

    2016-11-01

    When an electron is forced into liquid ^3 He, it forms an "electron bubble", a heavy ion with radius, R˜eq 1.5 nm, and mass, M˜eq 100 m_3 , where m_3 is the mass of a ^3 He atom. These negative ions have proven to be powerful local probes of the physical properties of the host quantum fluid, especially the excitation spectra of the superfluid phases. We recently developed a theory for Bogoliubov quasiparticles scattering off electron bubbles embedded in a chiral superfluid that provides a detailed understanding of the spectrum of Weyl Fermions bound to the negative ion, as well as a theory for the forces on moving electron bubbles in superfluid ^3 He-A (Shevtsov and Sauls in Phys Rev B 94:064511, 2016). This theory is shown to provide quantitative agreement with measurements reported by the RIKEN group (Ikegami et al. in Science 341(6141):59, 2013) for the drag force and anomalous Hall effect of moving electron bubbles in superfluid ^3 He-A. In this report, we discuss the sensitivity of the forces on the moving ion to the effective interaction between normal-state quasiparticles and the ion. We consider models for the quasiparticle-ion (QP-ion) interaction, including the hard-sphere potential, constrained random-phase-shifts, and interactions with short-range repulsion and intermediate-range attraction. Our results show that the transverse force responsible for the anomalous Hall effect is particularly sensitive to the structure of the QP-ion potential and that strong short-range repulsion, captured by the hard-sphere potential, provides an accurate model for computing the forces acting on the moving electron bubble in superfluid 3 He-A.

  12. Comparison between impulsive 3He-rich events and energetic electron events

    NASA Astrophysics Data System (ADS)

    Wang, L.; Lin, R. P.; Krucker, S.; Mason, G. M.

    2005-05-01

    Impulsive solar energetic particle (SEP) events with large enrichments of 3He are associated with ~2-100 keV impulsive electrons. Electron observations with the energy range of ~3 eV - 500 keV by the WIND 3-D Plasma and Energetic Particle experiment (3DP) and ion measurements with the energy range of ~ 0.02 - 10 MeV/nucleon by the ACE Ultra-Low Energy Isotopic Spectrometer (ULEIS) provide the first possibility of an accurate timing comparison of between impulsive 3He-rich events and energetic electron events. We select eleven solar impulsive events with enhanced 3He/4He ratios (~0.1 - 1.5) and a clear velocity dispersion of both ion and electron events over a wide energy range. We remove the contaminations of higher energy electrons in Solid State Telescopes (SST) on WIND, determine the interplanetary path length from peak times of WIND electron data observed in situ, and obtain the electron injection profiles at the Sun from triangular fits to in situ observations. The onsets and peaks of the injection of 3He-rich ion events at the Sun are derived from those of ACE ion data observed in situ by taking into account the travel time along the path length comparable to electron events. The comparison study shows a systematic delay of the injection of 3He-rich ions events with respect to the injection of electron events. Nine of ten events have a fast (> 570 km/s) west CME observed by SOHO/LASCO with the onset of electron injection close to the origin of the CME, and with the onset of ion injection corresponding to a median height ~ 5 Rs of CME.

  13. 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.

  14. Reducing Contrast Contamination in Radial Turbo-Spin-Echo Acquisitions by Combining a Narrow-Band KWIC Filter With Parallel Imaging

    PubMed Central

    Neumann, Daniel; Breuer, Felix A.; Völker, Michael; Brandt, Tobias; Griswold, Mark A.; Jakob, Peter M.; Blaimer, Martin

    2014-01-01

    Purpose Cartesian turbo spin-echo (TSE) and radial TSE images are usually reconstructed by assembling data containing different contrast information into a single k-space. This approach results in mixed contrast contributions in the images, which may reduce their diagnostic value. The goal of this work is to improve the image contrast from radial TSE acquisitions by reducing the contribution of signals with undesired contrast information. Methods Radial TSE acquisitions allow the reconstruction of multiple images with different T2 contrasts using the k-space weighted image contrast (KWIC) filter. In this work, the image contrast is improved by reducing the band-width of the KWIC filter. Data for the reconstruction of a single image are selected from within a small temporal range around the desired echo time. The resulting data set is undersampled and therefore an iterative parallel imaging algorithm is applied to remove aliasing artifacts. Results Radial TSE images of the human brain reconstructed with the proposed method show an improved contrast when compared to Cartesian TSE images or radial TSE images with conventional KWIC reconstructions. Conclusion The proposed method provides multi-contrast images from radial TSE data with contrasts similar to multi spin-echo images. Contaminations from unwanted contrast weightings are strongly reduced. PMID:24436227

  15. Spin-dependent beating patterns in thermoelectric properties: Filtering the carriers of the heat flux in a Kondo adatom system

    NASA Astrophysics Data System (ADS)

    Seridonio, A. C.; Siqueira, E. C.; Franco, R.; Silva-Valencia, J.; Shelykh, I. A.; Figueira, M. S.

    2014-11-01

    We theoretically investigate the thermoelectric properties of a spin-polarized two-dimensional electron gas hosting a Kondo adatom hybridized with a STM tip. Such a setup is treated within the single-impurity Anderson model in combination with the atomic approach for the Green's functions. Due to the spin dependence of the Fermi wave numbers, the electrical and thermal conductances together with thermopower and Lorenz number reveal beating patterns as a function of the STM tip position in the Kondo regime. In particular, by tuning the lateral displacement of the tip with respect to the adatom vicinity, the temperature, and the position of the adatom level, one can change the sign of the Seebeck coefficient through charge and spin. This opens a possibility of the microscopic control of the heat flux analogously to that established for the electrical current.

  16. Observation of Intrinsic Magnus Force and Direct Detection of Chirality in Superfluid 3He-A

    NASA Astrophysics Data System (ADS)

    Ikegami, Hiroki; Tsutsumi, Yasumasa; Kono, Kimitoshi

    2015-04-01

    We report details of the observation of the intrinsic Magnus (IM) force acting on negative and positive ions trapped just below a free surface of the A phase of superfluid 3He (3He-A). From the transport measurements of the ions along the surface, we found that the IM force acts on both the negative and positive ions. We also demonstrate that the transport measurements could distinguish whether the surface is composed of a chiral monodomain or multiple chiral domains. For multiple chiral domains, the current of the ions was found to be irreproducible and unstable, which was reasonably explained by the formation of the chiral domain structure and the dynamics of the chiral domain walls. For chiral monodomains, the appearance ratio of chirality emerging upon cooling through the superfluid transition temperature was found to depend on the direction of the external magnetic field, which implies the existence of an unknown coupling between the chirality and the magnetic field.

  17. Effect of temperature on performance of {sup 3}He filled neutron proportional counters

    SciTech Connect

    Desai, Shraddha S.

    2014-04-24

    Neutron detectors used for cosmic neutron monitoring and various other applications are mounted in hostile environment. It is essential for detectors to sustain extreme climatic conditions, such as extreme temperature and humidity. Effort is made to evaluate the performance of detectors in extreme temperature in terms of pulse height distribution and avalanche formation. Neutron detectors filled with {sup 3}He incorporate an additive gas with quantity optimized for a particular application. Measurements are performed on neutron detectors filled with {sup 3}He and stopping gases Kr and CF{sub 4}. Detector performance for these fill gas combinations in terms of pulse height distribution is evaluated. Gas gain and Diethorn gas constants measured and analyzed for the microscopic effect on pulse formation. Results from these investigations are presented.

  18. [sup 3]He neutron detector performance in mixed neutron gamma environments

    SciTech Connect

    Johnson, N. H.; Beddingfield, D. H.

    2002-01-01

    A test program of the performance of 3He neutron proportional detectors with varying gas pressures, and their response to lligh level gamma-ray exposure in a mixed neutrodgamma environment, ha$ been performed Our intent was to identie the optimal gas pressure to reduce the gamma-ray sensitivity of these detectors. These detectors were manufxtured using materials to minimize their gamma response. Earlier work focused on 3He fill pressures of four atmospheres and above, whereas the present work focuses on a wider range of pressures. Tests have shown that reducing the .filling pressure will M e r increase the gamma-ray dose range in which the detectors can be operated.

  19. WORM ALGORITHM PATH INTEGRAL MONTE CARLO APPLIED TO THE 3He-4He II SANDWICH SYSTEM

    NASA Astrophysics Data System (ADS)

    Al-Oqali, Amer; Sakhel, Asaad R.; Ghassib, Humam B.; Sakhel, Roger R.

    2012-12-01

    We present a numerical investigation of the thermal and structural properties of the 3He-4He sandwich system adsorbed on a graphite substrate using the worm algorithm path integral Monte Carlo (WAPIMC) method [M. Boninsegni, N. Prokof'ev and B. Svistunov, Phys. Rev. E74, 036701 (2006)]. For this purpose, we have modified a previously written WAPIMC code originally adapted for 4He on graphite, by including the second 3He-component. To describe the fermions, a temperature-dependent statistical potential has been used. This has proven very effective. The WAPIMC calculations have been conducted in the millikelvin temperature regime. However, because of the heavy computations involved, only 30, 40 and 50 mK have been considered for the time being. The pair correlations, Matsubara Green's function, structure factor, and density profiles have been explored at these temperatures.

  20. High-3He plume origin and temporal-spatial evolution of the Siberian flood basalts

    USGS Publications Warehouse

    Basu, A.R.; Poreda, R.J.; Renne, P.R.; Teichmann, F.; Vasiliev, Y.R.; Sobolev, N.V.; Turrin, B.D.

    1995-01-01

    An olivine nephelinite from the lower part of a thick alkalic ultrabasic and mafic sequence of volcanic rocks of the northeastern part of the Siberian flood basalt province (SFBP) yielded a 40ArX39Ar plateau age of 253.3 ?? 2.6 million years, distinctly older than the main tholeiitic pulse of the SFBP at 250.0 million years. Olivine phenocrysts of this rock showed 3He/4He ratios up to 12.7 times the atmospheric ratio; these values suggest a lower mantle plume origin. The neodymium and strontium isotopes, rare earth element concentration patterns, and cerium/lead ratios of the associated rocks were also consistent with their derivation from a near-cnondritic, primitive plume. Geochemical data from the 250-million-year-old volcanic rocks higher up in the sequence indicate interaction of this high-3He SFBP plume with a suboceanic-type upper mantle beneath Siberia.

  1. Gadolinium Thin Foils in a Plasma Panel Sensor as an Alternative to 3He

    SciTech Connect

    Varner Jr, Robert L; Beene, James R; Friedman, Dr. Peter S.

    2010-01-01

    Gadolinium has long been investigated as a detector for neutrons. It has a thermal neutron capture cross-section that is unparalleled among stable elements, because of the isotopes $^{155,157}$Gd. As a replacement for $^3$He, gadolinium has a significant defect, it produces many gamma-rays with an energy sum of 8 MeV. It also produces conversion electrons, mostly 29 keV in energy. The key to replacing $^3$He with gadolinium is using a gamma-blind electron detector to detect the conversion electrons. We suggest that coupling a layer of gadolinium to a Plasma Panel Sensor (PPS) can provide highly efficient, nearly gamma-blind detection of the conversion. The PPS is a proposed detector under development as a dense array of avalanche counters based on plasma display technology. We will present simulations of the response of prototypes of this detector and considerations of the use of gadolinium in the PPS.

  2. Compulsory Deep Mixing of 3He and CNO Isotopes on the First Giant Branch

    SciTech Connect

    Eggleton, P P; Dearborn, D P; Lattanzio, J

    2007-07-26

    We have found a deep-mixing process which occurs during First Giant Branch (FGB) evolution. It begins at the point in evolution where the surface convection zone (SCZ), having previously grown in size, starts to shrink, and it is driven by a local minimum that develops in the mean molecular weight as a result of the burning of {sup 3}He. This mixing can solve two important observational problems. One is why the interstellar medium (ISM) has not been considerably enriched in {sup 3}He since the Big Bang. The other is why products of nucleosynthesis such as {sup 13}C are progressively enriched on the upper FGB, when classical stellar modeling says that no further enrichment should take beyond the First Dredge-Up (FDU) episode, somewhat below the middle of the FGB.

  3. Cross section calculations of medical 103Pd radioisotope using α and 3He induced reactions

    NASA Astrophysics Data System (ADS)

    Demir, Bayram; Sarpün, Ismail Hakkı; Dogan, Yunus Emre

    2016-11-01

    One of the most popular radioisotopes used in the prostate brachytherapy is Palladium-103 (103Pd). The radioactive plaque is sewn onto the eye as to cover the intraocular tumor shadow with a 2-3 mm margin. These plaques are temporary and radiation is continuously delivered over 5 to 7 days. At the end of treatment, the plaque is removed from eye. In this study, production cross-section calculations of 103Pd radionuclide used in brachytherapy produced by 101Ru(α,2n), 100Ru(α,n), 102Ru(3He,2n) and 101Ru(3He,n) reactions have been investigated in the different incident energy range up to 35 MeV. Twocomponent Exciton model and Generalized Superfluid model of the TALYS 1.6 code used to perform calculations and calculation results were compared with experimental results reported in the literature.

  4. Apatite 4He/3He and (U-Th)/He evidence for an ancient Grand Canyon.

    PubMed

    Flowers, R M; Farley, K A

    2012-12-21

    The Grand Canyon is one of the most dramatic features on Earth, yet when and why it was carved have been controversial topics for more than 150 years. Here, we present apatite (4)He/(3)He thermochronometry data from the Grand Canyon basement that tightly constrain the near-surface cooling history associated with canyon incision. (4)He/(3)He spectra for eastern Grand Canyon apatites of differing He date, radiation damage, and U-Th zonation yield a self-consistent cooling history that substantially validates the He diffusion kinetic model applied here. Similar data for the western Grand Canyon provide evidence that it was excavated to within a few hundred meters of modern depths by ~70 million years ago (Ma), in contrast to the conventional model in which the entire canyon was carved since 5 to 6 Ma.

  5. Stability and dissipation of laminar vortex flow in superfluid 3He-B.

    PubMed

    Eltsov, V B; de Graaf, R; Heikkinen, P J; Hosio, J J; Hänninen, R; Krusius, M; L'vov, V S

    2010-09-17

    A central question in the dynamics of vortex lines in superfluids is dissipation on approaching the zero temperature limit T→0. From both NMR measurements and vortex filament calculations, we find that vortex flow remains laminar up to large Reynolds numbers Re{α}∼10(3) in a cylinder filled with 3He-B. This is different from viscous fluids and superfluid 4He, where the corresponding responses are turbulent. In 3He-B, laminar vortex flow is possible in the bulk volume even in the presence of sizable perturbations from axial symmetry to below 0.2Tc. The laminar flow displays no excess dissipation beyond mutual friction, which vanishes in the T→0 limit, in contrast with turbulent vortex motion where dissipation has been earlier measured to approach a large T-independent value at T≲0.2Tc.

