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Sample records for 4he linejno polyarizovannymi

  1. Dipole Resonances in 4He

    SciTech Connect

    Matsumoto, E.; Nakayama, S.; Hayami, R.; Fushimi, K.; Kawasuso, H.; Yasuda, K.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Fujiwara, M.; Yosoi, M.; Nakanishi, K.; Kawase, K.; Hashimoto, H.; Oota, T.; Sagara, K.; Kudoh, T.; Asaji, S.; Ishida, T.; Tanaka, M.

    2007-02-26

    We investigated the analogs of the giant dipole resonance (GDR) and spin-dipole resonance (SDR) of 4He by using the 4He(7Li,7Be) reaction at an incident energy of 455 MeV and at forward scattering angles. The {delta}S=0 and {delta}S=1 spectra for 4He were obtained by measuring the 0.43-MeV 7Be {gamma}-ray in coincidence with the scattered 7Be. From the {delta}S=0 and {delta}S=1 spectra thus obtained, the strength distributions of the GDR and SDR in 4He can be derived and the results are compared with the previous data.

  2. Condensate fraction in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Olinto, A. C.

    1987-04-01

    Recently, a relationship between the chemical potential and the condensate fracton n0(T) has been derived for all temperatures in the superfluid region. An analysis of liquid 4He chemical-potential data yields n0(T=0)=0.062, and n0(T) is in excellent agreement with the empirical results of Svensson, Sears, and Griffin.

  3. sup 4 He- sup 4 He elastic scattering and variational wave functions

    SciTech Connect

    Usmani, A.A.; Ahmad, I. ); Usmani, Q.N. )

    1992-01-01

    We calculate differential cross sections for {sup 4}He-{sup 4}He elastic scattering at 4.32 GeV/{ital c} in the framework of Glauber multiple scattering theory using correlated variational wave functions as given by the two-nucleon Urbana {ital v}{sub 14} potential and the spin-isospin averaged Melfleit-Tjon force {ital V}. These wave functions are found to give fairly satisfactory results.

  4. Tortuosity of 4He Films on Aerogel

    SciTech Connect

    Ashton, C. E.; Golov, A. I.; Mulders, N.

    2006-09-07

    A torsional oscillator has been used to study the flow of liquid 4He through silica aerogel. The tortuosity and dissipation of the flow in the fractal aerogel environment has been measured, for both capillary condensed films and a fully saturated cell. The scaling of tortuosity as a function of filling fraction has been investigated. We compare the results of our 88%-porous aerogel to a 92%-porous sample where a transverse sound technique was used. Our more sensitive technique has reduced the scatter in both the frequency and dissipation data. Like in the previous transverse sound experiment, we find tortuosity as a function of filling fraction to scale with an exponent of {approx} -1.1. Further experiments are planned, to find the dependence of the exponent on the fractal dimension and porosity of aerogel.

  5. Superfluid 4He dynamics beyond quasiparticle excitations

    NASA Astrophysics Data System (ADS)

    Beauvois, K.; Campbell, C. E.; Dawidowski, J.; Fâk, B.; Godfrin, H.; Krotscheck, E.; Lauter, H.-J.; Lichtenegger, T.; Ollivier, J.; Sultan, A.

    2016-07-01

    The dynamics of superfluid 4He at and above the Landau quasiparticle regime is investigated by high-precision inelastic neutron scattering measurements of the dynamic structure factor. A highly structured response is observed above the familiar phonon-maxon-roton spectrum, characterized by sharp thresholds for phonon-phonon, maxon-roton, and roton-roton coupling processes. The experimental dynamic structure factor is compared to the calculation of the same physical quantity by a dynamic many-body theory including three-phonon processes self-consistently. The theory is found to provide a quantitative description of the dynamics of the correlated bosons for energies up to about three times that of the Landau quasiparticles.

  6. Deeply Virtual Compton Scattering off 4He

    NASA Astrophysics Data System (ADS)

    Joosten, Sylvester; CLAS Collaboration

    2015-10-01

    The European Muon Collaboration (EMC) observed the first signs of a modification of the partonic structure of the nucleon when present in a nuclear medium. The precise nature of these effects, as well as their underlying cause, is yet to be determined. The generalized parton distribution (GPD) framework provides a powerful tool to study the partonic structure of nucleons inside a nucleus. Hard exclusive leptoproduction of a real photon off a nucleon, deeply virtual Compton scattering (DVCS), is presently considered the cleanest experimental access to the GPDs, through the Compton form factors (CFFs). This is especially the case for scattering off the spin-zero helium nucleus, where only a single CFF contributes to the process. The real and imaginary parts of this CFF can be constrained through the beam-spin asymmetry (BSA). We will present the first measurements of the DVCS process off 4He using the CEBAF 6 GeV polarized electron beam and the CLAS detector at JLab. The CLAS detector was supplemented with an inner electromagnetic calorimeter for photons produced at small angles, as well as a radial time projection chamber (RTPC) to detect low-energy recoil nuclei. This setup allowed for a clean measurement of the BSA in both the coherent and incoherent channels.

  7. Crystallization of 4He in aerogel via mass flow from surrounding solid 4He

    NASA Astrophysics Data System (ADS)

    Matsuda, H.; Ochi, A.; Isozaki, R.; Minami, S.; Nomura, R.; Pollanen, J.; Halperin, W. P.; Okuda, Y.

    2016-07-01

    The phase boundary between the quantum solid and the liquid phases of 4He is strongly modified in a porous material. However the phase diagram at very low temperatures remains unexplored. We have used a variable-volume experimental cell with optical access to visualize the crystallization of 4He in silica aerogels with independent control of the pressure and temperature. The onset of crystallization was investigated in two aerogel samples with differing porosity both by pressurization at constant temperature and by cooling at constant pressure. With isothermal pressurization we have established a low-temperature phase diagram for each aerogel, and we find that the equilibrium crystallization pressure is reduced with increasing aerogel porosity. Crystals also began to grow in the aerogel on cooling at fixed pressure below an onset temperature Tgrow. We found that below this temperature the crystallization rate increased with decreasing temperature. The aerogel in our cell was surrounded by bulk crystals of 4He , and surprisingly Tgrow was found to be widely distributed when the surrounding bulk crystals were repressurized. In this experimental arrangement, crystallization within the aerogel on cooling requires mass flow from these exterior bulk crystals and is strongly influenced by the disordered structure at the interface between the bulk solid and the helium within the aerogel.

  8. 4He abundances: Optical versus radio recombination line measurements

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    Accurate measurements of the 4He/H abundance ratio are important in constraining Big Bang nucleosynthesis, models of stellar and Galactic evolution, and H ii region physics. We discuss observations of radio recombination lines using the Green Bank Telescope toward a small sample of H ii regions and planetary nebulae. We report 4He/H abundance ratio differences as high as 15-20% between optical and ratio data that are difficult to reconcile. Using the H ii regions S206 and M17 we determine 4He production in the Galaxy to be dY/dZ = 1.71 ± 0.86.

  9. Sound velocity of liquid 4He in aerogel

    NASA Astrophysics Data System (ADS)

    Matsumoto, Koichi; Arai, Osamu; Okuda, Yuichi; Tajiri, Koji

    2000-07-01

    The sound velocity and attenuation of liquid 4He in 93.7% and 94.6% porosity aerogels were measured for a frequency of 10 MHz. The sound velocity in 93.7% aerogel was larger than that in bulk 4He, whereas that in 94.6% was smaller. A model of the aerogel- 4He composite gave satisfactory agreement with the dependence of the sound velocity on the temperature and the aerogel density. This shows that the normal fluid is clamped to aerogel strands, although the viscous penetration depth is comparable to the typical size of a void in the aerogel.

  10. Quantum Phase Transition of 4He Confined in Nanoporous Media

    SciTech Connect

    Shirahama, Keiya

    2006-09-07

    4He confined in nanoporous media is an excellent model system for studying a strongly correlated Bose liquid and solid in a confinement potential. We studied superfluidity and liquid-solid phase transition of 4He confined in a porous Gelsil glass that had nanopores 2.5 nm in diameter. The obtained pressure-temperature phase diagram is fairly unprecedented: the superfluid transition temperature approaches zero at 3.4 MPa, and the freezing pressure is enhanced by approximately 1 MPa from the bulk one. These features indicate that the confined 4He undergoes a superfluid-nonsuperfluid-solid quantum phase transition at zero temperature. The nonsuperfluid phase may be a localized Bose-condensed state in which global phase coherence is destroyed by a strong correlation between the 4He atoms or by a random potential.

  11. Significant structure theory applied to liquid 4He

    PubMed Central

    Ryoo, Ryong; Jhon, Mu Shik; Eyring, Henry

    1980-01-01

    The large kinetic zero-point motion of 4He molecules has been properly taken into account in the significant structure theory of liquids in order to describe the liquidity of liquid 4He. The Debye and the Bose-Einstein partition functions are used for the solid-like molecules of the normal fluid component and for the whole gas-like molecules, respectively. The solid-like molecules of the superfluid component are considered as ground state molecules without having positional degeneracies. The Bragg-Williams approximation of an order/disorder phase transition has been applied to the λ transition of liquid 4He. Thermodynamic and surface properties of liquid 4He have been calculated up to the critical point. The results are satisfactory when compared with the observed values. PMID:16592747

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  13. Superfluidity of Dense {sup 4}He in Vycor

    SciTech Connect

    Khairallah, Saad A.; Ceperley, D.M.

    2005-10-28

    We calculate properties of a model of {sup 4}He in Vycor using the path integral Monte Carlo method. We find that {sup 4}He forms a distinct layered structure with a highly localized first layer, a disordered second layer with some atoms delocalized and able to give rise to the observed superfluid response, and higher layers of nearly perfect crystals. The addition of a single {sup 3}He atom was enough to bring down the total superfluidity by blocking the exchange in the second layer. Our results are consistent with the persistent liquid-layer model to explain the observations. Such a model may be relevant to the experiments on bulk solid {sup 4}He, if there is a fine network of grain boundaries in those systems.

  14. Heat Capacity of Dilute 3He-4He Monolayer Films

    NASA Astrophysics Data System (ADS)

    Morishita, Masashi

    2016-05-01

    The heat capacities of a small amount of 3He dissolved in monolayer 4He films are measured to clarify natures of monolayer 4He films. With increasing areal density, the measured heat capacities gradually increase and subsequently gradually decrease. With further increase in areal density, the measured heat capacity rapidly decreases to zero over a very narrow areal density range near that of the sqrt{3} × sqrt{3} phase. These slightly complex areal-density variations and dependence on 3He concentration are discussed from the viewpoint of the known properties of 4He films. The behaviors can be explained. However, the expected two-dimensional gas-liquid or gas-solid coexistence is not observed in this study.

  15. Evidence for a superglass state in solid 4He.

    PubMed

    Hunt, B; Pratt, E; Gadagkar, V; Yamashita, M; Balatsky, A V; Davis, J C

    2009-05-01

    Although solid helium-4 (4He) may be a supersolid, it also exhibits many phenomena unexpected in that context. We studied relaxation dynamics in the resonance frequency f(T) and dissipation D(T) of a torsional oscillator containing solid 4He. With the appearance of the "supersolid" state, the relaxation times within f(T) and D(T) began to increase rapidly together. More importantly, the relaxation processes in both D(T) and a component of f(T) exhibited a complex synchronized ultraslow evolution toward equilibrium. Analysis using a generalized rotational susceptibility revealed that, while exhibiting these apparently glassy dynamics, the phenomena were quantitatively inconsistent with a simple excitation freeze-out transition because the variation in f was far too large. One possibility is that amorphous solid 4He represents a new form of supersolid in which dynamical excitations within the solid control the superfluid phase stiffness.

  16. Dendritic crystal growth in pure /sup 4/He

    SciTech Connect

    Franck, J.P.; Jung, J.

    1986-08-01

    Dendritic crystal growth of pure hcp and fcc /sup 4/He was observed at pressures between 210 and 6500 bar. Dendrite morphology depends on fluid supercooling and crystal phase. At large supercooling, dendrites with side arms are observed, whereas at low supercooling dendrites grow without side arms. The morpholpogy of hcp /sup 4/He dendrites is strongly influenced by crystalline anisotropy. Comparison with present theories of dendrite growth show good agreement with the power law dependencies of velocity, tip radius, and Peclet number on supercooling. Numerically, theory predicts much larger velocities than are observed. The stability parameter sigma is found to be much smaller than theoretically predicted.

  17. Response of a Mechanical Oscillator in Solid 4He

    NASA Astrophysics Data System (ADS)

    Ahlstrom, S. L.; Bradley, D. I.; Človečko, M.; Fisher, S. N.; Guénault, A. M.; Guise, E. A.; Haley, R. P.; Kolosov, O.; Kumar, M.; McClintock, P. V. E.; Pickett, G. R.; Polturak, E.; Poole, M.; Todoshchenko, I.; Tsepelin, V.; Woods, A. J.

    2014-04-01

    We present the first measurements of the response of a mechanical oscillator in solid 4He. We use a lithium niobate tuning fork operating in its fundamental resonance mode at a frequency of around 30 kHz. Measurements in solid 4He were performed close to the melting pressure. The tuning fork resonance shows substantial frequency shifts on cooling from around 1.5 K to below 10 mK. The response shows an abrupt change at the bcc-hcp transition. At low temperatures, below around 100 mK, the resonance splits into several overlapping resonances.

  18. Photodisintegration of $^4$He into p+t

    SciTech Connect

    R. Nasseripour, B.L. Berman, N. Benmouna, Y. Ilieva, J.-M. Laget

    2009-10-01

    The two-body photodisintegration of $^4$He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at Jefferson Laboratory. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid $^4$He target. This is the first measurement of the photodisintegration of $^4$He above 0.4 GeV. The differential cross sections for the $\\gamma$$^4$He$\\to pt$ reaction have been measured as a function of photon-beam energy and proton-scattering angle, and are compared with the latest model calculations by J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of $^3$He that demonstrated the great importance of three-body mechanisms in the energy region 0.5-0.8 GeV .

  19. Nuclear polarization corrections to the μ4He+ Lamb shift.

    PubMed

    Ji, C; Nevo Dinur, N; Bacca, S; Barnea, N

    2013-10-01

    Stimulated by the proton radius conundrum, measurements of the Lamb shift in various light muonic atoms are planned at PSI. The aim is to extract the rms charge radius with high precision, limited by the uncertainty in the nuclear polarization corrections. We present an ab initio calculation of the nuclear polarization for μ(4)He(+) leading to an energy correction in the 2S-2P transitions of δ(pol)(A)=-2.47 meV ±6%. We use two different state-of-the-art nuclear Hamiltonians and utilize the Lorentz integral transform with hyperspherical harmonics expansion as few-body methods. We take into account the leading multipole contributions, plus Coulomb, relativistic, and finite-nucleon-size corrections. Our main source of uncertainty is the nuclear Hamiltonian, which currently limits the attainable accuracy. Our predictions considerably reduce the uncertainty with respect to previous estimates and should be instrumental to the μ(4)He(+) experiment planned for 2013.

  20. Sodium dimers on the surface of liquid {sup 4}He

    SciTech Connect

    Ancilotto, F.; DeToffol, G.; Toigo, F.

    1995-12-01

    We have studied the structure of a sodium dimer interacting with liquid {sup 4}He. We calculated the equilibrium configuration and binding energy of a Na{sub 2} molecule solvated in a bulk liquid {sup 4}He ``bubble`` and near the liquid-vapor interface ``dimple`` by using a density-functional approach. We find that the solvated molecule is a metastable state, while the the lowest energy bound state occurs when the molecule lies flat on the surface of the liquid. The binding energy for the ``erect`` dimer is only {similar_to}1 K higher than the flat dimer, with no potential energy barrier between the two orientations, implying relatively free rotations of the molecule on the surface. The small effects of the liquid environment on the vibrational properties of the dimer are investigated.

  1. Overview on Solid 4He and the Issue of Supersolidity

    NASA Astrophysics Data System (ADS)

    Chan, M. H. W.; Hallock, R. B.; Reatto, L.

    2013-09-01

    Here we provide an overview of the status of the field of solid 4He with a focus on the recent theoretical and experimental activities stimulated by the 2004 experiments of Kim and Chan. The overview attempts to place the experimental and theoretical work in context, to respect the historical flow of the field and discuss our present understanding of the question of supersolidity in 4He. The possibility of supersolidity in cold atoms and in other systems is also addressed. Special issues of the Journal of Low Temperature Physics (168(3/4), 2012; 169(3/4), 2012), in addition to this issue, have been devoted to this subject and this overview is meant to accompany those issues of the journal.

  2. Bose-Einstein condensation in liquid 4He under pressure

    SciTech Connect

    Glyde, Henry R; Omar Diallo, Souleymane; Azuah, Richard T; Kirichek, Oleg; Taylor, Jon W.

    2011-01-01

    We present neutron scattering measurements of Bose-Einstein condensation, the atomic momen- tum distribution and Final State effects in liquid 4He under pressure. The condensate fraction at low temperature is found to decrease from n0 = 7.25 0.75% at SVP (p 0) to n0 = 3.2 0.75% at pressure p = 24 bar. This indicates an n0 = 3.0% in the liquid at the liquid/solid co-existence line (p = 25.3 bar). The atomic momentum distribution n(k) has high occupation of low k states and differs significantly from a Gaussian (e.g. a classical n(k)). Both n(k) and the Final state function broaden with increasing pressure, reflecting the increased localization of the 4He in space under increased pressure.

  3. 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.

  4. Hyperspherical coupled channel calculations of energy and structure of 4He-4He-Li+ and its isotopic combinations

    NASA Astrophysics Data System (ADS)

    Liu, Min-min; Wu, Meng-Shan; Han, Hui-li; Shi, Ting-yun

    2016-07-01

    The ground state vibrational energy and spatial features of 4He-4He-Li+ and its triatomic isotopic complexes are studied using the slow variable discretization (SVD) method in the hyperspherical coordinates for the zero total angular momentum. Our results show that the dominant structure of the system is an isosceles triangle with the shorter side associated with the two Li+-He distances using the sum-of-potential approximation. Corrections caused by the induced dipole-induced dipole interactions on the He atoms are also investigated. The effects are seen to be small and have a minor influence on the binding energy and the structure of present system. The results are also compared with the full ab initio calculations including all the three-body interactions and information of three-body corrections is obtained.

  5. Hyperspherical coupled channel calculations of energy and structure of (4)He-(4)He-Li(+) and its isotopic combinations.

    PubMed

    Liu, Min-Min; Wu, Meng-Shan; Han, Hui-Li; Shi, Ting-Yun

    2016-07-21

    The ground state vibrational energy and spatial features of (4)He-(4)He-Li(+) and its triatomic isotopic complexes are studied using the slow variable discretization (SVD) method in the hyperspherical coordinates for the zero total angular momentum. Our results show that the dominant structure of the system is an isosceles triangle with the shorter side associated with the two Li(+)-He distances using the sum-of-potential approximation. Corrections caused by the induced dipole-induced dipole interactions on the He atoms are also investigated. The effects are seen to be small and have a minor influence on the binding energy and the structure of present system. The results are also compared with the full ab initio calculations including all the three-body interactions and information of three-body corrections is obtained. PMID:27448884

  6. Solidification of 4He clusters adsorbed on graphene

    NASA Astrophysics Data System (ADS)

    Markić, L. Vranješ; Stipanović, P.; Bešlić, I.; Zillich, R. E.

    2016-07-01

    We determined the ground state of He4N clusters adsorbed on one side of graphene for selected cluster sizes in the range from N =20 to N =127 . For all investigated clusters variational and diffusion Monte Carlo simulations were performed at T =0 K, and in addition for a selected subset finite temperature path integral Monte Carlo. At T =0 K the liquid or solid character of each cluster was investigated by restricting the phase using corresponding importance sampling trial-wave functions. The 4He-graphene interaction was modeled as a sum of individual 4He-C interactions, where both isotropic and anisotropic models were tested; also the effect of the substrate-mediated McLachlan interaction was investigated. We have found homogeneous crystallization in models of anisotropic interactions, starting from clusters with N =26 atoms in simulations without the McLachlan interaction, and between N =37 and 61 when it is included. The atoms become increasingly delocalized as one moves from the center of the cluster to the perimeter, evidenced by the Lindemann parameter. On the other hand, in the case of the isotropic interaction model, a liquidlike structure is more favorable for all considered cluster sizes. We use a liquid-drop model to extrapolate the energy per particle to the N →∞ limit, and the results are compared with the values obtained in studies of bulk 4He on graphene. Low-temperature path integral Monte Carlo simulations are in agreement with ground-state results.

  7. Density pattern in supercritical flow of liquid {sup 4}He

    SciTech Connect

    Ancilotto, F.; Toigo, F.; Dalfovo, F.; Pitaevskii, L.P.

    2005-03-01

    A density-functional theory is used to investigate the instability arising in superfluid {sup 4}He as it flows at velocity u just above the Landau critical velocity of rotons v{sub c}. Confirming an early theoretical prediction by one of us [JETP Lett. 39, 511 (1984)], we find that a stationary periodic modulation of the density occurs, with amplitude proportional to (u-v{sub c}){sup 1/2} and wave vector equal to the roton wave vector. This density pattern is studied for supercritical flow both in bulk helium and in a channel of nanometer cross section.

  8. Quantum Monte Carlo Simulation of Overpressurized Liquid {sup 4}He

    SciTech Connect

    Vranjes, L.; Boronat, J.; Casulleras, J.; Cazorla, C.

    2005-09-30

    A diffusion Monte Carlo simulation of superfluid {sup 4}He at zero temperature and pressures up to 275 bar is presented. Increasing the pressure beyond freezing ({approx}25 bar), the liquid enters the overpressurized phase in a metastable state. In this regime, we report results of the equation of state and the pressure dependence of the static structure factor, the condensate fraction, and the excited-state energy corresponding to the roton. Along this large pressure range, both the condensate fraction and the roton energy decrease but do not become zero. The roton energies obtained are compared with recent experimental data in the overpressurized regime.

  9. Classical Rotational Inertia of Solid {sup 4}He

    SciTech Connect

    Dash, J.G.; Wettlaufer, J.S.

    2005-06-17

    The observation of reduced rotational inertia in a cell containing solid {sup 4}He has been interpreted as evidence for superfluidity of the solid. We propose an alternative explanation: slippage of the solid, due to grain boundary premelting between the solid and dense adsorbed layers at the container wall. We calculate the range of film thickness, and determine the viscosity that will account for the missing rotational inertia. Grain boundary premelting also explains inertial anomalies in an earlier study of solid helium in porous glass and indicates that the liquid is partially superfluid.

  10. Electron-Induced Neutron Knockout from 4He

    NASA Astrophysics Data System (ADS)

    Misiejuk, A.; Papandreou, Z.; Voutier, E.; Bauer, Th. S.; Blok, H. P.; Boersma, D. J.; den Bok, H. W.; Bruins, E. E.; Farzanpay, F.; Grüner, K.; Hesselink, W. H.; Huber, G. M.; Jans, E.; Kalantar-Nayestanaki, N.; Kasdorp, W.-J.; Konijn, J.; Laget, J.-M.; Lapikás, L.; Lolos, G. J.; Onderwater, G. J.; Pellegrino, A.; Schroevers, R.; Spaltro, C. M.; Starink, R.; van der Steenhoven, G.; Steiger, J. J.; Visschers, J. L.; Willering, H. W.; Yeomans, D. M.

    2002-10-01

    The differential cross section for electron-induced neutron knockout in the reaction 4He(e,e'n)3He has been measured for the first time with a statistical accuracy of 11%. The experiment was performed in quasielastic kinematics at a momentum transfer of 300 MeV/c and in the missing-momentum range of 25-70 MeV/c. The comparison of the data with theoretical calculations shows an impressive increase of the cross section resulting from final state interaction effects. Specifically , the p-n charge-exchange process dominates the cross section in this kinematical regime.

  11. Compression-Driven Mass Flow in Bulk Solid 4He

    NASA Astrophysics Data System (ADS)

    Cheng, Zhi Gang; Beamish, John

    2016-07-01

    Mass flow has been observed in solid 4He coexisting with superfluid confined in Vycor, but its physical mechanism remains an open question. Here we report observations of flow in experiments in which Vycor has been eliminated, allowing us to study the intrinsic flow in solid 4He without the complications introduced by the presence of superfluid and the associated solid-liquid interfaces. By growing crystals with 3He concentration as low as x3=5 ×10-12, we also avoided the low temperature flow suppression observed in previous experiments and found that the flow rate continued to increase down to at least 28 mK without saturation. In addition, 3He concentrations of 120 ppb, which suppressed most of the low temperature flow in previous experiments, had no effect in our samples. The larger 3He concentrations needed to block the bulk solid flow suggest that the mass flow involves a larger area, such as disordered liquid layer on solid surface and grain boundaries.

  12. Sliding Wigner solid on liquid {sup 4}He

    SciTech Connect

    Shirahama, Keiya; Kono, Kimitoshi

    1996-08-01

    The authors report a systematic experimental study of the anomalous nonlinear magnetotransport in the Wigner solid (WS) trapped on a liquid {sup 4}He surface. The ac Corbino conductivity {sigma}{sub xx} exhibits an abrupt jump at a certain driving voltage. The threshold input voltage V{sub th} for the {sigma}{sub xx} jump varies as V{sub th} {proportional_to}B{sup {minus}0.8}{omega}{sup {minus}1}n{sub s}{sup 1.5}E{sub {perpendicular}}, where B, {omega}, n{sub s}, and E{sub {perpendicular}} are magnetic field, frequency, electron density and pressing electric field, respectively. The authors interpret the {sigma}{sub xx} jump as the transition between the WS accompanied with the periodic {sup 4}He surface deformation and the WS which decouples from the surface, due to the large driving force. A simple model is presented: The rigid-potential sliding model qualitatively explains the above mentioned behaviors of V{sub th}. They have found that the dependences of {sigma}{sub xx} on B and E{sub {perpendicular}} are different from those of the liquid phase. The anomalous behaviors of {sigma}{sub xx} play a crucial role on the sliding model.

  13. Compression-Driven Mass Flow in Bulk Solid ^{4}He.

    PubMed

    Cheng, Zhi Gang; Beamish, John

    2016-07-01

    Mass flow has been observed in solid ^{4}He coexisting with superfluid confined in Vycor, but its physical mechanism remains an open question. Here we report observations of flow in experiments in which Vycor has been eliminated, allowing us to study the intrinsic flow in solid ^{4}He without the complications introduced by the presence of superfluid and the associated solid-liquid interfaces. By growing crystals with ^{3}He concentration as low as x_{3}=5×10^{-12}, we also avoided the low temperature flow suppression observed in previous experiments and found that the flow rate continued to increase down to at least 28 mK without saturation. In addition, ^{3}He concentrations of 120 ppb, which suppressed most of the low temperature flow in previous experiments, had no effect in our samples. The larger ^{3}He concentrations needed to block the bulk solid flow suggest that the mass flow involves a larger area, such as disordered liquid layer on solid surface and grain boundaries. PMID:27447513

  14. Quantized Vortex State in hcp Solid 4He

    NASA Astrophysics Data System (ADS)

    Kubota, Minoru

    2012-11-01

    The quantized vortex state appearing in the recently discovered new states in hcp 4He since their discovery (Kim and Chan, Nature, 427:225-227, 2004; Science, 305:1941, 2004) is discussed. Special attention is given to evidence for the vortex state as the vortex fluid (VF) state (Anderson, Nat. Phys., 3:160-162, 2007; Phys. Rev. Lett., 100:215301, 2008; Penzev et al., Phys. Rev. Lett., 101:065301, 2008; Nemirovskii et al., arXiv:0907.0330, 2009) and its transition into the supersolid (SS) state (Shimizu et al., arXiv:0903.1326, 2009; Kubota et al., J. Low Temp. Phys., 158:572-577, 2010; J. Low Temp. Phys., 162:483-491, 2011). Its features are described. The historical explanations (Reatto and Chester, Phys. Rev., 155(1):88-100, 1967; Chester, Phys. Rev. A, 2(1):256-258, 1970; Andreev and Lifshitz, JETP Lett., 29:1107-1113, 1969; Leggett, Phys. Rev. Lett., 25(22), 1543-1546, 1970; Matsuda and Tsuneto, Prog. Theor. Phys., 46:411-436, 1970) for the SS state in quantum solids such as solid 4He were based on the idea of Bose Einstein Condensation (BEC) of the imperfections such as vacancies, interstitials and other possible excitations in the quantum solids which are expected because of the large zero-point motions. The SS state was proposed as a new state of matter in which real space ordering of the lattice structure of the solid coexists with the momentum space ordering of superfluidity. A new type of superconductors, since the discovery of the cuprate high T c superconductors, HTSCs (Bednorz and Mueller, Z. Phys., 64:189, 1986), has been shown to share a feature with the vortex state, involving the VF and vortex solid states. The high T c s of these materials are being discussed in connection to the large fluctuations associated with some other phase transitions like the antiferromagnetic transition in addition to that of the low dimensionality. The supersolidity in the hcp solid 4He, in contrast to the new superconductors which have multiple degrees of freedom of

  15. Dissipation of Quasiclassical Turbulence in Superfluid ^{4}He.

    PubMed

    Zmeev, D E; Walmsley, P M; Golov, A I; McClintock, P V E; Fisher, S N; Vinen, W F

    2015-10-01

    We compare the decay of turbulence in superfluid ^{4}He produced by a moving grid to the decay of turbulence created by either impulsive spin-down to rest or by intense ion injection. In all cases, the vortex line density L decays at late time t as L∝t^{-3/2}. At temperatures above 0.8 K, all methods result in the same rate of decay. Below 0.8 K, the spin-down turbulence maintains initial rotation and decays slower than grid turbulence and ion-jet turbulence. This may be due to a decoupling of the large-scale superfluid flow from the normal component at low temperatures, which changes its effective boundary condition from no-slip to slip.

  16. Dislocation Structure and Mobility in hcp ^{4}He.

    PubMed

    Landinez Borda, Edgar Josué; Cai, Wei; de Koning, Maurice

    2016-07-22

    Using path-integral Monte Carlo simulations, we assess the core structure and mobility of the screw and edge basal-plane dislocations in hcp ^{4}He. Our findings provide key insights into recent interpretations of giant plasticity and mass flow junction experiments. First, both dislocations are dissociated into nonsuperfluid Shockley partial dislocations separated by ribbons of stacking fault, suggesting that they are unlikely to act as one-dimensional channels that may display Lüttinger-liquid-like behavior. Second, the centroid positions of the partial cores are found to fluctuate substantially, even in the absence of applied shear stresses. This implies that the lattice resistance to motion of the partial dislocations is negligible, consistent with the recent experimental observations of giant plasticity. Further results indicate that both the structure of the partial cores and the zero-point fluctuations play a role in this extreme mobility. PMID:27494477

  17. X-rays from antiprotonic3He and4He

    NASA Astrophysics Data System (ADS)

    Schneider, M.; Bacher, R.; Blüm, P.; Gotta, D.; Heitlinger, K.; Kunold, W.; Rohmann, D.; Egger, J.; Simons, L. M.; Elsener, K.

    1991-06-01

    Antiprotonic X-rays from the helium isotopes have been observed at pressures of 36, 72, 375 and 600 mbar. The antiproton beam from LEAR with momenta of 309 and 202 MeV/c has been stopped at these pressures using the cyclotron trap. The X-rays were detected with Si (Li) and intrinsic Ge semiconductor detectors. Absolute X-ray yields were determined and the strong-interaction 2p shifts and the 2p and 3d broadenings measured to be ɛ2p=(-17±4) eV, Γ2p=(25±9) eV and Γ3d=(2.14 ±0.18) meV for ¯p3He and ɛ2p=(-18±2) eV, Γ2p =(45±5) eV and Γ3d=(2.36±0.10) meV for ¯p4He.

  18. Dislocation Structure and Mobility in hcp 4He

    NASA Astrophysics Data System (ADS)

    Landinez Borda, Edgar Josué; Cai, Wei; de Koning, Maurice

    2016-07-01

    Using path-integral Monte Carlo simulations, we assess the core structure and mobility of the screw and edge basal-plane dislocations in hcp 4He. Our findings provide key insights into recent interpretations of giant plasticity and mass flow junction experiments. First, both dislocations are dissociated into nonsuperfluid Shockley partial dislocations separated by ribbons of stacking fault, suggesting that they are unlikely to act as one-dimensional channels that may display Lüttinger-liquid-like behavior. Second, the centroid positions of the partial cores are found to fluctuate substantially, even in the absence of applied shear stresses. This implies that the lattice resistance to motion of the partial dislocations is negligible, consistent with the recent experimental observations of giant plasticity. Further results indicate that both the structure of the partial cores and the zero-point fluctuations play a role in this extreme mobility.

  19. Theoretical modeling of electron mobility in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Aitken, Frédéric; Bonifaci, Nelly; von Haeften, Klaus; Eloranta, Jussi

    2016-07-01

    The Orsay-Trento bosonic density functional theory model is extended to include dissipation due to the viscous response of superfluid 4He present at finite temperatures. The viscous functional is derived from the Navier-Stokes equation by using the Madelung transformation and includes the contribution of interfacial viscous response present at the gas-liquid boundaries. This contribution was obtained by calibrating the model against the experimentally determined electron mobilities from 1.2 K to 2.1 K along the saturated vapor pressure line, where the viscous response is dominated by thermal rotons. The temperature dependence of ion mobility was calculated for several different solvation cavity sizes and the data are rationalized in the context of roton scattering and Stokes limited mobility models. Results are compared to the experimentally observed "exotic ion" data, which provides estimates for the corresponding bubble sizes in the liquid. Possible sources of such ions are briefly discussed.

  20. Dynamics of Laser Ablation in Superfluid ^4He

    NASA Astrophysics Data System (ADS)

    Buelna, X.; Popov, E.; Eloranta, J.

    2016-10-01

    Pulsed laser ablation of metal targets immersed in superfluid ^4He is visualized by time-resolved shadowgraph photography and the products are analyzed by post-experiment atomic force microscopy (AFM) measurements. The expansion dynamics of the gaseous ablation half-bubble on the target surface appears underdamped and follows the predicted behavior for the thermally induced bubble growth mechanism. An inherent instability of the ablation bubble appears near its maximum radius and no tightly focused cavity collapse or rebound events are observed. During the ablation bubble retreat phase, the presence of sharp edges in the target introduces flow patterns that lead to the creation of large classical vortex rings. Furthermore, on the nanometer scale, AFM data reveal that the metal nanoparticles created by laser ablation are trapped in spherical vortex tangles and quantized vortex rings present in the non-equilibrium liquid.

  1. cap alpha. /sup 4/He elastic scattering at high energies

    SciTech Connect

    Usmani, A.A.; Ahmad, I.; Usmani, Q.N.

    1989-03-01

    Differential cross sections for ..cap alpha.. /sup 4/He elastic scattering have been calculated at incident ..cap alpha..-particle momenta of 4.32, 5.07, and 7.0 GeV/c within the framework of Glauber multiple scattering theory. The full Glauber amplitude has been calculated using the Monte Carlo method for evaluating multidimensional integrals. We found that, in general, the more realistic double-Gaussian model for the density brings theory closer to experiment as compared to the generally used single-Gaussian model in some momentum transfer regions. Our results with the double-Gaussian model and an acceptable set of NN parameters are in fairly good agreement with the experimental data at 4.32 and 5.07 GeV/c.

  2. Theoretical modeling of electron mobility in superfluid (4)He.

    PubMed

    Aitken, Frédéric; Bonifaci, Nelly; von Haeften, Klaus; Eloranta, Jussi

    2016-07-28

    The Orsay-Trento bosonic density functional theory model is extended to include dissipation due to the viscous response of superfluid (4)He present at finite temperatures. The viscous functional is derived from the Navier-Stokes equation by using the Madelung transformation and includes the contribution of interfacial viscous response present at the gas-liquid boundaries. This contribution was obtained by calibrating the model against the experimentally determined electron mobilities from 1.2 K to 2.1 K along the saturated vapor pressure line, where the viscous response is dominated by thermal rotons. The temperature dependence of ion mobility was calculated for several different solvation cavity sizes and the data are rationalized in the context of roton scattering and Stokes limited mobility models. Results are compared to the experimentally observed "exotic ion" data, which provides estimates for the corresponding bubble sizes in the liquid. Possible sources of such ions are briefly discussed. PMID:27475346

  3. Σ production from targets of ^4He and ^13C

    NASA Astrophysics Data System (ADS)

    Chrien, R. E.

    1996-10-01

    One of the abiding issues in hypernuclear research has been the question of the formation of nuclear bound states incorporating the Σ-hyperon. The recent increases in beam intensity at the Brookhaven AGS have enabled us to obtain a high statistics study on the production of Σ-hyperons on a ^4He target. Earlier research using stopped kaons at KEK indicated the presence of structure in the (K^-,π^-) reaction, and led to the postulate of a Σ bound state. That structure has now been definitely confirmed in the in-flight kaon experiment at the LESB2 beam line and Moby-Dick spectrometer. An improved measurement of the binding energy of the presumed state will be reported, together with a production cross section. In addition, both (K^-,π^-) and (K^-,π^+) reactions on ^13C have been studied and will be compared to similar measurements on ^9Be.

  4. Observation of melting of solid 4He by sound wave

    NASA Astrophysics Data System (ADS)

    Okuda, Y.; Yamazaki, S.; Yoshida, T.; Fujii, H.; Matsumoto, K.

    1999-03-01

    We have observed the crystal melting, or the depletion of the solid/liquid interface where the strong pulsed sound beam was passing. The crystal was produced around 0.8 K with the atomically rough horizontal surface sitting in the middle of the sample cell. The interface was very mobile which was confirmed by an easy excitation of the crystallization/melting wave. When the received signal through the interface was monitored as a function of the input power, a sudden saturation of the received signal was observed at some power. For well above that power, the melting of the interface was visible through a video camera for both the cases of the sound emission from fluid-side and solid-side. This would be the first observation of sound induced melting of solid 4He.

  5. Magnetic-field-assisted atomic polarization spectroscopy of 4 He

    NASA Astrophysics Data System (ADS)

    Li, Sheng; Wang, Haidong; Wu, Teng; Peng, Xiang; Guo, Hong; Cream Team

    2016-05-01

    Atomic polarization spectroscopy (PS) is a high resolution sub-Doppler atomic spectroscopic technique with free modulation. It is always desirable to obtain a PS signal with zero background as it can provide a more preferable laser frequency stabilization performance. There are many factors that can affect the PS signal background, i.e., the laser power, the laser polarization and the magnetic field. Here, we demonstrate a method for observing and analyzing the effects on the PS signal of 4 He under different magnetic fields. At the beginning, under nearly zero magnetic field, the large asymmetrical PS signal background has been observed and cannot be eliminated by only optically adjusting. Then, we find that the PS signal profile can be changed and controlled by varying the magnetic field with transverse or longitudinal direction and different intensity. The optimized PS signal with symmetrical dispersive profile and zero background is obtained when the magnetic field is chosen and controlled in the transverse direction and more than 20000nT intensity. Similar phenomenon cannot be observed under the longitudinal magnetic field. A theoretical model is also presented, which explains and agrees well with our experimental results.

  6. Correlation of Excess Enthalpy and ^4He Production: a Review

    NASA Astrophysics Data System (ADS)

    Miles, M. H.

    2004-03-01

    Three different sets of experiments conducted in the Navy Laboratory (NAWCWD) at China Lake, California (1990-1994) clearly established that helium-4 is the main fusion product in the Pd/D_2O+LiOD electrolysis system(P.A. Mosier-Boss, S.R. Chubb, M. Fleischmann, M. Imam, M. H. Miles, S. Szpak, TR 1862, SPAWAR Systems Center, San Diego; see http://www.lenr-canr.org/acrobat/MosierBossthermaland.pdf). A correlation between excess enthalpy and excess helium-4 was measured in 18 out of 21 experiments. The observation of no excess enthalpy was correlated with no excess helium in 12 out of 12 experiments. Thus 30 out of 33 experiments agree with the hypothesis that the excess enthalpy produced in cold fusion studies is correlated with helium-4 production: d+darrow ^4He + 23.8 MeV. Furthermore, the measured rate of helium-4 production was always in the appropriate range of 10^1^0 to 10^1^2 atoms per second per watt of excess power.

  7. Creep in solid 4He at temperatures below 1 K

    NASA Astrophysics Data System (ADS)

    Zhuchkov, V. A.; Lisunov, A. A.; Maidanov, V. A.; Neoneta, A. S.; Rubanskyi, V. Yu.; Rubets, S. P.; Rudavskii, E. Ya.; Smirnov, S. N.

    2015-03-01

    Creep in solid 4He at temperatures of ˜100-1000 mK is studied experimentally by detecting the flow of helium through a frozen porous membrane under a constant external force. Creep curves are measured for different temperatures and mechanical stresses. This method has made it possible to detect low creep rates in helium down to the lowest temperatures in these experiments. It is found that throughout this temperature range, creep is thermally activated and the activation energy decreases with falling temperature and increasing mechanical stress. An analysis shows that for temperatures above ≈500 mK, Nabarro-Herring diffusive creep takes place in solid helium with mass transfer by self diffusion of atoms and a counterflow of vacancies. The experimental data have been used to obtain the self-diffusion coefficient as a function of temperature for different stresses. At temperatures below ≈500 mK creep takes place at a very low flow rate (˜10-13 cm/s) and a very low activation energy (˜0.5-0.7 K), while the creep mechanism remains unclear.

  8. Stress induced roughening of superclimbing dislocation in solid 4He

    NASA Astrophysics Data System (ADS)

    Aleinikava, Darya; Kuklov, Anatoly

    2011-03-01

    We investigate numerically superclimb of dislocation in solid 4 He biased by externally imposed chemical potential μ . The effective action takes into account quantum phase slips in the core superfluid as well as the core displacement in Peierls potential within the Granato-Lücke string model. The bias produces stress on the core and this can result in dislocation roughening. Such roughening is characterized by hysteretic behavior at temperatures (T) below some threshold Thyst . At T >Thyst strongresonantpeaksdevelopinthedislocationdifferentialresponse . Thesepeaksexhibitperiodicbehaviorvs μ, with the period determined by Peierls potential and dislocation length. We explain these effects by thermally assisted tunneling of jog-antijog pairs across the barrier created by Peierls potential and the bias. Since superclimbing is controlled by core superflow, speed of sound along the superfluid core exhibits dip-like features at the peak positions. We propose that this effect is seen in the mass transport experiment. We acknowledge support by NSF, grants PHY1005527 and PHY0653135,and by CUNY, grant 63071-00 41.

  9. Critical behavior of liquid {sup 4}He at negative pressures

    SciTech Connect

    Campbell, C.E.; Folk, R.; Krotscheck, E.

    1996-10-01

    The authors examine the equation of state of liquid {sup 4}He at negative pressures close to the spinodal density {rho}{sub s} where the hydrodynamic speed of sound vanishes. The non-analytic behavior of the equation of state and the speed of sound in the vicinity of the spinodal density are calculated in two and in three dimensions; they find for the speed of sound the non-analytic behavior mc{sub s}{sup 2} {approximately} ({rho}-{rho}{sub s}){sup 2/5} in three dimensions and mc{sub s}{sup 2} {approximately} [({rho}-{rho}{sub s})/{vert_bar}ln({rho}-{rho}{sub s}){vert_bar}]{sup 1/2} in two dimensions. The authors then examine the low density regime numerically, using a semianalytic microscopic theory. It is found that non-analytic exponents are visible only in a negligible density regime around the spinodal point. Estimates for the spinodal densities, and the range of critical fluctations are provided.

  10. 4He behavior in calcite filling viewed by (U-Th)/He dating, 4He diffusion and crystallographic studies

    NASA Astrophysics Data System (ADS)

    Cros, Alexandre; Gautheron, Cécile; Pagel, Maurice; Berthet, Patrick; Tassan-Got, Laurent; Douville, Eric; Pinna-Jamme, Rosella; Sarda, Philippe

    2014-01-01

    Fault-filling calcite crystals sampled from the Eocene/Oligocene Gondrecourt graben, Paris Basin, Eastern France, have been studied in order to test the potentiality of calcite (U-Th)/He dating, based on recognized He retention behavior in crystal lattice at surface temperature (Copeland et al., 2007). The samples have been selected because of their relatively old Eocene to Oligocene precipitation age and cold thermal history (<40 °C since precipitation). They were sorted into three main tectonic and morphological groups in order of precipitation, including (1) micro-fracture calcites, (2) breccia and associated geodic calcites, and (3) vein and associated geodic calcites. (U-Th)/He dating of 63 calcite fragments yields ages dispersed from 0.2 ± 0.02 to 35.8 ± 2.7 Ma, as well as two older dates of 117 ± 10 and 205 ± 28 Ma (1σ). These He ages correlate with grain chemistry, such as Sr, ΣREE concentrations or (La/Yb)N ratios, likely reflecting parent fluid evolution. Only the oldest He ages, which correspond to the most recently precipitated crystals, have preserved the total 4He budget since precipitation. To better understand both the age dispersion and why calcites precipitated earlier show younger ages, 4He diffusion experiments have been conducted on 10 Gondrecourt calcite fragments from 3 samples with He ages of ∼0.2-6 Ma. Additionally, a crystallographic investigation by X-ray diffraction (XRD) performed on similar samples reveals that crystal structure evolves with increasing temperature, beginning with micro-cracks and cleavage opening. These XRD results shed light on the (U-Th)/He data, indicating that, in fault-filling calcite, He retention is controlled by multiple diffusion domains (MDD) with various sizes, and therefore, evolves through time with strong consequences on (U-Th)/He age. We thus interpret the Gondrecourt calcite (U-Th)/He age scatter as a consequence of the production of defects due to successive calcite crystallization phases

  11. Thermal properties of {sup 4}He surfaces and interfaces

    SciTech Connect

    Clements, B.E.; Krotscheck, E. |; Tymczak, C.J.

    1997-05-01

    A first-principle quantum statistical mechanical theory is used to study the properties of thick liquid {sup 4}He films absorbed to the weakly binding substrates: Li, Na, and Cs. Values for the liquid-gas and solid-liquid surface energies are determined. By fitting, at long wavelengths, the film`s lowest energy mode with the standard expression for the ripplon energy, which depends on the liquid-gas surface energy, the authors obtain excellent agreement with the liquid-vacuum surface energy from recent experiments and also the one previously extracted from quantum liquid droplet calculations. The full spectrum of excitations for wave vectors less than 0.50 {Angstrom}{sup {minus}1} is calculated using a dynamical correlated basis function theory developed in earlier work, which includes multi-phonon scattering processes. Particle currents and transition densities are used to elucidate the nature of the excitations. At a coverage of 0.40 {Angstrom}{sup {minus}2}, the lowest mode shows no significant substrate dependence, and is recognized as being a ripplon propagating in the liquid film at the liquid-gas surface. A new effect is observed for the Cs substrate; the second lowest mode is qualitatively different than found on the other substrates and is identified as interfacial ripplon. In the other substrates the second mode is a volume mode altered somewhat by the high density inner liquid layers. The linewidths of these modes are also calculated. The dynamic excitations provide the input for the thermodynamic theory and the effects on the free energy, heat capacity, and thermal surface broadening of these films are studied as function of the nature of the excitations, the number of modes, and variations in the substrate potentials.

  12. Experiments on Rogue Waves in Superfluid 4He

    NASA Astrophysics Data System (ADS)

    Efimov, Viktor; McClintock, Peter; Ganshin, Andrei; Kolmakov, German; Mezhov-Deglin, Leonid

    2010-05-01

    We describe an experimental and theoretical study of nonlinear wave interactions in superfluid helium and report the observation of rogue waves. Rogue waves (or freak waves, or killer waves, or extreme waves) have long been recognized by sailors as a menace to shipping and are believed to have been responsible for the unexplained losses of vessels of all sizes, including e.g. 22 super-carriers between 1968 and 1994 [1, 2]. Rogue waves on the ocean are rare, and are much higher (and steeper) than all the other waves around them. They seem to appear from nowhere and subsequently to disappear without trace [3]. Following the famous 'New Year wave' measured by instruments on the Draupner North Sea oil rig at the beginning of 1995, the existence of oceanic rogue waves is no longer in doubt. There have been several suggestions about possible mechanisms for the creation of rogue waves. These include the combined effects of wind and currents, and the focusing effects associated with the profile of the ocean floor and nearby shorelines. Where rogue waves appear in deep water far from any shore, which they sometimes do, it seems likely that they must evolve through nonlinear interactions within the 'noisy background" of smaller wind-blown waves [4]. Rogue waves have been modeled theoretically, especially by exploiting the special properties of the nonlinear Schrödinger equation. They have been sought experimentally and/or studied in large wave tanks [5], optical systems [6, 7], and superfluid 4He [8]. Our experimental system consists of high intensity second sound (temperature-entropy) waves within a resonant cavity filled with superfluid 4He at 2.1 K. Under steady state conditions, with a constant oscillatory driving force at the resonant frequency, the second sound waves are turbulent and fluxes of energy flow towards both high and low frequencies. It is found that rogue waves appear under the nonequilibrium conditions that prevail shortly after the drive has been

  13. Four-body calculation of the first excited state of 4He using a realistic NN interaction: 4He (e, e' ) 4He ( 0+2 ) and the monopole sum rule

    NASA Astrophysics Data System (ADS)

    Hiyama, E.; Gibson, B. F.; Kamimura, M.

    2004-09-01

    4He possesses a second 0+ state; the transition form factor has been measured via inelastic electron scattering. The nature of the 0+2 state’s spatial structure has been controversial. An accurate four-nucleon calculation utilizing a realistic NN force (Argonne V 8' ) plus phenomenological NNN three-body force has been performed for both the 4He ground state and second 0+ state ( Ex =20.21 MeV) using the Gaussian expansion method. The calculated one-body densities and transition density show a significant difference between the states. The resulting impulse approximation transition form factor 4He (e, e' ) 4He ( 0+2 ) agrees with the available data. The overlap of the 0+2 wave function with the trinucleon ground state suggests that the structure is primarily a loosely bound 3N+N system and not a breathing mode. It is found that a major part of the energy-weighted E0 sum rule value is exhausted by nonresonant, low-energy continuum states other than the second 0+ state, in contrast to heavier nuclei where a dominant fraction of the sum-rule limit is exhausted by the second 0+ state because it corresponds to a collective, breathing mode.

  14. Quantum effects in the sorption kinetics of 4He by mesoporous materials

    NASA Astrophysics Data System (ADS)

    Dolbin, A. V.; Khlistyuck, M. V.; Esel'son, V. B.; Gavrilko, V. G.; Vinnikov, N. A.; Basnukaeva, R. M.; Danchuk, V. V.

    2016-02-01

    Sorption and desorption of 4He by a mesoporous silicate material MCM-41 was studied in the temperature range of 1.5-290 K. It was shown that for T = 25-290 K the thermal activation mechanism is dominant in the sorption kinetics of 4He atoms by an MCM-41 sample. Its activation energy was estimated as Ea ≈ 164.8 K. For T = 12-23 K, the diffusion of 4He atoms in the MCM-41 was practically independent of temperature, which typically occurs when the tunnelling mechanism of diffusion dominates over the thermally activated one. A change in the mobility of 4He atoms in MCM-41 channels was observed at T = 6-12 K, which may be indicative of the formation upon cooling (or decay upon heating) of a 4He monolayer and subsequent multilayers on the inner surfaces of the channels. Below 6 K, the diffusion coefficients of 4He are only weakly temperature dependent, which may be attributed to the behavior of quantum 4He liquid in the MCM-41 channels covered with several layers of 4He atoms.

  15. Anisotropic superfluidity of {sup 4}He on a C{sub 36} fullerene molecule

    SciTech Connect

    Park, Sungjin; Kim, Byeongjoon; Kwon, Yongkyung

    2015-09-14

    We have performed path-integral Monte Carlo calculations to study the adsorption of {sup 4}He atoms on two different C{sub 36} isomers with the D{sub 6h} and the D{sub 2d} symmetries. The radial {sup 4}He density distributions reveal layer-by-layer growth with the first layer being located at a distance of ∼5.5 Å from the C{sub 36} molecular center and the second layer at ∼8.3 Å. From the angular density profiles of {sup 4}He, we find different quantum states as the number of {sup 4}He adatoms N varies. For N = 20, we observe commensurate solid structures on both D{sub 6h} and D{sub 2d} isomers, where each of 8 hexagon and 12 pentagon centers of the fullerene surfaces is occupied by a single {sup 4}He atom. The second-layer promotion starts beyond N = 38 on both isomers, where a compressible incommensurate structure is observed on the D{sub 6h} isomer and another commensurate structure on D{sub 2d}. Between N = 20 and N = 38, the {sup 4}He monolayer on D{sub 6h} shows several distinct rings of delocalized {sup 4}He atoms along with strongly anisotropic superfluid responses at low temperatures, while isotropic but weak superfluid responses are observed in the {sup 4}He layer on D{sub 2d}.

  16. Anisotropic superfluidity of (4)He on a C36 fullerene molecule.

    PubMed

    Park, Sungjin; Kim, Byeongjoon; Kwon, Yongkyung

    2015-09-14

    We have performed path-integral Monte Carlo calculations to study the adsorption of (4)He atoms on two different C36 isomers with the D6h and the D2d symmetries. The radial (4)He density distributions reveal layer-by-layer growth with the first layer being located at a distance of ∼5.5 Å from the C36 molecular center and the second layer at ∼8.3 Å. From the angular density profiles of (4)He, we find different quantum states as the number of (4)He adatoms N varies. For N = 20, we observe commensurate solid structures on both D6h and D2d isomers, where each of 8 hexagon and 12 pentagon centers of the fullerene surfaces is occupied by a single (4)He atom. The second-layer promotion starts beyond N = 38 on both isomers, where a compressible incommensurate structure is observed on the D6h isomer and another commensurate structure on D2d. Between N = 20 and N = 38, the (4)He monolayer on D6h shows several distinct rings of delocalized (4)He atoms along with strongly anisotropic superfluid responses at low temperatures, while isotropic but weak superfluid responses are observed in the (4)He layer on D2d. PMID:26374039

  17. 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

  18. {sup 4}He adsorption and superfluid transition on C{sub 60}

    SciTech Connect

    Teizer, W.; Hallock, R.B.; Hebard, A.F.

    1997-10-01

    The authors present adsorption isotherm data of {sup 4}He on C{sub 60} for 1.50 K < T < 1.68 K determined by measurements of the frequency of quartz crystal microbalances (QCM`s) coated with C{sub 60} films. They find a Kosterlitz-Thouless transition with a jump in the areal superfluid density close to predictions. By comparing the adsorbed {sup 4}He on two QCM`s they derive an upper limit for the amount of {sup 4}He intercalated into C{sup 60} at low temperature of 0.05 {sup 4}He atoms per C{sub 60} molecule. The low coverage portion of the adsorption data shows an apparent excess adsorption of {sup 4}He onto the C{sub 60}.

  19. Ab initio many-body calculations of the (3)H(d,n)(4)He and (3)He(d,p)(4)He fusion reactions.

    PubMed

    Navrátil, Petr; Quaglioni, Sofia

    2012-01-27

    We apply the ab initio no-core shell model combined with the resonating-group method approach to calculate the cross sections of the (3)H(d,n)(4)He and (3)He(d,p)(4)He fusion reactions. These are important reactions for the big bang nucleosynthesis and the future of energy generation on Earth. Starting from a selected similarity-transformed chiral nucleon-nucleon interaction that accurately describes two-nucleon data, we performed many-body calculations that predict the S factor of both reactions. Virtual three-body breakup effects are obtained by including excited pseudostates of the deuteron in the calculation. Our results are in satisfactory agreement with experimental data and pave the way for microscopic investigations of polarization and electron-screening effects, of the (3)H(d,γn)(4)He bremsstrahlung and other reactions relevant to fusion research. PMID:22400830

  20. Isovector dipole resonances in {sup 4}He and neutrino-heating in supernova

    SciTech Connect

    Nakayama, S.; Matsumoto, E.; Fushimi, K.; Hayami, R.; Suzuki, T.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Fujiwara, M.; Hashimoto, H.; Kawase, K.; Nakanishi, K.; Oota, T.; Yosoi, M.; Greenfield, M. B.; Kudoh, T.; Sagara, K.; Tanaka, M.

    2010-06-01

    We studied transition strengths to isovector dipole resonances (GDR-1-bar , SDR-1-bar , and SDR-2-bar ) in {sup 4}He by using the {sup 4}He({sup 7}Li,{sup 7}Begamma) reaction at 455 MeV and by comparing with shell-model calculations, in order to estimate cross sections of {sup 4}He for reactions induced by neutrinos emitting from a thermalized neutrino-sphere in the type-II supernova. Excitation of the SDR was dominant in the neutrino-heating of {sup 4}He. The {sup 4}He-excitation via neutral-current reactions of nu{sub m}u{sub ,t}au and nu-bar{sub m}u{sub ,t}au was found to be one order of magnitude stronger than that via charged-current reactions of nu{sub e} and nu-bar{sub e}. The total energy-weighted cross section {sub N} for neutrino-induced neutral-current reactions on {sup 4}He was found to amount to about 1.0x10{sup -40} MeVcentre dotcm{sup 2} which is comparable to those used in the previous simulations. The neutrino-heating effect of {sup 4}He is small in the type-II supernova explosion.

  1. Radiogenic 4He as a conservative tracer in buried-valley aquifers

    USGS Publications Warehouse

    Van Der Hoven, S. J.; Wright, R.E.; Carstens, D.A.; Hackley, Keith C.

    2005-01-01

    [1] The accumulation of 4He in groundwater can be a powerful tool in hydrogeologic investigations. However, the use of 4He often suffers from disagreement or uncertainty related to in situ and external sources of 4He. In situ sources are quantified by several methods, while external sources are often treated as calibration parameters in modeling. We present data from direct laboratory measurements of 4He release from sediments and field data of dissolved 4He in the Mahomet Aquifer, a well-studied buried-valley aquifer in central Illinois. The laboratory-derived accumulation rates (0.13-0.91 ??cm3 STP kgwater-1 yr-1) are 1-2 orders of magnitude greater than the accumulation rates based on the U and Th concentrations of the sediments (0.004-0.009 ??cm3 STP kgwater-1 yr -1). The direct measurement of accumulation rates are more consistent with dissolved concentrations of 4He in the groundwater. We suggest that the direct measurement method is applicable in a variety of hydrogeologic settings. The patterns of accumulation of 4He are consistent with the conceptual model of flow in the aquifer based on hydraulic and geochemical evidence and show areas where in situ production and external sources of 4He are dominant. In the southwestern part of the study area, Ne concentrations are less than atmospheric solubility, indicating gases have been lost from the groundwater. Available evidence indicates that the gases are lost as groundwater passes by pockets of CH4 in glacial deposits overlying the aquifer. However, the external flux from the underlying bedrock appears to dominate the accumulation of radiogenic 4He in the aquifer in the southwestern part of the study area, and the loss or gain of helium as groundwater passes through the overlying sediments is minor in comparison. Copyright 2005 by the American Geophysical Union.

  2. Interlayer correlation between two 4He monolayers adsorbed on both sides of α -graphyne

    NASA Astrophysics Data System (ADS)

    Ahn, Jeonghwan; Park, Sungjin; Lee, Hoonkyung; Kwon, Yongkyung

    2015-07-01

    Path-integral Monte Carlo calculations have been performed to study the 4He adsorption on both sides of a single α -graphyne sheet. For investigation of the interlayer correlation between the upper and the lower monolayers of 4He adatoms, the 4He-substrate interaction is described by the sum of the 4He-C interatomic pair potentials for which we use both Lennard-Jones and Yukawa-6 anisotropic potentials. When the lower 4He layer is a C4 /3 commensurate solid, the upper-layer 4He atoms are found to form a kagome lattice structure at a Mott-insulating density of 0.0706 Å-2 and a commensurate solid at an areal density of 0.0941 Å-2 for both substrate potentials. The correlation between upper- and lower-layer pseudospins, which were introduced in Kwon et al. [Phys. Rev. B 88, 201403(R) (2013)], 10.1103/PhysRevB.88.201403 for two degenerate configurations of three 4He atoms in a hexagonal cell, depends on the substrate potential used; with the substrate potential based on the anisotropic Yukawa-6 pair potentials, the Ising pseudospins of both 4He layers are found to be antiparallel to each other whereas the parallel and antiparallel pseudospin alignments between the two 4He layers are nearly degenerate with the Lennard-Jones potentials. This is attributed to the difference in the interlayer distance, which is ˜4 Å with the Yukawa-6 substrate potential but as large as ˜4.8 Å with the Lennard-Jones potential.

  3. Viscosity of liquid {sup 4}He and quantum of circulation: Are they related?

    SciTech Connect

    L’vov, Victor S. E-mail: skrbek@fzu.cz; Skrbek, Ladislav E-mail: skrbek@fzu.cz; Sreenivasan, Katepalli R. E-mail: skrbek@fzu.cz

    2014-04-15

    In the vicinity of the superfluid transition in liquid {sup 4}He, we explore the relation between two apparently unrelated physical quantities—the kinematic viscosity, ν, in the normal state and the quantum of circulation, κ, in the superfluid state. The model developed here leads to the simple relationship ν ≈ κ/6, and links the classical and quantum flow properties of liquid {sup 4}He. We critically examine available data relevant to this relation and find that the prediction holds well at the saturated vapor pressure. Additionally, we predict the kinematic viscosity for liquid {sup 4}He along the λ-line at negative pressures.

  4. Comment on ''Few-atom /sup 3/He--/sup 4/He mixed molecules''

    SciTech Connect

    Harada, M.

    1983-02-15

    It is pointed out that a recent work by Nakaichi et al. on few-atom /sup 3/He--/sup 4/He mixed molecules is based on incorrect values of THETA/sup 2//M/sub 3/ and THETA/sup 2//M/sub 4/, where M/sub 3/ and M/sub 4/ are the masses of the /sup 3/He and /sup 4/He atoms. This is shown to affect their conclusion on the /sup 3/He(/sup 4/He)/sub 2/ system seriously.

  5. 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.

  6. Unusual Doppler effect in superfluid and nonanalyticity of {sup 4}He-{sup 3}He hydrodynamics

    SciTech Connect

    Nepomnyashchy, Y.A.; Gov, N.; Mann, A.

    1995-08-01

    The authors investigate the influence of {sup 3}He admixture on the Doppler shift of different sounds in superfluid {sup 4}He with internal motion. This influence proves to be very strong in the whole region of the nontrivial temperature behavior of the Doppler shift and implies in particular an unexpected amplification of certain Doppler anomalies. They explain origin of the features of the internal Doppler effect in pure {sup 4}He and {sup 4}He-{sup 3}He mixture and notice an interesting peculiarity of the {sup 4}He-{sup 3}He two-fluid hydrodynamics: its nonanalyticity at low temperature and small {sup 3}He concentration: T{yields}0, X{yields}0.

  7. New Phenomenon of the Hysteresis of 4He in Vycor Glass

    NASA Astrophysics Data System (ADS)

    Jin, Xin; Xu, Xiaonong; Yan, Yong; A, L. Thomson; D, F. Brewer; S, Haynes; N, Sharma

    1992-02-01

    The low temperature part of hysteresis curves of the freezing and melting processes of 4He in vycor glass with the lowest temperature 0.4K were measured, as the pressure ranged from 36.45 to 55.18 (105 Pa). Some novel characteristics of these curves were observed in such high temperature and pressure range. They may result from the existence of superfluid 4He.

  8. Resonances in (11)C observed in the (4)He((7)Be, alpha)(7)Be and (4)He((7)Be, p)(10)B reactions

    SciTech Connect

    Freer, M.; Ashwood, N. I.; Curtis, N.; Malcolm, J.; Munoz-Britton, T.; Price, D.; Wheldon, C.; Achouri, N. L.; Demaret, P.; Bardayan, Daniel W; Pain, Steven D; Brown, S.; Catford, W.; Harlin, Christopher W; Thomas, J. S.; Wilson, G.; Chipps, K.; Milin, M.; Raabe, R.; Soic, N.

    2012-01-01

    Measurements of the {sup 4}He({sup 7}Be,{alpha}){sup 7}Be and {sup 4}He({sup 7}Be,p){sup 10}B reactions were performed using {sup 7}Be beam energies of 7.1 and 23 MeV and a helium-4 target, employing the thick target technique. Resonances were observed between E{sub x}({sup 11}C) = 8.6 to 13.8 MeV. An R-matrix analysis was performed to characterize the spins and partial widths. This analysis showed that the observed sequence of states was consistent with that found for {sup 7}Li + {alpha} resonant scattering populating resonances in {sup 11}B. A comparison of the proposed partial widths for decay with the Wigner limit indicates that several of the states are associated with cluster-like structures.

  9. Ab Initio Many-Body Calculations Of n-3H, n-4He, p-3,4He, And n-10Be Scattering

    SciTech Connect

    Quaglioni, S; Navratil, P

    2008-03-26

    We develop a new ab initio many-body approach capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group method with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters. This approach preserves translational symmetry and Pauli principle. We present phase shifts for neutron scattering on {sup 3}H, {sup 4}He and {sup 10}Be and proton scattering on {sup 3,4}He, using realistic nucleon-nucleon potentials. Our A = 4 scattering results are compared to earlier ab initio calculations. We demonstrate that a proper treatment of the coupling to the n-{sup 10}Be continuum is essential to explain the parity-inverted ground state in {sup 11}Be.

  10. New light on the intriguing history of superfluidity in liquid (4)He.

    PubMed

    Griffin, Allan

    2009-04-22

    Surprisingly, it was 30 years after the first liquefaction of (4)He in 1908 that the discovery that liquid (4)He is not just a 'cold' liquid was made. Below T = 2.18 K, it is a 'quantum' liquid which exhibits spectacular macroscopic quantum behaviour that can be seen with the naked eye. Since the observation of superfluidity in liquid (4)He is one of the greatest discoveries in modern physics, we present a day-to-day chronology of the tangled events which preceded the seminal discovery of zero viscosity in 1938 by Kapitza in Moscow and by Allen and Misener in Cambridge. On the theory side, London argued in 1938 that the microscopic basis for this new superfluid phase was the forgotten phenomenon of Bose-Einstein condensation (BEC) first suggested by Einstein in 1925. In 1941, Landau developed a very successful theory of superfluid (4)He, but it was not anchored in a microscopic theory of interacting atoms. It took another 20 years for theorists to unify the two seemingly different theories of Landau and London. Experiments on trapped superfluid atomic gases since 1995 have shone new light on superfluid (4)He. In the mid-1930s, London had emphasized that superconductivity in metals and superfluidity in liquid (4)He were similar. Experiments on trapped two-component Fermi gases in the last five years have shown that a Bose condensate is indeed the basis of both of these superfluid phases. This confirms the now famous Bardeen-Cooper-Schrieffer-BEC crossover scenario developed for superfluidity by Leggett and Nozières in the early 1980s but largely ignored until a few years ago. The study of superfluid (4)He will increasingly overlap with strongly interacting dilute quantum gases, perhaps opening up a new era of research on this most amazing liquid.

  11. New light on the intriguing history of superfluidity in liquid 4He

    NASA Astrophysics Data System (ADS)

    Griffin, Allan

    2009-04-01

    Surprisingly, it was 30 years after the first liquefaction of 4He in 1908 that the discovery that liquid 4He is not just a 'cold' liquid was made. Below T = 2.18 K, it is a 'quantum' liquid which exhibits spectacular macroscopic quantum behaviour that can be seen with the naked eye. Since the observation of superfluidity in liquid 4He is one of the greatest discoveries in modern physics, we present a day-to-day chronology of the tangled events which preceded the seminal discovery of zero viscosity in 1938 by Kapitza in Moscow and by Allen and Misener in Cambridge. On the theory side, London argued in 1938 that the microscopic basis for this new superfluid phase was the forgotten phenomenon of Bose-Einstein condensation (BEC) first suggested by Einstein in 1925. In 1941, Landau developed a very successful theory of superfluid 4He, but it was not anchored in a microscopic theory of interacting atoms. It took another 20 years for theorists to unify the two seemingly different theories of Landau and London. Experiments on trapped superfluid atomic gases since 1995 have shone new light on superfluid 4He. In the mid-1930s, London had emphasized that superconductivity in metals and superfluidity in liquid 4He were similar. Experiments on trapped two-component Fermi gases in the last five years have shown that a Bose condensate is indeed the basis of both of these superfluid phases. This confirms the now famous Bardeen-Cooper-Schrieffer-BEC crossover scenario developed for superfluidity by Leggett and Nozières in the early 1980s but largely ignored until a few years ago. The study of superfluid 4He will increasingly overlap with strongly interacting dilute quantum gases, perhaps opening up a new era of research on this most amazing liquid.

  12. Mineralogy of IDPs with Known 4He and Trace Element Contents

    NASA Astrophysics Data System (ADS)

    Klock, W.; Flynn, G. J.; Sutton, S. R.; Nier, A. O.

    1992-07-01

    Interplanetary Dust Particles (IDPs) collected in the atmosphere are a very special source of information about solar system objects like asteroids and comets. Suggested IDP properties indicative of their origins include amounts of 4He and 4He release temperatures (Nier and Schlutter 1990, 1992), solar flare track densities (Sandford and Bradley 1989), and trace element abundances (Flynn et al. 1992). Recently Flynn et al. (1992) suggested that Zn depletions of IDPs are indicative of heating in the atmosphere. On the average, asteroidal particles experience less heating than cometary particles (Flynn 1989). Nier and Schlutter (1992) showed that 4He release temperatures of individual IDPs vary from 420 C up to more than 800 C. Presently it is not clear if variations of 4He contents are a result of the original mineral compositions, and therefore source of individual IDPs, or if they are mainly affected by atmospheric entry heating. We studied the mineralogy of IDPs having variable amounts of 4He. Some of the particles were analyzed by SXRF for volatile trace elements. The particles in Table 1 are ordered according to their amount of 4He. High 4He contents (>11.0 x 1O^-11 cm^3) are found among particles characterized by their porous texture and occurrence of unequilibrated mineral phases. Particles of this group contain abundant glass, solar flare tracks are preserved and have chondritic Zn abundances. Among the 13 particles having low 4He contents six particles contain magnetite crystals that formed by atmospheric entry heating. Three magnetite-bearing particles are low in Zn. Though high in Zn, due to a Zn-bearing iron-sulfide in the center, L2005C19 is a heated particle. L2005A8 is texturally similar to other heated particles, but magnetites were so far not identified. According to Rietmeijer and Mackinnon (1985), particle W7029*A was not heated above 315 C and this explains its chondritic Zn level at a low amount of 4He. Three hydrated IDPs have low 4He contents

  13. Control of the wetting properties of 4He crystals in superfluid

    NASA Astrophysics Data System (ADS)

    Takahashi, T.; Minezaki, H.; Suzuki, A.; Obara, K.; Itaka, K.; Nomura, R.; Okuda, Y.

