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Sample records for 4he linejno polyarizovannymi

  1. Experiments with solid 4He

    NASA Astrophysics Data System (ADS)

    Hallock, R. B.

    2010-08-01

    The possibility of supersolid behavior in 4He was predicted many years ago, but negative experiments in the 1970’s removed motivation for further experimental efforts to explore the possibility until the work of Goodkind’s group renewed attention. Kim and Chan found unambiguous evidence for a period shift in a torsional oscillator filled with solid 4He and this observation and its interpretation have created substantial interest in the study of solid 4He. Here, recent work with an experimental design that allows for superfluid 4He to be in direct contact with solid 4He off the melting curve will be discussed and evidence for the flow of helium atoms through a cell filled with solid 4He, caused by an applied chemical potential difference will be briefly reviewed.

  2. Aspects of 4He II

    NASA Astrophysics Data System (ADS)

    Cummings, F. W.

    1981-10-01

    Some recent assertions concerning Fröhlich's form for the second-order reduce density matrix for 4He II are shown to be incorrect, based on work by McMillan and Whitlock et al. An ansatz to replace the Beliaev ansatz is advanced, which leads directly to Fröhlich's form.

  3. Coulomb sum rule for {sup 4}He

    SciTech Connect

    J. Carlson; J. Jourdan; R. Schiavilla; I. Sick

    2002-10-01

    We determine the Coulomb sum for {sup 4}He using world data on {sup 4}He(e, e') and compare the results to calculations based on realistic interactions and including two-body components in the nuclear charge operator. We find good agreement between theory and experiment using free-nucleon form factors. The apparent reduction of the in-medium G{sub ep} implied by IA-interpretation of the L/T-ratios measured in {sup 4}He(e,e'p) and {sup 4}He([vec]e, e'p) is not confirmed.

  4. Zircon 4He/3He thermochronometry

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  5. Exploration of Vacancies in Solid 4^He

    NASA Astrophysics Data System (ADS)

    Clark, Bryan; Ceperley, David

    2006-03-01

    Experiments by Kim and Chan [1] have renewed interest in the understanding of supersolids and whether mechanisms exist in solid ^4He to allow for supersolid-like effects. Ground state vacancies would lead to bose condensation and superfluidity. Using Path Integral Monte Carlo we examine vacancy formation energies, vacancy-vacancy interactions and the effect of vacancies on supersolid behavior in solid ^4He. [1] E. Kim and M. H. Chan, Science 305, 1941 (2004).

  6. {sup 4}He microscopic optical model potential

    SciTech Connect

    Guo Hairui; Liang Haiying; Han Yinlu; Shen Qingbiao; Xu Yongli

    2011-06-15

    The {sup 4}He microscopic optical model potential is obtained by Green's function method through nuclear matter approximation and local density approximation based on the effective Skyrme interaction. The microscopic optical model potential is analyzed and utilized to calculate the reaction cross sections and elastic scattering angular distributions for the target nuclei in the mass range 12{<=}A{<=}209 with incident {sup 4}He energy up to 400 MeV. The theoretical results are compared with the experimental data.

  7. 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.

  8. The Annealing Process in Solid 4He

    NASA Astrophysics Data System (ADS)

    Rittner, Ann Sophie C.; Reppy, John D.

    2007-09-01

    We have used a torsional oscillator with square cross section and a resonance frequency of 185 Hz to confirm the nonclassical rotational inertia (NCRI) discovered by Kim and Chan (Nature 427:225, 2004; Science 305:1941, 2004). We have also found a strong correlation between the NCRI signal and a high dissipation Q -1 of 4×10-6 of the oscillation above the transition temperature. Here, we present preliminary results of the annealing process in 4He at a pressure of 26 bar. When holding the temperature constant above 1 K we have observed a immediate rise in the period and a slow decay of the dissipation. The equilibrium value of Q -1 decreases with increasing temperature.

  9. 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.

  10. 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.

  11. Positive ion induced solidification of 4He.

    PubMed

    Moroshkin, P; Lebedev, V; Weis, A

    2009-03-20

    We have observed bulk solidification of 4He induced by nucleation on positive alkali ions in pressurized superfluid helium. The ions are extracted into the liquid from alkali-doped solid He by a static electric field. The experiments prove the existence of charged particles in a solid structure composed of doped He that was recently shown to coexist with superfluid helium below the He solidification pressure. This supports our earlier suggestion that the Coulomb interaction of positive ions surrounded by a solid He shell (snowballs) and electrons trapped in spherical cavities (electron bubbles), together with surface tension, is responsible for the stability of that structure against melting. We have determined the density of charges in the sample by two independent methods. PMID:19392211

  12. Astrophysical S factors of radiative {sup 3}He{sup 4}He, {sup 3}H{sup 4}He, and {sup 2}H{sup 4}He capture

    SciTech Connect

    Dubovichenko, S. B.

    2010-09-15

    The possibility of describing the astrophysical S factors for radiative {sup 3}He{sup 4}He capture at energies of up to 15 keV and radiative {sup 3}H{sup 4}He and {sup 2}H{sup 4}He capture at energies of up 5 keV is considered on the basis of the potential cluster model involving forbidden states.

  13. 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.

  14. Microscopic characterization of overpressurized superfluid 4He

    NASA Astrophysics Data System (ADS)

    Rossi, M.; Vitali, E.; Reatto, L.; Galli, D. E.

    2012-01-01

    We have studied static and dynamical properties of superfluid 4He at T=0 K in the pressure range from -6 up to 87 atm well above freezing into the metastable region. Zero temperature properties have been obtained with the exact shadow path integral ground state (SPIGS) method. Information about dynamic structure factors at different pressures have been obtained from imaginary time correlation functions via the genetic inversion via falsification of theories (GIFT) method. In the full pressure range sharp roton excitations are always present in the spectral functions. The roton energy decreases at higher pressures in good agreement with experimental data also in the metastable region. The roton energies have essentially a linear trend with pressure, going from about 7.4 K near freezing to about 4.3 K at about 87 atm. The pressure at which the linear trend would extrapolate to a zero roton energy turns out to be about 170 atm. At T=0 K, no sign of metastable glass phase has been found; the disordered systems studied at pressures above about 87 atm readily start homogeneous nucleation processes. Our results in the metastable phase for the condensate fractions and roton gaps differ remarkably from previous ones obtained via a diffusion Monte Carlo study.

  15. Search for dislocation free 4He crystals

    NASA Astrophysics Data System (ADS)

    Souris, Fabien; Fefferman, Andrew; Haziot, Ariel; Beamish, John; Balibar, Sebastien

    2014-03-01

    The elastic anomaly of 4He crystals is known to be a consequence of the motion of their dislocations. We have built an acoustic cell in order to grow and study crystals with the smallest possible density of dislocations. It has a polished inner surface to avoid pinning sites for the liquid-solid interface. Piezoelectric transducers are placed outside the cell volume, in order to drive and detect acoustical resonances through built-in copper membranes. We expect dislocation free crystals to behave rather differently from the usual ones (1,2). For example, they should not show any anomalous softening. Preliminary results show that crystals grown in this particular cell have longer dislocation lengths than in those studied in previous experiments (1,2). Centimeter long dislocations should resonate below 20 kHz. 1- A. Haziot et al., Phys. Rev. Lett. 110, 035301 (2013), Phys. Rev. B 87, 060509(R) (2013), and Phys. Rev. B 88, 014106 (2013). 2- A. D. Fefferman et al., submitted to Phys. Rev. B, Nov. 2013. ERC Grant AdG247258 SUPERSOLID and NSERC Canada.

  16. Measurements of diffuse and specular scattering of sup 4 He atoms from sup 4 He films

    SciTech Connect

    Mukherjee, S.

    1989-01-01

    We have observed scattering of {sup 4}He atomic beams from films of {sup 4}He on glass and mica substrates. The specular reflection coefficient, or reflectivity, R(k,{theta}) was measured as a function of the angle of incidence {theta} and the wavevector k of the incident atoms, and the thickness of the film. The film thickness d varied from 45 {angstrom} to macroscopic values. In contrast to previous experiments on scattering from 10 cm deep liquid, we observed not only the expected specular reflection, but also isotropic diffuse scattering. To explain the diffuse signal, we assume that most of the incident atoms are converted into phonons, rotons and ripplons at the surface of the film. The phonons and rotons are scattered at the substrate, and subsequently evaporate an isotropic distribution of atoms.

  17. 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.

  18. 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.

  19. Solid 4He probed by both torsional oscillator and ultrasound

    NASA Astrophysics Data System (ADS)

    Kojima, Harry; Iwasa, Izumi; Goodkind, John

    2013-03-01

    The interpretation of observed anomalous increases in the frequencies of torsional oscillators (TO) containing solid 4He confined in Vycor nanopores as evidence for emergence of a supersolid phase has been met recently by conflicting experiments. Yet questions remain on the origin of the observed TO anomalies in bulk solid 4He samples. To search for the origin, we are carrying out simultaneous measurements of 10 MHz longitudinal ultrasound and TOs (250 ~ 1100 Hz) on identical solid 4He samples. Temperature dependence of velocity and attenuation of ultrasound and that of amplitude and frequency of TO are measured. At the temperatures, where TO anomalies occur, anomalies in sound velocity and attenuation also appear. When solid 4He is doped with 20 ppm 3He, the tempeature of TO anomaly tracks that of ultrasound. Interpretation of these observations in terms of the motion of dislocation lines will be presented. Research supported by NSF.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. A Summary of Mass Flux Measurements in Solid 4He

    NASA Astrophysics Data System (ADS)

    Hallock, R. B.; Ray, M. W.; Vekhov, Y.