  6. Separation of magnetization precession in 3He-B into two magnetic domains. Theory

    NASA Astrophysics Data System (ADS)

    Fomin, I. A.

    It is shown that even small deviations of the magnetic field from uniformity can substantially modify the magnetization precession in 3He-B. Specifically, a two-domain structure forms if the magnetic-field non-uniformity is linear. The magnetization makes an angle ˜ 104° with the field in one of the domains and is parallel to it in the other. These domains can explain the anomalously long persistence of the induction signal in 3He-B; moreover, the change in the induction-signal frequency with time discovered and investigated by Borovik-Romanov et al. [JETP Lett. 40, 1033 (1984)] is a consequence of the relaxation of the domain structure.

  7. Dynamics of {sup 3}He impurities in {sup 4}He films

    SciTech Connect

    Clements, B.E. |; Krotscheck, E. |; Saarela, M.

    1995-08-01

    Using a microscopic variational theory the authors calculate the binding energy of {sup 3}He impurities in films of {sup 4}He absorbed to a graphite substrate. Without adjustable parameters, they obtain excellent agreement with the experimental binding energies for the ground state of the {sup 3}He impurity. To calculate excited states, they then introduce a time-dependent variational wave function. In that way, the impurity acquires a hydrodynamic effective mass for its motion parallel to the surface due to hydrodynamic backflow. Excited states have a finite lifetime. When these effects are included, both the energy of the first excited state of the impurity, and the effective mass of the ground state, also agree well with experimental data.

  8. A Variable Path Length Cell for Transverse Acoustic Studies of Superfluid 3He

    NASA Astrophysics Data System (ADS)

    Collett, C. A.; Nguyen, M. D.; Li, J. I. A.; Zimmerman, A. M.; Halperin, W. P.; Davis, J. P.

    2015-03-01

    Transverse sound has recently emerged as an effective probe of the order parameter of superfluid 3He. Both the transverse acoustic impedance and attenuation have been shown to couple to surface bound states in 3He- B, which are predicted to be Majorana states in the specular scattering limit. In order to measure the attenuation at different path lengths to separate surface from bulk effects, as well as reduce the cavity size to the micron scale where transverse sound propagation should be measurable in the normal state, we have constructed a variable path length cell. Using a 4He-actuated diaphragm we demonstrate in-situ changes to the cavity length at dilution temperatures, and report our progress in deploying the cell at sub-mK temperatures. This research was supported by the National Science Foundation grant DMR-1103625.

  9. Thermal Transport by Ballistic Quasiparticles in Superfluid 3He-B in the Low Temperature Limit

    SciTech Connect

    Bradley, D. I.; Fisher, S. N.; Guenault, A. M.; Haley, R. P.; Martin, H.; Pickett, G. R.; Roberts, J. E.; Tsepelin, V.

    2006-09-07

    In the temperature range below 0.2Tc, the gas of thermal excitations from the superfluid 3He-B ground state is in the ultra-dilute ballistic regime. Here we discuss preliminary measurements of the transport properties of this quasiparticle gas in a cell of cylindrical geometry with dimensions much smaller than any mean free path. The vertical cylinder, constructed from epoxy-coated paper, has vibrating wire resonator (VWR) heaters and thermometers at the top and bottom, and a small aperture at the top which provides the only exit for quasiparticles. Using the thermometer VWRs, we measure the difference in quasiparticle density between the top and bottom of the tube when we excite the top or bottom VWR heater. This gives information about the transport of energy along the cylindrical 3He sample and hence about the scattering behaviour involved when a quasiparticle impinges on the cylinder wall.

  10. Strong-coupling effects in superfluid {sup 3}He in aerogel

    SciTech Connect

    Aoyama, Kazushi; Ikeda, Ryusuke

    2007-09-01

    Effects of impurity scatterings on the strong-coupling (SC) contribution, stabilizing the ABM (axial) pairing state, to the quartic term of the Ginzburg-Landau free energy of superfluid {sup 3}He are theoretically studied to examine recent observations suggestive of an anomalously small SC effect in superfluid {sup 3}He in aerogels. To study the SC corrections, two approaches are used. One is based on a perturbation in the short-range repulsive interaction, and the other is a phenomenological approach used previously for the bulk liquid by Sauls and Serene [Phys. Rev. B 24, 183 (1981)]. It is found that the impurity scattering favors the BW pairing state and shrinks the region of the ABM pairing state in the T-P phase diagram. In the phenomenological approach, the resulting shrinkage of the ABM region is especially substantial and, if assuming an anisotropy over a large scale in aerogel, leads to justifying the phase diagrams determined experimentally.

  11. Particle transport in 3 He-rich events: wave-particle interactions and particle anisotropy measurements

    NASA Astrophysics Data System (ADS)

    Tsurutani, B. T.; Zhang, L. D.; Mason, G. L.; Lakhina, G. S.; Hada, T.; Arballo, J. K.; Zwickl, R. D.

    2002-04-01

    Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. 3 He-rich events are of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities. For 3 He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths l

  12. High-3He Plume Origin and Temporal-Spatial Evolution of the Siberian Flood Basalts.

    PubMed

    Basu, A R; Poreda, R J; Renne, P R; Teichmann, F; Vasiliev, Y R; Sobolev, N V; Turrin, B D

    1995-08-11

    An olivine nephelinite from the lower part of a thick alkalic ultrabasic and mafic sequence of volcanic rocks of the northeastern part of the Siberian flood basalt province (SFBP) yielded a (40)Ar/(39)Ar plateau age of 253.3 +/- 2.6 million years, distinctly older than the main tholeiitic pulse of the SFBP at 250.0 million years. Olivine phenocrysts of this rock showed (3)He/(4)He ratios up to 12.7 times the atmospheric ratio; these values suggest a lower mantle plume origin. The neodymium and strontium isotopes, rare earth element concentration patterns, and cerium/lead ratios of the associated rocks were also consistent with their derivation from a near-chondritic, primitive plume. Geochemical data from the 250-million-year-old volcanic rocks higher up in the sequence indicate interaction of this high-(3)He SFBP plume with a suboceanic-type upper mantle beneath Siberia.

  13. Surface Scattering Effect and the Stripe Order in Films of the Superfluid 3He B Phase

    NASA Astrophysics Data System (ADS)

    Aoyama, Kazushi

    2016-09-01

    Surface scattering effects in thin films of the superfluid 3He B phase have been theoretically investigated, with an emphasis on the stability of the stripe order with spontaneous broken translational symmetry in the film plane and quasiparticle excitations in this spatially inhomogeneous phase. Based on the Ginzburg-Landau theory in the weak coupling limit, we have shown that the stripe order, which was originally discussed for a film with two specular surfaces, can be stable in a film with one specular and one diffusive surfaces which should correspond to superfluid 3He on a substrate. It is also found by numerically solving the Eilenberger equation that due to the stripe structure, a midgap state distinct from the surface Andreev bound state emerges and its signature is reflected in the local density of states.

  14. On the optimisation of the use of 3He in radiation portal monitors

    NASA Astrophysics Data System (ADS)

    Tomanin, Alice; Peerani, Paolo; Janssens-Maenhout, Greet

    2013-02-01

    Radiation Portal Monitors (RPMs) are used to detect illicit trafficking of nuclear or other radioactive material concealed in vehicles, cargo containers or people at strategic check points, such as borders, seaports and airports. Most of them include neutron detectors for the interception of potential plutonium smuggling. The most common technology used for neutron detection in RPMs is based on 3He proportional counters. The recent severe shortage of this rare and expensive gas has created a problem of capacity for manufacturers to provide enough detectors to satisfy the market demand. In this paper we analyse the design of typical commercial RPMs and try to optimise the detector parameters in order either to maximise the efficiency using the same amount of 3He or minimise the amount of gas needed to reach the same detection performance: by reducing the volume or gas pressure in an optimised design.

  15. Nuclear structure corrections for μ4He+ and μ3He+ spectroscopy

    NASA Astrophysics Data System (ADS)

    Nevo Dinur, Nir; Ji, Chen; Hernandez, Oscar; Bacca, Sonia; Barnea, Nir

    2016-09-01

    The proton charge radius was recently determined from muonic hydrogen spectroscopy with tenfold improved precision but 7 . 9 σ disagreement with the accepted value, leading to the ``proton radius puzzle''. To further investigate, and to obtain precise radii, these measurements were repeated in μ4He+ and μ3He+. This may also shed light on the discrepancy between isotope-shift measurements of the 4He -3He radius difference. However, the precision of radii determined from the muonic experiments is limited by the uncertainties in the nuclear structure corrections. We present first ab-initio calculations of these corrections that reduced the uncertainties from 20 % to the few percent goal. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. This work was supported in parts by the Natural Sciences and Engineering Research Council (Grant Number SAPIN-2015-00031).

  16. Decoupling of first sound from second sound in dilute 3He-superfluid 4He mixtures

    NASA Astrophysics Data System (ADS)

    Riekki, T. S.; Manninen, M. S.; Tuoriniemi, J. T.

    2016-12-01

    Bulk superfluid helium supports two sound modes: first sound is an ordinary pressure wave, while second sound is a temperature wave, unique to superfluid systems. These sound modes do not usually exist independently, but rather variations in pressure are accompanied by variations in temperature, and vice versa. We studied the coupling between first and second sound in dilute 3He -superfluid 4He mixtures, between 1.6 and 2.2 K, at 3He concentrations ranging from 0% to 11%, under saturated vapor pressure, using a quartz tuning fork oscillator. Second sound coupled to first sound can create anomalies in the resonance response of the fork, which disappear only at very specific temperatures and concentrations, where two terms governing the coupling cancel each other, and second sound and first sound become decoupled.

  17. Fast-Neutron Spectrometry Using a 3He Ionization Chamber and Digital Pulse Shape Analysis

    SciTech Connect

    D. L. Chichester; J. T. Johnson; E. H. Seabury

    2010-05-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type 3He proportional counter to measure the fast neutron spectra of bare 252Cf and 241AmBe neutron sources. Measurements have also been made to determine the attenuated fast neutron spectra of 252Cf shielded by several materials including water, graphite, liquid nitrogen, magnesium, and tungsten. Rise-time dPSA has been employed using the common rise-time approach for analyzing n +3He ? 1H + 3H ionization events and a new approach has been developed to improve the fidelity of these measurements. Simulations have been performed for the different experimental arrangements and are compared, demonstrating general agreement between the dPSA processed fast neutron spectra and predictions.

  18. Hyperfine suppression of 2 {sup 3}S{sub 1} - 3 {sup 3}P{sub J} transitions in {sup 3}He.

    SciTech Connect

    Sulai, A.; Wu, Q.; Bishof, M.; Drake, G. W. F.; Lu, Z.-T.; Mueller, P.; Santra, R.; Univ. of Chicago; Univ. of Winsdor

    2008-01-01

    Two anomalously weak transitions within the 2{sup 3}S{sub 1}-3{sup 3}P{sub J} manifolds in {sup 3}He have been identified. Their transition strengths are measured to be 1000 times weaker than that of the strongest transition in the same group. This dramatic suppression of transition strengths is due to the dominance of the hyperfine interaction over the fine-structure interaction. An alternative selection rule based on IS coupling (where the nuclear spin is first coupled to the total electron spin) is proposed. This provides qualitative understanding of the transition strengths. It is shown that the small deviations from the IS coupling model are fully accounted for by an exact diagonalization of the strongly interacting states.

  19. In vivo lung morphometry with hyperpolarized 3He diffusion MRI: theoretical background.

    PubMed

    Sukstanskii, A L; Yablonskiy, D A

    2008-02-01

    MRI-based study of (3)He gas diffusion in lungs may provide important information on lung microstructure. Lung acinar airways can be described in terms of cylinders covered with alveolar sleeve [Haefeli-Bleuer, Weibel, Anat. Rec. 220 (1988) 401]. For relatively short diffusion times (on the order of a few ms) this geometry allows description of the (3)He diffusion attenuated MR signal in lungs in terms of two diffusion coefficients-longitudinal (D(L)) and transverse (D(T)) with respect to the individual acinar airway axis [Yablonskiy et al., PNAS 99 (2002) 3111]. In this paper, empirical relationships between D(L) and D(T) and the geometrical parameters of airways and alveoli are found by means of computer Monte Carlo simulations. The effects of non-Gaussian signal behavior (dependence of D(L) and D(T) on b-value) are also taken into account. The results obtained are quantitatively valid in the physiologically important range of airway parameters characteristic of healthy lungs and lungs with mild emphysema. In lungs with advanced emphysema, the results provide only "apparent" characteristics but still could potentially be used to evaluate emphysema progression. This creates a basis for in vivo lung morphometry-evaluation of the geometrical parameters of acinar airways from hyperpolarized (3)He diffusion MRI, despite the airways being too small to be resolved by direct imaging. These results also predict a rather substantial dependence of (3)He ADC on the experimentally-controllable diffusion time, Delta. If Delta is decreased from 3 ms to 1 ms, the ADC in normal human lungs may increase by almost 50%. This effect should be taken into account when comparing experimental data obtained with different pulse sequences.

  20. Mass superflux in solid helium: The role of 3He impurities

    NASA Astrophysics Data System (ADS)

    Vekhov, Ye.; Hallock, R. B.

    2015-09-01

    Below ˜630 mK, the 4He atom mass flux F , which passes through a cell filled with solid hcp 4He in the pressure range 25.6-26.4 bar, rises with falling temperature and, at a temperature Td, the flux drops sharply. The flux above Td has characteristics that are consistent with the presence of a bosonic Luttinger liquid. We study F as a function of 3He concentration, χ =0.17 -220 ppm , to explore the effect of 3He impurities on the mass flux. We find that the strong reduction of the flux is a sharp transition, typically complete within a few mK and a few hundred seconds. Modest concentration-dependent hysteresis is present. We find that Td is an increasing function of χ and the Td(χ ) dependence differs somewhat from the predictions for bulk phase separation for Tp s vs χ . We conclude that 3He plays an important role in the flux extinction. The dependence of F on the solid helium density is also studied. We find that F is sample dependent, but that the temperature dependence of F above Td is universal; data for all samples scale and collapse to a universal temperature dependence, independent of 3He concentration or sample history. The universal behavior extrapolates to zero flux in the general vicinity of Th≈630 mK . With increases in temperature, it is possible that a thermally activated process contributes to the degradation of the flux. The possibility of the role of disorder and the resulting phase slips as quantum defects on one-dimensional conducting pathways is discussed.