    2016-05-01

    To investigate whether it is possible to control the wetting of 4He crystals on a wall in superfluid, the contact angles of 4He crystals were measured on rough and smooth walls at very low temperatures. A rough wall was prepared in a simple manner in which a commercially available coating agent for car mirrors, which makes the glass surface superhydrophobic, was used to coat a glass plate. The contact angles of 4He crystals were increased by approximately 10° on the rough wall coated with the agent. Therefore, the increase in the repellency of 4He crystals in superfluid was demonstrated to be possible on a very rough surface. The enhancement of the contact angles and a scanning electron microscopy image of the coated surface both suggest that a Cassie-Baxter state of 4He crystals was realized on the surface; the crystals did not have full contact with the wall, but entrapped superfluid was present beneath the crystals in the hollow parts of the rough wall.

  14. Control of the wetting properties of ^{4}He crystals in superfluid.

    PubMed

    Takahashi, T; Minezaki, H; Suzuki, A; Obara, K; Itaka, K; Nomura, R; Okuda, Y

    2016-05-01

    To investigate whether it is possible to control the wetting of ^{4}He crystals on a wall in superfluid, the contact angles of ^{4}He crystals were measured on rough and smooth walls at very low temperatures. A rough wall was prepared in a simple manner in which a commercially available coating agent for car mirrors, which makes the glass surface superhydrophobic, was used to coat a glass plate. The contact angles of ^{4}He crystals were increased by approximately 10^{∘} on the rough wall coated with the agent. Therefore, the increase in the repellency of ^{4}He crystals in superfluid was demonstrated to be possible on a very rough surface. The enhancement of the contact angles and a scanning electron microscopy image of the coated surface both suggest that a Cassie-Baxter state of ^{4}He crystals was realized on the surface; the crystals did not have full contact with the wall, but entrapped superfluid was present beneath the crystals in the hollow parts of the rough wall.

  15. On the origin of (4)He and (40)Ar in natural gold

    NASA Technical Reports Server (NTRS)

    Eugster, O.; Hofmann, B.; Niedermann, S.; Thalmann, CH.

    1993-01-01

    In a first report on our investigations of noble gases in native gold we demonstrated that placer gold contains an excess of radiogenic (4)He and (40)Ar relative to the concentrations expected from in situ decay of U, Th, and K, respectively, during the geologic age of about 30 Ma of the samples. We also showed that the U/Th-(4)He age of 36 Ma of vein-type gold from the Southern Alps agrees with its K-Ar formation age derived from associated muscovite and biotite. We now studied the question of the origin of the (4)He and (40)Ar excesses of placer gold. We conclude that gold contains two components of noble gases, a low-temperature component from fluid inclusions or phases which release noble gases at less than 800 C and a high-temperature component released when gold melts (1064 C). In some samples extremely high U and K concentrations or an unreasonably high formation age would be required to explain the observed (4)He abundances. Thus, trapped (4)He and (40)Ar must be present in gold.

  16. Green's function theory for the Cheng-Schick model of 3He-4He mixtures

    NASA Astrophysics Data System (ADS)

    Siemann, R. P.; Boukahil, A.; Huber, D. L.

    2014-08-01

    In this paper, we outline a theory for the thermodynamic properties of 3He-4He mixtures in the neighborhood of the critical line and the tricritical point (TCP). The theory utilizes the Cheng-Schick (CS) lattice gas model where both the 3He and 4He atoms are treated as quantum particles on a lattice. The analysis is based on Green's function approach. Results are presented for the ordering susceptibility and the thermal averages of the occupation numbers of 3He and 4He atoms. We derive a self-consistent equation for the ordering susceptibility and use it to calculate the critical line and locate the TCP. Our findings are compared with the predictions obtained from high temperature series expansions, mean field theory and the random phase approximation (RPA).

  17. Upper bound on parity-violating neutron spin rotation in {sup 4}He

    SciTech Connect

    Snow, W. M.; Luo, D.; Walbridge, S. B.; Crawford, B. E.; Gan, K.; Micherdzinska, A. M.; Opper, A. K.; Heckel, B. R.; Swanson, H. E.; Sharapov, E. I.; Zhumabekova, V.

    2011-02-15

    We report an upper bound on parity-violating neutron spin rotation in {sup 4}He. This experiment is the most sensitive search for neutron-weak optical activity yet performed and represents a significant advance in precision in comparison to past measurements in heavy nuclei. The experiment was performed at the NG-6 slow-neutron beamline at the National Institute of Standards and Technology (NIST) Center for Neutron Research. Our result for the neutron spin rotation angle per unit length in {sup 4}He is d{phi}/dz=[+1.7{+-}9.1(stat.){+-}1.4(sys.)]x10{sup -7} rad/m. The statistical uncertainty is smaller than current estimates of the range of possible values of d{phi}/dz in n+{sup 4}He.

  18. Extracting the spectral function of 4He from a relativistic plane-wave treatment

    NASA Astrophysics Data System (ADS)

    Abu-Raddad, L. J.; Piekarewicz, J.

    2001-12-01

    The spectral function of 4He is extracted from a plane-wave approximation to the (e,e'p) reaction using a fully relativistic formalism. We take advantage of both an algebraic ``trick'' and a general relativistic formalism for quasifree processes developed earlier to arrive at transparent, analytical expressions for all quasifree (e,e'p) observables. An observable is identified for the clean and model-independent extraction of the spectral function. Our simple relativistic plane-wave calculations provide baseline predictions for the recently measured, but not yet fully analyzed, momentum distribution of 4He by the A1 Collaboration from Mainz. Yet in spite of its simplicity, our approach predicts momentum distributions for 4He that rival some of the best nonrelativistic calculations to date. Finally, we highlight some of the challenges and opportunities that remain, both theoretically and experimentally, in the extraction of quasifree observables.

  19. Calibration Technique for Superfluid 4He Weak-Link Cells Based on the Fountain Effect

    SciTech Connect

    Hoskinson, E.; Packard, R. E.

    2006-09-07

    Studies of superfluid 4He weak-links require calibration constants which permit the determination of the pressure and temperature differences which drive Josephson oscillations. We describe a technique for calibrating 4He weak-link cells in which a heater is used to induce fountain pressures detected by the deflection of a diaphragm. The technique determines the diaphragm spring constant, the inner cell volume, and the thermal conductance of the inner cells walls. This information is used to convert the measured deflection of the diaphragm into the total chemical potential difference across the weak link.

  20. JLab measurement of the 4He charge form factor at large momentum transfers.

    PubMed

    Camsonne, A; Katramatou, A T; Olson, M; Sparveris, N; Acha, A; Allada, K; Anderson, B D; Arrington, J; Baldwin, A; Chen, J-P; Choi, S; Chudakov, E; Cisbani, E; Craver, B; Decowski, P; Dutta, C; Folts, E; Frullani, S; Garibaldi, F; Gilman, R; Gomez, J; Hahn, B; Hansen, J-O; Higinbotham, D W; Holmstrom, T; Huang, J; Iodice, M; Jiang, X; Kelleher, A; Khrosinkova, E; Kievsky, A; Kuchina, E; Kumbartzki, G; Lee, B; LeRose, J J; Lindgren, R A; Lott, G; Lu, H; Marcucci, L E; Margaziotis, D J; Markowitz, P; Marrone, S; Meekins, D; Meziani, Z-E; Michaels, R; Moffit, B; Norum, B; Petratos, G G; Puckett, A; Qian, X; Rondon, O; Saha, A; Sawatzky, B; Segal, J; Shabestari, M; Shahinyan, A; Solvignon, P; Subedi, R R; Suleiman, R; Sulkosky, V; Urciuoli, G M; Viviani, M; Wang, Y; Wojtsekhowski, B B; Yan, X; Yao, H; Zhang, W-M; Zheng, X; Zhu, L

    2014-04-01

    The charge form factor of 4He has been extracted in the range 29  fm(-2) ≤ Q2 ≤ 77  fm(-2) from elastic electron scattering, detecting 4He recoil nuclei and electrons in coincidence with the high resolution spectrometers of the Hall A Facility of Jefferson Lab. The measurements have uncovered a second diffraction minimum for the form factor, which was predicted in the Q2 range of this experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the few-body problem. PMID:24745410

  1. Using the surface tension to estimate the condensate density of superfluid /sup 4/He

    SciTech Connect

    Campbell, L.J.

    1983-01-01

    Distortion of the condensate wavefunction at the free surface of superfluid /sup 4/He contributes to the surface tension in proportion to the condensate fraction n/sub 0/(T). Using this to resolve the present discrepancy between the measured and predicted temperature dependencies of the surface tension gives n/sub 0/(T) in good agreement with results from neutron and x-ray scattering measurements. This picture is also consistent with the measured /sup 3/He-/sup 4/He interfacial tension.

  2. Equilibrium shape of 4He crystal under zero gravity below 200 mK

    PubMed Central

    Takahashi, Takuya; Ohuchi, Haruka; Nomura, Ryuji; Okuda, Yuichi

    2015-01-01

    Equilibrium crystal shape is the lowest energy crystal shape that is hardly realized in ordinary crystals because of their slow relaxation. 4He quantum crystals in a superfluid have been expected as unique exceptions that grow extremely fast at very low temperatures. However, on the ground, gravity considerably deforms the crystals and conceals the equilibrium crystal shape, and thus, gravity-free environment is needed to observe the equilibrium shape of 4He. We report the relaxation processes of macroscopic 4He crystals in a superfluid below 200 mK under zero gravity using a parabolic flight of a jet plane. When gravity was removed from a gravity-flattened 4He crystal, the crystal rapidly transformed into a shape with flat surfaces. Although the relaxation processes were highly dependent on the initial condition, the crystals relaxed to a nearly homothetic shape in the end, indicating that they were truly in an equilibrium shape minimizing the interfacial free energy. Thanks to the equilibrium shape, we were able to determine the Wulff’s origin and the size of the c-facet together with the vicinal surface profile next to the c-facet. The c-facet size was extremely small in the quantum crystals, and the facet-like flat surfaces were found to be the vicinal surfaces. At the same time, the interfacial free energy of the a-facet and s-facet was also obtained. PMID:26601315

  3. ^4He Crystals in Reduced Gravity Obtained by Parabolic Flights of a Jet Plane

    NASA Astrophysics Data System (ADS)

    Takahashi, Takuya; Nomura, Ryuji; Okuda, Yuichi

    2016-11-01

    ^4He crystals usually sink to the bottom of the container in a superfluid and are deformed into a flat shape by gravity when their size is much larger than the capillary length of 1 mm. When gravity is reduced to zero, the capillary length diverges and the gravity-flattened crystals are expected to relax into an equilibrium crystal shape determined by the interfacial free energy at low enough temperatures where the relaxation time is very short. We performed a reduced gravity experiment on ^4He crystals at ultralow temperatures by developing a specially designed ^3He-^4He dilution refrigerator compatible with the experimental restrictions in a small jet plane. ^4He crystals relaxed to the equilibrium crystal shape below 600 mK during a reduced gravity period of 20 s produced by a parabolic flight. The equilibrium crystal shape, however, was metastable in most cases, governed by the boundary conditions imposed by the wall. Utilizing acoustic radiation pressure, we deformed the crystal enough to allow it to escape from the metastable shape below 150 mK. After this large deformation, the crystal relaxed to a shape completely different from its initial shape, showing three types of facets, viz., c-, a-, and s-facets, which was concluded to be the lowest energy equilibrium shape.

  4. Phase-space analysis of convection in a /sup 3/He - superfluid /sup 4/He solution

    SciTech Connect

    Haucke, H.; Maeno, Y.

    1982-01-01

    Observations have been made on thermal convection below 1K in a dilute solution of /sup 3/He in superfluid /sup 4/He contained in a cylindrical cell of aspect ratio GAMMA = 1.20. Complicated oscillatory phenomena were observed with a high degree of reproducibility using two temperature sensors. Phase-space analysis suggests a description in terms of strange-attractor dynamics.

  5. 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.

  6. Equilibrium shape of (4)He crystal under zero gravity below 200 mK.

    PubMed

    Takahashi, Takuya; Ohuchi, Haruka; Nomura, Ryuji; Okuda, Yuichi

    2015-10-01

    Equilibrium crystal shape is the lowest energy crystal shape that is hardly realized in ordinary crystals because of their slow relaxation. (4)He quantum crystals in a superfluid have been expected as unique exceptions that grow extremely fast at very low temperatures. However, on the ground, gravity considerably deforms the crystals and conceals the equilibrium crystal shape, and thus, gravity-free environment is needed to observe the equilibrium shape of (4)He. We report the relaxation processes of macroscopic (4)He crystals in a superfluid below 200 mK under zero gravity using a parabolic flight of a jet plane. When gravity was removed from a gravity-flattened (4)He crystal, the crystal rapidly transformed into a shape with flat surfaces. Although the relaxation processes were highly dependent on the initial condition, the crystals relaxed to a nearly homothetic shape in the end, indicating that they were truly in an equilibrium shape minimizing the interfacial free energy. Thanks to the equilibrium shape, we were able to determine the Wulff's origin and the size of the c-facet together with the vicinal surface profile next to the c-facet. The c-facet size was extremely small in the quantum crystals, and the facet-like flat surfaces were found to be the vicinal surfaces. At the same time, the interfacial free energy of the a-facet and s-facet was also obtained.

  7. Lieb-Liniger-like model of quantum solvation in CO-(4)HeN clusters.

    PubMed

    Farrelly, D; Iñarrea, M; Lanchares, V; Salas, J P

    2016-05-28

    Small (4)He clusters doped with various molecules allow for the study of "quantum solvation" as a function of cluster size. A peculiarity of quantum solvation is that, as the number of (4)He atoms is increased from N = 1, the solvent appears to decouple from the molecule which, in turn, appears to undergo free rotation. This is generally taken to signify the onset of "microscopic superfluidity." Currently, little is known about the quantum mechanics of the decoupling mechanism, mainly because the system is a quantum (N + 1)-body problem in three dimensions which makes computations difficult. Here, a one-dimensional model is studied in which the (4)He atoms are confined to revolve on a ring and encircle a rotating CO molecule. The Lanczos algorithm is used to investigate the eigenvalue spectrum as the number of (4)He atoms is varied. Substantial solvent decoupling is observed for as few as N = 5 (4)He atoms. Examination of the Hamiltonian matrix, which has an almost block diagonal structure, reveals increasingly weak inter-block (solvent-molecule) coupling as the number of (4)He atoms is increased. In the absence of a dopant molecule the system is similar to a Lieb-Liniger (LL) gas and we find a relatively rapid transition to the LL limit as N is increased. In essence, the molecule initially-for very small N-provides a central, if relatively weak, attraction to organize the cluster; as more (4)He atoms are added, the repulsive interactions between the identical bosons start to dominate as the solvation ring (shell) becomes more crowded which causes the molecule to start to decouple. For low N, the molecule pins the atoms in place relative to itself; as N increases the atom-atom repulsion starts to dominate the Hamiltonian and the molecule decouples. We conclude that, while the notion of superfluidity is a useful and correct description of the decoupling process, a molecular viewpoint provides complementary insights into the quantum mechanism of the transition from a

  8. Lieb-Liniger-like model of quantum solvation in CO-4HeN clusters

    NASA Astrophysics Data System (ADS)

    Farrelly, D.; Iñarrea, M.; Lanchares, V.; Salas, J. P.

    2016-05-01

    Small 4He clusters doped with various molecules allow for the study of "quantum solvation" as a function of cluster size. A peculiarity of quantum solvation is that, as the number of 4He atoms is increased from N = 1, the solvent appears to decouple from the molecule which, in turn, appears to undergo free rotation. This is generally taken to signify the onset of "microscopic superfluidity." Currently, little is known about the quantum mechanics of the decoupling mechanism, mainly because the system is a quantum (N + 1)-body problem in three dimensions which makes computations difficult. Here, a one-dimensional model is studied in which the 4He atoms are confined to revolve on a ring and encircle a rotating CO molecule. The Lanczos algorithm is used to investigate the eigenvalue spectrum as the number of 4He atoms is varied. Substantial solvent decoupling is observed for as few as N = 5 4He atoms. Examination of the Hamiltonian matrix, which has an almost block diagonal structure, reveals increasingly weak inter-block (solvent-molecule) coupling as the number of 4He atoms is increased. In the absence of a dopant molecule the system is similar to a Lieb-Liniger (LL) gas and we find a relatively rapid transition to the LL limit as N is increased. In essence, the molecule initially—for very small N—provides a central, if relatively weak, attraction to organize the cluster; as more 4He atoms are added, the repulsive interactions between the identical bosons start to dominate as the solvation ring (shell) becomes more crowded which causes the molecule to start to decouple. For low N, the molecule pins the atoms in place relative to itself; as N increases the atom-atom repulsion starts to dominate the Hamiltonian and the molecule decouples. We conclude that, while the notion of superfluidity is a useful and correct description of the decoupling process, a molecular viewpoint provides complementary insights into the quantum mechanism of the transition from a molecular

  9. Lieb-Liniger-like model of quantum solvation in CO-(4)HeN clusters.

    PubMed

    Farrelly, D; Iñarrea, M; Lanchares, V; Salas, J P

    2016-05-28

    Small (4)He clusters doped with various molecules allow for the study of "quantum solvation" as a function of cluster size. A peculiarity of quantum solvation is that, as the number of (4)He atoms is increased from N = 1, the solvent appears to decouple from the molecule which, in turn, appears to undergo free rotation. This is generally taken to signify the onset of "microscopic superfluidity." Currently, little is known about the quantum mechanics of the decoupling mechanism, mainly because the system is a quantum (N + 1)-body problem in three dimensions which makes computations difficult. Here, a one-dimensional model is studied in which the (4)He atoms are confined to revolve on a ring and encircle a rotating CO molecule. The Lanczos algorithm is used to investigate the eigenvalue spectrum as the number of (4)He atoms is varied. Substantial solvent decoupling is observed for as few as N = 5 (4)He atoms. Examination of the Hamiltonian matrix, which has an almost block diagonal structure, reveals increasingly weak inter-block (solvent-molecule) coupling as the number of (4)He atoms is increased. In the absence of a dopant molecule the system is similar to a Lieb-Liniger (LL) gas and we find a relatively rapid transition to the LL limit as N is increased. In essence, the molecule initially-for very small N-provides a central, if relatively weak, attraction to organize the cluster; as more (4)He atoms are added, the repulsive interactions between the identical bosons start to dominate as the solvation ring (shell) becomes more crowded which causes the molecule to start to decouple. For low N, the molecule pins the atoms in place relative to itself; as N increases the atom-atom repulsion starts to dominate the Hamiltonian and the molecule decouples. We conclude that, while the notion of superfluidity is a useful and correct description of the decoupling process, a molecular viewpoint provides complementary insights into the quantum mechanism of the transition from a

  10. Search for supersolidity in solid 4He using multiple-mode torsional oscillators

    NASA Astrophysics Data System (ADS)

    Eyal, Anna; Mi, Xiao; Talanov, Artem V.; Reppy, John D.

    2016-06-01

    In 2004, Kim and Chan (KC) reported a decrease in the period of torsional oscillators (TO) containing samples of solid 4He, as the temperature was lowered below 0.2 K [Kim E, Chan MHW (2004) Science 305(5692):1941-1944]. These unexpected results constituted the first experimental evidence that the long-predicted supersolid state of solid 4He may exist in nature. The KC results were quickly confirmed in a number of other laboratories and created great excitement in the low-temperature condensed-matter community. Since that time, however, it has become clear that the period shifts seen in the early experiments can in large part be explained by an increase in the shear modulus of the 4He solid identified by Day and Beamish [Day J, Beamish J (2007) Nature 450(7171):853-856]. Using multiple-frequency torsional oscillators, we can separate frequency-dependent period shifts arising from changes in the elastic properties of the solid 4He from possible supersolid signals, which are expected to be independent of frequency. We find in our measurements that as the temperature is lowered below 0.2 K, a clear frequency-dependent contribution to the period shift arising from changes in the 4He elastic properties is always present. For all of the cells reported in this paper, however, there is always an additional small frequency-independent contribution to the total period shift, such as would be expected in the case of a transition to a supersolid state.

  11. Search for supersolidity in solid 4He using multiple-mode torsional oscillators

    NASA Astrophysics Data System (ADS)

    Eyal, Anna; Mi, Xiao; Talanov, Artem V.; Reppy, John D.

    2016-06-01

    In 2004, Kim and Chan (KC) reported a decrease in the period of torsional oscillators (TO) containing samples of solid 4He, as the temperature was lowered below 0.2 K [Kim E, Chan MHW (2004) Science 305(5692):1941–1944]. These unexpected results constituted the first experimental evidence that the long-predicted supersolid state of solid 4He may exist in nature. The KC results were quickly confirmed in a number of other laboratories and created great excitement in the low-temperature condensed-matter community. Since that time, however, it has become clear that the period shifts seen in the early experiments can in large part be explained by an increase in the shear modulus of the 4He solid identified by Day and Beamish [Day J, Beamish J (2007) Nature 450(7171):853–856]. Using multiple-frequency torsional oscillators, we can separate frequency-dependent period shifts arising from changes in the elastic properties of the solid 4He from possible supersolid signals, which are expected to be independent of frequency. We find in our measurements that as the temperature is lowered below 0.2 K, a clear frequency-dependent contribution to the period shift arising from changes in the 4He elastic properties is always present. For all of the cells reported in this paper, however, there is always an additional small frequency-independent contribution to the total period shift, such as would be expected in the case of a transition to a supersolid state.

  12. Search for supersolidity in solid 4He using multiple-mode torsional oscillators

    PubMed Central

    Eyal, Anna; Mi, Xiao; Talanov, Artem V.; Reppy, John D.

    2016-01-01

    In 2004, Kim and Chan (KC) reported a decrease in the period of torsional oscillators (TO) containing samples of solid 4He, as the temperature was lowered below 0.2 K [Kim E, Chan MHW (2004) Science 305(5692):1941–1944]. These unexpected results constituted the first experimental evidence that the long-predicted supersolid state of solid 4He may exist in nature. The KC results were quickly confirmed in a number of other laboratories and created great excitement in the low-temperature condensed-matter community. Since that time, however, it has become clear that the period shifts seen in the early experiments can in large part be explained by an increase in the shear modulus of the 4He solid identified by Day and Beamish [Day J, Beamish J (2007) Nature 450(7171):853–856]. Using multiple-frequency torsional oscillators, we can separate frequency-dependent period shifts arising from changes in the elastic properties of the solid 4He from possible supersolid signals, which are expected to be independent of frequency. We find in our measurements that as the temperature is lowered below 0.2 K, a clear frequency-dependent contribution to the period shift arising from changes in the 4He elastic properties is always present. For all of the cells reported in this paper, however, there is always an additional small frequency-independent contribution to the total period shift, such as would be expected in the case of a transition to a supersolid state. PMID:27222579

  13. Testing the U-Th/4He dating method on carbonates I. Helium diffusion

    NASA Astrophysics Data System (ADS)

    Pinti, D. L.; Ghaleb, B. G.; Sano, Y.; Blanchette, S.; Mathouchanh, E.; Takahata, N.

    2012-12-01

    Corals and other carbonates, such as speleothems, are important climatic-change proxies which need to be precisely dated for paleoclimatic reconstructions. Yet, U-Th disequilibrium method is applicable up to ca. 500 ka old carbonates. Calcite is difficult to date precisely by U-Pb method because of the low U amounts often found and difficulties in correcting for the common lead. Radiogenic 4He produced by decay of 238U and 235U incorporated into carbonates is a potential chronometer of Quaternary, and possibly Tertiary, corals and speleothems. However, several limitations exist for this method, related to the few data on the He diffusion [1] and on the alpha recoil effect in carbonate minerals. We decided to measure 4He by step heating in carbonate samples dated previously by U-Th disequilibrium: a coral (Scleractinia) from Cape Verde dated at 125 ka; a stalagmite from Patagonia dated at 128 ka; and two hydrothermal travertines from the Ziz Valley in Morocco with ages ≥ 500 ka. A one cm3 of each sample was cut by saw, crushed, washed and sieved to 80-100μm and 100-125μm fractions. Crushed samples (0.5 to 1 gram) were loaded in a vacuum crucible and 4He extracted by step heating. Previous step heating experiments on a sub-Arctic flowstone suggested that 4He is mainly released between 400 and 600°C [2]. However, the first coral sample heated at 100°C steps, showed a release pattern profile with 4He mainly released between 200 and 400°C. Measured 4He amount of 2.05 x 10-8 (±0.03% 1σ) ccSTP/g and U content of 2.7 ppm yield a U-4He age of 62.5 ka, lower than that obtained by U-Th disequilibrium. Data were not precise enough to calculate diffusion parameters using the Arrhenius diagram. The second step-heating pyrolysis of the coral using 50°C-steps indicated that all 4He is released between 250 and 350°C. The measured 4He amount was 2.27 x 10-8 (±0.04% 1σ) ccSTP/g, yielding an age of 83 ka, again lower compared to that obtained by U-Th disequilibrium. The

  14. Temperature and pressure dependence of viscosity of quantum liquid 4He according to significant structure theory

    PubMed Central

    Ryoo, Ryong; John, Mu Shik; Eyring, Henry

    1980-01-01

    Both solid-like and gas-like flow structures are considered in the calculation of viscosity of liquid 4He using the significant structure theory of liquids. The predominance of quantum mechanical zero-point motion over that arising from thermal excitation is taken into account for the solid-like motion of molecules. The viscosity of liquid 4He under its own vapor pressure calculated over its whole temperature range is in reasonably good agreement with experimental data. The pressure dependence of viscosity also was obtained. The calculation does not yield good results at high densities where the free jumping of molecules into the nearest neighboring vacancies through the kinetic zero-point motion is no longer plausible. PMID:16592856

  15. 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.

  16. Sonofusion: Heat and ^4He Created by Cavitationally Induced Loading of Metal Foils

    NASA Astrophysics Data System (ADS)

    Stringham, Roger

    2003-03-01

    Helium four was produced in a vacuum tight system and measured by mass spectrometry with no measurable accompanying radiation. This fusion product from a piezo driven, acoustic reactor forces deuterons into a metallic foil. We believe the reaction is the result of the adiabatic collapse of transient bubbles in D_2O. The collapse process forms high-density plasma jets that are further z-pinched and then implanted into the foil lattices where the DD fusion takes place. With no evidence of long range radiation, the mc^2 energy was converted to heat. The reactor gases were analyzed at levels as high as 500 ppm of ^4He, which is 100 times that found in air. The SEM, Scanning Electron Microscope, photos of target foil surfaces show evidence of violent activity identified as ejecta sites varying in size from 100 to 10000 nm in diameter. The ^4He, radiation, excess heat, and SEM measurements support the DD fusion explanation.

  17. 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.

  18. Superheat Limit of 4He and Its Quantum Deviation from Classical Behavior

    NASA Astrophysics Data System (ADS)

    Nishigaki, Kazu; Saji, Yoshiro

    1983-07-01

    The superheating of normal liquid 4He was investigated by means of continuous heating of liquid specimen in a small glass capillary over a temperature range 2.26 K to 4.88 K. The maximum superheating data obtained were compared with the prediction from the homogeneous nucleation theory and the data for various liquids in terms of the reduced coordinates. It is confirmed that the agreement between the homogeneous nucleation theory and experiment on 4He is satisfactory, and the scaled superheating depends parametrically on the quantum parameter \\varLambda*, i.e., the deviations of the data for quantum liquids from the classical behavior become pronounced as the parameter is increased.

  19. 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. PMID:23196906

  20. Studies on the response of 3He and 4He proportional counters to monoenergetic fast neutrons

    NASA Astrophysics Data System (ADS)

    Manolopoulou, M.; Fragopoulou, M.; Stoulos, S.; Koukorava, C.; Spyrou, A.; Perdikakis, G.; Hashemi-Nezhad, S. R.; Zamani, M.

    2006-06-01

    Two helium filled proportional counters ( 3He and 4He) were studied to establish the optimum operating conditions when these counters are used for fast neutron measurements, as well as to examine the linearity of the pulse height with neutron energy. The detectors were irradiated with mono-energetic neutrons in the energy range of 230 keV-22 MeV, produced via 7Li(n,p) 7Be, 2H(d,n) 3He and 3H(d,n) 4He reactions in a Tandem Van de Graff accelerator. The gamma ray contribution to the obtained pulse height distribution and the resolution of the counters as a function of shaping time constant and applied high voltage were studied.

  1. Competition between thermal fluctuations and disorder in the crystallization of 4He in aerogel.

    PubMed

    Nomura, Ryuji; Osawa, Aiko; Mimori, Tomohiro; Ueno, Ken-ichi; Kato, Haruko; Okuda, Yuichi

    2008-10-24

    The dynamical transition in the crystallization of 4He in aerogel has been investigated by direct visualization and dynamical phase diagrams have been determined. The crystal-superfluid interface in aerogel advances via creep at high temperatures and avalanches at low temperatures. The transition temperature is higher at a higher interface velocity and lower in higher porosity aerogels. The transition is due to competition between thermal fluctuations and disorder for the crystallization process. PMID:18999765

  2. Production of {sup 4}He and tritium from Be in the COBRA-1A2 irradiation

    SciTech Connect

    Greenwood, L.R.

    1998-03-01

    The production of {sup 4}He and tritium has been calculated for beryllium irradiated in the COBRA-1A2 experiment in the Experimental Breeder Reactor II. Reaction rates were based on adjusted neutron spectra determined from reactor dosimetry measurements at three different elevations in the region of the beryllium capsules. Equations are given so that gas production can be calculated for any specific capsule elevation.

  3. Anomalous 4He Observation with EPHIN on Board SOHO during 1996 and 1997

    NASA Astrophysics Data System (ADS)

    Gómez-Herrero, R.; Del Peral, L.; Rodríguez-Frías, D.; Sequeiros, J.; Gutiérrez, J.; Müller-Mellin, R.; Kunow, H.

    2003-07-01

    The analysis of the 4 He spectrum during solar quiet time periods has demonstrated that the main source is of anomalous origin. It has been determined that this anomalous component reached similar levels to the observed ones during the 1976 solar minimum, revealing the importance of the solar polarity in the particle transport inside the heliosphere. Acceleration conditions of anomalous cosmic rays in the solar wind termination shock have been obtained.

  4. Primary populations of metastable antiprotonic (4)He and (3)He atoms.

    PubMed

    Hori, M; Eades, J; Hayano, R S; Ishikawa, T; Sakaguchi, J; Tasaki, T; Widmann, E; Yamaguchi, H; Torii, H A; Juhász, B; Horváth, D; Yamazaki, T

    2002-08-26

    Initial distributions of metastable antiprotonic (4)He and (3)He atoms over principal (n) and angular momentum (l) quantum numbers have been deduced using laser spectroscopy experiments. The regions n = 37-40 and n = 35-38 in the two atoms account for almost all of the observed fractions [(3.0 +/- 0.1)% and (2.4 +/- 0.1)%] of antiprotons captured into metastable states. PMID:12190401

  5. A new method for determining the 3He/4He ratio in the local interstellar medium

    NASA Astrophysics Data System (ADS)

    Lemoine, M.; Vidal-Madjar, A.; Ferlet, R.

    1993-06-01

    We propose here an original method for estimating the 3He/4 Heratio in the local diffuse interstellar medium at a low cost from an observational point of view. The main idea is to measure the shift in radial velocity of the 4He λ537Å and λ584Å lines due to the presence of 3He in the red wing of these lines, and to compare the observed shift to the shifts obtained through numerical simulations for different 3He/4He ratios. We performed such simulations in order to reveal the efficiency of this method, using typical astrophysical conditions and instrumental parameters corresponding to the Lyman-FUSE mission. We find that this method should yield the 3He/4He ratio with a 1 σ uncertainty ˜50% at a spectral resolving power R=30 000 and a signal-to-noise ratio S/N=50. This method thus appears more adapted to a forehand estimation of the interstellar 3He/4He ratio than the standard profile fitting method, which should yield a 1 σ uncertainty of 10% at R=30 000 and S/N ≃ 290 (Hurwitz & Bowyer, t985). Finally, our method should be able to settle the evolutionary status of 3He if 3He has been significantly enhanced or depleted in the last 4.6 Gyr. Combined with the measurement of the deuterium abundance on the same line of sight (already programmed on HST), this might yield very important constraint on Big-Bang nucleosynthesis consistency.

  6. Electronically tunable fiber laser for optical pumping of {sup 3}He and {sup 4}He

    SciTech Connect

    Stephens, E.F.; Patrick, H.; Gilbert, S.L.

    1996-03-01

    We present in this paper a low threshold, highly stable, integrated fiber laser cavity that uses an electronically tunable internal Bragg grating. The fiber laser produced over 5 mW with a spectral width of about 5 GHz at 1083 nm. The laser was used to achieve 30{percent} polarization of the 2{sup 3}{ital S}{sub 1} metastable states of {sup 4}He in a weak rf discharge cell. {copyright} {ital 1996 American Institute of Physics.}

  7. Wave Turbulence in Superfluid {sup 4}He: Energy Cascades and Rogue Waves in the Laboratory

    SciTech Connect

    Efimov, V. B.; Ganshin, A. N.; McClintock, P. V. E.; Kolmakov, G. V.; Mezhov-Deglin, L. P.

    2008-11-13

    Recent work on second sound acoustic turbulence in superfluid {sup 4}He is reviewed. Observations of forward and inverse energy cascades are described. The onset of the inverse cascade occurs above a critical driving energy and it is accompanied by giant waves that constitute an acoustic analogue of the rogue waves that occasionally appear on the surface of the ocean. The theory of the phenomenon is outlined and shown to be in good agreement with the experiments.

  8. Observation of a Dislocation-Related Interfacial Friction Mechanism in Mobile Solid 4He

    NASA Astrophysics Data System (ADS)

    Eyal, Anna; Livne, Ethan; Polturak, Emil

    2016-04-01

    We report a study of the temperature and stress dependence of the friction associated with a relative motion of crystallites of solid 4He in contact with each other. A situation where such motion exists emerges spontaneously during a disordering of a single crystal contained inside an annular sample space of a torsional oscillator (TO). Under the torque applied by the oscillating walls of the TO these crystallites move relative to each other, generating measurable dissipation at their interface. We studied this friction between 0.5 and 1.8 K in solid samples grown from commercially pure 4He and from a 100 ppm 3He-4He mixture. The data were analyzed by modeling the TO as a driven harmonic oscillator. In this model, an analysis of the resonant frequency and amplitude of the TO yields the temperature dependence of the friction coefficient. By fitting the data to specific forms, we found that over our temperature range, the dominant friction mechanism associated with the interfacial motion of the crystallites results from climb of individual dislocations. The characteristic energy scale associated with this friction can be 3 or 6 K, depending on the sample. The motion of the solid in the presence of such friction can perhaps be described as the low limit of "slip-stick" motion.

  9. Phase equilibrium in a polarized saturated {sup 3}He-{sup 4}He mixture

    SciTech Connect

    Rodrigues, A.; Vermeulen, G.

    1997-07-01

    We present experimental results on the phase equilibrium of a saturated {sup 3}He-{sup 4}He mixture, which has been cooled to a temperature of 10-15 mK and polarized in a {sup 4}He circulating dilution refrigerator to a stationary polarization of 15 %, 7 times higher than the equilibrium polarization in the external field of 7 T. The pressure dependence of the polarization enhancement in the refrigerator shows that the molar susceptibilities of the concentrated and dilute phase of a saturated {sup 3}He-{sup 4}He mixture are equal at p = 2.60 {+-} 0.04 bar. This result affects the Fermi liquid parameters of the dilute phase. The osmotic pressure in the dilute phase has been measured as a function of the polarization of the coexisting concentrated phase up to 15 %. We find that the osmotic pressure at low polarization ( < 7 % ) agrees well with thermodynamics using the new Fermi liquid parameters of the dilute phase.

  10. New solar axion search using the CERN Axion Solar Telescope with 4He filling

    NASA Astrophysics Data System (ADS)

    Arik, M.; Aune, S.; Barth, K.; Belov, A.; Bräuninger, H.; Bremer, J.; Burwitz, V.; Cantatore, G.; Carmona, J. M.; Cetin, S. A.; Collar, J. I.; Da Riva, E.; Dafni, T.; Davenport, M.; Dermenev, A.; Eleftheriadis, C.; Elias, N.; Fanourakis, G.; Ferrer-Ribas, E.; Galán, J.; García, J. A.; Gardikiotis, A.; Garza, J. G.; Gazis, E. N.; Geralis, T.; Georgiopoulou, E.; Giomataris, I.; Gninenko, S.; Gómez Marzoa, M.; Hasinoff, M. D.; Hoffmann, D. H. H.; Iguaz, F. J.; Irastorza, I. G.; Jacoby, J.; Jakovčić, K.; Karuza, M.; Kavuk, M.; Krčmar, M.; Kuster, M.; Lakić, B.; Laurent, J. M.; Liolios, A.; Ljubičić, A.; Luzón, G.; Neff, S.; Niinikoski, T.; Nordt, A.; Ortega, I.; Papaevangelou, T.; Pivovaroff, M. J.; Raffelt, G.; Rodríguez, A.; Rosu, M.; Ruz, J.; Savvidis, I.; Shilon, I.; Solanki, S. K.; Stewart, L.; Tomás, A.; Vafeiadis, T.; Villar, J.; Vogel, J. K.; Yildiz, S. C.; Zioutas, K.; CAST Collaboration

    2015-07-01

    The CERN Axion Solar Telescope (CAST) searches for a →γ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. Two parallel magnet bores can be filled with helium of adjustable pressure to match the x-ray refractive mass mγ to the axion search mass ma. After the vacuum phase (2003-2004), which is optimal for ma≲0.02 eV , we used 4He in 2005-2007 to cover the mass range of 0.02-0.39 eV and 3He in 2009-2011 to scan from 0.39 to 1.17 eV. After improving the detectors and shielding, we returned to 4He in 2012 to investigate a narrow ma range around 0.2 eV ("candidate setting" of our earlier search) and 0.39-0.42 eV, the upper axion mass range reachable with 4He, to "cross the axion line" for the KSVZ model. We have improved the limit on the axion-photon coupling to ga γ<1.47 ×10-10 GeV-1 (95% C.L.), depending on the pressure settings. Since 2013, we have returned to the vacuum and aim for a significant increase in sensitivity.

  11. Active Inspection of Nuclear Materials Using {sup 4}He Scintillation Detectors

    SciTech Connect

    Davatz, G.; Howard, A.; Chandra, R.; Gendotti, U.

    2011-12-13

    The detection of fissionable materials by neutron and high-energy photon active interrogation methods is explored using {sup 4}He scintillation detectors to search for prompt and delayed neutron signature. The low electron density of {sup 4}He in addition to its pulse shape discrimination capability allows strong rejection of gamma radiation. For the detection of the prompt neutron signatures, this capability is important as the signal produced by induced fission is accompanied by intense gamma radiation. The nanosecond time resolution of {sup 4}He scintillation detectors can be used for time-of-flight measurements aimed at determining the energy of the emitted neutrons. For delayed neutron detection, the insensitivity to the low energy neutrons present from non-signal reactions is inherent. Unlike detectors requiring a moderator, this technology can easily be collimated to reduce sensitivity to neutrons from outside the field of interest. The performance of the detectors for these applications is studied using GEANT4 computer modeling, based on measured detector parameters. A comparison is made with technologies typically used for these applications, i.e. heavily shielded organic scintillators for prompt neutron detection and Cd-lined {sup 3}He neutron detectors for the detection of delayed neutrons.

  12. Capillary Condensation of Liquid 4He in Aerogel on Cooling Through {lambda} Point

    SciTech Connect

    Miyashita, W.; Yoneyama, K.; Kato, H.; Nomura, R.; Okuda, Y.

    2006-09-07

    Capillary condensation of liquid 4He in silica aerogel with a 90% porosity was investigated visually. The initial condition of the experiment was such that liquid 4He was present in the sample cell but not in the aerogel. This situation was realized by introducing the liquid into the cell at a fast rate to avoid liquefaction in the aerogel. The free surface of the liquid rose up in the cell with filling and eventually reached the bottom of the aerogel. Then, the aerogel absorbed the liquid by capillary condensation. The height of the liquid in the aerogel rose with time t roughly as t1/2 in the normal fluid phase. This behavior was consistent with the Washburn model. When the system was cooled through the {lambda} point during the condensation, the liquid height started to rise faster in the superfluid phase with a constant velocity of about 0.3 mm/sec. The dynamics of capillary condensation was strongly dependent on whether the liquid 4He was in the normal or the superfluid phase.

  13. Spin polarization effects in the /sup 3/H(d,n)/sup 4/He fusion reaction

    SciTech Connect

    Conzett, H.E.; Rioux, C.

    1985-06-01

    A recent investigation has shown that the /sup 3/H(d,n)/sup 4/He fusion reaction rate could be enhanced by a factor of 3/2 if the fusion plasma consisted of both polarized deuterons and tritons, forming exclusively the channel-spin S = 3/2, J = 3/2/sup +/ state. This result follows simply from the statistical weights of the quartet S = 3/2 and doublet S = 1/2 initial states, with the assumption of the single J = 3/2/sup +/ reaction amplitude. Since, with a small but nonzero J = 1/2/sup +/ amplitude, the maximum enhancement of the reaction occurs at the peak of the J = 3/2/sup +/ resonance, corresponding to a deuteron lab energy of 107 keV, it is of obvious interest to know what the enhancement would be at the lower energies that are typical of fusion plasmas. We are able to address this question by extending earlier calculations which gave the values of all of the spin-polarization observables at this J = 3/2/sup +/ resonance in both the /sup 3/H(d,n)/sup 4/He and the /sup 3/He(d,p)/sup 4/He reactions.

  14. On the Evolution of the Light Elements. I. D, 3He, and 4He

    NASA Astrophysics Data System (ADS)

    Fields, Brian D.

    1996-01-01

    The light elements D, 3He, 4He, and 7Li are produced in big bang nucleosynthesis and undergo changes in their abundances due to Galactic processing. Since one may observe most of these elements only in contemporary environments, knowledge of the intervening evolution is necessary for determining the observational constraints on primordial nucleosynthesis Chemical and stellar evolution model dependences in light element evolution are systematically investigated via a comparison of 1460 possible chemical evolution scenarios and a comparison of stellar nucleosynthesis yields, all of which have been selected to fit solar neighborhood C, N, 0, and Fe abundances as well as the observed local gas density and gas mass fraction. The light element evolution and solar system yields in these models are found to span a wide range, explicitly demonstrating the model dependence. The range of model dependence for D, 3He, and 4He solar abundances is calculated, and its sensitivity to the heavy element constraints is noted. The chemical evolution contribution to the uncertainty in the observed primordial light element abundances is estimated, and the effects of this uncertainty on big bang nucleosynthesis results are discussed. The predictions for the light elements are found to be correlated; the extent and physical origin of these correlations is discussed. D and 3He evolution is found to have significant model dependence; however, the dominant factor determining their solar and interstellar abundances is their primordial abundance. In addition, 3He is found to be very sensitive to the details of processing in low-mass stars. 4He yields are shown to be very model dependent. In particular, both the introduction of mass loss and the possibly very high 4He stellar yields in the poorly understood mass range of ˜8-12Msun can lead to large enhancement of 4He production and can lead to large slopes of ΔY/ΔN and ΔY/ΔO. It is found that the inclusion of secondary nitrogen leads to

  15. Precision prediction for the big-bang abundance of primordial 4He

    NASA Astrophysics Data System (ADS)

    Lopez, Robert E.; Turner, Michael S.

    1999-05-01

    Within the standard models of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of 4He to a theoretical uncertainty of less than 0.1% (δYP<+/-0.0002), improving the current theoretical precision by a factor of 10. At this accuracy the uncertainty in the abundance is dominated by the experimental uncertainty in the neutron mean lifetime, τn=885.4+/-2.0 sec. The following physical effects were included in the calculation: the zero and finite-temperature radiative, Coulomb and finite-nucleon-mass corrections to the weak rates; order-α quantum-electrodynamic correction to the plasma density, electron mass, and neutrino temperature; and incomplete neutrino decoupling. New results for the finite-temperature radiative correction and the QED plasma correction were used. In addition, we wrote a new and independent nucleosynthesis code designed to control numerical errors to be less than 0.1% . Our predictions for the 4He abundance are presented in the form of an accurate fitting formula. Summarizing our work in one number, YP(η=5×10-10)=0.2462+/-0.0004 (expt) +/-<0.0002 (theory). Further, the baryon density inferred from the Burles-Tytler determination of the primordial D abundance, ΩBh2=0.019+/-0.001, leads to the prediction YP=0.2464+/-0.0005 (D/H) +/-<0.0002 (theory) +/-0.0005 (expt). This ``prediction'' and an accurate measurement of the primeval 4He abundance will allow an important consistency test of primordial nucleosynthesis.

  16. Heat Capacity of Superfluid (sup 4)He in the Presence of a Heat Current Near T

    NASA Technical Reports Server (NTRS)

    Chui, Talso C. P.; Goodstein, David L.; Harter, Alexa W.; Mukhopadhyay, Ranjan

    1996-01-01

    The thermodynamic theory of superfluid helium in the presence of a heat current is presented. We show that there is a thermodynamic relation between the heat capacity and the expression ps(W), which describes the depression of the superfluid density with the counterflow velocity W. Using this relation we show that the heat capacity of superfluid super4He in the presence of a heat current diverges at a depressed lambda transition temperature, suggesting the possibility of a new second order phase transition where the superfluid wave function is not the order parameter.

  17. Measurements of Vortex Line Density Generated by a Quartz Tuning Fork in Superfluid 4He

    NASA Astrophysics Data System (ADS)

    Jackson, M. J.; Kolosov, O.; Schmoranzer, D.; Skrbek, L.; Tsepelin, V.; Woods, A. J.

    2016-05-01

    We present proof-of-concept measurements of the vortex line density generated by a quartz tuning fork resonator probed by the attenuation of second sound in superfluid ^4He at 1.6 K. The force-velocity response of a quartz tuning fork operating at a frequency of 31 kHz exhibited the onset of extra damping at a velocity of 0.5 ms^{-1}. Attenuation of the 5th resonant mode of second sound was observed at the same velocity, indicating the production of vortex lines. Our measurements demonstrate that an increase of the drag coefficient corresponds to the development of quantum turbulence.

  18. Barshay-Temmer test for the 4He( overlined, 3He) 3H reaction

    NASA Astrophysics Data System (ADS)

    Bruno, M.; Cannata, F.; D'agostino, M.; Fiandri, M. L.; Herman, M.; Hofmann, H. M.; Vuaridel, B.; Grüebler, W.; König, V.; Schmelzbach, P. A.; Elsener, K.

    1989-09-01

    The mechanisms of isospin violation in the reaction 4He( overlined, 3He) 3H is studied, in the framework of a microscopic model. To describe realistically the intermediate 6Li nucleus and the fragment states we use the refined resonating group model (RRGM). A detailed analysis of the matrix elements responsible for the asymmetry of cross sections and vector analyzing powers is presented. The isospin violation is found typically of the order of 5-10% and arises mainly from coupling to intermediate "5 + 1" structures in a two-step mechanism. The agreement with the experimental data is fair.

  19. Torsional oscillator and synchrotron x-ray experiments on solid {sup 4}He in aerogel.

    SciTech Connect

    Mulders, N.; West, J. T.; Chan, M. H. W.; Kodituwakku, C. N.; Burns, C. A.; Lurio, L. B.; Univ. of Delaware; Pennsylvania State Univ.; Western Michigan Univ.; Northern Illinois Univ.

    2008-01-01

    X-ray diffraction experiments show that solid {sup 4}He grown in aerogel is highly polycrystalline, with an hcp crystal structure (as in bulk) and a crystallite size of approximately 100 nm. In contrast to the expectation that the highly disordered solid will have a large supersolid fraction, torsional oscillator measurements show a behavior that is strikingly similar to high purity crystals grown from the superfluid phase. The low temperature supersolid fraction is only {approx}3 x 10{sup -4}, and the onset temperature is {approx}100 mK.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  1. 4He Implantation in Natural Diamond: Implications for Apatite (U-Th)/He Thermochronometry

    NASA Astrophysics Data System (ADS)

    Phillips, D.; Kohn, B. P.; Gleadow, A. J.; Harris, J. W.

    2007-12-01

    Current apatite (U-Th)/He thermochronometry protocols correct for ejection of α-particles from grain margins. However, the potential for implantation of 4He into apatite grains, from primary or secondary actinide minerals, has received more limited attention. Evidence for significant natural α-fluxes in the near- surface environment is provided by surface feature and He abundance studies on diamond. Intense α- damage induces a green colour centre in diamond, enabling visual assessment of natural α-implantation doses. Diamonds with transparent green coats and/or green spots occur in most primary and detrital diamond deposits worldwide, indicating that α-implantation rates into upper crustal minerals may be more significant than previously envisaged. Experiments on transparent green-coated natural diamonds reveal implanted αHe concentrations up to 0.015 cc/g, attributed to secondary uranium phases deposited by circulating groundwater (Shelkov et al., 1998). Implantation of similar α-dosages into apatite grains would increase (U-Th)/He ages by up to several hundred percent, dependent on α-dose rate, grain dimensions and actinide content. Investigation of actinide-rich granites in Australia has revealed the common juxtaposition of apatite and actinide phases such as monazite and zircon. In addition, secondary actinide-bearing phases (e.g. uraninite) are observed along joints, fractures, miarolitic cavities and weathering fronts, thus providing additional α-sources. These results demonstrate that (U-Th)/He thermochronometry analyses of apatite, particularly from actinide-rich, weathered granites and sediments, need to evaluate the potential for 4He implantation in the near-surface environment. Insight into the extent of this problem may be achievable through multiple analyses of single grains, in situ laser probe analyses, 4He/3He step-heating experiments, abrasion of grains and/or complementary apatite fission track analyses. Reference: Shelkov, D

  2. Communication: Nucleation of quantized vortex rings in {sup 4}He nanodroplets

    SciTech Connect

    Mateo, David; Leal, Antonio; Barranco, Manuel; Pi, Martí; Hernando, Alberto; Cargnoni, Fausto; Mella, Massimo; Zhang, Xiaohang; Drabbels, Marcel

    2014-04-07

    Whereas most of the phenomena associated with superfluidity have been observed in finite-size helium systems, the nucleation of quantized vortices has proven elusive. Here we show using time-dependent density functional simulations that the solvation of a Ba{sup +} ion created by photoionization of neutral Ba at the surface of a {sup 4}He nanodroplet leads to the nucleation of a quantized ring vortex. The vortex is nucleated on a 10 ps timescale at the equator of a solid-like solvation structure that forms around the Ba{sup +} ion. The process is expected to be quite general and very efficient under standard experimental conditions.

  3. Measurements of Superfluid 4He Flow Through Sub-15 nm Aperture Arrays

    SciTech Connect

    Hoffmann, J. A.; Hunt, B.; Wang, M.; Davis, J. C.; Black, C. T.

    2006-09-07

    We have constructed an experiment designed to study Josephson phenomena in 4He. Motivated by reports and our ideas for novel silicon nanofabrication techniques, we designed the experiment to study the possibility of a transition from stochastic to coherent phase slippage. Here we briefly describe the nanofabrication of sub-15 nm aperture arrays and show preliminary data. For temperatures below 2 K, these data show temperature dependence of the superfluid critical velocity through the weak link which is characteristic of phase-slip limited flow.

  4. Spatially Extended Avalanches in a Hysteretic Capillary Condensation System: Superfluid {sup {bold 4}}He in Nuclepore

    SciTech Connect

    Lilly, M.P.; Wootters, A.H.; Hallock, R.B.

    1996-11-01

    Capacitive studies of hysteretic capillary condensation of superfluid {sup 4}He in Nuclepore have shown that the initial draining of the pores occurs over a small range of the chemical potential with avalanches present as groups of pores drain. In the work reported here, the avalanches in this system are shown to be nonlocal events which involve pores distributed at low density across the entire sample. The nonlocal avalanche behavior is shown to be enabled by the presence of a superfluid film connection among the pores. {copyright} {ital 1996 The American Physical Society.}

  5. Formation of a Mesa Shaped Phonon Pulse in Superfluid 4He

    NASA Astrophysics Data System (ADS)

    Adamenko, I. N.; Nemchenko, K. E.; Slipko, V. A.

    2010-05-01

    We present a theory for the formation of a mesa shaped phonon pulse in superfluid 4He. Starting from the hydrodynamic equations of superfluid helium, we obtain the system of equations which describe the evolution of strongly anisotropic phonon systems. Such systems can be created experimentally. The solution of the equations are simple waves, which correspond to second sound in the moving phonon pulse. Using these exact solutions, we describe the expansion of phonon pulses in superfluid helium at zero temperature. This theory gives an explanation for the mesa shape observed in the measured phonon angular distributions. Almost all dependencies of the mesa shape on the system parameters can be qualitatively understood.

  6. Velocity distributions of tracer particles in thermal counterflow in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Mineda, Yoshikazu; Tsubota, Makoto; Sergeev, Yuri A.; Barenghi, Carlo F.; Vinen, W. F.

    2013-05-01

    Quantum turbulence accompanying thermal counterflow in superfluid 4He was recently visualized by the Maryland group, using micrometer-sized tracer particles of solid hydrogen [Paoletti, Fiorito, Sreenivasan, and Lathrop, J. Phys. Soc. Jpn.10.1143/JPSJ.77.111007 77, 111007 (2008)]. In order to understand the observations, we formulate the coupled dynamics of fine particles and quantized vortices, in the presence of a relative motion of the normal and superfluid components. Numerical simulations based on this formulation are shown to agree reasonably well with experimental observations of the velocity distributions of the tracer particles in thermal counterflow.

  7. Simultaneous measurements of the torsional oscillator anomaly and thermal conductivity in solid 4He.

    PubMed

    Zmeev, D E; Golov, A I

    2011-08-01

    In these torsional oscillator experiments, the samples of solid (4)He were characterized by measuring their thermal conductivity. Polycrystalline samples of helium of either high isotopic purity or natural concentration of (3)He were grown in an annular container by the blocked-capillary method and investigated before and after annealing. No correlation has been found between the magnitude of the low-temperature shift of the torsional oscillator frequency and the amount of crystalline defects as measured by the thermal conductivity. In samples with the natural (3)He concentration, a substantial excess thermal conductivity over the usual T(3) dependence was observed below 120 mK.

  8. Dynamics of the BCC-HCP transition of solid 4He

    NASA Astrophysics Data System (ADS)

    Fujii, Hirosuke; Okumura, Yuji; Matsumoto, Koichi; Okuda, Yuichi

    2000-07-01

    We are optically studying the phase transition from BCC to HCP of solid 4He (1.43 K) at melting pressure to investigate how the crystal changes its structure when it is in equilibrium with superfluid. When the temperature was changed slowly through the transition, new phase seeds were nucleated somewhere and those seeds grew in the superfluid phase. The interesting point is that growth of the new seeds is more favorable than the direct solid-solid Martensitic transition. Whereas at the transition of 1.78 K where the solid is in equilibrium with the normal fluid, the transition occurred as an ordinary Martensitic transition.

  9. Crossover from hydrodynamic to acoustic drag on quartz tuning forks in normal and superfluid 4He

    NASA Astrophysics Data System (ADS)

    Bradley, D. I.; Človečko, M.; Fisher, S. N.; Garg, D.; Guise, E.; Haley, R. P.; Kolosov, O.; Pickett, G. R.; Tsepelin, V.; Schmoranzer, D.; Skrbek, L.

    2012-01-01

    We present measurements of the drag forces on quartz tuning forks oscillating at low velocities in normal and superfluid 4He. We have investigated the dissipative drag over a wide range of frequencies, from 6.5 to 600 kHz, by using arrays of forks with varying prong lengths and by exciting the forks in their fundamental and first overtone modes. At low frequencies the behavior is dominated by laminar hydrodynamic drag, governed by the fluid viscosity. At higher frequencies acoustic drag is dominant and is described well by a three-dimensional model of sound emission.

  10. Torsional oscillator experiment on superfluid 4He confined in a porous alumina nanopore array

    NASA Astrophysics Data System (ADS)

    Murakawa, S.; Higashino, R.; Yoshimura, K.; Chikazawa, Y.; Tanaka, T.; Kuriyama, K.; Honda, K.; Shibayama, Y.; Shirahama, K.

    2012-12-01

    We studied superfluidity of liquid 4He confined in an array of well-characterized straight nanopores of porous alumina (PA). The PA plate sample of 45 nm pore size is set in an annular flow channel and the superflow is detected by torsional oscillator (TO) technique. Superfluid transition Tc in the nanopores is suppressed by 3.5 mK from the bulk λ point. Tc is consistent with the temperature at which the healing length is equal to the pore radius. We have observed many anti-crossing anomalies in the TO frequency associated with dissipation peaks, which are attributed to the coupling to second sound resonances.

  11. Spin-polarized hydrogen adsorbed on the surface of superfluid {sup 4}He

    SciTech Connect

    Marín, J. M.; Boronat, J.; Markić, L. Vranješ

    2013-12-14

    The experimental realization of a thin layer of spin-polarized hydrogen H↓ adsorbed on top of the surface of superfluid {sup 4}He provides one of the best examples of a stable, nearly two-dimensional (2D) quantum Bose gas. We report a theoretical study of this system using quantum Monte Carlo methods in the limit of zero temperature. Using the full Hamiltonian of the system, composed of a superfluid {sup 4}He slab and the adsorbed H↓ layer, we calculate the main properties of its ground state using accurate models for the pair interatomic potentials. Comparing the results for the layer with the ones obtained for a strictly 2D setup, we analyze the departure from the 2D character when the density increases. Only when the coverage is rather small the use of a purely 2D model is justified. The condensate fraction of the layer is significantly larger than in 2D at the same surface density, being as large as 60% at the largest coverage studied.

  12. Bose condensate in superfluid sup 4 He and momentum distributions by deep inelastic scattering

    SciTech Connect

    Silver, R.N. ); Sokol, P.E. . Dept. of Physics)

    1989-01-01

    There are several reasons for the high interest in the recent experimental and theoretical progress in understanding deep inelastic neutron scattering from liquid {sup 4}He: it tests the fundamental London hypothesis of a connection between superfluidity and Bose condensation; it provides a quantitative test of ab-initio calculational methods for all systems with strong correlations which are the focus of current quantum many-body research; and it establishes the range of validity of deep inelastic scattering as a method for measuring momentum distributions. In this paper we introduce the concepts of impulse approximation in more detail, we describe recent progress in the theory for final state corrections to the impulse approximation, we present quantitative predictions for neutron scattering experiments, we compare with recent high energy pulsed neutron source experiments on liquid {sup 4}He by P. Sokol and colleagues as well as other attempts to extract the Bose condensate fraction from the neutron scattering data, and we discuss the implications of this progress for future momentum distribution experiments in other systems such as liquid {sup 3}He and quasi-elastic electron nucleus scattering. 42 refs., 23 figs.

  13. Depression of the Superfluid Transition Temperature in 4He by a Heat Flow

    NASA Astrophysics Data System (ADS)

    Yin, Liang; Lin, Peng; Qi, Xin

    2014-11-01

    The depression of the superfluid transition temperature Tλ in 4He by a heat flow Q is studied. A small sealed cell with a capillary is introduced and a stable and flat superfluid transition temperature plateau is easily obtained by controlling the temperature of the variable-temperature platform and the bottom chamber of the sealed cell. Owing to the depression effect of the superfluid transition temperature by the heat flow, the heat flow through the capillary is changed by the temperature control to obtain multiple temperature plateaus of different heat flows. The thermometer self-heating effect, the residual heat leak of the 4.2 K environment, the temperature difference on the He II liquid column, the Kapiza thermal resistance between the liquid helium and the copper surface of the sealed cell, the temperature gradient of the sealed cell, the static pressure of the He II liquid column and other factors have influence on the depression effect and the influence is analyzed in detail. Twenty experiments of the depression of the superfluid transition temperature in 4He by heat flow are made with four sealed cells in one year. The formula of the superfluid transition temperature pressured by the heat flow is Tλ (Q) = -0.00000103Q + 2.1769108, and covers the range 229 <= Q <= 6462 μW/cm2.

  14. Giant isochoric compressibility of solid 4He: The bistability of superclimbing dislocations

    NASA Astrophysics Data System (ADS)

    Kuklov, A. B.

    2015-10-01

    A significant accumulation of matter in solid 4He observed during a superflow event, dubbed the giant isochoric compressibility (or the syringe effect), is discussed within the model of dislocations with superfluid core. It is shown that solid 4He in contact with a superfluid reservoir can develop a bistability with respect to the syringe fraction, with the threshold for the bias by chemical potential determined by a typical free length of dislocations with superfluid core. The main implications of this effect are hysteresis and strongly nonlinear dynamical behavior leading to growth, proliferation, and possibly exiting from a crystal of superclimbing dislocations. Three major channels for such dynamics are identified: (i) injection and inflation of the prismatic loops from the boundary, (ii) Bardeen-Herring generation of the loops in the bulk, and (iii) helical instability of the screw dislocations. It is argued that the syringe instability may have already been observed in the experiments on the superflow through solid Helium-4. Several testable predictions for the time and the bias dependencies of the dynamics are suggested.

  15. Ab initio many-body calculations of nucleon-4He scattering with three-nucleon forces

    DOE PAGESBeta

    Hupin, Guillaume; Langhammer, Joachim; Navratil, Petr; Quaglioni, Sofia; Calci, Angelo; Roth, Robert

    2013-11-27

    We extend the ab initio no-core shell model/resonating-group method to include three-nucleon (3N) interactions for the description of nucleon-nucleus collisions. We outline the formalism, give algebraic expressions for the 3N-force integration kernels, and discuss computational aspects of two alternative implementations. The extended theoretical framework is then applied to nucleon-4He elastic scattering using similarity-renormalization-group (SRG)-evolved nucleon-nucleon plus 3N potentials derived from chiral effective field theory. We analyze the convergence properties of the calculated phase shifts and explore their dependence upon the SRG evolution parameter. We include up to six excited states of the 4He target and find significant effects from themore » inclusion of the chiral 3N force, e.g., it enhances the spin-orbit splitting between the 3/2– and 1/2– resonances and leads to an improved agreement with the phase shifts obtained from an accurate R-matrix analysis of the five-nucleon experimental data. As a result, we find remarkably good agreement with measured differential cross sections at various energies below the d+3H threshold, while analyzing powers manifest larger deviations from experiment for certain energies and angles.« less

  16. Excitations in a thin liquid {sup 4}He film from inelastic neutron scattering

    SciTech Connect

    Clements, B.E. |; Godfrin, H.; Krotscheck, E. |; Lauter, H.J.; Leiderer, P.; Passiouk, V. |; Tymczak, C.J.

    1996-05-01

    We perform a thorough analysis of the experimental dynamic structure function measured by inelastic neutron scattering for a low-temperature ({ital T}=0.65 K) four-layer liquid {sup 4}He film. The results are interpreted in light of recent theoretical calculations of the (nonvortex) excitations in thin liquid Bose films. The experimental system consists of four outer liquid layers, adsorbed to two solid inner {sup 4}He layers, which are themselves adsorbed to a graphite substrate. Relatively intense surface (ripplon) and bulklike modes are observed. The analysis of the experimental data gives strong evidence for still other modes and supports the long-standing theoretical predictions of layerlike modes (layer phonons) associated with excitations propagating primarily within the liquid layers comprising the film. The results of the analysis are consistent with the occurrence of level crossings between modes, and the existence of a layer modes for which the theory predicts will propagate in the vicinity of the solid-liquid interface. The theory and experiment agree on the detailed nature of the ripplon; its dispersion at low momenta, its fall off in intensity at intermediate momenta, and the level crossings at high momentum. Similar to experiment, the theory yields an intense mode in the maxon-roton region which is intrepreted as the formation of the bulklike excitation. {copyright} {ital 1996 The American Physical Society.}

  17. Missing Lead and High 3He/4He in Ancient Sulfides Associated with Continental Crust Formation

    PubMed Central

    Huang, Shichun; Lee, Cin-Ty A.; Yin, Qing-Zhu

    2014-01-01

    Major terrestrial reservoirs have Pb isotopes more radiogenic than the bulk silicate Earth. This requires a missing unradiogenic Pb reservoir, which has been argued to reside in the lower continental crust or dissolved in the core. Chalcophile element studies indicate that continent formation requires the formation of sulfide-bearing mafic cumulates in arcs. Because Pb, but not U, partitions into sulfides, we show that continent formation must have simultaneously generated time-integrated unradiogenic Pb reservoirs composed of sulfide-bearing cumulates, now recycled back into the mantle or stored deep in the continental lithosphere. The generation of such cumulates could also lead to coupled He-Pb isotopic systematics because 4He is also produced during U-Th-Pb decay. Here, we show that He may be soluble in sulfide melts, such that sulfide-bearing cumulates would be enriched in both Pb and He relative to U and Th, “freezing” in He and Pb isotopes of the ambient mantle at the time of sulfide formation. This implies that ancient sulfide-bearing cumulates would be characterized by unradiogenic Pb and He isotopes (high-3He/4He). These primitive signatures are usually attributed to primordial, undifferentiated mantle, but in this case, they are the very imprint of mantle differentiation via continent formation. PMID:24937103

  18. Experiments on the rapid mechanical expansion of liquid 4He through its superfluid transition.

    PubMed

    Efimov, V B; Griffiths, O J; Hendry, P C; Kolmakov, G V; McClintock, P V E; Skrbek, L

    2006-11-01

    Phenomena following a rapid mechanical quench of liquid 4He from its normal to its superfluid phase are reported and discussed. The mechanical expansion apparatus is an improved version of that described previously. It uses a double-cell geometry to effect a partial separation of the sample from the convolutions of the bellows that form the outer wall of the cell. Consistent with earlier work, no evidence is found for the production of quantized vortices via the Kibble-Zurek (KZ) mechanism. Although the expansion is complete within 15ms , the second-sound velocity and attenuation continue to increase for a further approximately 60ms ; correspondingly the temperature decreases. Subsequently, the temperature rises again toward its final value as the second-sound velocity and attenuation decrease. It is shown that this unexpected behavior is apparently associated with a large-amplitude second-sound oscillation produced by the expansion, and it is suggested that the observed vortices are created by the normal fluid-superfluid counterflow that constitutes the second-sound wave. If production of large-amplitude second sound is inherent to the mechanical expansion of liquid 4He through the superfluid transition, as appears to be the case for final temperatures more than 3mK from the lambda transition, the phenomenon sets a lower bound on the density of KZ vortices that can be detected in this type of experiment. PMID:17279991

  19. Is there a stable commensurate solid phase in the second 4He layer on graphite? - path integral Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Ahn, Jeonghwan; Lee, Hoonkyung; Kwon, Yongkyung

    2015-03-01

    Existence of a stable commensurate structure in the second 4He layer on graphite has been a subject of intensive experimental and theoretical studies because of its implication in the possible realization of two-dimensional supersolidity. Earlier path-integral Monte Carlo (PIMC) calculations of Pierce and Manousakis predicted a stable C4/7 commensurate structure above the first-layer 4He atoms fixed at triangular lattice sites, but Corboz et al. later showed that no commensurate phase was stable when quantum dynamics of the first-layer 4He atoms was incorporated in the PIMC calculations. On the other hand, recent heat capacity measurements of Nakamura et al. provided a strong evidence for a commensurate solid in the second 4He layer over an extended density range. Motivated by this, we have performed new PIMC calculations for the second helium layer on graphite. Unlike previous PIMC calculations where a laterally-averaged one-dimensional substrate potential was used, we here employ an anisotropic 4He-graphite potential described by a sum of the 4He-C pair potentials. With this fully-corrugated substrate potential we make more accurate description of quantum dynamics of the first-layer 4He atoms and analyze its effects on the phase diagram of the second layer.

  20. Radial sensitivity of the optical model potentials for 4He+120Sn and 6He+120Sn

    NASA Astrophysics Data System (ADS)

    Sert, Y.; Boztosun, I.

    2016-09-01

    In this paper, the radial sensitivity of the elastic scattering cross-section for the 4He and 6He on 120Sn have been examined at energies near the Coulomb barrier. We also investigate the variation of the potential radius depending on the incident energy for the 4He +120Sn and 6He +120Sn systems. Especially, we have taken care of to stay within one family for 4He +120Sn elastic scattering, i.e., using V0 real depth have not been changed by more than 20-30%.

  1. Communication: Unraveling the {sup 4}He droplet-mediated soft-landing from ab initio-assisted and time-resolved density functional simulations: Au@{sup 4}He{sub 300}/TiO{sub 2}(110)

    SciTech Connect

    Lara-Castells, María Pilar de Aguirre, Néstor F.; Stoll, Hermann; Mitrushchenkov, Alexander O.; Mateo, David; Pi, Martí

    2015-04-07

    An ab-initio-based methodological scheme for He-surface interactions and zero-temperature time-dependent density functional theory for superfluid {sup 4}He droplets motion are combined to follow the short-time collision dynamics of the Au@{sup 4}He{sub 300} system with the TiO{sub 2}(110) surface. This composite approach demonstrates the {sup 4}He droplet-assisted sticking of the metal species to the surface at low landing energy (below 0.15 eV/atom), thus providing the first theoretical evidence of the experimentally observed {sup 4}He droplet-mediated soft-landing deposition of metal nanoparticles on solid surfaces [Mozhayskiy et al., J. Chem. Phys. 127, 094701 (2007) and Loginov et al., J. Phys. Chem. A 115, 7199 (2011)].