    2012-11-01

    Here we provide a summary and brief review of some of the work done with solid 4He at the University of Massachusetts Amherst below a sample pressure of 28 bar. The motivation for the work has been to attempt to pass 4He atoms through solid 4He without directly applying mechanical pressure to the solid itself. The specific technique chosen is limited to pressures near the melting curve and was initially designed to provide a yes/no answer to the question of whether or not it might be possible to observe such a mass flux. The thermo-mechanical effect and direct mass injection have been separately used to create chemical potential differences between two reservoirs of superfluid 4He connected to each other through superfluid-filled Vycor rods in series with solid 4He, which is in the hcp region of the phase diagram. The thermo-mechanical effect is a more versatile approach. And, in a particular symmetric application it is designed to provide a mass flux with little or no net increase in the density of the solid. Our observations, off but near the melting curve, have included: (1) the presence of an increasing DC flux of atoms through the solid-filled cell with decreasing temperature below ≈650 mK and no flux above this temperature; (2) the presence of a flux minimum and flux instability in the vicinity of 75-80 mK, with a flux increase at lower temperatures; (3) the temperature dependence of the flux above 100 mK and the dependence of the flux on the net driving chemical potential difference provide interesting insights on the possible mechanism that leads to the flux above 100 mK. The most recent data suggest that whatever is responsible for the flux in solid 4He, at least for T>100 mK, may be an example of a Bosonic Luttinger liquid.

  4. Transverse beam asymmetries from $^4$He and hydrogen targets

    SciTech Connect

    Lisa Kaufman

    2007-07-01

    The HAPPEX Collaboration at Jefferson Lab has measured the transverse beam spin asymmetries ($A_T$) for elastic electron scattering from proton and $^4$He targets. The experiment was conducted using a vertically polarized electron beam of energy ~3 GeV at $Q^2$ ~0.1 GeV$^2$ and a scattering angle $\\theta_{lab}$ ~6$^{\\circ}$. The preliminary results are reported here. The $^4$He measurement is non-neglible; therefore, it will be necessary to make measurements of $A_T$ for future parity-violating experiments using nuclear targets

  5. Transverse Ultrasound Measurements in 4He Single Crystals

    NASA Astrophysics Data System (ADS)

    Syshchenko, O.; Beamish, J.

    2008-02-01

    Recently, Kim and Chan (Science 305:1941, 2004; Phys. Rev. Lett. 97:115302, 2006) have reported an anomalous decoupling transition of solid 4He in a torsional oscillator measurement, and interpret their results as evidence for non-classical rotational inertia and a possible supersolid phase of 4He. The detailed nature and properties of such a “supersolid” state in 4He are still far from being clear, although there are clues from experiments involving 3He impurities, different sample cell geometries, annealing effects and grain boundary flow. Defects produced during crystal growth or deformation (e.g. dislocations) may affect supersolidity, or even produce it, and they are expected to have significant impact on the elastic properties of the solid. The supersolid fraction could also decouple from the lattice and produce a decrease in the transverse sound speed. We have begun the experiments in this laboratory to study such effects, measuring the velocity and attenuation of transverse ultrasound at 10 MHz in 4He single crystals grown at constant pressure.

  6. 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 .

  7. Small Multielectron Bubbles in Bulk Superfluid 4He

    SciTech Connect

    Lehtovaara, Lauri; Eloranta, Jussi

    2006-09-07

    A computational method for describing multielectron bubbles in bulk superfluid helium (4He) is described. The developed method can be used to study their stability and spectroscopic properties in both singlet and triplet manifolds. Our initial results indicate meta-stability of the spherical two-electron bubble in its singlet ground state.

  8. Study of states in 14C via the 10Be(4He,4He)10Be reaction

    NASA Astrophysics Data System (ADS)

    Malcolm, J. D.; Freer, M.; Ashwood, N. I.; Curtis, N.; Munoz-Britton, T.; Wheldon, C.; Ziman, V. A.; Catford, W. N.; Brown, S.; Wilson, G.; Soic, N.; Bardayan, D.; Pain, S. D.; Achouri, N. L.; Chipps, K.; Crzywacz-Jones, K.

    2012-09-01

    A study of the 10Be(4He,4He)10Be reaction has been performed at 10Be beam energies of 25.0, 27.0, 29.0, 32.0, 34.0, 38.0, 40.0, 42.0, 44.0 and 46.0 MeV. The measurements were to explore possible molecular rotational bands in 14C. Three states at excitation energies of Ex = 18.8, 19.76 and 20.66 MeV have been measured and their spins have been determined to be 5-, 5- and 6+, respectively.

  9. Generalized Rotational Susceptibility Studies of Solid 4He

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    Using a novel SQUID-based torsional oscillator (TO) technique to achieve increased sensitivity and dynamic range, we studied TO's containing solid 4He. Below ˜250 mK, the TO resonance frequency f increases and its dissipation D passes through a maximum as first reported by Kim and Chan. To achieve unbiased analysis of such 4He rotational dynamics, we implemented a new approach based upon the generalized rotational susceptibility χ{4He}^{ - 1}(ω,T). Upon cooling, we found that equilibration times within f( T) and D( T) exhibit a complex synchronized ultraslow evolution toward equilibrium indicative of glassy freezing of crystal disorder conformations which strongly influence the rotational dynamics. We explored a more specific χ{4He}^{ -1}(ω,tau(T)) with τ( T) representing a relaxation rate for inertially active microscopic excitations. In such models, the characteristic temperature T ∗ at which df/ dT and D pass simultaneously through a maximum occurs when the TO angular frequency ω and the relaxation rate are matched: ωτ( T ∗)=1. Then, by introducing the free inertial decay (FID) technique to solid 4He TO studies, we carried out a comprehensive map of f( T, V) and D( T, V) where V is the maximum TO rim velocity. These data indicated that the same microscopic excitations controlling the TO motions are generated independently by thermal and mechanical stimulation of the crystal. Moreover, a measure for their relaxation times τ( T, V) diverges smoothly everywhere without exhibiting a critical temperature or velocity, as expected in ωτ=1 models. Finally, following the observations of Day and Beamish, we showed that the combined temperature-velocity dependence of the TO response is indistinguishable from the combined temperature-strain dependence of the 4He shear modulus. Together, these observations imply that ultra-slow equilibration of crystal disorder conformations controls the rotational dynamics and, for any given disorder conformation, the

  10. 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.

  11. 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.

  12. 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.

  13. The Nature of the Glassy Phase in 4He Crystals

    NASA Astrophysics Data System (ADS)

    Antsygina, T. N.; Poltavskaya, M. I.; Chishko, K. A.

    2015-08-01

    A model of a close-packed polytype with a random stacking fault structure is used to interpret the anomalies of the thermodynamic properties of the disordered (glassy) phase in solid HCP 4He in the so-called supersolid state. The temperature dependence of the phonon pressure is calculated theoretically, and compared to experimental data. A quantitative agreement between the theory and the experiment is achieved.

  14. 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.

  15. 4He crystals in superfluid under zero gravity.

    PubMed

    Takahashi, Takuya; Nomura, Ryuji; Okuda, Yuichi

    2012-03-01

    The response of 4He crystals to the rapid reduction of gravity down to practically zero in a superfluid was investigated visually, utilizing the parabolic flight of a jet plane. At a high temperature of 1.6 K, the shape of 4He crystals in the bcc phase did not change with a reduction of gravity during a parabolic period of 20 s, due to the low crystallization rate. At lower temperatures, such as 0.63 K, where the crystallization rate is sufficiently high, the shape of 4He crystals in the hcp phase changed significantly, relaxing to a quasiequilibrium shape under zero gravity, where the c facet became enlarged and the a facet emerged on the surface. The crystal did not detach from the sample cell wall at any time because the adhesive force manifested as partial wetting to the wall was sufficiently strong. Some crystals removed from the wall by an acoustic wave pulse were found to float and drift in the superfluid for approximately 4.2 s under zero gravity, although most of them were quickly reattached to the wall. PMID:22587030

  16. Dry dilution refrigerator with 4He-1 K-loop

    NASA Astrophysics Data System (ADS)

    Uhlig, Kurt

    2015-03-01

    In this article we summarize experimental work on cryogen-free 3He/4He dilution refrigerators which, in addition to the dilution refrigeration circuit, are equipped with a 4He-1 K-stage. This type of DR becomes worth considering when high cooling capacities are needed at T ∼ 1 K to cool cold amplifiers and heat sink cables. In our application, the motivation for the construction of this type of cryostat was to do experiments on superconducting quantum circuits for quantum information technology and quantum simulations. In other work, DRs with 1 K-stage were proposed for astro-physical cryostats. For neutron scattering research, a top-loading cryogen-free DR with 1 K-stage was built which was equipped with a standard commercial dilution refrigeration insert. Cooling powers of up to 100 mW have been reached with our 1 K-stage, but higher refrigeration powers were achieved with more powerful pulse tube cryocoolers and higher 4He circulation rates in the 1 K-loop. Several different versions of a 1 K-loop have been tested in combination with a dilution refrigeration circuit. The lowest temperature of our DR was 4.3 mK.

  17. 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

  18. 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.

  19. 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.

  20. Vacancy distribution in a rotating solid 4He

    NASA Astrophysics Data System (ADS)

    Pushkarov, D. I.