  1. Search for a bound trineutron with the 3He(π-pgr;+)nnn reaction

    NASA Astrophysics Data System (ADS)

    Gräter, J.; Amaudruz, P. A.; Bilger, R.; Camerini, P.; Clark, J.; Clement, H.; Friedman, E.; Felawka, L.; Filippov, S. N.; Friagiacomo, E.; Gavrilov, Y. K.; Gibson, E.; Grion, N.; Hofman, G. J.; Jamieson, B.; Karavicheva, T. L.; Kermanipresent Address: Sonigistix Corporation, Richmond, B. C., Canada V7A-5E3-->, M.; Mathie, E. L.; Meier, R.; Moloney, G.; Ottewell, D.; Pätzold, J.; Patarakin, O.; Raywood, K.; Rui, R.; Schepkin, M.; Sevior, M. E.; Smith, G. R.; Staudenmaier, H.; Tacik, R.; Tagliente, G.; Wagner, G. J.; Yeomans, M.

    1999-01-01

    A search for the production of a bound trineutron state has been performed using the reaction 3He(π-,π+)nnn at incident pion energies of 65, 75, and 120 MeV. No evidence for the existence of the 3n was found, and an upper limit for the production cross section of approximately 30 nb/sr (2σ confidence level) was obtained.

  2. Direct measurements of the magnetic field induced by optically polarized sup 3 He atoms

    SciTech Connect

    Gudoshnikov, S.A.; Snigirev, O.V. ); Kozlov, A.N.; Maslennikov, Y.V.; Serebrjakov, A.Y. )

    1991-03-01

    This paper reports on an alternative magnetic field induced by the standard cell of the optically pumped {sup 3}He magnetometer directly measured by the SQUID-based second-order gradiometer with signal-to-noise ratio higher than 6. The magnitude of the measured field equal to 5 {times} 10{sup {minus}13} T at the 5-cm distance from the cell axis and transverse relaxation time T{sub 2} equal to 7 minutes have been found.

  3. In vivo lung morphometry with hyperpolarized 3He diffusion MRI: Theoretical background

    NASA Astrophysics Data System (ADS)

    Sukstanskii, A. L.; Yablonskiy, D. A.

    2008-02-01

    MRI-based study of 3He gas diffusion in lungs may provide important information on lung microstructure. Lung acinar airways can be described in terms of cylinders covered with alveolar sleeve [Haefeli-Bleuer, Weibel, Anat. Rec. 220 (1988) 401]. For relatively short diffusion times (on the order of a few ms) this geometry allows description of the 3He diffusion attenuated MR signal in lungs in terms of two diffusion coefficients—longitudinal (D) and transverse (D) with respect to the individual acinar airway axis [Yablonskiy et al., PNAS 99 (2002) 3111]. In this paper, empirical relationships between D and D and the geometrical parameters of airways and alveoli are found by means of computer Monte Carlo simulations. The effects of non-Gaussian signal behavior (dependence of D and D on b-value) are also taken into account. The results obtained are quantitatively valid in the physiologically important range of airway parameters characteristic of healthy lungs and lungs with mild emphysema. In lungs with advanced emphysema, the results provide only "apparent" characteristics but still could potentially be used to evaluate emphysema progression. This creates a basis for in vivo lung morphometry—evaluation of the geometrical parameters of acinar airways from hyperpolarized 3He diffusion MRI, despite the airways being too small to be resolved by direct imaging. These results also predict a rather substantial dependence of 3He ADC on the experimentally-controllable diffusion time, Δ. If Δ is decreased from 3 ms to 1 ms, the ADC in normal human lungs may increase by almost 50%. This effect should be taken into account when comparing experimental data obtained with different pulse sequences.

  4. A Density Functional for Liquid 3He Based on the Aziz Potential

    NASA Astrophysics Data System (ADS)

    Barranco, M.; Hernández, E. S.; Mayol, R.; Navarro, J.; Pi, M.; Szybisz, L.

    2006-09-01

    We propose a new class of density functionals for liquid 3He based on the Aziz helium-helium interaction screened at short distances by the microscopically calculated two-body distribution function g(r). Our aim is to reduce to a minumum the unavoidable phenomenological ingredients inherent to any density functional approach. Results for the homogeneous liquid and droplets are presented and discussed.

  5. Elastic proton scattering on tritium below the n-{sup 3}He threshold

    SciTech Connect

    Lazauskas, Rimantas

    2009-05-15

    Elastic proton scattering on the {sup 3}H nucleus is studied between p-{sup 3}H and n-{sup 3}He thresholds, in the energy region where the first excited state of the {alpha} particle is embedded in the continuum. Faddeev-Yakubovski equations are solved in configuration space by fully considering effects from isospin breaking and rigorously treating the Coulomb interaction. Different realistic nuclear Hamiltonians are tested, elucidating open problems in the description of the nuclear interaction.

  6. Comparison of various stopping gases for 3He-based position sensitive neutron detectors

    NASA Astrophysics Data System (ADS)

    Doumas, A.; Smith, G. C.

    2012-05-01

    A range of solid state, scintillator and gas based detectors are being developed for use at the next generation of high flux neutron facilities. Since gas detectors are expected to continue to play a key role in future specific thermal neutron experiments, a comparison of the performance characteristics of prospective stopping gases is beneficial. Gas detectors typically utilize the reaction 3He(n,p)t to detect thermal neutrons; the 3He gas is used in a mixture containing a particular stopping gas in order to maintain relatively short ranges for the proton and triton pair emitted from the n-3He reaction. Common stopping gases include hydrocarbons (e.g. propane), carbon tetrafluoride, and noble gases such as argon and xenon. For this study, we utilized the Monte Carlo simulation code "Stopping and Range of Ions in Matter" to analyze the expected behavior of argon, xenon, carbon dioxide, difluoroethane and octafluoropropane as stopping gases for thermal neutron detectors. We also compare these findings to our previously analyzed performance of propane, butane and carbon tetrafluoride. A discussion of these gases includes their behavior in terms of proton and triton range, ionization distribution and straggle.

  7. Chiral effective field theory predictions for muon capture on deuteron and $^3$He

    SciTech Connect

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

    2012-01-01

    The muon-capture reactions {sup 2}H({mu}{sup -}, {nu}{sub {mu}})nn and {sup 3}He({mu}{sup -},{nu}{sub {mu}}){sup 3}H are studied with nuclear strong-interaction potentials and charge-changing weak currents, derived in chiral effective field theory. The low-energy constants (LEC's) c{sub D} and c{sub E}, present in the three-nucleon potential and (c{sub D}) axial-vector current, are constrained to reproduce the A=3 binding energies and the triton Gamow-Teller matrix element. The vector weak current is related to the isovector component of the electromagnetic current via the conserved-vector-current constraint, and the two LEC's entering the contact terms in the latter are constrained to reproduce the A=3 magnetic moments. The muon capture rates on deuteron and {sup 3}He are predicted to be 399 {+-} 3 sec{sup -1} and 1494 {+-} 21 sec{sup -1}, respectively, where the spread accounts for the cutoff sensitivity as well as uncertainties in the LEC's and electroweak radiative corrections. By comparing the calculated and precisely measured rates on {sup 3}He, a value for the induced pseudoscalar form factor is obtained in good agreement with the chiral perturbation theory prediction.

  8. Hyperpolarized 3He functional magnetic resonance imaging of bronchoscopic airway bypass in chronic obstructive pulmonary disease

    PubMed Central

    Mathew, Lindsay; Kirby, Miranda; Farquhar, Donald; Licskai, Christopher; Santyr, Giles; Etemad-Rezai, Roya; Parraga, Grace; McCormack, David G

    2012-01-01

    A 73-year-old exsmoker with Global initiative for chronic Obstructive Lung Disease stage III chronic obstructive pulmonary disease underwent airway bypass (AB) as part of the Exhale Airway Stents for Emphysema (EASE) trial, and was the only EASE subject to undergo hyperpolarized 3He magnetic resonance imaging for evaluation of lung function pre- and post-AB. 3He magnetic resonance imaging was acquired twice previously (32 and eight months pre-AB) and twice post-AB (six and 12 months post-AB). Six months post-AB, his increase in forced vital capacity was <12% predicted, and he was classified as an AB nonresponder. However, post-AB, he also demonstrated improvements in quality of life scores, 6 min walk distance and improvements in 3He gas distribution in the regions of stent placement. Given the complex relationship between well-established pulmonary function and quality of life measurements, the present case provides evidence of the value-added information functional imaging may provide in chronic obstructive pulmonary disease interventional studies. PMID:22332133

  9. Hyperpolarized 3He functional magnetic resonance imaging of bronchoscopic airway bypass in chronic obstructive pulmonary disease.

    PubMed

    Mathew, Lindsay; Kirby, Miranda; Farquhar, Donald; Licskai, Christopher; Santyr, Giles; Etemad-Rezai, Roya; Parraga, Grace; McCormack, David G

    2012-01-01

    A 73-year-old exsmoker with Global initiative for chronic Obstructive Lung Disease stage III chronic obstructive pulmonary disease underwent airway bypass (AB) as part of the Exhale Airway Stents for Emphysema (EASE) trial, and was the only EASE subject to undergo hyperpolarized 3He magnetic resonance imaging for evaluation of lung function pre- and post-AB. 3He magnetic resonance imaging was acquired twice previously (32 and eight months pre-AB) and twice post-AB (six and 12 months post-AB). Six months post-AB, his increase in forced vital capacity was <12% predicted, and he was classified as an AB nonresponder. However, post-AB, he also demonstrated improvements in quality of life scores, 6 min walk distance and improvements in 3He gas distribution in the regions of stent placement. Given the complex relationship between well-established pulmonary function and quality of life measurements, the present case provides evidence of the value-added information functional imaging may provide in chronic obstructive pulmonary disease interventional studies.

  10. Large {sigma} Channel Low-Mass Enhancement in Exclusively Measured Double Pionic Fusion to 3He

    SciTech Connect

    Bashkanov, M.; Skorodko, T.; Clement, H.; Khakimova, O.; Kren, F.; Wagner, G. J.

    2006-07-11

    The pd {yields} 3He {pi}0{pi}0 and pd {yields} 3He {pi}+{pi}- reactions have been measured exclusively at CELSIUS using the WASA 4{pi} detector with pellet target system. For the double-pionic fusion to 3He data have been taken at Tp = 0.893 GeV, where the maximum of the socalled ABC effect is expected. A very large low-mass enhancement is observed in the {pi}0{pi}0 invariant mass spectrum M{pi}0{pi}0, whereas only a moderate low-mass enhancement is seen in M{pi}+{pi}- raising thus the question of isospin invariance in this region. With both channels summed up the data agree well to previous inclusive measurements regarding the low-mass enhancement. However, they do not exhibit the high-mass enhancement seen in the inclusive measurements and predicted by theoretical calculations based on a {delta}{delta} process, which produces a double-hump structure in the M{pi}{pi} spectra.

  11. The penetration of tritium and generation of 3He in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Lott, D. E.; Jenkins, W. J.

    2007-12-01

    Based on large scale surveys such as GEOSECS, TTO, WOCE and CLIVAR, as well as smaller cruises, we now have observations that cover more nearly 35 years of the penetration of bomb-produced tritium and its daughter 3He in the North Atlantic Ocean. This data set offers us the opportunity to characterize the decade time-scale ventilation and circulation of the North Atlantic basin, and some insights into climate change and variability. Perhaps the most important aspect of this tracer pair is that the tritiugenic 3He is a unique transient tracer in that it highlights the return pathways of the ventilation process. This permits us to use it to constrain large scale fluxes of remineralized thermocline nutrients to the surface ocean, thus constraining basin scale new production. We describe the patterns of evolving tritium and 3He distributions within the subtropical North Atlantic and relate these to large scale circulation and ventilation. In addition, the evolving inventories of these tracers provide useful insights into the character of the meridional overturning circulation.

  12. Magnetism of Two-Dimensional Films of 3He on Highly Oriented Graphite

    NASA Astrophysics Data System (ADS)

    Bozler, H. M.; Zhang, Jinshan; Guo, Lei; Du, Yuliang; Gould, C. M.

    2006-09-01

    What is the effect of the structural length scale on the ordering of 3He films? NMR experiments on the magnetism of second layer 3He on Grafoil in the low field limit found ferromagnetic ordering for coverages over 20 atoms/nm2. Finite temperature phase transitions are prohibited in 2D when only Heisenberg interactions are present. However ordering of a two-dimensional magnetic film can be a result of a phase transition caused by weak anisotropy and/or dipolar interactions, or could be a less interesting manifestation of finite size effects. By replacing Grafoil with ZYX grade highly oriented graphite, we can study the magnetism of two-dimensional films with a substantially increased structural coherence length and test the importance of finite size effects. Our new experiments find a region of coverages where the second layer 3He films become ferromagnetic at temperatures above 1 mK, with no evidence for an increased suppression of the ordering due to increasing the coherence length. We show the results for the magnetism at a wide range of coverages as well as the effect of varying the magnetic field in the ferromagnetic cases. Our results support the interpretation in terms of a phase transition occurring at finite temperature.

  13. Gamma ray measurements during deuterium and /sup 3/He discharges on TFTR

    SciTech Connect

    Cecil, F.E.; Medley, S.S.

    1987-05-01

    Gamma ray count rates and energy spectra have been measured in TFTR deuterium plasmas during ohmic heating and during injection of deuterium neutral beams for total neutron source strengths up to 6 x 10/sup 15/ neutrons per second. The gamma ray measurements for the deuterium plasmas are in general agreement with predictions obtained using simplified transport models. The 16.6 MeV fusion gamma ray from the direct capture reaction D(/sup 3/He,..gamma..)/sup 5/Li was observed during deuterium neutral beam injection into /sup 3/He plasmas for beam powers up to 7 MW. The measured yield of the 16.6 MeV gamma ray is consistent with the predicted yield. The observation of this capture gamma ray establishes the spectroscopy of the fusion gamma rays from the D-/sup 3/He reactions as a viable diagnostic of total fusion reaction rates and benchmarks the modeling for extension of the technique to D-T plasmas. 21 refs., 12 figs.

  14. Development of 10B-Based 3He Replacement Neutron Detectors

    NASA Astrophysics Data System (ADS)

    King, Michael J.; Gozani, Tsahi; Hilliard, Donald B.

    2011-12-01

    Radiation portal monitors (RPM) are currently deployed at United States border crossings to passively inspect vehicles and persons for any emission of neutrons and/or gamma rays, which may indicate the presence of unshielded nuclear materials. The RPM module contains an organic scintillator with 3He proportional counters to detect gamma rays and thermalized neutrons, respectively. The supply of 3He is rapidly dwindling, requiring alternative detectors to provide the same function and performance. Our alternative approach is one consisting of a thinly-coated 10B flat-panel ionization chamber neutron detector that can be deployed as a direct drop-in replacement for current RPM 3He detectors. The uniqueness of our approach in providing a large-area detector is in the simplicity of construction, scalability of the unit cell detector, ease of adaptability to a variety of applications and low cost. Currently, Rapiscan Laboratories and Helicon Thin Film Systems have designed and developed an operational 100 cm2 multi-layer prototype 10BB-based ionization chamber.