  2. Heat capacity of {sup 4}He in Vycor near the critical coverage

    SciTech Connect

    Van Keuls, F.W.; Crowell, P.A.; Reppy, J.D.

    1993-04-01

    The authors report heat capacity measurements of {sup 4}He films in Vycor near the critical coverage. The goal of these studies is to determine whether the low temperature phase at coverages below the onset of superfluidity is a glass or an insulator with a gap. The data cover a temperature range of 5 mK to 600 mK. At the lowest temperatures, a CMN DC-SQUID thermometer is used. This thermometer contains 3 mg of CMN to minimize its heat capacity. The sensitivity at 10 mK is better than 500 pK/{radical}Hz. The CMN powder is mixed with a Ag sinter to improve thermal conductivity. The resistance thermometers mounted on the cell are found to be reliable down to 14 mK.

  3. 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

    2005-12-01

    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.

  4. The 4He(e,e'p)3H Reaction at Jlab

    SciTech Connect

    Bodo Reitz

    2003-05-01

    In the recent experiment E97-111 at Jefferson Lab the unseparated cross section for the (e,e{prime}p) reaction on {sup 4}He was measured at recoil momenta up to 530 MeV/c. In the plane-wave impulse approximation, many calculations predict a sharp minimum in the cross section for recoil momenta around 450 MeV/c and show that its location is sensitive to the short-range part of the internucleon potential. However, reaction dynamic effects such as final-state interactions and meson-exchange currents can obscure such a minimum. To distinguish and study these effects data were taken at several different kinematic points. The preliminary results of the experiment are presented and compared to recent model calculations.

  5. Studies of the 4He Nucleus in the (e,e'p) Reaction

    SciTech Connect

    Bodo Reitz

    2003-10-01

    Jefferson Lab experiment E97-111 measured the unseparated cross section for the (e,e'p) reaction on {sup 4}He at recoil momenta up to 530 {approx} MeV/c. In the plane-wave impulse approximation, many calculations predict a sharp minimum in the cross section for recoil momenta around 450 {approx} MeV/c and show that its location is sensitive to the short-range part of the internucleon potential. However, reaction dynamic effects such as final-state interactions and meson-exchange currents can obscure such a minimum. To distinguish and study these effects data were taken at several different kinematics. The preliminary results of the experiment are presented and compared to recent model calculations.

  6. Dynamic structure factor of liquid 4He across the normal-superfluid transition

    NASA Astrophysics Data System (ADS)

    Ferré, G.; Boronat, J.

    2016-03-01

    We have carried out a microscopic study of the dynamic structure factor of liquid 4He across the normal-superfluid transition temperature using the path integral Monte Carlo method. The ill-posed problem of the inverse Laplace transform, from the imaginary-time intermediate scattering function to the dynamic response, is tackled by stochastic optimization. Our results show a quasiparticle peak and a small and broad multiphonon contribution. In spite of the lack of strength in the collective peaks, we clearly identify the rapid dropping of the roton peak amplitude when crossing the transition temperature Tλ. Other properties such as the static structure factor, static response, and one-phonon contribution to the response are also calculated at different temperatures. The changes of the phonon-roton spectrum with the temperature are also studied. An overall agreement with available experimental data is achieved.

  7. Disappearance of Roton Propagation in Superfluid {sup 4}He at T{sub {lambda}}

    SciTech Connect

    Svensson, E.C.; Montfrooij, W.; de Schepper, I.M.

    1996-11-01

    Using neutron scattering, we determine the dynamic structure factor {ital S}({ital q},{nu}) of liquid {sup 4}He for the roton wave number {ital q}=2.0{sup {minus}1} as a function of frequency {nu} at constant density 0.1715 gcm{sup {minus}3} and for ten temperatures in the range 1.08{le}{ital T}{le}2.00 K, primarily near the superfluid transition temperature {ital T}{sub {lambda}}=1.9202 K. The {lambda} transition is marked by a complete softening of the roton mode and a rapid decrease in lifetime. This change is continuous with temperature, and we find no evidence for a new mode appearing as one enters the superfluid phase, as has been proposed on the basis of theoretical considerations. {copyright} {ital 1996 The American Physical Society.}

  8. Critical Scaling Properties at the Superfluid Transition of {sup 4}He in Aerogel

    SciTech Connect

    Nikolaou, Marios; Wallin, Mats; Weber, Hans

    2006-12-01

    We study the superfluid transition of {sup 4}He in aerogel by Monte Carlo simulations and finite size scaling analysis. Aerogel is a highly porous silica glass, which we model by a diffusion limited cluster aggregation model. The superfluid is modeled by a three dimensional XY model, with excluded bonds to sites on the aerogel cluster. We obtain the correlation length exponent {nu}=0.73{+-}0.02, in reasonable agreement with experiments and with previous simulations. For the heat capacity exponent {alpha}, both experiments and previous simulations suggest deviations from the Josephson hyperscaling relation {alpha}=2-d{nu}. In contrast, our Monte Carlo results support hyperscaling with {alpha}=-0.2{+-}0.05. We suggest a reinterpretation of the experiments, which avoids scaling violations and is consistent with our simulation results.

  9. {sup 3}He+{sup 4}He {yields} {sup 7}Be astrophysical S factor

    SciTech Connect

    Brown, T. A. D.; Bordeanu, C.; Snover, K. A.; Storm, D. W.; Melconian, D.; Sallaska, A. L.; Sjue, S. K. L.; Triambak, S.

    2007-11-15

    We present precision measurements of the {sup 3}He+{sup 4}He {yields} {sup 7}Be reaction in the range E{sub c.m.}=0.33 to 1.23 MeV using a small gas cell and detection of both prompt {gamma} rays and {sup 7}Be activity. Our prompt and activity measurements are in good agreement within the experimental uncertainty of several percent. We find S(0)=0.595{+-}0.018 keV b from fits of the Kajino theory to our data. We compare our results with published measurements, and we discuss the consequences for Big Bang Nucleosynthesis and for solar neutrino flux calculations.

  10. Experimental study of nanofluidics and phase transitions of normal and superfluid 4He

    NASA Astrophysics Data System (ADS)

    Velasco, Angel Enriques

    This thesis addresses the experimental results of two different research topics. The first is the experimental work of pressure driven flows in the smallest, single nanotubes ever investigated. The nanotube boundary conditions and slip lengths from argon, nitrogen, water, and helium experiments were analyzed and compared to macroscopic boundary conditions. The second research topic discusses the work on ellipsometric and quartz microbalance measurements of the 2D superfluid phase diagram of 4He on alkali substrates. Ellipsometric results of sodium on HOPG provide the first evidence of the existence of the 2D critical point on an intermediate strength substrate. Pressure driven flows through single nanopores and microtubes were measured with a calibrated mass spectrometer with pressure drops up to 30 Atm. The nanopores were between 30 nm to 600 nm in diameter and etched in mica and PET membranes of several microns thickness. Microtubes several inches long of fused quartz and nickel material were tested with diameters between 1.8 micron and 25 micron. For 4He and argon gas we observed the flow transition between the free molecular and continuum regimes at 293 K and 77 K. No discrepancy between the macroscopic theory and the 30 nm nanopore data was found. Because of the exceptionally low viscosity of gaseous helium the laminar-turbulent transition could also be observed within these submicron channels. The small viscosity of 4He was too small to dampen inertial effects at a Reynolds number of 2000. In addition to single phase gas flows, our experimental technique also allows us to investigate flows in which the nano or micro scale pipe is either partially or completely filled with liquids. The position of the intrinsic liquid/vapor interface was important for understanding this type of flow. Strong evaporation and cooling at the liquid-vapor interface can lead to freezing for conventional fluids such as nitrogen and water, which in turn leads to complex intermittent

  11. A predictive theory for elastic scattering and recoil of protons from 4He

    DOE PAGESBeta

    Hupin, Guillaume; Quaglioni, Sofia; Navratil, Petr

    2014-12-08

    Low-energy cross sections for elastic scattering and recoil of protons from 4He nuclei (also known as α particles) are calculated directly by solving the Schrodinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe the concentrations and depth profiles ofmore » either hydrogen or helium. Furthermore, we compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among data sets and can be used to predict these cross sections when measurements are not available.« less

  12. Ac vortex-dependent torsional oscillation response and onset temperature T0 in solid 4He.

    PubMed

    Penzev, Andrey; Yasuta, Yoshinori; Kubota, Minoru

    2008-08-01

    Detailed studies of ac velocity V_{ac} and T dependence of torsional oscillator responses of solid 4He are reported. A characteristic onset temperature T_{0} approximately 0.5 K is found, below which a significant V_{ac}-dependent change occurs in the energy dissipation for the samples at approximately 32 bar and for one at 49 bar. A V_{ac} dependence of the so-called "nonclassical rotational inertia" fraction also appears below approximately T_{0}. The log(V_{ac}) linear dependence, which suggests involvement of quantized vorticies, was examined in the nonclassical rotational inertia fraction. We find a common 1/T;{2} dependence for this linear slope change in all of the samples for 30

  13. 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.

  14. Nuclear Transparency with the gamma + n -> pi- + p Process in 4He

    SciTech Connect

    Dipangkar Dutta; Feng Xiong; Lingyan Zhu; John Arrington; Todd Averett; Elizabeth Beise; John Calarco; Ting Chang; Jian-Ping Chen; Eugene Chudakov; Marius Coman; Benjamin Clasie; Christopher Crawford; Sonja Dieterich; Frank Dohrmann; Kevin Fissum; Salvatore Frullani; Haiyan Gao; Ronald Gilman; Charles Glashausser; Javier Gomez; Kawtar Hafidi; Jens-Ole Hansen; Douglas Higinbotham; R.J. Holt; Cornelis De Jager; Xiaochao Zheng; X. Jiang; Edward Kinney; Kevin Kramer; Gerfried Kumbartzki; John LeRose; Nilanga Liyanage; David Mack; Pete Markowitz; Kathy McCormick; Zein-Eddine Meziani; Robert Michaels; J. Mitchell; Sirish Nanda; David Potterveld; Ronald Ransome; Paul Reimer; Bodo Reitz; Arunava Saha; Elaine Schulte; Charles Seely; Simon Sirca; Steffen Strauch; Vincent Sulkosky; Branislav Vlahovic; Lawrence Weinstein; Krishni Wijesooriya; Claude Williamson; Bogdan Wojtsekhowski; Hong XIANG; Wang Xu; J. Zeng

    2003-08-01

    We have measured the nuclear transparency of the fundamental process {gamma} n {yields} {pi}{sup -} p in {sup 4}He. These measurements were performed at Jefferson Lab in the photon energy range of 1.6 to 4.5 GeV and at {theta}{sub cm}{sup {pi}} = 70{sup o} and 90{sup o}. These measurements are the first of their kind in the study of nuclear transparency in photoreactions. They also provide a benchmark test of Glauber calculations based on traditional models of nuclear physics. The transparency results suggest deviations from the traditional nuclear physics picture. The momentum transfer dependence of the measured nuclear transparency is consistent with Glauber calculations which include the quantum chromodynamics phenomenon of color transparency.

  15. Polarization Transfer in 4He(e-vector,e[prime]p-vector)3H

    SciTech Connect

    Michael Paolone

    2007-10-01

    Polarization transfer in quasi-elastic nucleon knockout is sensitive to the properties of the nucleon in the nuclear medium, including possible modification of the nucleon form factor and/or spinor. In our recently completed experiment E03-104 at Jefferson Lab we measured the proton recoil polarization in the 4He(e-vector,e[prime]p-vector)3H reaction at a Q2 of 0.8 (GeV/c)2 and 1.3 (GeV/c)2 with unprecedented precision. These data complement earlier data between 0.4 and 2.6 (GeV/c)2 from both Mainz and Jefferson Lab, in which the measured ratio of polarization-transfer coefficients differs from a fully relativistic DWIA calculation. Preliminary results hint at a possible unexpected Q2 dependence in the polarization transfer coefficient ratio. Final analysis will help constrain FSI models

  16. 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.

  17. Response functions of imaging plates to photons, electrons and {sup 4}He particles

    SciTech Connect

    Bonnet, T.; Denis-Petit, D.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Aléonard, M. M.

    2013-10-15

    Imaging plates from Fuji (BAS-SR, MS, and TR types) are phosphor films routinely used in ultra high intensity laser experiments. However, few data are available on the absolute IP response functions to ionizing particles. We have previously measured and modeled the IP response functions to protons. We focus here on the determination of the responses to photons, electrons, and {sup 4}He particles. The response functions are obtained on an energy range going from a few tens of keV to a few tens of MeV and are compared to available data. The IP sensitivities to the different ionizing particles demonstrate a quenching effect depending on the particle stopping power.

  18. Microscopic optical model calculations of 4He, 12C-nucleus absorption cross sections

    NASA Technical Reports Server (NTRS)

    Dubey, R. R.; Khandelwal, G. S.; Cucinotta, F. A.; Wilson, J. W.

    1996-01-01

    Calculations of absorption cross sections using a microscopic first-order optical potential for heavy-ion scattering are compared with experiments. In-medium nucleon-nucleon (NN) cross sections were used to calculate the two-body scattering amplitude. A medium-modified first-order optical potential was obtained for heavy-ion scattering using the in-medium two-body scattering amplitude. A partial wave expansion of the Lippmann-Schwinger equation in momentum space was used to calculate the absorption cross sections for various systems. The results are presented for the absorption cross sections for 4He-nucleus and 12C-nucleus scattering systems and are compared with the experimental values in the energy range 18-83A MeV. The use of the in-medium NN cross sections is found to result in significant reduction of the free space absorption cross sections in agreement with experiment.

  19. Russell Donnelly's last legacy: Pursuing grid turbulence in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Ihas, Gary; Yang, Jihee

    2015-11-01

    Quantum turbulence, a tangle of quantized vortex lines in a superfluid, may hold significant keys to understanding all types of turbulence. Russell Donnelly pioneered this line of research, beginning with studies of grid turbulence probed by second sound. The apparatus built by Russell and his students, with significant up-grades, is now being used at the University of Florida to continue his work on decaying grid turbulence in superfluid 4He. The Oregon work used a 1cm wide square channel, while the Florida work has been in both 1 cm and 5 cm square channels. The larger channel allows detailed study of the increase in eddy size before saturation at the channel walls during the decay process. Power law fits of the turbulence decay in time allow comparison with theory, work intended to be Russell Donnelly's last experiment. Supported in part by US NSF #1007937.

  20. Theoretical analysis of the anomalous spectral splitting of tetracene in 4He droplets.

    PubMed

    Whitley, Heather D; DuBois, Jonathan L; Whaley, K Birgitta

    2011-06-30

    We present a theoretical analysis of the electronic absorption spectra of tetracene in (4)He droplets based on many-body quantum simulations. Using the path integral ground state approach, we calculate one- and two-body reduced density matrices of the most strongly localized He atoms near the molecule surface and use these to investigate the helium ground-state quantum coherence and correlations when tetracene is in its electronic ground and excited states. We identify a trio of quasi-one-dimensional, strongly localized atoms adsorbed along the long axis of the molecule that show some quantum coherence among themselves but far less with the remaining solvating helium. We evaluate the single-particle natural orbitals of the localized He atoms by diagonalization of the one-body density matrix and use these to construct single- and many-particle solvating helium basis states with which the zero-phonon spectral features of the tetracene-(4)He(N) absorption spectrum are then calculated. The absorption spectrum resulting from the three-body density matrix for the strongly bound trio of helium atoms is in very good agreement with the experimental data, accounting quantitatively for the anomalous splitting of the zero-phonon line [Hartmann, M.; Lindinger, A.; Toennies, J. P.; Vilesov, A. F. Chem. Phys. 1998, 239, 139; Krasnokutski, S.; Rouillé, G.; Huisken, F. Chem. Phys. Lett. 2005, 406, 386]. Our results indicate that the combination of strong localization and the quasi-one-dimensional nature of trios of helium atoms adsorbed along the long axis of tetracene leads to a quantum coherent, yet highly correlated ground state for the helium density closest to the molecule. The spectroscopic analysis shows that this feature accounts quantitatively for the anomalous splittings and hitherto unexplained fine structure observed in the absorption spectra of tetracene and suggests that it may be responsible for the corresponding zero-phonon splittings in other quasi

  1. Distinguishing 3He and 4He with the Electron Proton Telescope (EPT) on Solar Orbiter

    NASA Astrophysics Data System (ADS)

    Boden, S.; Kulkarni, S. R.; Steinhagen, J.; Tammen, J.; Martin-Garcia, C.; Wimmer-Schweingruber, R. F.; Boettcher, S. I.; Seimetz, L.; Ravanbakhsh, A.; Elftmann, R.; Schuster, B.; Kulemzin, A.; Kolbe, S.; Mahesh, Y.; Knieriem, V.; Yu, J.; Kohler, J.; Panitzsch, L.; Terasa, C.; Boehm, E.; Rodriguez-Pacheco, J.; Prieto, M.; Gomez-Herrero, R.

    2015-12-01

    The Electron Proton Telescope (EPT) is one of the sensors of the Energetic Particle Detector (EPD) for the Solar Orbiter mission, which will provide key measurements to address particle acceleration at and near the Sun. The EPD suite consists of four different sensors (STEP, SIS, EPT and HET) which together will resolve the energetic particle spectrum from 2 keV to 20 MeV for electrons, 3 keV to 100 MeV for protons and circa 100 keV/nuc to 100 MeV/nuc for heavier ions.EPT itself is primarily designed to cleanly separate and measure electrons in the energy range from 20 - 400 keV and protons from 20 - 7000 keV. To achieve this, EPT uses two back-to-back solid state detectors with a magnet system to deflect electrons on one side and a Polyimide foil to stop protons below ~400 keV on the other side. The two detectors then serve as each other's anti-coincidence. Additionally this setup also allows us to measure penetrating particles with deposited energies in the 1 MeV to 40 MeV range. Looking at the ratio of deposited energy in the two detectors versus total deposited energy allows us to differentiate between protons and alpha particles. Distinguishing 3He from 4He will be challenging, but possible provided good knowledge of the instrument, high-fidelity modeling and a precise calibration of EPT. Here, we will present feasibility studies leading to a determination of the 3He / 4He ratio with EPT.

  2. Phonon-roton modes of liquid 4He beyond the roton in MCM-41

    SciTech Connect

    Azuah, Richard T; Omar Diallo, Souleymane; Adams, Mark A.; Kirichek, Oleg; Glyde, Henry R

    2013-01-01

    We present neutron scattering measurements of the phonon-roton (P-R) mode of superfluid 4He confined in 47 A MCM-41 at T = 0.5 K at wave vectors, Q, beyond the roton wave vector (QR = 1.92 A-1). Measurements beyond the roton require access to high wave vectors (up to Q = 4 A-1) with excellent energy resolution and high statistical precision. The present results show for the first time that at T = 0.5 K the P-R mode in MCM-41 extends out to wave-vector Q 3.6 A-1 with the same energy and zero width (within precision) as observed in bulk superfluid 4He. Layer modes in the roton region are also observed. Specifically, the P-R mode energy, !Q, increases with Q for Q > QR and reaches a plateau at a maximum energy !Q = 2 where is the roton energy, = 0.74 0.01 meV in MCM-41. This upper limit means the P-R mode decays to two rotons when its energy exceeds 2 . It also means that the P-R mode does not decay to two layers modes. If the P-R could decay to two layer modes, !Q would plateau at a lower energy, !Q = 2 L where L = 0.60 meV is the energy of the roton like minimum of the layer mode. The observation of the P-R mode with energy up to 2 shows that the P-R mode and the layer modes are independent modes with apparently little interaction between them.

  3. Probing Liquid ^4He with Quartz Tuning Forks Using a Novel Multifrequency Lock-in Technique

    NASA Astrophysics Data System (ADS)

    Bradley, D. I.; Haley, R. P.; Kafanov, S.; Noble, M. T.; Pickett, G. R.; Tsepelin, V.; Vonka, J.; Wilcox, T.

    2016-09-01

    We report on a novel technique to measure quartz tuning forks, and possibly other vibrating objects, in a quantum fluid using a multifrequency lock-in amplifier. The multifrequency technique allows to measure the resonance curve of a vibrating object much faster than a conventional single frequency lock-in amplifier technique. Forks with resonance frequencies of 12 kHz and 16 kHz were excited and measured electro-mechanically either at a single frequency or at up to 40 different frequencies simultaneously around the same mechanical mode. The response of each fork was identical for both methods and validates the use of the multifrequency lock-in technique to probe properties of liquid helium at low fork velocities. Using both methods we measured the resonance frequency and drag of two 25-μ m-wide quartz tuning forks immersed in liquid ^4He in the temperature range from 4.2 K to 1.5 K at saturated vapour pressure. The damping and shift of resonance frequency experienced by both tuning forks at low velocities are well described by hydrodynamic contributions in the framework of the two-fluid model. The sensitivity of the 25-μ m-wide tuning forks is larger compared to similar 75-μ m-wide forks and in combination with the faster multifrequency lock-in technique could be used to improve thermometry in liquid ^4He. The multifrequency technique could also be used for studies of the onset of non-linear phenomena such as quantum turbulence and cavitation in superfluids.

  4. Search for sup 3 H, sub 3 He, and sub 4 He in D sub 2 -loaded titanium

    SciTech Connect

    Clarke, W.B.; Clarke, R.M. )

    1992-03-01

    In this paper a search is described for {sup 3}He, {sup 4}He, and tritium produced when D{sub 2} is absorbed by titanium sponge, or released when titanium deuteride is heated. The D{sub 2} is prepared from pre-nuclear-era D{sub 2}O, which has a tritium/deuterium (T/D) ratio of 1.8 {times} 10{sup {minus}15}. Two reservoirs of titanium sponge in a vacuum system attached to the inlet line of a mass spectrometer are heated to allow rapid transfer of D{sub 2} from one sponge to the other. Significant amounts of {sup 3}He and {sup 4}He are released only after the deuterium content is increased to reach TiD{sub 1.5} in one sponge. Then {sup 3}He and {sup 4}He are decreased as the D{sub 2} is transferred back and forth. When the titanium is loaded to a composition of TiD{sub 2.0}, {sup 3}He and {sup 4}He increase during the next two transfers, then decrease. When the D{sub 2} is replaced by H{sub 2}, then D{sub 2}-H{sub 2} (1:1), {sup 3}He and {sup 4}He decrease steadily, indicating that the transfer process causes partial release of {sup 3}He and {sup 4}He trapped in the titanium.

  5. Cross-checking groundwater age by 4He and 14C dating in a granite, Tono area, central Japan

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takuma; Nakata, Kotaro; Tomioka, Yuichi; Goto, Kazuyuki; Kashiwaya, Koki; Hama, Katsuhiro; Iwatsuki, Teruki; Kunimaru, Takanori; Takeda, Masaki

    2016-11-01

    Groundwater dating was performed simultaneously by the 4He and 14C methods in granite of the Tono area in central Japan. Groundwater was sampled at 30 packed-off sections of six 1000-m boreholes. 4He concentrations increased and 14C concentrations decreased along a groundwater flow path on a topographic gradient. 4He ages were calculated by using the in situ 4He production rate derived from the porosity, density, and U and Th content of the rock, neglecting external flux. 14C ages were calculated with a noncorrected model in which the initial 14C content was 100 percent of the modern radiocarbon level (Co = 100 pmC), a statistical model using the average 14C content of tritium-bearing samples (Co = 46.4 pmC), and a δ13C model based on the isotopic mass balance. Although the absolute 14C ages calculated by the models were different, the relative 14C ages were almost identical. The relative 14C ages were considered reliable because dissolved inorganic carbon has no significant geochemical reactions in granite. The relation between the 4He ages and the noncorrected 14C ages was [4He age] = 1.15 [14C age] + 7200 (R2 = 0.81), except in the discharge area. The slope of this relation was equivalent to unity, which indicates that the 4He accumulation rate is confirmed by the relative 14C ages. Moreover, the accumulated 3He/4He ratio was equivalent to that derived from the 6Li(α,n)3H reaction in granite. These results show that the accumulated He is of crustal origin, produced in situ without external flux, except in the discharge area. The intercept value of 7200 a implies that the 14C concentrations were diluted due to geochemical reactions. Tritium-bearing samples supported this result. Simultaneous measurements make it feasible to estimate the accumulation rate of 4He and initial dilution of 14C, which cannot be done with a single method. Cross-checking groundwater dating has the potential to provide more reliable groundwater ages. The circulation time of the

  6. {sup 4}He liquid-vapor interface below 1 K studied using x-ray reflectivity

    SciTech Connect

    Penanen, Konstantin; Fukuto, Masafumi; Heilmann, Ralf K.; Silvera, Isaac F.; Pershan, Peter S.

    2000-10-01

    The free surface of thin films of liquid helium adsorbed on a solid substrate has been studied using x-ray reflectivity. The film thickness and interfacial profile are extracted from the angular dependence of measured interference between signals reflected from the liquid-vapor and liquid-substrate interfaces. Polished silicon wafers, chemically cleaned and passivated, were used as substrates. Results are reported for measurements for {sup 4}He films 35 to 130 Aa thick in the temperature range 0.44 to 1.3 K. The 10%/90% interfacial width for temperature T=0.45 K varies from 5.3{+-}0.5 Aa for 36{+-}1.5 Aa thick films to 6.5{+-}0.5 Aa for 125{+-}1.5 Aa thick films. The profile width at zero temperature should not differ significantly from that measured at T=0.45 K. For T=1.22 K, the width is 7.8{+-}1.0 Aa.

  7. Determination of the effective kinematic viscosity for the decay of quasiclassical turbulence in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Gao, J.; Guo, W.; Vinen, W. F.

    2016-09-01

    The energy dissipation of quasiclassical homogeneous turbulence in superfluid 4He (He II) is controlled by an effective kinematic viscosity ν', which relates the energy decay rate d E /d t to the density of quantized vortex lines L as d E /d t =-ν'(κL ) 2 . The precise value of ν' is of fundamental importance in developing our understanding of the dissipation mechanism in He II, and it is also needed in many high-Reynolds-number turbulence experiments and model testing that use He II as the working fluid. However, a reliable determination of ν' requires the measurements of both E (t ) and L (t ) , which was never achieved. Here we discuss our study of the quasiclassical turbulence that emerges in the decay of thermal counterflow in He II above 1 K. We were able to measure E (t ) by using a recently developed flow-visualization technique and L (t ) via second-sound attenuation. We report the ν' values in a wide temperature range determined from a comparison of the time evolution of E (t ) and L (t ) .

  8. Time-resolved study of laser initiated shock wave propagation in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Garcia, Allan; Buelna, Xavier; Popov, Evgeny; Eloranta, Jussi

    2016-09-01

    Intense shock waves in superfluid 4He between 1.7 and 2.1 K are generated by rapidly expanding confined plasma from laser ablation of a metal target immersed in the liquid. The resulting shock fronts in the liquid with initial velocities up to ca. Mach 10 are visualized by time-resolved shadowgraph photography. These high intensity shocks decay within 500 ns into less energetic shock waves traveling at Mach 2, which have their lifetime in the microsecond time scale. Based on the analysis using the classical Rankine-Hugoniot theory, the shock fronts created remain in the solid phase up to 1 μs and the associated thermodynamic state appears outside the previously studied region. The extrapolated initial shock pressure of 0.5 GPa is comparable to typical plasma pressures produced during liquid phase laser ablation. A secondary shock originating from fast heat propagation on the metal surface is also observed and a lower limit estimate for the heat propagation velocity is measured as 7 × 104 m/s. In the long-time limit, the high intensity shocks turn into liquid state waves that propagate near the speed of sound.

  9. Third Sound Generation in Superfluid 4He Films Adsorbed on Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Iaia, Vito; Menachekanian, Emin; Williams, Gary

    2014-03-01

    A technique is developed for generating third sound in superfluid 4He films coating the surface of multiwall carbon nanotubes. Third sound is a thickness and temperature wave of the helium film, and in our case we detect the temperature oscillations with a carbon resistance bolometer. The nanotubes are packed in an annular resonator that is vibrated with a mechanical shaker assembly consisting of a permanent magnet mounted on springs, and surrounded by a superconducting coil. The coil is driven with an oscillating current, vibrating the cell at that frequency. Sweeping the drive frequency over the range 100-200 Hz excites the resonant third sound mode of the cell, seen as a high-Q signal in the FFT analysis of the bolometer signal. A problem with our original cell was that the mechanical drive would also shake the dilution refrigerator cooling the cell to low temperatures, and increasing the drive would start to heat up the refrigerator and the cell, which were rigidly coupled together. A new configuration now suspends the cell as a pendulum on a string, with thermal contact made by copper wires. Piezo sensor measurements show this reduces the vibration reaching the refrigerator by two orders of magnitude, which should allow measurements at lower temperatures.

  10. Operator evolution for ab initio electric dipole transitions of 4He

    DOE PAGESBeta

    Schuster, Micah D.; Quaglioni, Sofia; Johnson, Calvin W.; Jurgenson, Eric D.; Navartil, Petr

    2015-07-24

    A goal of nuclear theory is to make quantitative predictions of low-energy nuclear observables starting from accurate microscopic internucleon forces. A major element of such an effort is applying unitary transformations to soften the nuclear Hamiltonian and hence accelerate the convergence of ab initio calculations as a function of the model space size. The consistent simultaneous transformation of external operators, however, has been overlooked in applications of the theory, particularly for nonscalar transitions. We study the evolution of the electric dipole operator in the framework of the similarity renormalization group method and apply the renormalized matrix elements to the calculationmore » of the 4He total photoabsorption cross section and electric dipole polarizability. All observables are calculated within the ab initio no-core shell model. Furthermore, we find that, although seemingly small, the effects of evolved operators on the photoabsorption cross section are comparable in magnitude to the correction produced by including the chiral three-nucleon force and cannot be neglected.« less

  11. Theory of neutron scattering from thermally excited quasiparticles in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Griffin, A.; Talbot, E.

    1981-11-01

    We present the first detailed theoretical study of the inelastic neutron scattering contribution Sth(Q-->,ω) from thermally excited quasiparticles in superfluid 4He, with emphasis on the low-Q collisionless limit. In the temperature region where rotons are the dominant excitation, our results for Sth(Q-->,ω) scale with Landau's normal fluid density. We argue that Sth(Q-->,ω) is the origin of the broad temperature-dependent continuum which Woods and Svensson (1978) have observed at temperatures above about 1.7 K. Our specific model calculations of Sth(Q-->,ω) are based on evaluating the regular part of the longitudinal momentum current-current correlation function within the Bogoliubov approximation, but the experimental quasiparticle (roton) spectrum is used in our numerical calculations. Our expression satisfies the normal fluid f-sum rule in the long-wavelength collisionless limit and is in essential agreement with the general picture suggested by Pines and Nozières in 1964. Our present theory involves several approximations which probably limit its validity to Q<~0.5 Å-1. Some generalizations to deal with the larger values of Q studied by Woods and Svensson are briefly discussed.

  12. Path integral studies of the rotations of methane and its heavier isotopomers in 4He nanoclusters.

    PubMed

    Markovskiy, N D; Mak, C H

    2009-08-13

    Path integral Monte Carlo simulations have been carried out to study the rotations of a methane molecule and its heavier isotopomers inside a small cluster of 4He atoms at 0.3 K in order to determine how the renormalization in the methane's rotational constant is related to the quantum statistics and superfluidity of the helium shell. By changing the mass of the hydrogens and systematically varying the moment of inertia of the methane, we were able to study the effects of its rotations on the quantum statistics of the helium atoms and their countereffects on the methane's effective rotational constant. The renormalized rotational constant depends strongly on the intrinsic moment of inertia of the methane. A heavy probe favors strong templating of the helium density as well as a large renormalization in the probe's rotational constant, but a light probe shows almost no effect on the shell density or the effective rotational constant. These results suggest that in order to fully understand the superfluidity of the helium shell, the probe must be treated as an integral part of the system. We rationalize the findings in terms of a rotational smearing effect and suggest that there is no clearly quantifiable relationship between the superfluid fraction of the shell and the renormalized rotational constant of the probe for cases where the probe molecule is either light or has weak anisotropic interactions with the helium atoms. PMID:19618956

  13. Polarized liquid3He in a4He circulating dilution refrigerator

    NASA Astrophysics Data System (ADS)

    Rodrigues, Alexandre; Vermeulen, Gerard

    1995-10-01

    We have used a4He circulating dilution refrigerator to produce cold liquid3He with a steady state out-of-equilibrium nuclear spin polarization. Polarizations on the order of 15% (more than 7 times higher than the equilibrium polarization in the external field of 6.6 T) have been obtained in the mixing chamber of the refrigerator at temperatures between 10 and 15 mK. The polarization is enhanced at high pressure because the molar susceptibility of concentrated3He is larger than that of the dilute phase. The polarization exchange between the dilute and concentrated phases (in direct contact in the heat exchanger of the refrigerator) amplifies the enhancement. The polarization diminishes below a pressure of 2.6 bar. This allows us to scale and reinterpret susceptibility data of the dilute phase1 in combination with the effective mass deduced from osmotic pressure measurements2. We find 1+F{0/a} = 0.89±1% on the phase separation line in the pressure range 0 20 bar.

  14. Fluid pinch-off in superfluid and normal {sup 4}He

    SciTech Connect

    Burton, J. C.; Rutledge, J. E.; Taborek, P.

    2007-03-15

    We present frames from high-speed videos of the pinch-off of liquid {sup 4}He droplets. The temperature of the fluid droplets ranged from 1.33 K to 4.8 K, and the size of the drops was proportional to the temperature-dependent capillary length. We observed no qualitative difference between pinch-off in the normal and superfluid states. In both cases, the shape of the fluid in the final stages of pinch-off resembles a cone piercing a sphere, which is typical of other low-viscosity fluids. The evolution of the minimum neck radius r{sub min} can be characterized by power laws r{sub min}{proportional_to}{tau}{sup n}, where {tau} is the time remaining until pinch-off occurs. In the regime near pinch-off, the data from image analysis are consistent with n=2/3. The data at the beginning of the pinch process when the neck is of the order of the capillary length are also described by n=2/3, but with a different proportionality factor. There is an intermediate crossover regime characterized by n=2/5.

  15. Copper dimer interactions on a thermomechanical superfluid {sup 4}He fountain

    SciTech Connect

    Popov, Evgeny; Eloranta, Jussi

    2015-05-28

    Laser induced fluorescence imaging and frequency domain excitation spectroscopy of the copper dimer (B{sup 1}Σ{sub g}{sup +}←X{sup 1}Σ{sub u}{sup +}) in thermomechanical helium fountain at 1.7 K are demonstrated. The dimers penetrate into the fountain provided that their average propagation velocity is ca. 15 m/s. This energy threshold is interpreted in terms of an imperfect fountain liquid-gas interface, which acts as a trap for low velocity dimers. Orsay-Trento density functional theory calculations for superfluid {sup 4}He are used to characterize the dynamics of the dimer solvation process into the fountain. The dimers first accelerate towards the fountain surface and once the surface layer is crossed, they penetrate into the liquid and further slow down to Landau critical velocity by creating a vortex ring. Theoretical lineshape calculations support the assignment of the experimentally observed bands to Cu{sub 2} solvated in the bulk liquid. The vibronic progressions are decomposed of a zero-phonon line and two types of phonon bands, which correlate with solvent cavity interface compression (t < 200 fs) and expansion (200 < t < 500 fs) driven by the electronic excitation. The presented experimental method allows to perform molecular spectroscopy in bulk superfluid helium where the temperature and pressure can be varied.

  16. Evidence for intertwined superfluid and density wave order in two dimensional 4He

    NASA Astrophysics Data System (ADS)

    Saunders, John

    2015-03-01

    We report the identification of a new state of quantum matter with intertwined superfluid and density wave order in a system of two dimensional bosons subject to a triangular lattice potential. Using a torsional oscillator we have measured the response of the second atomic layer of 4He adsorbed on the surface of graphite over a wide temperature range down to 2 mK. Superfluidity is observed over a narrow range of film densities, emerging suddenly and collapsing towards a quantum critical point, near to layer completion where a Mott insulating phase is predicted to form. The unusual temperature dependence of the superfluid density in the T --> 0 limit and the absence of a clear superfluid onset temperature are explained, self-consistently, by an ansatz for the excitation spectrum, reflecting density wave order, and a quasi-condensate wavefunction breaking both gauge and translational symmetry. In collaboration with Jan Nyeki, Anastasia Phillis, Andrew Ho, Derek Lee, Piers Coleman, Jeevak Parpia, Brian Cowan. Supported by EPSRC (U.K) EP/H048375/1.

  17. Medium Modifications from {sup 4}He(e-vector,e'p-vector){sup 3}H

    SciTech Connect

    Malace, S.; Paolone, M.; Strauch, S.

    2008-10-13

    Polarization transfer in quasi-elastic nucleon knockout is sensitive to the properties of the nucleon in the nuclear medium, including possible modification of the nucleon form factor and/or spinor. In our recently completed experiment E03-104 at Jefferson Lab we measured the proton recoil polarization in the {sup 4}He(e-vector,e'p-vector){sup 3}H reaction at a Q{sup 2} of 0.8 (GeV/c){sup 2} and 1.3 (GeV/c){sup 2} with unprecedented precision. These data complement earlier data between 0.4 and 2.6 (GeV/c){sup 2} from both Mainz and Jefferson Lab. The measured ratio of polarization-transfer coefficients differs from a fully relativistic calculation, favoring either the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model or strong charge-exchange final-state interactions. The measured induced polarizations agree well with the fully relativistic calculation and indicate that these strong final-state interactions may not be applicable.

  18. Improvement of the Spatial Amplitude Isotropy of a ^4He Magnetometer Using a Modulated Pumping Beam

    NASA Astrophysics Data System (ADS)

    Chéron, B.; Gilles, H.; Hamel, J.; Moreau, O.; Noël, E.

    1997-08-01

    Optically pumped magnetometers are scalar magnetometers. Contrary to vectoriel magnetometers, they measure the total magnetic field whatever the direction of the sensor. However, for some orientations of the magnetometer with respect to the magnetic field direction, the resonant signal vanishes and the measurement is impossible. In this paper we present a simple solution to reduce the amplitude spatial anisotropy and apply it to a ^4He magnetometer developed in our Laboratory. Les magnétomètres à pompage optique sont des magnétomètres scalaires. Contrairement aux magnétomètres vectoriels, ils mesurent le module du champ magnétique quelle que soit l'orientation du capteur dans l'espace. Cependant, pour certaines orientations du magnétomètre par rapport à la direction du champ à mesurer, l'amplitude du signal de résonance s'annule et la mesure devient impossible. Dans cet article, nous présentons une solution simple pour réduire l'anisotropie spatiale d'amplitude et nous l'appliquons à un magnétomètre à hélium-4 développé dans notre Laboratoire.

  19. One-Dimensional Liquid ^{4}He: Dynamical Properties beyond Luttinger-Liquid Theory.

    PubMed

    Bertaina, G; Motta, M; Rossi, M; Vitali, E; Galli, D E

    2016-04-01

    We compute the zero-temperature dynamical structure factor of one-dimensional liquid ^{4}He by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model. PMID:27081985

  20. 4He+n+n continuum within an ab initio framework

    DOE PAGESBeta

    Romero-Redondo, Carolina; Quaglioni, Sofia; Navratil, Petr; Hupin, Guillaume

    2014-07-16

    In this study, the low-lying continuum spectrum of the 6He nucleus is investigated for the first time within an ab initio framework that encompasses the 4He+n+n three-cluster dynamics characterizing its lowest decay channel. This is achieved through an extension of the no-core shell model combined with the resonating-group method, in which energy-independent nonlocal interactions among three nuclear fragments can be calculated microscopically, starting from realistic nucleon-nucleon interactions and consistent ab initio many-body wave functions of the clusters. The three-cluster Schrödinger equation is solved with three-body scattering boundary conditions by means of the hyperspherical-harmonics method on a Lagrange mesh. Using amore » soft similarity-renormalization-group evolved chiral nucleon-nucleon potential, we find the known Jπ = 2+ resonance as well as a result consistent with a new low-lying second 2+ resonance recently observed at GANIL at ~2.6 MeV above the He6 ground state. We also find resonances in the 2–, 1+, and 0– channels, while no low-lying resonances are present in the 0+ and 1– channels.« less

  1. Generalized theory of double-resonance optical pumping of {sup 4}He

    SciTech Connect

    Plante, Michael K.; MacFarlane, Duncan L.; McGregor, Douglas D.; Slocum, Robert E.; Sampson, William M.; Brown, Andy W.

    2010-07-15

    We present extensions to the theory of double-resonance laser pumping of {sup 4}He in the context of magnetometer instrumentation. This extended theory allows for arbitrary optical polarization, magnetic resonance (H{sub 1}) coil orientation, and overall instrument orientation relative to the ambient magnetic field. Steady-state solutions are presented for portions of the extended parameter space. These calculations are used to analyze the shot-noise-limited sensitivities for helium magnetometers for selected parameter values, and we find that linearly polarized light can have a relatively simple orientational dependence for a particular choice of angle between the H{sub 1} coils and the light polarization vector. Calculations are also compared to experimentally measured magnetic resonance curves, and a shot-noise limit on sensitivity of 6 fT/{radical}(Hz) is determined for a particular magnetometer apparatus using a cell 2.4 cm in diameter and 7.5 cm in length. This extended theory can be utilized to select optimal operational parameter values and obtain ideal sensitivities for helium magnetometers.

  2. Electromagnetic and neutral-weak response functions of 4He and 12C

    NASA Astrophysics Data System (ADS)

    Lovato, A.; Gandolfi, S.; Carlson, J.; Pieper, Steven C.; Schiavilla, R.

    2015-06-01

    Background: A major goal of nuclear theory is to understand the strong interaction in nuclei as it manifests itself in terms of two- and many-body forces among the nuclear constituents, the protons and neutrons, and the interactions of these constituents with external electroweak probes via one- and many-body currents. Purpose: The objective of the present work is to calculate the quasielastic electroweak response functions in light nuclei within the realistic dynamical framework outlined above. These response functions determine the inclusive cross section as function of the lepton momentum and energy transfers. Methods: Their ab initio calculation is a very challenging quantum many-body problem, since it requires summation over the entire excitation spectrum of the nucleus and inclusion in the electroweak currents of one- and many-body terms. Green's functions Monte Carlo methods allow one to circumvent both difficulties by computing the response in imaginary time (the so-called Euclidean response) and hence summing implicitly over the bound and continuum states of the nucleus, and by implementing specific algorithms designed to deal with the complicated spin-isospin structure of nuclear many-body operators. Results: Theoretical predictions for 4He and 12C, confirmed by experiment in the electromagnetic case, show that two-body currents generate excess transverse strength from threshold to the quasielastic to the dip region and beyond. Conclusions: These results challenge the conventional picture of quasielastic inclusive scattering as being largely dominated by single-nucleon knockout processes.

  3. Interaction of ions, atoms, and small molecules with quantized vortex lines in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Mateo, David; Eloranta, Jussi; Williams, Gary A.

    2015-02-01

    The interaction of a number of impurities (H2, Ag, Cu, Ag2, Cu2, Li, He3 + , He* (3S), He2∗ (3Σu), and e-) with quantized rectilinear vortex lines in superfluid 4He is calculated by using the Orsay-Trento density functional theory (DFT) method at 0 K. The Donnelly-Parks (DP) potential function binding ions to the vortex is combined with DFT data, yielding the impurity radius as well as the vortex line core parameter. The vortex core parameter at 0 K (0.74 Å) obtained either directly from the vortex line geometry or through the DP potential fitting is smaller than previously suggested but is compatible with the value obtained from re-analysis of the Rayfield-Reif experiment. All of the impurities have significantly higher binding energies to vortex lines below 1 K than the available thermal energy, where the thermally assisted escape process becomes exponentially negligible. Even at higher temperatures 1.5-2.0 K, the trapping times for larger metal clusters are sufficiently long that the previously observed metal nanowire assembly in superfluid helium can take place at vortex lines. The binding energy of the electron bubble is predicted to decrease as a function of both temperature and pressure, which allows adjusting the trap depth for either permanent trapping or to allow thermally assisted escape. Finally, a new scheme for determining the trapping of impurities on vortex lines by optical absorption spectroscopy is outlined and demonstrated for He*.

  4. Interaction of Ions, Atoms and Small Molecules with Quantized Vortex Lines in Superfluid 4He

    NASA Astrophysics Data System (ADS)

    Eloranta, Jussi; Matteo, David; Williams, Gary

    2015-03-01

    The interaction of a number of impurities (H2, Ag, Cu, Ag2, Cu2, Li, He3+,He* (3 S), He2*(3Σu) and e-) with quantized rectilinear vortex lines in superfluid 4He is calculated using density functional methods at 0 K. The technique yields the impurity radius as well as the vortex line core parameter. The core parameter at 0 K (0.74 Å) obtained either directly from the vortex line geometry or from the trapping potential fitting is smaller than previously suggested but is compatible with a re-analysis of the Rayfield-Reif experiment. All of the impurities have significant binding energies to the vortex lines below 1 K where the thermally assisted escape process becomes very inefficient. Even at higher temperatures the trapping times, especially for larger clusters, are sufficiently long that the observed metal nanowire assembly in superfluid helium can take place at vortex lines. The binding energy of the electron bubble is predicted to decrease as a function of both temperature and pressure, which allows adjusting the trap depth for either permanent trapping or thermally assisted escape. A new scheme for determining the trapping of impurities on vortex lines by optical absorption spectroscopy is outlined and demonstrated for He*. Work supported by the NSF, Grants CHE-1262306 and DMR-1205734, and the Interdisciplinary Research Institute for the Sciences.

  5. One-Dimensional Liquid ^{4}He: Dynamical Properties beyond Luttinger-Liquid Theory.

    PubMed

    Bertaina, G; Motta, M; Rossi, M; Vitali, E; Galli, D E

    2016-04-01

    We compute the zero-temperature dynamical structure factor of one-dimensional liquid ^{4}He by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model.

  6. Electron screening and stellar rates in the {sup 3}He({sup 3}He,2p){sup 4}He and {sup 3}He(d,p){sup 4}He fusion reactions

    SciTech Connect

    Messahel, L.; Ouichaoui, S.; Belhout, A.; Fouka, M.; Trabelsi, A.

    2008-05-12

    The astrophysical S(E) factor experimental data available over the energy region E (C.M.)<1.0 MeV for the {sup 3}He({sup 3}He,2p){sup 4}He and {sup 3}He(d,p){sup 4}He fusion reactions are analyzed using a polynomial expression and the R-Matrix formalism, respectively. The reaction thermonuclear rates for bare nuclei are determined and compared to previous ones after a precise assessment of the electron screening factors. New level parameter values are deduced for the {sup 5}Li nucleus.

  7. 190Pt-4He age of PGE ores in the Alkaline-Ultramafic Kondyor Massif (Khabarovsk District, Russia)

    NASA Astrophysics Data System (ADS)

    Mochalov, A. G.; Yakubovich, O. V.; Bortnikov, N. S.

    2016-08-01

    A new 190Pt-4He method for dating isoferroplatinum has been developed at the Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences. Here we publish the first results of dating of isoferroplatinum from the main mineralogical and geochemical types of PGE mineralization in dunite. The obtained 190Pt-4He age of isoferroplatinum is 129 ± 6 Ma. The gained 190Pt-4He age of isoferroplatinum specimens of different genesis (magmatic, fluid-metamorphogenic, and metasomatic) from the Kondyor Massif indicates that the PGM mineralization took place synchronously and successively with evolution of primarily picrite, followed by subalkaline and alkaline melts of the Mesozoic tectonic-magmatic activation of the Aldan Shield.

  8. Suppression of Freezing and Emergence of a Novel Ordered State in 4He Confined in a Nano - porous Material

    SciTech Connect

    Yamamoto, K.; Shibayama, Y.; Shirahama, K.

    2006-09-07

    Confinement of 4He in a porous material with nanometer - size pores suppresses both the freezing and superfluidity. In our previous investigation of superfluid density of 4He confined in a porous Gelsil glass which has pores of 2.5 nm in diameter, it was demonstrated that the superfluidity is greatly suppressed by pressurization. In order to explore the overall P - T phase diagram, we study the liquid - solid coexistence line. The freezing pressure is elevated up to about 3.4 MPa and independent of temperature below 1.3 K. Along with the previous measurement of superfluid density these features indicate that a nonsuperfluid phase exists next to the solid phase. The flat freezing curve indicates that this nonsuperfluid phase has small entropy as well as that of solid. Therefore the nonsuperfluid phase is possibly a novel ordered state, in which the global phase coherence is destroyed by strong correlation between 4He atoms and/or by random potential.

  9. Bare-nucleus astrophysical factor of the 3He(d,p)4He reaction via the ``Trojan horse'' method

    NASA Astrophysics Data System (ADS)

    La Cognata, M.; Spitaleri, C.; Tumino, A.; Typel, S.; Cherubini, S.; Lamia, L.; Musumarra, A.; Pizzone, R. G.; Rinollo, A.; Rolfs, C.; Romano, S.; Schürmann, D.; Strieder, F.

    2005-12-01

    The 3He(d,p)4He reaction has been studied from Ec.m.=600 keV down to astrophysical energies by means of the “Trojan horse” method using the 6Li(3He,pα)4He three-body reaction at Elab=5 and 6 MeV. Coincidence spectra were measured in kinematic conditions favoring the quasifree 3He+2H process. The bare astrophysical factor Sb(E) for the 3He(d,p)4He reaction was extracted from the three-body cross section in the modified plane-wave Born approximation. Comparison with the Sb extrapolation from the free two-body data is presented. The independent estimate of the screening potential as obtained with the present work seems to confirm the theoretical adiabatic limit.

  10. The nature of superfluidity and Bose-Einstein condensation: From liquid 4He to dilute ultracold atomic gases (Review Article)

    NASA Astrophysics Data System (ADS)

    Vilchynskyy, S. I.; Yakimenko, A. I.; Isaieva, K. O.; Chumachenko, A. V.

    2013-09-01

    We present a brief overview of crucial historical stages in creation of superfluidity theory and of the current state of the microscopic theory of superfluid 4He. We pay special attention to the role of Bose-Einstein condensates (BECs) in understanding of physical mechanisms of superfluidity and identification of quantum mechanical structure of 4He superfluid component below λ-point, in particular—the possibility that at least two types of condensates may appear and coexist simultaneously in superfluid 4He. In this context we discuss the properties of the binary mixtures of BECs and types of excitations, which may appear due to intercomponent interaction in such binary mixtures of condensates. We also discuss current status of investigations of persistent currents in toroidal optical traps and present an outlook of our recent findings on this subject.

  11. Interaction of ions, atoms, and small molecules with quantized vortex lines in superfluid {sup 4}He

    SciTech Connect

    Mateo, David; Eloranta, Jussi; Williams, Gary A.

    2015-02-14

    The interaction of a number of impurities (H{sub 2}, Ag, Cu, Ag{sub 2}, Cu{sub 2}, Li, He{sub 3}{sup +}, He{sup *} ({sup 3}S), He{sub 2}{sup ∗} ({sup 3}Σ{sub u}), and e{sup −}) with quantized rectilinear vortex lines in superfluid {sup 4}He is calculated by using the Orsay-Trento density functional theory (DFT) method at 0 K. The Donnelly-Parks (DP) potential function binding ions to the vortex is combined with DFT data, yielding the impurity radius as well as the vortex line core parameter. The vortex core parameter at 0 K (0.74 Å) obtained either directly from the vortex line geometry or through the DP potential fitting is smaller than previously suggested but is compatible with the value obtained from re-analysis of the Rayfield-Reif experiment. All of the impurities have significantly higher binding energies to vortex lines below 1 K than the available thermal energy, where the thermally assisted escape process becomes exponentially negligible. Even at higher temperatures 1.5-2.0 K, the trapping times for larger metal clusters are sufficiently long that the previously observed metal nanowire assembly in superfluid helium can take place at vortex lines. The binding energy of the electron bubble is predicted to decrease as a function of both temperature and pressure, which allows adjusting the trap depth for either permanent trapping or to allow thermally assisted escape. Finally, a new scheme for determining the trapping of impurities on vortex lines by optical absorption spectroscopy is outlined and demonstrated for He{sup *}.

  12. Second-sound studies of coflow and counterflow of superfluid {sup 4}He in channels

    SciTech Connect

    Varga, Emil; Skrbek, L.; Babuin, Simone

    2015-06-15

    We report a comprehensive study of turbulent superfluid {sup 4}He flow through a channel of square cross section. We study for the first time two distinct flow configurations with the same apparatus: coflow (normal and superfluid components move in the same direction), and counterflow (normal and superfluid components move in opposite directions). We realise also a variation of counterflow with the same relative velocity, but where the superfluid component moves while there is no net flow of the normal component through the channel, i.e., pure superflow. We use the second-sound attenuation technique to measure the density of quantised vortex lines in the temperature range 1.2 K ≲ T ≲ T{sub λ} ≈ 2.18 K and for flow velocities from about 1 mm/s up to almost 1 m/s in fully developed turbulence. We find that both the steady-state and temporal decay of the turbulence significantly differ in the three flow configurations, yielding an interesting insight into two-fluid hydrodynamics. In both pure superflow and counterflow, the same scaling of vortex line density with counterflow velocity is observed, L∝V{sub cf}{sup 2}, with a pronounced temperature dependence; in coflow instead, the vortex line density scales with velocity as L ∝ V{sup 3/2} and is temperature independent; we provide theoretical explanations for these observations. Further, we develop a new promising technique to use different second-sound resonant modes to probe the spatial distribution of quantised vortices in the direction perpendicular to the flow. Preliminary measurements indicate that coflow is less homogeneous than counterflow/superflow, with a denser concentration of vortices between the centre of the channel and its walls.

  13. Helium isotopes in early Iceland plume picrites: Constraints on the composition of high 3He/ 4He mantle

    NASA Astrophysics Data System (ADS)

    Starkey, Natalie A.; Stuart, Finlay M.; Ellam, Robert M.; Fitton, J. Godfrey; Basu, Sudeshna; Larsen, Lotte M.

    2009-01-01

    A detailed study of the geochemistry of a new suite of early Iceland plume picrites shows that extremely high 3He/ 4He ratios (up to 50 Ra) are found in picrites from Baffin Island and West Greenland. High 3He/ 4He picrites display a wide range in 87Sr/ 86Sr (0.70288-0.70403), 143Nd/ 144Nd (0.51288-0.51308) and incompatible trace element ratios (e.g. La/Sm n = 0.5-1.6). These overlap the complete range of compositions of mid-ocean ridge basalts and most northern hemisphere ocean island basalts, including Iceland. Crustal contamination modelling in which high-grade Proterozoic crustal basement rocks for the region are mixed with a depleted parent cannot account for the trend displayed by the Baffin Island and West Greenland picrites. This rules out the possibility that the incompatible trace element, Sr and Nd isotope range of the high 3He/ 4He picrites is due to crustal contamination. The compositional range at high 3He/ 4He is also inconsistent with derivation from a primordial-He-rich reservoir that is a residue of ancient mantle depletion. This implies that the composition of the high 3He/ 4He mantle cannot be determined simply by extrapolating ocean island basalt He-Sr-Nd-Pb-Os isotope data. The apparent decoupling of He from trace element and lithophile radiogenic isotope tracers is difficult to attain by simple mixing of a high-[He], high 3He/ 4He reservoir with various depleted and enriched He-poor mantle reservoirs. The possibility that primordial He has diffused into a reservoir with a composition typical of convecting upper mantle cannot be ruled out. If so, the process must have occurred after the development of existing mantle heterogeneity, and requires the existence of a deep, primordial He-rich reservoir.

  14. Pole approximation validation in the study of the {sup 6}Li(d,{alpha}){sup 4}He reaction

    SciTech Connect

    Pizzone, R. G.; Kiss, G. G.; Spitaleri, C.; Lamia, L.; Cherubini, S.; La Cognata, M.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Burjan, V.; Hons, Z.; Kroha, V.; Mrazek, J.; Piskor, S.; Li, C.; Tumino, A.

    2010-11-24

    The Trojan Horse Method (THM) was applied to the {sup 3}He+{sup 6}Li interaction in order to investigate the quasi-free {sup 6}Li(d,{alpha}){sup 4}He reaction. The experiment was performed at 17 MeV at the Cyclotron Institute of the Czech Academy of Science. The extracted {sup 6}Li(d,{alpha}){sup 4}He quasi-free cross-section was compared with the behavior of direct data. A good agreement between data sets shows up throughout the energy range investigated, providing a very important validity test of the pole approximation for the THM above the Coulomb barrier.

  15. Mass Flux Stability in the Presence of Temperature Excursions and Perturbations in Solid ^3He-^4He Mixtures

    NASA Astrophysics Data System (ADS)

    Vekhov, Ye.; Hallock, R. B.

    2016-11-01

    The DC superfluid ^4He mass flux through a cell filled with solid ^4He diluted by ppm amounts of ^3He is susceptible to flux changes when perturbations of the solid sample are imposed. We report on the details of the reproducibility of the flux following excursions in temperature and cryostat helium transfer-induced apparatus vibration, particularly including excursions to temperatures above which the flux is immeasurably small. And we report on behavior following an annealing, partial melting, and re-freezing of the sample at temperatures and pressures close to and on the melting curve.

  16. Temperature dependence of S(Q,ω) in liquid 4He under pressure

    NASA Astrophysics Data System (ADS)

    Talbot, E. F.; Glyde, H. R.; Stirling, W. G.; Svensson, E. C.

    1988-12-01

    The temperature dependence of the dynamic form factor, S(Q,ω), of liquid 4He at p=20 bars has been determined by inelastic neutron scattering measurements. Two wave vectors, Q=1.13 Å-1 and Q=2.03 Å-1, corresponding to the maxon and roton regions of the phonon-roton dispersion curve, were studied over a wide range of energy transfer, ħω. Based on previous data at SVP, Woods and Svensson proposed that S(Q,ω) could be represented as a sum of two components, one proportional to the superfluid density, ρS(T), and one proportional to the normal density ρN(T). The component proportional to ρS(T) contained the sharp one-phonon peak which vanished at T=Tλ. The aim here is, firstly, to present data on the temperature dependence of S(Q,ω) at 20 bars and, secondly, to explore whether or not the Woods-Svensson decomposition of S(Q,ω) holds at higher pressure. At 20 bars and for the Q values investigated here, we find that the sharp peak of S(Q,ω) does indeed decrease rapidly in intensity as T increases and the corresponding excitation either vanishes or changes abruptly in character at Tλ. The sharp nature of the one-phonon peak Tλ does therefore appear to be associated with superfluidity or a Bose condensate at these Q values. However, the weight of the one-phonon peak does not scale as ρS(T) and subtracting a contribution proportional to ρN(T) from S(Q,ω) leads to negative values of the superfluid component of S(Q,ω) at low ω. Thus S(Q,ω) at 20 bars does not naturally separate into a part proportional to ρS and one proportional to ρN. We also explore the consequences of a simple subtraction of the multiphonon component, assumed temperature independent, as an alternative method of extracting one-phonon parameters from the total scattering intensity. The values of the one-phonon properties such as the frequency and the lifetime obtained by the simple multiphonon subtraction method also show a marked change at Tλ.

  17. Spectroscopic information of 6Li from elastic scattering of deuterons, 3He and 4He by 6Li

    NASA Astrophysics Data System (ADS)

    Amar, A.

    2014-07-01

    The elastic scattering of deuterons, 3He and 4He on 6Li at different incident energies have been analyzed in the framework of the optical model (OM) using ECIS88 as well as SPI GENOA codes. The optical potential parameters were extracted in the phenomenological treatment. A good agreement between theoretical and experimental differential cross-sections was obtained in whole angular range. Parameters for real part of potential have been also calculated microscopically with double-folding model for the d, 3He and 4He scattering, respectively, using DFPOT code. The elastic transfer mechanism has been studied by coupled reaction channel (CRC) method using FRESCO code. Spectroscopic amplitudes of 6Li ≡ t + 3He and 6Li ≡ α + d configurations have been extracted from d, 3He and 4He scattering on 6Li at wide energy range. A comparison between spectroscopic amplitudes obtained from deuteron and α elastically scattering from 6Li has been made. The extracted spectroscopic amplitudes of 6Li ≡ 4He + d(SF = SA2) from 6Li(d, 6Li)d and 6Li(α, 6Li)α are not the same as expected theoretically.

  18. Incorporating 3-D parent nuclide zonation for apatite 4He/3He thermochronometry: An example from the Appalachian Mountains

    NASA Astrophysics Data System (ADS)

    Fox, Matthew; McKeon, Ryan E.; Shuster, David L.

    2014-11-01

    ability to constrain km-scale exhumation with apatite 4He/3He thermochronometry is well established and the technique has been applied to a range of tectonic and geomorphic problems. However, multiple sources of uncertainty in specific crystal characteristics limit the applicability of the method, especially when geologic problems require identifying small perturbations in a cooling path. Here we present new 4He/3He thermochronometric data from the Appalachian Mountains, which indicate significant parent nuclide zonation in an apatite crystal. Using LA-ICPMS measurements of U and Th in the same crystal, we design a 3-D model of the crystal to explore the effects of intracrystal variability in radiation damage accumulation. We describe a numerical approach to solve the 3-D production-diffusion equation. Using our numerical model and a previously determined time temperature path for this part of the Appalachians, we find excellent agreement between predicted and observed 4He/3He spectra. Our results confirm this time-temperature path and highlight that for complex U and Th zonation patterns, 3-D numerical models are required to infer an accurate time-temperature history. In addition, our results provide independent and novel evidence for a radiation damage control on diffusivity. The ability to exploit intracrystal differences in 4He diffusivity [i.e., temperature sensitivity) greatly increases the potential to infer complex thermal histories.

  19. 4He in Modern Cape Verde Corals: A High-Resolution Proxy Record of N. African Climate

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Kreycik, P.; Schrag, D. P.

    2005-12-01

    Mineral dust from arid and semi arid regions is an important component of climatic processes. The amount of dust emitted off continents is intimately linked with precipitation, which may itself be linked to atmospheric circulation driven by oceanic sea surface temperatures. Hence, reconstructing dust fluxes off continents with sub-decadal resolution can provide us with fundamental insights into feedbacks in the climate system. Unfortunately, such high-resolution dust flux records prior to the establishment of the Barbados dust sampling station are largely lacking. Here we show that 4He concentrations in annual bands in corals provides a high-resolution, reliable, and robust proxy record of dust flux from continents. Some traces phases in dust, such as zircons, are rich in U and Th and thus have extremely high concentrations of 4He. As some fraction of the dust settles out of the atmosphere and through the water column, corals incorporate the dust in their skeletons through filter feeding. Since the alpha stopping distance is greater than the particle size of wind blown dust, the mineral grains will not accumulate radiogenic helium after the dust is incorporated into the corals. We have measured the 4He concentration in annual bands dating back to 1960's in a modern coral that was collected in 1996 off the island of Sal, part of the Cape Verde archipelago. The coral is therefore, situated close to, and directly west of the dust source in the Sudano-Sahel region of the African continent. The 4He record from the coral shows remarkable similarity with the record from the Barbados dust sampling station. There is a continuous increase in 4He baseline values by a factor of two from the mid 1960's to the early 1990's as well as two pronounced peaks in the early 1970's and mid 1980's associated with severe drought in the Sudano-Sahel region. Our proxy record from the Cape Verde Island demonstrates that 4He concentrations in corals can be used reliably to reconstruct dust

  20. The helium flux from the continents and ubiquity of low-3He/4He recycled crust and lithosphere

    NASA Astrophysics Data System (ADS)

    Day, James M. D.; Barry, Peter H.; Hilton, David R.; Burgess, Ray; Pearson, D. Graham; Taylor, Lawrence A.

    2015-03-01

    New helium isotope and trace-element abundance data are reported for pyroxenites and eclogites from South Africa, Siberia, and the Beni Bousera Massif, Morocco that are widely interpreted to form from recycled oceanic crustal protoliths. The first He isotope data are also presented for Archaean peridotites from the Kaapvaal (South Africa), Slave (Canada), and Siberian cratons, along with recently emplaced off-craton peridotite xenoliths from Kilbourne Hole, San Carlos (USA) and Vitim (Siberia), to complement existing 3He/4He values obtained for continental and oceanic peridotites. Helium isotope compositions of peridotite xenoliths vary from 7.3 to 9.6 RA in recently (<10 kyr) emplaced xenoliths, to 0.05 RA in olivine from cratonic peridotite xenoliths of the 1179 Ma Premier kimberlite, South Africa. The helium isotope compositions of the peridotites can be explained through progressive sampling of 4He produced from radiogenic decay of U and Th in the mineral lattice in the older emplaced peridotite xenoliths. Ingrowth of 4He is consistent with generally higher 4He concentrations measured in olivine from older emplaced peridotite xenoliths relative to those from younger peridotite xenoliths. Collectively, the new data are consistent with pervasive open-system behaviour of He in peridotite xenoliths from cratons, mobile belts and tectonically-active regions. However, there is probable bias in the estimate of the helium isotope composition of the continental lithospheric mantle (6.1 ± 2.1 RA), since previously published databases were largely derived from peridotite xenoliths from non-cratonic lithosphere, or phenocrysts/xenocrysts obtained within continental intraplate alkaline volcanics that contain a contribution from asthenospheric sources. Using the new He isotope data for cratonic peridotites and assuming that significant portions (>50%) of the Archaean and Proterozoic continental lithospheric mantle are stable and unaffected by melt or fluid infiltration on

  1. Ab initio study of {sup 2}H(d,{gamma}){sup 4}He, {sup 2}H(d,p){sup 3}H, and {sup 2}H(d,n){sup 4}He reactions and the tensor force

    SciTech Connect

    Arai, K.; Aoyama, S.; Suzuki, Y.; Descouvemont, P.; Baye, D.

    2012-11-12

    The {sup 2}H(d,p){sup 3}H, {sup 2}H(d,n){sup 3}He, and {sup 2}H(d,{gamma}){sup 4}He reactions at low energies are studied with realistic nucleon-nucleon interactions in an ab initio approach. The obtained astrophysical S-factors are all in very good agreement with experiment. The most important channels for both transfer and radiative capture are all found to dominate thanks to the tensor force.

  2. Communication: A combined periodic density functional and incremental wave-function-based approach for the dispersion-accounting time-resolved dynamics of {sup 4}He nanodroplets on surfaces: {sup 4}He/graphene

    SciTech Connect

    Lara-Castells, María Pilar de; Stoll, Hermann; Civalleri, Bartolomeo; Causà, Mauro; Voloshina, Elena; Mitrushchenkov, Alexander O.; Pi, Martí

    2014-10-21

    In this work we propose a general strategy to calculate accurate He–surface interaction potentials. It extends the dispersionless density functional approach recently developed by Pernal et al. [Phys. Rev. Lett. 103, 263201 (2009)] to adsorbate-surface interactions by including periodic boundary conditions. We also introduce a scheme to parametrize the dispersion interaction by calculating two- and three-body dispersion terms at coupled cluster singles and doubles and perturbative triples (CCSD(T)) level via the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)]. The performance of the composite approach is tested on {sup 4}He/graphene by determining the energies of the low-lying selective adsorption states, finding an excellent agreement with the best available theoretical data. Second, the capability of the approach to describe dispersionless correlation effects realistically is used to extract dispersion effects in time-dependent density functional simulations on the collision of {sup 4}He droplets with a single graphene sheet. It is found that dispersion effects play a key role in the fast spreading of the {sup 4}He nanodroplet, the evaporation-like process of helium atoms, and the formation of solid-like helium structures. These characteristics are expected to be quite general and highly relevant to explain experimental measurements with the newly developed helium droplet mediated deposition technique.

  3. Theoretical estimates of the critical exponents of the superfluid transition in {sup 4}He by lattice methods

    SciTech Connect

    Campostrini, Massimo; Hasenbusch, Martin; Vicari, Ettore; Pelissetto, Andrea

    2006-10-01

    We improve the theoretical estimates of the critical exponents for the three-dimensional XY universality class that apply to the superfluid transition in {sup 4}He along the {lambda} line of its phase diagram. We obtain the estimates {alpha}=-0.0151(3), {nu}=0.6717(1), {eta}=0.0381(2), {gamma}=1.3178(2), {beta}=0.3486(1), and {delta}=4.780(1). Our results are obtained by finite-size scaling analyses of high-statistics Monte Carlo simulations up to lattice size L=128 and resummations of 22nd-order high-temperature expansions of two improved models with suppressed leading scaling corrections. We note that our result for the specific-heat exponent {alpha} disagrees with the most recent experimental estimate {alpha}=-0.0127(3) at the superfluid transition of {sup 4}He in a microgravity environment.

  4. Are high 3He/4He ratios in oceanic basalts an indicator of deep-mantle plume components?

    USGS Publications Warehouse

    Meibom, A.; Anderson, D.L.; Sleep, N.H.; Frei, R.; Chamberlain, C.P.; Hren, M.T.; Wooden, J.L.

    2003-01-01

    The existence of a primordial, undegassed lower mantle reservoir characterized by high concentration of 3He and high 3He/4He ratios is a cornerstone assumption in modern geochemistry. It has become standard practice to interpret high 3He/4He ratios in oceanic basalts as a signature of deep-rooted plumes. The unfiltered He isotope data set for oceanic spreading centers displays a wide, nearly Gaussian, distribution qualitatively similar to the Os isotope (187Os/188 Os) distribution of mantle-derived Os-rich alloys. We propose that both distributions are produced by shallow mantle processes involving mixing between different proportions of recycled, variably aged radiogenic and unradiogenic domains under varying degrees of partial melting. In the case of the Re-Os isotopic system, radiogenic mid-ocean ridge basalt (MORB)-rich and unradiogenic (depleted mantle residue) endmembers are constantly produced during partial melting events. In the case of the (U+Th)-He isotope system, effective capture of He-rich bubbles during growth of phenocryst olivine in crystallizing magma chambers provides one mechanism for 'freezing in' unradiogenic (i.e. high 3He/4He) He isotope ratios, while the higher than chondritic (U+Th)/He elemental ratio in the evolving and partially degassed MORB melt provides the radiogenic (i.e. low 3He/4He) endmember. If this scenario is correct, the use of He isotopic signatures as a fingerprint of plume components in oceanic basalts is not justified. Published by Elsevier Science B.V.