    2012-03-01

    Vacancy distribution is considered in a rotating solid 4He immersed in a superfluid helium-II. Vacancies are considered as a quasiparticle gas of vacancions with a gap dispersion law. It is shown that the radial distribution depends on Poisson's ratio and practically not on Young's modulus. The treatment is based on a nonlinear theory unifying the elasticity theory equations and a Boltzmann-type transport equation valid for arbitrary angular velocities. The situation simulates, in a sense, the Kim and Chan rotational experiments where nonclassical inertia was observed. The model cannot be applied to solid 3He. We do not presuppose in this work any supersolid fraction.

  1. 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.

  2. 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.

  3. 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

  4. Deeply Virtual Compton Scattering off ^4He nucleus

    NASA Astrophysics Data System (ADS)

    El Alaoui, Ahmed

    2010-02-01

    The recently developed formalism of generalized parton distributions (GPDs) provides a theoretical tool to reveal the internal structure of the nucleon. These objects can be obtained via Deeply Virtual Compton Scattering (DVCS) processes. They contain informations on the transverse spatial position and the longitudinal momentum of quarks inside the nucleon and they also give access to the contribution of the quark orbital angular momentum to the nucleon. In contrast to many DVCS experiments using a proton target, only few experiments are devoted to study GPDs in a nuclear target which is important because it allows to address medium modification of bound nucleon GPDs compared to free nucleon GPDs. One of the goals of the new EG6 experiment at Thomas Jefferson Laboratory is to extract the real and imaginary parts of the ^4He Compton form factor (HA(xB,t)) from measurement of beam spin asymmetries by scattering a polarized 6 GeV electron beam off a ^4He pressurized gaz target. Details on the experiment will be presented here. )

  5. 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

  6. Superfluidity, BEC, and dimensions of liquid 4He in nanopores

    NASA Astrophysics Data System (ADS)

    Markić, L. Vranješ; Glyde, H. R.

    2015-08-01

    We present path integral Monte Carlo (PIMC) calculations of the superfluid fraction, ρS/ρ , and the one-body density matrix (OBDM) [Bose-Einstein condensation (BEC)] of liquid 4He confined in nanopores. Liquid 4He in nanopores represents a dense Bose liquid at reduced dimension and in disorder. The goal is to determine the effective dimensions of the liquid in the pores. It is to test whether observed properties, such as a very low onset temperature for superflow, Tc, can be predicted by a standard, static PIMC ρS/ρ . We simulate a cylinder of liquid of diameter dL surrounded by 5 Å of inert solid 4He in a nanopore of diameter d ; d =dL+10 Å . We find a PIMC ρS(T ) /ρ and OBDM that scales as a 1D fluid Luttinger liquid at extremely small liquid pore diameters only, dL=6 Å . At this dL, the liquid fills the pore in a 1D line at the center of the pore and there is no PIMC superflow. In the range 8 ≤dL≤22 Å the PIMC ρS(T ) /ρ scales as a 2D liquid. In this dL range the liquid fills the pores in 2D-like cylindrical layers. The crossover from no superflow at d =16 Å to superflow at d ≥18 Å agrees with experiment. There is a crossover to 3D scaling at larger dL≃22 Å . In the range 8 ≤dL≤22 Å , the Tc predicted using the Kosterlitz-Thouless 2D scaling criterion of the OBDM agrees well with that obtained from ρS(T ) /ρ . These results suggest that the superflow observed in small pore media is standard static superflow with the low Tc arising from its 2D character. An operational onset temperature, TBEC, for BEC can be defined as the temperature at which there is a crossover from exponential to algebraic decay in the OBDM. This definition leads to a TBEC≥Tc as observed in larger pore media.

  7. Non-relativistic approximations to the pion production operator in 4He(p, n π+) 4He

    NASA Astrophysics Data System (ADS)

    Greben, J. M.; Woloshyn, R. M.

    1980-01-01

    Various non-relativistic pion production operators are applied in the study of the 4He(p, nπ +) 4He process. We compare their predictions with fully covariant calculations of the external emission graphs both for pseudovector and pseudoscalar coupling. It is found that the non-relativistic pion production operators cannot reproduce the relativistic results quantitatively, in particular for the pseudoscalar case. The simple static pion production operator gives agreement with the relativistic pseudovector results to within a factor three or four. Adding recoil terms to this static operator has a significant effect on the cross section but does not improve the agreement with the relativistic results. The implications of PCAC and the soft-pion theorem for the relativistic calculation are studied. The uncertainty in the cross section in the soft-pion approach is found to be considerably smaller than the difference between pseudovector and pseudoscalar results or between the relativistic pseudovector result and its non-relativistic approximations.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Metastable Helium Molecules as Tracers in Superfluid {sup 4}He

    SciTech Connect

    Guo, W.; Wright, J. D.; Cahn, S. B.; Nikkel, J. A.; McKinsey, D. N.

    2009-06-12

    Metastable helium molecules generated in a discharge near a sharp tungsten tip immersed in superfluid {sup 4}He are imaged using a laser-induced-fluorescence technique. By pulsing the tip, a small cloud of He{sub 2}* molecules is produced. We can determine the normal-fluid velocity in a heat-induced counterflow by tracing the position of a single molecule cloud. As we run the tip in continuous field-emission mode, a normal-fluid jet from the tip is generated and molecules are entrained in the jet. A focused 910 nm pump laser pulse is used to drive a small group of molecules to the first excited vibrational level of the triplet ground state. Subsequent imaging of the tagged molecules with an expanded 925 nm probe laser pulse allows us to measure the flow velocity of the jet. The techniques we developed provide new tools in quantitatively studying the normal fluid flow in superfluid helium.

  15. Metastable helium molecules as tracers in superfluid 4He.

    PubMed

    Guo, W; Wright, J D; Cahn, S B; Nikkel, J A; McKinsey, D N

    2009-06-12

    Metastable helium molecules generated in a discharge near a sharp tungsten tip immersed in superfluid 4He are imaged using a laser-induced-fluorescence technique. By pulsing the tip, a small cloud of He(2*) molecules is produced. We can determine the normal-fluid velocity in a heat-induced counterflow by tracing the position of a single molecule cloud. As we run the tip in continuous field-emission mode, a normal-fluid jet from the tip is generated and molecules are entrained in the jet. A focused 910 nm pump laser pulse is used to drive a small group of molecules to the first excited vibrational level of the triplet ground state. Subsequent imaging of the tagged molecules with an expanded 925 nm probe laser pulse allows us to measure the flow velocity of the jet. The techniques we developed provide new tools in quantitatively studying the normal fluid flow in superfluid helium. PMID:19658945

  16. 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.

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

    PubMed

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

    2005-08-01

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

  18. Excitations of Superfluid ^4He at Wavevectors Beyond the Roton

    NASA Astrophysics Data System (ADS)

    Glyde, Henry; Sakhel, Asaad

    2002-03-01

    We present a Quantum Field Theoretical Model that reproduces the basic features of the temperature dependence of the dynamic structure factor S(Q,ω) of ^4He as observed in the inelastic-neutron scattering data taken at ISIS( J. V. Pierce, R. T. Azuah, B. F, A. R. Sakhel, H. R. Glyde, W. G. Stirling, J. Phys: Cond. Matter, 13(2001) 4421., UK. A range of the wavevectors Q beyond the roton (Q > 2.0 Åis considered. The model is able to reproduce the decrease in the intensity of the single-particle excitation peak with increase of T in the range 0.6 <= T <= 2.1 K. Also, it reproduces the second peak at higher energy representing the single excitation intensity lying in the two excitation band. The model is based on the formulation of S(Q,ω) of Gavoret and Nozières( J. Gavoret and P. Nozières, Ann. Phys., 28, 349-399 (1964). In this formulation, the dynamic susceptibility is separated into a singular part involving the condensate and a regular part involving states above the condensate \\chi = \\chiS + \\chi_R. Here \\chiS = n n_0(T) Λ G Λ, Λ is a vertex, G the renormalized single particle Green's function, n the density of ^4He at SVP and n_0(T) the condensate fraction as a function of T. \\chi_R(Q,ω) involves both a single particle-hole and a multiparticle component. All vertices and interactions are assumed T-independent, and only n0 changes with T. Also, the roton width is accounted for by a momentum (k) and temperature dependent width of the Landau-Khalatnikov form (H. R. Glyde, Excitations in Liquid and Solid helium), Oxford, Clarendron Press, (1994)..

  19. Coherent Propagation of Elementary Excitations in Solid ^4He

    NASA Astrophysics Data System (ADS)

    Goodkind, John M.; Ho, Pei-Chun

    1998-03-01

    We have measured the interaction of heat pulses and acoustic pulses propagating along orthogonal paths in solid ^4He with small amounts of ^3He impurities. The interaction is revealed as a variation of the acoustic attenuation, alpha, and velocity, v, as a function of the delay between launching of the heat pulses and the acoustic pulses. alpha and v pass through extreema at delay times corresponding to the relative propagation velocities of the acoustic waves and the excitations created by the heat pulses. The propagation velocities of the various excitations, determined in this way, are between 50 and 150 m/sec and they increase with decreasing temperature. There are two distinct peaks and a long tail at temperatures above about 500 mK indicating that more than one mode is propagating. The peak effect occurs at a different delay time for alpha than for v at temperatures near the attenuation peak (PC HO, I. P. Bindloss, and J. M. Goodkind, J. Low Temp. Phys., November 1997), providing further evidence for more than one type of propagating mode. The sign of the effect reverses as T is decreased and the change of alpha is of opposite sign to that expected from the equilibrium T dependence of alpha. We will discuss the relation of this phenomenon to previous indications of propagating modes in solid ^4He (G.A. Lengua and J. M. Goodkind, J. Low Temp. Phys., 79), 251 (1990)and to the possible Bose-Einstein condensation (PC HO, I. P. Bindloss, and J. M. Goodkind, J. Low Temp. Phys., November 1997).