  15. An accurate optical technique for measuring the nuclear polarisation of 3He gas

    NASA Astrophysics Data System (ADS)

    Talbot, C.; Batz, M.; Nacher, P.-J.; Tastevin, G.

    2011-06-01

    In the metastability exchange optical pumping cells of our on-site production unit and of our other experimental set-ups, we use a light absorption technique to measure the 3He nuclear polarisation. It involves weak probe beams at 1083 nm, that are either perpendicular or parallel to the magnetic field and cell axis, with suitable light polarisations. When metastability exchange collisions control the populations of the sublevels in the 23S state, absolute values of the 3He ground state nuclear polarisation are directly inferred from the ratio of the absorption rates measured for these probe beams. Our report focuses on the transverse detection scheme for which this ratio, measured at low magnetic field for σ and π light polarisations, hardly depends on gas pressure or the presence of an intense pump beam. This technique has been systematically tested both in pure 3He and isotopic mixtures and it is routinely used for accurate control of the optical pumping efficiency as well as for calibration of the NMR system.

  16. Differential cross sections for p+d-->γ+3He at intermediate energies

    NASA Astrophysics Data System (ADS)

    Briscoe, W. J.; Silverman, B. H.; Fitzgerald, D. H.; Nefkens, B. M. K.; Boudard, A.; Bruge, G.; Farvacque, L.; Glashausser, C.

    1985-12-01

    Differential cross sections have been measured for p+d-->γ+3He at Tp(lab)=300, 350, 400, 425, 450, 470, and 500 MeV for thetaγ(c.m.) near 60° and 90°. Measurements were also made for d+p-->γ+3He at Td=376 MeV for thetaγ(c.m.)=84°, 98°, and 113°, and at Td=600 MeV for thetaγ=96° and 105°. Our results are in agreement with those of the inverse reaction, γ+3He-->p+d of Sober et al., as is expected from time-reversal invariance. Our data agree with the latest results of Cameron et al. The older radiative capture measurements of Heusch et al. and the photodisintegration measurements made at other laboratories differ significantly from our results. Our data are compared with three theoretical models; the one proposed by Maximon and Prats comes closest to describing the data.

  17. Vertical groundwater flow estimated from the bomb pulse of 36Cl and tritiogenic 3He

    NASA Astrophysics Data System (ADS)

    Mahara, Y.; Ohta, T.

    2011-12-01

    The boring well was approximately excavated to 400 m depth from the ground surface on the tableland in the Central Shimokita Peninsula, Japan. Collecting pore-water, some fresh boring cores were sampled on the site during the excavation of borehole. Samples of groundwater were collected by using the sampling device with the water inflating packer system to protect various contaminations, after excavating the borehole. The atmospheric maximum concentration in bomb pulse in the northern hemisphere was reported to observe in 1955 for 36Cl and in 1963 for 3H, respectively. Since the half-life of 36Cl is much longer than 3H, the decay loss of 36Cl was negligible small for a short time until sampling groundwater in 2001 and 2003. On the other hand, the half-life of 3H is very short compared with that of 36Cl. Most of 3H was converted into the tritiogenic 3He in groundwater for the past 38 years after rainwater infiltrating toward the groundwater table. Profiles of dissolved 4He concentration, tritiogenic 3He and 36Cl/Cl ratio were observed in groundwater of the borehole. The total dissolved 4He concentration ranged from 5.8×10-8 at the ground surface to 7.5×10-8 ccSTP/g at the depth of 200 m below the ground surface and it was almost equilibrated with the atmospheric 4He in pore-water (Fig. 1). The bomb pulses of tritiogenic 3He and 36Cl were left from the depth of 101 m below the ground surface to the depth of 132 m, respectively (Figs. 2 and 3). There was a slight difference in the location between the bomb pulse of 36Cl and that of tritiogenic 3He. The downward flow velocity of groundwater were simply estimated to be 2.8 m/y from the marked position of bomb pulse in the profile of 36Cl/Cl ratio and to be 2.7 m/y from the position of the bomb pulse peak of tritiogenic 3He, separately. These two rough estimations were good agreed with each other. The estimation suggests that the vertical flow of groundwater on the tableland is approximated with the downward piston

  18. A novel particle Time Of Flight (pTOF) diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF

    SciTech Connect

    Mackinnon, A; Rinderknecht, H G; Johnson, M G; Zylstra, A B; Sinenian, N; Rosenbergh, M J; Frenje, J A; Waugh, C J; Li, C K; Seguin, F H; Petrasso, R; Rygg, J R; Kline, J; Doeppner, T; Park, H S; Landen, O; Lepape, S; Meezan, N; Kilkenny, J; Glebov, V Y; Sangster, T; Stoeckl, C; Olson, R

    2012-05-02

    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.

  19. Calibration of cosmogenic 3He and 10Be production rates in the High Tropics

    NASA Astrophysics Data System (ADS)

    Blard, Pierre-Henri; Martin, Léo; Lavé, Jérôme; Charreau, Julien; Condom, Thomas; Lupker, Maarten; Braucher, Régis; Bourlès, Didier

    2014-05-01

    It is critical to refine both the accuracy and the precision of the in situ cosmogenic dating tool, especially for establishing reliable glacial chronologies that can be compared to other paleoclimatic records. Recent cross-calibrations of cosmogenic 3He in pyroxene and 10Be in quartz [1, 2] showed that, both at low (1300 m) and high elevation (4850 m), the 3He/10Be production ratio was probably ~40% higher than the value of ~23 initially defined in the 90's. This recent update is consistent with the last independent determinations of the sea level high latitude production rates of 10Be and 3He, that are about 4 and 125 at.g-1.yr-1, respectively [e.g. 3, 4]. However, major questions remain about these production rates at high elevation, notably because existing calibration sites for both 3He and 10Be are scarce above 2000 m. It is thus crucial to produce new high precision calibration data at high elevation. Here we report cosmogenic 10Be data from boulders sampled on a glacial fan located at 3800 m in the Central Altiplano (Bolivia), whose age is independently constrained by stratigraphic correlations and radiocarbon dating at ca. 16 ka. These data can be used to calibrate the production rate of 10Be at high elevation, in the Tropics. After scaling to sea level and high latitude, these data yield a sea level high latitude P10 ranging from 3.8 to 4.2 at.g-1.yr-1, depending on the used scaling scheme. These new calibration data are in good agreement with recent absolute and cross-calibration of 3He in pyroxenes and 10Be in quartz, from dacitic moraines located at 4850 m in the Southern Altiplano (22° S, Tropical Andes) [2,5]. The so-obtained 3He/10Be production ratio of 33.3±0.9 (1σ) combined with an absolute 3He production rate locally calibrated in the Central Altiplano, at 3800 m, indeed yielded a sea level high latitude P10 ranging from 3.7±0.2 to 4.1±0.2 at.g-1.yr-1, depending on the scaling scheme [2,5]. These values are also consistent with the 10Be

  20. Development of spatial-temporal ventilation heterogeneity and probability analysis tools for hyperpolarized 3He magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Choy, S.; Ahmed, H.; Wheatley, A.; McCormack, D. G.; Parraga, G.

    2010-03-01

    We developed image analysis tools to evaluate spatial and temporal 3He magnetic resonance imaging (MRI) ventilation in asthma and cystic fibrosis. We also developed temporal ventilation probability maps to provide a way to describe and quantify ventilation heterogeneity over time, as a way to test respiratory exacerbations or treatment predictions and to provide a discrete probability measurement of 3He ventilation defect persistence.

  1. Apatite 4He/3He thermochronometry evidence for an ancient Grand Canyon, Colorado Plateau, USA

    NASA Astrophysics Data System (ADS)

    Flowers, R. M.; Farley, K. A.

    2012-12-01

    The very existence of Grand Canyon inspires questions about why canyons are carved, how drainage systems and landscapes evolve, and how these processes relate to the elevation gain of plateaus. Yet when and why Grand Canyon was carved have been extraordinarily controversial for more than 150 years. Over the last several decades, the dominant view for the origin of the canyon is one of rapid incision at 5-6 Ma, when detritus derived from the upstream reaches of the Colorado River system appeared in Grand Wash Trough at the Colorado River's western exit from the Colorado Plateau. The absence of such diagnostic deposits prior to 6 Ma has been used to argue that Grand Canyon was not yet excavated (e.g., Karlstrom et al., 2008). However, a variety of data hint at a more ancient age for part or all of the canyon, and it has been proposed that a smaller drainage basin in largely carbonate lithologies could explain the absence of pre-6 Ma Colorado River clastics in Grand Wash Trough even if a significant Grand Canyon were present. Most recently, apatite (U-Th)/He (AHe) thermochronometry data from western Grand Canyon were used to infer excavation of this area to within several hundred meters of its modern depth by ca. 70 Ma (Wernicke, 2011), an interpretation in direct conflict with the young canyon model. The unexpected implications of the initial Grand Canyon AHe work motivated the apatite 4He/3He and U-Th zonation study presented here. Apatite 4He/3He thermochronometry provides information about the spatial distribution of radiogenic 4He in an apatite crystal that can better constrain a sample's cooling history. A key premise of AHe and 4He/3He spectra interpretation is that the He kinetic model used is accurate. We first investigate whether differing 4He/3He spectra for apatites of variable AHe date, radiation damage, and U-Th zonation from eastern Grand Canyon yield mutually consistent thermal history results using the RDAAM kinetic model, which must be true if the

  2. Safety analysis of high pressure 3He-filled micro-channels for thermal neutron detection.

    SciTech Connect

    Ferko, Scott M.; Galambos, Paul C.; Derzon, Mark Steven; Renzi, Ronald F.

    2008-11-01

    This document is a safety analysis of a novel neutron detection technology developed by Sandia National Laboratories. This technology is comprised of devices with tiny channels containing high pressure {sup 3}He. These devices are further integrated into large scale neutron sensors. Modeling and preliminary device testing indicates that the time required to detect the presence of special nuclear materials may be reduced under optimal conditions by several orders of magnitude using this approach. Also, these devices make efficient use of our {sup 3}He supply by making individual devices more efficient and/or extending the our limited {sup 3}He supply. The safety of these high pressure devices has been a primary concern. We address these safety concerns for a flat panel configuration intended for thermal neutron detection. Ballistic impact tests using 3 g projectiles were performed on devices made from FR4, Silicon, and Parmax materials. In addition to impact testing, operational limits were determined by pressurizing the devices either to failure or until they unacceptably leaked. We found that (1) sympathetic or parasitic failure does not occur in pressurized FR4 devices (2) the Si devices exhibited benign brittle failure (sympathetic failure under pressure was not tested) and (3) the Parmax devices failed unacceptably. FR4 devices were filled to pressures up to 4000 + 100 psig, and the impacts were captured using a high speed camera. The brittle Si devices shattered, but were completely contained when wrapped in thin tape, while the ductile FR4 devices deformed only. Even at 4000 psi the energy density of the compressed gas appears to be insignificant compared to the impact caused by the incoming projectile. In conclusion, the current FR4 device design pressurized up to 4000 psi does not show evidence of sympathetic failure, and these devices are intrinsically safe.

  3. Linking Ventilation Heterogeneity Quantified via Hyperpolarized 3He MRI to Dynamic Lung Mechanics and Airway Hyperresponsiveness.

    PubMed

    Lui, Justin K; Parameswaran, Harikrishnan; Albert, Mitchell S; Lutchen, Kenneth R

    2015-01-01

    Advancements in hyperpolarized helium-3 MRI (HP 3He-MRI) have introduced the ability to render and quantify ventilation patterns throughout the anatomic regions of the lung. The goal of this study was to establish how ventilation heterogeneity relates to the dynamic changes in mechanical lung function and airway hyperresponsiveness in asthmatic subjects. In four healthy and nine mild-to-moderate asthmatic subjects, we measured dynamic lung resistance and lung elastance from 0.1 to 8 Hz via a broadband ventilation waveform technique. We quantified ventilation heterogeneity using a recently developed coefficient of variation method from HP 3He-MRI imaging. Dynamic lung mechanics and imaging were performed at baseline, post-challenge, and after a series of five deep inspirations. AHR was measured via the concentration of agonist that elicits a 20% decrease in the subject's forced expiratory volume in one second compared to baseline (PC20) dose. The ventilation coefficient of variation was correlated to low-frequency lung resistance (R = 0.647, P < 0.0001), the difference between high and low frequency lung resistance (R = 0.668, P < 0.0001), and low-frequency lung elastance (R = 0.547, P = 0.0003). In asthmatic subjects with PC20 values <25 mg/mL, the coefficient of variation at baseline exhibited a strong negative trend (R = -0.798, P = 0.02) to PC20 dose. Our findings were consistent with the notion of peripheral rather than central involvement of ventilation heterogeneity. Also, the degree of AHR appears to be dependent on the degree to which baseline airway constriction creates baseline ventilation heterogeneity. HP 3He-MRI imaging may be a powerful predictor of the degree of AHR and in tracking the efficacy of therapy.

  4. /sup 3/He constant-volume gas thermometry: calculations for a temperature scale between 0. 8 and 25 K

    SciTech Connect

    Pavese, F.; Steur, P.P.M.

    1987-10-01

    A discussion is presented on the possibilities of a /sup 3/He gas thermometer for defining a temperature scale below 30 K, based on recent new measurements of the virial coefficient. The influence of all corrections of interest is given in comparison with /sup 4/He gas thermometry and with /sup 4/He and /sup 3/He vapor pressure thermometry. It is shown that a /sup 3/He gas thermometer can be operated down to temperatures < 1 K, with an estimated inaccuracy of less than +/- 0.5 mK, thereby obviating the explicit need of the /sup 3/He and /sup 4/He vapor pressure scales below 5K, and directly joining a possible scale based on the /sup 3/He melting curve.

  5. Constraining the Astrophysical S Factor of the 3He(α,γ)7Be Reaction

    NASA Astrophysics Data System (ADS)

    Carmona-Gallardo, M.; Rojas, A.; Nara Singh, B. S.; Akers, C.; Aviv, O.; Borge, M. J. G.; Christian, G.; Davids, B.; Fallis, J.; Fulton, B. R.; Hager, U.; Haquin, G.; Hass, M.; Hutcheon, D. A.; Nir-El, Y.; Ottewell, D.; Ruiz, C.; Sjue, S. K. L.; Tengblad, O.; Yaniv, R.; Yungreis, Z.

    The cross section of the 3He(α,γ)7Be reaction has been widely studied both from the theoretical and the experimental fronts due to its relevance to the standard solar model and to the Big Bang Nucleosynthesis calculations. We report here on cross section measurements in the energy region Ec.m. = 1-3 MeV using the direct recoil counting method in an attempt to resolve the discrepancies among the previous data sets and calculations in this energy region and thus to constrain the extrapolations of the S34(E) curve to astrophysical energies.

  6. /sup 3/He nuclear gyroscope. Final report, November 1980-July 1985

    SciTech Connect

    Shaw, G.L.