  5. Production of {sup 4}He, {sup 3}He, and tritium from Be irradiated in FFTF-MOTA-2B

    SciTech Connect

    Greenwood, L.R.

    1998-03-01

    The production of {sup 4}He, {sup 3}He, and tritium has been calculated for beryllium irradiated in the Materials Open Test Assembly (MOTA)-2B experiment in the Fast Flux Test Facility (FFTF). Reaction rates were based on adjusted neutron spectra determined from reactor dosimetry measurements at seven different elevations in the irradiation assembly. Equations are given so that gas production, dpa, and neutron fluences can be calculated for any specific elevation in the MOTA-2B assembly.

  6. Motion of a helical vortex filament in superfluid 4He under the extrinsic form of the local induction approximation

    NASA Astrophysics Data System (ADS)

    Van Gorder, Robert A.

    2013-08-01

    Very recently, Shivamoggi ["Vortex motion in superfluid 4He: Reformulation in the extrinsic vortex-filament coordinate space," Phys. Rev. B 84, 012506 (2011)], 10.1103/PhysRevB.84.012506 studied the extrinsic form of the local induction approximation (LIA) for the motion of a Kelvin wave on a vortex filament in superfluid 4He, and obtained some results in a cubic approximation. Presently, we study the motion of helical vortex filaments in superfluid 4He under the exact fully nonlinear LIA considered in potential form by Van Gorder ["Fully nonlinear local induction equation describing the motion of a vortex filament in superfluid 4He," J. Fluid Mech. 707, 585 (2012)], 10.1017/jfm.2012.308 and obtained from the Biot-Savart law through the equations of Hall and Vinen ["The rotation of liquid helium II. I. Experiments on the propagation of second sound in uniformly rotating helium II," Proc. R. Soc. London, Ser. A 238, 204 (1956)], 10.1098/rspa.1956.0214 including superfluid friction terms. Nonlinear dispersion relations governing the helical Kelvin wave on such a vortex filament are derived in exact form, from which we may exactly calculate the phase and group velocity of the Kelvin wave. With this, we classify the motion of a helical Kelvin wave on a vortex filament under the LIA. The dispersion relations and results, which follow are exact in nature, in contrast to most results in the literature, which are usually numerical approximations. As such, our results accurately capture the qualitative behavior of the Kelvin waves under the LIA. Extensions to other frameworks are discussed.

  7. The structure of mixed {sup 3}He-{sup 4}He droplets doped with OCS: A density functional approach

    SciTech Connect

    Leal, Antonio; Mateo, David; Pi, Martí; Barranco, Manuel; Navarro, Jesús

    2013-11-07

    We have investigated the structure and energetics of mixed {sup 3}He-{sup 4}He droplets doped with a carbonyl sulfide molecule within a density functional approach considering a small but finite temperature of 0.1 K. The molecule is treated as an external field to which the helium droplet is attached. The energetics and appearance of these droplets are discussed for selected numbers of helium atoms, identifying the first magic numbers of the fermionic component.

  8. Photodisintegration cross section of the reaction (4)He(γ,p)(3)H between 22 and 30 MeV.

    PubMed

    Raut, R; Tornow, W; Ahmed, M W; Crowell, A S; Kelley, J H; Rusev, G; Stave, S C; Tonchev, A P

    2012-01-27

    The two-body photodisintegration cross section of (4)He into a proton and triton was measured with monoenergetic photon beams in 0.5 MeV energy steps between 22 and 30 MeV. High-pressure (4)He-Xe gas scintillators of various (4)He/Xe ratios served as targets and detectors. Pure Xe gas scintillators were used for background studies. A NaI detector together with a plastic scintillator paddle was employed for determining the incident photon flux. Our comprehensive data set follows the trend of the theoretical calculations of the Trento group very well, although our data are consistently lower in magnitude by about 5%. However, they differ significantly from the majority of the previous data, especially from the recent data of Shima et al. The latter data had put into question the validity of theoretical approaches used to calculate core-collapse supernova explosions and big-bang nucleosynthesis abundances of certain light nuclei. PMID:22400829

  9. Static and thermodynamic properties of low-density supercritical 4He-breakdown of the Feynman-Hibbs approximation.

    PubMed

    Kowalczyk, Piotr; Brualla, Lorenzo; Gauden, Piotr A; Terzyk, Artur P

    2009-10-28

    We study the applicability of the semiclassical Feynman and Hibbs (FH) (second-order or fourth-order) effective potentials to the description of the thermodynamic properties of quantum fluids at finite temperatures. First, we use path integral Monte Carlo (PIMC) simulations to estimate the thermodynamic/static properties of our model quantum fluid, i.e. low-density 4He at 10 K. With PIMC we obtain the experimental equation of state, the single-particle mean kinetic energy, the single-particle density matrix and the single-particle momentum distribution of this system at low densities. We show that our PIMC results are in full agreement with experimental data obtained with deep inelastic neutron scattering at high momentum transfers (D. Colognesi, C. Andreani, R. Senesi, Europhys. Lett., 2000, 50, 202). As expected, in this region of the 4He phase diagram, quantum effects modify the width of the single-particle momentum distribution but do not alter its Gaussian shape. Knowing the exact values of density, pressure and single-particle mean kinetic energy for our model quantum fluid, we investigate the limitations of the semiclassical FH effective potentials. We show that commonly used 'short-time' approximations to the high-temperature density matrix due to Feynman and Hibbs can only be applied in a very limited range of the 4He phase diagram. We found that FH effective potentials reproduce the experimental densities of 4He at 10 K for Lambda/a < 0.45 (Lambda = 2.73 A denotes the thermal de Broglie wavelength, a = rho(-1/3) is the mean nearest-neighbor distance in the fluid and rho denotes fluid density). Moreover, semiclassical FH effective potentials are able to correctly predict the single-particle mean kinetic energy of 4He at 10 K in a very limited range of fluid densities, i.e.Lambda/a < 0.17. We show that the ad hoc application of the semiclassical FH effective potentials for the calculation of the thermodynamic properties of dense liquid-like para

  10. Direct measurement of the 4He (12C, 16O) γ reaction cross section near stellar energies

    NASA Astrophysics Data System (ADS)

    Sagara, Kenshi

    2014-09-01

    The 12C+4He-->16O + γ reaction is one of the key reactions in stellar He-burning, but its total cross section at stellar energy (Ecm = 0.3 MeV) has not been measured yet, in spite of many experiments made in the world for about a half century. At Kyushu University Tandem accelerator Laboratory (KUTL), we have been making direct measurement of the 4He (12C, 16O) γ total cross section below Ecm = 2.4 MeV for about 20 years. We have measured the total cross section at Ecm = 2.4, 1.5 and 1.2 MeV. Now we are preparing to measure the cross section at 1.0 MeV. The direct measurement was made from Ecm = 5 MeV down to 1.9 MeV at Ruhr University, Bochum. We use a pulsed 12C beam and a windowless 4He target, and detect all the 16O recoils in a charge state. A usually continuum 12C beam from our tandem accelerator is pulsed by a pre-buncher, a main buncher, and a beam chopper. Our tandem accelerator was designed to be used at the acceleration voltage of 6-10 MV. For the 4He (12C, 16O) γ experiment we need to use it at 1.3-1.8 MV where beam transmission is very low, then we have invented an acceleration-deceleration method for the tandem accelerator. We have developed a blow-in windowless He target based on an original idea. To separate 16O recoils from the 12C beam, we developed a recoil-mass separator. To reject 12C backgrounds, we developed a long-time chopper, and an ionization chamber. Now, we are preparing to measure time-of-flight of 16O recoils and 12C backgrounds. Many original instruments and the experimental results will be presented. Finally we discuss what are necessary for future direct measurement of the 4He (12C, 16O) γ total cross section below 1.0 MeV, down to 0.7 MeV. A dynamitron accelerator and hard-working researchers may be inevitable. The 12C+4He-->16O + γ reaction is one of the key reactions in stellar He-burning, but its total cross section at stellar energy (Ecm = 0.3 MeV) has not been measured yet, in spite of many experiments made in the world

  11. High pressure line shapes of the Rb D1 and D2 lines for 4He and 3He collisions

    NASA Astrophysics Data System (ADS)

    Miller, Wooddy S.; Rice, Christopher A.; Hager, Gordon D.; Rotondaro, Mathew D.; Berriche, Hamid; Perram, Glen P.

    2016-11-01

    Line shapes for the Rb D1 (51/2 2S ↔ 51/2 2P) and D2 (51/2 2S ↔ 53/2 2P) transitions with 4He and 3He collisions at pressures of 500-15,000 Torr and temperatures of 333-533 K have been experimentally observed and compared to predictions from the Anderson-Talman theory. The ground X1/2 + 2Σ and excited A1/2 + 2Π, A3/2 2Π, and B1/2 + 2Σ potential energy surfaces required for the line shape predictions have been calculated using a one-electron pseudo-potential technique. The observed collision induced shift rates for 4He are dramatically higher for the D1 line, 4.60±0.12 MHz/Torr, than the D2 line, 0.20±0.14 MHz/Torr. The asymmetry is somewhat larger for the D1 line and has the same sign as the shifting rate. The 3He broadening rate for the D2 line is 4% larger than the 4He rate, and 14% higher for the D1 line, reflecting the higher relative speed. The calculated broadening rates are systematically larger than the observed rates by 1.1-3.2 MHz/Torr and agree within 14%. The primary focus of the current work is to characterize the high pressure line shapes, focusing on the non-Lorentzian features far from line center. In the far wing, the cross-section decreases by more than 4 orders of magnitude, with a broad, secondary maximum in the D2 line near 735 nm. The potentials do not require empirical modification to provide excellent quantitative agreement with the observations. The dipole moment variation and absorption Boltzmann factor is critical to obtaining strong agreement in the wings.

  12. Analysis of the scintillation mechanism in a pressurized {sup 4}He fast neutron detector using pulse shape fitting

    SciTech Connect

    Kelley, R.P. Ray, H.; Jordan, K.A.; Murer, D.

    2015-03-15

    An empirical investigation of the scintillation mechanism in a pressurized {sup 4}He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a {sup 252}Cf spontaneous fission source and a (d,d) neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the {sup 4}He detector. A further understanding of this mechanism in the {sup 4}He detector will advance the use of this system as a neutron spectrometer. For {sup 252}Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d) generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a {sup 252}Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies.

  13. Astrophysical S factor for the 4He(3He,γ)7Be reaction at medium energies

    NASA Astrophysics Data System (ADS)

    Carmona-Gallardo, M.; Nara Singh, B. S.; Tengblad, O.; Hass, M.; Alcorta, M.; Borge, M. J. G.; Briz, J. A.; Cruz, C.; Cubero, M.; Domínguez-Reyes, R.; Fulton, B. R.; Fynbo, H.; Gordillo, N.; Haquin, G.; Nir-El, Y.; Kumar, V.; Maira, A.; McGrath, J.; Muñoz-Martín, A.; Perea, A.; Yungreis, Z.

    2012-02-01

    The astrophysical S factor for the 4He(3He,γ)7Be direct capture reaction plays a major role in the context of solar neutrino flux and primordial 7Li abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of ECM = 900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor.

  14. A precise extraction of the induced polarization in the 4He(e,e'p)3H reaction

    SciTech Connect

    S.P. Malace, M. Paolone, S. Strauch

    2011-01-01

    We measured with unprecedented precision the induced polarization Py in 4He(e,e'p)3H at Q^2 = 0.8 (GeV/c)^2 and 1.3 (GeV/c)^2. The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are over-estimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin independent charge-exchange term in the latter calculation.

  15. Analysis of states in {sup 13}C populated in {sup 9}Be + {sup 4}He resonant scattering

    SciTech Connect

    Freer, M.; Ashwood, N. I.; Curtis, N.; Kokalova, Tz.; Wheldon, C.; Di Pietro, A.; Figuera, P.; Fisichella, M.; Scuderi, V.; Torresi, D.; Grassi, L.; Jelavic Malenica, D.; Koncul, M.; Mijatovic, T.; Prepolec, L.; Skukan, N.; Soic, N.; Szilner, S.; Tokic, V.; Milin, M.

    2011-09-15

    Measurements of {sup 9}Be + {alpha} resonant scattering have been performed using the thick-target approach with a {sup 4}He gas volume and a large-area silicon strip detector. {sup 9}Be beam energies in the range 12 to 21.4 MeV were used to measure the {sup 13}C excitation energy spectrum between 13.2 and 16.2 MeV. An R-matrix analysis has been performed to characterize the spins and widths of {sup 13}C resonances, some of which have been proposed to be associated with a 3{alpha}+n molecular band.

  16. Relationship between 3He/4He ratios and subduction of the Philippine Sea plate beneath southwest Japan

    NASA Astrophysics Data System (ADS)

    Umeda, Koji; Kusano, Tomohiro; Asamori, Koichi; McCrank, Glen F.

    2012-10-01

    Regional and local variations in mantle helium provide insight into the coupling of mantle-crust tectonics, and heat and/or mass transfer from the Earth's interior. In order to further elucidate the geographic distribution of3He/4He ratios in southwest Japan, the data from a total of 924 sites were compiled and synthesized. These include data from 48 additional hot spring and drinking water well sites on the northern Kyushu Island and in the northern Chugoku region. There appears to be good correlation between variations in helium isotope ratios and the geophysical evidence used to determine the configuration of the subducting Philippine Sea plate (PHS). Seismological studies reveal that the leading edge of the aseismic slab does not extend to the northern Chugoku region nor to the Osaka Bay area, where gas samples with significantly elevated 3He/4He ratios occur. This is consistent with a mantle-derived helium in these areas, from melts and/or mantle fluids ascribed to upwelling asthenosphere without being hindered by the descending PHS slab. In contrast, gas samples in the regions where the overriding crust comes into direct contact with the subducting PHS are dominated by radiogenic helium derived from the crust because of the absence of a mantle wedge, the most plausible source of mantle helium. Owing to the abrupt changes in the seismicity and focal mechanisms of intraplate earthquakes, the PHS is considered to have slab tears beneath the Kii Channel and/or the eastern Kii Peninsula oriented in a NW-SE direction. However, the lenear alignment of anomalously high3He/4He ratios does not appear to be NW-SE trending along the assumed slab tears but rather forms an broad, ENE-WSW trending zone between the tears where low-frequency events occur. The emanation of gas with elevated3He/4He ratios in the central peninsula can be explained by the upward mobilization of mantle volatiles derived from the mantle wedge above the PHS and/or transferred from the hydrated slab

  17. Unified description of 6Li structure and deuterium-4He dynamics with chiral two- and three-nucleon forces

    DOE PAGESBeta

    Hupin, Guillaume; Quaglioni, Sofia; Navratil, Petr

    2015-05-29

    Here, we provide a unified ab initio description of the 6Li ground state and elastic scattering of deuterium (d) on 4He (α) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of 6Li. The calculation reproduces the empirical binding energy of 6Li, yielding an asymptotic D- to S-state ratio of the 6Li wave function in the d+α configuration of –0.027, in agreement with a determination from 6Li–4He elastic scattering, but overestimates the excitation energy of the 3+more » state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the 2H(α,γ)6Li radiative capture, responsible for the big-bang nucleosynthesis of 6Li.« less

  18. Unified description of ^{6}Li structure and deuterium-^{4}He dynamics with chiral two- and three-nucleon forces.

    PubMed

    Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr

    2015-05-29

    We provide a unified ab initio description of the ^{6}Li ground state and elastic scattering of deuterium (d) on ^{4}He (α) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of ^{6}Li. The calculation reproduces the empirical binding energy of ^{6}Li, yielding an asymptotic D- to S-state ratio of the ^{6}Li wave function in the d+α configuration of -0.027, in agreement with a determination from ^{6}Li-^{4}He elastic scattering, but overestimates the excitation energy of the 3^{+} state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the ^{2}H(α,γ)^{6}Li radiative capture, responsible for the big-bang nucleosynthesis of ^{6}Li.

  19. Frequency-dependent Study of Ultrapure Solid 4He by Using Rigid Double-pendulum Torsional Oscillator

    NASA Astrophysics Data System (ADS)

    Choi, Jaewon; Shin, Jaeho; Kim, Eunseong

    2015-03-01

    The physical origin of the period drop found in the torsional oscillator (TO) containing solid 4He was previously interpreted as the appearance of supersolidity. The current consensus is that the increase in the shear modulus leads to the period anomaly. Further studies show that the stiffening effect in TO can be amplified if a TO is not properly designed to be ``rigid.'' In this study, we designed a rigid double-pendulum TO. High purity solid 4He sample (0.6ppb) was grown by the block capillary method. The resonant period of TO starts to decrease from the empty cell data at 80mK. The ratio of the resonant period changes to the total mass loading are 3 . 8 ×10-5 and 2 . 6 ×10-4 for 1st and 2nd mode, respectively. Unlike recent experiment, we could not found a frequency-independent period drop. The upper bound for the putative supersolid fraction is less than 4 ×10-6 . The dissipation peak accompanied with the period drop was also analyzed with Cole-Cole plot and ωτ plot. We conclude that major contribution for the anomalous TO responses comes from the elastic effect.

  20. Unified description of ^{6}Li structure and deuterium-^{4}He dynamics with chiral two- and three-nucleon forces.

    PubMed

    Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr

    2015-05-29

    We provide a unified ab initio description of the ^{6}Li ground state and elastic scattering of deuterium (d) on ^{4}He (α) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of ^{6}Li. The calculation reproduces the empirical binding energy of ^{6}Li, yielding an asymptotic D- to S-state ratio of the ^{6}Li wave function in the d+α configuration of -0.027, in agreement with a determination from ^{6}Li-^{4}He elastic scattering, but overestimates the excitation energy of the 3^{+} state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the ^{2}H(α,γ)^{6}Li radiative capture, responsible for the big-bang nucleosynthesis of ^{6}Li. PMID:26066431

  1. Studies of kinetic processes in a concentrated 3He-4He solution using an oscillating tuning fork

    NASA Astrophysics Data System (ADS)

    Bakhvalova, V. A.; Gritsenko, I. A.; Rudavskii, E. Ya.; Chagovets, V. K.; Sheshin, G. A.

    2015-07-01

    The dissipative processes causing the damping of quartz tuning fork vibrations in a solution of 15% 3He in 4He, are studied in a temperature range of 0.5-2.3 K. The resonance curves of the tuning forks are measured in the laminar flow region of the liquid, and their width is determined by the width of the dissipative processes. We examined tuning forks with a resonance frequency of 32 kHz, located inside a flask ("enclosed") and tuning forks without a flask ("unenclosed"). The results of the experiment are compared to existing theories. It was found that a significant contribution to the damping of tuning fork oscillations for a solution, as opposed to pure 4He, is from the second sound radiation, the contribution of which exceeds the input of viscous dissipation at low temperatures. The radiation of the first sound does not contribute to the damping of the oscillations of the "enclosed" fork due to the small size of the cell versus the wavelength. In the case of the "unenclosed" fork, the damping is determined by three processes: viscous dissipation and radiation of the first and second sounds.

  2. Low-3He/4He sublithospheric mantle source for the most magnesian magmas of the Karoo large igneous province

    NASA Astrophysics Data System (ADS)

    Heinonen, Jussi S.; Kurz, Mark D.

    2015-09-01

    The massive outpourings of Karoo and Ferrar continental flood basalts (CFBs) ∼180 Ma ago mark the initial Jurassic rifting stages of the Gondwana supercontinent. The origin and sources of these eruptions have been debated for decades, largely due to difficulties in defining their parental melt and mantle source characteristics. Recent findings of Fe- and Mg-rich dikes (depleted ferropicrite suite) from Vestfjella, western Dronning Maud Land, Antarctica, have shed light on the composition of the deep sub-Gondwanan mantle: these magmas have been connected to upper mantle sources presently sampled by the Southwest Indian Ocean mid-ocean ridge basalts (SWIR MORBs) or to high 3He/4He plume-entrained non-chondritic primitive mantle sources formed early in Earth's history. In an attempt to determine their He isotopic composition and relative contributions from magmatic, cosmogenic, and radiogenic He sources, we performed in-vacuo stepwise crushing and melting analyses of olivine mineral separates, some of which were abraded to remove the outer layer of the grains. The best estimate for the mantle isotopic composition is given by a sample with the highest amount of He released (>50%) during the first crushing step of an abraded coarse fraction. It has a 3He/4He of 7.03 ± 0.23 (2σ) times the atmospheric ratio (Ra), which is indistinguishable from those measured from SWIR MORBs (6.3-7.3 Ra; source 3He/4He ∼6.4-7.6 Ra at 180 Ma) and notably lower than in the most primitive lavas from the North Atlantic Igneous Province (up to 50 Ra), considered to represent the epitome magmas from non-chondritic primitive mantle sources. Previously published trace element and isotopic (Sr, Nd, and Pb) compositions do not suggest a direct genetic link to any modern hotspot of Indian or southern Atlantic Oceans. Although influence of a mantle plume cannot be ruled out, the high magma temperatures and SWIR MORB-like geochemistry of the suite are best explained by supercontinent insulation

  3. Parity-Violating Electron Scattering from {sup 4}He and the Strange Electric Form Factor of the Nucleon

    SciTech Connect

    Aniol, Konrad; Armstrong, David; Averett, Todd; Benaoum, Hachemi; Bertin, Pierre; Burtin, Etienne; Cahoon, Jason; Cates, Gordon; Chang, C; Chao, Yu-Chiu; Chen, Jian-Ping; Choi, Seonho; Chudakov, Eugene; Craver, Brandon; Cusanno, Francesco; Decowski, Piotr; Deepa, Deepa; Ferdi, Catherine; Feuerbach, Robert; Finn, John; Frullani, Salvatore; Fuoti, Kirsten; Garibaldi, Franco; Gilman, Ronald; Glamazdin, Oleksandr; Gorbenko, V; Grames, Joseph; Hansknecht, John; Higinbotham, Douglas; Holmes, Richard; Holmstrom, Timothy; Humensky, Thomas; Ibrahim, Hassan; Jager, Cornelis De; Jiang, Xiaodong; Kaufman, Lisa; Kelleher, Aidan; Kolarkar, Ameya; Kowalski, Stanley; Kumar, Krishna; Lambert, Daniel; Laviolette, Peter; LeRose, John; Lhuillier, David; Liyanage, Nilanga; Margaziotis, Demetrius; Mazouz, Malek; McCormick, Kathy; Meekins, David; Meziani, Zein-Eddine; Michaels, Robert; Moffit, Bryan; Monaghan, Peter; Camacho, Carlos Munoz; Nanda, Sirish; Nelyubin, Vladimir; Neyret, Damien; Paschke, Kent; Poelker, Benard; Pomatsalyuk, Roman; Qiang, Yi; Reitz, Bodo; Roche, Julie; Saha, Arunava; Singh, Jaideep; Snyder, Ryan; Souder, Paul; Subedi, Ramesh; Suleiman, Riad; Sulkosky, Vincent; Tobias, William; Urciuoli, Guido; Vacheret, Antonin; Voutier, Eric; Wang, Kebin; Wilson, R; Wojtsekhowski, Bogdan; Zheng, Xiaochao

    2005-06-01

    We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from {sup 4}He at an average scattering angle {theta}{sub lab} = 5.7 degrees and a four-momentum transfer Q{sup 2} = 0.091 GeV{sup 2}. From these data, for the first time, the strange electric form factor of the nucleon G{sub E}{sup s} can be isolated. The measured asymmetry of A{sub PV} = 6.72 {+-} 0.84 (stat) {+-} 0.21 (syst) parts per million yields a value of G{sub E}{sup s} = -0.038 {+-} 0.042 (stat) {+-} 0.010 (syst), consistent with zero.

  4. Capacitance-voltage studies of InP metal-oxide-semiconductor devices irradiated with 4He + ions

    NASA Astrophysics Data System (ADS)

    Tin, C. C.; Barnes, P. A.; Williams, J. R.; Patuwathavithane, C. S.; Van Staagen, P. K.

    1989-11-01

    Capacitance-voltage (C-V) measurements have been made on n-InP metal-oxide-semiconductor (MOS) devices damaged by 2-MeV 4 He+ ion bombardment. The C-V curves for samples with thin oxide layer (˜100 Å) show the presence of a depletion layer during both forward and reverse bias. This behavior is significantly different from those of normal, undamaged MOS devices. Measurements made on n-InP MOS samples with different oxide thicknesses show that the C-V curves gradually approach that of a MOS device on a p-type substrate. The anomalous behavior of the C-V curves for the irradiated samples can be explained by the presence of an n-p-n structure under the oxide layer.

  5. Acceptance Studies for 4He(e,e'p)X Reaction up to High Missing Energies and Momenta

    NASA Astrophysics Data System (ADS)

    Finton, Drew; Benmokhtar, Fatiha

    2014-03-01

    Data collected from the Helium-4 target in Hall A at Thomas Jefferson National Accelerator Facility (TJNAF) in Newport News, Virginia, was analyzed using the object-oriented data analysis software ROOT and used to create Missing Energy Spectra for Missing Momenta ranging from 150 MeV/c to 755 MeV/c for 4He(e,e'p)X reaction channels. Jefferson Lab is a continuous electron beam accelerator facility, and Hall A contains two high resolution spectrometers as well as the cryogenic Helium-4 target. Acceptance cuts were made to six measured variables to remove background noise, and then applied to produce a Missing Energy Spectrum showing two- and three-body break up channels as well as pion electro-production energy threshold. The analysis of these missing energy spectra will be used to understand the contributions of one-, two-, and three-body interactions.

  6. A Survey of Beam Asymmetries in Semi-exclusive Electron Scattering on {sup 4}He and {sup 12}C

    SciTech Connect

    Dan Protopopescu

    2002-12-01

    A study of the polarized electron beam asymmetry in semi-exclusive (e,e{prime}p) reactions on {sup 4}He and {sup 12}C over a large kinematic range has been performed. The beam asymmetry A{prime}{sub LT} is related to the imaginary part of the longitudinal-transverse interference and therefore it vanishes in reactions proceeding through a channel with a single dominant mechanism. In quasifree nucleon knockout, the helicity asymmetry provides an unambiguous signature for the interference between direct knockout and rescattering amplitudes. The data were taken in April-May 1999 using polarized beams of energies between 2.2 and 4.4 GeV, with the CEBAF Large Acceptance Spectrometer (CLAS) detector located in Hall B at the Jefferson Laboratory, VA. The measured asymmetries compare well with the theoretical predictions.

  7. Electric breakdown and ionization detection in normal liquid and superfluid 4He for the SNA nEDM experiment

    NASA Astrophysics Data System (ADS)

    Karcz, Maciej

    A new experiment to search for the neutron electric dipole moment (nEDM) is under construction at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The SNS nEDM experiment is a national collaboration spanning over 20 universities and laboratories with more than 100 physicists and engineers contributing to the research and development. The search for a nEDM is a precision test of time reversal symmetry in particle physics, in the absence of a discovery, the SNS nEDM experiment seeks to improve the present limit on the nEDM value by two orders of magnitude. A non-zero value of the nEDM would help to explain the asym- metry between matter and anti-matter in the universe by providing an additional source of charge conjugation and parity symmetry violation, a necessary ingredient in the theory of baryogenesis in the early universe. The nEDM experiment will measure the Larmor precession frequency of neutrons by detecting scintillation from neutron capture by a dilute concentration of 3He inside a bath of superfluid 4He. Neutron capture by 3He is spin-dependent and the magnetic moments of the neutron and the 3He nucleus are comparable. A direct measurement of the precession frequency of polarized 3He and scintillation from neutron capture allows for the relative precession frequencies of 3He and the neutron to be determined. The experiment will then look for changes in the relative precession of 3He and neutrons under the influence of strong electric fields. 3He has negligible EDM and therefore any deviation due to an applied electric field would be from a nEDM. The nEDM experiment will need to apply strong electric fields inside superfluid (SF) 4He and it was necessary to investigate the ability of SF 4He to sustain electric fields. An experiment to study electric breakdown in superfluid 4He was constructed at the Indiana University Center for Exploration of Energy and Matter (CEEM). The experiment studied the electric breakdown behavior of liquid

  8. Frequency-dependent study of solid 4He contained in a rigid double-torus torsional oscillator

    NASA Astrophysics Data System (ADS)

    Choi, Jaewon; Shin, Jaeho; Kim, Eunseong

    2015-10-01

    The rigid double-torus torsional oscillator (TO) is constructed to reduce any elastic effects inherent to complicated TO structures, allowing explicit probing for a genuine supersolid signature. We investigated the frequency- and temperature-dependent response of the rigid double-torus TO containing solid 4He with 0.6-ppb 3He and 300-ppb 3He . We did not find evidence to support the frequency-independent contribution proposed to be a property of supersolid helium. The frequency-dependent contribution which comes from the simple elastic effect of solid helium coupled to the TO is essentially responsible for the entire response. The magnitude of the period drop is linearly proportional to f2, indicating that the responses observed in this TO are mostly caused by the overshoot of "soft" solid helium against the wall of the torus. Dissipation of the rigid TO is vastly suppressed compared to that of nonrigid TOs.

  9. Frequency stabilization of a 1083 nm fiber laser to {sup 4}He transition lines with optical heterodyne saturation spectroscopies

    SciTech Connect

    Gong, W.; Peng, X. Li, W.; Guo, H.

    2014-07-15

    Two kinds of optical heterodyne saturation spectroscopies, namely, frequency modulation spectroscopy (FMS) and modulation transfer spectroscopy (MTS), are demonstrated for locking a fiber laser to the transition lines of metastable {sup 4}He atoms around 1083 nm. The servo-loop error signals of FMS and MTS for stabilizing laser frequency are optimized by studying the dependence of the peak-to-peak amplitude and slope on the optical power of pump and probe beams. A comparison of the stabilization performances of FMS/MTS and polarization spectroscopy (PS) is presented, which shows that MTS exhibits relatively superior performance with the least laser frequency fluctuation due to its flat-background dispersive signal, originated from the four-wave mixing process. The Allan deviation of the stabilized laser frequency is 5.4 × 10{sup −12}@100 s with MTS for data acquired in 1000 s, which is sufficiently applicable for fields like laser cooling, optical pumping, and optical magnetometry.

  10. Frequency stabilization of a 1083 nm fiber laser to 4He transition lines with optical heterodyne saturation spectroscopies

    NASA Astrophysics Data System (ADS)

    Gong, W.; Peng, X.; Li, W.; Guo, H.

    2014-07-01

    Two kinds of optical heterodyne saturation spectroscopies, namely, frequency modulation spectroscopy (FMS) and modulation transfer spectroscopy (MTS), are demonstrated for locking a fiber laser to the transition lines of metastable 4He atoms around 1083 nm. The servo-loop error signals of FMS and MTS for stabilizing laser frequency are optimized by studying the dependence of the peak-to-peak amplitude and slope on the optical power of pump and probe beams. A comparison of the stabilization performances of FMS/MTS and polarization spectroscopy (PS) is presented, which shows that MTS exhibits relatively superior performance with the least laser frequency fluctuation due to its flat-background dispersive signal, originated from the four-wave mixing process. The Allan deviation of the stabilized laser frequency is 5.4 × 10-12@100 s with MTS for data acquired in 1000 s, which is sufficiently applicable for fields like laser cooling, optical pumping, and optical magnetometry.

  11. Ratios of 15N/12C and 4He/12C inclusive electroproduction cross sections in the nucleon resonance region

    SciTech Connect

    Peter Bosted; Robert Fersch

    2007-12-14

    The ratio of inclusive electron scattering cross sections for 15N/12C was determined in the kinematic range 0.8<2 GeV and 0.2<1 GeV2 using 2.285 GeV electrons and the CLAS detector at Jefferson Lab. The ratio exhibits only slight resonance structure, as predicted by a phenomenological model, and also by quark-hadron duality. Within the super-scaling quasi-elastic model, slight evidence is found for a 1 MeV lower effective nucleon binding energy in 15N than in 12C. Ratios of 4He/12C using 1.6 to 2.5 GeV electrons are in good agreement with the phenomenological model.

  12. Parity-Violating Electron Scattering from {sup 4}He and the Strange Electric Form Factor of the Nucleon

    SciTech Connect

    Aniol, K.A.; Margaziotis, D.J.; Armstrong, D.S.; Averett, T.; Finn, J.M.; Holmstrom, T.; Kelleher, A.; Moffit, B.; Sulkosky, V.; Benaoum, H.; Holmes, R.; Souder, P.A.; Bertin, P.Y.; Ferdi, C.

    2006-01-20

    We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from {sup 4}He at an average scattering angle <{theta}{sub lab}>=5.7 deg. and a four-momentum transfer Q{sup 2}=0.091 GeV{sup 2}. From these data, for the first time, the strange electric form factor of the nucleon G{sub E}{sup s} can be isolated. The measured asymmetry of A{sub PV}=(6.72{+-}0.84{sub (stat)}{+-}0.21{sub (syst)})x10{sup -6} yields a value of G{sub E}{sup s}=-0.038{+-}0.042{sub (stat)}{+-}0.010{sub (syst)}, consistent with zero.

  13. Polarization Transfer in {sup 4}He(e-vector,e{sup '}p-vector){sup 3}H

    SciTech Connect

    Paolone, Michael

    2007-10-26

    Polarization transfer in quasi-elastic nucleon knockout is sensitive to the properties of the nucleon in the nuclear medium, including possible modification of the nucleon form factor and/or spinor. In our recently completed experiment E03-104 at Jefferson Lab we measured the proton recoil polarization in the {sup 4}He(e-vector,e{sup '}p-vector){sup 3}H reaction at a Q{sup 2} of 0.8 (GeV/c){sup 2} and 1.3 (GeV/c){sup 2} with unprecedented precision. These data complement earlier data between 0.4 and 2.6 (GeV/c){sup 2} from both Mainz and Jefferson Lab, in which the measured ratio of polarization-transfer coefficients differs from a fully relativistic DWIA calculation. Preliminary results hint at a possible unexpected Q{sup 2} dependence in the polarization transfer coefficient ratio. Final analysis will help constrain FSI models.

  14. Nonlinear Transport of the Wigner Crystal on Superfluid 4He in a Quasi-One-Dimensional Channel

    NASA Astrophysics Data System (ADS)

    Vasylenko, Anna A.; Misko, Vyacheslav R.

    2014-07-01

    We study transport properties of a Wigner crystal driven by an external force on the surface of superfluid 4He, in the "quantum wire" regime, i.e. in the quasi-one-dimensional (quasi-1D) case when a typical width of the channel is comparable to the inter-electron separation. Utilizing molecular dynamics simulations, we investigate the electronic transport through the channels with different constrictions: (i) geometrical constrictions with varying shape and size, and (ii) a saddle-point potential with varying gate voltage. The average particle velocity has been calculated as a function of the driving force or gate voltage. We have revealed a significant difference in the dynamical behavior for long and short constrictions. In particular, we found that the oscillations of the average particle velocity in channels with short constrictions exhibit a clear correlation with the transitions between the states with different numbers of rows of particles in the constriction, while for channels with longer constrictions these oscillations are suppressed. The obtained results are in agreement with the recent experimental observations,1 and thus bring new important insights into the dynamics of electrons floating on the surface of superfluid 4He in channels with constrictions. Special Issue Comments: This article presents results on the dynamics of electrons moving on the surface of liquid helium in narrow channels with constrictions, with a focus on the "quantum wire", i.e. single file, regime. This article is connected to the Special Issue articles about advanced statistical properties in single file dynamics39 and the experiments on liquid helium.40

  15. Correlation of gold in siliceous sinters with 3He 4He in hot spring waters of Yellowstone National Park

    USGS Publications Warehouse

    Fournier, R.O.; Kennedy, B.M.; Aoki, M.; Thompson, J.M.

    1994-01-01

    temperatures may contain waters with different [H2S] and [Au]. The [H2S] in a subsurface reservoir water is difficult to assess on the basis of analyses of hot spring waters because of uncertainties about steam loss during fluid ascent. However, the same processes that result in low [H2S] in reservoir waters also tend to result in decreases in the ratio of 3He 4He(R) dissolved in that water. Values of R relative to this ratio in air (Ra) attain values > 15 in YNP thermal waters. To date, all of the thermal waters at YNP that have R Ra values <9 have been found to deposit sinters with relatively low gold concentrations. These include all of the thermal waters that discharge from 180-215??C reservoirs at Upper, Midway, and Lower Geyser Basins within the western part of the Yellowstone caldera, and thermal waters at Norris Geyser Basin, outside the Yellowstone caldera, where some of the waters flow directly to the surface from a reservoir where the temperature is about 300??C. A high 3He 4He ratio in thermal water discharged at the surface does not guarantee high gold concentrations in the sinter deposited by this water. Boiling with loss of steam (the gas phase takes a separate route to the surface) during rapid upflow from the shallowest reservoir to the surface decreases the [H2S] and total He dissolved in the residual liquid without appreciably changing the 3He 4He ratio. This is because the isotopic composition of the He of the initial bulk fluid is unchanged and there is too little time for much radiogenic 4He to build back into the liquid during this rapid ascent from the near-surface reservoir. However, if boiling with phase separation and loss of steam occurs deep in the system, the 3He 4He ratio in the residual liquid, now depleted in H2S and total He, will be susceptible to dilution with radiogenic 4He that is acquired during the longer residence time underground. Some or all of the Au that comes out of solution when an initial gold bisulfide complex breaks

  16. Comparison of the effectiveness of exposure to low LET helium particles (4He) and gamma rays (137Cs) on the disruption of cognitive performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rats were exposed to either Helium (4He) particles (1000 MeV/n; 0.1 – 10 cGy; head-only) or Cesium 137Cs gamma rays (50 – 400 cGy; whole body) and the effects of irradiation on cognitive performance evaluated. The results indicated that exposure to doses of 4He particles as low as 0.1 cGy disrupted...

  17. Construction of a Newly Designed Small-Size Mass Spectrometer for Helium Isotope Analysis: Toward the Continuous Monitoring of 3He/4He Ratios in Natural Fluids

    PubMed Central

    Bajo, Ken-ichi; Sumino, Hirochika; Toyoda, Michisato; Okazaki, Ryuji; Osawa, Takahito; Ishihara, Morio; Katakuse, Itsuo; Notsu, Kenji; Igarashi, George; Nagao, Keisuke

    2012-01-01

    The construction of a small-size, magnetic sector, single focusing mass spectrometer (He-MS) for the continuous, on-site monitoring of He isotope ratios (3He/4He) is described. The instrument is capable of measuring 4He/20Ne ratios dissolved in several different types of natural fluids of geochemical interest, such as groundwater and gas from hot springs, volcanoes and gas well fields. The ion optics of He-MS was designed using an ion trajectory simulation program “TRIO,” which permits the simultaneous measurement of 3He and 4He with a double collector system under a mass resolution power (M/ΔM) of >700. The presently attained specifications of He-MS are; (1) a mass resolving power of ca. 430, sufficient to separate 3He+ from interfering ions, HD+ and H3+, (2) ultra-high vacuum conditions down to 3×10−8 Pa, and (3) a sufficiently high sensitivity to permit amounts of 3He to be detected at levels as small as 10−13 cm3 STP (3×106 atoms). Long term stability for 3He/4He analysis was examined by measuring the 3He/4He standard gas (HESJ) and atmospheric He, resulting in ∼3% reproducibility and ≤5% experimental error for various amounts of atmospheric He from 0.3 to 2.3×10−6 cm3 STP introduced into the instrument. A dynamic range of measurable 3He/4He ratios with He-MS is greater than 103 which was determined by measuring various types of natural fluid samples from continental gas (with a low 3He/4He ratio down to 2×10−8) to volcanic gas (with a high 3He/4He ratio up to 3×10−5). The accuracy and precision of 3He/4He and 4He/20Ne ratios were evaluated by comparing the values with those measured using well established noble gas mass spectrometers (modified VG5400/MS-III and -IV) in our laboratory, and were found to be in good agreement within analytical errors. Usefulness of the selective extraction of He from water/gas using a high permeability of He through a silica glass wall at high temperature (700°C) is demonstrated. PMID:24349910

  18. Characterization of helium diffusion behavior from continuous heating experiments: Sample screening and identification of multiple 4He components

    NASA Astrophysics Data System (ADS)

    McDannell, K. T.; Idleman, B. D.; Zeitler, P. K.

    2015-12-01

    Old, slowly cooled apatites often yield overdispersed helium ages due to factors such as parent zonation, He implantation, radiation damage, crystal defects, and fluid inclusions. Careful mineral selection and many replicate analyses can mitigate the impact of some of these effects. However, this approach adds unnecessary costs in time and resources when dating well-behaved apatites and is generally ineffective at identifying the root cause of age dispersion and providing suitable age corrections for poorly behaved samples. We assess a new technique utilizing static-gas measurement during continuous heating as a means to rapidly screen apatite samples. In about the time required for a conventional total-gas analysis, this method can discriminate between samples showing the volume-diffusion behavior expected for apatite and those showing anomalous release patterns, inconsistent with their use in thermochronologic applications. This method may also have the potential to quantify and discriminate between the radiogenic and extraneous 4He fractions released by a sample. Continuously heated samples that outgas by volume diffusion during a linear heating schedule should produce a characteristic sigmoidal 4He fractional loss profile, with the exact shape and position of these profiles (in loss vs. heating time space) controlled by sample kinetics, grain size, and heating rate. Secondary factors such as sample zoning and alpha-loss distribution have a relatively minor impact on such profiles. Well-behaved examples such as the Durango standard and other apatites with good age reproducibility show the expected smooth, sigmoidal gas release with complete exhaustion by temperatures predicted for volume diffusion using typical apatite kinetics (e.g., by ~900˚C for linear heating at 20˚C/minute). In contrast, "bad actor" samples that do not replicate well show significant degrees of helium release deferred to higher temperatures. We report on screening results for a range of

  19. On the K- 4He → Λπ- 3He resonant and non-resonant processes

    NASA Astrophysics Data System (ADS)

    Piscicchia, K.; Wycech, S.; Curceanu, C.

    2016-10-01

    The ongoing data analyses by the AMADEUS/KLOE-2 Collaboration on the 2004-2005 KLOE data revive studies of the K ‾ nuclear absorption at low energies. The aim is to study K ‾ interactions at subthreshold energies and to search for signals of K ‾ meson nuclear states. In this paper the spectrum of the K- 4He → Λπ- 3He reaction is discussed. One - calculable - mode of decay involves P-wave intermediate Σ (1385) resonance. Another mode involves S-wave KN → Λπ amplitude which may be extracted from the experimental results. Comparison of these two allows a check of subthreshold extrapolations of multichannel K ‾ N S-wave interaction models. Given the established significance of the P wave interaction in the K ‾ N system presented here, the obtained spectra will serve for the AMADEUS/KLOE-2 data analysis, in order to properly extract the subthreshold non-resonant transition amplitude.

  20. Mutual interactions between objects oscillating in isotopically pure superfluid 4He in the T → 0 limit

    NASA Astrophysics Data System (ADS)

    Garg, D.; Efimov, V. B.; Giltrow, M.; McClintock, P. V. E.; Skrbek, L.

    2012-11-01

    We report the results of experiments to explore interactions between physically separated oscillating objects in isotopically pure superfluid 4He at T ˜ 10 mK. The investigations focused mainly on 32 kHz quartz tuning forks, but also consider a nearby 1 kHz oscillating grid. The low-drive linewidth (LDL) and resonant frequency fd of a detector fork were monitored while the maximum velocity of a transmitter fork, separated from the detector by a few mm, was varied over a wide range. Clear evidence was found for mutual interactions between the two forks, and for the influence of the grid on the forks. Monitoring the detector's LDL and fd provides evidence for a generator critical velocity in the range 0.3<υc1<1.0 cm/s for onset of the detector responses, in addition to a second critical velocity υc2˜13 cm/s probably corresponding to the production of quantum turbulence at the generator. The results are discussed, but are not yet fully understood.

  1. A "high 4He/3He" mantle material detected under the East Pacific Rise (15°4'N)

    NASA Astrophysics Data System (ADS)

    Mougel, Berengere; Moreira, Manuel; Agranier, Arnaud

    2015-03-01

    We investigate in details helium isotope data reported in Mougel et al. (2014) for 14 basaltic samples collected on the East Pacific Rise by submersible (15°4'N) where the ridge interacts with the Mathematician seamounts. Samples locations are separated by only few hundred meters across a 15 km along-axis profile. The data reveal a strong geochemical variability that has never been observed at such high spatial resolution for helium isotope compositions. Moreover, they reveal an unusually high 4He/3He mantle component also characterized by unradiogenic lead, atypical in oceanic basalts. He-Pb systematics suggests a mixture between a nonradiogenic lead and radiogenic helium pyroxenitic component, recycled from the deep continental lithosphere and the ambient peridotitic mantle. The He isotope difference between these two end-members can be interpreted as a time evolution of two distinct mantle sources after a slight (U + Th)/3He fractionation, likely due to some ancient degassing during the formation of deep continental pyroxenites.

  2. Experimental realization of the zero temperature Random Field Ising Model : the condensation of 4He in aerogels

    NASA Astrophysics Data System (ADS)

    Aubry, Geoffroy; Guyon, Laurent; Melich, Mathieu; Spathis, Panayotis; Despetis, Florence; Wolf, Pierre-Etienne

    2013-03-01

    Although widely studied, the effect of disorder on a first order phase transition is still highly debated. Numerical simulations of the T = 0 Random Field Ising Model show that magnetization evolves by avalanches, the average size of which diverges below a critical disorder (Sethna et al., PRL 70 3347 (1993)). Nevertheless, experimental evidence is scarce up to now (Berger et al., PRL 85, 4176 (2000)). In the case of the liquid gas transition in disordered porous media, the same theoretical concepts can be applied (Detcheverry et al., PRE 72 051506 (2005)). We have studied experimentally this phase transition using 4He in silica aerogels. Optical and thermodynamical measurements show that the condensation is an out of equilibrium process. We clearly observe two filling regimes separated by a critical temperature T* : below T*, filling is discontinuous (macro avalanche) whereas above T* it becomes continuous (micro avalanches). In addition, we have developed a speckle interferometry technique to detect single avalanches. We argue that our results support the disorder induced phase transition. This work was supported by ANR-06-BLAN-0098.

  3. Development of GM cryocooler separate type liquid-helium-free 3He-4He dilution refrigerator system

    NASA Astrophysics Data System (ADS)

    Yamanaka, Y.; Ito, T.; Umeno, T.; Suzuki, Y.; Yoshida, S.; Kamioka, Y.; Maehata, K.

    2009-02-01

    We developed the new liquid-helium-free dilution refrigerator system, in which the Gifford-McMahon (GM) cycle cryocooler and dilution refrigerator (DR) unit are separated. We obtained the base temperature below 50 mK in this DR system. In usual liquid-helium-free DR systems, the DR unit directly couples with GM-cryocooler in the same vacuum chamber. Therefore the mechanical vibration of GM-cryocooler is hardly removed from DR unit. In order to eliminate the vibration problem, the separated vacuum chamber contacting the GM-cryocooler is connected with the DR unit chamber by the flexible hose with length of about 1 meter. Thin flexible tubes used for circulation of the refrigerant gas and radiation shield are installed in the connection hose. The 4He gas, cooled in the GM-cryocooler unit, transfers to the DR unit throw the thin flexible tubes. After cooling the DR unit, the gas returns to GM-cryocooler unit with cooling of the radiation shield. We expect that our separate-type dilution refrigerator becomes a useful piece of apparatus for the low temperature experiments.

  4. Study of astrophysically important resonant states in 26Si by the 28Si(4He,6He)26Si reaction

    NASA Astrophysics Data System (ADS)

    Kwon, Young Kwan; Lee, C. S.; Moon, J. Y.; Lee, J. H.; Kim, J. Y.; Kubono, S.; Iwasa, N.; Inafiki, K.; Yamaguchi, H.; He, J. J.; Saito, A.; Wakabayashi, Y.; Fukijawa, H.; Amadio, G.; Khiem, L. H.; Tanaka, M.; Chen, A.; Kato, S.

    PoS(NIC-IX)024 , b, H. Yamaguchia, J. J. Hea , A. Saitoa , Y. Wakabayashia, H. Fujikawaa, G. The emission of 1.809 MeV gamma-ray from the first excited state of 26 Mg followed by beta- decay of 26 Al in its ground state (denoted as 26 Alg.s. ) has been identified by gamma-ray telescopes such the Compton Gamma-Ray Observatory (CGRO) [1]. To resolve controversy over the pos- sible sources of the observational 1.809 MeV gamma-rays, one needs accurate knowledge of the production rate of 26 Al. The 25 Al(p,γ)26Si reaction which is the competition reaction for produc- tion of 26 Alg.s. is one of the important subjects to be investigated. In this work, the astrophysically important 26 Si states above the proton threshold were studied via the 28 Si(4 He,6 He)26 Si reaction. We have preformed an angular distribution measurement using the high resolution QDD spectro- graph (PA) at Center for Nuclear Study (CNS), University of Tokyo. The experimental results and data analysis will be presented.

  5. Bare-nucleus astrophysical factor of the {sup 3}He(d,p){sup 4}He reaction via the 'Trojan horse' method

    SciTech Connect

    La Cognata, M.; Spitaleri, C.; Tumino, A.; Cherubini, S.; Lamia, L.; Musumarra, A.; Pizzone, R.G.; Rinollo, A.; Romano, S.; Typel, S.; Rolfs, C.; Schuermann, D.; Strieder, F.

    2005-12-15

    The {sup 3}He(d,p){sup 4}He reaction has been studied from E{sub c.m.}=600 keV down to astrophysical energies by means of the 'Trojan horse' method using the {sup 6}Li({sup 3}He,p{alpha}){sup 4}He three-body reaction at E{sub lab}=5 and 6 MeV. Coincidence spectra were measured in kinematic conditions favoring the quasifree {sup 3}He+{sup 2}H process. The bare astrophysical factor S{sub b}(E) for the {sup 3}He(d,p){sup 4}He reaction was extracted from the three-body cross section in the modified plane-wave Born approximation. Comparison with the S{sub b} extrapolation from the free two-body data is presented. The independent estimate of the screening potential as obtained with the present work seems to confirm the theoretical adiabatic limit.

  6. Long-distance correlation-length effects and hydrodynamics of 4He films in a Corbino geometry

    NASA Astrophysics Data System (ADS)

    Thomson, Stephen R. D.; Perron, Justin K.; Gasparini, Francis M.

    2016-09-01

    Previous measurements of the superfluid density ρs and specific heat for 4He have identified effects that are manifest at distances much larger than the correlation length ξ3 D [Perron et al., Nat. Phys. 6, 499 (2010), 10.1038/nphys1671; Perron and Gasparini, Phys. Rev. Lett. 109, 035302 (2012), 10.1103/PhysRevLett.109.035302; Perron et al., Phys. Rev. B 87, 094507 (2013), 10.1103/PhysRevB.87.094507]. We report here measurements of the superfluid density which are designed to explore this phenomenon further. We determine the superfluid fraction ρs/ρ from the resonance of 34-nm films of varying widths 4 ≤W ≤100 μ m . The films are formed across a Corbino ring separating two chambers where a thicker 268-nm film is formed. This arrangement is realized using lithography and direct Si-wafer bonding. We identify two effects in the behavior of ρs/ρ : one is hydrodynamic, for which we present an analysis, and the other is a correlation-length effect which manifests as a shift in the transition temperature Tc relative to that of a uniform 34-nm film uninfluenced by proximity effects. We find that one can collapse both ρs/ρ and the quality factor of the resonance onto universal curves by shifting Tc as Δ Tc˜W-ν . This scaling is a surprising result on two counts: it involves a very large length scale W relative to the magnitude of ξ3 D and the dependence on W is not what is expected from correlation-length finite-size scaling which would predict Δ Tc˜W-1 /ν .

  7. Human epididymis protein 4 (HE4) plays a key role in ovarian cancer cell adhesion and motility

    SciTech Connect

    Lu, Renquan; Sun, Xinghui; Xiao, Ran; Zhou, Lei; Gao, Xiang; Guo, Lin

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer We generated stable transduced HE4 overexpression and knockdown cells. Black-Right-Pointing-Pointer HE4 was associated with EOC cell adhesion and motility. Black-Right-Pointing-Pointer HE4 might have some effects on activation of EGFR-MAPK signaling pathway. Black-Right-Pointing-Pointer HE4 play an important role in EOC tumorigenicity. -- Abstract: Human epididymis protein 4 (HE4) is a novel and specific biomarker for epithelial ovarian cancer (EOC). We previously demonstrated that serum HE4 levels were significantly elevated in the majority of EOC patients but not in subjects with benign disease or healthy controls. However, the precise mechanism of HE4 protein function is unknown. In this study, we generated HE4-overexpressing SKOV3 cells and found that stably transduced cells promoted cell adhesion and migration. Knockdown of HE4 expression was achieved by stable transfection of SKOV3 cells with a construct encoding a short hairpin DNA directed against the HE4 gene. Correspondingly, the proliferation and spreading ability of HE4-expressed cells were inhibited by HE4 suppression. Mechanistically, impaired EGFR and Erk1/2 phosphorylation were observed in cells with HE4 knockdown. The phosphorylation was restored when the knockdown cells were cultured in conditioned medium containing HE4. Moreover, in vivo tumorigenicity showed that HE4 suppression markedly inhibited the growth of tumors. This suggests that expression of HE4 is associated with cancer cell adhesion, migration and tumor growth, which can be related to its effects on the EGFR-MAPK signaling pathway. Our results provide evidence of the cellular and molecular mechanisms that may underlie the motility-promoting role of HE4 in EOC progression. The role of HE4 as a target for gene-based therapy might be considered in future studies.

  8. Relation between (e, e') sum rules in 6, 7Li and 4He nuclei: Experiment and cluster model

    NASA Astrophysics Data System (ADS)

    Efros, V. D.; Timchenko, I. S.; Buki, A. Yu.

    2016-09-01

    The sums over ( e, e') spectra of 6Li and 7Li nuclei which correspond to the longitudinal sum rule are studied. It is suggested that due to the cluster structure of the lithium isotopes these sums may approximately be expressed in terms of such a sum pertaining to the α-particle. Calculation of these sums is performed in the framework of cluster models with antisymmetrization done with respect to all the nucleons. At momentum transfers higher than 0.8 fm-1 the relations expressing the A = 6 or 7 sum in terms of the A = 4 sum prove to be valid with rather high accuracy. In the region of momentum transfers around 1 fm-1 the longitudinal correlation functions of 6Li and 7Li nuclei are found to be close to that of the α-particle. Basing on this, the difference between the q values at which the high- q limit of the inelastic sum rule is reached in the 6, 7Li cases and the 4He case is explained. The experimental longitudinal sums in the range between 0.450 and 1.625 fm-1 are employed to perform comparison with the theoretical sum rule calculated in the framework of cluster models. Out of the experimental sums, those in the range between 0.750 and 1.000 fm-1 in the 6Li case and between 0.750 and 1.125 fm-1 in the 7Li case are obtained in the present work. In the 6 Li case a complete agreement between experiment and the calculated sum rule is found while in the 7Li case an agreement only at a qualitative level is observed.

  9. A method for investigation of the D(4He, γ)6Li reaction in the Ultralow energy region under a high background

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Dudkin, G. N.; Krylov, A. R.; Gazi, S.; Huran, J.; Nechaev, B. A.; Padalko, V. N.; Sadovsky, A. B.; Tuleushev, Yu. Zh.; Filipowicz, M.; Philippov, A. V.

    2016-07-01

    The cosmological lithium problem, that is, a noticeable discrepancy between the predicted and observed abundances of lithium, is in conflict with the Standard Big Bang Nucleosynthesis model. For example, the abundance of 7Li is 2-4 times smaller than predicted by the Standard Big Bang Nucleosynthesis. As to the abundance of 6Li, recent more accurate optical investigations have yielded only the upper limit on the 6Li/7Li ratio, which makes the problem of 6Li abundance and accordingly of disagreement with the Standard Big Bang Nucleosynthesis predictions less acute. However, experimental study of the D(4He, γ)6Li reaction cross section is still of current importance because there is a theoretical approach predicting its anomalously large value in the region of energies below the Standard Big Bang Nucleosynthesis energy. The work is dedicated to the measurement of the cross section for the D(4He, γ)6Li reaction proceeding in zirconium deuteride at the incident 4He+ion energy of 36 keV. The experiment is performed at a pulsed Hall plasma accelerator with an energy spread of 20% FWHM. A method for direct measurement of the background from the reaction chain D(4He, 4He)D→D(D, n)3He→(n, γ) and/or (n, n‧γ) ending with activation of the surrounding material by neutrons is proposed and implemented in the work. An upper limit on the D(4He, γ)6Li reaction cross section σ≤7·10-36 cm2 at the 90% confidence level is obtained.

  10. Anomalously High Isotope Ratio 3He/4He and Tritium in Deuterium-Loaded Metal: Evidence for Nuclear Reaction in Metal Hydrides at Low Temperature

    NASA Astrophysics Data System (ADS)

    Jiang, Song-Sheng; He, Ming; Wu, Shao-Yong; Qi, Bu-Jia

    2012-01-01

    Anomalous 3He/4He ratios in deuterium-loaded titanium samples are observed to be about 1-4 × 10-1, much greater than the values (<=10-4) in natural objects. Control experiments with the deuterium-unloaded titanium sample and original industrial deuterium gas are also carried out, but no anomalous 3He/4He values are observed. In addition, anomalous tritium in deuterium-loaded titanium samples are also observed. To explain the excess 3He and tritium in the deuterium-loaded titanium samples, it is required that the deuteron-induced nuclear reaction occurs in the samples at low temperature.

  11. NUCLEAR AND HEAVY ION PHYSICS: Measurement of the astrophysical S factor for the low energy 2H(d,γ)4He reaction

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Fu, Yuan-Yong; Zhou, Shu-Hua; Xia, Hai-Hong; Li, Cheng-Bo; Meng, Qiu-Ying

    2009-05-01

    The γ-rays and protons from an Ed = 20 keV deuteron beam incident on a D—Ti target were measured. A branching ratio of the 2H(d,γ)4 He reaction versus the 2H(d,p) 3H reaction of Γγ/Γp = (1.06 ± 0.34) × 10-7 has been obtained, and the astrophysical S factor of the 2H(d,γ)4 He reaction at the center of mass energy Ecm approx 7 keV of (6.0 ± 2.4) × 10-6 keV·b was deduced.

  12. Contributions of excited {sup 6}Li and {sup 7}Li nuclei to the production of {sup 4}He+{sup 2}H and {sup 4}He+{sup 3}H systems in {sup 16}O{sub p} collisions at a momentum of 3.25 GeV/c per nucleon

    SciTech Connect

    Olimov, K.; Glagolev, V. V.; Gulamov, K. G.; Lutpullaev, S. L.; Kurbanov, A. R.; Olimov, A. K.; Petrov, V. I.; Yuldashev, A. A.

    2013-07-15

    New experimental data on the cross sections for the yield of excited {sup 6}Li* and {sup 7}Li* nuclei and on their contributions to the production of {sup 4}He + {sup 2}H and {sup 4}He+{sup 3}H light dinuclear systems in {sup 16}O{sub p} collisions at a momentumof 3.25 A GeV/c per nucleon are presented.

  13. The {sup 3}He(e,e'p){sup 2}H and {sup 4}He(e,e'p){sup 3}H reactions at high momentum transfer

    SciTech Connect

    Ford, William P.; Schiavilla, Rocco; Van Orden, J. W.

    2014-03-01

    We present updated calculations for observables in the processes {sup 3}He(e,e'p){sup 2}H, {sup 4}He(e,e'p){sup 3}H and {sup 4}He(e-vector, e'p-vector){sup 3}H. This update entails the implementation of improved nucleon-nucleon (NN) amplitudes to describe final state interactions (FSI) within a Glauber approximation and includes full spin-isospin dependence in the profile operator. In addition, an optical potential, which has also been updated since previous work, is utilized to treat FSI for the {sup 4}He(e,e'p){sup 3}H and {sup 4}He(e-vector, e'p-vector){sup 3}H reactions. The calculations are compared with experimental data and show good agreement between theory and experiment. Comparisons are made between the various approximations in the Glauber treatment, including model dependence due to the NN scattering amplitudes, rescattering contributions, and spin dependence. We also analyze the validity of the Glauber approximation at the kinematics the data is available, by comparing to the results obtained with the optical potential.

  14. Probing the Repulsive Core of the Nucleon-Nucleon Interaction via the 4He(e,e`pN) Triple-Coincidence Reaction

    DOE PAGESBeta

    Korover, Igor; Muangma, Navaphon; Hen, Or; Shneor, Ran; Sulkosky, Vincent; Kelleher, Aidan; Gilad, Shalev; Higinbotham, Douglas; Piasetzky, Eliazer; Wood, Stephen; et al

    2014-07-01

    We studied simultaneously the 4He(e,e'p), 4He(e,e'pp), and 4He(e,e'pn) reactions at Q2=2 [GeV/c]2 and xB >1, for a (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum in a region where the nucleon-nucleon force is expected to change from predominantly tensor to repulsive. Neutron-proton pairs dominate the high-momentum tail ofmore » the nucleon momentum distributions, but their abundance is reduced as the nucleon momentum increases beyond ~500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum in the range we studied. Our data are compared with ab-initio calculations of two-nucleon momentum distributions in 4He.« less

  15. Search for the enhancement of the thermal expansion coefficient of superfluid 4HE Near T_Lambada by a heat current

    NASA Technical Reports Server (NTRS)

    Liu, Y.; Israelsson, U.; Larson, M.

    2001-01-01

    Presentation on the transition in 4He in the presence of a heat current (Q) provides an ideal system for the study of phase transitions under non-equlibrium, dynamical conditions. Many physical properties become nonlinear and Q-dependant near the transition temperature, T_Lambada.

  16. A comparison of groundwater dating with 81Kr, 36Cl and 4He in four wells of the Great Artesian Basin, Australia

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Love, A.; Purtschert, R.; Collon, P.; Loosli, H. H.; Kutschera, W.; Beyerle, U.; Aeschbach-Hertig, W.; Kipfer, R.; Frape, S. K.; Herczeg, A.; Moran, J.; Tolstikhin, I. N.; Gröning, M.

    2003-06-01

    The isotopic ratios 81Kr/Kr and 36Cl/Cl and the 4He concentrations measured in groundwater from four artesian wells in the western part of the Great Artesian Basin (GAB) in Australia are discussed. Based on radioactive decay along a water flow path the 81Kr/Kr ratios are directly converted to groundwater residence times. Results are in a range of 225-400 kyr with error bars in the order of 15% primarily due to counting statistics in the cyclotron accelerator mass spectrometer measurement. Additional uncertainties from subsurface production and/or exchange with stagnant porewaters in the confining shales appear to be of the same order of magnitude. These 81Kr ages are then used to calibrate the 36Cl and the 4He dating methods. Based on elemental analyses of rock samples from the sandstone aquifer as well as from the confining Bulldog shale the in situ flux of thermal neutrons and the corresponding 3He/ 4He and 36Cl/Cl ratios are calculated. From a comparison of: (i) the 3He/ 4He ratios measured in the groundwater samples with the calculated in situ ratios in rocks and (ii) the measured δ 37Cl ratios with the 4He concentrations measured in groundwater it is concluded that both helium and chloride are most likely added to the aquifer from sources in the stagnant porewaters of the confining shale by diffusion and/or mixing. Based on this 'working hypothesis' the 36Cl transport equation in groundwater is solved taking into account: (i) radioactive decay, (ii) subsurface production in the sandstone aquifer (with an in situ 36Cl/Cl ratio of 6×10 -15) and (iii) addition of chloride from a source in the confining shale (with a 36Cl/Cl ratio of 13×10 -15). Lacking better information it is assumed that the chloride concentration increased linearly with time from an (unknown) initial value Ci to its measured present value C= Ci+ Ca, where Ca represents the (unknown) amount of chloride added from subsurface sources. Using the 81Kr ages of the four groundwater samples and a

  17. Estimating the groundwater residence time in eskers of the Amos region, northern Quebec by 3H-3He and (U-Th/4He) methods

    NASA Astrophysics Data System (ADS)

    Boucher, Christine; Berthot, Laureline; Pinti, Daniele Luigi; Larocque, Marie; Cloutier, Vincent; Blanchette, Daniel; Castro, Maria Clara; Hall, Chris M.

    2013-04-01

    An esker is a long winding ridge of stratified sand and gravel. The eskers of the Amos region (Abitibi-Témiscamingue, Québec) that were deposited during the last deglaciation, are known to be aquifers containing drinking water of exceptional quality. Yet little is known about their hydrologic regime and exchanges with other water sources. A better understanding of these systems is necessary to assess the vulnerability of these aquifers to contaminants and to implement a management plan for these resources. A multi-isotopic study of groundwater in the eskers of the Amos region (Saint-Mathieu-Berry, Barraute and Harricana moraine) was carried out in 2011-2012. Noble gas isotopes, together with major ions chemistry and stable isotopes were used to estimate the residence time of waters, to trace fluid flow paths and to determine the atmospheric temperature at the time of the recharge took place. Measured 3He/4He ratios were primarily used to identify mixing between different water types carrying distinct helium components. The 20Ne/4He vs. 3He/4He relationship shows that waters flowing into eskers have three helium components: atmospheric, tritiogenic 3He-rich and radiogenic 4He-rich. The measured 3He/4He ratios (R) normalized to the atmospheric one (R/Ra) varies between 0.224±0.012 and 1.849±0.036. Most radiogenic 4He-rich mineralized waters are those from fractured basement rocks of Archean age. Freshwater flowing into eskers show mixing between radiogenic helium and tritiogenic 3He. A clear relationship between the well depths, salinity and the 3He/4He ratios suggests that mixing occurs between these two groundwater bodies. Tritium measurements allow the calculation of 3H-3He ages varying from 6.7±1.3 yrs to 9.7±1.3 yrs for waters flowing through the Harricana moraine. Groundwater from Saint-Mathieu de Berry esker ranges from 11.0±2.1 yrs to 32.5±1.6 yrs. The 3H-3He ages plotted against the wells depth show a linear relationship for both, the Saint

  18. 186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

    NASA Astrophysics Data System (ADS)

    Brandon, Alan D.; Graham, David W.; Waight, Tod; Gautason, Bjarni

    2007-09-01

    Picrites from the neovolcanic zones in Iceland display a range in 187Os/ 188Os from 0.1297 to 0.1381 (γ Os = + 2.1 to +8.7) and uniform 186Os/ 188Os of 0.1198375 ± 32 (2 σ). The value for 186Os/ 188Os is within uncertainty of the present-day value for the primitive upper mantle of 0.1198398 ± 16. These Os isotope systematics are best explained by ancient recycled crust or melt enrichment in the mantle source region. If so, then the coupled enrichments displayed in 186Os/ 188Os and 187Os/ 188Os from lavas of other plume systems must result from an independent process, the most viable candidate at present remains core-mantle interaction. While some plumes with high 3He/ 4He, such as Hawaii, appear to have been subjected to detectable addition of Os (and possibly He) from the outer core, others such as Iceland do not. A positive correlation between 187Os/ 188Os and 3He/ 4He from 9.6 to 19 Ra in Iceland picrites is best modeled as mixtures of 1 Ga or older ancient recycled crust mixed with primitive mantle or incompletely degassed depleted mantle isolated since 1-1.5 Ga, which preserves the high 3He/ 4He of the depleted mantle at the time. These mixtures create a hybrid source region that subsequently mixes with the present-day convecting MORB mantle during ascent and melting. This multistage mixing scenario requires convective isolation in the deep mantle for hundreds of million years or more to maintain these compositionally distinct hybrid sources. The 3He/ 4He of lavas derived from the Iceland plume changed over time, from a maximum of 50 Ra at 60 Ma, to approximately 25-27 Ra at present. The changes are coupled with distinct compositional gaps between the different aged lavas when 3He/ 4He is plotted versus various geochemical parameters such as 143Nd/ 144Nd and La/Sm. These relationships can be interpreted as an increase in the proportion of ancient recycled crust in the upwelling plume over this time period. The positive correlation between 187Os/ 188Os and

  19. Asthenosphere-lithosphere interactions in Western Saudi Arabia: Inferences from 3He/4He in xenoliths and lava flows from Harrat Hutaymah

    NASA Astrophysics Data System (ADS)

    Konrad, Kevin; Graham, David W.; Thornber, Carl R.; Duncan, Robert A.; Kent, Adam J. R.; Al-Amri, Abdullah M.