  20. Formation of the weakly bound muonic molecule (4Heμt) 01 2 + in the three-body (tμ) 1 s +4He +4He collision

    NASA Astrophysics Data System (ADS)

    Czapliński, Wilhelm; Rybski, Michał

    2016-02-01

    Formation of the weakly bound muonic molecule (4Heμt) 01 2 + in the excited rotational-vibrational state (J , ν) = (0 , 1) due to the three-body collision (tμ) 1 s +4He +4He is considered for the first time. It is assumed that the process occurs in T-4He gaseous mixture in thermal equilibrium containing thermalized muonic tritium atoms. The corresponding reaction rate is calculated in the frame of the distorted wave Born approximation (DWBA) method using the dipole approximation for the interaction of tμ +4He system with the incoming helium atom. The obtained formation rate (normalized to helium density equal to the liquid hydrogen density) increases with temperature from 7.8 ṡ106 s-1 for 1000 K to 4.8 ṡ107 s-1 for 3000 K.

  1. Vortex emission from quantum turbulence in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Nago, Y.; Nishijima, A.; Kubo, H.; Ogawa, T.; Obara, K.; Yano, H.; Ishikawa, O.; Hata, T.

    2013-01-01

    An oscillating object can stretch quantized vortices attached to it in superfluids due to the relative superflow, steadily generating quantum turbulence, even in the zero-temperature limit. We report the emission and propagation of quantized vortices from quantum turbulence generated in superfluid 4He at low temperatures. A vortex-free vibrating wire enables us to detect the first collision of vortex rings and therefore to measure the time-of-flight of a vortex emitted from a generator to a detector. The detection times from the start of turbulence generation exhibit an exponential distribution, suggesting that the detection is a Poisson process. Vortices are emitted continuously, but each vortex has a random flight velocity and direction. We estimated the nondetection time and mean detection period from the distribution for two flight distances. By estimating the flight velocity, we find that only vortices with velocities lower than the detector velocity can be detected, even if the sizes of the emitted vortices are smaller than the wire thickness or the vibration amplitude. The ratio of the detection rate as a function of vortex velocity suggests anisotropic emission of vortices from the quantum turbulence.

  2. Pseudopotential theory of interacting roton pairs in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Bedell, K.; Pines, D.; Zawadowski, A.

    1984-01-01

    A configuration-space pseudopotential, which is closely related to that used by Aldrich and Pines to describe the effective interaction between background particles in 3He and 4He, is constructed and used to calculate the roton-roton scattering amplitude. From that amplitude we obtain a theory that is completely congruent with the roton-liquid theory of Bedell, Pines, and Fomin. We calculate two-roton bound states, roton-liquid parameters, and roton lifetimes, as well as information about the hybridization of the two-roton bound state with excitations of higher and lower energy. Excellent agreement between theory and experiment is obtained for the l=2 bound state at zero pair momentum, the roton lifetime, the roton contribution to the normal-fluid viscosity and the normal-fluid density, and the temperature variation of the roton energy. The effective roton-roton coupling parameters at large pair momentum are found to be an order of magnitude larger than those for small or vanishing pair momentum. At SVP we find that a substantial number of two-roton bound states of varying symmetry exist for pair momentum up to ~ 3 Å -1; at standard pressure, however the roton-roton interaction for momenta ~ 1 Å -1 is found to become repulsive, so that both the l=2 bound state at zero pair momentum and bound states at intermediate momenta are predicted to disappear under pressure.

  3. 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.

  4. 4He Thermophysical Properties: New Ab Initio Calculations

    PubMed Central

    Hurly, John J.; Mehl, James B.

    2007-01-01

    Since 2000, atomic physicists have reduced the uncertainty of the helium-helium “ab initio” potential; for example, from approximately 0.6 % to 0.1 % at 4 bohr, and from 0.8 % to 0.1 % at 5.6 bohr. These results led us to: (1) construct a new inter-atomic potential ϕ07, (2) recalculate values of the second virial coefficient, the viscosity, and the thermal conductivity of 4He from 1 K to 10,000 K, and (3), analyze the uncertainties of the thermophysical properties that propagate from the uncertainty of ϕ07 and from the Born-Oppenheimer approximation of the electron-nucleon quantum mechanical system. We correct minor errors in a previous publication [J. J. Hurly and M. R. Moldover, J. Res. Nat. Inst. Standards Technol. 105, 667 (2000)] and compare our results with selected data published after 2000. The ab initio results tabulated here can serve as standards for the measurement of thermophysical properties. PMID:27110456

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Systematics of pure and doped 4He clusters

    NASA Astrophysics Data System (ADS)

    Chin, S. A.; Krotscheck, E.

    1995-10-01

    Optimized variational calculations have been carried out for pure and doped clusters of 4He atoms up to a cluster size of N=1000 particles. For small cluster sizes with less than or equal to 112 particles, where comparisions with existing diffusion Monte Carlo results are possible, we find excellent agreement for the ground-state energy, correlation, and structure functions. For larger clusters our ground-state energies extrapolate smoothly toward a bulk limit of -7.2 K with a surface energy of 0.272 K Å-2. The resulting ground-state densities show unmistakable oscillations, confirming our earlier conclusions based on diffusion Monte Carlo studies. The present study of large clusters allows us to bridge the gap between finite systems and the bulk limit. Specifically, we show how the bulk limit of collective energies is reached as well as how the bulk Feynman spectrum is reproduced in the S-wave component of the dynamic structure function in large droplets. By plotting the collective excitation energy of higher multipole modes as a function of an effective wave number k=√scrl(scrl+1)/R, we show that the resulting spectrum can be directly compared with experimental excitation energies determined for plane liquid surfaces and films. By summing up to scrl=50 partial wave components, we show that the full dynamic structure function simultaneously displays the phonon-roton and the ripplon excitation spectrum. In the case of helium droplets doped with impurities such as rare gas atoms or the SF6 molecule, we show that the dipole collective mode becomes unstable with increased droplet size, strongly indicating that these impurities are delocalized inside large droplets. The microscopic character of the instability is revealed in the excitation functions and transition densities of the dipole mode. The introduction of impurities also profoundly alters the dynamic structure function, severely ``fragments'' the Feynman spectrum, and obliterates landmark structures such

  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. Continental degassing of 4He by surficial discharge of deep groundwater

    NASA Astrophysics Data System (ADS)

    Aggarwal, Pradeep K.; Matsumoto, Takuya; Sturchio, Neil C.; Chang, Hung K.; Gastmans, Didier; Araguas-Araguas, Luis J.; Jiang, Wei; Lu, Zheng-Tian; Mueller, Peter; Yokochi, Reika; Purtschert, Roland; Torgersen, Thomas

    2015-01-01

    Radiogenic 4He is produced by the decay of uranium and thorium in the Earth's mantle and crust. From here, it is degassed to the atmosphere and eventually escapes to space. Assuming that all of the 4He produced is degassed, about 70% of the total 4He degassed from Earth comes from the continental crust. However, the outgoing flux of crustal 4He has not been directly measured at the Earth's surface and the migration pathways are poorly understood. Here we present measurements of helium isotopes and the long-lived cosmogenic radio-isotope 81Kr in the deep, continental-scale Guarani aquifer in Brazil and show that crustal 4He reaches the atmosphere primarily by the surficial discharge of deep groundwater. We estimate that 4He in Guarani groundwater discharge accounts for about 20% of the assumed global flux from continental crust, and that other large aquifers may account for about 33%. Old groundwater ages suggest that 4He in the Guarani aquifer accumulates over half- to one-million-year timescales. We conclude that 4He degassing from the continents is regulated by groundwater discharge, rather than episodic tectonic events, and suggest that the assumed steady state between crustal production and degassing of 4He, and its resulting atmospheric residence time, should be re-examined.

  13. 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.

  14. 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

  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. Investigation of the reaction D(4He, γ)6Li at ultralow energies

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The cross section of the reaction D(4He, γ)6Li with titanium and zirconium deuterides as targets is measured for incident 4He+ ion energies of 30 and 36 keV, respectively. The ion beam is generated by a Hall pulsed plasma accelerator. For the first time, upper limits on the cross section of the reaction D(4He, γ)6Li at ultralow energies are imposed (at 90% confidence level): σ ≤ 1.2 × 10-35 cm2 for the TiD2 target and E(4He+) = 30 keV, and σ ≤ 7 × 10-36 cm2 for the ZrD2 target and E(4He+) = 36 keV

  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. 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

  19. T(T,2n)4He and 3He(3He,2p)4He: The Reaction Mechanism from Solar Energies to 10 MeV

    NASA Astrophysics Data System (ADS)

    Bacher, A. D.; Brune, C. R.; Sayre, D. B.; Hale, G. M.; Frenje, J. A.; Gatu Johnson, M.

    2016-03-01

    We have studied the energy dependence of the reaction mechanism of the T(t,2n)4He reaction at stellar energies and of its charge symmetric analog reaction 3He(3He,2p)4He at energies up 10 MeV. We find that the reaction mechanism changes dramatically over this energy range in part due to the interference of the two identical fermions in the three-body final state. This contribution is dedicated to the memory of Tom Tombrello, my Ph.D. advisor at Cal Tech, who died in 2014.

  20. Microscopic description of {sup 4}He + {sup 4}He elastic scattering over the energy range E=100-280 MeV

    SciTech Connect

    El-Azab Farid, M.