    1985-08-01

    The /sup 3/He nuclear gyroscope is a single-species cryogenic device that can be instrumented as a three-degree-of-freedom gyroscope. Sensitivities to dynamic terms can be molded, measured, and compensated by generation of cross-axis magnetic fields. The magnetic-field-generation scheme is the equivalent of putting the gyro on a stabilized platform but requires no moving parts. Such a gyroscope would be most useful integrated with other cryogenic instruments in a high-accuracy all-cryogenic inertial measurement unit.

  7. Contrasting Mechanical Anisotropies of the Superfluid {sup 3}He Phases in Aerogel

    SciTech Connect

    Bradley, D. I.; Fisher, S. N.; Guenault, A. M.; Haley, R. P.; O'Sullivan, S.; Pickett, G. R.; Roberts, J.; Tsepelin, V.; Mulders, N.

    2007-02-16

    There has been much recent interest in how impurity scattering may affect the phases of the p-wave superfluid {sup 3}He. Impurities may be added to the otherwise absolutely pure superfluid by immersing it in aerogel. Some predictions suggest that impurity scattering may destroy orientational order and force all of the superfluid phases to have an isotropic superfluid density. In contrast to this, we present experimental data showing that the response of the A-like phase to superfluid flow is highly anisotropic, revealing a texture that is easily modified by flow.

  8. Decay of Pure Quantum Turbulence in Superfluid {sup 3}He-B

    SciTech Connect

    Bradley, D.I.; Clubb, D.O.; Fisher, S.N.; Guenault, A.M.; Haley, R.P.; Matthews, C.J.; Pickett, G.R.; Tsepelin, V.; Zaki, K.

    2006-01-27

    We describe measurements of the decay of pure superfluid turbulence in superfluid {sup 3}He-B, in the low temperature regime where the normal fluid density is negligible. We follow the decay of the turbulence generated by a vibrating grid as detected by vibrating wire resonators. Despite the absence of any classical normal fluid dissipation processes, the decay is consistent with turbulence having the classical Kolmogorov energy spectrum and is remarkably similar to that measured in superfluid {sup 4}He at relatively high temperatures. Further, our results strongly suggest that the decay is governed by the superfluid circulation quantum rather than kinematic viscosity.

  9. Bogoliubov-normal interaction and calculation of thermal conductivity of superfluid A1-3He

    NASA Astrophysics Data System (ADS)

    Afzali, R.; Ebrahimian, N.

    2006-09-01

    The diffusive thermal conductivity tensor of the A 1-phase of superfluid 3He at low temperatures and melting pressure are calculated by s-p approximation, by using the Boltzmann equation approach. We obtain that the elements of the diffusive thermal conductivities, Kxx, Kyy, and Kzz, are proportional to T -1. Then we compare the results of this paper and our results of thermal conductivity based on Pfitzner procedure. Temperature dependence of both results is equal but numerical coefficients of them are little different. Also we show that Boguliubov-normal interaction is important in comparison to other interactions.

  10. Paramagnon and Size Effects for T c in Superfluid 3He Films

    NASA Astrophysics Data System (ADS)

    Furukawa, Hitoshi; Ohmi, Tetsuo

    1999-12-01

    The symmetry of Cooper pairs and transition temperature T c ofsuperfluid 3 He films thinner than coherence length withspecularly reflecting boundary are investigated. Using the paramagnon model for the pairing interaction, we show thesymmetry of pairs is likely p-wave and the gap at T c is theABM (or Planer) type. The quantum size effect yields the oscillatingbehavior of T c as a function of the film thickness. On the contrary to the result of Tesanovic and Valls, the transition temperature weobtained is higher than that of the bulk system.

  11. sup 18 O( sup 3 He, p ) sup 20 F reaction

    SciTech Connect

    Chowdhury, M.S.; Zaman, M.A.; Sen Gupta, H.M. )

    1992-12-01

    The {sup 18}O({sup 3}He,{ital p}){sup 20}F reaction has been studied at 18 MeV. Energy levels are measured up to {ital E}{sub {ital x}}{similar to}8.5 MeV and several new levels are observed. Angular distributions are measured for many of the levels and distorted wave Born approximation analyses are carried out. The {ital L} assignments are made and {ital J}{sup {pi}} limits are obtained.

  12. Coordinated Observations of Energetic Particles from 3He-rich Events by STEREO and ACE

    NASA Astrophysics Data System (ADS)

    Wiedenbeck, M. E.; Mason, G. M.; Cohen, C. M.; Nitta, N. V.; Gomez-Herrero, R.; Haggerty, D. K.

    2012-12-01

    The two STEREOs, together with ACE and other near-Earth spacecraft, have produced data sets that are well suited for investigating how 3He-rich energetic particles that are accelerated in reconnection events on the Sun get distributed in heliographic longitude. Our earlier study[1] of one such 3He-rich event (7 February 2010), which was detected at ACE and both STEREOs when they spanned 136o, showed that accelerated particles can be distributed over a wide range of longitudes even when they originate from a localized solar source. In addition, the particle fluences were found to decrease strongly with increasing distance from the longitude having the best magnetic connection to the source region. Based on data from the first four years of the STEREO mission, when solar activity was very low, we have used additional 3He-rich events detected by one or both of the STEREO/LET instruments and, in some cases also by ACE/ULEIS and/or SIS, to investigate the conditions under which the accelerated particles can gain access to a wide range of heliographic longitudes and to determine the longitudinal dependences of particle fluences in such events. During 2011 and 2012, when the level of solar activity has been significantly greater than in the preceding four years, unambiguous association of events detected at different spacecraft has been hampered by the possibility of chance coincidences between detections of particles from separate solar events as well as by the increased energetic particle background levels. We have investigated the possibility that event characteristics such as composition can be use to confirm that some events detected at widely spaced locations are associated with the same injection at the Sun. Such associations have the potential to extend the longitude range over which 3He-rich events can be studied and also to investigate the solar-cycle dependence of longitudinal spreading. We will report results from the statistical study of events that occurred

  13. Specific heat of /sup 3/He in the Fermi-liquid region

    SciTech Connect

    Mayberry, M.C.; Phillips, N.E.

    1983-03-01

    A CMN thermometer has been calibrated by nuclear-orientation thermometry at low temperatures and He vapor-pressure thermometry at high temperatures. The calibration agrees well with the NBS temperature scale between 100 and 200 mK. Specific-heat data on /sup 3/He in the Fermi-liquid region obtained with this thermometer are in good agreement with recent measurements at Bell Laboratories. It is argued that discrepancies with other data can be understood on the basis of errors in the temperature scales on which they are based.

  14. Two-Nucleon Momentum Distributions Measured in 3He(e,e'pp)n

    SciTech Connect

    R.A. Niyazov; L.B. Weinstein; et al

    2004-02-01

    We have measured the 3He(e,e'pp)n reaction at 2.2 GeV over a wide kinematic range. The kinetic energy distribution for ''fast'' nucleons (p > 250 MeV/c) peaks where two nucleons each have 20% or less, and the third nucleon has most of the transferred energy. These fast pp and pn pairs are back-to-back with little momentum along the three-momentum transfer, indicating that they are spectators. Experimental and theoretical evidence indicates that we have measured distorted two-nucleon momentum distributions by striking the third nucleon and detecting the spectator correlated pair.

  15. Precision spectroscopy of kaonic {sup 3}He X-rays at J-PARC

    SciTech Connect

    Sato, M.; Fujiwara, Y.; Hashimoto, T.; Hayano, R. S.; Ishikawa, T.; Shi, H.; Suzuki, T.; Tatsuno, H.; Bhang, H.; Choi, Seonho; Tanida, K.; Cargnelli, M.; Ishiwatari, T.; Marton, J.; Wuenschek, B.; Zmeskal, J.; Curceanu, C.; Guaraldo, C.; Okada, S.; Vidal, A. Romero

    2011-10-24

    We will measure the X-rays from kaonic {sup 3}He 3d {yields} 2p transition with a precision below 2 eV. It can provide crucial information on the kaon-nucleus strong interaction. The experiment (J-PARC E17) will be performed as Day-1, which is one of the first experiments in the J-PARC hadron facility in the year 2011. An overview and the present status of the J-PARC E17 experiment are described.

  16. Long term experience with the “industrial” 3He vapour-pressure thermometer

    NASA Astrophysics Data System (ADS)

    Benda, V.; Vafeiadis, T.

    2017-02-01

    On the basis of very good experience with a prototype of a 3He vapour-pressure thermometer installed in the magnet feed box (MFB – prototype of LHC magnet test bench), an upgraded version of this thermometer was developed with emphasis on the improvement of its long term stability, reliability and “series” production. The thermometer is working typically around 1.9 K. This article summarises the key points of the prototype design, its upgrade leading to the “industrial/series” realization, the long term experience and the calibration crosscheck of these thermometers after 15 years of operation.

  17. Effect of a Quenched Disorder on the Order Parameter of Superfluid 3He

    SciTech Connect

    Fomin, I. A.

    2006-09-07

    As a consequence of continuous degeneracy of the order parameter of the superfluid 3He quenched disorder in a form of aerogel gives rise both to a disruption of the orientational long-range order of the condensate and to a significant change of the order parameter itself. There exist a class of quasi-isotropic order parameters which are not sensitive to the disorienting effect of aerogel. While the BW order parameter belongs to this class the ABM does not. A possible candidate for the order parameter of the observed A-like phase is discussed.

  18. Pairing states of superfluid {sup 3}He in uniaxially anisotropic aerogel

    SciTech Connect

    Aoyama, Kazushi; Ikeda, Ryusuke

    2006-02-01

    Stable pairing states of superfluid {sup 3}He in aerogel are examined in the case with a global uniaxial anisotropy which may be created by applying a uniaxial stress to the aerogel. Due to such a global anisotropy, the stability region of an Anderson-Brinkman-Morel (ABM) pairing state becomes wider. In a uniaxially stretched aerogel, the pure polar pairing state with a horizontal line node is predicted to occur, as a three-dimensional superfluid phase, over a measurable width just below the superfluid transition at T{sub c}(P). A possible relevance of the present results to the case with no global anisotropy is also discussed.

  19. Critical Velocity in the Presence of Surface Bound States in Superfluid 3He -B

    NASA Astrophysics Data System (ADS)

    Zheng, P.; Jiang, W. G.; Barquist, C. S.; Lee, Y.; Chan, H. B.

    2017-02-01

    A microelectromechanical oscillator with a gap of 1.25 μ m was immersed in superfluid 3He -B and cooled below 250 μ K at various pressures. Mechanical resonances of its shear motion were measured at various levels of driving force. The oscillator enters into a nonlinear regime above a certain threshold velocity. The damping increases rapidly in the nonlinear region and eventually prevents the velocity of the oscillator from increasing beyond the critical velocity which is much lower than the Landau critical velocity. We propose that this peculiar nonlinear behavior stems from the escape of quasiparticles from the surface bound states into the bulk fluid.

  20. Intrinsic pinning of vorticity by domain walls of l texture in superfluid 3He-A.

    PubMed

    Walmsley, P M; White, I J; Golov, A I

    2004-11-05

    We present the first observation of substantial persistent flow in superfluid 3He-A in thick simply connected slabs in a zero magnetic field, but only in l textures with domain walls. The flow is induced in a rotating cryostat using a torsional oscillator as a probe. The hysteretic dependences of the trapped vorticity on the maximal angular velocity of rotation are fairly universal for different densities of domain walls and slab thicknesses. A model of a critical state set by either the critical velocity for vortex nucleation or pinning strength explains all observations.

  1. Oceanic lavas sampling the high 3He/4He mantle reservoir: Primitive, depleted, or re-enriched?

    NASA Astrophysics Data System (ADS)

    Garapic, G.; Mallik, A.; Dasgupta, R.; Jackson, M. G.

    2014-12-01

    Helium isotopes are used as a tracer for primitive reservoirs that have persisted in the Earth's mantle. Basalts erupted at several intraplate oceanic islands, including Hawaii, Iceland, Galapagos and Samoa, have hosted the highest 3He/4He ratios (> 30 Ra, where Ra is atmospheric 3He/4He ratio) globally that are far in excess of the 3He/4He typical of the upper mantle sampled at mid-ocean ridges (8 Ra). These lavas have been suggested to be melts of a primitive, or possibly slightly depleted, mantle reservoir, i.e., either fertile or a depleted peridotite. We report evidence for geochemical enrichment in the high 3He/4He mantle sampled by lavas with the highest 3He/4He from Hawaii, Samoa and possibly Galapagos. The titanium concentrations in high 3He/4He lavas from Samoa are too high to be explained by melts of a mantle peridotite, even at infinitesimally small degrees of melting, and the elevated Ti corresponds to elevated Pb-isotopic ratios. The highest 3He/4He lavas from Loihi, Hawaii have Ti concentrations that are too high to be melts of primitive mantle peridotite at the degrees of melt extraction proposed for those ocean islands. Thus, Ti-rich material must have been added to the high 3He/4He mantle reservoir, and this material is likely to be recycled mafic crust similar to MORB-like eclogite, which is consistent with the elevated Pb-isotopic ratios. We show that fractionation corrected, major element compositions of high 3He/4He alkalic lavas can be satisfactorily modeled by melting and melt-rock interaction scenario in a fertile peridotite-MORB-eclogite hybrid system. Primitive peridotitic and recycled eclogitic reservoirs are suggested to be intimately associated in the deepest mantle and far from being primitive, the high 3He/4He lavas may sample a mantle source that hosts a component of recycled oceanic crust.

  2. In Vivo Lung Morphometry with Accelerated Hyperpolarized 3He Diffusion MRI: A Preliminary Study

    PubMed Central

    Chang, Yulin V.; Quirk, James D.; Yablonskiy, Dmitriy A.