    2016-04-01

    Extensive volcanic fields on the western Arabian Plate have erupted intermittently over the last 30 Ma following emplacement of the Afar flood basalts in Ethiopia. In an effort to better understand the origin of this volcanism in western Saudi Arabia, we analyzed 3He/4He, and He, CO2 and trace element concentrations in minerals separated from xenoliths and lava flows from Harrat Hutaymah, supplemented with reconnaissance He isotope data from several other volcanic fields (Harrat Al Birk, Harrat Al Kishb and Harrat Ithnayn). Harrat Hutaymah is young (< 850 ka) and the northeasternmost of the volcanic fields. There is a remarkable homogeneity of 3He/4He trapped within most xenoliths, with a weighted mean of 7.54 ± 0.03 RA (2σ, n = 20). This homogeneity occurs over at least eight different xenolith types (including spinel lherzolite, amphibole clinopyroxenite, olivine websterite, clinopyroxenite and garnet websterite), and encompasses ten different volcanic centers within an area of ~ 2500 km2. The homogeneity is caused by volatile equilibration between the xenoliths and fluids derived from their host magma, as fluid inclusions are annealed during the infiltration of vapor-saturated magmas along crystalline grain boundaries. The notable exceptions are the anhydrous spinel lherzolites, which have a lower weighted mean 3He/4He of 6.8 ± 0.3 RA (2σ, n = 2), contain lower concentrations of trapped He, and have a distinctly depleted light rare earth element signature. 3He/4He values of ~ 6.8 RA are also commonly found in spinel lherzolites from harrats Ithnayn, Al Birk, and from Zabargad Island in the Red Sea. Olivine from non-xenolith-bearing lava flows at Hutaymah spans the He isotope range of the xenoliths. The lower 3He/4He in the anhydrous spinel lherzolites appears to be tied to remnant Proterozoic lithosphere prior to metasomatic fluid overprinting. Elevated 3He/4He in the western harrats has been observed only at Rahat (up to 11.8 RA; Murcia et al., 2013), a

  20. Analogs of the giant dipole and spin-dipole resonances in {sup 4}He and in {alpha} clusters of {sup 6,7}Li studied by the {sup 4}He,{sup 6,7}Li({sup 7}Li,{sup 7}Be{gamma}) reactions

    SciTech Connect

    Nakayama, S.; Matsumoto, E.; Fushimi, K.; Hayami, R.; Kawasuso, H.; Yasuda, K.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Asaji, S.; Ishida, T.; Kudoh, T.; Sagara, K.; Fujiwara, M.; Hashimoto, H.; Kawase, K.; Nakanishi, K.; Oota, T.; Yosoi, M.; Greenfield, M. B.

    2008-07-15

    We studied analogs of the giant dipole resonance (GDR) and spin-dipole resonance (SDR) in {sup 4}He and in the {alpha} clusters of {sup 6,7}Li via the ({sup 7}Li,{sup 7}Be{gamma}) reactions on {sup 4}He, {sup 6}Li, and {sup 7}Li at an incident energy of 455 MeV and at a scattering angle of 0 deg. by measuring spin-nonflip and spin-flip spectra. The reaction Q-values for the analogs of the GDR and SDR in the {alpha} clusters of {sup 6,7}Li were found to be more negative than those in {sup 4}He by 2.0{+-}0.5 MeV. The ratios of the cross section for the analog of the GDR to that for the analog of the SDR in {sup 4}He and in the {alpha} clusters of {sup 6}Li and {sup 7}Li were found to be the same within errors, 0.5{+-}0.1. The cross sections for the analogs of the GDR as well as those for the analogs of the SDR in the {alpha} clusters of {sup 6,7}Li were 0.6{approx}0.8 times smaller than those in {sup 4}He. These results suggest that excitations of {alpha} clusters embedded in nuclei are suppressed as compared with excitations of free {alpha} particles.

  1. {sup 4}He fragments from the {sup 14}N + {sup 12}C collision at 35 MeV/nucleon and clustering in colliding nuclei

    SciTech Connect

    Takemoto, H.; Horiuchi, H.; Engel, A.; Ono, A.

    1996-07-01

    In order to study effects of clustering of colliding nuclei in the fragmentation process, the fragmentation of the {sup 14}N+{sup 12}C reaction at 35 MeV/nucleon is analyzed by antisymmetrized molecular dynamics. It is found that {sup 4}He fragments from {sup 12}C fragmentation are much more abundant than those from {sup 14}N fragmentation. Characters of {sup 4}He fragments from {sup 12}C fragmentation are investigated and it is found that this abundance in {sup 12}C fragmentation results from the three-alpha breakup in a short time scale where the excited states with excitation energy 7{endash}15 MeV play an important role. {copyright} {ital 1996 The American Physical Society.}

  2. Solving the Large Discrepancy Between Inclusive and Exclusive Measurements of the 8Li + 4He → 11B + n Reaction Cross Section at Astrophysical Energies

    NASA Astrophysics Data System (ADS)

    La Cognata, M.; Del Zoppo, A.; Alba, R.; Cherubini, S.; Colonna, N.; Di Pietro, A.; Figuera, P.; Gulino, M.; Lamia, L.; Musumarra, A.; Pellegriti, M. G.; Pizzone, R. G.; Rolfs, C.; Romano, S.; Spitaleri, C.; Tumino, A.

    2009-12-01

    A solution of the large discrepancy existing between inclusive and exclusive measurements of the 8Li + 4He → 11B + n reaction cross section at E cm < 3 MeV is evaluated. This problem has profound astrophysical relevance for this reaction is of great interest in big bang and r-process nucleosynthesis. By means of a novel technique, a comprehensive study of all existing 8Li + 4He → 11B + n cross section data is carried out, setting up a consistent picture in which all the inclusive measurements provide the reliable value of the cross section. New unambiguous signatures of the strong branch pattern non-uniformities, near the threshold of higher 11B excited levels, are presented and their possible origin, in terms of the cluster structure of the involved excited states of 11B and 12Bnuclei, is discussed.

  3. Systematic Vibration Studies on a Cryogen-Free ^3He/^4He Dilution Refrigerator for X-ray Spectroscopy at Storage Rings

    NASA Astrophysics Data System (ADS)

    Scholz, P. A.; Kraft-Bermuth, S.; Andrianov, V.

    2016-08-01

    High-precision X-ray spectroscopy of highly charged ions at storage rings provides a sensitive test of quantum electrodynamics in strong Coulomb fields. To increase the precision of such experiments, silicon microcalorimeters have already been applied successfully. To minimize the interruption of beam times due to maintenance, a new cryogen-free ^3He/^4He dilution refrigerator has been designed and is under commissioning. However, in cryogen-free systems microphonic noise due to vibrations contributes considerably to the overall noise and may limit the detector energy resolution. Therefore, we report on systematic vibration studies on a cryogen-free ^3He/^4He dilution refrigerator which is specially adapted for experiments at storage rings.

  4. Comparative study of dose distributions and cell survival fractions for 1H, 4He, 12C and 16O beams using Geant4 and Microdosimetric Kinetic model

    NASA Astrophysics Data System (ADS)

    Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Bleicher, Marcus

    2015-04-01

    Depth and radial dose profiles for therapeutic 1H, 4He, 12C and 16O beams are calculated using the Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT). 4He and 16O ions are presented as alternative options to 1H and 12C broadly used for ion-beam cancer therapy. Biological dose profiles and survival fractions of cells are estimated using the modified Microdosimetric Kinetic model. Depth distributions of cell survival of healthy tissues, assuming 10% and 50% survival of tumor cells, are calculated for 6 cm SOBPs at two tumor depths and for different tissues radiosensitivities. It is found that the optimal ion choice depends on (i) depth of the tumor, (ii) dose levels and (iii) the contrast of radiosensitivities of tumor and surrounding healthy tissues. Our results indicate that 12C and 16O ions are more appropriate to spare healthy tissues in the case of a more radioresistant tumor at moderate depths. On the other hand, a sensitive tumor surrounded by more resistant tissues can be better treated with 1H and 4He ions. In general, 4He beam is found to be a good candidate for therapy. It better spares healthy tissues in all considered cases compared to 1H. Besides, the dose conformation is improved for deep-seated tumors compared to 1H, and the damage to surrounding healthy tissues is reduced compared to heavier ions due to the lower impact of nuclear fragmentation. No definite advantages of 16O with respect to 12C ions are found in this study.

  5. Radiation-damage-controlled He diffusion and 4He/3He spectra in apatite: an example of mutually consistent results from the Grand Canyon (Invited)

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    Recent work indicates that He diffusion from apatite is impeded by the accumulation of radiation damage from actinide decay. Supporting evidence includes laboratory diffusion measurements as well as (U-Th)/He dates positively correlated with effective uranium (eU) concentration in certain geologic situations. Here we investigate whether the radiation damage effect can be identified in 4He concentration profiles, as it must be if the system behaves as we anticipate. Apatites from nearby igneous basement samples in the Upper Gorge of the Grand Canyon showing a strong date-eU correlation were proton irradiated, step-heated, and analyzed for 4He/3He spectra. The low eU apatites with younger He dates yielded nearly flat spectra, while the high eU apatites with older He dates yielded highly rounded spectra (see Figure). This implies that the higher eU apatites were partially retaining He while the lower eU apatites were still acting as an open system. Using the RDAAM kinetic model (Flowers et al. 2009) and local geologic constraints we confirm that this behavior is consistent with the observed differences in date and eU, providing compelling evidence that both the He dates and the 4He profiles are sensitive to radiation damage accumulation. Equally importantly, the combination of multiple samples with differing eU and thus differing 4He/3He spectra yields remarkably tight constraints on the time-temperature path experienced by these rocks, from ~90oC down to < 30oC.

  6. Chaos in the classical mechanics of bound and quasi-bound HX-4He complexes with X = F, Cl, Br, CN.

    PubMed

    Gamboa, Antonio; Hernández, Henar; Ramilowski, Jordan A; Losada, J C; Benito, R M; Borondo, F; Farrelly, David

    2009-10-01

    The classical dynamics of weakly bound floppy van der Waals complexes have been extensively studied in the past except for the weakest of all, i.e., those involving He atoms. These complexes are of considerable current interest in light of recent experimental work focussed on the study of molecules trapped in small droplets of the quantum solvent (4)He. Despite a number of quantum investigations, details on the dynamics of how quantum solvation occurs remain unclear. In this paper, the classical rotational dynamics of a series of van der Waals complexes, HX-(4)He with X = F, Cl, Br, CN, are studied. In all cases, the ground state dynamics are found to be almost entirely chaotic, in sharp contrast to other floppy complexes, such as HCl-Ar, for which chaos sets in only at relatively high energies. The consequences of this result for quantum solvation are discussed. We also investigate rotationally excited states with J = 1 which, except for HCN-(4)He, are actually resonances that decay by rotational pre-dissociation. PMID:19756276

  7. Cross sections and analyzing powers for (p,n) reactions on {sup 3}He and {sup 4}He at 346 MeV

    SciTech Connect

    Ihara, E.; Wakasa, T.; Dozono, M.; Imamura, T.; Kuroita, S.; Noro, T.; Sagara, K.; Sueta, T.; Tanabe, H.; Yamada, Y.; Hatanaka, K.; Kato, M.; Matsubara, H.; Okamura, H.; Tameshige, Y.; Tamii, A.; Sakemi, Y.; Sekiguchi, K.; Suda, K.

    2008-08-15

    The cross sections and analyzing powers for (p,n) reactions on {sup 3}He and {sup 4}He have been measured at a bombarding energy of T{sub p}=346 MeV and reaction angles of {theta}{sub lab}=9.4 deg. - 27 deg. The energy transfer spectra for {sup 3}He(p,n) at large {theta}{sub lab} ({>=}16 deg.) are dominated by quasielastic contributions and can be reasonably reproduced by plane-wave impulse approximation (PWIA) calculations for quasielastic scattering. By contrast, the known L=1 resonances in {sup 4}Li are clearly observed near the threshold in the {sup 4}He(p,n) spectra. Because these contributions are remarkable at small angles, the energy spectra are significantly different from those expected for quasielastic scattering. The data are compared with the PWIA calculations, and it is found that the quasielastic contributions are dominant at large {theta}{sub lab} ({>=}22 deg.). The nuclear correlation effects on the quasielastic peak for {sup 4}He(p,n) are also discussed.

  8. A Reestimate of the Protosolar (^2^H/^1^H)_p_ ratio from (^3^He/^4^He)_SW_ solar wind measurements.

    NASA Astrophysics Data System (ADS)

    Gautier, D.; Morel, P.

    1997-07-01

    We reanalyze the inference of the protosolar abundance of deuterium made by Geiss (1993, in Origin and Evolution of the Elements, Eds., N. Prantzos, E. Vangioni-Flam, M. Casse, Cambridge University Press, p. 90) from measurements of (^3^He/^4^He)_SW_ in the solar wind. We use an evolutionary solar model with microscopic diffusion, constrained to fit the present age, radius and luminosity, as well as the observed ratio of heavy elements to hydrogen. The protosolar (^2^H/^1^H)_p_ is obtained from the best fit of (^3^He/^4^He)_SW_. Taking for the protosolar (^3^He/^4^He)_p_ the value measured in Jupiter by the Galileo probe (Niemann et al., 1996Sci...272..846N), we derive (^2^H/^1^H)_p_=(3.01+/-0.17)x10^-5^. Compared to the present interstellar medium value (Linsky et al., 1993ApJ...402..694L), this result is compatible with models of the chemical evolution of the Galaxy in the solar neighborhood; it is also marginally compatible with the Jovian (^2^H/^1^H)_J_=(5+/-2)x10^-5^ ratio measured by Galileo.

  9. Cross-section measurement for the /sup 7/Li(n,n't)/sup 4/He reaction at 14. 74 MeV

    SciTech Connect

    Smith, D.L.; Meadows, J.W.; Bretscher, M.M.; Cox, S.A.

    1984-09-01

    The cross section for the /sup 7/Li(n,n't)/sup 4/He reaction is measured at an average neutron energy of 14.74 MeV, with a resolution of 0.324 MeV, relative to the /sup 238/U neutron-fission cross section. Tritium activities for the irradiated lithium-metal samples (enriched to 99.95% in /sup 7/Li) are deduced using a liquid-scintillation counting method which relies upon the tritiated-water standard from the US National Bureau of Standards. The measured cross section ratio of /sup 7/Li(n,n't)/sup 4/He to /sup 238/U neutron fission is 0.2523 (+- 2.2%). The derived /sup 7/Li(n,n't)/sup 4/He reaction cross section is 0.301 (+- 5.3%) barn, based on the ENDF/B-V value of 1.193 (+- 4.8%) barn for the /sup 238/U neutron-fission cross section. 59 references.

  10. Improving tritium determination from environmental water samples by the 3He ingrowth method by means of an ultrapure 4He spike

    NASA Astrophysics Data System (ADS)

    Major, Zoltan; Palcsu, Laszlo; Papp, Laszlo

    2010-05-01

    Clarke et al. (1976) described a new method based on mass spectrometric measurement of 3He to deter-mine low level tritium concentrations of water samples [1]. The method consists of three major steps: 1) The water samples are put into glass bulbs. The dissolved gases including helium are removed from the water by vacuum pumping. 2) The sample are stored for several months or years so that 3He atoms are produced from tritium decay. 3) The amount of the tritiogenic 3He is measured mass spectrometrically. Since then numeru-ous laboratories adopted this method [2-5] as noble gas mass spectrometers became commercially available. The measurements are usually calibrated by means of well known air aliquots, which in size can be compared to the helium amount from the tritium sample. The 3He/4He ratio of samples can differ considerably from that of air used for standardization. For this reason it has to be kept in mind that a possible discrimination of 3He by 4He is not necessarily corrected by the air stan-dards [3]. Additionally, the mass spectrometric sensi-tivities of the different helium isotopes depend on the pressure at the ion source [6]. In case of tritium meas-urements, the overall pressure of the helium in the mass spectrometer is much lower than that of the helium from the air calibration. We use air aliquots that contain 7•10-9 to 2•10-7 ccSTP of 4He and 5•10-15 to 1.5•10-13 ccSTP of 3He. The relative standard deviations of the calibration measurements vary between 1-2 %, and the non-linearity effect is always taken into account. The over-all helium amount in the mass spectrometer in case of a tritium sample is usually less than 3•10-10 ccSTP that derives, of cource, from the 4He [5]. As the amount of the calibration sample converges to that of tritium samples, we loose the good statistical error of the 3He measurement being counted by an electro-multiplier. It seems that the large diiference of the helium pressure in the ion source between a sample

  11. Realization of a 3He-4He Vapor-Pressure Thermometer for Temperatures Between 0.65 K and 5 K at LNE-CNAM

    NASA Astrophysics Data System (ADS)

    Sparasci, F.; Pitre, L.; Truong, D.; Risegari, L.; Hermier, Y.

    2011-01-01

    In the temperature range between 0.65 K and 5 K, the International Temperature Scale of 1990 (ITS-90) is based on 3He and 4He vapor-pressure thermometers. Between 0.65 K and 1 K, the ITS-90 overlaps with the Provisional Low Temperature Scale of 2000 (PLTS-2000), defined in term of the melting pressure of 3He. Some differences, up to more than 1 mK, exist between the two scales in the overlapping interval. The LNE-CNAM has recently started the construction of a 3He-4He vapor-pressure thermometer to realize the ITS-90 in its lowest subrange at the highest degree of accuracy. The device is provided with two separate vapor-pressure chambers, one for 3He and the other for 4He, built in a single copper block, and is installed in the experimental space of a dilution refrigerator. The vapor-pressure thermometer is designed to accommodate on the same copper block several transfer standards, an acoustic thermometer, and the 3He melting-pressure thermometer. This configuration is intended for realizing calibrations of transfer standards down to 0.65 K, for investigating the possibility to extend the acoustic thermometer below 4 K, and to perform a direct comparison between the ITS-90 and the PLTS-2000 in the overlapping temperature range, in order to study their differences. The realization of the system has been recently accomplished, and this report illustrates the characteristics of such an experimental device.

  12. 2-D numerical simulations of groundwater flow, heat transfer and 4He transport — implications for the He terrestrial budget and the mantle helium heat imbalance

    NASA Astrophysics Data System (ADS)

    Castro, Maria Clara; Patriarche, Delphine; Goblet, Patrick

    2005-09-01

    Because helium and heat production results from a common source, a continental 4He crustal flux of 4.65 * 10 - 14 mol m - 2 s - 1 has been estimated based on heat flow considerations. In addition, because the observed mantle He / heat flux ratio at the proximity of mid-ocean ridges (6.6 * 10 - 14 mol J - 1 ) is significantly lower than the radiogenic production ratio (1.5 * 10 - 12 mol J - 1 ), the presence of a terrestrial helium-heat imbalance was suggested. The latter could be explained by the presence of a layered mantle in which removal of He is impeded from the lower mantle [R.K. O'Nions, E.R. Oxburgh, Heat and helium in the Earth, Nature 306 (1983) 429-431; E.R. Oxburgh, R.K. O'Nions, Helium loss, tectonics, and the terrestrial heat budget, Science 237 (1987) 1583-1588]. van Keken et al. [P.E. van Keken, C.J. Ballentine, D. Porcelli, A dynamical investigation of the heat and helium imbalance, Earth Planet, Sci. Lett. 188 (2001) 421-434] have recently claimed that the helium-heat imbalance remains a robust observation. Such conclusions, however, were reached under the assumption that a steady-state regime was in place for both tracers and that their transport properties are similar at least in the upper portion of the crust. Here, through 2-D simulations of groundwater flow, heat transfer and 4He transport carried out simultaneously in the Carrizo aquifer and surrounding formations in southwest Texas, we assess the legitimacy of earlier assumptions. Specifically, we show that the driving transport mechanisms for He and heat are of a fundamentally different nature for a high range of permeabilities ( k ≤ 10 - 16 m 2) found in metamorphic and volcanic rocks at all depths in the crust. The assumption that transport properties for these two tracers are similar in the crust is thus unsound. We also show that total 4He / heat flux ratios lower than radiogenic production ratios do not reflect a He deficit in the crust or mantle original reservoir. Instead, they

  13. Asthenosphere–lithosphere interactions in Western Saudi Arabia: Inferences from 3He/4He in xenoliths and lava flows from Harrat Hutaymah

    USGS Publications Warehouse

    Konrad, Kevin;; Graham, David W; Thornber, Carl; Duncan, Robert A; Kent, Adam J.R.; Al-Amri, Abdulla

    2016-01-01

    Elevated 3He/4He in the western harrats has been observed only at Rahat (up to 11.8 RA; Murcia et al., 2013), a volcanic field situated above thinned lithosphere beneath the Makkah-Medinah-Nafud volcanic lineament. Previous work established that spinel lherzolites at Hutaymah are sourced near the lithosphere-asthenosphere boundary (LAB), while other xenolith types there are derived from shallower depths within the lithosphere itself (Thornber, 1992). Helium isotopes are consistent with melts originating near the LAB beneath many of the Arabian harrats, and any magma derived from the Afar mantle plume currently appears to be of minor importance.

  14. Experimental and theoretical study of the {sup 2}H(d-vector{gamma}){sup 4}He reaction below E{sub c.m.}=60 keV

    SciTech Connect

    Sabourov, K.; Ahmed, M.W.; Canon, S.R.; Crowley, B.; Joshi, K.; Kelley, J.H.; Nelson, S.O.; Perdue, B.A.; Schreiber, E.C.; Sabourov, A.; Tonchev, A.; Weller, H.R.; Wulf, E.A.; Prior, R.M.; Spraker, M.C.; Hofmann, H.M.; Trini, M.

    2004-12-01

    New measurements of the analyzing powers A{sub y} and T{sub 20} have been obtained for the {sup 2}H(d,{gamma}){sup 4}He reaction at a laboratory beam energy of 115 keV. A transition matrix element analysis results in a unique solution which indicates that the reaction proceeds by 55% E2, 29% E1, and 16% M2 radiation. These results are shown to be in good agreement with the results of a new refined resonating group model calculation. The impact of these results on the extrapolated value of the astrophysical S factor for this reaction is discussed.

  15. Polarization Transfer in the 4He(e→,e'p→)3H Reaction up to Q2=2.6 (GeV/c)2

    NASA Astrophysics Data System (ADS)

    Strauch, S.; Dieterich, S.; Aniol, K.; Annand, J.; Baker, O.; Bertozzi, W.; Boswell, M.; Brash, E.; Chai, Z.; Chen, J.-P.; Christy, M.; Chudakov, E.; Cochran, A.; de Leo, R.; Ent, R.; Epstein, M.; Finn, J.; Fissum, K.; Forest, T.; Frullani, S.; Garibaldi, F.; Gasparian, A.; Gayou, O.; Gilad, S.; Gilman, R.; Glashausser, C.; Gomez, J.; Gorbenko, V.; Gueye, P.; Hansen, J.; Higinbotham, D.; Hu, B.; Hyde-Wright, C.; Ireland, D.; Jackson, C.; de Jager, C.; Jiang, X.; Jones, C.; Jones, M.; Kellie, J.; Kelly, J.; Keppel, C.; Kumbartzki, G.; Kuss, M.; Lerose, J.; Livingston, K.; Liyanage, N.; Malov, S.; Margaziotis, D.; Meekins, D.; Michaels, R.; Mitchell, J.; Nanda, S.; Nappa, J.; Perdrisat, C.; Punjabi, V.; Ransome, R.; Roché, R.; Rosner, G.; Rvachev, M.; Sabatie, F.; Saha, A.; Sarty, A.; Udias, J.; Ulmer, P.; Urciuoli, G.; van den Brand, J.; Vignote, J.; Watts, D.; Weinstein, L.; Wijesooriya, K.; Wojtsekhowski, B.

    2003-07-01

    We have measured the proton recoil polarization in the 4He(e→ ,e'p→)4H reaction at Q2=0.5, 1.0, 1.6, and 2.6 (GeV/c)2. The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.

  16. Simulation of 3He(d,p) 4He reaction and recent results of the experimental investigation of dp breakup reaction

    NASA Astrophysics Data System (ADS)

    Janek, M.; Kurilkin, P. K.; Tarjanyiova, G.; Ladygin, V. P.; Gurchin, Yu V.; Isupov, A. Yu; Karachuk, J.-T.; Khrenov, A. N.; Kurilkin, A. K.; Livanov, A. N.; Martinska, G.; Piyadin, S. M.; Reznikov, S. G.; Merts, S. P.; Batyuk, P. N.; Terekhin, A. A.; Vnukov, I. E.

    2016-02-01

    The feasibility study for the measurements of the polarization observables in the 3He(d,p) 4He reaction for DSS project using a part of the BM@N setup have been performed. Deuteron beam with energy of 1.5 GeV, magnet, 12 stations GEM tracker and TOF wall were used in simulations in order to obtain momentum resolution and to prove the separation of the secondary protons and deuterons. Summarized results of the dp breakup reactions with detection of two protons in coincidence for some kinematic configurations at energies from 300 to 500 MeV obtained in Nuclotron are presented.

  17. Performance of compact liquid helium free 3He-4He dilution refrigerator directly coupled with GM cooler in TES microcalorimeter operation

    NASA Astrophysics Data System (ADS)

    Umeno, T.; Kamioka, Y.; Yoshida, S.; Maehata, K.; Ishibashi, K.; Takasaki, K.; Tanaka, K.

    2009-02-01

    A superconducting transition edge thermosensor (TES) microcalorimeter was cooled by a compact liquid-helium-free 3He-4He dilution refrigerator with loading a Gifford-McMahon (GM) cooler for detection of LX-ray photons emitted from an 241Am source. The first and second stages of the GM cooler are directly coupled with the first and the second precool heat exchangers of a stick shaped dilution unit through copper plates in the vacuum chamber, respectively. The circulating 3He-4He gas through the precooled heat exchangers is condensed into a liquid of condense mixture by the isoenthalpic expansion through the Joule-Thomson impedance. A cascade of two mixing chambers are employed for achieving sufficient cooling power. The helium-free dilution refrigerator performs the cooling power of 20 μW at 100 mK. The TES and SQUID chips suffered from mechanical vibrations induced by a reciprocating motion of the displacer of the GM cooler. Detection signals of LX-ray photons emitted from 241Am source were observed by operating the TES microcalorimeter in severe noise environment induced by mechanical vibrations.

  18. Comparison of the Effectiveness of Exposure to Low-LET Helium Particles ((4)He) and Gamma Rays ((137)Cs) on the Disruption of Cognitive Performance.

    PubMed

    Rabin, Bernard M; Carrihill-Knoll, Kirsty L; Shukitt-Hale, Barbara

    2015-09-01

    In this study, the effects of radiation exposure on cognitive performance were evaluated. Rats were exposed to either helium ((4)He) particles (1,000 MeV/n; 0.1-10 cGy; head only) or cesium (137)Cs gamma rays (50-400 cGy; whole body), after which their cognitive performance was evaluated. The results indicated that exposure to doses of (4)He particles as low as 0.1 cGy disrupted performance in a variety of cognitive tasks, including plus-maze performance (baseline anxiety), novel location recognition (spatial performance) and operant responding on an ascending fixed-ratio reinforcement schedule (motivation and responsiveness to changes in environmental contingencies) but not on novel object recognition performance (learning and memory). In contrast, after exposure to (137)Cs gamma rays only plus-maze performance was affected. There were no significant effects on any other task. Because exposure to both types of radiation produce oxidative stress, these results indicate that radiation-produced oxidative stress may be a necessary condition for the radiation-induced disruption of cognitive performance, but it is not a sufficient condition.

  19. Dissociation of relativistic {sup 7}Be nuclei through the {sup 3}He+{sup 4}He channel on a proton target

    SciTech Connect

    Alexandrov, Yu. A.; Peresadko, N. G. Gerasimov, S. G.; Dronov, V. A.; Pisetskaya, A. V.; Fetisov, V. N.; Kharlamov, S. P.; Shesterkina, L. N.

    2015-05-15

    The differential cross section for the interaction of {sup 7}Be nuclei with protons was measured in the momentum-transfer region extending up to a value of 0.5 GeV/c at which {sup 7}Be decay to {sup 3}He and {sup 4}He fragments was not accompanied by the emergence of other charged particles. In the momentum-transfer region extending up to about 100 MeV/c, the cross section is strongly suppressed in just the same way as in the case of the dissociation of {sup 7}Li nuclei on a proton target through the {sup 3}H+{sup 4}He channel. The total reaction cross section is 10 ± 4 mb. The mean transverse-momentum transfer in observed events is 233 ± 6 MeV/c, the dispersion of its distribution being about 63 MeV/c. The interactions in question were detected in photoemulsion irradiated with {sup 7}Be nuclei originating from a charge-exchange process involving {sup 7}Li nuclei accelerated to the momentum of 1.7 GeV/c per nucleon at the nuclotron of the Joint Institute for Nuclear Research (Dubna)

  20. Comparison of the Effectiveness of Exposure to Low-LET Helium Particles ((4)He) and Gamma Rays ((137)Cs) on the Disruption of Cognitive Performance.

    PubMed

    Rabin, Bernard M; Carrihill-Knoll, Kirsty L; Shukitt-Hale, Barbara

    2015-09-01

    In this study, the effects of radiation exposure on cognitive performance were evaluated. Rats were exposed to either helium ((4)He) particles (1,000 MeV/n; 0.1-10 cGy; head only) or cesium (137)Cs gamma rays (50-400 cGy; whole body), after which their cognitive performance was evaluated. The results indicated that exposure to doses of (4)He particles as low as 0.1 cGy disrupted performance in a variety of cognitive tasks, including plus-maze performance (baseline anxiety), novel location recognition (spatial performance) and operant responding on an ascending fixed-ratio reinforcement schedule (motivation and responsiveness to changes in environmental contingencies) but not on novel object recognition performance (learning and memory). In contrast, after exposure to (137)Cs gamma rays only plus-maze performance was affected. There were no significant effects on any other task. Because exposure to both types of radiation produce oxidative stress, these results indicate that radiation-produced oxidative stress may be a necessary condition for the radiation-induced disruption of cognitive performance, but it is not a sufficient condition. PMID:26284421

  1. Solar-flare implanted He-4/He-3 and solar-proton-produced Ne and Ar concentration profiles preserved in lunar rock 61016

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Garrison, D. H.; Bogard, D. D.; Reedy, R. C.

    1993-01-01

    Depth profiles for Ne-21, Ne-22, and Ar-38 isotopes from oriented lunar rock 61016 are reported. Concentration profiles of cosmogenic GCR+SCR (Galactic cosmic ray and solar cosmic ray-produced) isotopes are determined, quantitatively resolving neon and argon produced by energetic solar flares from that produced by Galactic cosmic rays. The SCR component is resolved from the GCR component as a function of shielding, and excellent agreement is found between experimental SCR production profiles for the isotopes and theoretically calculated values. A characteristic SW He-4/He-3 ratio of 3450 +/- 81, representing energies down to as few keV/amu. In slightly deeper samples an SRF He-4/He-3 ratio of 3450 +/- 725 is found for He particles with E larger than about 1 MeV/amu. These results indicate that the isotopic composition of SF He, averaged over the long term, is energy-dependent. An implanted Ne-20/Ne-22 ratio of 12.4 is measured in unetched samples, representing E greater than 1 MeV/amu, and a ratio of 11.6 is inferred in the samples, representing E larger than about 5 MeV/amu.

  2. Kinetics of the reaction of the heaviest hydrogen atom with H2, the 4Heμ + H2 → 4HeμH + H reaction: experiments, accurate quantal calculations, and variational transition state theory, including kinetic isotope effects for a factor of 36.1 in isotopic mass.

    PubMed

    Fleming, Donald G; Arseneau, Donald J; Sukhorukov, Oleksandr; Brewer, Jess H; Mielke, Steven L; Truhlar, Donald G; Schatz, George C; Garrett, Bruce C; Peterson, Kirk A

    2011-11-14

    The neutral muonic helium atom (4)Heμ, in which one of the electrons of He is replaced by a negative muon, may be effectively regarded as the heaviest isotope of the hydrogen atom, with a mass of 4.115 amu. We report details of the first muon spin rotation (μSR) measurements of the chemical reaction rate constant of (4)Heμ with molecular hydrogen, (4)Heμ + H(2) → (4)HeμH + H, at temperatures of 295.5, 405, and 500 K, as well as a μSR measurement of the hyperfine coupling constant of muonic He at high pressures. The experimental rate constants, k(Heμ), are compared with the predictions of accurate quantum mechanical (QM) dynamics calculations carried out on a well converged Born-Huang (BH) potential energy surface, based on complete configuration interaction calculations and including a Born-Oppenheimer diagonal correction. At the two highest measured temperatures the agreement between the quantum theory and experiment is good to excellent, well within experimental uncertainties that include an estimate of possible systematic error, but at 295.5 K the quantum calculations for k(Heμ) are below the experimental value by 2.1 times the experimental uncertainty estimates. Possible reasons for this discrepancy are discussed. Variational transition state theory calculations with multidimensional tunneling have also been carried out for k(Heμ) on the BH surface, and they agree with the accurate QM rate constants to within 30% over a wider temperature range of 200-1000 K. Comparisons between theory and experiment are also presented for the rate constants for both the D + H(2) and Mu + H(2) reactions in a novel study of kinetic isotope effects for the H + H(2) reactions over a factor of 36.1 in isotopic mass of the atomic reactant.

  3. Helium and neon isotopes in phenocrysts from Samoan lavas: Evidence for heterogeneity in the terrestrial high 3He/ 4He mantle

    NASA Astrophysics Data System (ADS)

    Jackson, Matthew G.; Kurz, Mark D.; Hart, Stanley R.

    2009-10-01

    We report the first neon isotope measurements on phenocrysts from subaerial and submarine Samoan lavas. These new data complement existing Ne-isotope data from Samoan peridotite xenoliths (Poreda, R.J., Farley, K.A.,1992. Rare gases in Samoan xenoliths. Earth Planet. Sci. Lett. 113, 689 129-144). Neon isotopes were measured in magmatic phenocrysts separated from nine shield-stage lavas from 5 Samoan volcanoes, including Ofu, Ta'u, Vailulu'u, Malumalu and Savai'i. Phenocrysts from subaerial Samoan lavas have higher 20Ne/ 22Ne than submarine phenocrysts, which may suggest different atmospheric contamination mechanisms for these two different eruptive environments. Olivine phenocrysts from a subaerial Ta'u lava exhibit the highest 20Ne/ 22Ne (11.33±0.08, 1σ) value in this study. Two subaerial Samoan samples from Ofu Island with high 3He/ 4He ratios (Ofu-04-06 and Ofu-04-03; 34 and 24 Ra [ratio to atmosphere], respectively) also have elevated 20Ne/ 22Ne ratios relative to air, and in a three-isotope neon plot the Ofu samples are indistinguishable from measurements made on high 3He/ 4He lavas from Hawaii, Iceland and Galapagos. The similarity of helium and neon isotopes in Ofu and Hawaii-Iceland-Galapagos is remarkable given the distinctions in 87Sr/ 86Sr (0.70458 for Ofu vs. 0.70329-0.70368 for Hawaii-Iceland-Galapagos) and 143Nd/ 144Nd (Ofu's 0.51283 vs. 0.51294-0.51297 for Hawaii-Iceland-Galapagos) in high 3He/ 4He lavas from these localities. Thus, the occurrence of similar helium and neon isotope compositions in lavas from these 4 hotspots does not appear to be linked to their variable Sr and Nd isotope compositions, and demonstrates a complex relationship between the isotopes of noble gases and the more refractory radiogenic isotopes. Additionally, we observe strongly nucleogenic neon isotopes in one the most isotopically-enriched ( 87Sr/ 86Sr > 0.718) Samoan lavas. This observation is consistent with the presence of recycled, continentally-derived marine

  4. Determination of the {sup 22}Ne{sub nucl}/{sup 4}He{sub rad} ratio in natural uranium-rich fluorite by mass spectrometry

    SciTech Connect

    Sole, Jesus; Pi, Teresa

    2006-10-15

    A determination by noble gas mass spectrometry of {sup 22}Ne production through the combined reactions {sup 19}F({alpha},n){sup 22}Na({beta}{sup +}){sup 22}Ne and {sup 19}F({alpha},p){sup 22}Ne on natural calcium fluoride is made for the first time. Six samples of U-rich fluorite from a fluorspar deposit in Mexico were used to determine the {sup 22}Ne{sub nucl}/{sup 4}He{sub rad} ratio generated by the spontaneous decay of U during the last 32 Ma. The obtained ratio (1.33 {+-} 0.11) x10{sup -5} (95% confidence), is compared to other experimental data on natural uranium oxides and theoretical values.

  5. Vortex Shedding from an Object Moving in Superfluid ^4{He} at mK Temperatures and in a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Schoepe, W.

    2016-08-01

    Vortex shedding from a microsphere oscillating in superfluid ^4{He} at mK temperatures is compared with that from a laser beam moving in a Bose-Einstein condensate as observed by other authors. In particular, in either case a linear dependence of the shedding frequency f_v on Δ v = v - v_c is observed, where v is the velocity amplitude of the sphere or the constant velocity of the laser beam above a critical velocity v_c for the onset of turbulent flow: f_v = a Δ v , where the coefficient a is proportional to the oscillation frequency ω above some characteristic frequency ω _k and assumes a finite value for steady motion ω → 0.

  6. The halogen (F, Cl, Br, I) and H2O systematics of Samoan lavas: Assimilated-seawater, EM2 and high-3He/4He components

    NASA Astrophysics Data System (ADS)

    Kendrick, Mark A.; Jackson, Matthew G.; Hauri, Erik H.; Phillips, David

    2015-01-01

    The Samoan mantle plume samples two or more mantle components including an extreme EM2 composition with 87Sr/86Sr > 0.720 and a primitive component with high 3He/4He. The high 87Sr/86Sr melts have a unique potential to constrain the composition of the EM2 mantle end-member that is commonly attributed to subduction recycling. However, a previous study of H2O, CO2, S, F and Cl in Samoan glasses was hampered by the presence of unresolved assimilated sea water. The current study builds on the earlier work by extending the volatile database to include the trace halogens Br and I, and reporting new volatile data for additional glasses with 87Sr/86Sr up to 0.7125 and 3He/4He up to 15 Ra (Ra is the atmospheric 3He/4He ratio of 1.39 ×10-6). The selected glasses with MgO of 4.0 to 6.5 wt.% have CO2 concentrations of 4 to 200 ppm that reflect degassing of CO2 on the seafloor. The glasses contain 0.7-1.9 wt.% H2O, 880-1870 ppm F, 490-1790 ppm Cl, 1.9-7.2 ppm Br, 19-130 ppb I and 0.6-1.7 wt.% K. Correlations between the concentrations of these elements suggest the melts retain H2O concentrations close to pre-degassing values and demonstrate the melts have been variably affected by assimilation of seawater-derived brines. The brines are indicated to have had salinities of 55 ± 15 wt.% salt, F/Cl ratios close to seawater (e.g. <0.0001), Br/Cl ratios ∼ 40% higher than seawater, and I/Cl ratios ten times the seawater value. It is calculated the melts assimilated brine fractions of 0 to 0.45 wt.%, which contributed up to ∼30% of the total H2O and up to ∼70% of the total Cl in the melts. After accounting for the effects of brine assimilation, the Samoan melts are suggested to have a fairly constant magmatic Cl/K of 0.05 ± 0.2, which is lower than the median MORB value. Assimilation-corrected H2O/Ce values are not correlated with 87Sr/86Sr, but the sample with the highest 87Sr/86Sr of 0.7125 has an assimilation-corrected H2O/Ce of 83 ± 3, that is significantly lower than

  7. Primordial 4He abundance: a determination based on the largest sample of H II regions with a methodology tested on model H II regions

    NASA Astrophysics Data System (ADS)

    Izotov, Y. I.; Stasińska, G.; Guseva, N. G.

    2013-10-01

    We verified the validity of the empirical method to derive the 4He abundance used in our previous papers by applying it to CLOUDY (v13.01) models. Using newly published He i emissivities for which we present convenient fits as well as the output CLOUDY case B hydrogen and He i line intensities, we found that the empirical method is able to reproduce the input CLOUDY 4He abundance with an accuracy of better than 1%. The CLOUDY output data also allowed us to derive the non-recombination contribution to the intensities of the strongest Balmer hydrogen Hα, Hβ, Hγ, and Hδ emission lines and the ionisation correction factors for He. With these improvements we used our updated empirical method to derive the 4He abundances and to test corrections for several systematic effects in a sample of 1610 spectra of low-metallicity extragalactic H ii regions, the largest sample used so far. From this sample we extracted a subsample of 111 H ii regions with Hβ equivalent width EW(Hβ) ≥ 150 Å, with excitation parameter x = O2+/O ≥ 0.8, and with helium mass fraction Y derived with an accuracy better than 3%. With this subsample we derived the primordial 4He mass fraction Yp = 0.254 ± 0.003 from linear regression Y - O/H. The derived value of Yp is higher at the 68% confidence level (CL) than that predicted by the standard big bang nucleosynthesis (SBBN) model, possibly implying the existence of different types of neutrino species in addition to the three known types of active neutrinos. Using the most recently derived primordial abundances D/H = (2.60 ± 0.12) × 10-5 and Yp = 0.254 ± 0.003 and the χ2 technique, we found that the best agreement between abundances of these light elements is achieved in a cosmological model with baryon mass density Ωbh2 = 0.0234 ± 0.0019 (68% CL) and an effective number of the neutrino species Neff = 3.51 ± 0.35 (68% CL). Based on observations collected at the European Southern Observatory, Chile, programs 073.B-0283(A), 081.C-0113(A

  8. The 4He Total Photo-Absorption Cross Section With Two- Plus Three-Nucleon Interactions From Chiral Effective Field Theory

    SciTech Connect

    Quaglioni, S; Navratil, P

    2007-03-09

    The total photo-absorption cross section of {sup 4}He is evaluated microscopically using two- (NN) and three-nucleon (NNN) interactions based upon chiral effective field theory ({chi}EFT). The calculation is performed using the Lorentz integral transform method along with the ab initio no-core shell model approach. An important feature of the present study is the consistency of the NN and NNN interactions and also, through the Siegert theorem, of the two- and three-body current operators. This is due to the application of the {chi}EFT framework. The inclusion of the NNN interaction produces a suppression of the peak height and enhancement of the tail of the cross section. We compare to calculations obtained using other interactions and to representative experiments. The rather confused experimental situation in the giant resonance region prevents discrimination among different interaction models.

  9. Polarization transfer in the 4He(e→,e'p→)3H reaction at Q2 = 0.8 and 1.3 (GeV/c)2

    DOE PAGESBeta

    Michael Paolone; Malace, Simona P.

    2010-08-12

    Here, proton recoil polarization was measured in the quasielastic 4He(e→,e'p→)3H reaction at Q2 = 0.8 (GeV/c)2 and 1.3 (GeV/c)2 with unprecedented precision. The polarization-transfer coefficients are found to differ from those of the 1H(e→,e'p→) reaction, contradicting a relativistic distorted-wave approximation, and favoring either the inclusion of medium-modified proton form factors predicted by the quark-meson coupling model or a spin-dependent charge-exchange final-state interaction. For the first time, the polarization-transfer ratio is studied as a function of the virtuality of the proton.

  10. Heavy-ion versus {sup 3}He/{sup 4}He fusion-fission reactions: Angular momentum dependence of dissipation in nuclear fission

    SciTech Connect

    Ye, W.

    2011-09-15

    The stochastic Langevin model is employed to study dissipation properties in fission in the {sup 16}O + {sup 181}Ta {yields}{sup 197}Tl system by analyzing prescission neutron yields measured in this reaction. It has been found that the {sup 197}Tl nuclei undergo fission that is not in accordance with the standard Bohr-Wheeler statistical theory. A detailed comparison with previously published work in which fission excitation functions measured in {sup 3,4}He + {sup 197}Au {yields}{sup 200,201}Tl are shown to be in excellent agreement with the fission width formula predicted by the traditional models of nuclear fission suggests that nuclear dissipation strength may have an angular momentum dependence in addition to the known deformation and temperature dependence. Implications for the basic understanding of the observed abnormal rise in prescission particles at high energy and the need for further experimental confirmations are discussed.

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

    SciTech Connect

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

    1988-04-15

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

  12. Laser-spectroscopy measurement of the fine-structure splitting 2 3P1-2 3P2 of 4He

    NASA Astrophysics Data System (ADS)

    Feng, G.-P.; Zheng, X.; Sun, Y. R.; Hu, S.-M.

    2015-03-01

    Laser spectroscopy has been performed on a beam of neutral 4He atoms. By using transverse laser cooling and focusing, we are able to prepare a bright beam of atoms in the metastable state 2 3S1 deflected from the original effusive atomic beam. The initial state preparation is completed with optical pumping on the 2 3P1←2 3S1 transition at the wavelength of 1083 nm, followed by laser spectroscopy on the 2 3P1 ,2←2 3S1 transitions. The 2 3P1-2 3P2 fine-structure splitting is determined to be 2 291 177.69 ±0.36 kHz . The quantum interference effect is included in data extraction. This is the most precise laser spectroscopy measurement of the interval. Our result is in agreement with both the latest QED-based calculation and the most precise measurement conducted with microwave spectroscopy.

  13. A non-LTE spectral analysis of the 3He and 4He isotopes in the HgMn star κ Cancri

    NASA Astrophysics Data System (ADS)

    Maza, Natalia L.; Nieva, María-Fernanda; Przybilla, Norbert

    2014-12-01

    Aims: We present a pilot study on non-local thermodynamic equilibrium (NLTE) line-formation computations for the isotopes 3He and 4He in the mercury-manganese star κ Cancri. The impact of NLTE effects on the determination of isotopic abundances and the vertical stratification of helium in the atmosphere is investigated. Methods: Modern NLTE line-formation computations were employed to analyse a high-resolution and high signal-to-noise ratio ESO-VLT/UVES spectrum of κ Cnc. The atmospheric parameters were determined from fitting the hydrogen Balmer lines and the spectral energy distribution. Multiple He i lines were investigated, including He i λ4921 Å and λ6678 Å, which show the widest isotopic splits. Results: Half of the observed He i lines in the spectrum of κ Cnc show significant NLTE strengthening, the effects are strongest in the red lines He iλ5875 Å and He iλ6678 Å. NLTE abundances from individual He i lines are up to a factor of ~3 lower than LTE values. Helium is found to be stratified in the atmosphere of κ Cnc. While the LTE analysis indicates a step-like profile of the helium abundance, a gradual decrease with height is indicated by the NLTE analysis. A 3He/4He ratio of ~0.25-0.30 is found. With the available data it cannot be decided whether the two isotopes follow the same stratification profile, or not. Conclusions: This work implies that NLTE effects may be ubiquitous in the atmospheres of HgMn stars and may have a significant impact on abundance determinations and the interpretation of the vertical abundance stratification of elements. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 076.B-0055(A).Figures 3 and 4 are available in electronic form at http://www.aanda.org

  14. Interpretation of groundwater age tracers (CFC-12, 14C, 4He) in a mining-influenced stream-aquifer system with transient recharge dynamics.

    NASA Astrophysics Data System (ADS)

    Bourke, Sarah; Cook, Peter; Kipfer, Rolf; Dogramaci, Shawan

    2014-05-01

    Interpretation of groundwater age tracers often requires consideration of the mixing of groundwater with varying residence times. Quantification of mixing can be approached through measurement of multiple groundwater age indicators with varying ranges of temporal sensitivity, and their interpretation using lumped parameter models. However, in systems altered by mining, where recharge mechanisms are highly transient in space and time, lumped parameter models do not adequately represent the complexity of the system. In the Pilbara region of Western Australia, water abstracted during dewatering of ore-body aquifers is disposed of by discharging it into ephemeral streams and allowing it to recharge the aquifer. Because this water is essentially being recycled, stable isotopes and chloride are not useful tracers of the impact of this dewatering discharge. In contrast, gas tracers that respond rapidly to exposure to the atmosphere are more useful tracers for constraining the influence of dewatering discharge on the aquifer water balance. In this study we measured CFC-12, 14C and noble gases in production wells and transects of piezometers perpendicular to the stream. Even in samples from wells screened over intervals of 1 m, we observe combinations of tracer concentrations that indicate mixing of groundwater with contrasting residence times. For example, all samples contained measureable CFC-12 concentrations, including those with appreciable terrigenic 4He. Interpretation of these data requires consideration of the history of mining activity in the area. Stream 14C activities, which now range from 50 to 75 pMC, are a function of the dewatering discharge, and are no longer in equilibrium with the atmosphere. As a result, groundwater that recharged prior to mining operations can have higher 14C activities than groundwater that recharged through the stream in the last 10 years. The dewatering discharge has caused the stream to transition from a disconnected ephemeral

  15. Depth profiling of oxidized a-C:D Layers on Be -- A comparison of {sup 4}He RBS and {sup 28}Si ERD analysis

    SciTech Connect

    Roth, J.; Mayer, M.; Walsh, D.; Wampler, W.R.

    1997-06-01

    In applications dealing with the deposition of amorphous hydrogenated carbon layers or in the determination of the composition of deposited layers on the walls of nuclear fusion plasma experiments, the analysis of mixtures of light elements on heavy substrates is necessary. Depth profiling by means of RBS is often difficult due to the overlap of the backscattering intensities of different constituents from different depths. The erosion and reaction of deposited amorphous deuterated carbon (a-C:D) films with a Be substrate due to annealing in air poses an analytical challenge especially if simultaneously the exchange of hydrogen isotopes should be monitored. The analysis of the different recoiling atoms from collisions with heavy ions in Elastic Recoil Detection (ERD) can provide a tool which resolves all constituents in a single analysis. In the present study the composition of intermixed layers on Be containing H, D, Be, C and O has been analyzed using conventional {sup 4}He RBS at 2.2 MeV together with 2.5 MeV {sup 4}He ERD for hydrogen isotope analysis. At these energies, an overlap of signals from different constituents could be avoided in most cases. As alternative method heavy ion ERD using Si{sup 7+} ions extracted from a 5 MeV Tandem Van de Graff accelerator was investigated. At a scattering angle of 30{degree} Si ions could not be scattered into the detector and a solid state detector without protecting foil could be used. Even in the intermixed layers at terminal energies of 5 MeV the heavy constituents could be separated while signals from recoiling hydrogen and deuterium atoms could be resolved on top of the signal from the Be substrate. For the analysis of the RBS and ERD data the newly developed spectra simulation program SIMNRA has been used which includes a large data bank for scattering and nuclear reaction cross sections. The depth profiles of all constituents extracted from the simulation are compared for both methods.

  16. 7Be (n ,α )4He Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN

    NASA Astrophysics Data System (ADS)

    Barbagallo, M.; Musumarra, A.; Cosentino, L.; Maugeri, E.; Heinitz, S.; Mengoni, A.; Dressler, R.; Schumann, D.; Käppeler, F.; Colonna, N.; Finocchiaro, P.; Ayranov, M.; Damone, L.; Kivel, N.; Aberle, O.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea-Correa, J.; Barros, S.; Bécares, V.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cortés-Giraldo, M. A.; Cristallo, S.; Diakaki, M.; Domingo-Pardo, C.; Dupont, E.; Duran, I.; Fernandez-Dominguez, B.; Ferrari, A.; Ferreira, P.; Furman, W.; Ganesan, S.; García-Rios, A.; Gawlik, A.; Glodariu, T.; Göbel, K.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Harada, H.; Heftrich, T.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Katabuchi, T.; Kavrigin, P.; Kimura, A.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lerendegui, J.; Lederer, C.; Leeb, H.; Lo Meo, S.; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mazzone, A.; Mendoza, E.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Nolte, R.; Oprea, A.; Pappalardo, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Piscopo, M.; Plompen, A.; Porras, I.; Praena, J.; Quesada, J.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P.; Rubbia, C.; Ryan, J.; Sabate-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Vollaire, J.; Wallner, A.; Warren, S.; Weigand, M.; Weiß, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.; n TOF Collaboration

    2016-10-01

    The energy-dependent cross section of the 7Be (n ,α )4He reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of 7Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure 7Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si -7Be -Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

  17. A dry 3He-4He dilution refrigerator for a transition edge sensor microcalorimeter spectrometer system mounted on a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Maehata, K.; Hara, T.; Ito, T.; Yamanaka, Y.; Tanaka, K.; Mitsuda, K.; Yamasaki, N. Y.

    2014-05-01

    A dry 3He-4He dilution refrigerator (DR) was developed for a superconducting transition edge sensor (TES) microcalorimeter installed on a transmission electron microscope. This system could be used for energy dispersive X-ray spectroscopy (EDS) with an excellent energy resolution. A Gifford-McMahon (GM)-type mechanical cryocooler was used as a pre-cooler for the DR to ensure liquid helium was not consumed during operation. To reduce sound and vibrations generated by the GM cryocooler, the DR was separated from the GM cryocooler in a split system. The TES microcalorimeter was glued onto the top of a copper rod referred to as the snout, which was attached to the mixing chamber of the DR. The cooling power in the mixing chamber was 30 μW at 105 mK. The lowest temperature in the mixing chamber was 74 mK, and that at top of the snout was 86 mK. An energy resolution of 7.6 eV full width at half maximum for Si Kα X-rays of 1.74 keV was obtained by TES microcalorimeter EDS performed with the transmission electron microscope.

  18. 3He Bilayer Film Adsorbed on Graphite Plated with a Bilayer of 4He: a New Frustrated 2D Magnetic System

    NASA Astrophysics Data System (ADS)

    Neumann, Michael; Nyéki, Ján; Cowan, Brian; Saunders, John

    2006-09-01

    The heat capacity and NMR response of a 3He bilayer adsorbed on graphite plated with a bilayer of 4He have been measured over the temperature range 1-80 mK. We find that the first 3He layer requires the presence of a 3He fluid overlayer before it solidifies. Solidification is completed at a total coverage close to 9.85 nm-2, On further increasing the coverage the heat capacity maximum grows from `antiferromagnetic-like' (AFM-like) to `ferromagnetic-like' (FM-like). On the other hand, when the 3He layer first solidifies, it has a low temperature saturation magnetisation corresponding to a significant fraction of full polarisation, and this increases with increasing coverage. Furthermore the effective exchange constant inferred from the high temperature magnetisation data is always ferromagnetic. The effective exchange constants inferred from the heat capacity and magnetisation are significantly larger than those observed in the second layer of pure 3He films adsorbed on bare graphite. Otherwise there are strong similarities in the coverage dependence of the heat capacity and magnetisation, providing fresh insights into how the magnetic ground state of such 2D magnets evolves as the frustration is tuned with increasing coverage.

  19. An Improved Reaction Rate Formulation for Charged-Particle Induced Thermonuclear Reaction of {sup 2}H(d,{gamma}){sup 4}He

    SciTech Connect

    Aziz, Azni Abdul; Yusof, Norhasliza; Idris, Mahirah; Kassim, Hasan Abu

    2011-03-30

    The reaction rate formula utilized in compilations such as the Nuclear Astrophysics Compilation of Reaction Rates (NACRE) uses low energy approximation due to temperatures in stars are in the region of a few keVs. Most nuclear reaction experiments were done in MeV range and the interior temperatures of massive stars are {approx}10{sup 9} K. Hence an improved formulation for calculating the nuclear reaction rate that is applicable to high temperatures is discussed in this work. The exact tunneling probability that is applicable for all energies is obtained by solving the Schroedinger equation. This yields an enhanced expression for the astrophysical S-factor for calculating the thermonuclear reaction rate at high temperature. The thermonuclear reaction rate from this work is applied to the {sup 2}H(d,{gamma}){sup 4}He reaction and is compared with the NACRE compilation. This improved reaction rate can be included in the nuclear reaction network in a Big Bang nucleosynthesis (BBN) code or a stellar nuclear network code.

  20. Major and trace element composition of the high 3He/4He mantle: Implications for the composition of a nonchonditic Earth

    NASA Astrophysics Data System (ADS)

    Jackson, Matthew G.; Jellinek, A. Mark

    2013-08-01

    The bulk composition of the silicate portion of the Earth (BSE) has long been assumed to be tied to chondrites, in which refractory, lithophile elements like Sm and Nd exist in chondritic relative abundances. However, the 142Nd/144Nd ratios of modern terrestrial samples are 18 ± 5 ppm higher than the ordinary-chondrite reservoir, and this challenges the traditional BSE model. Here we investigate a hypothesis that this terrestrial 142Nd excess is related to a Sm/Nd ratio 6% higher than chondritic. This Sm/Nd ratio yields a superchondritic 143Nd/144Nd (˜0.5130) similar to that identified in the highest 3He/4He mantle reservoir, and we argue that this reservoir represents the BSE composition for lithophile elements. We develop a compositional model for BSE in which the elevated Sm/Nd requires a shift of 143Nd/144Nd from 0.51263 (chondritic) to 0.51300. The new BSE composition is depleted in highly incompatible elements, including K, relative to the chondrite-based BSE, and offers a solution the "missing" 40Ar paradox. This BSE compositional model requires that >83% of the mantle is depleted to form continental crust. It also implies a ˜30% reduction in BSE U, Th and K, and therefore in the current rate of radiogenic heating and, thus, a proportional increase in the heat flow delivered to surface by plate tectonics. We explore thermal history models including effects related to a newly recognized evolution in the style of plate tectonics over Earth history: The lower radiogenic heat production may delay the onset of core convection and dynamo action to as late as 3.5 Gyr.

  1. A transition-edge-sensor-based instrument for the measurement of individual He2* excimers in a superfluid 4He bath at 100 mK

    NASA Astrophysics Data System (ADS)

    Carter, Faustin Wirkus

    This dissertation is an account of the first calorimetric detection of individual He*2 excimers within a bath of superfluid 4He. When superfluid helium is subject to ionizing radiation, diatomic He molecules are created in both the singlet and triplet states. The singlet He molecules decay within nanoseconds, but due to a forbidden spin-flip the triplet molecules have a relatively long lifetime of 13 seconds in superfluid He. When He* 2 molecules decay, they emit a ~15 eV photon. Nearly all matter is opaque to these vacuum-UV photons, although they do propagate through liquid helium. The triplet state excimers propagate ballistically through the superfluid until they quench upon a surface; this process deposits a large amount of energy into the surface. The prospect of detecting both excimer states is the motivation for building a detector immersed directly in the superfluid bath. The detector used in this work is a single superconducting titanium transition edge sensor (TES). The TES is mounted inside a hermetically sealed chamber at the baseplate of a dilution refrigerator. The chamber contains superfluid helium at 100 mK. Excimers are created during the relaxation of high-energy electrons, which are introduced into the superfluid bath either in situ via a sharp tungsten tip held above the field-emission voltage, or by using an external gamma-ray source to ionize He atoms. These excimers either propagate through the LHe bath and quench on a surface, or decay and emit vacuum-ultraviolet photons that can be collected by the detector. This dissertation discusses the design, construction, and calibration of the TES-based excimer detecting instrument. It also presents the first spectra resulting from the direct detection of individual singlet and triplet helium excimers.

  2. Effectiveness of the statistical potential in the description of fermions in a worm-algorithm path-integral Monte Carlo simulation of 3He atoms placed on a 4He layer adsorbed on graphite.

    PubMed

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

    2012-01-01

    We demonstrate the effectiveness of a statistical potential (SP) in the description of fermions in a worm-algorithm path-integral Monte Carlo simulation of a few 3He atoms floating on a 4He layer adsorbed on graphite. The SP in this work yields successful results, as manifested by the clusterization of 3He, and by the observation that the 3He atoms float on the surface of 4He. We display the positions of the particles in 3D coordinate space, which reveal clusterization of the 3He component. The correlation functions are also presented, which give further evidence for the clusterization.

  3. Geochemical and 3He/ 4He evidence for mantle and crustal contributions to geothermal fluids in the western Canadian continental margin

    NASA Astrophysics Data System (ADS)

    Clark, I. D.; Phillips, R. J.

    2000-12-01

    Isotopic and geochemical evidence together with helium isotopes are used to identify contributions of deep crustal to upper mantle volatile components in thermal waters at three sites across the western North American plate margin: (1) the low heat-flow forearc of the Cascadia subduction zone; (2) the high heat-flow volcanic arc; and (3) the interior crystalline terrain of the ancestral continental margin. Western continental margin hotsprings issue 50°C, low salinity Na-Cl water and N 2 gas with 0.25% CH 4. Stable isotopes and 14C indicate local meteoric recharge during the early Holocene. Redox is buffered by sulphate reduction, suggesting that the methane originates from a deeper source. The waters have high helium contents (He/He air=30) and a 3He-excess ( R/ Rair=0.27; 3He/ 3Heair=8), representing a mixture of radiogenic 4He production in crystalline rock with >10% He from subducted oceanic crust. Geophysical data indicate fluid-filled discontinuities in the subduction zone that may provide a pathway for He, and possibly for CH 4 and a saline fluid component from depth. In the Garibaldi belt of Quaternary arc-volcanism, 60°C Na-Cl hotsprings and 200°C geothermal well waters discharge from fractures in the basement rocks. δ18O and δ2H show the thermal waters to be a mixture of local recharge with up to 8% "andesitic" water from the upper mantle. He isotopes indicate a mantle origin ( R/ Rair=6.0), with a minor crustal signature, consistent with observations in the Cascadia range to the south and at other circum-Pacific volcanic arc settings. High PCO 2, an enriched δ13C DIC, elevated 3He/CO 2 ratios and elevated Cl - are likely to be derived from subducted Juan de Fuca plate sediments and pore waters. Thermal Na-SO 4 waters (up to 58°C) from the Omineca Crystalline Belt are locally recharged and have an unusually rapid circulation time of less than 40 years. This contrasts with their high radiogenic He content (176×10 -7 cc/g) with minimal mantle input

  4. Thermal neutron calibration of a tritium extraction facility using the /sup 6/Li(n,t)/sup 4/He//sup 197/Au(n,. gamma. )/sup 198/Au cross section ratio for standardization

    SciTech Connect

    Bretscher, M.M.; Smith, D.L.

    1980-08-01

    Absolute tritium activities in a neutron-activated metallic lithium samples have been measured by liquid scintillation methods to provide data needed for the determination of capture-to-fission ratios in fast breeder reactor spectra and for recent measurements of the /sup 7/Li(n,n't)/sup 4/He cross section. The tritium extraction facility used for all these experiments has now been calibrated by measuring the /sup 6/Li(n,t)/sup 4/He//sup 197/Au/n,..gamma..)/sup 198/Au activity ratio for thermal neutrons and comparing the result with the well-known cross sections. The calculated-to-measured activity ratio was found to be 1.033 +- 0.018. 2 figures, 20 tables.

  5. Diffraction dissociation of {sup 7}Li and {sup 7}Be relativistic nuclei on proton targets through the {sup 3}H({sup 3}He)+{sup 4}He channels

    SciTech Connect

    Fetisov, V. N.

    2015-07-15

    For the fragmentation of {sup 7}Li and {sup 7}Be relativistic nuclei (with momenta of, respectively, P = 3 GeV/c and P = 1.6 GeV/c per nucleon) on proton targets through the {sup 3}H({sup 3}He) + {sup 4}He channels, the differential cross sections with respect to the momentum transfer Q to the fragments were calculated on the basis of the cluster version of Akhiezer–Glauber–Sitenko diffraction theory by employing the twobody cluster model for the {sup 7}Li ({sup 3}H + {sup 4}He) and {sup 7}Be ({sup 3}He + {sup 4}He) nuclei. These calculations, performed in the impulse approximation in the interaction of intranuclear clusters with the target nucleus, explained a strong suppression of the cross sections for reactions on protons at Q lower than 100 MeV/c and higher than 350 MeV/c and the observed irregularities in the behavior off the cross section for {sup 7}Li fragmentation on complex track-emulsion nuclei. Cross-section values close to their experimental counterparts were obtained upon setting the coefficient of two-body clustering in the {sup 7}Li and {sup 7}Be nuclei to k ≃ 0.7.

  6. Radiogenic 3He/4He Estimates and Their Effect on Calculating Plio-Pleistocene Cosmogenic 3He Ages of Alluvial-Fan Terraces in the Lower Colorado River Basin, USA

    NASA Astrophysics Data System (ADS)

    Fenton, C.; Pelletier, J.

    2005-12-01

    Several alluvial-fan terraces near Topock, AZ were created by successive entrenchment of Pliocene and Pleistocene alluvial-fan gravels shed from the adjacent Black Mountains along the lower Colorado River corridor below Hoover Dam. These fans interfinger with and overlie main-stem Colorado River sands and gravels and grade to terrace levels that correspond with pre-existing elevations of the Colorado River. Absolute dates for the ages of Quaternary deposits on the lower Colorado River are rare and cosmogenic 3He age estimates of these surfaces would help constrain the timing of aggradation and incision in the lower Colorado River corridor. We analyzed individual basalt boulders from several terrace surfaces for total 3He/4He concentrations to calculate cosmogenic 3He ages of each fan terrace; 3He/4He values, expressed as R/Ra where Ra is the 3He/4He of air, range from 0.29 to 590. Black Mountain volcanic rocks have reported K-Ar ages between 15 and 30 Ma and basalt samples from adjacent alluvial fans contain 0.42 to 47× 1012 at/g of 4He, which has likely accumulated due to nuclear processes. The amount of radiogenic 3He/4He can be significant in old rocks with young exposure ages and can complicate determination of cosmogenic 3 He content. Alpha-decay of U, Th, and their daughter isotopes produces large amounts of 4He, whereas significant amounts of radiogenic 3He are only produced through the neutron bombardment of Li and subsequent beta-decay of tritium. We measured Li, U, Th, major and rare-earth element concentrations in whole-rock basalts and mineral separates. These concentrations are used to estimate the ratio of radiogenic helium contributed to the total helium system in our samples. Li concentrations typically range from 6 to 17 ppm, with one outlier of 62 ppm. U contents range from <0.1 to 2.7 ppm and Th contents range from 0.4 to 15.3 ppm. Based on these values, our calculations predict that the average radiogenic helium (R/Ra) contributed to the total

  7. High-dynamic-range neutron time-of-flight detector used to infer the D(t,n)4He and D(d,n)3He reaction yield and ion temperature on OMEGA

    NASA Astrophysics Data System (ADS)

    Forrest, C. J.; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Romanofsky, M. H.; Sangster, T. C.; Shoup, M. J.; Stoeckl, C.

    2016-11-01

    Upgraded microchannel-plate-based photomultiplier tubes (MCP-PMT's) with increased stability to signal-shape linearity have been implemented on the 13.4-m neutron time-of-flight (nTOF) detector at the Omega Laser Facility. This diagnostic uses oxygenated xylene doped with diphenyloxazole C15H11NO + p-bis-(o-methylstyryl)-benzene (PPO + bis-MSB) wavelength shifting dyes and is coupled through four viewing ports to fast-gating MCP-PMT's, each with a different gain to allow one to measure the light output over a dynamic range of 1 × 106. With these enhancements, the 13.4-m nTOF can measure the D(t,n)4He and D(d,n)3He reaction yields and average ion temperatures in a single line of sight. Once calibrated for absolute neutron sensitivity, the nTOF detectors can be used to measure the neutron yield from 1 × 109 to 1 × 1014 and the ion temperature with an accuracy approaching 5% for both the D(t,n)4He and D(d,n)3He reactions.

  8. M-shell ionization of heavy elements by 0.1-1.0 MeV/amu {sup 1,2}H and {sup 3,4}He ions

    SciTech Connect

    Pajek, M.; Banas, D.; Braziewicz, J.; Czarnota, M.; Bienkowski, A.; Jaskola, M.; Korman, A.; Trautmann, D.; Lapicki, G.

    2006-01-15

    The M-shell ionization in high-Z atoms by low-energy light {sub 1}{sup 1}H, {sub 1}{sup 2}H, {sub 2}{sup 3}He, and {sub 2}{sup 4}He ions have been studied systematically in the energy range 0.1-1.0 MeV/amu in order to verify the available theoretical approaches describing the M-shell ionization by charged particles in asymmetric collisions. The present low-energy data, combined with our earlier results reported for M-shell ionization by hydrogen and helium ions for higher energies, form a systematic experimental basis to test the theoretical predictions of M-shell ionization based on the plane-wave Born approximation (PWBA), the semiclassical approximation (SCA), and the binary-encounter approximation (BEA). In the PWBA based approaches the energy loss (E), Coulomb deflection (C), perturbed stationary state (PSS), and relativistic (R) effects were considered within the ECPSSR theory and its recent modification, called the ECUSAR theory, in which a description of the PSS effect was corrected to account for the united- and separated-atom (USA) electron binding energy limits. In the SCA calculations with relativistic wave functions the binding effect was included only in the limiting cases of separated-atom and united-atom limits. Possible contribution of the electron capture, multiple ionization, and recoil ionization to the M-shell vacancy production, which is dominated for light ions impact by direct single ionization process, are also discussed. The universal scaling of measured M-shell x-ray production and ionization cross sections was investigated in detail. Using the present data the isotopic effect has been studied by comparing the measured M-shell ionization cross-section ratios for equal-velocity hydrogen {sub 1}{sup 1}H and {sub 1}{sup 2}H as well as helium {sub 2}{sup 3}He and {sub 2}{sup 4}He isotopes. In addition, the ratios of measured ionization cross sections for {sub 1}{sup 2}H and {sub 2}{sup 4}He were used to investigate the role of the binding

  9. Formation ages and thermal histories of fracture-filling hematite and Mn-oxide in Precambrian basement from (U-Th)/He dating and 4He/3He diffusion experiments

    NASA Astrophysics Data System (ADS)

    Reiners, P. W.; Shuster, D. L.; Evenson, N.