    2006-12-15

    Analysis of the differential cross sections for {sup 4}He +{sup 4}He elastic scattering is performed within the framework of the double-folding optical model. Two appropriate effective nucleon-nucleon interactions are employed to generate the {alpha}-{alpha} folded real potentials. The obtained potentials in conjunction with phenomenological Woods-Saxon (WS) derivative imaginary potentials are used to investigate six sets of the elastic scattering data through the energy range 100-280 MeV. Successful reproduction of the data is obtained by both considered interactions. In addition, real phenomenological potentials expressed in a squared WS form are successfully used to reproduce these data.

  1. 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.

  2. 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.

  3. Triple oxygen isotopic composition of the high-3He/4He mantle

    NASA Astrophysics Data System (ADS)

    Starkey, N. A.; Jackson, C. R. M.; Greenwood, R. C.; Parman, S.; Franchi, I. A.; Jackson, M.; Fitton, J. G.; Stuart, F. M.; Kurz, M.; Larsen, L. M.

    2016-03-01

    Measurements of Xe isotope ratios in ocean island basalts (OIB) suggest that Earth's mantle accreted heterogeneously, and that compositional remnants of accretion are sampled by modern, high-3He/4He OIB associated with the Icelandic and Samoan plumes. If so, the high-3He/4He source may also have a distinct oxygen isotopic composition from the rest of the mantle. Here, we test if the major elements of the high-3He/4He source preserve any evidence of heterogeneous accretion using measurements of three oxygen isotopes on olivine from a variety of high-3He/4He OIB locations. To high precision, the Δ17O value of high-3He/4He olivines from Hawaii, Pitcairn, Baffin Island and Samoa, are indistinguishable from bulk mantle olivine (Δ17OBulk Mantle - Δ17OHigh 3He/4He olivine = -0.002 ± 0.004 (2 × SEM)‰). Thus, there is no resolvable oxygen isotope evidence for heterogeneous accretion in the high-3He/4He source. Modelling of mixing processes indicates that if an early-forming, oxygen-isotope distinct mantle did exist, either the anomaly was extremely small, or the anomaly was homogenised away by later mantle convection. The δ18O values of olivine with the highest 3He/4He ratios from a variety of OIB locations have a relatively uniform composition (∼5‰). This composition is intermediate to values associated with the depleted MORB mantle and the average mantle. Similarly, δ18O values of olivine from high-3He/4He OIB correlate with radiogenic isotope ratios of He, Sr, and Nd. Combined, this suggests that magmatic oxygen is sourced from the same mantle as other, more incompatible elements and that the intermediate δ18O value is a feature of the high-3He/4He mantle source. The processes responsible for the δ18O signature of high-3He/4He mantle are not certain, but δ18O-87Sr/86Sr correlations indicate that it may be connected to a predominance of a HIMU-like (high U/Pb) component or other moderate δ18O components recycled into the high-3He/4He source.

  4. 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.

  5. Proposal for measurement of 4He II condensate - A reply to recent criticisms

    NASA Astrophysics Data System (ADS)

    Cummings, F. W.; Hyland, G. J.; Rowlands, G.

    1981-11-01

    Recent criticisms of a method to measure the temperature-dependent condensate fraction in 4He II, proposed by the authors some time ago, are assessed and found to be insufficient to discredit our procedure.

  6. Kaonic 3He and 4He X-ray measurements in SIDDHARTA

    NASA Astrophysics Data System (ADS)

    Ishiwatari, Tomoichi; Bazzi, M.; Beer, G.; Berucci, C.; Bombelli, L.; Bragadireanu, A. M.; Cargnelli, M.; Clozza, A.; Corradi, G.; Curceanu (Petrascu), C.; d'Uffizi, A.; Fiorini, C.; Ghio, F.; Girolami, B.; Guaraldo, C.; Hayano, R. S.; Iliescu, M.; Iwasaki, M.; Kienle, P.; Levi Sandri, P.; Lucherini, V.; Marton, J.; Okada, S.; Pietreanu, D.; Piscicchia, K.; Poli Lener, M.; Ponta, T.; Quaglia, R.; Rizzo, A.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Tudorache, A.; Tudorache, V.; Vazquez Doce, O.; Widmann, E.; Wünschek, B.; Zmeskal, J.

    2012-05-01

    The SIDDHARTA experiment measured the kaonic 3He and 4He 3 d →2 p X-ray transitions using gaseous targets for the first time. The strong-interaction shift both of the kaonic 3He and 4He 2 p states was determined with a precision of a few eV. The shift of kaonic 4He is much smaller than the values obtained in the experiments performed in 70's and 80's, while it is consistent with the recent result of the KEK E570 experiment, as well as the theoretical calculated values. Therefore, the problem on kaonic helium (the "kaonic helium puzzle") was definitely solved. The first observation of the kaonic 3He X-rays was also achieved in the SIDDHARTA experiment. The shift both of kaonic 3He and 4He was found to be as small as a few eV.

  7. Kaonic 3He and 4He X-ray measurements in SIDDHARTA

    NASA Astrophysics Data System (ADS)

    Ishiwatari, Tomoichi; Bazzi, M.; Beer, G.; Berucci, C.; Bombelli, L.; Bragadireanu, A. M.; Cargnelli, M.; Clozza, A.; Corradi, G.; Curceanu (Petrascu), C.; d'Uffizi, A.; Fiorini, C.; Ghio, F.; Girolami, B.; Guaraldo, C.; Hayano, R. S.; Iliescu, M.; Iwasaki, M.; Kienle, P.; Levi Sandri, P.; Lucherini, V.; Marton, J.; Okada, S.; Pietreanu, D.; Piscicchia, K.; Poli Lener, M.; Ponta, T.; Quaglia, R.; Rizzo, A.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Tudorache, A.; Tudorache, V.; Vazquez Doce, O.; Widmann, E.; Wünschek, B.; Zmeskal, J.

    The SIDDHARTA experiment measured the kaonic 3He and 4He 3d →2p X-ray transitions using gaseous targets for the first time. The strong-interaction shift both of the kaonic 3He and 4He 2p states was determined with a precision of a few eV. The shift of kaonic 4He is much smaller than the values obtained in the experiments performed in 70's and 80's, while it is consistent with the recent result of the KEK E570 experiment, as well as the theoretical calculated values. Therefore, the problem on kaonic helium (the "kaonic helium puzzle") was definitely solved. The first observation of the kaonic 3He X-rays was also achieved in the SIDDHARTA experiment. The shift both of kaonic 3He and 4He was found to be as small as a few eV.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  9. The Triple Oxygen Isotopic Composition of High 3He/4He Mantle

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Parman, S. W.; Starkey, N.; Greenwood, R.; Franchi, I.; Jackson, M. G.; Fitton, J. G.; Stewart, F. M.; Larsen, L. M.

    2015-12-01

    Measurements of Xe isotope ratios in ocean island basalts (OIB) suggest that Earth's mantle accreted heterogeneously, and that compositional remnants of accretion are sampled by modern, high-3He/4He OIB associated with the Icelandic and Samoan plumes [1]. If so, the high-3He/4He source may also have a distinct oxygen isotopic composition from the rest of the mantle. Here, we test if the major elements of the high-3He/4He source preserve any evidence of heterogeneous accretion using measurements of three oxygen isotopes on olivine from a variety of high-3He/4He OIB locations. To high precision, the ∆17O value of high-3He/4He olivines from Hawaii, Pitcairn, Baffin Island and Samoa, are indistinguishable from bulk mantle olivine (Δ17OBulk Mantle - Δ17OHigh 3He/4He olivine = -0.002 ± 0.004 (2 x SEM) ‰). Thus, there is no resolvable oxygen isotope evidence for heterogeneous accretion in the high-3He/4He source. Modelling of mixing processes indicates that if an early-forming, oxygen-isotope distinct mantle did exist, either the anomaly was extremely small, or the anomaly was homogenised away by later mantle convection. The δ18O values of olivine with the highest 3He/4He ratios from a variety of OIB locations have a relatively uniform composition (~5 ‰). This composition is intermediate to values associated with the depleted MORB mantle and the average mantle. Similarly, δ18O values of olivine from high-3He/4He OIB correlate with radiogenic isotope ratios of He, Sr, and Nd. Combined, this suggests that oxygen remains coupled to the more incompatible elements during melt production and migration and that the intermediate δ18O value is a feature of the mantle source. The processes responsible for the δ18O signature of high-3He/4He mantle are not certain, but δ18O-87Sr/86Sr correlations indicate that it may be connected to a predominance of a HIMU-like (high U/Pb) component or other moderate δ18O components recycled into the high-3He/4He source. [1] S

  10. Effect of confinement on phase-separation and superfluid transition in ^3 He-^4 He mixtures

    NASA Astrophysics Data System (ADS)

    Shenoy, V. B.; Saam, W. F.

    1996-03-01

    We derive the phase diagram of ^3 He - ^4 He mixtures confined between parallel plates within phenomelogical Landau theory. The analyses focus on the effect of the separation between the plates and the magnitude of surface field ( which is a measure of preference for ^4He rich phase) on phase-separation and superfluid transition in the confined mixtures. Connection to recent experiments on He mixtures in aerogel is made.

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

    NASA Astrophysics Data System (ADS)

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

    1996-01-01

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

  12. 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.

  13. A high-temperature supersolid of 4He in a one-dimensional periodic potential

    DOE PAGESBeta

    Olsen, Raina J

    2015-01-01

    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. The properties of experimentally achievable materials which could support this type of supersolid are also discussed.« less

  14. Elementary Excitations in Solid and Liquid 4He at the Melting Pressure

    NASA Astrophysics Data System (ADS)

    Todoshchenko, I. A.; Alles, H.; Junes, H. J.; Manninen, M. S.; Parshin, A. Y.; Tsepelin, V.