    2014-01-01

    Purpose Parallel imaging can be used to reduce imaging time and to increase the spatial coverage in hyperpolarized gas MRI of the lung. In this proof-of-concept study we investigate the effects of parallel imaging on the morphometric measurement of lung microstructure using diffusion MRI with hyperpolarized 3He. Methods Fully sampled and under-sampled multi-b diffusion data were acquired from human subjects using an 8-channel 3He receive coil. A parallel imaging reconstruction technique (GRAPPA) was used to reconstruct under-sampled k-space data. The morphometric results of the GRAPPA-reconstructed data were compared with the results of fully sampled data for three types of subjects: healthy volunteers, mild, and moderate COPD patients. Results Morphometric measurements varied only slightly at mild acceleration factors. The results were largely well preserved compared to fully sampled data for different lung conditions. Conclusion Parallel imaging, given sufficient signal-to-noise ratio, provides a reliable means to accelerate hyperpolarized-gas MRI with no significant difference in the measurement of lung morphometry from the fully sampled images. GRAPPA is a promising technique to significantly reduce imaging time and/or to improve the spatial coverage for the morphometric measurement with hyperpolarized gases. PMID:24799044

  3. Lithium glass scintillator neutron detector as an improved alternative to the standard 3 he proportional counter

    SciTech Connect

    Vladimir Popov, Pavel Degtiarenko

    2011-06-01

    Lithium glass scintillator made from 6Li-enriched substrate is a well known for its neutron detection capability. In spite of neutron interaction, cross section of 6Li happens to be lower than that of 3He. However, the neutron detection efficiency could be higher due to higher volume content of 6Li nuclear in the solid scintillator vs. gas filled proportional counter. At the same time, as lithium glass is sensitive to gamma and charge particle radiation, non-neutron radiation discrimination is required. Our detector is composed of two equal-size cylindrical Li(Ce) glass scintillators. The first one is high-sensitive to thermal neutrons GS-20 (6Li doped), the second one is GS-30 (7Li doped) type Scint-Gobain made lithium glass scintillator. Each of scintillators is coupled with R7400U Hamamatsu subminiature photomultiplier tube, and all assembly is fitted into NP100H 3He tube size. 6Li absorbs thermal neutrons releasing alpha particles and triton with 4.8 MeV total energy deposit inside the scintillator (equivalent to about ~1.3 MeV gamma energy depositions). Because 7Li isotope does not absorb thermal neutrons, and the physical properties of the two scintillators are virtually identical, the difference between these two scintillators could be used to provide neutron dose rate information. Results of study of neutron detector assembled of two Li(Ce) scintillators and NP100H moderator are presented

  4. Effects of Diffusion Time on Short-Range Hyperpolarized 3He Diffusivity Measurements in Emphysema

    PubMed Central

    Gierada, David S.; Woods, Jason C.; Bierhals, Andrew J.; Bartel, Seth T.; Ritter, Jon H.; Choong, Cliff K.; Das, Nitin A.; Hong, Cheng; Pilgram, Thomas K.; Chang, Yulin V.; Jacob, Richard E.; Hogg, James C.; Battafarano, Richard J.; Cooper, Joel D.; Meyers, Bryan F.; Patterson, G. Alexander; Yablonskiy, Dmitriy A.; Conradi, Mark S.

    2010-01-01

    Purpose To characterize the effect of diffusion time on short-range hyperpolarized 3He MR diffusion measurements across a wide range of emphysema severity. Materials and Methods 3He diffusion MR imaging was performed on 19 lungs or lobes resected from 18 subjects with varying degrees of emphysema using 3 diffusion times (1.6 msec, 5 msec, and 10 msec) at constant b value. Emphysema severity was quantified as the mean apparent diffusion coefficient (ADC) and as the percentage of pixels with ADC higher than multiple thresholds from 0.30–0.55 cm2/sec (ADC index). Quantitative histology (mean linear intercept) was obtained in 10 of the lung specimens from 10 of the subjects. Results The mean ADCs with diffusion times of 1.6, 5.0, and 10.0 msec were 0.46, 0.40, and 0.37 cm2/sec, respectively (P <0.0001, ANOVA). There was no relationship between the ADC magnitude and the effect of diffusion time on ADC values. Mean linear intercept correlated with ADC (r=0.91–0.94, P<0.001) and ADC index (r=0.78–0.92, P<0.01) at all diffusion times. Conclusion Decreases in ADC with longer diffusion time were unrelated to emphysema severity. The strong correlations between the ADC at all diffusion times tested and quantitative histology demonstrate that the ADC is a robust measure of emphysema. PMID:19787725

  5. High-relief glacial landscape evolution constrained by apatite 4He/3He thermochronometry

    NASA Astrophysics Data System (ADS)

    Shuster, D. L.; Sanders, J. W.; Cuffey, K. M.

    2009-12-01

    Apatite 4He/3He thermochronometry of bedrock samples collected from high-relief and heavily glaciated terrain near Milford Sound in Fiordland, New Zealand reveals clear differences between the cooling histories of high and low elevation samples. Across the region, the youngest apatite (U-Th)/He ages ~1 million years (Ma) generally occur at cirque floor elevations (~500-700 m elevation) rather than at sea level where (U-Th)/He ages approach ~2 Ma. Thermal histories constrained by 4He/3He thermochronometry of three vertically oriented samples collected along the headwall of a ~1100 meter deep cirque indicate that since ~1 Ma ago: (i) rocks presently located near the cirque rim (~1720 m elevation) have resided at temperatures <25 oC, while (ii) rocks at the floor of the cirque (~575 m elevation) continuously cooled from ~75-110 oC to the present surface temperature. These thermal histories indicate that most of the cirque relief developed over the last ~1 Ma and/or the sub-surface thermal field was highly perturbed during that time interval over an ~1 km horizontal scale. We will interpret sample cooling histories in conjunction with a 3-D model of subsurface temperature evolution in response to changes in topography. The goal is to constrain the rates and patterns of glacial valley development over the Quaternary.

  6. Exploiting intrinsic triangular geometry in relativistic (3)He+Au collisions to disentangle medium properties.

    PubMed

    Nagle, J L; Adare, A; Beckman, S; Koblesky, T; Koop, J Orjuela; McGlinchey, D; Romatschke, P; Carlson, J; Lynn, J E; McCumber, M

    2014-09-12

    Recent results in d+Au and p+Pb collisions at RHIC and the LHC provide evidence for collective expansion and flow of the created medium. We propose a control set of experiments to directly compare particle emission patterns from p+Pb, d+Au, and ^{3}He+Au or t+Au collisions at the same sqrt[s_{NN}] . Using a Monte Carlo Glauber simulation we find that a ^{3}He or triton projectile, with a realistic wave function description, induces a significant intrinsic triangular shape to the initial medium. If the system lives long enough, this survives into a significant third-order flow moment v_{3} even with viscous damping. By comparing systems with one, two, and three initial hot spots, one could disentangle the effects from the initial spatial distribution of the deposited energy and viscous damping. These are key tools for answering the question of how small a droplet of matter is necessary to form a quark-gluon plasma described by nearly inviscid hydrodynamics.

  7. Effects of Diffusion Time on Short-Range Hyperpolarized 3He Diffusivity Measurements in Emphysema

    SciTech Connect

    Gierada, David S.; Woods, Jason C.; Bierhals, Andrew J.; Bartel, Seth T.; Ritter, Jon H.; Choong, Cliff K.; Das, Nitin A.; Hong, Cheng; Pilgram, Thomas K.; Chang, Yulin V.; Jacob, Rick E.; Hogg, James C.; Battafarano, Richard J.; Cooper, Joel D.; Meyers, Bryan F.; Patterson, G Alexander; Yablonskiy, Dmitriy A.; Conradi, Mark S.

    2009-09-28

    Purpose: To characterize the effect of diffusion time on short-range hyperpolarized 3He MR diffusion measurements across a wide range of emphysema severity. Materials and Methods: 3He diffusion MR imaging was performed on 19 lungs or lobes resected from 18 subjects with varying degrees of emphysema using 3 diffusion times (1.6 msec, 5 msec, and 10 msec) at constant b value. Emphysema severity was quantified as the mean apparent diffusion coefficient (ADC) and as the percentage of pixels with ADC higher than multiple thresholds from 0.30-0.55 cm2/sec (ADC index). Quantitative histology (mean linear intercept) was obtained in 10 of the lung specimens from 10 of the subjects. Results: The mean ADCs with diffusion times of 1.6, 5.0, and 10.0 msec were 0.46, 0.40, and 0.37 cm2/sec, respectively (P <0.0001, ANOVA). There was no relationship between the ADC magnitude and the effect of diffusion time on ADC values. Mean linear intercept correlated with ADC (r=0.91-0.94, P<0.001) and ADC index (r=0.78-0.92, P<0.01) at all diffusion times.

  8. Simulation of ion chamber signals in the n+3 He -> p + t experiment

    NASA Astrophysics Data System (ADS)

    Coppola, Christopher; n3He Collaboration

    2017-01-01

    The parity violating proton directional asymmetry from the capture of polarized neutrons on 3He was 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 0.476 atmosphere. Signal wires in the chamber have different sensitivities to the physics asymmetry, depdendent on their location and the configuration of the experiment. These geometry factors must be determined by simulation. In addition, simulation estimates the statistical precision of the experiment, optimizes configuration variables, and assists with systematic 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 phsyics inputs to the simulation came from measurements of the neutron phase space, ENDF cross sections, and PSTAR ionization data. A cell model was applied 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.

  9. On chiral magnetic effect in Weyl superfluid 3He-A

    NASA Astrophysics Data System (ADS)

    Volovik, G. E.

    2017-01-01

    In the theory of the chiral anomaly in relativistic quantum field theories (RQFT) some results depend on regularization scheme at ultraviolet. In the chiral superfluid 3He-A, which contains two Weyl points and also experiences the effects of chiral anomaly, the "trans-Planckian" physics is known and the results can be obtained without regularization. We discuss this on example of the chiral magnetic effect (CME), which has been observed in 3He-A in 90's [1]. There are two forms of the contribution of the CME to the Chern-Simons term in free energy, perturbative and non-perturbative. The perturbative term comes from the fermions living in the vicinity of the Weyl point, where the fermions are "relativistic" and obey the Weyl equation. The non-perturbative term originates from the deep vacuum, being determined by the separation of the two Weyl points in momentum space. Both terms are obtained using the Adler-Bell-Jackiw equation for chiral anomaly, and both agree with the results of the microscopic calculations in the "trans-Planckian" region. Existence of the two nonequivalent forms of the Chern-Simons term demonstrates that the results obtained within the RQFT depend on the specific properties of the underlying quantum vacuum and may reflect different physical phenomena in the same vacuum.

  10. Homogeneous 3 He- 4 He solid solutions in the pre-separation region

    NASA Astrophysics Data System (ADS)

    Antsygina, T. N.; Lisunov, A. A.; Maidanov, V. A.; Rubanskyi, V. Y.; Rubets, S. P.; Rudavskii, E. Ya.; Chishko, K. A.

    2011-10-01

    Temperature dependences of the pressure P( T) in homogeneous solid 3He- 4He mixtures have been studied experimentally in the wide range of concentrations (35.0%, 62.0%, 68.3%, 74.1%, 75.0%, and 89.3% 3He) above and below the equilibrium phase separation temperature Ts. An anomalous behaviour of the pressure in the vicinity of Ts is found for all investigated samples. With decreasing temperature, as Ts is approached, the pressure increases instead of expected reduction due to decrease in the phonon contribution ( Pph∼T4). Such an increase in pressure continues in the metastable region below Ts until the mixture separates. Theoretical interpretation of the observed effects based on a rigorous thermodynamic approach is proposed. The found experimentally pressure behaviour can be described only with the consistent account for fluctuations in the impurity subsystem which near Ts dominates over phonon contribution into the pressure. The obtained theoretical results are in good quantitative agreement with the experimental data. Density fluctuations in the concentrated mixtures give rise to a spontaneous formation of impuriton nano-clusters containing several hundreds of atoms. The fluctuation can be rigorously interpreted as a nucleus of the second phase in the pre-separated homogeneous solid mixture. The estimated size of the fluctuation nano-clusters agrees with the corresponding value for second phase nuclei obtained from the Lifshits-Slesov phenomenological theory of homogeneous nucleation.

  11. A new Holocene eruptive history of Erebus volcano, Antarctica using cosmogenic 3He and 36Cl

    NASA Astrophysics Data System (ADS)

    Parmelee, D. E.; Kyle, P. R.; Kurz, M. D.; Marrero, S.

    2013-12-01

    Unraveling the timing of a volcano's most recent eruptions is crucial to understanding its present and future behavior. In this study, we use cosmogenic 3He and 36Cl in mineral separates (clinopyroxene and anorthoclase, respectively) to date the 10 most recent lava flows on Erebus volcano. Erebus is a 2,170-km3 active stratovolcano on Ross Island, Antarctica that is known for its persistent anorthoclase phonolite lava lake and frequent Strombolian eruptions. Previous anorthoclase 40Ar/39Ar ages from the 10 flows [1, 2] suggest they were erupted at roughly regular intervals between 17 and 0 ka. However, the uncertainties on the Ar ages are large (up to 39 %), and the likelihood of excess 40Ar in melt inclusions may skew the Ar ages older than eruption ages. The new cosmogenic ages provide new insights into Erebus eruption chronology. We used two different models to scale production rates: the Lal/Stone model [3] and the new Sato/Lifton model [4]. We find ~20-25 % younger ages with the Sato/Lifton model, attributable to different treatment of atmospheric pressure effects, solar modulation effects, and muogenic production rates in each model. 3He and 36Cl exposure ages of the same 10 flows range from 4.5 × 0.1 to 9.7 × 0.2 ka (Lal/Stone) or 3.5 × 0.1 to 7.5 × 0.2 ka (Sato/Lifton), significantly different than the Ar ages, with a much shorter eruption period. Surprisingly, three of the flows have exposure ages older than their Ar ages, despite the exposure ages being considered minimum ages of eruption and the Ar ages maxima. Concordance of the 3He and 36Cl ages measured in the same samples strengthens the validity of our results and implies that the 3He and 36Cl production rates [5] are well-calibrated for high latitude, high altitude sites and that the methodologies are robust. Regardless of which scaling model is used, the results yield a new understanding of the current eruptive phase of Erebus, particularly in documenting the short timespan over which the

  12. Momentum and spin transport properties of spin polarized Fermi systems

    NASA Astrophysics Data System (ADS)

    Wei, Lijuan

    We carried out experiments on a spin polarized 3He- 4He mixture with 3He concentration x 3 = 6.26 x 10-4, and on pure 3He liquid. Spin polarization affects the transport properties of these Fermi systems. The effect on momentum transport was studied by using a vibrating-wire viscometer to measure viscosity of the 3He-4He mixture over the temperature range 6.09 mK--100 mK in 7.96 T and 1.00 T magnetic fields. A large viscosity increase was observed upon application of the 7.96 T magnetic field for temperature T < TF(TF = 19.5 mK is the Fermi temperature). The observed viscosity is in very good agreement with theoretical calculations for a dilute Fermi gas by Jeon and Mullin [1988, 1989] and Mullin and Jeon [1992]. The polarization effect on spin transport was investigated by measuring the transverse diffusion coefficient D ⊥ in pure 3He liquid at saturated vapor pressure and at 15.85 bar over the temperature range 4.5 mK--159 mK in a 7.96 T magnetic field. We used a pulsed NMR spin echo technique in a field gradient of 16.0 G/cm to do the measurements and fits to the Leggett equations [1970] to obtain D⊥. For T < 20 mK, we found D⊥ is less than measured in earlier experiments at lower magnetic fields. D⊥ does not increase with decreasing temperature as 1/T2, but appears to approach a constant as T → 0 while it is expected that the longitudinal spin diffusion coefficient D∥ ∝ 1/ T2. This is called spin diffusion anisotropy and it was observed for the first time in our 3He liquid experiments. The anisotropy temperature we determined for 3He liquid was Ta = 16.4 +/- 2.2 mK at saturated vapor pressure and in a 7.96 T magnetic field. The transverse spin diffusion in 3 He results agree qualitatively with theories proposed by Meyerovich and Musaeflan [1992, 1994]. They also agree qualitatively with theories proposed by Golosov and Ruckenstein [1995, 1998] by extrapolation of the dilute theory to a strongly interacting system.