    2015-12-01

    Secondary Fe- and Mn-oxides in bedrock form from fluid flow associated with events that may not be preserved in stratigraphic records. (U-Th)/He chronometry is well suited for dating these phases but potential diffusive loss of 4He can complicate interpretations. Here we show that measuring He diffusion kinetics of dated samples can resolve whether ages record formation or cooling. Proterozoic (1.6 Ga) volcanics in Aravaipa Canyon, southern Arizona, contain 1.4-1.6-Ga quartz-vein-hosted hematite, as well as 1.0-1.1-Ga hematite precipitated on fractures and overlain by 20-30-Ma Mn-oxide. Hematite 4He/3He age spectra and multi-domain (MD) diffusion models are consistent with a small proportion (4-10%) of domains between 1-500 nm, larger proportions (5-15%) of 1-10 μm domains, and a majority (60-75%) of domains of 80-150 μm. Although the smallest domains would have extremely low He retentivity, models predict bulk "closure temperatures" of 180-200 °C. The 1.4-1.6-Ga quartz-vein hematite likely formed soon after eruption of its host rock, and has not been hotter than ~250 °C for Ma durations. The 1.0-1.1 Ga age of the fracture-fill hematite likely also records the timing of precipitation, but from fluids associated with nearby diabase of the same age. In contrast, the 4He/3He MD model of the 20-30-Ma Mn-oxide requires ~80% of 1-100 nm domains and 20% between 1-10 μm. Although the Mn-oxide likely formed at the same time as the hematite it coats, its age records transient heating from overlying 28-Ma volcanics. In all cases, approximate crystal sizes observed in SEM images are consistent with the predictions of MD modeling, and support the assumed kinetics of He diffusion (~147-157 kJ/mol and ~2.2×10-4 cm2/s for hematite, and ~134 kJ/mol and ~4×10-3 cm2/s for Mn-oxide).These results suggest that specular hematite can have bulk He closure temperatures at least as high as 200 °C and in some cases record precipitation; this is supported by our results on specularite

  10. Superclimb of Dislocations in Solid 4He

    NASA Astrophysics Data System (ADS)

    Kuklov, Anatoly

    2011-03-01

    Edge dislocation with superfluid core can perform superclimb -- non-conservative motion (climb) assisted by superflow along its core. Such dislocation, with Burgers vector along the C-axis, has been found in ab initio simulations of hcp solid 4. Uniform network of superclimbing dislocations can induce isochoric compressibility which is finite (in contrast to ideal solid where it vanishes) and, practically, independent of the network density. Here N is total number of atoms and is chemical potential. Such giant response has been observed by Ray and Hallock during superfluid flow events through solid He4. Study of superclimbing dislocation within the model of Granato-Lücke string, subjected to Peierls potential and to vanishing bias by , has found that exhibits wide peak in the intermediate range of temperatures (T) - above some determined by Peierls energy and below above which superfluidity of the core essentially vanishes. Non-Luttinger type behavior characterized by K scaling as some power χ of dislocation length is observed in the wide peak region. Biasing superclimbing dislocation by finite μ (due to a contact with liquid through vycor electrodes,) can induce core roughening caused by thermally assisted tunneling of jog-antijog pairs through the barrier produced by combination of Peierls potential and the bias. The threshold for this effect scales as with some power a~ 1.7. The roughening is found to be hysteretic below some temperature Thyst , with TR determining temperature of thermal roughening, He exhibits strong and narrow resonant peak leading to a dip in the core superfluid sound velocity. This mechanism is proposed as an explanation for a strong and narrow dip observed in critical superflow rate. It is found that the dip characteristics are sensitive to the bias by μ and, therefore, this can be used as a test for the proposed mechanism. It is also predicted that the dip depth at given μc ~ 1 /La should be periodic in χ with the period T . This work was supported by NSF, grants PHY1005527 and PHY0653135,and by CUNY, grant 63071-00 41.

  11. Comment on “Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation” [Phys. Fluids 25, 085101 (2013)

    SciTech Connect

    Hietala, Niklas Hänninen, Risto

    2014-01-15

    We comment on the paper by Van Gorder [“Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation,” Phys. Fluids 25, 085101 (2013)]. We point out that the flow of the normal fluid component parallel to the vortex will often lead into the Donnelly–Glaberson instability, which will cause the amplification of the Kelvin wave. We explain why the comparison to local nonlinear equation is unreasonable, and remark that neglecting the motion in the x-direction is not reasonable for a Kelvin wave with an arbitrary wavelength and amplitude. The correct equations in the general case are also derived.

  12. Pore water dating by 129I: What do 36Cl/Cl ratio, dissolved 4He concentration, δ37Cl and 129I/127I ratio suggest in the Mobara Gas field, Japan?

    NASA Astrophysics Data System (ADS)

    Mahara, Y.; Ohta, T.; Tokunaga, T.

    2010-12-01

    Total 24-brine samples were collected from hot springs and the Mobara gas wells in the Southern Kanto Gas field, where is not only the major production area for dissolved natural gas in Japan but for iodine in the world. Isotopic ratios of 129I/127I and 36Cl/Cl, and noble gases concentration dissolved into pore water were measured for estimating residence time of brine. Iodine concentration in brines increases from 10 mg/L in the northern Kanto plain to more than 100 mg/L in the south edge of the gas field, and finally reaches 170 mg/L. In contrast, the isotopic ratio of 129I/127I decreases 5×10-13 in north to 1.7×10-13 in south. Both distributions were presumably controlled by the thickness of the Kazusa group as natural gas reservoirs. The average 129I/127I ratio was estimated to be 2.33 ± 0.11×10-13 at the Mobara area. Average ages of brines are estimated to be 42 Ma by using the initial 129I/127I ratio (1.5×10-12), if the origin of 129I were cosmogenic. On the other hand, we deduced 0.2 - 0.9 Ma as the residence time of brine from comparison with the secular equilibrium 36Cl/Cl ratio (6.46 ± 2.24×10-15) for the reservoir formation of Pleistocene. The concentration of 4He dissolved in pore water in the bored rock core suggests that residence time of brines vertically ranges 0.12 - 1.05 Ma and it is also harmonized with the formation age (of 0.45 - 2.5 Ma). Furthermore, δ37Cl (- 0.14±0.13 ~ + 0.45±0.07 ‰) in pore water were measured under the chloride concentration increasing 5000 mg/L to 17000 mg/L at the depth from 642 m to 1902 m below the ground surface. The simulating analyses of δ37Cl was conducted under the boundary conditions of washing out by freshwater at the depth of 600 m below the ground surface, chloride concentration gradient of 17000/500 (mg/L/m) and diffusion alone without advection flow during the past 0.12 Ma. The fractionation factor for 35Cl and 37Cl was 1.0012 (Desauliniers et al., 1986). The analyses indicated that the

  13. Electronic Structure of Crystalline 4He at High Pressures

    SciTech Connect

    Mao, Ho Kwang; Shirley, Eric L.; Ding, Yang; Eng, Peter; Cai, Yong Q.; Chow, Paul; Xiao, Yuming; Jinfu Shu, A=Kao, Chi-Chang; Hemley, Russell J.; Kao, Chichang; Mao, Wendy L.; /Stanford U., Geo. Environ. Sci. /SLAC

    2011-01-10

    Using inelastic X-ray scattering techniques, we have succeeded in probing the high-pressure electronic structure of helium crystal at 300 K which has the widest known electronic energy bandgap of all materials, that was previously inaccessible to measurements due to the extreme energy and pressure range. We observed rich electron excitation spectrum, including a cut-off edge above 23 eV, a sharp exciton peak showing linear volume dependence, and a series of excitations and continuum at 26 to 45 eV. We determined electronic dispersion along the {Gamma}-M direction over two Brillouin zones, and provided a quantitative picture of the helium exciton beyond the simplified Wannier-Frenkel description.

  14. Electronic Structure of Crystalline [superscript 4]He at High Pressures

    SciTech Connect

    Mao, Ho Kwang; Shirley, Eric L.; Ding, Yang; Eng, Peter; Cai, Yong Q.; Chow, Paul; Xiao, Yuming; Shu, Jinfu; Hemley, Russell J.; Kao, Chichang; Mao, Wendy L.

    2010-11-12

    Using inelastic x-ray scattering techniques, we have succeeded in probing the high-pressure electronic structure of helium at 300 K. Helium has the widest known valence-conduction band gap of all materials a property whose high-pressure response has been inaccessible to direct measurements. We observed a rich electron excitation spectrum, including a cutoff edge above 23 eV, a sharp exciton peak showing linear volume dependence, and a series of excitations and continuum at 26 to 45 eV. We determined the electronic dispersion along the {Gamma}-M direction over two Brillouin zones, and provided a quantitative picture of the helium exciton beyond the simplified Wannier-Frenkel description.

  15. Spectroscopy of Mn atoms isolated in solid {sup 4}He

    SciTech Connect

    Moroshkin, P. Lebedev, V.; Weis, A.

    2014-06-07

    We present an experimental study of the laser-induced luminescence spectra of Mn atoms in solid helium matrices. We observe transitions of the valence electron and of inner-shell electrons. We find that the Mn-He interaction perturbs the inner-shell transitions to a lesser extent than the valence-electron transitions. The observed lineshapes of the inner-shell transitions of Mn are similar to those of an inner-shell transition in Ba studied earlier. At the same time, they are more strongly perturbed than the corresponding transitions in Au and Cu under the same conditions. We suggest a qualitative explanation of these observations based on the atomic bubble model. Our results also suggest that the inner-shell transitions of Mn in solid He are more strongly perturbed than the same lines of Mn isolated in solid Ar or Kr matrices.

  16. Magnetically driven cold valve for {sup 4}He

    SciTech Connect

    Bueno, J.; Blaauwgeers, R.; Partapsing, R.; Taminiau, I.; Jochemsen, R.

    2006-08-15

    We have designed a low temperature valve for liquid helium, which uses a magnetic field gradient and a permanent magnet to close. For closing, it presses a small ruby ball onto a Torlon seat. We present a small valve that is easy to build and easily controlled via two wires. It has a fast response, reliable, and has the advantage that there is no dead volume change on closing and no additional helium line is required to operate.

  17. Infrared spectroscopy of HOOO and DOOO in 4He nanodroplets

    NASA Astrophysics Data System (ADS)

    Raston, Paul L.; Liang, Tao; Douberly, Gary E.

    2012-11-01

    The HOOO hydridotrioxygen radical and its deuterated analog (DOOO) have been isolated in helium nanodroplets following the in situ association reaction between OH and O2. The infrared spectrum in the 3500-3700 cm-1 region reveals bands that are assigned to the ν1 (OH stretch) fundamental and ν1 + ν6 (OH stretch plus torsion) combination band of the trans-HOOO isomer. The helium droplet spectrum is assigned on the basis of a detailed comparison to the infrared spectrum of HOOO produced in the gas phase [E. L. Derro, T. D. Sechler, C. Murray, and M. I. Lester, J. Chem. Phys. 128, 244313 (2008), 10.1063/1.2945872]. Despite the characteristic low temperature and rapid cooling of helium nanodroplets, there is no evidence for the formation of a weakly bound OH-O2 van der Waals complex, which implies the absence of a kinetically significant barrier in the entrance channel of the reaction. There is also no spectroscopic evidence for the formation of cis-HOOO, which is predicted by theory to be nearly isoenergetic to the trans isomer. Under conditions that favor the introduction of multiple O2 molecules to the droplets, bands associated with larger H/DOOO-(O2)n clusters are observed shifted ˜1-10 cm-1 to the red of the trans-H/DOOO ν1 bands.

  18. Electronic Structure of Crystalline 4He at High Pressure

    SciTech Connect

    Mao, H.K.; Cai, Y.; Shirley, E.L.; Ding, Y.; Eng, P.; Chow, P.; Xiao, Y.; Shu, J.; Hemley, R.J.; Kao, C.C.; Mao, W.L.

    2010-10-29

    Using inelastic x-ray scattering techniques, we have succeeded in probing the high-pressure electronic structure of helium at 300 K. Helium has the widest known valence-conduction band gap of all materials a property whose high-pressure response has been inaccessible to direct measurements. We observed a rich electron excitation spectrum, including a cutoff edge above 23 eV, a sharp exciton peak showing linear volume dependence, and a series of excitations and continuum at 26 to 45 eV. We determined the electronic dispersion along the {Gamma}-M direction over two Brillouin zones, and provided a quantitative picture of the helium exciton beyond the simplified Wannier-Frenkel description.

  19. 4He glass phase: A model for liquid elements

    NASA Astrophysics Data System (ADS)

    Tournier, Robert F.; Bossy, Jacques

    2016-08-01

    The specific heat of liquid helium confined under pressure in nanoporous material and the formation, in these conditions, of a glass phase accompanied by latent heat are known. These properties are in good agreement with a recent model predicting, in liquid elements, the formation of ultrastable glass having universal thermodynamic properties. The third law of thermodynamics involves that the specific heat decreases at low temperatures and consequently the effective transition temperature of the glass increases up to the temperature where the frozen enthalpy becomes equal to the predicted value. The glass residual entropy is about 23.6% of the melting entropy.

  20. Dose and dose averaged LET comparison of {sup 1}H, {sup 4}He, {sup 6}Li, {sup 8}Be, {sup 10}B, {sup 12}C, {sup 14}N, and {sup 16}O ion beams forming a spread-out Bragg peak

    SciTech Connect

    Kantemiris, I.; Karaiskos, P.; Papagiannis, P.; Angelopoulos, A.

    2011-12-15

    Purpose: Modern clinical accelerators are capable of producing ion beams from protons up to neon. This work compares the depth dose distribution and corresponding dose averaged linear energy transfer (LET) distribution, which is related to the biological effectiveness, for different ion beams ({sup 1}H, {sup 4}He, {sup 6}Li, {sup 8}Be, {sup 10}B, {sup 12}C, {sup 14}N, and {sup 16}O) using multi-energetic spectra in order to configure spread-out Bragg peaks (SOBP). Methods: Monte Carlo simulations were performed in order to configure a 5 cm SOBP at 8 cm depth in water for all the different ion beams. Physical dose and dose averaged LET distributions as a function of depth were then calculated and compared. The superposition of dose distribution of all ions is also presented for a two opposing fields configuration. Additional simulations were performed for {sup 12}C beams to investigate the dependence of dose and dose averaged LET distributions on target depth and size, as well as beam configuration. These included simulations for a 3 cm SOBP at 7, 10, and 13 cm depth in water, a 6 cm SOBP at 7 depth in water, and two opposing fields of 6 cm SOBP. Results: Alpha particles and protons present superior physical depth dose distributions relative to the rest of the beams studied. Dose averaged LET distributions results suggest higher biological effectiveness in the target volume for carbon, nitrogen and oxygen ions. This is coupled, however, with relatively high LET values--especially for the last two ion species--outside the SOBP where healthy tissue would be located. Dose averaged LET distributions for {sup 8}Be and {sup 10}B beams show that they could be attractive alternatives to {sup 12}C for the treatment of small, not deeply seated lesions. The potential therapeutic effect of different ion beams studied in this work depends on target volume and position, as well as the number of beams used. Conclusions: The optimization of beam modality for specific tumor cites

  1. T(T,4He)2n and 3He(3He,4He)2p Reactions and the Energy Dependence of Their Mechanisms

    NASA Astrophysics Data System (ADS)

    Bacher, Andrew; McNabb, Dennis; Brune, Carl; Sayre, Dan; Hale, Gerry; Frenje, Johan; Gatu Johnson, Maria

    2015-10-01

    We have studied the T(T,alpha)2n reaction because it is the charge symmetric analog to the 3He(3He,alpha)2p reaction which completes the most direct mode of the p-p chain in stellar interiors. These reactions lead to three-body final states whose energy spectrum shapes are dominated by the strong nucleon-alpha interaction and the weaker nucleon-nucleon interaction. These experiments were done at OMEGA at the University of Rochester and at the NIF at Lawrence Livermore Lab. We will focus on two features: (1) the excitation energy dependence of the reaction mechanism and (2) the center-of-mass energy dependence of the reaction mechanism. At stellar energies (OMEGA and the NIF) we find that the shape of the neutron spectrum peaks in the middle. The n-alpha 1/2-excited state is about two times stronger than the n-alpha 3/2-ground state. For the 3He+3He reaction (at CalTech), the proton spectrum peaks at the high end. The p-alpha 3/2-state is about two times stronger than the 1/2-state. This difference in the spectrum shape is explained by theoretical models which include the interference between the two identical fermions in the final state. At CalTech we have angular distributions of the 3He+3He reaction from 2 MeV to 18 MeV. We see the p-wave strength increasing.

  2. Universality of the Phonon-Roton Spectrum in Liquids and Superfluidity of 4He

    NASA Astrophysics Data System (ADS)

    Bobrov, Viktor; Trigger, Sergey; Litinski, Daniel

    2016-06-01

    Based on numerous experimental data on inelastic neutron and X-ray scattering in liquids, we assert that the phonon-roton spectrum of collective excitations, predicted by Landau for superfluid helium, is a universal property of the liquid state. We show that the existence of the roton minimum in the spectrum of collective excitations is caused by the short-range order in liquids. Using the virial theorem, we assume that one more branch of excitations should exist in He II, whose energy spectrum differs from the phonon-roton spectrum. Such excitations are associated with the pole of single-particle Green function, which can have a gap at small values of momenta.

  3. Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

    NASA Astrophysics Data System (ADS)

    Broderick, Bernadette M.; McCaslin, Laura; Moradi, Christopher P.; Stanton, John F.; Douberly, Gary E.

    2015-04-01

    Singlet dihydroxycarbene ( HO C ̈ OH ) is produced via pyrolytic decomposition of oxalic acid, captured by helium nanodroplets, and probed with infrared laser Stark spectroscopy. Rovibrational bands in the OH stretch region are assigned to either trans,trans- or trans,cis-rotamers on the basis of symmetry type, nuclear spin statistical weights, and comparisons to electronic structure theory calculations. Stark spectroscopy provides the inertial components of the permanent electric dipole moments for these rotamers. The dipole components for trans, trans- and trans, cis-rotamers are (μa, μb) = (0.00, 0.68(6)) and (1.63(3), 1.50(5)), respectively. The infrared spectra lack evidence for the higher energy cis,cis-rotamer, which is consistent with a previously proposed pyrolytic decomposition mechanism of oxalic acid and computations of HO C ̈ OH torsional interconversion and tautomerization barriers.

  4. The heat Capacity of (sup 4)He Under Rotation Near T(wavelength)

    NASA Technical Reports Server (NTRS)

    Mukharsky, Yury M.; Chui, Talso C. P.; Mukhopadhyay, Ranjan

    1996-01-01

    The Lambda-transition in liquid helium has become a model for phase transitions. The transition with no counterflow between normal fluid and superfluid is rather well studied and understood in terms of renormalization group theory. Broken gauge symmetry gives rise to a new thermodynamic degree of freedom below the superfluid transition.

  5. Spectroscopy of gold atoms isolated in liquid and solid 4He matrices.

    PubMed

    Moroshkin, P; Lebedev, V; Weis, A

    2013-09-14

    We present a systematic experimental study of absorption and fluorescence spectra of Au atoms in bulk liquid and solid helium matrices. The results are compared to the spectra of Cu atoms studied earlier. We investigate the dependence of the observed spectral lineshapes on the helium pressure. The observed splitting of the 5d(10)6p - 5d(9)6s(2) transitions of Au in hcp solid He gives evidence for an anisotropic trapping site structure formed either by a non-spherical atomic bubble or a four-vacancy center.

  6. Thermal equilibration times in very dilute superfluid mixtures of {sup 3}He in {sup 4}He

    SciTech Connect

    Murphy, D.; Meyer, H.

    1993-04-01

    The authors analyze the time dependence of the observed temperature difference {Delta}T(t) between the warmer and the colder parallel plates bounding a fluid layer (height h) after switching on and off the heat current through this layer. From the measurements of {Delta}T(t) in the steady state, the thermal conductivity {Kappa}{sub eff} is obtained after correction for the boundary resistance. Measurements include those for cell spacings 0.5

  7. Infrared spectroscopy of HOOO and DOOO in {sup 4}He nanodroplets

    SciTech Connect

    Raston, Paul L.; Liang Tao; Douberly, Gary E.

    2012-11-14

    The HOOO hydridotrioxygen radical and its deuterated analog (DOOO) have been isolated in helium nanodroplets following the in situ association reaction between OH and O{sub 2}. The infrared spectrum in the 3500-3700 cm{sup -1} region reveals bands that are assigned to the {nu}{sub 1} (OH stretch) fundamental and {nu}{sub 1}+{nu}{sub 6} (OH stretch plus torsion) combination band of the trans-HOOO isomer. The helium droplet spectrum is assigned on the basis of a detailed comparison to the infrared spectrum of HOOO produced in the gas phase [E. L. Derro, T. D. Sechler, C. Murray, and M. I. Lester, J. Chem. Phys. 128, 244313 (2008)]. Despite the characteristic low temperature and rapid cooling of helium nanodroplets, there is no evidence for the formation of a weakly bound OH-O{sub 2} van der Waals complex, which implies the absence of a kinetically significant barrier in the entrance channel of the reaction. There is also no spectroscopic evidence for the formation of cis-HOOO, which is predicted by theory to be nearly isoenergetic to the trans isomer. Under conditions that favor the introduction of multiple O{sub 2} molecules to the droplets, bands associated with larger H/DOOO-(O{sub 2}){sub n} clusters are observed shifted {approx}1-10 cm{sup -1} to the red of the trans-H/DOOO {nu}{sub 1} bands.

  8. Phase conversion and interface growth in phase-separated 3He - 4He liquid mixtures

    NASA Astrophysics Data System (ADS)

    Abe, Haruka; Satoh, Takeo; Burmistrov, Serguei N.

    2005-10-01

    We have developed a method for measuring the transmission coefficient of a sound propagating through the interface in phase-separated He3-He4 liquid mixtures. The method and the results are described with discussions by examining the phase-conversion process of He3 quasiparticles driven to flow across the interface. From the data, we have determined the kinetic growth coefficient of the interface, ξ(T,P,ω) , as a function of temperature, pressure, and frequency. The temperature range of the present investigation is about 2-100mK at the pressure mainly around 1bar with sound frequency 9.64, 14.4, and 32.4MHz . The main specific features observed for the kinetic growth coefficient are, as follows: (i) there is a maximum at some temperature Tm(ω) depending on the frequency, (ii) above Tm(ω) , ξ decreases with the increase of temperature as ∝ω5/2T-3 , and (iii) below Tm(ω) , ξ becomes frequency independent and diminishes as a cube of temperature, T3 .

  9. Interactions of Low-Energy Spin-Polarized ^4He^+ Ions with Au(100)

    NASA Astrophysics Data System (ADS)

    Bixler, D. L.; Lancaster, J. C.; Popple, R. A.; Dunning, F. B.; Walters, G. K.

    1998-05-01

    A spin polarized He^+ ion source has been developed to study the dynamics of ion-surface interactions. The He^+ ions are produced by Penning ionization in collisions between electron-spin-polarized He(2^3S) metastable atoms contained in a weak rf-excited discharge. The ions are extracted from the discharge and focused onto a clean Au(100) surface using a series of electrostatic lenses. The impact energy can be varied from <=10eV to >=650eV and typical beam polarizations are 10-15%. Measurements of the polarization of electrons ejected from the surface as a result of Auger neutralization reveal spin correlation that can be explained by considering the local perturbation in the surface electronic structure induced by the presence of the (polarized) He^+ ion. The calculated induced densities of states are spin dependent and exhibit sharp Kondo-like features near the Fermi level. These features, and their influence on Auger neutralization, are being further explored through measurements at several different incident ion energies. *This research is support by the U. S. Department of Energy and the Robert A. Welch Foundation.

  10. Theory of neutron scattering from superfluid 4He at finite temperatures

    NASA Astrophysics Data System (ADS)

    Talbot, E.; Griffin, A.

    1984-03-01

    The dynamic structure factor S(Q-->,ω) for a Bose-condensed system is calculated microscopically at temperatures where there are a significant number of thermally excited quasiparticles present. Our work is based on the one-loop diagrammatic approximation, which has been used by Wong and Gould to discuss the low-temperature limit. In our numerical calculations (for Q=0.35 and 0.8 Å-1) of proper, irreducible quantities, we use the Bogoliubov approximation for the coherence factors in conjunction with the experimentally determined quasiparticle spectrum. We find that at high temperatures, the collisionless phonon resonance exhibited by S(Q-->,ω) has a width which increases with the number of thermally excited rotons, in rough agreement with the neutron scattering data of Cowley and Woods as well as those of Woods and Svensson. Our results are compared with those based on a phenomenological treatment of the phonon-roton coupling.

  11. Experimental study of zero sound and single-particle excitations in 4He

    NASA Astrophysics Data System (ADS)

    Kalinin, Ivan; Lauter, Hans; Puchkov, Alexander

    2006-11-01

    Extra intensity was found slightly above the energy of the phonon dispersion curve in the Q-range of 0.3-0.8 Å -1 of the scattering law S( Q, ω) of bulk superfluid helium in experiments performed on IN6 (ILL, France) and DIN-2PI (IBR-2, Russia) by inelastic neutron scattering. The aim of the present experiment is to study the temperature dependence of this extra intensity in order to elucidate the origin of this feature. The measurement of S( Q, ω) was performed on IN6 at 12 temperatures between 1 and 2.2 K at an incoming wavelength of 5.12 Å in the Q-range of 0.2-2.1 Å -1. The measurement at T=1.5 K was used for the extraction of the multiphonon part. The multiphonon part at 1.5 K and the one-phonon part, fitted by the DHO-function as a function of temperature, have been subtracted from the experimental S( Q, ω) at T>1.5 K and the remaining “extra intensity” temperature behavior has been analyzed. The analysis shows that the intensity of the “extra peak” increases with the temperature and exhibits interesting behavior when crossing the lambda-transition. In the frame of the Glyde-Griffin-Svensson model [H.R. Glyde, A. Griffin, Phys. Rev. Lett. 65 (1990)1454] four physically distinct contributions have been enumerated, which can be discussed in view of the temperature dependence of the “extra peak”.

  12. Design and performance of a 4He-evaporator at <1.0 K

    NASA Astrophysics Data System (ADS)

    Das, N. K.; Pradhan, J.; Naser, Md. Z. A.; Roy, A.; Mandal, B. Ch.; Mallik, C.; Bhandari, R. K.

    2012-12-01

    A helium evaporator for obtaining 1 K temperature has been built and tested in laboratory. This will function primarily as the precooling stage for the circulating helium isotopic gas mixture. This works on evaporative cooling by way of pumping out the vapour from the top of the pot. A precision needle valve is used initially to fill up the pot and subsequently a permanent flow impedance maintains the helium flow from the bath into the pot to replenish the evaporative loss of helium. Considering the cooling power of 10 mW @1.0 K, a 99.0 cm3 helium evaporator was designed, fabricated from OFE copper and tested in the laboratory. A pumping station comprising of a roots pump backed by a dry pump was used for evacuation. The calibrated RuO thermometer and kapton film heater were used for measuring the temperature and cooling power of the system respectively. The continuously filled 1 K bath is tested in the laboratory and found to offer a temperature less than 1.0 K by withdrawing vapour from the evaporator. In order to minimize the heat load and to prevent film creep across the pumping tube, size optimization of the pumping line and pump-out port has been performed. The results of test run along with relevant analysis, mechanical fabrication of flow impedance are presented here.

  13. Measurement of the Parity-Violating Neutron Spin Rotation in 4He

    PubMed Central

    Bass, C. D.; Dawkins, J. M.; Luo, D.; Micherdzinska, A.; Sarsour, M.; Snow, W. M.; Mumm, H. P.; Nico, J. S.; Huffman, P. R.; Markoff, D. M.; Heckel, B. R.; Swanson, H. E.

    2005-01-01

    In the meson exchange model of weak nucleon-nucleon (NN) interactions, the exchange of virtual mesons between the nucleons is parameterized by a set of weak meson exchange amplitudes. The strengths of these amplitudes from theoretical calculations are not well known, and experimental measurements of parity-violating (PV) observables in different nuclear systems have not constrained their values. Transversely polarized cold neutrons traveling through liquid helium experience a PV spin rotation due to the weak interaction with an angle proportional to a linear combination of these weak meson exchange amplitudes. A measurement of the PV neutron spin rotation in helium (φPV (n,α)) would provide information about the relative strengths of the weak meson exchange amplitudes, and with the longitudinal analyzing power measurement in the p + α system, allow the first comparison between isospin mirror systems in weak NN interaction. An earlier experiment performed at NIST obtained a result consistent with zero: φPV (n,α) = (8.0 ±14(stat) ±2.2(syst)) ×10−7 rad / m[1]. We describe a modified apparatus using a superfluid helium target to increase statistics and reduce systematic effects in an effort to reach a sensitivity goal of 10−7 rad/m. PMID:27308122

  14. Reactive intermediates in {sup 4}He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

    SciTech Connect

    Broderick, Bernadette M.; Moradi, Christopher P.; Douberly, Gary E.; McCaslin, Laura; Stanton, John F.

    2015-04-14

    Singlet dihydroxycarbene (HOC{sup ¨}OH) is produced via pyrolytic decomposition of oxalic acid, captured by helium nanodroplets, and probed with infrared laser Stark spectroscopy. Rovibrational bands in the OH stretch region are assigned to either trans,trans- or trans,cis-rotamers on the basis of symmetry type, nuclear spin statistical weights, and comparisons to electronic structure theory calculations. Stark spectroscopy provides the inertial components of the permanent electric dipole moments for these rotamers. The dipole components for trans, trans- and trans, cis-rotamers are (μ{sub a}, μ{sub b}) = (0.00, 0.68(6)) and (1.63(3), 1.50(5)), respectively. The infrared spectra lack evidence for the higher energy cis,cis-rotamer, which is consistent with a previously proposed pyrolytic decomposition mechanism of oxalic acid and computations of HOC{sup ¨}OH torsional interconversion and tautomerization barriers.

  15. Proposed Measurement of the Parity-Violating Neutron Spin Rotation in 4He

    SciTech Connect

    Micherdzinska, A. M.; Bass, C. D.; Dawkins, J. M.; Findley, T. D.; Horton, J. C.; Luo, D.; Sarsour, M.; Snow, W. M.; Heckel, B. R.; Swanson, H. E.; Markoff, D. M.

    2006-07-11

    Weak interactions between u and d quarks induce weak interactions between nucleons. These weak-interaction effects can be isolated from strong interactions using parity-violation (PV). The nucleon-nucleon (NN) weak interaction amplitudes are constrained by neither theory nor experiment. We describe a proposed measurement of PV neutron spin rotation in liquid helium {phi}PV(n,{alpha}) that is scheduled to run in 2006 with a sensitivity of 3x10-7 rad/m.

  16. Phase-Slip Avalanches in the Superflow of {sup 4}He through Arrays of Nanosize Apertures

    SciTech Connect

    Pekker, David; Barankov, Roman; Goldbart, Paul M.

    2007-04-27

    In response to recent experiments by the Berkeley group, we construct a model of superflow through an array of nanosize apertures that incorporates two basic ingredients: (1) disorder associated with each aperture having its own random critical velocity, and (2) effective interaperture coupling, mediated through the bulk superfluid. As the disorder becomes weak there is a transition from a regime where phase slips are largely independent to a regime where interactions lead to system-wide avalanches of phase slips. We explore the flow dynamics in both regimes, and make connections to the experiments.

  17. Laser spectroscopy of thulium atoms implanted in liquid and solid 4He

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kiyoshi; Hatakeyama, Atsushi; Koichi, Gosyono-O.; Wada, Shigeaki; Takahashi, Yoshiro; Yabuzaki, Tsutomu

    1997-07-01

    The excitation, emission spectra, and decay curves of the emission intensity of thulium atoms implanted in liquid and solid helium were observed in the presence and absence of an external magnetic field. The observed narrow line (width ~0.1 nm) of the excitation spectrum at 590.60 nm is assigned as a zero-phonon transition from the electronic ground state 4f13(2Fo7/2)6s2, which indicates that the transition between the inner shells is weakly perturbed by surrounding helium atoms. The pressure dependence of the emission wavelength suggests that the symmetry of helium atoms distributed around a thulium atom in the solid phase is similar to that in the liquid phase. The emission intensity was stable and large in the solid phase since thulium atoms were trapped at a density of 1010-1011 atoms/cm3. The lifetime of the excited state was measured to be 7.09+/-0.04 μs, which was longer than that of the 4f12(3H6)5d5/26s2 (6,5/2)7/2 state of free thulium atoms. The excited state is expected to be a mixed state of the 4f125d6s2 and 4f136s6p configurations. The metastable state 4f13(2Fo5/2)6s2 is populated by a radiative transition from this excited state and relaxes to the ground state through a magnetic dipole transition. The lifetime of the metastable state of a neutral thulium atom was measured to be 75+/-3 ms.

  18. Spectroscopy of Rb{sub 2} dimers in solid {sup 4}He

    SciTech Connect

    Moroshkin, P.; Hofer, A.; Ulzega, S.; Weis, A.

    2006-09-15

    We present experimental and theoretical studies of the absorption, emission, and photodissociation spectra of Rb{sub 2} molecules in solid helium. We have identified 11 absorption bands of Rb{sub 2}. All laser-excited molecular states are quenched by the interaction with the He matrix. The quenching results in efficient population of a metastable (1) {sup 3}{pi}{sub u} state, which emits fluorescence at 1042 nm. In order to explain the fluorescence at the forbidden transition and its time dependence we propose a new molecular exciplex Rb{sub 2}({sup 3}{pi}{sub u})He{sub 2}. We have also found evidence for the formation of diatomic bubble states following photodissociation of Rb{sub 2}.

  19. Final state effects in liquid /sup 4/He: An experimental test

    SciTech Connect

    Sokol, P.E.; Silver, R.N.; Sosnick, T.R.; Snow, W.M.

    1989-01-01

    Inelastic neutron scattering at high momentum transfers can provide direct information on the atomic momentum distribution n(p) when the Impulse Approximation (IA) is valid. In isotropic systems, the scattering in the IA is directly proportional to the longitudinal momentum distribution which is a function of a single scaling variable Y /triple bond/ (M/Q)(..omega.. /minus/ ..omega../sub r/), where M is the mass of the scatterer, Q is the momentum transfer, and ..omega../sub r/ = Q/sup 2//2M is the recoiled energy. However, the experimentally attainable Q's are not large enough to reach the IA limit. Deviations from the IA due to final state scattering by neighboring atoms, known as final state effects, will distort the observed scattering from the IA prediction. Thus, an understanding of deviations from the IA is essential to accurate determination of n(p). Liquid helium provides an excellent testing ground for studying FSE in a dense, strongly interacting system for two reasons. First, theoretical calculations of the momentum distributions are available in both the normal liquid, and superfluid phases. These calculations are believed to be quite accurate, since they agree well with several other measured properties of the liquid. In addition, n(p) in the superfluid exhibits a very sharp feature, the Bose condensate peak, which should be very sensitive to FSE. Comparison of the predicted scattering obtained from the theoretical n(p) using the IA to the experimentally observed scattering can be used to study deviations due to FSE. 14 refs., 7 figs.

  20. The ^3H(p,γ)^4He Reaction below 80 keV

    NASA Astrophysics Data System (ADS)

    Canon, R. S.; Kelley, J. H.; Nelson, S. O.; Schreiber, E. C.; Saburov, K.; Wulf, E. A.; Weller, H. R.; Prior, R. M.; Spraker, M.; Tilley, D. R.

    1999-10-01

    Significant advances in three body theory have resulted in excellent agreement with experimental radiative capture measurements(E. A. Wulf et al.), submitted to PRL. and emphasize the importance of MEC effects at energies below 100 keV(G. Schmid et al.), PRC 56, 2565 (1997).. Preliminary work has begun in applying these techniques to the four-body problem(A. Fonseca,W. Glöckle,A. Kievsky,H. Witala, (private communication).). In order to provide accurate experimental data for these forthcoming theoretical predictions, low energy polarized proton capture on tritium is being studied at TUNL. Preliminary results of these studies, which include a determination of the absolute cross section and measurements of the angular distributions of analyzing powers and cross sections, will be presented. Implications of these measurements will be discussed along with plans for future studies.

  1. Path-integral Monte Carlo simulation of the second layer of 4He adsorbed on graphite

    NASA Astrophysics Data System (ADS)

    Pierce, Marlon; Manousakis, Efstratios

    1999-02-01

    We have developed a path-integral Monte Carlo method for simulating helium films and apply it to the second layer of helium adsorbed on graphite. We use helium-helium and helium-graphite interactions that are found from potentials which realistically describe the interatomic interactions. The Monte Carlo sampling is over both particle positions and permutations of particle labels. From the particle configurations and static structure factor calculations, we find that this layer possesses, in order of increasing density, a superfluid liquid phase, a 7×7 commensurate solid phase that is registered with respect to the first layer, and an incommensurate solid phase. By applying the Maxwell construction to the dependence of the low-temperature total energy on the coverage, we are able to identify coexistence regions between the phases. From these, we deduce an effectively zero-temperature phase diagram. Our phase boundaries are in agreement with heat capacity and torsional oscillator measurements, and demonstrate that the experimentally observed disruption of the superfluid phase is caused by the growth of the commensurate phase. We further observe that the superfluid phase has a transition temperature consistent with the two-dimensional value. Promotion to the third layer occurs for densities above 0.212 atom/Å 2, in good agreement with experiment. Finally, we calculate the specific heat for each phase and obtain peaks at temperatures in general agreement with experiment.

  2. Laser ablation and spectroscopy of copper in liquid and solid {sup 4}He

    SciTech Connect

    Moroshkin, P.; Lebedev, V.; Weis, A.

    2011-11-15

    We present an experimental study of the laser-induced fluorescence spectra of Cu atoms in bulk liquid and solid helium matrices as well as in the dense plasma created by the laser ablation of copper in liquid helium. We observe transitions of the valence electron and of inner-shell electrons. The former produce structureless line shapes, a large broadening, and a blueshift. The latter practically are not shifted with respect to the free atom and possess a substructure consisting of a zero-phonon line and phonon wings. We suggest a qualitative interpretation of the observed spectra based on the atomic bubble model that takes the lifting of the |M{sub J}| degeneracy due to the bubble deformation and matrix-phonon interactions into account.

  3. A Common Optical Potential for 4He+12C at Intermediate Energies

    NASA Astrophysics Data System (ADS)

    Li-Yuan, Hu; Yu-Shou, Song; Ying-Wei, Hou; Hui-Lan, Liu

    2016-07-01

    Not Available Supported by the National Natural Science Foundation of China under Grant No 11205036, and the Fundamental Research Funds for the Central Universities of China under Grant No HEUCF101501.

  4. Direct Measurement of the 4He(12C, 16O)γ Total Cross Section Near Stellar Energies

    NASA Astrophysics Data System (ADS)

    Fujita, Kunihiro; Yamaguchi, Hiroyuki; Ban, Tadahiko; Hamamoto, Kenichi; Narikiyo, Yoshihiro; Tao, Nariaki; Sagara, Kenshi

    2015-05-01

    A cross section measurement employing a direct 16O detection method for the reaction energies from Ecm = 2.4 to 0.7 MeV is planned at Kyushu University Tandem Laboratory (KUTL). To perform this experiment and to obtain quantitative information about the cross section to within an error of 10%, we have developed several instruments, including a blow-in type windowless gas target, a recoil mass separator and a RF-deflector. The measurements at Ecm = 2.4 and 1.5 MeV have been performed with these instruments. For measuring at Ecm < 1.2 MeV, a hybrid detector employing both, an ionization chamber and a silicon detector was developed to reduce the carbon backgrounds more efficiently. The oxygen ions were clearly separated from carbon background by using the energy deposit in the ionization chamber. Experiment of Ecm = 1.2 MeV was performed and the cross section was obtained.

  5. Superfluid Reynolds number and the transition from potential flow to turbulence in superfluid 4He at millikelvin temperatures

    NASA Astrophysics Data System (ADS)

    Schoepe, W.

    2015-07-01

    This comment is on Phys. Rev. Lett. 144, 155302 (2015) by M.T. Reeves, T.P. Billam, B.P. Anderson, and A.S. Bradley "Identifying a superfluid Reynolds number via dynamical similarity" where a new superfluid Reynolds number is introduced. This definition is shown to be useful in the data analysis of the finite lifetime of turbulence observed with an oscillating sphere in superfluid helium at mK temperatures in a small velocity interval Δ v = ( v-v c ) just above the critical velocity v c . The very rapid increase in the lifetime with increasing superfluid Reynolds number is compared with the "supertransient" turbulence observed in classical pipe flow.

  6. Rate Coefficient for the (4)Heμ + CH4 Reaction at 500 K: Comparison between Theory and Experiment.

    PubMed

    Arseneau, Donald J; Fleming, Donald G; Li, Yongle; Li, Jun; Suleimanov, Yury V; Guo, Hua

    2016-03-01

    The rate constant for the H atom abstraction reaction from methane by the muonic helium atom, Heμ + CH4 → HeμH + CH3, is reported at 500 K and compared with theory, providing an important test of both the potential energy surface (PES) and reaction rate theory for the prototypical polyatomic CH5 reaction system. The theory used to characterize this reaction includes both variational transition-state (CVT/μOMT) theory (VTST) and ring polymer molecular dynamics (RPMD) calculations on a recently developed PES, which are compared as well with earlier calculations on different PESs for the H, D, and Mu + CH4 reactions, the latter, in particular, providing for a variation in atomic mass by a factor of 36. Though rigorous quantum calculations have been carried out for the H + CH4 reaction, these have not yet been extended to the isotopologues of this reaction (in contrast to H3), so it is important to provide tests of less rigorous theories in comparison with kinetic isotope effects measured by experiment. In this regard, the agreement between the VTST and RPMD calculations and experiment for the rate constant of the Heμ + CH4 reaction at 500 K is excellent, within 10% in both cases, which overlaps with experimental error.

  7. Theoretical study of differential charge-transfer cross sections for Ne4++He collisions at low energies

    NASA Astrophysics Data System (ADS)

    Tan, J.; Lin, C. D.

    1988-02-01

    A quantal two-channel calculation is applied to study charge-transfer differential cross sections in Ne4+ on He collisions at laboratory impact energies from 220 to 500 eV. The experimental data of Tunnell et al. were used to fit empirical potential curves and coupling terms from which the observed oscillatory structures in the differential cross sections were analyzed. In contrast with the double-charge-transfer process in C4+ on He, where the oscillations in the differential cross sections are attributed to pure Stueckelberg oscillations, we demonstrated that the differential cross sections for charge transfer in Ne4+ on He exhibit many fine fast oscillations and the observed structures are due to the envelopes of these unresolved fast oscillations. Classical deflection functions are used to help in interpreting the calculated oscillations.

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

    PubMed

    Lucchitta, Ivo

    2013-04-12

    Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) use thermochronometry to propose that the western paleo-Grand Canyon was nearly as deep 70 million years ago (Ma) as today. However, lithologies, facies relations, geomorphology, and paleotopography of Miocene interior-basin deposits near the mouth of the Grand Canyon show that no paleocanyon existed in that area during filling of the basin, ~17 to ~5 Ma. PMID:23580512

  9. A study of longitudinal charged-pion electroproduction in D, {sup 3}He, and {sup 4}He

    SciTech Connect

    Jackson, H.E.; Coulter, K.P.; Geesaman, D.F.

    1995-08-01

    Recent studies of pion electroproduction on the deuteron carried out by the ANL group at ALS, Saclay, show that even in the weakly-bound deuteron, multinucleon processes alter the electroproduction amplitudes in the forward direction. The data provide the first experimental indications for a significant change in the pion-nucleon coupling for nucleons bound in nuclei. It is clear that forward-angle electroproduction may be a sensitive probe of the properties of the pion coupling in the nuclear medium. At CEBAF, we will study longitudinal charged-pion electroproduction (in the excitation region below the delta isobar) along the direction of the momentum transfer where the charge scattering process dominates. Direct comparison of the cross section per nucleon in deuterium and the helium isotopes with the experimental value for the free nucleon will provide estimates of the strength of the nuclear pion field. A Rosenbluth separation of the longitudinal and transverse cross sections will be performed for four-momentum transfers of 2.5 and 10 fm{sup -2}. Measurements for a number of light nuclei will provide useful data on the sensitivity of longitudinal electroproduction to nuclear binding effects. If current conceptions of pion-exchange currents in nuclei are correct, longitudinal electroproduction will be suppressed at the lower momentum transfer and enhanced at the higher momentum transfer by multinucleon processes. If on the other hand, as suggested by recent data from Drell-Yan studies of antiquark structure functions, there is no such enhancement, a reformulation of pion exchange models of the medium- and short-range properties of nuclear forces will be required. Our proposal to carry out such a series of measurements at CEBAF using the coincident-pair spectrometer system planned for Hall C was approved. Pions will be observed in the short-orbit spectrometer (SOS) which will serve as the second arm.

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

    PubMed

    Karlstrom, Karl E; Lee, John; Kelley, Shari; Crow, Ryan; Young, Richard A; Lucchitta, Ivo; Beard, L Sue; Dorsey, Rebecca; Ricketts, Jason W; Dickinson, William R; Crossey, Laura

    2013-04-12

    Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) propose that the Grand Canyon is 70 million years old. Starkly contrasting models for the age of the Grand Canyon-70 versus 6 million years-can be reconciled by a shallow paleocanyon that was carved in the eastern Grand Canyon 25 to 15 million years ago (Ma), negating the proposed 70 Ma and 55 Ma paleocanyons. Cooling models and geologic data are most consistent with a 5 to 6 Ma age for western Grand Canyon and Marble Canyon.

  11. Comment on “Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon”

    NASA Astrophysics Data System (ADS)

    Karlstrom, Karl E.; Lee, John; Kelley, Shari; Crow, Ryan; Young, Richard A.; Lucchitta, Ivo; Beard, L. Sue; Dorsey, Rebecca; Ricketts, Jason W.; Dickinson, William R.; Crossey, Laura

    2013-04-01

    Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) propose that the Grand Canyon is 70 million years old. Starkly contrasting models for the age of the Grand Canyon—70 versus 6 million years—can be reconciled by a shallow paleocanyon that was carved in the eastern Grand Canyon 25 to 15 million years ago (Ma), negating the proposed 70 Ma and 55 Ma paleocanyons. Cooling models and geologic data are most consistent with a 5 to 6 Ma age for western Grand Canyon and Marble Canyon.

  12. Response to Comments on "Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon".

    PubMed

    Flowers, R M; Farley, K A

    2013-04-12

    We reiterate that geological observations do not require Grand Canyon carving coeval with Colorado River integration. (U-Th)/He data from the western canyon, totaling 29 reproducible analyses from six samples and two labs, compellingly support an ancient canyon. Three dispersed analyses from one anomalous sample do not refute this conclusion, nor do the claimed shortcomings of our modeling have validity.

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

    PubMed

    Lucchitta, Ivo

    2013-04-12

    Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) use thermochronometry to propose that the western paleo-Grand Canyon was nearly as deep 70 million years ago (Ma) as today. However, lithologies, facies relations, geomorphology, and paleotopography of Miocene interior-basin deposits near the mouth of the Grand Canyon show that no paleocanyon existed in that area during filling of the basin, ~17 to ~5 Ma.

  14. Comment on “Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon”

    NASA Astrophysics Data System (ADS)

    Lucchitta, Ivo

    2013-04-01

    Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) use thermochronometry to propose that the western paleo-Grand Canyon was nearly as deep 70 million years ago (Ma) as today. However, lithologies, facies relations, geomorphology, and paleotopography of Miocene interior-basin deposits near the mouth of the Grand Canyon show that no paleocanyon existed in that area during filling of the basin, ~17 to ~5 Ma.

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

    PubMed

    Karlstrom, Karl E; Lee, John; Kelley, Shari; Crow, Ryan; Young, Richard A; Lucchitta, Ivo; Beard, L Sue; Dorsey, Rebecca; Ricketts, Jason W; Dickinson, William R; Crossey, Laura

    2013-04-12

    Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) propose that the Grand Canyon is 70 million years old. Starkly contrasting models for the age of the Grand Canyon-70 versus 6 million years-can be reconciled by a shallow paleocanyon that was carved in the eastern Grand Canyon 25 to 15 million years ago (Ma), negating the proposed 70 Ma and 55 Ma paleocanyons. Cooling models and geologic data are most consistent with a 5 to 6 Ma age for western Grand Canyon and Marble Canyon. PMID:23589897

  16. Response to Comments on "Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon".

    PubMed

    Flowers, R M; Farley, K A

    2013-04-12

    We reiterate that geological observations do not require Grand Canyon carving coeval with Colorado River integration. (U-Th)/He data from the western canyon, totaling 29 reproducible analyses from six samples and two labs, compellingly support an ancient canyon. Three dispersed analyses from one anomalous sample do not refute this conclusion, nor do the claimed shortcomings of our modeling have validity. PMID:23580513

  17. Big-bang nucleosynthesis with a long-lived charged massive particle including {sup 4}He spallation processes in a bound state

    SciTech Connect

    Jittoh, Toshifumi; Kohri, Kazunori; Koike, Masafumi; Sato, Joe; Sugai, Kenichi; Yamanaka, Masato; Yazaki, Koichi

    2012-07-27

    We propose helium-4 spallation processes induced by long-lived stau in supersymmetric standard models, and investigate an impact of the processes on light elements abundances. We show that, as long as the phase space of helium-4 spallation processes is open, they are more important than stau-catalyzed fusion and hence constrain the stau property.

  18. Granitoid magmatism in the Arminskii block of Central Sikhote Alin (Primorye, Far Eastern Russia): U-Pb geochronology, 3He/4He isotopy, petrochemistry, and ore mineralization

    NASA Astrophysics Data System (ADS)

    Sakhno, V. G.; Kovalenko, S. V.; Lyzganov, A. V.

    2016-02-01

    This work presents the first isotope-geochronological data obtained for granitoid series of the Arminskii block of Central Sikhote Alin: Tatibi gabbromonzodiorite and Olgino leucocratic granite. Every series is characterized by a certain structural position and timing of the formation of ore mineralization. The Tatibi series is characterized by the presence of gold-ore occurrences including the potential Glukhoe goldore occurrence. Granitoids of the Olgino series comprise known tin-sulfide ore occurrences. The conditions for the generation of each series of rocks were revealed on the basis of geochronological-isotope data.

  19. Correlation of gold in siliceous sinters with {sup 3}He/{sup 4}He in hot spring waters of Yellowstone National Park

    SciTech Connect

    Fournier, R.O.; Thompson, J.M.; Kennedy, B.M.; Aoki, Masahiro

    1994-12-01

    Opaline sinter samples collected at Yellowstone National Park (YNP) were analyzed for gold by neutron activation and for other trace elements by the inductively coupled plasma optical emission spectroscopy (ICP-OES) method. No correlation was found between Au and As, Sb, or total Fe in the sinters, although the sample containing the highest Au also contains the highest Sb. There also was no correlation of Au in the sinter with the H{sub 2}S concentration in the discharged hot spring water or with the estimated temperature of last equilibration of the water with the surrounding rock. The Au in rhyolitic tuffs and lavas at YNP found within the Yellowstone caldera show the same range in Au as do those outside the caldera, while thermal waters from within this caldera all have been found to contain relatively low dissolved Au and to deposit sinters that contain relatively little Au. Therefore, it is not likely that variations in Au concentrations among these sinters simply reflect differences in leachable Au in the rocks through which the hydrothermal fluids have passed. Rather, variations in [H{sub 2}S], the concentration of total dissolved sulfide, that result from different physical and chemical processes that occur in different parts of the hydrothermal system appear to exert the main control on the abundance of Au in these sinters. Hydrothermal fluids at YNP convect upward through a series of successively shallower and cooler reservoirs where water-rock chemical and isotopic reactions occur in response to changing temperature and pressure. In some parts of the system the fluids undergo decompressional boiling, and in other parts they cool conductively without boiling. Mixing of ascending water from deep in the system with shallow groundwaters is common. All three processes generally result in a decrease in [H{sub 2}S] and destabilize dissolved gold bisulfide complexes in reservoir waters in the YNP system.

  20. Evaluation of the /sup 7/Li(n,n't)/sup 4/He cross section for ENDF/B-VI and application to uncertainty analysis

    SciTech Connect

    Young, P.G.; Davidson, J.W.; Muir, D.W.

    1988-01-01

    A new covariance analysis of n+/sup 7/Li cross section data has been completed for Version VI of ENDF/B. The analysis updates our 1981 work for ENDF/B-V.2 to include new data that has become available since that time and to incorporate cross correlations between different experiments. The bulk of the new measured data consists of some 10 new (or newly revised) tritium-production measurements involving about 70 new data points. The new analysis results in only small changes in the previous evaluation of the tritium-production cross section but significantly reduces the magnitudes of uncertainties due to the more extensive and accurate data base that was used. A two-dimensional sensitivity and uncertainty analysis of the Lithium Blanket Module experiments at the LOTUS facility was performed in order to assess the effects of the new /sup 7/Li cross sections on tritium breeding uncertainty in a realistic system. 4 refs., 6 figs., 3 tabs.

  1. Infrared rovibrational spectroscopy of OH–C{sub 2}H{sub 2} in {sup 4}He nanodroplets: Parity splitting due to partially quenched electronic angular momentum

    SciTech Connect

    Douberly, Gary E. Liang, Tao; Raston, Paul L.; Marshall, Mark D.

    2015-04-07

    The T-shaped OH–C{sub 2}H{sub 2} complex is formed in helium droplets via the sequential pick-up and solvation of the monomer fragments. Rovibrational spectra of the a-type OH stretch and b-type antisymmetric CH stretch vibrations contain resolved parity splitting that reveals the extent to which electronic angular momentum of the OH moiety is quenched upon complex formation. The energy difference between the spin-orbit coupled {sup 2}B{sub 1} (A″) and {sup 2}B{sub 2} (A′) electronic states is determined spectroscopically to be 216 cm{sup −1} in helium droplets, which is 13 cm{sup −1} larger than in the gas phase [Marshall et al., J. Chem. Phys. 121, 5845 (2004)]. The effect of the helium is rationalized as a difference in the solvation free energies of the two electronic states. This interpretation is motivated by the separation between the Q(3/2) and R(3/2) transitions in the infrared spectrum of the helium-solvated {sup 2}Π{sub 3/2} OH radical. Despite the expectation of a reduced rotational constant, the observed Q(3/2) to R(3/2) splitting is larger than in the gas phase by ≈0.3 cm{sup −1}. This observation can be accounted for quantitatively by assuming the energetic separation between {sup 2}Π{sub 3/2} and {sup 2}Π{sub 1/2} manifolds is increased by ≈40 cm{sup −1} upon helium solvation.

  2. Response to Comments on “Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon”

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    We reiterate that geological observations do not require Grand Canyon carving coeval with Colorado River integration. (U-Th)/He data from the western canyon, totaling 29 reproducible analyses from six samples and two labs, compellingly support an ancient canyon. Three dispersed analyses from one anomalous sample do not refute this conclusion, nor do the claimed shortcomings of our modeling have validity.

  3. Temperature Measurements of Fusion Plasmas Produced by Petawatt-Laser-Irradiated D2-He3 or CD4-He3 Clustering Gases

    NASA Astrophysics Data System (ADS)

    Bang, W.; Barbui, M.; Bonasera, A.; Dyer, G.; Quevedo, H. J.; Hagel, K.; Schmidt, K.; Consoli, F.; De Angelis, R.; Andreoli, P.; Gaul, E.; Bernstein, A. C.; Donovan, M.; Barbarino, M.; Kimura, S.; Mazzocco, M.; Sura, J.; Natowitz, J. B.; Ditmire, T.

    2013-08-01

    Two different methods have been employed to determine the plasma temperature in a laser-cluster fusion experiment on the Texas Petawatt laser. In the first, the temperature was derived from time-of-flight data of deuterium ions ejected from exploding D2 or CD4 clusters. In the second, the temperature was measured from the ratio of the rates of two different nuclear fusion reactions occurring in the plasma at the same time: D(d,He3)n and He3(d,p)He4. The temperatures determined by these two methods agree well, which indicates that (i) the ion energy distribution is not significantly distorted when ions travel in the disassembling plasma; (ii) the kinetic energy of deuterium ions, especially the “hottest part” responsible for nuclear fusion, is well described by a near-Maxwellian distribution.

  4. The influence of Kapitza resistance on the establishment of stationary non-equilibrium states in superfluid 3He-4He solutions

    NASA Astrophysics Data System (ADS)

    Vihtinskaya, T. G.; Nemchenko, K. E.; Rogova, S. Yu.

    2016-08-01

    We examine the establishment of stationary non-equilibrium states when a flow of heat is turned on in superfluid solutions with a sufficiently high (9.8%) concentration of 3He. We study the influence of possible relaxation mechanisms, focusing on the Kapitza jump in particular, on the process of establishing a constant temperature gradient. We found the thermal diffusivity, thermal conductivity and the Kapitza coefficients by comparing the theoretical calculations against experimental data. It is shown that it is necessary to include the Kapitza jump in order to perform a quantitative description of the experimental data.

  5. Distortion of bulk-ion distribution function due to nuclear elastic scattering and its effect on T(d,n){sup 4}He reaction rate coefficient in neutral-beam-injected deuterium-tritium plasmas

    SciTech Connect

    Matsuura, H.; Nakao, Y.

    2007-05-15

    An effect of nuclear elastic scattering on the rate coefficient of fusion reaction between field deuteron and triton in the presence of neutral beam injection heating is studied. Without assuming a Maxwellian for bulk-ion distribution function, the Boltzmann-Fokker-Planck (BFP) equations for field (bulk) deuteron, field (bulk) triton, {alpha}-particle, and beam deuteron are simultaneously solved in an ITER-like deuterium-tritium thermonuclear plasma [R. Aymar, Fusion Eng. Des. 55, 107 (2001)]. The BFP calculation shows that enhancement of the reaction rate coefficient due to knock-on tail formation in fuel-ion distribution functions becomes appreciable, especially in the case of low-density operations.

  6. Response to “Comment on ‘Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation”’ [Phys. Fluids 26, 019101 (2014)

    SciTech Connect

    Van Gorder, Robert A.

    2014-01-15

    I agree with the authors regarding their comments on the Donnelly-Glaberson instability for such helical filaments as those obtained in my paper. I also find merit in their derivation of the quantum LIA (local induction approximation) in the manner of the LIA of Boffetta et al. However, I disagree with the primary criticisms of Hietala and Hänninen. In particular, though they suggest LIA and local nonlinear equation modes are not comparable since the former class of models contains superfluid friction parameters, note that since these parameters are small one may take them to zero and consider a qualitative comparison of the models (which is what was done in my paper). Second, while Hietala and Hänninen criticize certain assumptions made in my paper (and the paper of Shivamoggi where the model comes from) since the results break-down when Ak → ∞, note that in my paper I state that any deviations from the central axis along which the filament is aligned must be sufficiently bounded in variation. Therefore, it was already acknowledged that Ak(=|Φ{sub x}|) should be sufficiently bounded, precluding the Ak → ∞ case. I also show that, despite what Hietala and Hänninen claim, the dispersion relation obtained in my paper is consistent with LIA, where applicable. Finally, while Hietala and Hänninen claim that the dispersion parameter should be complex valued, I show that their dispersion relation is wrong, since it was derived incorrectly (they assume the complex modulus of the potential function is constant, yet then use this to obtain a potential function with non-constant modulus)

  7. Generation of polarized 4He ion beam by optical pumping using circularly and linearly polarized radiation tuned to D0 line (He metastables 2S1→2P0)

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Yamauchi, Y.

    2007-06-01

    It is demonstrated that simultaneous optical pumping (OP) by circularly and linearly polarized 1083 nm radiation tuned to the D0 line (He metastables 23S1→23P0 transition) substantially improves the polarization of the He+ ion beam, compared with conventional OP by the circularly polarized D1 ( 23S1→23P1) or D2 ( 23S1→23P2) line.

  8. Radiogenic helium in shallow groundwater within a clay till, southwestern Ontario

    USGS Publications Warehouse

    Sheldon, A.L.; Solomon, D.K.; Poreda, R.J.; Hunt, A.

    2003-01-01

    Profiles of 4He in pore water were measured in clay aquitards in SW Ontario. The 4He distributions are consistent with groundwater velocities that are 70% of initial 4He for 50 to 60 kA prior to incorporation into the till.

  9. Thermal hysteresis of the thermal conductivity in isotopically impure bcc 3He

    NASA Astrophysics Data System (ADS)

    Greenberg, A. S.; Armstrong, G.

    1980-11-01

    We have measured the thermal conductivity of bcc 3He containing 10 and 500 ppm 4He for temperatures below the isotopic phase separation. We find the conductivity measured during cooling can be significantly greater, as much as an order of magnitude, than upon warming. This hysteresis depends strongly on the molar volume and 4He concentration. We interpret our results in terms of phonon scattering from the boundary of solid 4He clusters formed by quantum diffusion and nucleated by crystalline faults.

  10. Effect of the neutron lifetime on processes in the early universe

    NASA Astrophysics Data System (ADS)

    Chechkin, A. V.; Ivanchik, A. V.; Serebrov, A. P.; Bobashev, S. V.

    2016-07-01

    The influence of the neutron lifetime on the abundance of light elements produced during the primordial nucleosynthesis early in the birth of the Universe is considered. Among light elements, namely, D, 3He, 4He, and 7Li, 4He proves to be most sensitive to neutron lifetime τ n . Astronomic data on the light element abundance also provide the best accuracy for 4He. The solution of a number of problems discussed in this paper requires improving the accuracy of observations for the 4He abundance and refining the value of τ n .

  11. Fission fragment driven neutron source

    DOEpatents

    Miller, Lowell G.; Young, Robert C.; Brugger, Robert M.

    1976-01-01

    Fissionable uranium formed into a foil is bombarded with thermal neutrons in the presence of deuterium-tritium gas. The resulting fission fragments impart energy to accelerate deuterium and tritium particles which in turn provide approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He.

  12. Nuclear and partonic dynamics in high energy elastic nucleus-nucleus scattering

    SciTech Connect

    Malecki, A. )

    1991-10-01

    A hybrid description of diffraction which combines a geometrical modeling of multiple scattering with many-channel effects resulting from intrinsic dynamics on the nuclear and subnuclear level is presented. The application to {sup 4}He-{sup 4}He elastic scattering is satisfactory. Our analysis suggests that, at large momentum transfers, the parton constituents of nucleons immersed in nuclei are deconfined.

  13. Can particle beam therapy be improved using helium ions? - a planning study focusing on pediatric patients.

    PubMed

    Knäusl, Barbara; Fuchs, Hermann; Dieckmann, Karin; Georg, Dietmar

    2016-06-01

    Aim To explore the potential of scanned helium ion beam therapy ((4)He) compared to proton therapy in a comparative planning study focusing on pediatric patients. This was motivated by the superior biological and physical characteristics of (4)He. Material and methods For eleven neuroblastoma (NB), nine Hodgkin lymphoma (HL), five Wilms tumor (WT), five ependymoma (EP) and four Ewing sarcoma (EW) patients, treatment plans were created for protons and (4)He. Dose prescription to the planning target volume (PTV) was 21 Gy [relative biological effectiveness (RBE)] (NB), 19.8 Gy (RBE) (HL), 25.2 Gy (RBE) for the WT boost volume and 54 Gy (RBE) for EP and EW patients. A pencil beam algorithm for protons (constant RBE = 1.1) and (4)He was implemented in the treatment planning system Hyperion. For (4)He the relative biological effectiveness (RBE) was calculated with a 'zonal' model based on different linear energy transfer regions. Results Target constraints were fulfilled for all indications. For NB patients differences for kidneys and liver were observed for all dose-volume areas, except the high-dose volume. The body volume receiving up to 12.6 Gy (RBE) was reduced by up to 10% with (4)He. For WT patients the mean and high-dose volume for the liver was improved when using (4)He. For EP normal tissue dose was reduced using (4)He with 12.7% of the voxels receiving higher doses using protons. For HL and EW sarcoma patients the combination of large PTV volumes with the position of the organs at risk (OARs) obliterated the differences between the two particle species, while patients with the heart close to the PTV could benefit from (4)He. Conclusion Treatment plan quality improved with (4)He compared to proton plans, but advantages in OAR sparing were depending on indication and tumor geometries. These first results of scanned (4)He therapy motivate comprehensive research on (4)He, including acquisition of experimental data to improve modeling of (4)He. PMID

  14. Antimatter regions in the early universe and big bang nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Kurki-Suonio, Hannu; Sihvola, Elina

    2000-11-01

    We have studied big bang nucleosynthesis in the presence of regions of antimatter. Depending on the distance scale of the antimatter region, and thus the epoch of their annihilation, the amount of antimatter in the early universe is constrained by the observed abundances. Small regions, which annihilate after weak freezeout but before nucleosynthesis, lead to a reduction in the 4He yield, because of neutron annihilation. Large regions, which annihilate after nucleosynthesis, lead to an increased 3He yield. Deuterium production is also affected but not as much. The three most important production mechanisms of 3He are (1) photodisintegration of 4He by the annihilation radiation, (2) p¯4He annihilation, and (3) n¯4He annihilation by ``secondary'' antineutrons produced in 4He¯ annihilation. Although p¯4He annihilation produces more 3He than the secondary n¯4He annihilation, the products of the latter survive later annihilation much better, since they are distributed further away from the annihilation zone. Our results are in qualitative agreement with similar work by Rehm and Jedamzik, but we get a larger 3He yield.

  15. Acoustic Resonances in Helium Fluids Excited by Quartz Tuning Forks

    NASA Astrophysics Data System (ADS)

    Salmela, A.; Tuoriniemi, J.; Rysti, J.

    2011-03-01

    Ordinary quartz tuning fork resonators, operated at about 30 or 200 kHz frequency, couple to acoustic first and second sound resonances in helium fluids under certain conditions. We have studied acoustic resonances in supercritical 4He, normal and superfluid 4He, and in isotopic mixtures of helium. Suggestive temperature, pressure, and concentration dependences are given. Furthermore, we propose a thermometric reference point device based on second sound resonances in helium mixtures, and indicate possible differences in the nature of second sound resonances in superfluid 4He and helium mixtures.

  16. Impulsive 3He-rich Solar Energetic Particle Events detected with EPHIN

    NASA Astrophysics Data System (ADS)

    Rodriguez-Frias, M. D.; Gomez-Herrero, R.; del Peral, L.; Sequeiros, J.; Kunow, H.; Mueller-Mellin, R.

    2001-08-01

    We report observation of 3 He-rich solar energetic particles (SEP) events detected by Electron Proton and Helium Instrument (EPHIN) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft. EPHIN has been detecting Helium isotopes in the energy range 4-53 MeV/n since December 1995 using a ˜E-E sensor system with solid-state detectors. In this paper we concentrate on observations of SEP with excess in the 3 He abundance. The abundances 3 He/4 He and 4 He/1 H have been obtained and compared among different events. Energy spectra of protons, 3 He, 4 He have been studied.

  17. Constraining antimatter domains in the early universe with big bang nucleosynthesis.

    PubMed

    Kurki-Suonio, H; Sihvola, E

    2000-04-24

    We consider the effect of a small-scale matter-antimatter domain structure on big bang nucleosynthesis and place upper limits on the amount of antimatter in the early universe. For small domains, which annihilate before nucleosynthesis, this limit comes from underproduction of 4He. For larger domains, the limit comes from 3He overproduction. Since most of the 3He from &pmacr; 4He annihilation are themselves annihilated, the main source of primordial 3He is the photodisintegration of 4He by the electromagnetic cascades initiated by the annihilation.

  18. Cold fusion, Alchemist's dream

    SciTech Connect

    Clayton, E.D.

    1989-09-01

    In this report the following topics relating to cold fusion are discussed: muon catalysed cold fusion; piezonuclear fusion; sundry explanations pertaining to cold fusion; cosmic ray muon catalysed cold fusion; vibrational mechanisms in excited states of D{sub 2} molecules; barrier penetration probabilities within the hydrogenated metal lattice/piezonuclear fusion; branching ratios of D{sub 2} fusion at low energies; fusion of deuterons into {sup 4}He; secondary D+T fusion within the hydrogenated metal lattice; {sup 3}He to {sup 4}He ratio within the metal lattice; shock induced fusion; and anomalously high isotopic ratios of {sup 3}He/{sup 4}He.

  19. Superfluid thermodynamic cycle refrigerator

    DOEpatents

    Swift, Gregory W.; Kotsubo, Vincent Y.

    1992-01-01

    A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.

  20. Superfluid thermodynamic cycle refrigerator

    DOEpatents

    Swift, G.W.; Kotsubo, V.Y.

    1992-12-22

    A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of [sup 3]He in a single phase [sup 3]He-[sup 4]He solution. The [sup 3]He in superfluid [sup 4]He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid [sup 3]He at an initial concentration in superfluid [sup 4]He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of [sup 4]He while restricting passage of [sup 3]He. The [sup 3]He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K. 12 figs.

  1. Large electron screening effect in different environments

    SciTech Connect

    Cvetinović, Aleksandra Lipoglavšek, Matej; Markelj, Sabina; Vesić, Jelena

    2015-10-15

    Electron screening effect was studied in the {sup 1}H({sup 7}Li,α){sup 4}He, {sup 1}H({sup 11}B,α){sup 4}He and {sup 1}H({sup 19}F,αγ){sup 16}O reactions in inverse kinematics on different hydrogen implanted targets. Results show large electron screening potentials strongly dependent on the proton number Z of the projectile.

  2. Electroproduction of strangeness on (Lambda)H-3,4 bound states on helium

    SciTech Connect

    F. Dohrmann; D. Abbott; A. Ahmidouch; P. Ambrozewicz; C. S. Armstrong; J. Arrington; R. Asaturyan; K. Assamagan; S. Avery; K. Bailey; S. Beedoe; H. Bitao; H. Breuer; D. S. Brown; R. Carlini; J. Cha; N. Chant; E. Christy; A. Cochran; L. Cole; G. Collins; C. Cothran; J. Crowder; W. J. Cummings; S. Danagoulian; F. Duncan; J. Dunne; D. Dutta; T. Eden; M. Elaasar; R. Ent; L. Ewell; H. Fenker; H. T. Fortune; Y. Fujii; L. Gan; H. Gao; K. Garrow; D. F. Geesaman; P. Gueye; K. Gustafsson; K. Hafidi; J. O. Hansen; W. Hinton; H. E. Jackson; H. Juengst; C. Keppel; A. Klein; D. Koltenuk; Y. Liang; J. H. Liu; A. Lung; D. Mack; R. Madey; P. Markowitz; C. J. Martoff; D. Meekins; J. Mitchell; T. Miyoshi; H. Mkrtchyan; R. Mohring; S. K. Mtingwa; B. Mueller; T. G. O'Neill; G. Niculescu; I. Niculescu; D. Potterveld; J. W. Price; B. A. Raue; P. E. Reimer; J. Reinhold; J. Roche; P. Roos; M. Sarsour; Y. Sato; G. Savage; R. Sawafta; R. E. Segel; A. Yu. Semenov; S. Stepanyan; V. Tadevosian; S. Tajima; L. Tang; B. Terburg; A. Uzzle; S. Wood; H. Yamaguchi; C. Yan; C. Yan; L. Yuan; M. Zeier; B. Zeidman; B. Zihlmann

    2005-05-01

    The A(e,eK+)X reaction has been investigated at Jefferson Laboratory. Data were taken for Q{sup 2} approx. 0.35 GeV{sup 2} at a beam energy of 3.245 GeV for 1H,3He and 4He targets. Evidence for Lambda-hypernuclear bound states is seen for 3,4He targets. This is the first time that the electroproduction of these hypernuclei has been observed.