    2008-02-01

    Recent discovery of a nonclassical rotational inertia (NCRI) in solid 4He below 0.2 K by Kim and Chan has revived great interest in the problem of supersolidity and initiated intensive study on the properties of solid 4He. A direct proof that the onset of NCRI corresponds to the supersolid transition would be the observation of a corresponding drop of the entropy of solid 4He below the transition temperature. We have measured the melting pressure of ultrapure 4He in the temperature range from 0.01 to 0.45 K with several single crystals grown at different pressures and with the accuracy of 0.5 μbar. In addition, supplementary measurements of the pressure in liquid 4He at constant volume have been performed, which allowed us to eliminate the contribution of the temperature-dependent properties of the pressure gauge from the measured melting pressure data. With the correction to the temperature-dependent sensitivity of the pressure gauge, the variation of the melting pressure of 4He below 320 mK obeys the pure T 4 law due to phonons with the accuracy of 0.5 μbar, and no sign of the transition is seen (Todoshchenko et al. in JETP Lett. 85:454, 2007). This sets the upper limit of ˜5ṡ10-8 R for a possible excess entropy in high-quality 4He crystals below 320 mK. At higher temperatures the contribution from rotons in the superfluid 4He has been observed. The thermal expansion coefficient of the superfluid 4He has been measured in the range from 0.01 to 0.7 K with the accuracy of ˜10-7 1/K, or by two orders of magnitude better than in previous measurements. The roton contributions to the melting pressure and to the pressure in liquid at a constant volume are consistent and yield the value of 6.8 K for the roton gap, which is very close to the values obtained with other methods. As no contribution due to weakly interacting vacancies to the melting pressure of 4He has been observed, the lower limit of about 5.5 K for their activation energy can be set.

  15. Trojan horse particle invariance studied with the {sup 6}Li(d,{alpha}){sup 4}He and {sup 7}Li(p,{alpha}){sup 4}He reactions

    SciTech Connect

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

    2011-04-15

    The Trojan horse nucleus invariance for the binary reaction cross section extracted from the Trojan horse reaction was tested using the quasifree {sup 3}He({sup 6}Li,{alpha}{alpha})H and {sup 3}He({sup 7}Li,{alpha}{alpha}){sup 2}H reactions. The cross sections for the {sup 6}Li(d,{alpha}){sup 4}He and {sup 7}Li(p,{alpha}){sup 4}He binary processes were extracted in the framework of the plane wave approximation. They are compared with direct behaviors as well as with cross sections extracted from previous indirect investigations of the same binary reactions using deuteron as the Trojan horse nucleus instead of {sup 3}He. The very good agreement confirms the applicability of the plane wave approximation which suggests the independence of the binary indirect cross section on the chosen Trojan horse nucleus, at least for the investigated cases.

  16. Vibrational effects in a weakly-interacting quantum solvent: The CO molecule in 4He gas and in 4He droplets

    NASA Astrophysics Data System (ADS)

    Paesani, F.; Gianturco, F. A.

    2002-06-01

    The coupling between the intermolecular motion and the internal vibrational coordinate in the He-CO system is computed at the post-Hartree-Fock level using the DFT+DISP model already employed by us for similar systems and reviewed here in the main text. The quality of the computation of such weak effects is compared with other, earlier model calculations and then used for the evaluation of the vibrational relaxation cross sections of the CO molecule diluted in 4He gas. A further assessment of the vibrational coupling is carried out by computing, with a stochastic approach that employs the Diffusion Monte Carlo method, the effects on the vibrational frequency of the CO impurity from its immersion in 4He droplets of variable size. Both sets of results are analyzed and discussed to gauge the reliability of the computed coupling vis-a-vis one of those suggested by earlier calculations. This study provides further evidence on the difficulty of quantitatively obtaining from calculations the extremely small effects connected with molecular vibrational features in this system and caused by the weak interaction between the title molecule and a quantum solvent like 4He.

  17. Measurements on the melting curve of ^4He down to 10 mK

    NASA Astrophysics Data System (ADS)

    Alles, Harry

    2007-03-01

    Recent discovery of a nonclassical rotational inertia in solid ^4He below about 0.2 K by Kim and Chan has initiated an intensive study on the properties of solid ^4He. As Kim and Chan have interpreted their observation as the evidence of supersolid behavior, we have decided to measure very accurately the melting curve of ^4He because, as the slope of the melting curve is proportional to the difference in the entropy of the liquid and solid phases, there should be an anomaly at the possible supersolid transition. We have measured the melting curve of ^4He with the accuracy of about 0.5 microbar with ^4He crystals which had various concentration of defects. All our samples showed only the expected T^4 dependence due to phonons without any sign of the supersolid transition in the temperature range of 80400 mK. Below 80 mK we observed a small deviation from T^4 dependence which, however, cannot be attributed to the supersolid transition because our recent measurements with the cell containing liquid sample only suggest that this deviation is by the temperature variation of properties of BeCu membrane of our capacitive pressure gauge. In addition to our published data with ^4He of natural purity [Phys. Rev. Lett. 97, 165302 (2006)] we also report our recent measurements of the melting curve with ultra pure ^4He (0.3 ppb of ^3He impurities). In these measurements we followed optically the shape of the sample crystals which had very good quality.

  18. Torsional oscillator studies for possible supersolidity in two-dimensional 4He solid

    NASA Astrophysics Data System (ADS)

    Shibayama, Y.; Fukuyama, H.; Shirahama, K.

    2009-02-01

    The origin of "supersolidity" of solid 4He, which was reported by Kim and Chan, has not yet been clarified. Although Bose-Einstein condensation of zero-point vacancies (ZPVs) was initially considered to be a possible origin, recent studies imply that crystal imperfections in the solid samples are strongly associated with the observed supersolid behaviors. In two-dimensional (2D) 3He system on graphite, on the other hand, a novel phase due to quantum hopping of ZPVs has been found. This suggests that ZPVs form also in 2D 4He solid systems and their quantum hopping results in superfluidity of ZPVs, namely, supersolidity. In order to search for the possible 2D supersolid state, we perform torsional oscillator studies for 4He films adsorbed on graphite. At the 4He coverage of 18.7 nm-2 a positive frequency shift was observed below 300 mK. The size of the shift decreases with increasing the oscillation velocity. This behavior closely resembles to the supersolid behavior of bulk solid 4He.

  19. 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.

  20. Theoretical Basis for Anomalous Heat and ^4He in Deuterium-Metal Systems

    NASA Astrophysics Data System (ADS)

    Chubb, Scott; Chubb, Talbot

    2000-03-01

    Because electromagnetic (E.M.) forces have infinite range, reactions exist in which the degrees of freedom associated with nuclear- and atomic- scales are coupled. Although such non-separable reactions are possible in conventional D+D fusion, they rarely occur because the relevant E.M.-induced reaction (D+Darrow ^4He) violates the rules of energy-momentum conservation (EMC) at-a-point, except when a high momentum (HM) gamma ray is emitted. When D^+ and ^4He^+^+ occupy ion band states with low concentration, however, different forms of E.M. coupling become possible in which EMC is violated locally but conserved globally and D+Darrow ^4He reactions occur without HM particles(http: //www.aps.org/meet/CENT99/BAPS/abs/S9500.html). Using a generalized KKR-Multiple-Scattering theory, we have formulated Generalized Kadanoff-Baym Equations ( D.C. Langreth and J.W. Wilkins, Phys. Rev. B 6), 3189 (1972). that describe the associated non-local heat and ^4He release from the resulting coupling between nuclear interactions, D^+ and ^4He^+^+ ion band states, and electrons.

  1. Anomalous Elasticity of 4He Films at the Quantum Phase Transition

    NASA Astrophysics Data System (ADS)

    Shirahama, Keiya; Takahashi, Daisuke; Kogure, Takayuki; Yoshimura, Hitomi; Higashino, Rama

    4 He films on solid substrates exhibit a quantum phase transition between localized (nonsuperfluid) and superfluid states by changing coverage n. We have made torsional oscillator (TO) studies for 4He films adsorbed on nanoporous glasses. A TO with localized films showed an apparent ''supersolid'' behavior, an increase in TO frequency f with broad peak in Q-1. Combining with FEM analyses for TO's with different designs, we conclude that the behavior results from the softening of adsorbed 4He films at high temperatures. The features in f and Q-1 are fitted well to a Debye-like activation with a distributed energy gap Δ, so the elasticity is accounted by thermal excitation of localized atoms to an ''extended'' state. As the critical coverage nc approaches the gap decreases to zero with a powerlaw Δ ~(n -nc) 1 . 2 . Assuming that the 4He chemical potential μ (n) is located in the middle of the gap, we can estimate the elastic constant κ-1 =n2 ∂μ / ∂n . The elasticity agrees with shear moduli of 4He films obtained from the FEM analysis within factor of three. The energetics proposed from the elastic behavior naturally explains other properties of He films adsorbed on disordered substrates.