  13. Realization of the 3He Vapor-Pressure Temperature Scale and Development of a Liquid-He-Free Calibration Apparatus

    NASA Astrophysics Data System (ADS)

    Shimazaki, T.; Toyoda, K.; Tamura, O.

    2011-12-01

    The 3He vapor-pressure temperature scale was realized using an apparatus based on a continuously operating 3He cryostat at the National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST). The cryostat has two operational modes: a 3He circulation mode and a 1 K pot mode. The 3He circulation mode can be used for 3He vapor-pressure measurements below 1.6 K, and the 1 K pot mode can be used for measurements above 1.3 K. Either mode can be selected for measurements from 1.3 K to 1.6 K. The realization of the 3He vapor-pressure temperature scale in this study fully covers its defined temperature range from 0.65 K to 3.2 K in the International Temperature Scale of 1990. The latest realization results are presented in this article. In addition, a liquid-He-free calibration apparatus was developed. It does not require liquid helium as a cryogen, which usually entails cumbersome handling and periodic refilling. The apparatus was designed for the calibration of capsule-type resistance thermometers from 0.65 K to 24.5561 K (the triple point of neon). The cooling system of the apparatus consists of a commercially available pulse-tube refrigerator and a 3He Joule-Thomson (JT) cooling circuit developed at NMIJ/AIST. The pulse-tube refrigerator is used in a pre-cooling stage and cools the apparatus to approximately 5 K. The 3He JT cooling circuit is used to cool the apparatus from 5 K to below 0.65 K. Since the 3He JT cooling circuit is a closed circuit, the apparatus can run continuously with only simple maintenance required. The basic characteristics of the apparatus are described.

  14. Stability of vortex lines in liquid {sup 3}He-{sup 4}He mixtures at zero temperature

    SciTech Connect

    Jezek, D.M.; Guilleumas, M.; Pi, M.; Barranco, M.

    1997-05-01

    At low temperatures and {sup 3}He concentrations below {approximately}6.6{percent}, there is experimental evidence about the existence in liquid helium mixtures of stable vortices with {sup 3}He-rich cores. When the system is either supersaturated or submitted to a tensile strength, vortices lose stability becoming metastable and eventually completely unstable, so that their cores freely expand. Within a density functional approach, we have determined the pressure-{sup 3}He concentration curve along which this instability appears at zero temperature. {copyright} {ital 1997} {ital The American Physical Society}

  15. Attenuation of second sound in superfluid 3He-A1

    PubMed

    Sato; Coleman; de Vegvar PG; Kojima; Okuda

    2000-02-14

    The attenuation of second sound (spin-entropy) wave in the superfluid A1 phase has been measured in magnetic fields up to 11 T and to sufficiently high frequency to observe the bulk attenuation proportional to the square of frequency. The measured attenuation coefficient is compared with the existing theories of hydrodynamics and dissipative coefficients. The resulting "excess" attenuation is discussed in terms of the temperature dependent spin diffusion coefficient in the superfluid.

  16. Status Summary of 3He and Neutron Detection Alternatives for Homeland Security

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.

    2010-04-28

    This is a short summary whitepaper on results of our alternatives work: Neutron detection is an important aspect of interdiction of radiological threats for homeland security purposes since plutonium, a material used for nuclear weapons, is a significant source of fission neutrons [Kouzes 2005]. Because of the imminent shortage of 3He, which is used in the most commonly deployed neutron detectors, a replacement technology for neutron detection is required for most detection systems in the very near future [Kouzes 2009a]. For homeland security applications, neutron false alarms from a detector can result in significant impact. This puts a strong requirement on any neutron detection technology not to generate false neutron counts in the presence of a large gamma ray-only source [Kouzes et al. 2008].

  17. A two-stage 3He- 4He fridge for bolometric photometry

    NASA Astrophysics Data System (ADS)

    Maiani, T.; de Bernardis, P.; De Petris, M.; Granata, S.; Masi, S.; Orlando, A.; Aquilini, E.; Cardoni, P.; Martinis, L.; Scaramuzzi, F.

    1999-09-01

    We describe the design, construction and performance of a double stage 3He- 4He refrigerator, built to cool down a multiband bolometric photometer at the MITO telescope. The fridge was optimized to work without external pumps, with the main cryostat providing a 4.2 K thermostat at sea level and a 4.0 K one at high mountain pressure conditions. The measured ultimate temperature of the fridge is 290 mK, with a hold time of 81 h. The external heat input on the cold flange is ˜35 μW, with the main bath at 4.0 K. The recycle time is 8 h with a heat input on the thermostat during recycling of ˜6800 J. The cryostat can operate without any relevant changes to performance tilted down to 50° from the vertical position, as needed at the telescope focal plane.

  18. Stellar and primordial nucleosynthesis of 7Be: measurement of 3He(alpha,gamma)7Be.

    PubMed

    Di Leva, A; Gialanella, L; Kunz, R; Rogalla, D; Schürmann, D; Strieder, F; De Cesare, M; De Cesare, N; D'Onofrio, A; Fülöp, Z; Gyürky, G; Imbriani, G; Mangano, G; Ordine, A; Roca, V; Rolfs, C; Romano, M; Somorjai, E; Terrasi, F

    2009-06-12

    The 3He(alpha,gamma)7Be reaction presently represents the largest nuclear uncertainty in the predicted solar neutrino flux and has important implications on the big bang nucleosynthesis, i.e., the production of primordial 7Li. We present here the results of an experiment using the recoil separator ERNA (European Recoil separator for Nuclear Astrophysics) to detect directly the 7Be ejectiles. In addition, off-beam activation and coincidence gamma-ray measurements were performed at selected energies. At energies above 1 MeV a large discrepancy compared to previous results is observed both in the absolute value and in the energy dependence of the cross section. Based on the available data and models, a robust estimate of the cross section at the astrophysical relevant energies is proposed.

  19. Accurate optical measurement of nuclear polarization in optically pumped ^3He gas

    NASA Astrophysics Data System (ADS)

    Bigelow, N. P.; Nacher, P. J.; Leduc, M.

    1992-12-01

    Large nuclear polarizations M (over 80 %) can now be achieved in gaseous ^3He by optical pumping. The gas is excited by an RF discharge and is oriented using a high power LNA laser which is lamp pumped and tuned to the 2 ^3S-2 ^3P transition at 1.08 μm. In this paper we describe an experiment in which we measure M with high absolute precision. Our method is based on a change as a function of M in the ratio of σ or π polarized light absorbed from a weak probe beam by the 2 ^3S metastable atoms. The probe was delivered by a diode pumped LNA laser and propagated perpendicular to the direction of the magnetization. Simultaneous measurement of M was made by monitoring the degree of circular polarization \\cal{P} of the optical line at 668 nm emitted by the discharge. Our measurements show a linear relationship between M and \\cal{P} for all accessible M values and for a wide range of experimental conditions (sample pressure, magnetic field, RF discharge level, etc.). This provides a second method of measurement of the ^3He nuclear polarization which is simple to operate and is calibrated and is calibrated over a pressure range of 0.15 to 6.5 torr. On peut maintenant produire par pompage optique de fortes polarisations nucléaires M (M supérieure à 80 % dans l' ^3He gazeux. Le gaz est excité par une décharge radiofréquence et orienté à l'aide d'un laser LNA de forte intensité qui est pompé par des lampes et accordé sur la transition 2 ^3S-2 ^3P à 1,08 μm. Dans cet article, nous décrivons une expérience où nous mesurons M avec une grande précision absolue. Notre méthode est fondée sur la variation en fonction de M de l'absorption par les atomes métastables d'un faisceau sonde de faible intensité polarisé linéairement. Nous mesurons le rapport des absorptions pour des polarisations π et σ. Le faisceau sonde est un laser LNA pompé par diode qui se propage perpendiculairement à la direction de l'aimantation. Simultanément, nous mesurons M par le

  20. Rapid glacial erosion at 1.8 Ma revealed by 4He/3He thermochronometry.

    PubMed

    Shuster, David L; Ehlers, Todd A; Rusmoren, Margaret E; Farley, Kenneth A

    2005-12-09

    Alpine glaciation and river incision control the topography of mountain ranges, but their relative contributions have been debated for years. Apatite 4He/3He thermochronometry tightly constrains the timing and rate of glacial erosion within one of the largest valleys in the southern Coast Mountains of British Columbia, Canada. Five proximate samples require accelerated denudation of the Klinaklini Valley initiating 1.8 +/- 0.2 million years ago (Ma). At least 2 kilometers of overlying rock were removed from the valley at >/=5 millimeters per year, indicating that glacial valley deepening proceeded >/=6 times as fast as erosion rates before approximately 1.8 Ma. This intense erosion may be related to a global transition to enhanced climate instability approximately 1.9 Ma.

  1. Construction of a 3He magnetic force microscope with a vector magnet

    NASA Astrophysics Data System (ADS)

    Yang, Jinho; Yang, Ilkyu; Kim, Yun Won; Shin, Dongwoo; Jeong, Juyoung; Wulferding, Dirk; Yeom, Han Woong; Kim, Jeehoon

    2016-02-01

    We constructed a 3He magnetic force microscope operating at the base temperature of 300 mK under a vector magnetic field of 2-2-9 T in the x-y-z direction. Fiber optic interferometry as a detection scheme is employed in which two home-built fiber walkers are used for the alignment between the cantilever and the optical fiber. The noise level of the laser interferometer is close to its thermodynamic limit. The capabilities of the sub-Kelvin and vector field are demonstrated by imaging the coexistence of magnetism and superconductivity in a ferromagnetic superconductor (ErNi2B2C) at T = 500 mK and by probing a dipole shape of a single Abrikosov vortex with an in-plane tip magnetization.

  2. Stationary convection in dilute solutions of 3He in superfluid 4He

    PubMed Central

    Warkentin, P. A.; Haucke, H. J.; Lucas, P.; Wheatley, J. C.

    1980-01-01

    Two symmetric, convecting steady states have been observed in a novel cell of unity aspect ratio and studied over a range of temperature for two concentrations of 3He in superfluid 4He. An existing theory due to Parshin has been related to the conditions necessary for convection in this system, defining a Rayleigh number closely analogous to that of a classical one-component Bénard system. Values of this Rayleigh number at the onset of convection calculated from experimental data are found to have little temperature dependence, with an average value near that for a classical one-component fluid in this geometry. The Prandtl number is small and temperature dependent, with a smallest calculated value of 0.05. PMID:16592932

  3. NN correlations measured in 3He(e, e'pp)n

    SciTech Connect

    Lawrence Weinstein; Rustam Niyazov

    2003-07-15

    We have measured the 3He (e, e'pp)n reaction in the Jefferson Lab CLAS with 2.2 and 4.4 GeV electrons. We looked at the energy distribution of events with all three nucleons at high momentum (p > 250 MeV/c). This distribution has peaks where two nucleons each have 20% or less of the energy transfer (i.e., the third or ?leading? nucleon carries most of the kinetic energy). The angular distribution of these two ?fast? nucleons shows a very large back-to-back peak, indicating the effect of correlations. While there is some theoretical disagreement, experimental evidence, plus calculations at lower energy by W. Gloeckle, indicates that these events are primarily sensitive to NN correlations.

  4. Considerations on the read out of low frequency NMR for 3He

    NASA Astrophysics Data System (ADS)

    Benningshof, O. W. B.; Nguyen, D. H.; Jochemsen, R.

    2009-02-01

    For studies of the superfmid phases of 3He the technique low of frequency (500 kHz) NMR is widely used. One way to read out the NMR signal is with the continuous wave experiment. In this experiment the NMR signal is proportional with the quality factor of a tank circuit. However direct connection with a coax cable will, because of its resistivity and parasitic capacitance load the tank circuit and by that lower the quality factor In this paper two passive methods, which minimize the loading to read out the NMR signal are described and simulated. The first method reads the NMR signal over the parasitic capacitance of the coax cable, which is put in series with the tank circuit. The second method makes use of a pick up coil, which is weakly coupled to the coil of the tank circuit Both methods can preserve a high quality factor, and are optimized for best SNR

  5. Polarized 3He target and Final State Interactions in SiDIS

    DOE PAGES

    Del Dotto, Alessio; Kaptari, Leonid; Pace, Emanuele; ...

    2017-01-03

    Jefferson Lab is starting a wide experimental program aimed at studying the neutron’s structure, with a great emphasis on the extraction of the parton transverse-momentum distributions (TMDs). To this end, Semi-inclusive deep-inelastic scattering (SiDIS) experiments on polarized $^3$He will be carried out, providing, together with proton and deuteron data, a sound flavor decomposition of the TMDs. Here, given the expected high statistical accuracy, it is crucial to disentangle nuclear and partonic degrees of freedom to get an accurate theoretical description of both initial and final states. In this contribution, a preliminary study of the Final State Interaction (FSI) in themore » standard SiDIS, where a pion (or a Kaon) is detected in the final state is presented, in view of constructing a realistic description of the nuclear initial and final states.« less

  6. Tensor Correlations Measured in 3He(e,e'pp)n

    SciTech Connect

    Baghdasaryan, H; Weinstein, L B; Adhikari, K P; Aghasyan, K P; Amarian, M; Anghinolfi, M; Avakian, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Berman, B L; Biselli, A S; Bookwalter, C; Briscoe, W J; Brooks, W K; Boltmann, S; Burkert, V D; Carman, D S; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; DeVita, R; DeSanctis, E; Deur, A; Dey, B; Dickson, R; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Eugenio, P; Fegan, S; Gabrielyan, M Y; Gilfoyle, G P; Giovanetti, K L; Gohn, W; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Gyurjyan, V; Hakobyan, H; Hanretty, C; Hyde, C E; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, A; Klein, F J; Konczykowski, P; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I.J.D.; Markov, N; Mayer, M; McAndrew, J; McKinnon, B; Meyer, C A; Mikhailov, K; Mokeev, V; Moreno, B; Moriya, K; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nepali, C; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Anefalos Pereira, S; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Sabatie, F; Salgado, C; Schumacher, R A; Seraydaryan, H; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tedeschi, D J; Ungaro, M; Vineyard, M F; Voutier, E; Watts, D P; Weygand, D P; Wood, M H; Zhao, B; Zhao, Z W

    2010-11-01

    We have measured the 3He(e,e'pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum ptot. For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low ptot and rises to approximately 0.5 at large ptot. This shows the dominance of tensor over central correlations at this relative momentum.