  3. Electroproduction of strangeness on {sub {lambda}}{sup 3,4}H bound states on Helium

    SciTech Connect

    Dohrmann, F.; Abbott, D.; Carlini, R.; Dunne, J.; Ent, R.; Fenker, H.; Garrow, K.; Lung, A.; Mack, D.; Meekins, D.; Mitchell, J.; Wood, S.; Yan, C.; Ahmidouch, A.; Ambrozewicz, P.; Martoff, C.J.; Armstrong, C.S.; Arrington, J.; Bailey, K.; Cummings, W.J.

    2005-05-06

    The A(e,e'K+)X reaction has been investigated at Jefferson Laboratory. Data were taken for Q2 {approx_equal} 0.35 GeV2 at a beam energy of 3.245 GeV for 1H,3He and 4He targets. Evidence for {lambda}-hypernuclear bound states is seen for 3,4He targets. This is the first time that the electroproduction of these hypernuclei has been observed.

  4. Korteweg-deVries solitons and helium films

    SciTech Connect

    Condat, C.A.; Guyer, R.A.

    1982-03-01

    The possibility of propagating Korteweg-deVries solitons in a superfluid /sup 4/He film and in a superfluid /sup 4/He films overlayed by a /sup 3/He film is discussed. Various dispersive and nonlinear contribution tot he equation for the nonlinear modes of the films are analyzed. Conditions depending on the thickness of the films are obtained for the propagation of troughlike and bumplike solitons.

  5. Episodic entrainment of deep primordial mantle material into ocean island basalts.

    PubMed

    Williams, Curtis D; Li, Mingming; McNamara, Allen K; Garnero, Edward J; van Soest, Matthijs C

    2015-11-24

    Chemical differences between mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) provide critical evidence that the Earth's mantle is compositionally heterogeneous. MORBs generally exhibit a relatively low and narrow range of (3)He/(4)He ratios on a global scale, whereas OIBs display larger variability in both time and space. The primordial origin of (3)He in OIBs has motivated hypotheses that high (3)He/(4)He ratios are the product of mantle plumes sampling chemically distinct material, but do not account for lower MORB-like (3)He/(4)He ratios in OIBs, nor their observed spatial and temporal variability. Here we perform thermochemical convection calculations which show the variable (3)He/(4)He signature of OIBs can be reproduced by deep isolated mantle reservoirs of primordial material that are viscously entrained by thermal plumes. Entrainment is highly time-dependent, producing a wide range of (3)He/(4)He ratios similar to that observed in OIBs worldwide and indicate MORB-like (3)He/(4)He ratios in OIBs cannot be used to preclude deep mantle-sourced hotspots.

  6. Effect of breakup and transfer on complete and incomplete fusion in 6Li+209Bi reaction in multi-body classical molecular dynamics calculation

    NASA Astrophysics Data System (ADS)

    Morker, Mitul R.; Godre, Subodh S.

    2016-05-01

    The effect of breakup and transfer in 6Li+209Bi reaction is studied in a multi-body classical molecular dynamics approach in which the weakly-bound projectile 6Li is constructed as a 2-body cluster of 4He and 2H in a configuration corresponding to the observed breakup energy. This 3-body system with their individual nucleon configuration in their ground state is dynamically evolved with given initial conditions using Classical Rigid Body Dynamics (CRBD) approach up to distances close to the barrier when the rigid-body constraint on the target, inter-fragment distance, and 2H itself are relaxed, allowing for possible breakup of 2H which may result in incomplete fusion following the transfer of the n or p. Relative probabilities of the possible events such as scattering with and without breakup, DCF, SCF, ICF(x) where x may be 4He, 2H, 4He+n, 4He+p, n, p are calculated. Comparison of the calculated event-probabilities, complete, and incomplete fusion cross sections with the calculation in which 2H is kept rigid demonstrates the effect of the transfer reactions on complete and incomplete fusion in the 4-body reaction. Events ICF(4He+n) corresponding to nstripping followed by breakup of the resultant 5Li to 4He+p are found to contribute significantly in the fusion process in agreement with a recent experimental observation of direct reaction processes in breakup of weakly-bound projectiles.

  7. High-temperature supersolid of He4 in a one-dimensional periodic potential

    DOE PAGESBeta

    Olsen, Raina J.

    2015-03-02

    The search for robust experimental proof of supersolidity has encountered many complicating factors, such as temperature dependent changes in the mechanical properties of solid 4He which mimic the signature of superfluid flow. As a result, the physical existence and true nature of this unique state of matter are still under debate. Here we consider 4He stabilized by a one-dimensional periodic potential whose lattice spacing is similar to the length scale of the 4He-4He interaction. We use the Bogoliubov transformation to calculate the excitation spectrum, finding that when interactions between nearest or next-nearest neighbors are attractive, there is a finite positivemore » gap in energy between the delocalized ground state and the lowest energy excitations which, under certain conditions, is significantly larger than both the melting temperature and the lambda temperature. This means that it should be possible to observe a supersolid at a high enough temperature that superfluidity in bulk liquid 4He or changes in the mechanical properties of bulk solid 4He do not obscure it. Lastly, we also discuss the properties of experimentally achievable materials which could support this type of supersolid.« less

  8. Helium and lead isotopes reveal the geochemical geometry of the Samoan plume.

    PubMed

    Jackson, M G; Hart, S R; Konter, J G; Kurz, M D; Blusztajn, J; Farley, K A

    2014-10-16

    Hotspot lavas erupted at ocean islands exhibit tremendous isotopic variability, indicating that there are numerous mantle components hosted in upwelling mantle plumes that generate volcanism at hotspots like Hawaii and Samoa. However, it is not known how the surface expression of the various geochemical components observed in hotspot volcanoes relates to their spatial distribution within the plume. Here we present a relationship between He and Pb isotopes in Samoan lavas that places severe constraints on the distribution of geochemical species within the plume. The Pb-isotopic compositions of the Samoan lavas reveal several distinct geochemical groups, each corresponding to a different geographic lineament of volcanoes. Each group has a signature associated with one of four mantle endmembers with low (3)He/(4)He: EMII (enriched mantle 2), EMI (enriched mantle 1), HIMU (high µ = (238)U/(204)Pb) and DM (depleted mantle). Critically, these four geochemical groups trend towards a common region of Pb-isotopic space with high (3)He/(4)He. This observation is consistent with several low-(3)He/(4)He components in the plume mixing with a common high-(3)He/(4)He component, but not mixing much with each other. The mixing relationships inferred from the new He and Pb isotopic data provide the clearest picture yet of the geochemical geometry of a mantle plume, and are best explained by a high-(3)He/(4)He plume matrix that hosts, and mixes with, several distinct low-(3)He/(4)He components. PMID:25318524

  9. Episodic entrainment of deep primordial mantle material into ocean island basalts.

    PubMed

    Williams, Curtis D; Li, Mingming; McNamara, Allen K; Garnero, Edward J; van Soest, Matthijs C

    2015-01-01

    Chemical differences between mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) provide critical evidence that the Earth's mantle is compositionally heterogeneous. MORBs generally exhibit a relatively low and narrow range of (3)He/(4)He ratios on a global scale, whereas OIBs display larger variability in both time and space. The primordial origin of (3)He in OIBs has motivated hypotheses that high (3)He/(4)He ratios are the product of mantle plumes sampling chemically distinct material, but do not account for lower MORB-like (3)He/(4)He ratios in OIBs, nor their observed spatial and temporal variability. Here we perform thermochemical convection calculations which show the variable (3)He/(4)He signature of OIBs can be reproduced by deep isolated mantle reservoirs of primordial material that are viscously entrained by thermal plumes. Entrainment is highly time-dependent, producing a wide range of (3)He/(4)He ratios similar to that observed in OIBs worldwide and indicate MORB-like (3)He/(4)He ratios in OIBs cannot be used to preclude deep mantle-sourced hotspots. PMID:26596781

  10. Results of the determination of He in cenozoic aquifers using the GC method.

    PubMed

    Kotowski, Tomasz; Najman, Joanna

    2015-04-01

    Applications of the Helium (He) method known so far consisted mainly of 4He measurements using a special mass spectrometer. 4He measurements for groundwater dating purposes can be replaced by total He (3He+4He) concentration measurements because the content of 3He can be ignored. The concentrations of 3He are very low and 3He/4 He ratios do not exceed 1.0·10(-5) in most cases. In this study, the total He concentrations in groundwater were determined using the gas chromatographic (GC) method as an alternative to methods based on spectrometry measurement. He concentrations in groundwater were used for the determination of residence time and groundwater circulation. Additionally, the radiocarbon method was used to determine the value of the external He flux (JHe) in the study area. Obtained low He concentrations and their small variation within the ca. 65 km long section along which groundwater flows indicate that it is likely there is relatively short residence time and a strong hydraulic connection between the aquifers. The estimated residence time (ca. 3000 years) is heavily dependent on the great uncertainty of the He concentration resulting from the low concentrations of He, the external 4He flux value adopted for calculation purposes and the 14C ages used to estimate the external 4He flux.

  11. Helium and lead isotopes reveal the geochemical geometry of the Samoan plume.

    PubMed

    Jackson, M G; Hart, S R; Konter, J G; Kurz, M D; Blusztajn, J; Farley, K A

    2014-10-16

    Hotspot lavas erupted at ocean islands exhibit tremendous isotopic variability, indicating that there are numerous mantle components hosted in upwelling mantle plumes that generate volcanism at hotspots like Hawaii and Samoa. However, it is not known how the surface expression of the various geochemical components observed in hotspot volcanoes relates to their spatial distribution within the plume. Here we present a relationship between He and Pb isotopes in Samoan lavas that places severe constraints on the distribution of geochemical species within the plume. The Pb-isotopic compositions of the Samoan lavas reveal several distinct geochemical groups, each corresponding to a different geographic lineament of volcanoes. Each group has a signature associated with one of four mantle endmembers with low (3)He/(4)He: EMII (enriched mantle 2), EMI (enriched mantle 1), HIMU (high µ = (238)U/(204)Pb) and DM (depleted mantle). Critically, these four geochemical groups trend towards a common region of Pb-isotopic space with high (3)He/(4)He. This observation is consistent with several low-(3)He/(4)He components in the plume mixing with a common high-(3)He/(4)He component, but not mixing much with each other. The mixing relationships inferred from the new He and Pb isotopic data provide the clearest picture yet of the geochemical geometry of a mantle plume, and are best explained by a high-(3)He/(4)He plume matrix that hosts, and mixes with, several distinct low-(3)He/(4)He components.

  12. Episodic entrainment of deep primordial mantle material into ocean island basalts

    PubMed Central

    Williams, Curtis D.; Li, Mingming; McNamara, Allen K.; Garnero, Edward J.; van Soest, Matthijs C.

    2015-01-01

    Chemical differences between mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) provide critical evidence that the Earth's mantle is compositionally heterogeneous. MORBs generally exhibit a relatively low and narrow range of 3He/4He ratios on a global scale, whereas OIBs display larger variability in both time and space. The primordial origin of 3He in OIBs has motivated hypotheses that high 3He/4He ratios are the product of mantle plumes sampling chemically distinct material, but do not account for lower MORB-like 3He/4He ratios in OIBs, nor their observed spatial and temporal variability. Here we perform thermochemical convection calculations which show the variable 3He/4He signature of OIBs can be reproduced by deep isolated mantle reservoirs of primordial material that are viscously entrained by thermal plumes. Entrainment is highly time-dependent, producing a wide range of 3He/4He ratios similar to that observed in OIBs worldwide and indicate MORB-like 3He/4He ratios in OIBs cannot be used to preclude deep mantle-sourced hotspots. PMID:26596781

  13. Peridotite vs pyroxenite source lithologies of primordial helium in the Iceland and Hawaiian plumes

    NASA Astrophysics Data System (ADS)

    Weiss, Y.; Class, C.; Goldstein, S. L.; Hofmann, A. W.; Sobolev, A. V.

    2014-12-01

    Recent studies have suggested that chemical compositions of olivine phenocrysts can be used to distinguish between olivine-rich and olivine-poor lithologies (peridotite and pyroxenite) in the mantle sources of MORB and OIB (Sobolev et al, 2005, 2007, Herzberg, 2011). Olivine phenocrysts are also used for 3He/4He analyses, allowing us to address linkages between basalt source lithologies and primordial helium storage in the mantle. We report 3He/4He analyses of olivine phenocrysts from Iceland and Hawaii that were previously analyzed for major and minor elements (Sobolev et al., 2007, 2008). 3He/4He in Iceland samples vary between 7-26 (R/RA) and correlate negatively with Mn/Fe and positively with Ni/Mg of the olivine phenocrysts, as well as 187Os/188Os and Gd/Lu in host lavas. These relationships suggest mixing between a degassed and incompatible element depleted peridotitic source (MORB-type?), and a primordial 3He enriched plume source containing lithologies with lower modal olivine/garnet (pyroxenite?). Hawaiian samples, on the other hand, form a positive trend in 3He/4He vs Mn/Fe space, as compared to the negative trend of the Iceland samples. Thus, the Iceland and Hawaiian plumes give contrasting results for the high 3He/4He host lithology - more pyroxenite-rich for Iceland and peridotite-rich for Hawaii. Plotting the Iceland and Hawaiian plume data together for 3He/4He vs Mn/Fe, the two divergent trends intersect at the composition of Loihi, characterized by intermediate pyroxenite/peridotite and 3He/4He of 9-28 RA. Baffin Island and West Greenland picrites have the highest known magmatic 3He/4He and high olivine Mn/Fe (Starkey et al., 2009, 2012), indicating high 3He/4He peridotites as well as pyroxenites in the Iceland plume. When plotted with the Iceland-Hawaii samples, they lie on an extension of the Hawaiian trend. This raises the possibility (pending more data from other plumes) that there is a global trend showing high 3He/4He residing in peridotite.

  14. Primary and secondary processes constraining the noble gas isotopic signatures of carbonatites and silicate rocks from Brava Island: evidence for a lower mantle origin of the Cape Verde plume

    NASA Astrophysics Data System (ADS)

    Mourão, Cyntia; Moreira, Manuel; Mata, João; Raquin, Aude; Madeira, José

    2012-06-01

    We present and discuss noble gas compositions of minerals from silicate rocks (olivines) and carbonatites (apatites and calcites) from Brava Island. The presence of an almost ubiquitous atmosphere-derived fingerprint is explained as reflecting contamination by seawater. Because of the high U and Th content in apatites, which are responsible for 4He production by α-decay, the high measured 4He/3He ratios do not represent magmatic signatures. In contrast, low values of 4He/3He in calcites (≥61,223; R/ R a ≤ 11.80) and olivines (≥56,240; R/ R a ≤ 12.85) are considered to be representative of signatures trapped at the time of crystallization, given that there are no evidences for significant cosmogenic additions. These relatively low 4He/3He ratios depicted by silicate and carbonatite rocks imply the contribution of a reservoir that evolved under low (U + Th)/3He; this is considered a strong evidence for the genesis of Brava by a mantle plume deeply anchored in the lower mantle. The inferred low 4He/40Ar* ratio (≈0.3), before degassing, is thought to reflect the contribution to the carbonatites source of a mantle domain evolving under high K/U, which cannot be explained by recycling of crustal components. The possible link between the low 4He/40Ar* source and the "missing Ar reservoir" is discussed. The usually referred geochemical dichotomy between Northern and Southern Cape Verde islands, which is markedly evident from Sr, Nd, and Pb isotope signatures, is not apparent from Brava Island (Southern Cape Verde), where some samples present relatively unradiogenic 4He/3He signatures, similar to those reported for the Northern islands of the archipelago.

  15. Helium isotope geochemistry of some volcanic rocks from Saint Helena

    NASA Astrophysics Data System (ADS)

    Graham, David W.; Humphris, Susan E.; Jenkins, William J.; Kurz, Mark D.

    1992-05-01

    3He/ 4He ratios have been measured for olivine and clinopyroxene phenocrysts in 7-15 m.y. old basaltic lavas from the island of St. Helena. Magmatic helium was effectively resolved from post-eruptive radiogenic helium by employing various extraction techniques, including in vacuo crushing, and stepwise heating or fusion of the powders following crushing. The inherited 3He/ 4He ratio at St. Helena is 4.3-5.9 R A. Helium isotope disequilibrium is present within the phenocrysts, with lower 3He/ 4He upon heating and fusion of the powders following crushing, due to radiogenic ingrowth or to α-particle implantation from the surrounding (U + Th)-rich lavas. A single crushing analysis for clinopyroxene in a basalt from Tubuaii gave 3He/ 4He= 7.1 R A. 3He/ 4He ratios at St. Helena and Tubuaii (HIMU hotspots characterized by radiogenic Pb isotope signatures) are similar to 3He/ 4He ratios previously measured at Tristan da Cunha and Gough Island (EM hotspots characterized by low 206Pb/ 204Pb ). Overall, the He sbnd Sr sbnd Pb isotope systematics at these islands are consistent with a mantle origin as contiguous, heterogeneous materials, such as recycled crust and/or lithosphere. 3He/ 4He ratios at HIMU hotspots are similar to mantle xenoliths which display nearly the entire range of Pb isotope compositions found at ocean islands, and are only slightly less than values found in mid-ocean ridge basalts (7-9 R A). This suggests that the recycled materials were injected into the mantle within the last 10 9 yrs.

  16. Primordial helium and the cosmic background radiation

    SciTech Connect

    Steigman, Gary

    2010-04-01

    The products of primordial nucleosynthesis, along with the cosmic microwave background (CMB) photons, are relics from the early evolution of the Universe whose observations probe the standard model of cosmology and provide windows on new physics beyond the standard models of cosmology and of particle physics. According to the standard, hot big bang cosmology, long before any stars have formed a significant fraction ( ∼ 25%) of the baryonic mass in the Universe should be in the form of helium-4 nuclei. Since current observations of {sup 4}He are restricted to low redshift regions where stellar nucleosynthesis has occurred, an observation of high redshift, prestellar, truly primordial {sup 4}He would constitute a fundamental test of the hot, big bang cosmology. At recombination, long after big bang nucleosynthesis (BBN) has ended, the temperature anisotropy spectrum imprinted on the CMB depends on the {sup 4}He abundance through its connection to the electron density and the effect of the electron density on Silk damping. Since the relic abundance of {sup 4}He is relatively insensitive to the universal density of baryons, but is sensitive to a non-standard, early Universe expansion rate, the primordial mass fraction of {sup 4}He, Yp, offers a test of the consistency of the standard models of BBN and the CMB and, provides constraints on non-standard physics. Here, the WMAP seven year data (supplemented by other CMB experiments), which lead to an indirect determination of Yp at high redshift, are compared to the BBN predictions and to the independent, direct observations of {sup 4}He in low redshift, extragalactic HII regions. At present, given the very large uncertainties in the CMB-determined primordial {sup 4}He abundance (as well as for the helium abundances inferred from HII region observations), any differences between the BBN predictions and the CMB observations are small, at a level ∼<1.5σ.

  17. Atmospheric helium isotope ratio: Possible temporal and spatial variations

    NASA Astrophysics Data System (ADS)

    Sano, Yuji; Furukawa, Yukiko; Takahata, Naoto

    2010-09-01

    The atmospheric 3He/ 4He ratio has been considered to be constant on a global scale, because the residence time of helium is significantly longer than the mixing time in the atmosphere. However, this ratio may be decreasing with time owing to the anthropogenic release of crustal helium from oil and natural gas wells, although this observation has been disputed. Here, we present the 3He/ 4He ratios of old air trapped in historical slags in Japan and of modern surface air samples collected at various sites around the world, measured with a newly developed analytical system. In air helium extracted from metallurgical slag found at refineries in operation between AD 1603 and 1907 in Japan, we determined a mean 3He/ 4He ratio of (5106 ± 108) × 10 -5 R HESJ (where R HESJ is the 3He/ 4He ratio of the Helium Standard of Japan), which is consistent with the previously reported value of (5077 ± 59) × 10 -5 R HESJ for historical slags in France and United Arab Emirates and about 4% higher than that of average modern air, (4901 ± 4) × 10 -5 R HESJ. This result implies that the air 3He/ 4He ratio has decreased with time as expected by anthropogenic causes. Our modern surface air samples revealed that the 3He/ 4He ratio increases from north to south at a rate of (0.16 ± 0.08) × 10 -5 R HESJ/degree of latitude, suggesting that the low 3He/ 4He ratio originates in high-latitude regions of the northern hemisphere, which is consistent with the fact that most fossil fuel is extracted and consumed in the northern hemisphere.

  18. Noble gases preserve history of retentive continental crust in the Bravo Dome natural CO2 field, New Mexico

    NASA Astrophysics Data System (ADS)

    Sathaye, Kiran J.; Smye, Andrew J.; Jordan, Jacob S.; Hesse, Marc A.

    2016-06-01

    Budgets of 4He and 40Ar provide constraints on the chemical evolution of the solid Earth and atmosphere. Although continental crust accounts for the majority of 4He and 40Ar degassed from the Earth, degassing mechanisms are subject to scholarly debate. Here we provide a constraint on crustal degassing by comparing the noble gases accumulated in the Bravo Dome natural CO2 reservoir, New Mexico USA, with the radiogenic production in the underlying crust. A detailed geological model of the reservoir is used to provide absolute abundances and geostatistical uncertainty of 4He, 40Ar, 21Ne, 20Ne, 36Ar, and 84Kr. The present-day production rate of crustal radiogenic 4He and 40Ar, henceforth referred to as 4He* and 40Ar*, is estimated using the basement composition, surface and mantle heat flow, and seismic estimates of crustal density. After subtracting mantle and atmospheric contributions, the reservoir contains less than 0.02% of the radiogenic production in the underlying crust. This shows unequivocally that radiogenic noble gases are effectively retained in cratonic continental crust over millennial timescales. This also requires that approximately 1.5 Gt of mantle derived CO2 migrated through the crust without mobilizing the crustally accumulated gases. This observation suggests transport along a localized fracture network. Therefore, the retention of noble gases in stable crystalline continental crust allows shallow accumulations of radiogenic gases to record tectonic history. At Bravo Dome, the crustal 4He*/40Ar* ratio is one fifth of the expected crustal production ratio, recording the preferential release of 4He during the Ancestral Rocky Mountain orogeny, 300 Ma.

  19. Grand Comore Island: A well-constrained “low 3He/4He” mantle plume

    NASA Astrophysics Data System (ADS)

    Class, Cornelia; Goldstein, Steven L.; Stute, Martin; Kurz, Mark D.; Schlosser, Peter

    2005-05-01

    We report He isotope ( 3He/ 4He) variations in samples from alkali basaltic and basanitic lava flows from Grande Comore Island complemented by existing [1,2] [C. Class, S.L. Goldstein, Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy. Earth Planet. Sci. Lett., 150 (1997) 245-260, C. Class, S.L. Goldstein, R. Altherr, P. Bachèchlery, The process of plume-lithosphere interaction in the ocean basins—the case of Grande Comore. J. Petrol., 39 (5) (1998) 881-903] and new Sr-Nd-Pb isotope ratios and major and trace element abundances. He isotope data in samples from Tristan da Cunha and Gough islands and the Huri Hills in Kenya are reported also. Grande Comore 3He/ 4He ratios vary between 5.05 and 7.08 RA ( 4He/ 3He ≈ 141,000-101,000). Chemical and Sr-Nd-Pb isotopic variations of Grande Comore lavas were previously shown to reflect melts derived from the deep mantle plume and the shallow lithospheric mantle [1-3] [C. Class, S.L. Goldstein, Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy. Earth Planet. Sci. Lett., 150 (1997) 245-260, C. Class, S.L. Goldstein, R. Altherr, P. Bachèchlery, The process of plume-lithosphere interaction in the ocean basins-the case of Grande Comore. J. Petrol., 39 (5) (1998) 881-903, C. Claude-Ivanaj, B. Bourdon, C.J. Allègre, Ra-Th-Sr isotope systematics in Grande Comore Island: a case study of plume-lithosphere interaction. Earth Planet. Sci. Lett. 164 (1998) 99-117]. The lithosphere-dominated end-member (La Grille volcano) shows uniform 3He/ 4He ratios within error of 6.75-7.08 RA ( 4He/ 3He ≈ 106,000-101,000) over a range of [He] = 36-428 × 10 - 9 ccSTP/g. The plume end-member (of the Karthala volcano suite), as constrained by Sr, Nd, Pb isotope ratios, shows uniformly lower 3He/ 4He ratios with 5.05-5.41 RA ( 4He/ 3He ≈ 141,000-132,000) over a range of [He] = 11-136 × 10 - 9 ccSTP/g. All samples show good correlations between Sr-Nd-He isotope

  20. Helium, Carbon, and Helium Isotopes in the Northern Lau Basin

    NASA Astrophysics Data System (ADS)

    Lupton, J. E.; Butterfield, D. A.; Lilley, M. D.; Resing, J.; Embley, R. W.; Arculus, R. J.; Rubin, K. H.; Evans, L.; Greene, R.

    2009-12-01

    Helium isotope ratios in hydrothermal fluids and volcanic rocks in the northern Lau Basin show a complex pattern reflecting influences from diverse mantle sources, including the Samoan hotspot, the Tofua Arc, and mid-ocean ridge (MOR)-type upper mantle. The Samoan Islands represent a “high 3He” hotspot with 3He/4He ratios up to 38 Ra (where Ra is the 3He/4He ratio in air, 1.39 x 10-6) [Farley et al, 1992; Jackson et al., 2007]. In contrast to the 3He-rich helium in Samoa, typical back-arc spreading centers have MOR-type helium values of 7-9 Ra, while volcanic arcs have lower ratios of 5-7 Ra. In the northwestern part of the Lau Basin, basalt samples from the Northwest Lau Spreading Center and the Rochambeau Rifts have 3He/4He varying from 11 to 28 Ra, far above typical back-arc or MOR values. These elevated 3He/4He ratios indicate that the Samoan hotspot signal has somehow penetrated southward into the northern Lau Basin, presumably through a tear in the subducting Pacific Plate. In the northeastern Lau Basin, 3He/4He ratios in hydrothermal fluids from two sites on the Northeast Lau Spreading Center have 3He/4He of 8.0 and 8.7 Ra. These are MOR-type values typical for a back-arc spreading center. At the actively erupting West Mata volcano, vent fluids have 3He/4He of 7.3 Ra, while farther east at Volcano P analysis of water-column plume samples gave a value of 6.7 Ra for the estimated end-member 3He/4He value. This decrease in 3He/4He going toward the east indicates increasing arc influence with increasing proximity to the Tofua Arc. This interpretation is supported by the C/3He ratios in the hydrothermal fluids, which average 1-3 x 109 at vent sites on the NELSC (typical MOR values) and increase to a typical arc value of 2 x 1010 at West Mata. Analyses of volcanic rocks from the eruption sites on the NELSC and West Mata are in progress and should help to further define these variations.

  1. Does the "mantle" helium signature provide useful information about lithospheric architecture of Tibet/Himalaya?

    NASA Astrophysics Data System (ADS)

    Klemperer, S. L.; Liu, T.; Hilton, D. R.; Karlstrom, K. E.; Crossey, L. J.; Zhao, P.

    2015-12-01

    Measurements of 3He/4He > 0.1*Ra (where Ra = 3He/4He in Earth's atmosphere) in geothermal fluids are conventionally taken to represent derivation from a mantle source. 3He/4He values < 0.1*Ra are taken to represent only radiogenic helium with no modern mantle input (the canonical 3He/4He ratio for the crust is 0.02*Ra). Upward transport rates are hard to constrain, but transit times of 3He through the crust in a CO2-rich carrier fluid may be as short as a few years, so 3He/4He measurements offer a proxy for mantle temperature on geologically short time-scales. In Tibet, enhanced 3He/4He ratios could in principle represent (1) incipient partial melt of Indian lithospheric mantle; (2) of Asian lithospheric mantle; (3) upwelling asthenosphere north of underthrust India or along tears in the subducting Indian plate; and/or (4) high-T prograde metamorphism releasing previously trapped 3He from older, voluminous mafic/ultramafic rocks in the crust. We present data from our recent field campaigns and our compilations from the western and Chinese literature. Any individual observation of 3He/4He > 0.1*Ra may still be argued to result from mantle-derived 3He previously stored in the crust. However, our growing regional database of widely spaced observations of 3He/4He > 0.1*Ra, from the Karakoram Fault in the west to the Sangri-Cona rift and Yalaxiangbo Dome in the east, and from south of the Yarlung-Zangbo suture (YZS) to north of the Banggong-Nujiang suture, makes such special pleading increasingly implausible. The observation of 3He/4He > 0.1*Ra at the YZS and even within the Tethyan Himalaya south of the YZS cannot represent melting of Indian mantle close to the Moho unless existing thermal models are grossly in error. The source of 3He close to the YZS is likely either asthenosphere accessed by faults and shear zones that cut through subducting Indian lithospheric mantle; or incipient melt of Asian lithospheric mantle at the Moho north of the northern edge of

  2. Detailed Distribution of the Helium Isotope Ratios in Northeastern Japan

    NASA Astrophysics Data System (ADS)

    Horiguchi, K.; Ueki, S.; Sano, Y.; Takahata, N.; Hasegawa, A.

    2007-12-01

    The geographical distribution of helium isotope ratios (3He/4He ratios) is characterized by high values of 4 to 8RA (where RA is the atmospheric 3He/4He ratio of 1.39×10-6) along the volcanic front and in the back-arc region at Tohoku district, northeastern Japan. In contrast forearc region shows low values less than 1RA. On the other hand, there is no clear contrast of the 3He/4He ratios except at the central region (e.g., Sano and Wakita, 1985). We perform the helium isotope ratio analysis in northeastern Japan, and around the source region of the Niigataken Chuetsu-oki Earthquake in 2007 (M6.8) where 3He/4He ratios data were reported. We have collected 41 samples of gases from hot springs, mineral springs, and deep wells, distributing mainly in the forearc region at Tohoku district. In addition, we also collected 19 samples of gases from hot springs, volcanoes and natural gas fields around the source region of the Niigataken Chuetsu-oki Earthquake in 2007. We measured 3He/4He ratios by noble gas mass spectrometers (Helix and VG5400) of Ocean Research Institute (ORI), the University of Tokyo. The 4He/20Ne were measured by a quadruple mass spectrometer to evaluate air contamination in the samples. δ13C (CO2) values were measured by using a mass spectrometer (DELTA plus XP) of ORI. Main features of our results for Tohoku region are as follows: 1) The 3He/4He ratios in the forearc region are less than 1RA. 2) The 3He/4He ratios vary along the volcanic front. In Miyagi prefecture [38-39N], the ratios range from 2 to 5 RA. On the other hand, the ratios are less than 1RA in and around the southern boundary of Iwate and Akita prefectures [39-39.5N]. The distribution of 3He/4He ratios in Niigata plans to be discussed by comparing with the well-studied seismotectonics and the structure of the crust and upper mantle.

  3. Insights from fumarole gas geochemistry on the origin of hydrothermal fluids on the Yellowstone Plateau

    USGS Publications Warehouse

    Chiodini, Giovanni; Caliro, Stefano; Lowenstern, Jacob B.; Evans, William C.; Bergfeld, D.; Tassi, Franco; Tedesco, Dario

    2012-01-01

    The chemistry of Yellowstone fumarole gases shows the existence of two component waters, type MC, influenced by the addition of deep mantle fluid, and type CC, influenced by crustal interactions (CC). MC is high in 3He/4He (22 Ra) and low in 4He/40Ar (~1), reflecting input of deep mantle components. The other water is characterized by 4He concentrations 3-4 orders of magnitude higher than air-saturated meteoric water (ASW). These high He concentrations originate through circulation in Pleistocene volcanic rocks, as well as outgassing of Tertiary and older (including Archean) basement, some of which could be particularly rich in uranium, a major 4He source. Consideration of CO2-CH4-CO-H2O-H2 gas equilibrium reactions indicates equilibration temperatures from 170 °C to 310 °C. The estimated temperatures highly correlate with noble-gas variations, suggesting that the two waters differ in temperature. Type CC is ~170 °C whereas the MC is hotter, at 340 °C. This result is similar to models proposed by previous studies of thermal water chemistry. However, instead of mixing the deep hot component simply with cold, meteoric waters we argue that addition of a 4He-rich component, equilibrated at temperatures around 170 °C, is necessary to explain the range in fumarole gas chemistry.

  4. No evidence for change of the atmospheric helium isotope composition since 1978 from re-analysis of the Cape Grim Air Archive

    NASA Astrophysics Data System (ADS)

    Mabry, Jennifer C.; Lan, Tefang; Boucher, Christine; Burnard, Peter G.; Brennwald, Matthias S.; Langenfelds, Ray; Marty, Bernard

    2015-10-01

    The helium isotope composition of air might have changed since the industrial revolution due to the release of 4He-rich crustal helium during exploitation of fossil fuels. Thereby, variation of the atmospheric helium isotope ratio (3He/4He) has been proposed as a possible new atmospheric tracer of industrial activity. However, the magnitude of such change is debated, with possible values ranging from 0 to about 2 ‰ /yr (Sano et al., 1989; Hoffman and Nier, 1993; Pierson-Wickmann et al., 2001; Brennwald et al., 2013; Lupton and Evans, 2013). A new analytical facility for high precision (2‰, 2σ) analysis of the 3He/4He ratio of air has been developed at CRPG Nancy (France) capable of investigating permil level variations. Previously, Brennwald et al. (2013) analyzed a selection of air samples archived since 1978 at Cape Grim, Tasmania, by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). They reported a mean temporal decrease of the 3He/4He ratio of 0.23-0.30‰/yr. Re-analysis of aliquots of the same samples using the new high-precision instrument showed no significant temporal decrease of the 3He/4He ratio (0.0095 ± 0.033‰ /yr, 2σ) in the time interval 1978-2011. These new data constrain the mean He content of globally produced natural gas to about 0.034% or less, which is about 3× lower than commonly quoted.

  5. Helium isotopic variations in volcanic rocks from Loihi Seamount and the Island of Hawaii

    USGS Publications Warehouse

    Kurz, M.D.; Jenkins, W.J.; Hart, S.R.; Clague, D.

    1983-01-01

    Helium isotopic ratios ranging from 20 to 32 times the atmospheric 3He 4He(RA) have been observed in a suite of 15 basaltic glasses from the Loihi Seamount. These ratios, which are up to four times higher than those of MORB glasses and more than twice those of nearby Kilauea, are strongly suggestive of a primitive source of volatiles supplying this volcanism. The Loihi glasses measured span a broad compositional range, and the 3He/4He ratios were found to be generally lower for the alkali basalts than for the tholeiites. The component with a lower 3He 4He ratio appears to be associated with olivine xenocrysts, within which fluid inclusions are probably the carrier of contaminant helium. One Loihi sample has a much lower isotopic ratio ( 30 RA) helium with some (variable) component of lithospheric contamination added during "breakthrough", while the later stages are characterized by a relaxation toward lithospheric 3He 4He ratios (??? 8 RA) due to isolation of the diapir from the mantle below (as the plate moves on), and subsequent mining of the inherited helium and contamination from the surrounding lithosphere. The abrupt contrast in 3He 4He ratios between Kilauea and Loihi, despite their close proximity, is indicative of the small lateral extent of the plume. ?? 1983.

  6. Light Isotope Abundances in SEPS measured by NINA

    NASA Astrophysics Data System (ADS)

    Sparvoli, R.; Bidoli, V.; Casolino, M.; De Pascale, M.; Furano, G.; Iannucci, A.; Morselli, A.; Picozza, P.; Bakaldin, A.; Galper, A.; Koldashov, S.; Korotkov, M.; Leonov, A.; Mikhailov, V.; Murashov, A.; Voronov, S.; Boezio, M.; Bonvicini, V.; Cirami, R.; Vacchi, A.; Zampa, N.; Ambriola, M.; Bellotti, R.; Cafagna, F.; Ciacio, F.; Circella, M.; De Marzo, C.; Adriani, O.; Papini, P.; Spillantini, P.; Straulino, S.; Vannuccini, E.; Bartalucci, S.; Ricci, M.; Castellini, G.; Wizard-NINA Collaboration

    2001-08-01

    Observations of 9 Solar Energetic Particle events detected by the instrument NINA from November 1998 to April 1999 will be presented. NINA is a silicon-based space detector in orbit since July 1998 on board the Russian satellite Resurs-01-N4, which flies at low altitude (about 800 km) in polar inclination. For every SEP event we reconstructed the power-law 4 He spectrum in the energy interval 10-50 MeV/n, extracting spectral indexes from 1.8 to 6.8. Data of 3 He and 4 He were then employed to determine the 3 He/4 He ratio, that turned out to be high for some SEP events showing the enrichment in 3 He. For the 7 November 1998 event this ratio reached the maximum value of 0.33 ± 0.06, with spectral indexes 2.5 ± 0.6 and 3.7 ± 0.3 for 3 He and 4 He, respectively. The 3 He/4 He ratio averaged over the remaining events was 0.011 ± 0.004. For all events we determined the deuterium-to-proton ratio. The average value of the 2 H/1 H ratio, over all events, was (3.9±1.4)× 10-5 in the energy interval 9-12 MeV/n. During 24 November 1998 event, however, this ratio resulted about 10 times higher than normal coronal values.

  7. Use of tritium and helium to define groundwater flow conditions in Everglades National Park

    NASA Astrophysics Data System (ADS)

    Price, René M.; Top, Zafer; Happell, James D.; Swart, Peter K.

    2003-09-01

    The concentrations of tritium (3H) and helium isotopes (3He and 4He) were used as tracers of groundwater flow in the surficial aquifer system (SAS) beneath Everglades National Park (ENP), south Florida. From ages determined by 3H/3He dating techniques, groundwater within the upper 28 m originated within the last 30 years. Below 28 m, waters originated prior to 30 years before present with evidence of mixing at the interface. Interannual variation of the 3H/3He ages within the upper 28 m was significant throughout the 3 year investigation, corresponding with varying hydrologic conditions. In the region of Taylor Slough Bridge, younger groundwater was consistently detected below older groundwater in the Biscayne Aquifer, suggesting preferential flow to the lower part of the aquifer. An increase in 4He with depth in the SAS indicated that radiogenic 4He produced in the underlying Hawthorn Group migrates into the SAS by diffusion. Higher Δ4He values in brackish groundwaters compared to fresh waters from similar depths suggested a possible enhanced vertical transport of 4He in the seawater mixing zone. Groundwater salinity measurements indicated the presence of a wide (6-28 km) seawater mixing zone. Comparison of groundwater levels with surface water levels in this zone indicated the potential for brackish groundwater discharge to the overlying Everglades surface water.

  8. Helium 4 and radon 222 concentrations in groundwater and soil as indicators of zones of fracture concentration in unexposed rock

    SciTech Connect

    Banwell, G.M.; Parizek, R.R.

    1988-01-10

    The presence of zones of fracture concentration in unexposed rock may be partially assessed by measuring the concentrations of /sup 4/He and /sup 222/Rn in groundwater and soil gas. Helium 4 in groundwater and soil gas and /sup 222/Rn in groundwater were measured in the vicinity of two intersecting linements in Lehigh County, Pennsylvania. The limeaments are thought to mark deep fracture systems which provide conduits for the migration of /sup 4/He and /sup 222/Rn. High groundwater /sup 4/He concentrations revealed the presence of the two lineaments. Low groundwater /sup 222/Rn activities are found near the lineaments and qualitatively support a numerical model which relates low /sup 222/Rn activity to high fracture transmissivity. Radon 222 activity correlates most strongly with the presence of H/sub 2/S in groundwater, implying that geochemical controls or groundwater circulation patterns strongly influence radon concentration. Soil gas concentrations of /sup 4/He barely exceeded background levels and did not reliably indicate the lineament zones. The data show that groundwater /sup 4/He concentrations may be used to identify fracture zones in unexposed bedrock. copyright American Geophysical Union 1988

  9. A 3He Cryostat for Scientific Measurements in Pulsed High Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Wang, Shaoliang; Li, Liang; Liu, Mengyu; Zuo, Huakun; Peng, Tao

    A top loading 3He cryostat has been developed for scientific experiments with a 60 T pulsed magnetic field facility at Wuhan National High Magnetic Field Center. The cryostat consists of a 4He bath cryostat, a 3He insert and a closed circulation system for 3He gas handling. To eliminate the eddy current heating during the pulse, the tail of the 3He insert with a vacuum space at the bottom is made from fiberglass tubing coated with epoxy. The 3He bath is separated from the 4He bath with the vacuum space. The 4He bath cryostat provides cooling power to condense 3He gas by a neck tube on top of the tail. Experimental results have shown that the sample can be cooled down to 385 mK and kept cold for more than 150 second by one-shot cooling, which is sufficiently long for an experiment in a pulsed high magnetic field.

  10. Description of light nuclei in pionless effective field theory using the stochastic variational method

    NASA Astrophysics Data System (ADS)

    Lensky, Vadim; Birse, Michael C.; Walet, Niels R.

    2016-09-01

    We construct a coordinate-space potential based on pionless effective field theory (EFT) with a Gaussian regulator. Charge-symmetry breaking is included through the Coulomb potential and through two- and three-body contact interactions. Starting with the effective field theory potential, we apply the stochastic variational method to determine the ground states of nuclei with mass number A ≤4 . At next-to-next-to-leading order, two out of three independent three-body parameters can be fitted to the three-body binding energies. To fix the remaining one, we look for a simultaneous description of the binding energy of 4He and the charge radii of 3He and 4He. We show that at the order considered we can find an acceptable solution, within the uncertainty of the expansion. We find that the EFT expansion shows good agreement with empirical data within the estimated uncertainty, even for a system as dense as 4He.

  11. Bound and scattering states with non-local potentials.

    SciTech Connect

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

    2007-06-01

    The application of the hyperspherical harmonics method to the case of non-local potentials is described. Given the properties of the hyperspherical harmonic functions, there are no difficulties in considering the approach in both coordinate and momentum space. The results for the 3H and 4He binding energies and n - 3H scattering lengths are found to be in good agreement with those obtained with other different techniques. A study of the 4He form factor is also reported, with a careful investigation of the contribution from isospin symmetry violation. Its effect on parity violating elastic scattering of polarized electrons from 4He is investigated. In particular, a simple analysis of the recently measured left-right asymmetry at low Q2 shows that the contribution of these isospin admixture are found of comparable magnitude to that associated with strangeness components in the nucleon electric form factor.

  12. Bose-Einstein condensation and spin mixtures of optically trapped metastable helium

    SciTech Connect

    Partridge, G. B.; Jaskula, J.-C.; Bonneau, M.; Boiron, D.; Westbrook, C. I.

    2010-05-15

    We report the realization of a Bose-Einstein condensate of metastable helium-4 atoms ({sup 4}He*) in an all-optical potential. Up to 10{sup 5} spin-polarized {sup 4}He* atoms are condensed in an optical dipole trap formed from a single, focused, vertically propagating far-off-resonance laser beam. The vertical trap geometry is chosen to best match the resolution characteristics of a delay-line anode microchannel plate detector capable of registering single He* atoms. We also confirm the instability of certain spin-state combinations of {sup 4}He* to two-body inelastic processes, which necessarily affects the scope of future experiments using optically trapped spin mixtures. In order to better quantify this constraint, we measure spin-state-resolved two-body inelastic loss rate coefficients in the optical trap.

  13. Quiet-time periods observed by EPHIN/SOHO during the minimum of the 22nd solar cycle

    NASA Astrophysics Data System (ADS)

    Gómez-Herrero, Raúl; RodrÍguez-FrÍas, M. Dolores; del Peral, Luis; Sequeiros, Juan; Müller-Mellin, Reinhold; Kunow, Horst; Sierks, Holger

    2000-06-01

    An analysis of the hydrogen and helium isotopic composition from EPHIN data, during the quiet-time period from January 1 to June 1, 1996, is presented. An isotopic discrimination and background rejection have been applied and relationships between the abundances of ^2H/^1H, ^3He/^4He, and ^4He/^1H have been calculated. The energy spectra in the 4-50 MeV nucl^-1 range have been obtained and the contribution of the different spectral components have been analysed in this energy range. We conclude that the main contribution to the ^4He spectrum is of anomalous origin, while the proton and ^3He spectra have contributions mainly from particles of solar origin at low energies and from the galactic cosmic radiation modulated by the heliosphere at high energies. The deuterium spectrum is mainly of galactic origin.

  14. Ab Initio Many-Body Calculations Of Nucleon-Nucleus Scattering

    SciTech Connect

    Quaglioni, S; Navratil, P

    2008-12-17

    We develop a new ab initio many-body approach capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group method with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters. This approach preserves translational symmetry and Pauli principle. We outline technical details and present phase shift results for neutron scattering on {sup 3}H, {sup 4}He and {sup 10}Be and proton scattering on {sup 3,4}He, using realistic nucleon-nucleon (NN) potentials. Our A = 4 scattering results are compared to earlier ab initio calculations. We find that the CD-Bonn NN potential in particular provides an excellent description of nucleon-{sup 4}He S-wave phase shifts. We demonstrate that a proper treatment of the coupling to the n-{sup 10}Be continuum is successful in explaining the parity-inverted ground state in {sup 11}Be.

  15. Nonlocal Separable Solutions of the Inverse Scattering Problem

    NASA Astrophysics Data System (ADS)

    Gherghetta, Tony; Nambu, Yoichiro

    We extend the nonlocal separable potential solutions of Gourdin and Martin for the inverse scattering problem to the case where sin δ0 has more than N zeroes, δ0 being the s-wave scattering phase shift and δ0(0) - δ0(∞) = Nπ. As an example we construct the solution for the particular case of 4He and show how to incorporate a weakly bound state. Using a local square well potential chosen to mimic the real 4He potential, we compare the off-shell extension of the nonlocal potential solution with the exactly solvable square well. We then discuss how a nonlocal potential might be used to simplify the many-body problem of liquid 4He.

  16. Big bang nucleosynthesis revisited via Trojan Horse method measurements

    SciTech Connect

    Pizzone, R. G.; Spartá, R.; Spitaleri, C.; La Cognata, M.; Tumino, A.; Bertulani, C. A.; Lalmansingh, J.; Lamia, L.; Mukhamedzhanov, A.

    2014-05-10

    Nuclear reaction rates are among the most important input for understanding primordial nucleosynthesis and, therefore, for a quantitative description of the early universe. An up-to-date compilation of direct cross-sections of {sup 2}H(d, p){sup 3}H, {sup 2}H(d, n){sup 3}He, {sup 7}Li(p, α){sup 4}He, and {sup 3}He(d, p){sup 4}He reactions is given. These are among the most uncertain cross-sections used and input for big bang nucleosynthesis calculations. Their measurements through the Trojan Horse method are also reviewed and compared with direct data. The reaction rates and the corresponding recommended errors in this work were used as input for primordial nucleosynthesis calculations to evaluate their impact on the {sup 2}H, {sup 3,4}He, and {sup 7}Li primordial abundances, which are then compared with observations.

  17. Measurements of energetic helium-3 minority distributions during ion cyclotron radio-frequency heating in the Princeton Large Torus

    SciTech Connect

    Hammett, G.W.; Kaita, R.; Wilson, J.R.

    1988-03-01

    Ion cyclotron radio-frequency heating experiments were performed with a /sup 3/He minority ion species in a /sup 4/He majority plasma in the Princeton Large Torus. The energetic /sup 3/He ion ''tail'' was measured directly with a charge exchange neutral analyzer for the first time. Comparisons with bounce-averaged quasi-linear calculations suggest a modestly peaked radi-frequency power deposition profile. The double charge exchange process /sup 3/He/sup + +/ )plus) /sup 4/He/sup 0/ )plus) /sup 3/He/sup 0/ )plus) /sup 4/He/sup + +/ demonstrated in these measurements may be useful as part of an alpha particle diagnostic in a fusion reactor experiment. 18 refs., 4 figs.

  18. Experiments on nuclear fission induced by radioactive beams

    SciTech Connect

    Skobelev, N.K.

    1994-07-01

    The cross sections of {sup 209}Bi nuclear fission induced by secondary beams of {sup 6}He and {sup 4}He are measured under identical conditions. The experimental data are in good agreement with earlier results on the fission cross section of the {sup 4}He + {sup 209}Bi reaction. The measured values of the cross section of {sup 209}Bi fission induced by {sup 6}He ions are much higher than the cross sections of fission induced by {alpha}-particles. It is found that the fission threshold for the {sup 6}He + {sup 209}Bi reaction is shifted as compared to that of the {sup 4}He + {sup 209}Bi reaction. Various factors that can be responsible for the observed peculiarities in the {sup 209}Bi fission induced by the {sup 6}He ions are analyzed. 25 refs., 5 figs.

  19. Anomalies of mantle-derived helium during the 1997-1998 seismic swarm of Umbria-Marche, Italy

    NASA Astrophysics Data System (ADS)

    Italiano, F.; Martinelli, G.; Nuccio, P. M.

    More than 100 ³He/4He isotope ratios were measured in CO2-dominated gas samples collected during the 1997-1998 seismic crisis that shook the Umbria-Marche, Central Apennines, Italy. Although the gas emissions were located in a typical “crustal” environment the measured values delineate variable mixing proportions between mantle-derived and crustal helium. During the monitoring period anomalous ³He/4He ratios were observed, together with a significant increase of fluid outflows. The observed ³He/4He anomalies appear to be driven by stress-induced crustal deformations affecting micro-fracturing and bulk permeability and, in turn, by a seismogenic-induced modification of the crustal permeability of rocks. Since crustal deformations can also occur aseismically, the geochemical anomalies must be considered indicators of processes occurring below the surface, which could eventually help to estimate the probability increase of an impending earthquake, instead of pure empirical precursors.

  20. General integral relations for the description of scattering states using the hyperspherical adiabatic basis

    SciTech Connect

    Romero-Redondo, C.; Garrido, E.; Barletta, P.; Kievsky, A.; Viviani, M.

    2011-02-15

    In this work we investigate 1+2 reactions within the framework of the hyperspherical adiabatic expansion method. With this aim two integral relations, derived from the Kohn variational principle, are used. A detailed derivation of these relations is shown. The expressions derived are general, not restricted to relative s partial waves, and with applicability in multichannel reactions. The convergence of the K matrix in terms of the adiabatic potentials is investigated. Together with a simple model case used as a test for the method, we show results for the collision of a {sup 4}He atom on a {sup 4}He{sub 2} dimer (only the elastic channel open), and for collisions involving a {sup 6}Li and two {sup 4}He atoms (two channels open).

  1. Binding of two helium atoms in confined geometries

    SciTech Connect

    Kilic, S. |; Krotscheck, E.; Zillich, R.

    1999-08-01

    The authors carry out a comprehensive study of the binding of two helium atoms in unrestricted and, in particular, in restricted geometries in both two and three dimensions. Besides the well known binding of the {sup 4}He dimer in unrestricted geometry in two and three dimensions, the authors also find weakly bound states of the {sup 3}He-{sup 4}He molecule and the {sup 3}He dimer in 2 dimensions. Furthermore, any combination of two {sup 4}He or {sup 3}He atoms can form a molecule if their motion is sufficiently confined. The calculations are carried out by numerically solving the Schroedinger equation as well as by constructing a suitable variational wave function.

  2. /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.

  3. "Phoswich Wall": A charged-particle detector array for inverse-kinematic reactions with the Gretina/GRETA γ-ray arrays

    NASA Astrophysics Data System (ADS)

    Sarantites, D. G.; Reviol, W.; Elson, J. M.; Kinnison, J. E.; Izzo, C. J.; Manfredi, J.; Liu, J.; Jung, H. S.; Goerres, J.

    2015-08-01

    A high-efficiency, forward-hemisphere detector system for light charged particles and low-Z heavy ions, as obtained in an accelerator experiment, is described. It consists of four 8×8 pixel multianode photomultiplier tubes with 2.2-mm thick CsI(Tl) and 12 -μm thick fast-plastic scintillation detectors. Its phoswich structure allows individual Z resolution for 1H, 4He, 7Li, 4He+4He, 9Be, 11B, 12C, and 14N ions, which are target-like fragments detected in strongly inverse kinematics. The device design has been optimized for use with a 4π γ-ray array, and the main applications are transfer reactions and Coulomb excitation. A high-angular resolution for the detection of the target-like fragments is achieved which permits angular distributions to be measured in the rest frame of the projectile-like fragment with a resolution of ~ 2 °.

  4. Helium isotope, C/3He, and Ba-Nb-Ti signatures in the northern Lau Basin: Distinguishing arc, back-arc, and hotspot affinities

    NASA Astrophysics Data System (ADS)

    Lupton, John; Rubin, Ken H.; Arculus, Richard; Lilley, Marvin; Butterfield, David; Resing, Joseph; Baker, Edward; Embley, Robert

    2015-04-01

    The northern Lau Basin hosts a complicated pattern of volcanism, including Tofua Arc volcanoes, several back-arc spreading centers, and individual "rear-arc" volcanoes not associated with these structures. Elevated 3He/4He ratios in lavas of the NW Lau Spreading Center suggest the influence of a mantle plume, possibly from Samoa. We show that lavas from mid-ocean ridges, volcanic arcs, and hotspots occupy distinct, nonoverlapping fields in a 3He/4He versus C/3He plot. Applied to the northern Lau Basin, this approach shows that most of Lau back-arc spreading systems have mid-ocean ridge 3He/4He-C/3He characteristics, except the NW Lau spreading center, which has 3He/4He-C/3He similar to "high 3He" hotspots such as Loihi, Kilauea, and Yellowstone, but with slightly lower C/3He. Niua seamount, on the northern extension of the Tofua Arc, falls squarely in the arc field. All the NE Lau rear-arc volcanoes, including the recently erupting West Mata, also have arc-like 3He/4He-C/3He characteristics. Ba-Nb-Ti contents of the lavas, which are more traditional trace element indicators of mantle source enrichment, depletion, and subduction input, likewise indicate arc and hot spot influences in the lavas of the northern Lau Basin, but in a more ambiguous fashion because of a complex prior history. This verifies that 3He/4He-C/3He systematics are useful for differentiating between mid-ocean ridge, arc, and hotspot affinities in submarine volcanic systems, that all three of these affinities are expressed in the northern Lau Basin, and provides additional support for the Samoan plume influence in the region.

  5. Helium isotopes and mineralogy of hydrothermal ores from the Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Ooki, M.; Takahata, N.; Sano, Y.; Kagoshima, T.; Ishibashi, J.

    2012-12-01

    It is known that 3He/4He ratio of the typical mid-ocean ridge basalt (MORB) is 8±1.5 times higher than the atmospheric ratio, representative of the upper mantle. Similar high ratios have been observed in volcanic geothermal systems of subduction zones. To understand the origin of submarine hydrothermal fluids, we have measured helium isotopic ratios of fluid inclusions in hydrothermal ore deposits from the Okinawa Trough. Hydrothermal ore samples were collected during NT11-20 expedition using ROV Hyper-Dolphin(JAMSTEC), from Minami-Ensei Knoll, Yoron Knoll and Hatoma Knoll. Approximately 1 g of the ore sample picked up and put it in a stainless-steel crusher with a stainless-steel ball. Each ore sample was baked at approximately 200 degrees for 12 hours under vacuum to remove water and atmospheric components absorbed on surface. When the crusher was shaken up and down, the minerals in ores were crushed by the stainless-steel ball. Thus, gases in fluid inclusions were introduced into a vacuum line. These gases were purified, and helium-4 (4He) intensity and 3He/4He ratio were measured by a noble gas mass spectrometer, 4He/20Ne ratio and gas abundance (helium and neon) were measured by a quadrupole-based mass spectrometric system. Measured 3He/4He ratios of the most samples display obviously higher values than the atmospheric ratio (5~8Ratm). These values are slightly lower than or the same as that of MORB ratio. Conversely, measured 4He/20Ne ratios of samples show closer values to atmosphere than MORB. We discuss the fluid sources of Minami-Ensei Knoll, Yoron Knoll and Hatoma Knoll based on the helium isotopes as well as mineralogical features of hydrothermal ore samples.

  6. 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.

  7. Helium- and lead-isotope geochemistry of oceanic volcanic rocks from the East Pacific and South Atlantic. Doctoral thesis

    SciTech Connect

    Graham, D.W.

    1987-01-01

    Glassy basalts erupted at young Pacific seamounts and along the mid-ocean ridge in the South Atlantic, and volcanic rocks from the island of St. Helena were studied for He and Pb isotopes. (U+TH)/He ages of seamount alkali basalts were determined from the isotope disequilibrium of (3)He/(4)He between He trapped in vesicles and that dissolved in the glass phase. The method allows alkalic lavas to be dated in the age range of 103 to 106 years. Tholclites at the EPR seamounts have He, Pb, Sr and Nd isotope compositions indistinguishable from MORB, while associated alkali basalts show more radiogenic signatures. The low (3)He/(4)He in the vesicles of alkali basalts (1.2-2.6 RA), their low helium concentrations, and systematic variations with extent of differentiation suggest that magmatic processes influence (3)He/(4)He in these alkalic lavas. Pb-Sr-Nd isotopes at Shimada seamount (17 deg N, 117 deg W) indicate the presence of enriched mantle beneath the East Pacific which resembles that beneath Samoa. Low (3)He/(4)He (4-5 RA) appears to be an inherent characteristic of the component. Much of the South Atlantic ridge axis displays (3)He/(4)He lower than normal MORB, and is apparently contaminated by off-axis hotspots. He-Pb systematics along the ridge suggest that (3)He/(4)He at St. Helena is less than MORB, consistent with values measured by in vacuo crushing of olivine and pyroxene in St. Helena rocks (approx. 5.8 RA).

  8. The Chemical Evolution of Helium

    NASA Astrophysics Data System (ADS)

    Balser, Dana S.

    2006-12-01

    We report on measurements of the 4He abundance toward the outer Galaxy H II region S206 with the NRAO Green Bank Telescope. Observations of hydrogen and helium radio recombination lines between 8 and 10 GHz were made toward the peak radio continuum position in S206. We derive 4He/H=0.08459+/-0.00088 (random)+/-0.0010 (known systematic), 20% lower than optical recombination line results. It is difficult to reconcile the large discrepancy between the optical and radio values even when accounting for temperature, density, and ionization structure or for optical extinction by dust. Using only M17 and S206 we determine ΔY/ΔZ=1.41+/-0.62 in the Galaxy, consistent with standard chemical evolution models. High helium abundances in the old stellar population of elliptical galaxies can help explain the increase in UV emission with shorter wavelength between 2000 and 1200 Å, called the ``UV upturn'' or UVX. Our lower values of ΔY/ΔZ are consistent with a normal helium abundance at higher metallicity and suggest that other factors, such as a variable red giant branch mass loss with metallicity, may be important. When combined with 4He abundances in metal-poor galaxy H II regions, Magellanic Cloud H II regions, and M17 that have been determined from optical recombination lines, including the effects of temperature fluctuations, our radio 4He/H abundance ratio for S206 is consistent with a helium evolution of ΔY/ΔZ=1.6. A linear extrapolation to zero metallicity predicts a 4He/H primordial abundance ratio about 5% lower than that given by the Wilkinson Microwave Anisotropy Probe and standard big bang nucleosynthesis. The measured 4He abundances may be systematically underestimated by a few percent if clumping exists in these H II regions.

  9. New measurements of the European Muon Collaboration effect in very light nuclei.

    PubMed

    Seely, J; Daniel, A; Gaskell, D; Arrington, J; Fomin, N; Solvignon, P; Asaturyan, R; Benmokhtar, F; Boeglin, W; Boillat, B; Bosted, P; Bruell, A; Bukhari, M H S; Christy, M E; Clasie, B; Connell, S; Dalton, M M; Day, D; Dunne, J; Dutta, D; El Fassi, L; Ent, R; Fenker, H; Filippone, B W; Gao, H; Hill, C; Holt, R J; Horn, T; Hungerford, E; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, M; Lee, C; Lung, A F; Malace, S; Meekins, D G; Mertens, T; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Niculescu, I; Nomura, H; Okayasu, Y; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Segbefia, E; Slifer, K; Smith, G R; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Trojer, R; Tvaskis, V; Vulcan, W F; Wesselmann, F R; Wood, S A; Wright, J; Yuan, L; Zheng, X

    2009-11-13

    New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from (2)H, (3)He, (4)He, (9)Be and (12)C for 0.3 < x < 0.9, Q(2) approximately 3-6 GeV(2). These data represent the first measurement of the EMC effect for (3)He at large x and a significant improvement for (4)He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment. PMID:20365978

  10. The DD Cold Fusion-Transmutation Connection

    NASA Astrophysics Data System (ADS)

    Chubb, Talbot A.

    2005-12-01

    LENR theory must explain dd fusion, alpha-addition transmutations, radiationless nuclear reactions, and three-body nuclear particle reactions. Reaction without radiation requires many-body D Bloch+ periodicity in both location and internal structure dependencies. Electron scattering leads to mixed quantum states. The radiationless dd fusion reaction is 2-D Bloch+ -> {}4 He Bloch2+. Overlap between {}4 He Bloch2+ and surface Cs leads to alpha absorption. In the Iwamura et al. studies active deuterium is created by scattering at diffusion barriers.

  11. Theory of the Helium Isotope Shift

    SciTech Connect

    Pachucki, Krzysztof; Yerokhin, V. A.

    2015-09-15

    Theory of the isotope shift of the centroid energies of light few-electron atoms is reviewed. Numerical results are presented for the isotope shift of the 2{sup 3}P-2{sup 3}S and 2{sup 1}S-2{sup 3}S transition energies of {sup 3}He and {sup 4}He. By comparing theoretical predictions for the isotope shift with the experimental results, the difference of the squares of the nuclear charge radii of {sup 3}He and {sup 4}He, δR{sup 2}, is determined with high accuracy.

  12. Big bang nucleosynthesis: An update

    SciTech Connect

    Olive, Keith A.

    2013-07-23

    An update on the standard model of big bang nucleosynthesis (BBN) is presented. With the value of the baryon-tophoton ratio determined to high precision by WMAP, standard BBN is a parameter-free theory. In this context, the theoretical prediction for the abundances of D, {sup 4}He, and {sup 7}Li is discussed and compared to their observational determination. While concordance for D and {sup 4}He is satisfactory, the prediction for {sup 7}Li exceeds the observational determination by a factor of about four. Possible solutions to this problem are discussed.

  13. Simultaneous magneto-optical trapping of a boson-fermion mixture of metastable helium atoms.

    PubMed

    Stas, R J W; McNamara, J M; Hogervorst, W; Vassen, W

    2004-07-30

    We simultaneously confine fermionic metastable 3He atoms and bosonic metastable 4He atoms in a magneto-optical trap. The trapped clouds, containing up to 1.5 x 10(8) atoms of each isotope, are characterized by measuring ions and metastable helium atoms escaping from the trap. Optical pumping of 3He atoms to a nontrapped hyperfine state is investigated and it is shown that large atom numbers can be confined without additional repumping lasers. Unique possibilities for quantum degeneracy experiments with mixtures of spin-polarized metastable 3He and 4He atoms are indicated.

  14. Charge-symmetry breaking {Lambda}-nucleon interaction

    SciTech Connect

    Bodmer, A.R.; Murali, M.; Usmani, Q.N.

    1995-08-01

    Some time ago we showed that the charge-symmetry-breaking interaction, as obtained from the mass four hypernuclei ({sub {Lambda}}{sup 4}H, {sub {Lambda}}{sup 4}He), was spin-independent; a result which cannot be understood with the conventional meson-exchange models. The calculations of ({sub {Lambda}}{sup 4}H, {sub {Lambda}}{sup 4}He) are currently being extended to include noncentral nuclear and hypernuclear forces which could modify this result. At a more fundamental level we intend to study quark-structure contributions to the charge-symmetry-breaking interaction.

  15. Physical interpretation of astrophysical factor S(E) for stellar energies from the WKB approximation.

    NASA Astrophysics Data System (ADS)

    Beaumevieille, H.; Bouchemha, A.; Boudouma, Y.; Boughrara, A.; Ouichaoui, S.; Tsan, U. C.

    1999-02-01

    For "non-resonant" reactions, a physical interpretation of the astrophysical factor S(E) in terms of the Coulomb barrier penetration factor and an intrinsic nuclear factor is proposed. Using the WKB (Wentzel, Kramers, Brillouin) approximation to evaluate the penetrabilities at stellar energies, the authors point out a drastic difference between the absolute values if S(0) according to wether s or p waves dominate the reaction. The variation with energy of S(E) to first order can also sign the nature of the wave. An application for the 6Li(d,α)4He and 7Li(p,α)4He reactions is presented.

  16. He, Ne, Ar, C, O and H isotope systematics of geothermal fluids in the Lesser Antilles Islands Arc

    NASA Astrophysics Data System (ADS)

    Pedroni, Anselmo; Hammerschmidt, Konrad; Friedrichsen, Hans

    1999-02-01

    We present He, Ne, Ar, and C isotope analyses of hydrothermal brines and gases from fumaroles, hot springs, mofettes and hydrothermal exploration drillings on the major islands of the Lesser Antilles Arc. The origin of hydrothermal brines, which have been analyzed also for O and H isotopes, is essentially meteoric-hydrothermal. Air-corrected isotope compositions of helium (2.2 Rc/Ra < 3He/ 4He < 8.6 Rc/Ra) and carbon (-20 < δ 13C PDB < +0.5) are variable and require a variety of crustal and magmatic sources. The diversity of δ 13C PDB and 3He/CO 2 ratios within individual volcanic centres suggests that crustal sources (e.g., limestone) contaminate magmatic CO 2 en route from high-level magma reservoirs (depth < 15 km) to the surface. A similar contamination may be found for magmatic helium on distal springs. The 3He/ 4He signature of summit fumaroles, thought to reflect the 3He/ 4He signature of high-level magmas, shows a remarkable systematic variation along the arc. In addition, there is a correlation throughout the arc between published Sr, Pb, and Nd isotope signatures of lavas and the 3He/ 4He signatures of summit fumaroles. On the northern islands (Nevis, Montserrat, Guadeloupe, and Dominica) summit fumaroles have the N-MORB signature ( 3He/ 4He = 8 ± 1 R/Ra), and the isotope signature of lavas is not dissimilar from comparable intra-oceanic arc tholeiites elsewhere. Variable enrichments in radiogenic Sr and Pb have been reported for lavas of individual volcanic centres of the Southern Islands (Martinique, St.Lucia, and Grenada), and summit fumaroles on these centres match these variations by variable radiogenic He-enrichments, i.e., lower 3He/ 4He ratios. This correlation suggests that radiogenic Sr and Pb enrichments of lavas and low 3He/ 4He signatures on summit fumaroles have a common origin, i.e., a terrigenous contaminant derived from the Orinoco depositionary fan. Crustal assimilation is thought to decouple the He isotope system from any other

  17. The scaling rule for environmental organizing systems in a gravitational field.

    PubMed

    Fujiwara, Noboru

    2004-02-01

    A recent thermodynamics and information study examined the basis of a scaling rule for simple living organisms. The present paper examines a scaling rule for the relationship between the integrated scaled metabolic energy and the mass of a system for a wide range of masses, from animals to the 4He cores of main-sequence stars, considering the effect of gravitational energy. The expected specific scaled energy for animals and the 4He cores of main-sequence stars is 1600 times greater than the specific scaled energy for fundamental living organisms, such as unicellular organisms. This difference results from their organization in a gravitational field or the lack thereof.

  18. Rotational quenching of CS in ultracold 3He collisions

    NASA Astrophysics Data System (ADS)

    Kaur, Rajwant; Dhilip Kumar, T. J.

    2016-08-01

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

  19. Evaporative cooling of metastable helium in the multi-partial-wave regime

    SciTech Connect

    Nguyen, Scott V.; Doret, S. Charles; Connolly, Colin B.; Michniak, Robert A.; Doyle, John M.; Ketterle, Wolfgang

    2005-12-15

    Metastable helium is buffer gas cooled, magnetically trapped, and evaporatively cooled in large numbers. 10{sup 11} {sup 4}He{sup *} atoms are trapped at an initial temperature of 400 mK and evaporatively cooled into the ultracold regime, resulting in a cloud of 2{+-}0.5x10{sup 9} atoms at 1.4{+-}0.2 mK. Efficient evaporation indicates low collisional loss for {sup 4}He{sup *} in both the ultracold and multi-partial-wave regime, in agreement with theory.

  20. New measurements of the European Muon Collaboration effect in very light nuclei.

    SciTech Connect

    Arrington, J.; El Fassi, L.; Holt, R.; Potterveld, D. H.; Reimer, P. E.; Schulte, E.; Solvignon, P.; Zheng, X.; Seely, J.; Daniel, A.; Gaskell, D.; Asaturyan, R.

    2009-11-13

    New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from {sup 2}H, {sup 3}He, {sup 4}He, {sup 9}Be and {sup 12}C for 0.3 < x < 0.9, Q{sup 2} {approx} 3-6 GeV{sup 2}. These data represent the first measurement of the EMC effect for {sup 3}He at large x and a significant improvement for {sup 4}He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.

  1. New measurements of the EMC effect in very light nuclei

    SciTech Connect

    Seely, J; Gaskell, D; Arrington, J; Fomin, N; Solvignon, P; Asaturyan, R; Benmokhtar, F; Boeglin, W; Boillat, B; Bosted, P; Bruell, A; Bukhari, M.H.S.; Christy, M E; Clasie, B; Connell, S; Dalton, M; Day, D; Dunne, J; Dutta, D; El Fassi, L; Ent, R; Fenker, H; Filippone, B W; Gao, H; Hill, C; Holt, R J; Horn, T; Hungerford, E; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, K; Lee, C; Lung, A F; Malace, S; Meekins, D G; Mertens, T; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Niculescu, I; Nomura, H; Okayasu, Y; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Segbefia, E; Slifer, K; Smith, G R; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Trojer, R; Tvaskis, V; Villano, A

    2009-11-01

    New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from 2H, 3He, 4He, 9Be and 12C for 0.34He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.