  2. 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. PMID:27300963

  3. Van der Waals correlation between two 4He monolayers on the opposite sides of graphene

    NASA Astrophysics Data System (ADS)

    Kwon, Yongkyung

    2015-06-01

    Path-integral Monte Carlo calculations have been performed to study the correlation between two 4He monolayers adsorbed on opposite sides of a graphene sheet. Here, the 4He-substrate interaction is described by the pairwise sum of the 4He-C interatomic potentials. We employ two different anisotropic 4He-C pair potentials proposed to fit the helium scattering data on a graphite surface, namely, a 6-12 Lennard-Jones potential and a Yukawa-6 potential. With the Lennard-Jones substrate potential, we do not observe any noticeable correlation between two oppositeside 4He monolayers, which is consistent with the prediction of the previous theoretical studies based on the same substrate potential. When the Yukawa-6 substrate potential is used, however, two incommensurate triangular solids, which are realized at the first-layer completion density of 0.12 Å -2, are found to favor an AA stacking order, two triangular lattices on top of each other, over an AB stacking. Finally, the effects of this interlayer correlation on the formation of stable mobile vacancies are discussed.

  4. 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.

  5. 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).

  6. Study of Supersolidity and Shear Modulus Anomaly of 4He in a Triple Compound Oscillator

    NASA Astrophysics Data System (ADS)

    Mi, Xiao; Mueller, Erich J.; Reppy, John D.

    2012-12-01

    The recently discovered shear modulus anomaly in solid 4He bears a strong similarity to the phenomenon of supersolidity in solid 4He and can lead to the period shift and dissipative signals in torsional oscillator experiments that are nearly identical to the classic NCRI signals observed by Kim and Chan. In the experiments described here, we attempt to isolate the effects of these two phenomena on the resonance periods of torsion oscillators. We have constructed a triple compound oscillator with distinct normal modes. We are able to demonstrate that, for this oscillator, the period shifts observed below 200 mK have their primary origin in the temperature dependence of the shear modulus of the solid 4He sample rather than the formation of a supersolid state.

  7. 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.

  8. High-sensitivity measurement of 3He-4He isotopic ratios for ultracold neutron experiments

    NASA Astrophysics Data System (ADS)

    Mumm, H. P.; Huber, M. G.; Bauder, W.; Abrams, N.; Deibel, C. M.; Huffer, C. R.; Huffman, P. R.; Schelhammer, K. W.; Janssens, R.; Jiang, C. L.; Scott, R. H.; Pardo, R. C.; Rehm, K. E.; Vondrasek, R.; Swank, C. M.; O'Shaughnessy, C. M.; Paul, M.; Yang, L.

    2016-06-01

    Research efforts ranging from studies of solid helium to searches for a neutron electric dipole moment require isotopically purified helium with a ratio of 3He to 4He at levels below that which can be measured using traditional mass spectroscopy techniques. We demonstrate an approach to such a measurement using accelerator mass spectroscopy, reaching the 10-14 level of sensitivity, several orders of magnitude more sensitive than other techniques. Measurements of 3He/4He in samples relevant to the measurement of the neutron lifetime indicate the need for substantial corrections. We also argue that there is a clear path forward to sensitivity increases of at least another order of magnitude.

  9. Kosterlitz-Thouless Transition in 4He Films Adsorbed to Rough Calcium Fluoride

    SciTech Connect

    Luhman, D. R.; Hallock, R. B.

    2006-09-07

    Previous measurements in our lab have shown that the onset of superfluidity at the KT transition, typically seen as a sharp change in the frequency of a smooth-surface quartz crystal microbalance, becomes less identifiable in the presence of increasing surface roughness or disorder, while the peak in the dissipation is unchanged. Using a series of microbalances coated with increasingly rough CaF2, we have extended our measurements to lower 4He film coverages and thus lower temperatures. We find at lower 4He coverages that the presence of disorder on the substrate has a diminished effect on the frequency shift.

  10. Explosion of electron bubbles attached to quantized vortices in liquid {sup 4}He

    SciTech Connect

    Pi, Marti; Mayol, Ricardo; Hernando, Alberto; Barranco, Manuel; Ancilotto, Francesco

    2007-06-28

    Electron bubbles in superfluid {sup 4}He have been recently observed in low-temperature cavitation measurements under experimental conditions where quantized vortices are also present in the liquid, and which might be attached to the bubbles. We have calculated, within density functional theory, the structure and energetics of electron bubbles pinned to linear vortices in liquid {sup 4}He at low temperature, and the pressure at which such structures become mechanically unstable. Our results are in semiquantitative agreement with the experiments. We discuss dynamical effects not included in the theoretical model used in the present calculations, and which could explain some discrepancies between our results and the experimental data.

  11. Search for anisotropy in the Debye-Waller factor of HCP solid 4He

    NASA Astrophysics Data System (ADS)

    Barnes, Ashleigh L.; Hinde, Robert J.

    2016-02-01

    The properties of hexagonal close packed (hcp) solid 4He are dominated by large atomic zero point motions. An accurate description of these motions is therefore necessary in order to accurately calculate the properties of the system, such as the Debye-Waller (DW) factors. A recent neutron scattering experiment reported significant anisotropy in the in-plane and out-of-plane DW factors for hcp solid 4He at low temperatures, where thermal effects are negligible and only zero-point motions are expected to contribute. By contrast, no such anisotropy was observed either in earlier experiments or in path integral Monte Carlo (PIMC) simulations of solid hcp 4He. However, the earlier experiments and the PIMC simulations were both carried out at higher temperatures where thermal effects could be substantial. We seek to understand the cause of this discrepancy through variational quantum Monte Carlo simulations utilizing an accurate pair potential and a modified trial wavefunction which allows for anisotropy. Near the melting density, we find no anisotropy in an ideal hcp 4He crystal. A theoretical equation of state is derived from the calculated energies of the ideal crystal over a range of molar volumes from 7.88 to 21.3 cm3, and is found to be in good qualitative agreement with experimental data.

  12. Search for anisotropy in the Debye-Waller factor of HCP solid (4)He.

    PubMed

    Barnes, Ashleigh L; Hinde, Robert J

    2016-02-28

    The properties of hexagonal close packed (hcp) solid (4)He are dominated by large atomic zero point motions. An accurate description of these motions is therefore necessary in order to accurately calculate the properties of the system, such as the Debye-Waller (DW) factors. A recent neutron scattering experiment reported significant anisotropy in the in-plane and out-of-plane DW factors for hcp solid (4)He at low temperatures, where thermal effects are negligible and only zero-point motions are expected to contribute. By contrast, no such anisotropy was observed either in earlier experiments or in path integral Monte Carlo (PIMC) simulations of solid hcp (4)He. However, the earlier experiments and the PIMC simulations were both carried out at higher temperatures where thermal effects could be substantial. We seek to understand the cause of this discrepancy through variational quantum Monte Carlo simulations utilizing an accurate pair potential and a modified trial wavefunction which allows for anisotropy. Near the melting density, we find no anisotropy in an ideal hcp (4)He crystal. A theoretical equation of state is derived from the calculated energies of the ideal crystal over a range of molar volumes from 7.88 to 21.3 cm(3), and is found to be in good qualitative agreement with experimental data. PMID:26931710

  13. The Quest for Bose-Einstein Condensation in Solid 4He

    NASA Astrophysics Data System (ADS)

    Diallo, S. O.; Azuah, R. T.; Glyde, H. R.

    2011-03-01

    Ever since the seminal torsional oscillator (TO) measurements of Kim and Chan which suggested the existence of a phase transition in solid 4He, from normal to a `supersolid' state below a critical temperature T c = 200 mK, there has been an unprecedented amount of excitement and research activity aimed at better understanding this phase. Despite much work, this remarkable phase has yet to be independently confirmed by conventional scattering techniques, such as neutron scattering. We have carried out a series of neutron scattering measurements, which we here review, aimed at observing Bose-Einstein condensation (BEC) in solid 4He at temperatures below T c . In bulk liquid 4He, the appearance of BEC below T λ signals the onset of superfluidity. The observation of a condensate fraction in the solid would provide an unambiguous confirmation for `supersolidity'. Although, our measurements have not yet revealed a non-zero condensate fraction or algebraic off diagonal long-range order n 0 in solid 4He down to 65 mK, i.e. n 0=(0±0.3)%, our search for BEC and its corollaries continues with improved instrumentation.

  14. Search for supersolid 4He in neutron scattering experiments at ISIS

    NASA Astrophysics Data System (ADS)

    Kirichek, O.

    2009-02-01

    The observation of a non-classical rotation inertia (NCRI) fraction in bulk solid 4He by M. Chan and E. Kim [1, 2] attracted significant interest as a possible manifestation of supersolid state of matter. Despite numerous experimental and theoretical studies inspired by this observation, an explicit explanation for this phenomenon is still missing. Neutron scattering experiments on solid helium may help to shed light on the physical grounds of NCRI and answer the question on whether this phenomenon could be caused by Bose-Einstein Condensation. In this paper we are going to discuss the results obtained in experiments involving neutron scattering on solid 4He. Microscopic quantitative data such as mean kinetic energy, mean square momentum and mean square displacement of helium atoms as well as the lattice parameter have been obtained for the first time for solid 4He in temperature range 70mK - 500 mK. No change was seen in the single atom kinetic energy (within statistical error better than 1%) as well as change in the lattice parameter (within 0.03%). The mean square displacement did not change in the region of expected supersolid transition either. All these results suggest that the NCRI transition is quite different from the superfluid transition in liquid 4He.