  7. Ocean Circulation and Mixing: New Insights From the Global Distribution of 3He

    NASA Astrophysics Data System (ADS)

    Schlosser, P.; Newton, R.; Winckler, G.

    2007-05-01

    Since the discovery of mantle 3He in the ocean in the 1960's by Clarke and others this isotope has been used in numerous studies of ocean circulation and mixing. Recently, a global helium isotope data set has been collected during the World Ocean Circulation Experiment (WOCE). We combined the WOCE helium isotope data with similar, but smaller, data sets from previous global and regional studies such as GEOCSECS or TTO to study features of the global ocean circulation, as well as ventilation and mixing. In this contribution we describe the global data set and discuss the first results obtained on global ocean ventilation and deep ocean mixing. A simple model is used to estimate vertical turbulent exchange coefficients for the deep ocean in the South Pacific and the results are compared to mixing coefficients obtained from fine structure measurements and tracer release experiments.

  8. MR Imaging of Apparent 3He Gas Transport in Narrow Pipes and Rodent Airways

    SciTech Connect

    Minard, Kevin R.; Jacob, Rick E.; Laicher, Gernot; Einstein, Daniel R.; Kuprat, Andrew P.; Corley, Richard A.

    2008-10-01

    High sensitivity makes hyperpolarized 3He an attractive signal source for visualizing gas flow with magnetic resonance (MR) imaging. Its rapid Brownian motion, however, can blur observed flow lamina and alter measured diffusion rates when excited nuclei traverse shear-induced velocity gradients during data acquisition. Here, both effects are described analytically, and predicted values for measured transport during laminar flow through a straight, 3.2-mm-diameter pipe are validated using two-dimensional (2D) constant-time images of different binary gas mixtures. Results show explicitly how measured transport in narrow conduits is characterized by apparent values that depend on underlying gas dynamics and imaging time. In ventilated rats, this is found to obscure acquired airflow images. Flow splitting at airway branches is still evident, however, and use of 3D vector flow mapping is shown to provide a quantitative view of pulmonary gas supply that highlights the correlation of airflow dynamics with lung structure.

  9. The Mirror Nuclei 3H and 3He Program at JLab

    NASA Astrophysics Data System (ADS)

    Gomez, Javier

    2017-03-01

    Using electron beam energies of up to 11 GeV, Jefferson Lab plans to carry out in the near future a group of four experiments involving the mirror nuclei 3H and 3He. The experiments aim to, (A) extract the deep inelastic neutron to proton structure function ratio F_2^n/F_2^p (and u / d quark distributions) for 0.2 ≤ x ≤ 0.9, (B) study the isospin structure of two-nucleon and search for three-nucleon Short Range Correlations (SRC) for x < 3, (C) measure the proton momentum distribution of both nuclei at x = 1.2 to further our understanding of SRCs in the few-body and (D) extract the charge radii of both nuclei at Q^2 ≤ 0.1 GeV^2.

  10. {sup 3}He melting pressure temperature scale below 25 mK

    SciTech Connect

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

    1995-04-01

    Using {sup 60}Co {gamma} ray anisotropy radiation as a primary thermometer, with a Pt NMR susceptibility secondary thermometer, the authors have made high precision measurements of the {sup 3}He melting pressure versus temperature from 500 {mu}K to 25 mK. Temperatures obtained 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. The authors provide a functional form for P(T), which, with the fixed points, constitutes a convenient temperature scale, based on a primary thermometer, usable to well below 1 mK.

  11. Polarized ^{\\varvec{3}}He Target and Final State Interactions in SiDIS

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Jefferson Lab is starting a wide experimental program aimed at studying the neutron's structure, with a great emphasis on the extraction of the parton transverse-momentum distributions (TMDs). To this end, Semi-inclusive deep-inelastic scattering (SiDIS) experiments on polarized ^3He will be carried out, providing, together with proton and deuteron data, a sound flavor decomposition of the TMDs. Given the expected high statistical accuracy, it is crucial to disentangle nuclear and partonic degrees of freedom to get an accurate theoretical description of both initial and final states. In this contribution, a preliminary study of the Final State Interaction (FSI) in the standard SiDIS, where a pion (or a Kaon) is detected in the final state is presented, in view of constructing a realistic description of the nuclear initial and final states.

  12. Anomalous Resonance Frequency Shift of a Microelectromechanical Oscillator in Superfluid ^3 He-B

    NASA Astrophysics Data System (ADS)

    Zheng, P.; Jiang, W. G.; Barquist, C. S.; Lee, Y.; Chan, H. B.

    2017-02-01

    A superfluid ^3 He film with a thickness of 1.25 μm was studied using a microelectromechanical oscillator at various pressures of 9.2, 18.2, 25.2, and 28.6 bars. The oscillator was driven in the linear damping regime where the damping coefficient is independent of the velocity of the oscillator. The resonance frequency shows weak temperature and pressure dependences in the low temperature limit. An inertia coefficient of ≈ 0.1 was obtained in the ballistic regime. When the temperature rose from the lowest temperature, the resonance frequency of the resonator exhibited an unusual behavior, a rapid increase beyond the intrinsic value as temperature increases, for 9.2 and 18.2 bars.

  13. A 3He gas heat switch for the 0.5-2 K temperature range

    NASA Astrophysics Data System (ADS)

    Smith, Eric N.; Parpia, Jeevak M.; Beamish, John R.

    2000-07-01

    We have constructed a prototype heat switch for use in a cyclic demagnetization apparatus. The desired operating range of the switch is from 0.5 to 1.8 K. The measured conductivity of the switch is 50 μW/ K at 1.5 K when ‘off ’ and 8 mW/K at 0.5 K when ‘on’. The switching is carried out by 3He gas which is admitted and extracted from the device by a miniature charcoal adsorption pump which is controlled by electrical heat and a weak thermal link to a pumped 4He bath. In this paper we discuss details of construction and the performance as a function of temperature, and consider the switching time between on and off states.

  14. The Mirror Nuclei 3H and 3He Program at JLab

    DOE PAGES

    Gomez, Javier

    2017-02-28

    Jefferson Lab plans to carry out in the near future a group of four experiments involving the mirror nuclei 3H and 3He, using electron beam energies of up to 11 GeV. Our experiments aim to, (A) extract the deep inelastic neutron to proton structure function ratio Fmore » $$n\\atop{2}$$F$$p\\atop{2}$$ (and u / d quark distributions) for 0.2 ≤ x ≤ 0.9 , (B) study the isospin structure of two-nucleon and search for three-nucleon Short Range Correlations (SRC) for x < 3 , (C) measure the proton momentum distribution of both nuclei at $x = 1.2$ to further our understanding of SRCs in the few-body and (D) extract the charge radii of both nuclei at Q2 ≤ 0.1 GeV2.« less

  15. Relaxation dynamics of spindodal decomposition in superfluid ^3He-^4He mixtures

    NASA Astrophysics Data System (ADS)

    Chay, Terrence Y.; Goldenfeld, Nigel; Bauer, Gregory H.; Ceperley, David M.

    1998-03-01

    We study the dynamics of the Hohenberg-Nelson system(P.C. Hohenberg and David R. Halperin, Phys. Rev. B 20):2665 (1979). for ^3He-^4He mixtures after a quench using a mesoscopic cell dynamical systems (CDS) model. The spinodal region is characterized by maximal growth at a single nonzero wave vector which scales with time. Because CDS exploits universality to avoid taking Δ x and Δ t to infinitesimals, rapid simulations are possible on large systems making it an ideal way to find such scaling behavior. Using thermodynamic properties obtained from experiement and exactly calculated from path integral monte carlo studies, one can obtain the workable CDS phenomenological parameters to do time evolution studies of large-scale mixtures.

  16. The parity-violating asymmetry in the 3He(n,p)3H reaction

    SciTech Connect

    M. Viviani, R. Schiavilla, L. Girlanda, A. Kievsky, L.E. Marcucci

    2010-10-01

    The longitudinal asymmetry induced by parity-violating (PV) components in the nucleon-nucleon potential is studied in the charge-exchange reaction 3He(n,p)3H at vanishing incident neutron energies. An expression for the PV observable is derived in terms of T-matrix elements for transitions from the {2S+1}L_J=1S_0 and 3S_1 states in the incoming n-3He channel to states with J=0 and 1 in the outgoing p-3H channel. The T-matrix elements involving PV transitions are obtained in first-order perturbation theory in the hadronic weak-interaction potential, while those connecting states of the same parity are derived from solutions of the strong-interaction Hamiltonian with the hyperspherical-harmonics method. The coupled-channel nature of the scattering problem is fully accounted for. Results are obtained corresponding to realistic or chiral two- and three-nucleon strong-interaction potentials in combination with either the DDH or pionless EFT model for the weak-interaction potential. The asymmetries, predicted with PV pion and vector-meson coupling constants corresponding (essentially) to the DDH "best values" set, range from -9.44 to -2.48 in units of 10^{-8}, depending on the input strong-interaction Hamiltonian. This large model dependence is a consequence of cancellations between long-range (pion) and short-range (vector-meson) contributions, and is of course sensitive to the assumed values for the PV coupling constants.

  17. High performance manned interplanetary space vehicle using D-3He Inertial Electrostatic Fusion

    NASA Astrophysics Data System (ADS)

    Burton, R.; Momota, H.; Richardson, N.; Coventry, M.; Shaban, Y.; Miley, G. H.

    2002-01-01

    A preliminary system design is presented for a high performance 100 MWe manned space vehicle in the 500 metric ton class, based on Inertial Electrostatic Fusion (IEC), with trip times to the outer planets of several months. An IEC is chosen because it simplifies structure results in a very high power to weight ratio. The fusion reactor uses D-3He fuel which generates 14.7-MeV protons as the primary reaction product. The propulsion system design philosophy is based on direct conversion of proton energy to electricity, avoiding the thermalization of the working fluid to maximize efficiency. The principle system components of crew compartment, electronics, fusion reactor, traveling wave direct energy converter, step-down transformer, rectifier, ion thruster and heat rejection radiators are described. The design requires that an IEC reactor with a proton energy gain (power in 14.7-MeV protons/input electric power) of 4 or better is necessary to keep radiator mass and size at acceptable levels. Extrapolation of present laboratory scale IEC experiments to reactor relevant conditions is possible theoretically, but faces several open issues including stability under high-density conditions. Since unburned fusion fuels are recycled rather than exhausted with the propellant, problems of fuel weight and preservation of 3He are minimized. The 100-MWe propulsion system is based on NSTAR-extrapolated krypton ion thrusters operating at a specific impulse of 16,000 seconds and a total thrust of 1020 N. Thrust time for a typical outer planet mission ΔV of 50,000 m/s is then ~200 days. .

  18. In-beam γ-ray Spectroscopy of {sup 30}P via the {sup 28}Si({sup 3}He,pγ){sup 30}P Reaction

    SciTech Connect

    Mcneice, E.; Setoodehnia, K.; Singh, B.; Abe, Y.; Binh, D.N.; Chen, A.A.; Chen, J.; Cherubini, S.; Fukuoka, S.; Hashimoto, T.; Hayakawa, T.; Ishibashi, Y.; Ito, Y.; Kahl, D.; Komatsubara, T.; Kubono, S.; Moriguchi, T.; Nagae, D.; Nishikiori, R.; Niwa, T.; and others

    2014-06-15

    The level structure of {sup 30}P up to 8.25 MeV was investigated via in-beam γ-ray spectroscopy using the {sup 28}Si({sup 3}He,pγ){sup 30}P reaction at 9 MeV at the University of Tsukuba Tandem Accelerator Complex in Japan. An energy level scheme was deduced from γ-γ coincidence measurements. 47 new transitions have been observed from the previously known states (mostly resonances), thereby reducing the uncertainties in the excitation energies of 17 states from 3 to 10 keV to values of < 1 keV. Furthermore, spin assignments based on measurements of γ-ray angular distributions and γ-γ directional correlation of oriented nuclei (DCO ratios) were made for several observed levels of {sup 30}P.

  19. Tritium/3He dating of river infiltration: an example from the Danube in the Szigetkoz Area, Hungary

    USGS Publications Warehouse

    Stute, M.; Deak, J.; Revesz, K.; Böhlke, J.K.; Deseo, E.; Weppernig, R.; Schlosser, P.

    1997-01-01

    3H, 3He, 4He, and Ne data were obtained from a shallow ground-water system being recharged by bank infiltration from the Danube River in northwestern Hungary. After correting for excess air, 4He and Ne concentrations reflect a recharge temperature of about 9?? C, close to the mean annual temperature of the Danube (10.4?? C). Values of 3H plus 3Hetrit, ("initial tritium") as a function of the tritium/3He age are consistent with time series measurements of tritium in the Danube. Tritium/3He ages increase linearly as a function of distance from the Danube along ground-water flow lines. A horizontal flow velocity of about 530 m yr-1 was derived from the age gradient. Most of the deviations between measured Danube tritium data and ground-water tritium/3He data can be explained by dispersive mixing.

  20. Objective estimates of mantle 3He in the ocean and implications for constraining the deep ocean circulation

    NASA Astrophysics Data System (ADS)

    Holzer, Mark; DeVries, Timothy; Bianchi, Daniele; Newton, Robert; Schlosser, Peter; Winckler, Gisela

    2017-01-01

    Hydrothermal vents along the ocean's tectonic ridge systems inject superheated water and large amounts of dissolved metals that impact the deep ocean circulation and the oceanic cycling of trace metals. The hydrothermal fluid contains dissolved mantle helium that is enriched in 3He relative to the atmosphere, providing an isotopic tracer of the ocean's deep circulation and a marker of hydrothermal sources. This work investigates the potential for the 3He/4He isotope ratio to constrain the ocean's mantle 3He source and to provide constraints on the ocean's deep circulation. We use an ensemble of 11 data-assimilated steady-state ocean circulation models and a mantle helium source based on geographically varying sea-floor spreading rates. The global source distribution is partitioned into 6 regions, and the vertical profile and source amplitude of each region are varied independently to determine the optimal 3He source distribution that minimizes the mismatch between modeled and observed δ3He. In this way, we are able to fit the observed δ3He distribution to within a relative error of ∼15%, with a global 3He source that ranges from 640 to 850 mol yr-1, depending on circulation. The fit captures the vertical and interbasin gradients of the δ3He distribution very well and reproduces its jet-sheared saddle point in the deep equatorial Pacific. This demonstrates that the data-assimilated models have much greater fidelity to the deep ocean circulation than other coarse-resolution ocean models. Nonetheless, the modelled δ3He distributions still display some systematic biases, especially in the deep North Pacific where δ3He is overpredicted by our models, and in the southeastern tropical Pacific, where observed westward-spreading δ3He plumes are not well captured. Sources inferred by the data-assimilated transport with and without isopycnally aligned eddy diffusivity differ widely in the Southern Ocean, in spite of the ability to match the observed distributions of