  2. Combining dynamic and static depth profiling in low energy ion scattering

    SciTech Connect

    Veen, Rik ter; Fartmann, Michael; Kersting, Reinhard; Hagenhoff, Birgit

    2013-01-15

    The advantages of combining dynamic and static depth profiling in low energy ion scattering are demonstrated for an Si/SiO{sub x}/W/Al{sub 2}O{sub 3} ALD stack. Dynamic depth profiling can be used to calibrate static depth profiling. Energy losses of 152 and 215 eV/nm were found for 3 keV {sup 4}He{sup +} and 5 keV {sup 4}He{sup +} primary ions, respectively, for the experimental configuration used. This is in good agreement with the values used in the field. Static depth profiling can be used to recognize sputter artifacts in dynamic depth profiles.

  3. Renormalization-Group Theory Study of Superfluidity and Phase Separation of Helium Mixtures Immersed in Jungle-Gym Aerogel

    NASA Astrophysics Data System (ADS)

    Lopatnikova, Anna; Berker, A. Nihat

    1997-03-01

    Superfluidity and phase separation in ^3He-^4He mixtures immersed in jungle-gym (non-random) aerogel are studied by renormalization-group theory.(Phys. Rev. B, in press (1996)) Phase diagrams are calculated for a variety of aerogel concentrations. Superfluidity at very low ^4He concentrations and a depressed tricritical temperature are found at the onset of superfluidity. A superfluid-superfluid phase separation, terminating at an isolated critical point, is found entirely within the superfluid phase. These phenomena, and trends with respect to aerogel concentration, are explained by the connectivity and tenuousness of jungle-gym aerogel.

  4. Renormalization-group study of superfluidity and phase separation of helium mixtures immersed in a nonrandom aerogel

    NASA Astrophysics Data System (ADS)

    Lopatnikova, Anna; Nihat Berker, A.

    1997-02-01

    Superfluidity and phase separation in 3-4He mixtures immersed in a jungle-gym (nonrandom) aerogel are studied by renormalization-group theory. Phase diagrams are calculated for a variety of aerogel concentrations. Superfluidity at very low 4He concentrations and a depressed tricritical temperature are found at the onset of superfluidity. A superfluid-superfluid phase separation, terminating at an isolated critical point, is found entirely within the superfluid phase. These phenomena and trends with respect to aerogel concentration are explained by the connectivity and tenuousness of a jungle-gym aerogel.

  5. MeV He3/He4 isotope abundances in solar energetic particle events: SOHO/COSTEP observations

    NASA Astrophysics Data System (ADS)

    Bothmer, V.:; Sierks, H.; Böhm, E.; Kunow, H.

    2001-08-01

    We present first results based on a systematic survey of 4-41 MeV/N 3He/4He isotope abundances with ratios >0.01 detected by the COmprehensive SupraThermal and Energetic Particle analyzer (COSTEP) onboard the SOHO (SOlar and Heliospheric Observatory) spacecraft. More than about 25% of the identified events showed 3He/4He ratios in the range 0.1-1. For events with sufficiently high detector count rates the atomic mass plots can be resolved up to a time resolution of about 1 hour. These events are most suitable for comparisons with in situ solar wind plasma and magnetic field measurements and SOHO's optical white-light and extreme ultraviolet (EUV) observations of the Sun. The correlations show an association with passages of shock associated coronal mass ejections (CMEs) in the solar wind that inhibit high He/H plasma overabundances. It is likely that the CMEs have been released in strong magnetic reconfiguration processes at the solar source sites. Here we present a brief overview of such an event detected on October 30, 2000. 1. Introduction The SOHO/COSTEP instrument measures solar energetic particles (SEPs) at MeV energies in the interplanetary medium. The solid state detectors are capable to detect 3 He/4 He-enrichments at these energies (Müller-Mellin et al., 1995). Usually, the 3 He/4 He-ratio in the solar wind is at the order of 10-4 , but occasionally ratios up to about values of ~1 or even above have been observed in SEP events (e.g., Mason et al., 1999). The origin of these isotope abundances has commonly been attributed to impulsive solar flares and wave-particle interaction mechanisms (Temerin and Roth, 1992). However, fully satisfying physical explanations are still lacking. Here we present first results of a systematic survey of the He-measurements taken by COSTEP since launch in 1995 until the end of the year 2000. 2. Data For this study we have analyzed SOHO/COSTEP measurements of 4.3-40.9 MeV/N helium particles as well as COSTEP data covering

  6. Radiation Stability of Triple Coatings Based on Transition-Metal Nitrides Under Irradiation By Alpha Particles and Argon Ions

    NASA Astrophysics Data System (ADS)

    Potekaev, A. I.; Kislitsyn, S. B.; Uglov, V. V.; Klopotov, A. A.; Gorlachev, I. D.; Klopotov, V. D.; Grinkevich, L. S.

    2016-05-01

    The data on the influence of irradiation of (Ti, Cr)N1-x coatings by helium and argon ions on their surface structure are presented. The (Ti, Cr)N1-x coatings 50-300 nm in thickness were formed on carbon steel substrates by vacuum-arc deposition. Irradiation of the coated specimens was performed in a DC-60 heavy-ion accelerator by low-energy 4He+1, 4He+2 and 40Ar5+ ions and high-energy 40Ar5+ ions up to the fluence 1.0·1017 ion/cm2 at the irradiation temperature not higher than 150°C. It is shown that irradiation of the (Ti, Cr)N1-x coating surface by 4He+1, 4He+2 and 40Ar5+ ions with the energy 20 keV/charge does not give rise to any noticeable structural changes nor any surface blistering, while its irradiation by 40Ar5+ ions with the energy 1.50 MeV/amu causes blistering.

  7. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system.

    PubMed

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-01-01

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report (3)He/(4)He measurements in CO2-dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a (3)He/(4)He signature of at least 7.0 Ra (being Ra the (3)He/(4)He ratio of atmospheric He equal to 1.39×10(-6)), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like (3)He/(4)He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano. PMID:27311383

  8. Oxygen, hydrogen, and helium isotopes for investigating groundwater systems of the Cape Verde Islands, West Africa

    USGS Publications Warehouse

    Heilweil, V.M.; Solomon, K.D.; Gingerich, S.B.; Verstraeten, Ingrid M.

    2009-01-01

    Stable isotopes (??18O, ??2H), tritium (3H), and helium isotopes (3He, 4He) were used for evaluating groundwater recharge sources, flow paths, and residence times of three watersheds in the Cape Verde Islands (West Africa). Stable isotopes indicate the predominance of high-elevation precipitation that undergoes little evaporation prior to groundwater recharge. In contrast to other active oceanic hotspots, environmental tracers show that deep geothermal circulation does not strongly affect groundwater. Low tritium concentrations at seven groundwater sites indicate groundwater residence times of more than 50 years. Higher tritium values at other sites suggest some recent recharge. High 4He and 3He/4He ratios precluded 3H/3He dating at six sites. These high 3He/4He ratios (R/Ra values of up to 8.3) are consistent with reported mantle derived helium of oceanic island basalts in Cape Verde and provided end-member constraints for improved dating at seven other locations. Tritium and 3H/3He dating shows that S??o Nicolau Island's Ribeira Faj?? Basin has groundwater residence times of more than 50 years, whereas Fogo Island's Mosteiros Basin and Santo Ant??o Island's Ribeira Paul Basin contain a mixture of young and old groundwater. Young ages at selected sites within these two basins indicate local recharge and potential groundwater susceptibility to surface contamination and/or salt-water intrusion. ?? Springer-Verlag 2009.

  9. A theoretical approach to electromagnetic reactions in light nuclei

    NASA Astrophysics Data System (ADS)

    Xu, Tianrui; Miorelli, Mirko; Bacca, Sonia; Hagen, Gaute

    2016-03-01

    We briefly review the theory for electromagnetic reactions in light nuclei based on the coupled-cluster formulation of the Lorentz integral transform method. Results on photodisintegration reactions of 22O and 40Ca are reported and preliminary calculations on the Coulomb sum rule for 4He are discussed.

  10. Berkeley Experiments on Superfluid Macroscopic Quantum Effects

    SciTech Connect

    Packard, Richard

    2006-09-07

    This paper provides a brief history of the evolution of the Berkeley experiments on macroscopic quantum effects in superfluid helium. The narrative follows the evolution of the experiments proceeding from the detection of single vortex lines to vortex photography to quantized circulation in 3He to Josephson effects and superfluid gyroscopes in both 4He and 3He.

  11. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system.

    PubMed

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-06-17

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report (3)He/(4)He measurements in CO2-dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a (3)He/(4)He signature of at least 7.0 Ra (being Ra the (3)He/(4)He ratio of atmospheric He equal to 1.39×10(-6)), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like (3)He/(4)He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano.

  12. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system

    NASA Astrophysics Data System (ADS)

    Rizzo, Andrea; Caracausi, Antonio; Chavagnac, Valérie; Nomikou, Paraskevi; Polymenakou, Paraskevi; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain

    2016-04-01

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important ource of mantle-derived gases. These gases are fundamental for the comprehension of mantle characteristics in key sectors where subaerial volcanism is missing or strongly modified by mixing with crustal and atmospheric components. Though, the study of submarine volcanic areas remains a challenge due to their hazardousness and sea depth. Here, we report 3He/4He measurements in CO2-dominated gases discharged at 500 m below the sea level from the high-temperature (~220°C) hydrothermal system of Kolumbo submarine volcano, located 7 km northeast off Santorini Island in the central part of Hellenic Volcanic Arc (HVA). For the first time, we demonstrate that the mantle below Kolumbo and Santorini has a 3He/4He signature of at least 7.1 Ra (being Ra the 3He/4He ratio of atmospheric He equal to 1.39×10-6), 3 Ra units higher than actually known for Santorini gases-rocks. This isotopic ratio is also the highest measured across HVA and is indicative of the direct degassing of a MORB-like mantle through lithospheric faults or a possible slab tear. We finally highlight that the 3He/4He ratio has been increasing since 2010 (ΔRa=0.3), which implies an enhanced magmatic activity beneath Kolumbo.

  13. Ab initio calculations in three-body cluster systems

    SciTech Connect

    Romero-Redondo, C.; Navratil, P.; Quaglioni, S.

    2013-06-10

    In this work we briefly outline the extension of the ab initio no-core shell model/Resonating group method (NCSM/RGM) to three-body cluster states. We present the results for {sup 6}He ground state within a {sup 4}He+n+n cluster basis under this approach.

  14. The difference that linear energy transfer makes to precursors of DNA strand breaks

    SciTech Connect

    Milligan, J.R.; Aguilera, J.A.; Wu, C.C.L.; Ng, J.Y.Y.; Ward, J.F.

    1996-04-01

    Using agarose gel electrophoresis, we have measured the yields of DNA single- and double-strand breaks (SSBs and DSBs) for plasmid DNA irradiated in aerobic aqueous solution with either {sup 137}Cs {gamma} rays or {sup 4}He ions with a mean LET of 94 or 150 keV {mu}m{sup {minus}1}. The presence of dimethyl sulfoxide (DMSO) resulted in a decrease in the yields of both SSBs and DSBs, with a greater decrease being apparent for {gamma} irradiation than for {sup 4}He-ion irradiation. Irradiation by {sup 4}He ions in the presence of N-(2-thioethyl)-1,3-diaminopropane (WR-1065) resulted in a decrease in the yield of SSBs and a slightly larger decrease in the yield of DSBs. Together with results obtained previously, these observations suggest a substantial contribution to the formation of SSBs and DSBs by {sup 4}He ions by species containing at leas two radicals and more than two radicals, respectively. 16 refs., 8 figs., 1 tab.

  15. Optically pumped alkali laser and amplifier using helium-3 buffer gas

    DOEpatents

    Beach, Raymond J.; Page, Ralph; Soules, Thomas; Stappaerts, Eddy; Wu, Sheldon Shao Quan

    2010-09-28

    In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Other embodiments are also disclosed.

  16. CLUSTER STATES IN C-12 AND C-14

    SciTech Connect

    Freer, M.; Ashwood, N. I.; Curtis, N.; Malcolm, J.; Munoz-Britton, T.; Wheldon, C.; Ziman, A.; Carter, J.; Fujita, H.; Usman, I.; Buthelezi, Z.; Fortsch, S. V.; Neveling, R.; Perez, S. M.; Smit, F. D.; Fearick, R. W.; Papka, P.; Swartz, J. A.; Brown, S.; Catford, W.; Wilson, G.; Bardayan, Daniel W; Pain, Steven D; Chipps, K.; Grzywacz-Jones, K.; Soic, N.; Achouri, N. L.

    2010-07-01

    The cluster structure of 12C is explored and recent measurements of proton inelastic scattering, suggesting a 2+ state close to 9.6 MeV are presented. Resonant scattering studies of 10Be + 4He used to populate resonances in 14C are briefly discussed.

  17. CLUSTER STATES IN C-12 AND C-14

    SciTech Connect

    Freer, M.; Ashwood, N. I.; Curtis, N.; Malcolm, J.; Munoz-Britton, T.; Wheldon, C.; Ziman, A.; Carter, J.; Fujita, H.; Usman, I.; Buthelezi, Z.; Fortsch, S. V.; Neveling, R.; Perez, S. M.; Smit, F. D.; Fearick, R. W.; Papka, P.; Swartz, J. A.; Brown, S.; Catford, W.; Wilson, G.; Bardayan, Daniel W; Pain, Steven D; Chipps, K.; Grzywacz-Jones, K.; Soic, N.; Adekola, Aderemi S; Achouri, N. L.

    2010-01-01

    The cluster structure of 12C is explored and recent measurements of proton inelastic scattering, suggesting a 2+ state close to 9.6 MeV are presented. Resonant scattering studies of 10Be + 4He used to populate resonances in 14C are briefly discussed.

  18. Study of the high-j states in {sup 249}Cm.

    SciTech Connect

    Ahmad, I.

    1998-07-16

    The authors have performed the reaction {sup 248}Cm({sup 4}He, {sup 3}He) using 98.5-MeV alpha particles from the IUCF cyclotron to populate high-j states in {sup 249}Cm. A tentative assignment of the K{sub 17/2} component of the 1/2{sup +}[880] Nilsson state has been made.

  19. Psycho-linguistic and Pedagogical Aspects in the Bilingual Education of a Child of Pre-school Age.

    ERIC Educational Resources Information Center

    Zierer, Ernesto

    1974-01-01

    The subject of this study was a Peruvian child who learned German first and, from the age of 2 years and 10 months, was systematically exposed to Spanish. At the age of 4, he had mastered both German and Spanish to the same degree of phonic, morphological, and syntactic competence. Two weeks after the surgical removal of a brain tumor at 5 years…

  20. A model to explain the various paradoxes associated with mantle noble gas geochemistry

    PubMed Central

    Anderson, Don L.

    1998-01-01

    As a result of an energetic accretion, the Earth is a volatile-poor and strongly differentiated planet. The volatile elements can be accounted for by a late veneer (≈1% of total mass of the Earth). The incompatible elements are strongly concentrated into the exosphere (atmosphere, oceans, sediments, and crust) and upper mantle. Recent geochemical models invoke a large primordial undegassed reservoir with chondritic abundances of uranium and helium, which is clearly at odds with mass and energy balance calculations. The basic assumption behind these models is that excess “primordial” 3He is responsible for 3He/4He ratios higher than the average for midocean ridge basalts. The evidence however favors depletion of 3He and excessive depletion of 4He and, therefore, favors a refractory, residual (low U, Th) source Petrological processes such as melt-crystal and melt-gas separation fractionate helium from U and Th and, with time, generate inhomogeneities in the 3He/4He ratio. A self-consistent model for noble gases involves a gas-poor planet with trapping of CO2 and noble gases in the shallow mantle. Such trapped gases are released by later tectonic and magmatic processes. Most of the mantle was depleted and degassed during the accretion process. High 3He/4He gases are viewed as products of ancient gas exsolution stored in low U environments, rather than products of primordial reservoirs. PMID:9689038

  1. Helium isotopes at Rungwe Volcanic Province, Tanzania, and the origin of East African Plateaux

    NASA Astrophysics Data System (ADS)

    Hilton, D. R.; Halldórsson, S. A.; Barry, P. H.; Fischer, T. P.; de Moor, J. M.; Ramirez, C. J.; Mangasini, F.; Scarsi, P.

    2011-11-01

    We report helium isotope ratios (3He/4He) of lavas and tephra of the Rungwe Volcanic Province (RVP) in southern Tanzania. Values as high as 15RA (RA = air 3He/4He) far exceed typical upper mantle values, and are the first observation of plume-like ratios south of the Turkana Depression which separates the topographic highs of the Ethiopia and Kenya domes. The African Superplume - a tilted low-velocity seismic anomaly extending to the core-mantle boundary beneath southern Africa - is the likely source of these high 3He/4He ratios. High 3He/4He ratios at RVP together with similarly-high values along the Main Ethiopian Rift and in Afar provide compelling evidence that the African Superplume is a feature that extends through the 670-km seismic discontinuity and provides dynamic support - either as a single plume or via multiple upwellings - for the two main topographic features of the East Africa Rift System as well as heat and mass to drive continuing rift-related magmatism.

  2. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system

    PubMed Central

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N.; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-01-01

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report 3He/4He measurements in CO2–dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a 3He/4He signature of at least 7.0 Ra (being Ra the 3He/4He ratio of atmospheric He equal to 1.39×10−6), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like 3He/4He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano. PMID:27311383

  3. Charge and parity projected relativistic mean field model with pion for finite nuclei

    SciTech Connect

    Ogawa, Yoko; Toki, Hiroshi; Tamenaga, Setsuo; Sugimoto, Satoru; Ikeda, Kiyomi

    2006-03-15

    We construct a new relativistic mean field model by explicitly introducing a {pi}-meson mean field with charge number and parity projection. We call this model the charge and parity projected relativistic mean field (CPPRMF) model. We take the chiral {sigma} model Lagrangian for the construction of finite nuclei. We apply this framework first for the {sup 4}He nucleus as a pilot case and study the role of the {pi}-meson field on the structure of nuclei. We demonstrate that it is essential to solve the mean field equation with the variation introduced after the projection in order to take the pionic correlations into account explicitly. We study the ground-state properties of {sup 4}He by varying several parameters, such as the {sigma}-meson mass and the {omega}-meson coupling constant. We are able to construct a good ground state for {sup 4}He. A depression appears in the central region of the density distribution, and the second maximum and the position of the dip in the form factor of {sup 4}He are naturally obtained in the CPPRMF model.

  4. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system

    NASA Astrophysics Data System (ADS)

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N.; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-06-01

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report 3He/4He measurements in CO2–dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a 3He/4He signature of at least 7.0 Ra (being Ra the 3He/4He ratio of atmospheric He equal to 1.39×10‑6), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like 3He/4He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano.

  5. On the connection between the 3HE-enrichment and spectral index of solar energetic particles

    NASA Technical Reports Server (NTRS)

    Kocharov, L. G.; Dvoryanchikov, Y. V.

    1985-01-01

    A model is presented which explains the observed tendency of events with large 3He/4He ratios to have steeper spectra. In this model preferential injection of 3He, acceleration by Alfven waves and Coulomb deceleration of ions are considered simultaneously. The observed tendency may be obtained as a result of competition between injection and acceleration processes.

  6. Ground-Water Temperature, Noble Gas, and Carbon Isotope Data from the Espanola Basin, New Mexico

    USGS Publications Warehouse

    Manning, Andrew H.

    2009-01-01

    Ground-water samples were collected from 56 locations throughout the Espanola Basin and analyzed for general chemistry (major ions and trace elements), carbon isotopes (delta 13C and 14C activity) in dissolved inorganic carbon, noble gases (He, Ne, Ar, Kr, Xe, and 3He/4He ratio), and tritium. Temperature profiles were measured at six locations in the southeastern part of the basin. Temperature profiles suggest that ground water generally becomes warmer with distance from the mountains and that most ground-water flow occurs at depths 50 years old, consistent with the 14C ages. Terrigenic He (Heterr) concentrations in ground water are high (log Delta Heterr of 2 to 5) throughout much of the basin. High Heterr concentrations are probably caused by in situ production in the Tesuque Formation from locally high concentrations of U-bearing minerals (Northeast zone only), or by upward diffusive/advective transport of crustal- and mantle-sourced He possibly enhanced by basement piercing faults, or by both. The 3He/4He ratio of Heterr (Rterr) is commonly high (Rterr/Ra of 0.3-2.0, where Ra is the 3He/4He ratio in air) suggesting that Espanola Basin ground water commonly contains mantle-sourced He. The 3He/4He ratio of Heterr is generally the highest in the western and southern parts of the basin, closest to the western border fault system and the Quaternary to Miocene volcanics of the Jemez Mountains and Cerros del Rio.

  7. A High-Resolution Thermometer for the Range 0.75-1.0 K

    NASA Technical Reports Server (NTRS)

    Panek, J.; Nash, A.; Larson, M.; Mulders, N.

    1999-01-01

    We report on a new high-resolution thermometer (HRT) for use near the tricritical point in 3He-4He mixtures. It is based on an existing HRT design that uses a DC-SQUID to detect the magnetization of a paramagnetic sensing element.

  8. Measurements with a recuperative superfluid Stirling refrigerator

    SciTech Connect

    Watanabe, A.; Swift, G.W.; Brisson, J.G.

    1995-08-01

    A superfluid Stirling refrigerator cooled to 168 mK using a 4.9% {sup 3}He- {sup 4}He mixture and exhausting its waste heat at 383 mK. Cooling power versus temperature and speed is presented for 4.9%, 17%, and 36% mixtures. At the highest concentration, a dissipation mechanism of unknown origin is observed.

  9. A recuperative superfluid stirling refrigerator

    SciTech Connect

    Brisson, J.G.; Swift, G.W.

    1993-07-01

    A superfluid Stirling refrigerator has been built with a counterflow heat exchanger serving as a recuperative regenerator. It has achieved temperatures of 296 mK with a 4% {sup 3}He-{sup 4}He mixture. Cooling power versus temperature and speed is presented for a 6.6% mixture.

  10. The Upper Limit on 3He Fluence in Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Ho, G. C.; Roelof, E. C.; Mason, G. M.

    2005-03-01

    We investigated 201 3He-rich (3He/4He > 0.004 at 0.2-2.0 MeV nucleon-1) solar energetic particle (SEP) events from 1997 September through 2003 December using the Ultra Low Energy Isotope Spectrometer on the A dvanced Composition E xplorer. Both ``impulsive'' (flare-related) and ``gradual'' (CME-related) events are included. The 3He fluences varied only by a factor of 100 above our instrument sensitivity threshold, while the 4He fluences varied by factor of 10,000 above the same threshold. Moreover, there appears to be no significant correlation between the 3He and 4He fluences. We find it striking that with more than 6 years of continuous SEP data, we could not find any SEP event that has 3He fluence higher than 2.0×105 particles (cm2 sr MeV nucleon-1)-1, while the largest 4He fluence observed was 7.0×107 particles (cm2 sr MeV nucleon-1)-1. To the approximation that the event fluence is to first order proportional the number of particles released from the Sun, the observed upper limit for the 3He fluence seems to indicate that only a limited number of 0.2-2 MeV nucleon-1 3He can be released from the Sun in an SEP event.

  11. IPNS-I chopper spectrometers

    SciTech Connect

    Price, D.L.; Carpenter, J.M.; Pelizzari, C.A.; Sinha, S.K.; Bresof, I.; Ostrowski, G.E.

    1982-01-01

    We briefly describe the layout and operation of the two chopper experiments at IPNS-I. The recent measurement on solid /sup 4/He by Hilleke et al. provides examples of time-of-flight data from the Low Resolution Chopper Spectrometer.

  12. Nuclear and partonic dynamics in high energy elastic nucleus-nucleus scattering

    NASA Astrophysics Data System (ADS)

    Małecki, Andrzej

    1991-10-01

    A hybrid description of diffraction which combines a geometrical modeling of multiple scattering with many-channel effects resulting from intrinsic dynamics on the nuclear and subnuclear level is presented. The application to 4-4He elastic scattering is satisfactory. Our analysis suggests that, at large momentum transfers, the parton constituents of nucleons immersed in nuclei are deconfined.

  13. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    SciTech Connect

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  14. Ultimate Temperature of Pulse Tube Cryocoolers

    NASA Technical Reports Server (NTRS)

    Kittel, Peter

    2009-01-01

    An ideal pulse tube cryocooler using an ideal gas can operate at any temperature. This is not true for real gases. The enthalpy flow resulting from the real gas effects of 3He, 4He, and their mixtures in ideal pulse tube cryocoolers puts limits on the operating temperature of pulse tube cryocoolers. The discussion of these effects follows a previous description of the real gas effects in ideal pulse tube cryocoolers and makes use of models of the thermophysical properties of 3He and 4He. Published data is used to extend the analysis to mixtures of 3He and 4He. The analysis was done for pressures below 2 MPa and temperatures below 2.5 K. Both gases and their mixtures show low temperature limits for pulse tube cryocoolers. These limits are in the 0.5-2.2 K range and depend on pressure and mixture. In some circumstances, even lower temperatures may be possible. Pulse tube cryocoolers using the ha-fluid properties of dilute 3He in superfluid 4He appear to have no limit.

  15. The emission probabilities of long range alpha particles from even-even 244-252Cm isotopes

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Krishnan, Sreejith; Priyanka, B.

    2014-10-01

    The alpha accompanied cold ternary fission of even-even 244Cm, 246Cm, 248Cm, 250Cm and 252Cm isotopes has been studied by taking the interacting barrier as the sum of the Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold reaction valley plot and by calculating the relative yield for the charge minimized fragments. In the alpha accompanied ternary fission of the 244Cm isotope, the highest yield is found for the fragment combination 110Ru+4He+130Sn, which possess near doubly magic nuclei 130Sn. For the ternary fission of 246Cm, 248Cm, 250Cm and 252Cm isotopes with 4He as the light charged particle, the highest yield is obtained for the fragment combination with doubly magic nuclei 132Sn as the heavier fragment. The emission probabilities and kinetic energies of long range alpha particles have been computed for the 242,244,246,248Cm isotopes and are found to be in good agreement with the experimental data. The relative yields for the 4He accompanied ternary fission (equatorial and collinear) of 242-252Cm isotopes are compared with the corresponding yield for binary fission. The effect of deformation and orientation of fragments in the 4He accompanied ternary fission of 244-252Cm isotopes are studied. Our study reveals that the ground state deformation has as an important role in the alpha accompanied ternary fission as that of the shell effect.

  16. Source of radiogenic helium 4 in shallow aquifers: Implications for dating young groundwater

    NASA Astrophysics Data System (ADS)

    Solomon, D. K.; Hunt, A.; Poreda, R. J.

    Radiogenic helium 4 (4Herad) has been used in numerous studies as a tracer of groundwater age in the range of 103-108 years. We have measured 4Herad along shallow groundwater flow paths at a variety of hydrogeologically distinct sites and postulate its use for dating groundwater as young as 101 years. Groundwater travel times and fluid velocities are particularly well documented at one site in northern Ontario because of detailed profiling of tritium, 3H/3He ratios, and chlorofluorocarbons (CFCs). Metamorphic rocks of the Canadian Shield (>1 Ga) that contain large quantities of 4He are the protolith of this unconsolidated aquifer and observed 4Herad values increase linearly with distance along a flow path and with increasing groundwater age. A solute transport model suggests that the aquifer solids are the source of 4Herad as vertical fluid velocities are too great to allow upward diffusion of 4Herad from the underlying shield rocks. The apparent rate of 4Herad release is 130 μcm3m-3yr-1 and is 300 times greater than can be supported by the in situ decay of U and Th series nuclides (i.e., the ``steady state'' approximation). Laboratory release experiments (conducted by sequentially heating the aquifer solids, measuring the amount of 4He released, and then extrapolating release rates to the in situ temperature) agree well with the field results and suggest that diffusion from aquifer solids is the source of 4Herad. The combined laboratory and field release data yield 4He diffusion coefficients that exhibit an Arrhenius temperature dependence that is similar to 4He diffusion in quartz reported by other researchers. The 4Herad release rate at the Ontario site is extraordinarily similar to sites in Tennessee, Nebraska, and Germany in spite of major hydrogeologic differences. A model of 4He diffusion from spherical grains suggests that aquifer solids derived from old protoliths will release 4He at rates greater than supported by U/Th production for up to 50 million

  17. Noble gases in CH 4-rich gas fields, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Hiyagon, H.; Kennedy, B. M.

    1992-04-01

    The elemental and isotopic compositions of helium, neon, argon, and xenon in twenty-one CH 4-rich natural gas samples from Cretaceous and Devonian reservoirs in the Alberta, Canada, sedimentary basin were measured. In all but a few cases, radiogenic ( 4He, 40Ar, and 131-136Xe) and nucleogenic ( 21,22Ne) isotopes dominated. Based solely on the noble gas composition, two types of natural gas reservoirs are identified. One (Group B) is highly enriched in radiogenic-nucleogenic noble gases and varies little in composition: 3He /4He = 1.5 ± 0.5 × 10 -8, 40Ar /36Ar = 5000-6500 , 40∗Ar /4He = 0.10 , 136∗Xe /4He ~ 0.7 × 10 -9, and 21∗Ne /22∗Ne = 0.452 ± 0.041 (∗ denotes radiogenic or nucleogenic origin; all 4He is radiogenic). High nitrogen content with 4He /N 2 ~ 0.06 is also characteristic of Group B samples. The remaining samples (Group A) contain a radiogenic-nucleogenic component with a different composition and, relative to Group B samples, the extent of enrichment in this component is less and more variable: 3He /4He = 10-70 × 10 -8, 40Ar /36Ar < 1550 , and 40∗Ar /4He ~ 0.25 . The composition of Group B radiogenic-nucleogenic noble gases is consistent with production in crust of average composition. Enrichment in Group B noble gases and nitrogen increases with proximity to the underlying Precambrian basement, consistent with a present-day mass flux into the overlying sedimentary basin. Inferred 40∗Ar /136∗Xe 4He ratios imply a basement source enriched in thorium relative to uranium and potassium (Th/U > 20). Combined, the overall lower total radiogenic-nucleogenic content of Group A reservoirs, the greater variability in composition, and the appearance of Group A noble gases in reservoirs higher in the sedimentary sequence relative to the underlying basement implies that the Group A radiogenic-nucleogenic noble gases are indigenous to the sediments. The most interesting aspect of the Group A noble gases are the very high 3He /4He ratios; ~ 10

  18. The helium paradoxes

    PubMed Central

    Anderson, Don L.

    1998-01-01

    The ratio 3He/4He (R) plays a central role in models of mantle evolution that propose an undegassed lower mantle, rich in the primordial isotope 3He. A large primordial volatile-rich reservoir, a feature of recent models, is inconsistent with high-temperature accretion and with estimates of crustal and bulk Earth chemistry. High R can alternatively reflect high integrated 3He/(U+Th) ratios or low 4He abundances, as expected in refractory portions of the upper mantle. I show that high R materials are gas-poor and are deficient in radiogenic 4He compared with midocean ridge basalts. The seemingly primitive (i.e., high R) signatures in “hotspot” magmas may be secondary, derived from CO2-rich gases, or residual peridotite, a result of differential partitioning of U and He into magmas. A shallow and low 3He source explains the spatial variability and the temporal trends of R in ocean islands and is consistent with a volatile-poor planet. A shallow origin for the “primitive” He signature in ocean island basalts, such as at Loihi, reconciles the paradoxical juxtaposition of crustal, seawater, and atmospheric signatures with inferred “primitive” characteristics. High 238U/204Pb components in ocean island basalts are generally attributed to recycled altered oceanic crust. The low 238U/3He component may be in the associated depleted refractory mantle. High 3He/4He ratios are due to low 4He, not excess 3He, and do not imply or require a deep or primordial or undegassed reservoir. 40Ar in the atmosphere also argues against such models. PMID:9560186

  19. The helium paradoxes.

    PubMed

    Anderson, D L

    1998-04-28

    The ratio 3He/4He (R) plays a central role in models of mantle evolution that propose an undegassed lower mantle, rich in the primordial isotope 3He. A large primordial volatile-rich reservoir, a feature of recent models, is inconsistent with high-temperature accretion and with estimates of crustal and bulk Earth chemistry. High R can alternatively reflect high integrated 3He/(U+Th) ratios or low 4He abundances, as expected in refractory portions of the upper mantle. I show that high R materials are gas-poor and are deficient in radiogenic 4He compared with midocean ridge basalts. The seemingly primitive (i.e., high R) signatures in "hotspot" magmas may be secondary, derived from CO2-rich gases, or residual peridotite, a result of differential partitioning of U and He into magmas. A shallow and low 3He source explains the spatial variability and the temporal trends of R in ocean islands and is consistent with a volatile-poor planet. A shallow origin for the "primitive" He signature in ocean island basalts, such as at Loihi, reconciles the paradoxical juxtaposition of crustal, seawater, and atmospheric signatures with inferred "primitive" characteristics. High 238U/204Pb components in ocean island basalts are generally attributed to recycled altered oceanic crust. The low 238U/3He component may be in the associated depleted refractory mantle. High 3He/4He ratios are due to low 4He, not excess 3He, and do not imply or require a deep or primordial or undegassed reservoir. 40Ar in the atmosphere also argues against such models. PMID:9560186

  20. Fullerenes, Noble Gases and the Flux of Extraterrestrial Debris to

    NASA Astrophysics Data System (ADS)

    Becker, Luann; Poreda, Robert; Bunch, Ted

    The discovery of fullerenes in deposits associated with two separate impact events involving a large bolide with the Earth suggests that these carbon (C) molecules may also be an indicator of extraterrestrial (ET) events over geologic time. Fullerenes were detected in carbon-rich breccias (Onaping Fm.) associated with the 1.85 byr Sudbury Crater (Becker et al., Science 265, 1994) and in clay sediments within the 65 myr old Cretaceous/Tertiary (K/T) boundary (Heymann et al., Science 265, 1994). To determine the origin of the Sudbury fullerenes, we searched for noble gases trapped inside the fullerene molecules (Saunders et al., Science 259, 1993). The Sudbury fullerenes contain trapped 3He/4He ratios (~5.5 times 10^{-4}) similar to those found in meteorites and some interplanetary dust particles (Becker et al., Science 272, 1996). Preliminary measurements of He in a continental K/T fullerene residue from Raton Basin (Colorado) revealed ^3He/^4He ratios some 100 times above air. A marine K/T residue from Stevns Klint, (Denmark) revealed ^3He/^4He ratios several thousand times above air in the high temperature fraction! We attribute the anomalously high ^3He/^4He ratios and high ^3He concentration in Stevns Klint to the abundance of higher fullerenes in the residue. The high ^3He/^4He ratio in the K/T fullerenes suggests that they were present in the bolide and somehow survived the impact event. Confirmation of these results could have broad implications concerning the importance of exogenous delivery in providing carbon, volatiles and perhaps other organics to the early Earth's crustal reservoir.

  1. Helium isotopes in ferromanganese crusts from the central Pacific Ocean

    USGS Publications Warehouse

    Basu, S.; Stuart, F.M.; Klemm, V.; Korschinek, G.; Knie, K.; Hein, J.R.

    2006-01-01

    Helium isotopes have been measured in samples of two ferromanganese crusts (VA13/2 and CD29-2) from the central Pacific Ocean. With the exception of the deepest part of crust CD29-2 the data can be explained by a mixture of implanted solar- and galactic cosmic ray-produced (GCR) He, in extraterrestrial grains, and radiogenic He in wind-borne continental dust grains. 4He concentrations are invariant and require retention of less than 12% of the in situ He produced since crust formation. Loss has occurred by recoil and diffusion. High 4He in CD29-2 samples older than 42 Ma are correlated with phosphatization and can be explained by retention of up to 12% of the in situ-produced 4He. 3He/4He of VA13/2 samples varies from 18.5 to 1852 Ra due almost entirely to variation in the extraterrestrial He contribution. The highest 3He/4He is comparable to the highest values measured in interplanetary dust particles (IDPs) and micrometeorites (MMs). Helium concentrations are orders of magnitude lower than in oceanic sediments reflecting the low trapping efficiency for in-falling terrestrial and extraterrestrial grains of Fe-Mn crusts. The extraterrestrial 3He concentration of the crusts rules out whole, undegassed 4–40 μm diameter IDPs as the host. Instead it requires that the extraterrestrial He inventory is carried by numerous particles with significantly lower He concentrations, and occasional high concentration GCR-He-bearing particles.

  2. Two-phase Neogene extension in the northwestern basin and range recorded in a single thermochronology sample

    USGS Publications Warehouse

    Colgan, J.P.; Shuster, D.L.; Reiners, P.W.

    2008-01-01

    We use a combination of apatite 4He/3He, (U-Th)/ He, and fission-track thermochronology to date slip on the Surprise Valley fault in northeastern California by analyzing a single sample from the Warner Range in the footwall of the fault. This sample, a granitic clast from a conglomerate, yielded a fission-track age of 11.6 ?? 2.8 Ma and a (U-Th)/He age of 3.02 ?? 0.52 Ma. Geologic relationships indicate that this sample was buried to a depth of ???3.3 km prior to exhumation during slip on the Surprise Valley fault. Fission-track age and length data indicate that the sample was fully reset (>120 ??C) prior to exhumation, which began sometime after 14 Ma. A single aliquot of nine apatite grains was step-heated for 4He/3He analysis; modeling of the resulting 4He distribution indicates that cooling from <80 ??C to ???20 ??C occurred between 3 and 1 Ma. Interconsistent time-temperature (t-T) solutions to the combined 4He/3He, (U-Th)/He, and fission-track data require two distinct periods of cooling, consistent with non-continuous slip on the Surprise Valley fault. Early cooling and fault slip took place between 14 and 8 Ma, followed by more recent fault slip ca. 3 Ma. This timing is consistent with both local geologic relationships and with the regional timing of faulting along the western margin of the Basin and Range Province. These data demonstrate the resolving power of combined fission-track, (U-Th)/He, and 4He/3He thermochronometric data to extract low-temperature t-T information from a single sample close to Earth's surface. ?? 2008 The Geological Society of America.

  3. Two-phase Neogene extension of the northwestern Basin and Range deduced from thermochronology of a single sample

    NASA Astrophysics Data System (ADS)

    Colgan, J. P.; Shuster, D. L.; Reiners, P. W.

    2007-12-01

    We use a combination of apatite 4He/3He, (U-Th)/He, and fission-track thermochronology to date slip on the Surprise Valley Fault in northeastern California by analyzing a single granitic boulder from a conglomerate lens near the base of the adjacent Warner Range. Apatite from this sample yielded a fission-track age of 11.6 ± 1.4 Ma and a (U-Th)/He age of 3.12 ± 0.2 Ma. Regional geologic relationships indicate that this sample was buried to a depth of about 3.3 km prior to exhumation during slip on the Surprise Valley Fault. Apatite fission-track data indicate that the sample was fully reset (>120°C) prior to exhumation, which began sometime after 14 Ma. A single aliquot of nine apatite grains was step-heated for 4He/3He analysis; modeling of the resulting 4He distribution indicates cooling from >80°C to ~20°C between 3 and 1 Ma. Internally consistent time-temperature (t-T) solutions to the combined 4He/3He, (U-Th)/He, and fission-track data require two periods of cooling, consistent with non-continuous slip on the Surprise Valley Fault. Early cooling and fault slip took place between 14 and 8 Ma, and was followed by a more recent pulse of cooling at about 3 Ma. This timing is consistent with both local geologic relationships and with the regional timing of faulting along the western margin of the Basin and Range. These data demonstrate the resolving power of combined fission-track, (U-Th)/He, and 4He/3He thermochronometric data to extract high-resolution and ultra low temperature t-T information from a single sample close to the earth's surface.

  4. Constraints on mantle source and interactions from He-Sr isotope variation in Italian Plio-Quaternary volcanism

    NASA Astrophysics Data System (ADS)

    Martelli, M.; Nuccio, P. M.; Stuart, F. M.; di Liberto, V.; Ellam, R. M.

    2008-02-01

    Helium isotope ratios of olivine and pyroxene phenocrysts from Plio-Quaternary volcanic rocks from southern Italy (seven Aeolian Islands, Mt. Vulture, Etna, Ustica, and Pantelleria) range from 2.3 to 7.1 Ra. Importantly, the phenocryst 3He/4He correlate well with whole rock Sr isotopic composition (0.70309-0.70711), reflecting the mixing of two sources. A significant contribution of He from crustal contamination is recorded only occasionally (e.g., pyroxenes from Vulcano). When merged with data from the Roman Comagmatic Province, a remarkably strong near-linear He-Sr isotope correlation is apparent. The general northward decrease in 3He/4He corresponds to an increase in 87Sr/86Sr (and a decrease in 143Nd/144Nd and 206Pb/204Pb) that is due to increasing metasomatic enrichment of the mantle wedge via subduction of the Ionian-Adriatic plate. Calculations based on the ingrowth of 4He in the wedge and on the 4He content of the subducting crust show that mechanisms of enrichment in radiogenic He are effective only if the wedge is strongly depleted in He relative to best estimates of the depleted mantle. This can be accommodated if the process of metasomatism by the subduction fluids depletes the mantle wedge. The 3He/4He of Pantelleria, Etna, Iblei, Ustica, Alicudi, and Filicudi basalts (7.0 ± 0.6 Ra) define the mantle composition least affected by subduction-related metasomatism. Although these volcanoes are from a variety of tectonic regimes (subduction-related, intraplate, rifting), their similarities suggest a common origin of geochemical features. Their characteristics are consistent with a HIMU-type mantle that either is younger than the Cook-Austral island end-member or has a lower 238U/204Pb.

  5. Helium measurements of pore-fluids obtained from SAFOD drillcore

    SciTech Connect

    Ali, S.; Stute, M.; Torgersen, T.; Winckler, G.; Kennedy, B.M.

    2010-04-15

    {sup 4}He accumulated in fluids is a well established geochemical tracer used to study crustal fluid dynamics. Direct fluid samples are not always collectable; therefore, a method to extract rare gases from matrix fluids of whole rocks by diffusion has been adapted. Helium was measured on matrix fluids extracted from sandstones and mudstones recovered during the San Andreas Fault Observatory at Depth (SAFOD) drilling in California, USA. Samples were typically collected as subcores or from drillcore fragments. Helium concentration and isotope ratios were measured 4-6 times on each sample, and indicate a bulk {sup 4}He diffusion coefficient of 3.5 {+-} 1.3 x 10{sup -8} cm{sup 2}s{sup -1} at 21 C, compared to previously published diffusion coefficients of 1.2 x 10{sup -18} cm{sup 2}s{sup -1} (21 C) to 3.0 x 10{sup -15} cm{sup 2}s{sup -1} (150 C) in the sands and clays. Correcting the diffusion coefficient of {sup 4}He{sub water} for matrix porosity ({approx}3%) and tortuosity ({approx}6-13) produces effective diffusion coefficients of 1 x 10{sup -8} cm{sup 2}s{sup -1} (21 C) and 1 x 10{sup -7} (120 C), effectively isolating pore fluid {sup 4}He from the {sup 4}He contained in the rock matrix. Model calculations indicate that <6% of helium initially dissolved in pore fluids was lost during the sampling process. Complete and quantitative extraction of the pore fluids provide minimum in situ porosity values for sandstones 2.8 {+-} 0.4% (SD, n=4) and mudstones 3.1 {+-} 0.8% (SD, n=4).

  6. Similarities and differences between the solar wind light noble gas compositions determined on Apollo 15 SWC foils and on NASA Genesis targets

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Bochsler, P.; Bühler, F.; Heber, V. S.; Grimberg, A.; Baur, H.; Horstmann, M.; Bischoff, A.; Wieler, R.

    2015-10-01

    We compare the solar wind (SW) He, Ne, and Ar compositions collected during the Apollo Solar Wind Composition (SWC) experiments (1969-1972; Al- & Pt-foils) and the Genesis mission (2002-2004; so-called DOS targets considered here). While published SW 20Ne/22Ne and 36Ar/38Ar ratios of both data sets agree, differences exist in the 4He/3He, 4He/20Ne, and 20Ne/36Ar ratios. However, 20Ne/36Ar ratios from Apollo-16 Pt-foils, exclusively adopted as SW values by the SWC team, are consistent with the Genesis results. We investigate if the differences indicate a variability of the SW over the course of about 30 yr, or systematic biases of the two data sets, which were collected in different environments and measured several decades apart in different laboratories (University of Bern; ETH Zurich). New measurements of Apollo-15 SWC aluminum foils in Zurich generally agree with the original measurements performed in Bern. Zurich samples show slightly lower 4He concentrations suggesting a few percent of diffusive loss of 4He during storage of the foils. A 3% difference between the He isotopic ratios measured in Bern and in Zurich possibly represents an analytical bias between the laboratories. The low SW 4He/20Ne and 20Ne/36Ar ratios in Apollo-15 Al-foils compared to Genesis data are consistent with a mixture of Genesis-like SW and noble gases from small amounts of lunar dust. Our data suggest that the mean SW He, Ne, and Ar isotopic and elemental compositions have not significantly changed between the overall Apollo and Genesis mission collection periods.

  7. Superfluid Stirling refrigerator with a counterflow regenerator

    SciTech Connect

    Brisson, J.G.; Swift, G.W.

    1992-01-01

    The superfluid Stirling refrigerator (SSR) uses a [sup 3]He-[sup 4]He liquid mixture as a working fluid. It operates at temperatures below 2 K where the [sup 4]He component of the working fluid is superfluid. The [sup 3]He component of the working fluid, to first approximation, behaves thermodynamically like an ideal gas in the inert background of superfluid [sup 4]He. Using pistons equipped with a superleak bypass, it is possible to expand and compress the [sup 3]He solute gas.'' The SSR is a Stirling machine equipped with these superleaked'' pistons to take advantage of the properties of the [sup 3]He solute to cool below 1 K. The proof of principle was shown by Kotsubo and Swift in 1990. There are three other techniques for cooling below 1 K: (1) the [sup 3]He-[sup 4]He dilution refrigerator which utilizes the endothermic heat of mixing of [sup 3]He into [sup 4]He to reach temperatures below 0.010 K; (2) the evaporation of [sup 3]He which can reach temperatures of 0.3 K; and, (3) adiabatic demagnetization of a paramagnetic salt. There are several advantages of the SSR over each of the other techniques. The power consumption of a dilution refrigerator is typically on the order of kilowatts; whereas, the SSR consumes hundreds of watts. The SSR has the potential to cool below 0.3 K and out-perform the evaporative [sup 3]He refrigerator. Adiabatic demagnetization often requires magnetic shielding between the refrigerator and the object to be cooled; obviously, the SSR requires no such shielding. There is an interest in developing subkelvin cryocoolers for satellite-borne X-ray and infrared detectors. In space applications, the power consumption of an SSR can be reduced to tens of watts. This coupled with the SSR's insensitivity to a zero G environment makes it an attractive option to cool detectors in space.

  8. Non-equilibrium degassing and a primordial source for helium in ocean-island volcanism.

    PubMed

    Gonnermann, Helge M; Mukhopadhyay, Sujoy

    2007-10-25

    Radioactive decay of uranium and thorium produces 4He, whereas 3He in the Earth's mantle is not produced by radioactive decay and was only incorporated during accretion-that is, it is primordial. 3He/4He ratios in many ocean-island basalts (OIBs) that erupt at hotspot volcanoes, such as Hawaii and Iceland, can be up to sixfold higher than in mid-ocean ridge basalts (MORBs). This is inferred to be the result of outgassing by melt production at mid-ocean ridges in conjunction with radiogenic ingrowth of 4He, which has led to a volatile-depleted upper mantle (MORB source) with low 3He concentrations and low 3He/4He ratios. Consequently, high 3He/4He ratios in OIBs are conventionally viewed as evidence for an undegassed, primitive mantle source, which is sampled by hot, buoyantly upwelling deep-mantle plumes. However, this conventional model provides no viable explanation of why helium concentrations and elemental ratios of He/Ne and He/Ar in OIBs are an order of magnitude lower than in MORBs. This has been described as the 'helium concentration paradox' and has contributed to a long-standing controversy about the structure and dynamics of the Earth's mantle. Here we show that the helium concentration paradox, as well as the full range of noble-gas concentrations observed in MORB and OIB glasses, can self-consistently be explained by disequilibrium open-system degassing of the erupting magma. We show that a higher CO2 content in OIBs than in MORBs leads to more extensive degassing of helium in OIB magmas and that noble gases in OIB lavas can be derived from a largely undegassed primitive mantle source.

  9. The helium paradoxes.

    PubMed

    Anderson, D L

    1998-04-28

    The ratio 3He/4He (R) plays a central role in models of mantle evolution that propose an undegassed lower mantle, rich in the primordial isotope 3He. A large primordial volatile-rich reservoir, a feature of recent models, is inconsistent with high-temperature accretion and with estimates of crustal and bulk Earth chemistry. High R can alternatively reflect high integrated 3He/(U+Th) ratios or low 4He abundances, as expected in refractory portions of the upper mantle. I show that high R materials are gas-poor and are deficient in radiogenic 4He compared with midocean ridge basalts. The seemingly primitive (i.e., high R) signatures in "hotspot" magmas may be secondary, derived from CO2-rich gases, or residual peridotite, a result of differential partitioning of U and He into magmas. A shallow and low 3He source explains the spatial variability and the temporal trends of R in ocean islands and is consistent with a volatile-poor planet. A shallow origin for the "primitive" He signature in ocean island basalts, such as at Loihi, reconciles the paradoxical juxtaposition of crustal, seawater, and atmospheric signatures with inferred "primitive" characteristics. High 238U/204Pb components in ocean island basalts are generally attributed to recycled altered oceanic crust. The low 238U/3He component may be in the associated depleted refractory mantle. High 3He/4He ratios are due to low 4He, not excess 3He, and do not imply or require a deep or primordial or undegassed reservoir. 40Ar in the atmosphere also argues against such models.

  10. Helium isotope studies in the Mojave Desert, California: Implications for groundwater chronology and regional seismicity

    USGS Publications Warehouse

    Kulongoski, J.T.; Hilton, David R.; Izbicki, J.A.

    2003-01-01

    We report helium isotope and concentration results for groundwaters from the western Mojave River Basin (MRB), 130 km east of Los Angeles, CA. The basin lies adjacent to the NW-SE trending San Andreas Fault (SAF) system. Samples were collected along two groundwater flowpaths that originate in the San Gabriel Mountains and discharge to the Mojave River located ???32 km to the northeast. Additional groundwater samples were collected from Mojave River Deposits underlying the Mojave River. The primary objective of this study is to identify and quantify crustal and mantle helium contributions to the regional groundwater system. A total of 27 groundwaters, sampled previously for chemistry and isotope systematics (including 14C activity) have measured helium concentrations that increase along flowpaths from 9.9??10-8 to 1.0??10-4 cm3 STP g-1 H2O. Concomitantly, 3He/4He ratios decrease from 0.84RA to 0.11RA (RA equals the 3He/4He ratio in air=1.4??10-6). We did not record 3He/4He ratios equivalent to crustal-production values (???0.02RA) in any sample. Dissolved helium concentrations were resolved into components associated with solubility equilibration, air entrainment, mantle-derivation, in-situ production within the aquifer, and extraneous crustal fluxes. All samples contained the first four components, but only older samples had the superimposed effects of helium derived from a crustal flux. The radiogenic He component has chronological significance, and good concordance between 4He and 14C ages for younger groundwaters (<25,000 year) demonstrates the integrity of the 4 He-chronometer in this setting. Helium-rich waters could also be dated with the 4He technique, but only by first isolating the whole crustal flux (3-10??10-6 cm3 STP cm-2 year-1). Mantle-derived 3He (3Hem) is present in all MRB samples irrespective of distance from the SAF. However, regional-aquifer groundwaters near the terminus of the flowpath have a significantly greater content of mantle-derived 3He

  11. Groundwater age investigation of eskers in the Amos region, Quebec, Canada

    NASA Astrophysics Data System (ADS)

    Boucher, Christine; Pinti, Daniele L.; Roy, Martin; Castro, M. Clara; Cloutier, Vincent; Blanchette, Daniel; Larocque, Marie; Hall, Chris M.; Wen, Tao; Sano, Yuji

    2015-05-01

    Noble gases, in particular 3He/4He (R) ratios, were measured together with tritium activity in groundwater from eskers and moraines of the Abitibi-Temiscamingue region of northwestern Quebec (eastern Canada). These high-latitude glaciofluvial landforms contain precious freshwater resources that need to be quantified. Here we provide estimates of residence time for groundwater in glaciofluvial sediments forming the Saint-Mathieu-Berry (SMB) and Barraute eskers, the Harricana moraine and in the underlying fractured bedrock aquifer. The 3He/4He ratios range from 0.224 ± 0.012 to 1.849 ± 0.036Ra, where Ra is the atmospheric 3He/4He ratio (1.386 × 10-6). These results suggest the occurrence of 3He produced by decay of tritium and terrigenic 4He produced by decay of U and Th. Calculated 3H/3He apparent ages of groundwater from the SMB esker and the Harricana moraine range from 6.6 ± 1.1 a to 32 ± 7.4 a. Terrigenic 4He (4Heterr) was found in the deeper wells of the SMB esker and in the wells tapping water from the deeper fractured aquifer located below the eskers and moraines and confined by postglacial clays. The amount of 4Heterr ranges from 3.4 × 10-9 to 2.2 × 10-6 cm3STP g-1 and shows a clear gradient with depth, suggesting addition of a 4Heterr flux entering the bottom of the eskers. Modeled 4Heterr fluxes range from 2.0 × 10-8 cm3STP cm-2 yr-1 at the Harricana moraine to 6.6 × 10-7 cm3STP cm-2 yr-1 in the southern section of the SMB esker. Calculated fluxes are highly variable and 5-165 times lower than the helium continental crustal flux, suggesting local helium sources, with helium being driven upward through preferential pathways such as local faults. Maximum U-Th/4He ages obtained for the groundwater in the fractured bedrock range from 1473 ± 300 a to 137 ± 28 ka, suggesting the occurrence of several generations of fossil meltwater trapped under the clay plain after the last two glaciations.

  12. Variation in Atmospheric Helium Isotopes

    NASA Astrophysics Data System (ADS)

    Mabry, J. C.; Marty, B.; Burnard, P.; Blard, P.

    2010-12-01

    Anthropogenic activity such as oil and gas exploitation releases crustal helium, which has excess 4He compared to atmospheric helium. This may give rise to both spatial and temporal variations in the atmospheric 3He/4He. Helium is present in trace quantities in the air (5 ppm) and has a very low ratio (3He/4Heair = 1.38 x 10-6), consequently high precision measurements of atmospheric He presents a significant analytical challenge. Recent work by Sano et al. [1] has endeavored to experimentally quantify these potential variations in the atmospheric 3He/4He by measuring the helium isotopes from air samples collected around the globe and from samples of ancient trapped atmosphere. Their results indicate an increase in the atmospheric 3He/4He from northern to southern latitudes of the order 2 - 4 ‰, which they attribute to greater use of fossil fuels in the northern hemisphere. However, since most of their data points overlap at the 2-3 ‰ (2σ) level, additional measurements (with increased precision if possible) are needed. We have constructed an automated extraction line dedicated to measuring He in samples of air which can rapidly switch between measuring aliquots of sample with standards. It additionally features an adjustable bellows on the sample aliquot volume that enables us to adjust the size of a sample aliquot to precisely match the standard, eliminating biases arising from nonlinear pressure effects in the mass spectrometer. The measurements are made using a Helix SFT multi-collector mass spectrometer. At present, repeat measurements of 3He/4He from our standard (purified air) have a reproducibility of 2‰ (2σ), while measurements of local (Nancy, France) air samples have a reproducibility of 3He/4He of 3‰ (2σ), which are at a similar level to the uncertainties reported by Sano. Modifications are underway to improve 3He measurements which are the principal source of error. We have collected atmospheric samples from around the globe over a wide

  13. Helium and Carbon isotopes of thermal springs hosted by deep faults in South China

    NASA Astrophysics Data System (ADS)

    Mao, X.; Wang, Y.; Yuan, J.

    2012-12-01

    Helium and carbon isotopes were important indicators to identify the origin of volatile dissolved in groundwater. Four thermal springs were sampled and discussed by helium and carbon isotopes for they were hosted by local deep faults and had significant connection to deep geothermal activity in Guangdong, China. 4He content of four thermal springs varied greatly from 3.72×10-8 to 199.54×10-8 cm3STP/mL, and 20Ne content varied greatly from 0.21×10-8 to 2.96×10-8 cm3STP/mL. While 3He/4He varied slightly from 0.36 to 0.57Ra (atmosphere 3He/4He ratio Ra=1.4×10-6). It indicated that the mixing of a lot of noble gases from other sources besides atmosphere not only changed the content of noble gases in groundwater, but also changed the isotopic compositions of noble gases, during the runoff process of groundwater. Because 22Ne was almost derived from atmosphere, an improved method of 4He/22Ne - 3He/4He was used to identify the origin of helium. 4% to 6% mantle He in thermal springs revealed that significant mantle He migrating in deep faults can bring a certain amount of energy along with thermal volatile and contribute to thermal spring formation. The δ13C value of four thermal springs was -3.79‰ to -2.17‰. Then dissolved inorganic carbon in thermal springs was speculated from rock metamorphism, it indicated geothermal activity. The four thermal springs were illustrated in the zone of crustal CO2 of rock inorganic chemistry, near to that of crust-mantle mixing CO2. It seemed that negligible or a small amount of volcanic mantle CO2 mixed with crustal CO2, and dissolved in thermal groundwater. So, δ13C revealed that dissolved inorganic carbon in thermal springs was from rock metamorphism occurred in certain deep crust as geothermal activity, which maybe the main energy source of thermal springs. Fig. 1. AIR (ASW)-MORB-CRUST mixing model of He and Ne isotopes. Fig. 2. CO2 origin identified by the relationship of δ13C and 3He/ 4He.

  14. Helium isotopes reveal a ubiquitous recycled component in the MORB mantle

    NASA Astrophysics Data System (ADS)

    Tucker, J.; Langmuir, C. H.; Mukhopadhyay, S.; Hamelin, C.; Fuentes, J.

    2015-12-01

    The region between the Kane and Hayes Fracture Zones in the northern Mid-Atlantic Ridge is an ideal laboratory to study mantle chemistry and crustal generation processes. This >1000 km length of ridge is devoid of known hotspots and major geochemical anomalies, but nonetheless exhibits systematic variations along strike in major and trace elements. To further understand the geochemistry of the depleted MORB reservoir distant from hot spots, we have carried out 57 new helium isotopic measurements along with measurements of Nd, Sr, Pb, and Hf isotopes. The 3He/4He ratios show a regional gradient from south to north that ranges from 8.3 to 10 Ra (where 1 Ra is the atmospheric ratio). The 3He/4He ratios correlate positively with 143Nd/144Nd, such that northern lavas have the highest 143Nd/144Nd and 3He/4He. These isotope variations correspond to a broad regional geochemical gradient from more enriched compositions in the south to more depleted compositions in the north. Nd and Pb isotopes at the northern end of this region extend to compositions significantly more depleted than average MORB, raising the possibility that the high 3He/4He ratios reflect the depleted mantle end member, which may have 3He/4He higher than 10 Ra. Other studies have also identified a depleted end member of at least ~9-10 Ra elsewhere in the Atlantic (Tucker et al., 2012), Pacific (Hamelin et al., 2011), and Indian (Graham et al. 2014) ridge systems. This suggests that globally, normal MORBs, which are often quoted as 8±1 Ra, are more radiogenic (lower 3He/4He) than the depleted end member. Because radiogenic helium comes from recycled (degassed) material, we conclude that the average MORB mantle must contain a substantial amount of the recycled material, contributing 10s of percent of the helium even in MORBs that are not particularly enriched. Furthermore, observations of helium isotopes less radiogenic than the nominal MORB range (e.g., 10-11 Ra) need not always reflect a primitive

  15. Helium isotopes of the Siberian sub-continental lithospheric mantle: Insights from eclogite xenoliths

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Hilton, D. R.; Day, J. M.; Pernet-Fisher, J.; Howarth, G. H.; Taylor, L. A.

    2014-12-01

    Helium isotopes (3He/4He) have been extensively used to define distinct segments of Earth's mantle and characterize its chemical structure. Specifically, they have been used to illustrate the long-term isolation and preservation of high-3He/4He (≥50 RA; [1]) plume-derived materials from the well-mixed and more-extensively degassed depleted MORB mantle (DMM) (8 RA; [2]). However, the He-isotope signature of the sub-continental lithospheric mantle (SCLM) remains relatively poorly characterized (6.1 RA; [3]). The Siberian craton hosts >1000 kimberlite intrusions, which carry mantle-derived xenoliths - of varying compositions (i.e., peridotites, dunites, and eclogites) - to the Earth's surface, making it an ideal setting for investigating the chemical evolution of the SCLM. Here, we report new He-isotope and concentration data for a suite of eclogitic xenoliths (n=10) from the Udachnaya pipe, Siberia. He-isotopes and [He] contents were determined by crushing garnet and pyroxene mineral separates from 2.7-3.1 Ga Siberian eclogites. 3He/4He values ranged from 0.11 to 1.0 RA, displaying predominantly radiogenic (i.e., low 3He/4He) He-isotope values. In contrast, Siberian flood basalt values extend up to ~13 RA [4]. Helium concentrations span ~4 orders of magnitude from 60 to 569,000 [4He]C ncm3STP/g. The radiogenic nature of Udachnaya eclogites indicate that they have been largely isolated from basaltic metasomatic fluxes over geological time due to position within the lithosphere and/or lithospheric age. Further, low 3He/4He values may reflect the addition of high U-Th material into the lithosphere by accretion of ancient island-arc terrains. These new data add to the growing He-isotope database [5,6] for the Siberian SCLM, and reveal the heterogeneous nature of this region with respect to He-isotopes, as well as the potential importance of crustal recycling and metasomatic processes. [1] Stuart et al., 2003. Nature. [2] Graham, 2002. Reviews in Mineralogy and

  16. Volatile fluxes through the Big Bend section of the San Andreas Fault, California: helium and carbon-dioxide systematics

    USGS Publications Warehouse

    Kulongoski, Justin T.; Hilton, David R.; Barry, Peter H.; Esser, Bradley K.; Hillegonds, Darren; Belitz, Kenneth

    2013-01-01

    To investigate the source of volatiles and their relationship to the San Andreas Fault System (SAFS), 18 groundwater samples were collected from wells near the Big Bend section of the SAFS in southern California and analyzed for helium and carbon abundance and isotopes. Concentrations of 4He, corrected for air-bubble entrainment, vary from 4.15 to 62.7 (× 10− 8) cm3 STP g− 1 H2O. 3He/4He ratios vary from 0.09 to 3.52 RA (where RA = air 3He/4He), consistent with up to 44% mantle helium in samples. A subset of 10 samples was analyzed for the major volatile phase (CO2) — the hypothesized carrier phase of the helium in the mantle–crust system: CO2/3He ratios vary from 0.614 to 142 (× 1011), and δ13C (CO2) values vary from − 21.5 to − 11.9‰ (vs. PDB). 3He/4He ratios and CO2 concentrations are highest in the wells located in the Mil Potrero and Cuddy valleys adjacent to the SAFS. The elevated 3He/4He ratios are interpreted to be a consequence of a mantle volatile flux though the SAFS diluted by radiogenic He produced in the crust. Samples with the highest 3He/4He ratios also had the lowest CO2/3He ratios. The combined helium isotope, He–CO2 elemental relationships, and δ13C (CO2) values of the groundwater volatiles reveal a mixture of mantle and deep crustal (metamorphic) fluid origins. The flux of fluids into the seismogenic zone at high hydrostatic pressure may cause fault rupture, and transfer volatiles into the shallow crust. We calculate an upward fluid flow rate of 147 mm a− 1 along the SAFS, up to 37 times higher than previous estimates (Kennedy et al., 1997). However, using newly identified characteristics of the SAFS, we calculate a total flux of 3He along the SAFS of 7.4 × 103 cm3 STP a− 1 (0.33 mol 3He a− 1), and a CO2 flux of 1.5 × 1013 cm3STP a− 1 (6.6 × 108 mol a− 1), ~ 1% of previous estimates. Lower fluxes along the Big Bend section of the SAFS suggest that the flux of mantle volatiles alone is insufficient to cause the

  17. Depth-dependent Concentrations of Cosmogenic 10Be, 26Al, 36Cl, HEc, NEc, and ARc in the Old Woman Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Lavielle, B.; Nishiizumi, K.; Marti, K.; Jeannot, J.-P.; Caffee, M. W.; Finkel, R. C.

    1995-09-01

    We report measurements of 1OBe7 26AI, 36CI, and of light noble gases in 6 samples of the type IIB Old Woman iron meteorite. The aim of this work is to study the depth dependence of the production rates of cosmogenic nuclides in iron meteorites. Old Woman is a large single mass of 2753 kg. Five samples have been taken from a slice of about 100 cm x 50 cm. One other sample was located roughly 40 cm above the center of the slice in a perpendicular direction. The distances between any two samples vary from 36.5 cm to 57.5 cm. Studies of cosmogenic nuclides in samples of known locations are very useful for the validation of models describing the production of cosmogenic nuclides in meteorites. Cosmogenic radionuclides were measured by accelerator mass spectrometry at Lawrence Livermore National Laboratory. Partial results have been reported earlier [1]. Concentrations of 4He, 21Ne and 38Ar in aliquots of the samples were determined by conventional mass spectrometry using an isotopic dilution method. The ratio 3He/4He appears to be almost constant with a value of 0.12 - ().13. This is about half the value generally observed in iron meteorites. Similar low ratios have been previously observed in some irons and in chondritic metal and reflect diffusion losses of 3H 12,31. The ratios 4He/38Ar, 4He/21Ne and 36Ar/38Ar are similar to those observed in iron meteorites indicating no significant losses of 4He. The measured ratio S = 4He/21Ne which represents one of the best indicators of shielding depth in iron meteorites, varies from 310 to 375 in samples from the slice. By using this as a shielding parameter, profiles were obtained for the different nuclides investigated in this work. Systematic decreases from the surface to the center of the meteorite are observed and the center of the meteoroid can be determined. As expected from nuclear systematics, the ratio 36Cl/36Ar is almost constant. The ratio 36Cl/10Be is relatively constant with a mean value of 4.7 indicating that the

  18. Flow of mantle fluids through the ductile lower crust: Heliumisotope trends

    SciTech Connect

    Kennedy, B. Mack; van Soest, Matthijs C.

    2007-10-07

    Heat and mass are injected into the shallow crust when mantle fluids are able to flow through the ductile lower crust. Minimum 3He/4He ratios in surface fluids from the northern Basin and Range province, western North America increase systematically from low, crustal values in the east to high, mantle values in the west, a regional trend that correlates with the rates of active crustal deformation. The highest ratios occur where the extension and shear strain rates are greatest. The correspondence of helium isotope ratios and active trans-tensional deformation indicates a deformation enhanced permeability and that mantle fluids can penetrate the ductile lithosphere in regions even where there is no significant magmatism. Superimposed on the regional trend are local, high-{sup 3}He/{sup 4}He anomalies signifying hidden magmatic activity and/or deep fluid production with locally enhanced permeability, identifying zones with high resource potential, particularly for geothermal energy development.

  19. He, Ne, Ar, and C isotope systematics of geothermal emanations in the Lesser Antilles Islands Arc

    SciTech Connect

    Pedroni, A.; Hammerschmidt, K.; Friedrichsen, H.

    1999-02-01

    The authors present He, Ne, Ar, and C isotope analyses of hydrothermal brines and gases from fumaroles, hot springs, mofettes and hydrothermal exploration drillings on the major islands of the Lesser Antilles Arc. The origin of hydrothermal brines, which have been analyzed also for O and H isotopes, is essentially meteoric-hydrothermal. Air-corrected isotope compositions of helium (2.2 Rc/Ra < {sup 3}He/{sup 4}He < 8.6 Rc/Ra) and carbon ({minus}20 < {delta}{sup 13}C{sub PDB} < +0.5) are variable and require a variety of crustal and magmatic sources. The diversity of {delta}{sup 13}C{sub PDB} and {sup 3}He/CO{sub 2} ratios within individual volcanic centers suggests that crustal sources (e.g., limestone) contaminate magmatic CO{sub 2} en route from high-level magma reservoirs (depth < 15 km) to the surface. A similar contamination may be found for magmatic helium on distal springs. The {sup 3}He/{sup 4}He signature of summit fumaroles, thought to reflect the {sup 3}He/{sup 4}He signature of high-level magmas, shows a remarkable systematic variation along the arc. In addition, there is a correlation throughout the arc between published Sr, Pb, and Nd isotope signatures of lavas and the {sup 3}He/{sup 4}He signatures of summit fumaroles. On the northern islands (Nevis, Montserrat, Guadeloupe, and Dominica) summit fumaroles have the N-MORB signature ({sup 3}He/{sup 4}He = 8 {+-} 1 R/Ra), and the isotope signature of lavas is not dissimilar from comparable intra-oceanic arc tholeiites elsewhere. Variable enrichments in radiogenic Sr and Pb have been reported for lavas of individual volcanic centers of the Southern Islands (Martinique, St Lucia, and Grenada), and summit fumaroles on these centers match these variations by variable radiogenic He-enrichments, i.e., lower {sup 3}He/{sup 4}He ratios. This correlation suggests that radiogenic Sr and Pb enrichments of lavas and low {sup 3}He/{sup 4}He signatures on summit fumaroles have a common origin, i.e., a terrigenous

  20. Theory of the Lamb shift in muonic helium ions

    SciTech Connect

    Krutov, A. A.; Martynenko, A. P. Martynenko, G. A.; Faustov, R. N.

    2015-01-15

    The Lamb shift (2P{sub 1/2}-2S{sub 1/2}) in muonic helium ions (μ{sub 2}{sup 3}){sup +}, (μ{sup 2/4}He){sup +} is calculated taking into account the contributions of the order of α{sup 3}, α{sup 4}, α{sup 5}, and α{sup 6}. Special attention is paid to corrections for the polarization of the vacuum, as well as the structure and recoil of the nucleus. Numerical values 1259.8583 meV ((μ{sub 2}{sup 3}He){sup +}) and 1379.1107 meV ((μ{sub 2}{sup 4}He){sup +}) obtained for the shifts can be considered reliable estimates when compared to the experimental data of the CREMA collaboration.