  15. Finding the Missing γ in D+Darrow ^4He Cold Fusion Excess Heat:

    NASA Astrophysics Data System (ADS)

    Chubb, Scott

    2002-03-01

    The source of Cold Fusion (CF)Excess Heat is a novel form of D+Darrow ^4He reaction in which no high energy γ rays are emitted (http:// www.aps.org/meet/MAR01/baps/abs/S7640003.html) . An important source of confusion concerning this point is the apparent lack of consensus about known effects associated even with the conventional D+Darrow^4He+γ reaction. In fact, although little information about D+Darrow ^4He+γ appears in the conventional fusion literature, the photo-dissociation reaction ^4He+γarrowD+D not only has been widely studied but is known to occur through a quadrupolar (E2) transition in which the two particle wave function associated with the D-nuclei is required to preserve Bose symmetry, in the far field regions, where the Electromagnetic Interaction EMI is dominant. Also in this reaction coupling occurs between strong and EMI's that invalidates the separability requirements that are present in the remaining D+D fusion reactions. These facts lend credibility to the notion that coherent many-body effects, involving D-exchange can alter the reaction in such a way that γ ray emission is not required.

  16. The ABC Effect in the Double-Pionic Fusion to 4He.

    NASA Astrophysics Data System (ADS)

    Pricking, A.

    2010-04-01

    The double-pionic fusion to 4He was measured exclusively and kinematically complete with the WASA 4π detector at COSY for the reactions dd →4Heπ0π0 and dd →4Heπ+π- . The measurements were performed over the full energy region, where the so-called ABC effect was observed previously in inclusive measurements. Whereas the latter exhibit not only a low-mass enhancement - the ABC-effect - in the 4He missing mass spectrum but also a prominent high-mass enhancement, we observe only a very strong low-mass enhancement and no pronounced high mass enhancement. This is in contrast to theoretical predictions based on t-channel ∆∆ excitation. Also the energy dependence of the observed total cross section does not fit to such predictions. Both features, however, agree very well with the observations in the most basic double-pionic fusion process in the isoscalar channel pn → dπ0π0.

  17. Electron screening in the {sup 3}He(d,p){sup 4}He reaction

    SciTech Connect

    Barker, F. C.

    2007-02-15

    A reanalysis of data for the {sup 3}He(d,p){sup 4}He reaction obtained using the Trojan-horse method, together with data from a direct measurement, leads to an electron-screening potential that is not consistent with the adiabatic limit, but it is consistent with a previous value from different data.

  18. A non-perturbative approach to freezing of superfuid 4He in density functional theory

    NASA Astrophysics Data System (ADS)

    Minoguchi, T.; Galli, De; Rossi, M.; Yoshimori, A.

    2012-12-01

    Freezing of various classical liquids is successfully described by density functional theory (DFT). On the other hand, so far no report has been published that DFT describes the freezing of superfuid 4He correctly. In fact, DFT gives too stable solid phase and the superfuid phase does not exist at finite positive pressures within a second order perturbation. In this paper we try a non-perturbative version of DFT, that is modified weighted density approximation (MWDA) to go beyond second order perturbation for the freezing of superfuid 4He. Via an exact zero temperature quantum Monte-Carlo (QMC) method we have computed the equation of state and the compressibility of superfuid 4He. By utilizing a recently introduced analytic continuation method (the GIFT method), we have obtained also density response functions at different densities from QMC imaginary time correlation functions. Contrary to second order perturbation, by employing these QMC data as DFT input we find a too stable superfuid phase, preventing freezing around the experimentally observed freezing pressure. We find the same pathological behavior by using another model energy functional of superfuid 4He (Orsay-Trento model). We conclude that the straightforward MWDA calculation gives such a poor result when liquid-gas transition is present.

  19. 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.

  20. ^4 He Crystals in Reduced Gravity Obtained by Parabolic Flights of a Jet Plane

    NASA Astrophysics Data System (ADS)

    Takahashi, Takuya; Nomura, Ryuji; Okuda, Yuichi

    2016-03-01

    ^4 He 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 ^4 He crystals at ultralow temperatures by developing a specially designed ^3 He-^4 He dilution refrigerator compatible with the experimental restrictions in a small jet plane. ^4 He 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.

  1. 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.

  2. 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. PMID:26601315

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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

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

    PubMed

    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 (4)He, 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 (4)He 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 (4)He 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 (4)He 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 (4)He 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

  9. 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

  10. Dislocation densities and lengths in solid 4He from elasticity measurements

    NASA Astrophysics Data System (ADS)

    Haziot, Ariel; Fefferman, Andrew D.; Beamish, John R.; Balibar, Sébastien

    2013-02-01

    Measurements on solid 4He show large softening of the shear modulus due to dislocations, behavior which has been described as giant plasticity. Dislocation networks may also be responsible for the unusual behavior seen in torsional oscillator and flow experiments. However, previous estimates of dislocation densities vary by many orders of magnitude, even in single crystals grown under similar conditions. By measuring the temperature and frequency dependencies of the elastic dissipation, we have determined dislocation densities and network lengths in 4He single crystals, both in coexistence with liquid and at higher pressures, and in polycrystals grown at constant density. In all cases, dislocation lengths are much longer and the networks are less connected than previous estimates. Even in polycrystals, the dislocation network is far too sparse to explain the torsional oscillator results in terms of superfluidity in a dislocation network.

  11. 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

  12. Critical Casimir force in 4He films: confirmation of finite-size scaling.

    PubMed

    Ganshin, A; Scheidemantel, S; Garcia, R; Chan, M H W

    2006-08-18

    We present new capacitance measurements of critical Casimir force-induced thinning of 4He films near the superfluid transition, focused on the region below Tlambda where the effect is the greatest. 4He films of 238, 285, and 340 A thickness are adsorbed on atomically smooth, N-doped silicon substrates. The Casimir force scaling function theta, deduced from the thinning of these three films, collapses onto a single universal curve, attaining a minimum theta=-1.30+/-0.03 at x=td1/nu=-9.7+/-0.8 A1/nu. The collapse confirms the finite-size scaling origin of the dip in the film thickness. Separately, we also confirm the presence down to 2.13 K of the Goldstone or surface fluctuation force, which makes the superfluid film approximately 2 A thinner than the normal film. PMID:17026241

  13. A discussion of the dispersion curve of energy excitations in liquid 4He

    NASA Astrophysics Data System (ADS)

    Bogoyavlenskii, I. V.; Puchkov, A. V.; Skomorokhov, A. N.; Karnatsevich, L. V.

    2004-10-01

    An investigation of the dispersion of excitations in a quantum liquid, superfluid 4He, is carried out. An attempt is made to systematize the published experimental data that indicate a substantially different nature of excitations with wave vectors corresponding to different parts of the dispersion curve of liquid 4He. Neutron spectroscopy data are analyzed in relation to a certain physical hypothesis concerning the formation of such a spectrum, and it is found that the majority of the known experimental facts can be explained in framework of that hypothesis. Particular attention is paid to a comparison of the experimental data obtained on the DIN-2PI time-of-flight spectrometer (at the IBR-2 Reactor, Dubna) with the results obtained at foreign research centers.

  14. 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.

  15. Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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 4He/3He thermochronometry data from the Grand Canyon basement that tightly constrain the near-surface cooling history associated with canyon incision. 4He/3He 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. No Effect of Steady Rotation on Solid ^4He in a Torsional Oscillator

    NASA Astrophysics Data System (ADS)

    Fear, M. J.; Walmsley, P. M.; Zmeev, D. E.; Mäkinen, J. T.; Golov, A. I.

    2016-05-01

    We have measured the response of a torsional oscillator containing polycrystalline hcp solid 4He to applied steady rotation in an attempt to verify the observations of several other groups that were initially interpreted as evidence for macroscopic quantum effects. The geometry of the cell was that of a simple annulus, with a fill line of relatively narrow diameter in the centre of the torsion rod. Varying the angular velocity of rotation up to 2 rad s^{-1} showed that there were no step-like features in the resonant frequency or dissipation of the oscillator and no history dependence, even though we achieved the sensitivity required to detect the various effects seen in earlier experiments on other rotating cryostats. All small changes during rotation were consistent with those occurring with an empty cell. We thus observed no effects on the samples of solid ^4He attributable to steady rotation.

  17. Maximum supercoolign in liquid /sup 3/He-/sup 4/He mixtures near the tricritical point

    SciTech Connect

    Sinha, D.N.; Hoffer, J.K.

    1984-01-01

    Measurements of supercooling in liquid /sup 3/He-/sup 4/He mixtures near the tricritical point are presented. The reduced temperature range 0.001 < epsilon identical to (1 - T/T/sub t/) < 0.01 was investigated for three different rates of cooling using a pressure-quench technique. For epsilon < 0.012, the maximum supercooling was found to be a function of the cooling rate. Comparisons with data in organic binary mixtures are given.

  18. 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.

  19. 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.

  20. Charge-induced instability of the /sup 4/He solid-superfluid interface

    SciTech Connect

    Savignac, D.; Leiderer, P.

    1982-12-20

    The interface between crystalline and superfluid /sup 4/He, when charged with negative ions, is deformed as a result of melting and crystallization processes. As long as the electric field normal to the interface is below a critical value, the deformation is stable and reversible. Above the critical field a charge-induced instability of the crystal is observed, which resembles the electrohydrodynamic instability of liquid surfaces.

  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. 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.}

  4. Selective adsorption of 4He on the NaCl(001) surface

    NASA Astrophysics Data System (ADS)

    Leung, W. Y.; Larese, J. Z.; Frankl, D. R.

    1984-01-01

    The diffraction of 4He nozzle beams at several energies from cleaved (001) surfaces of NaCl has been studied. Resonance features are identified and give binding energies of 4.1 ± 0.1, 1.5 ± 0.1 and 0.3 ± 0.15 meV. One feature suggests an energy of 5 meV, but this is unsubstantiated. The resonance signatures are in disagreement with elastic scattering theories.

  5. Combination of a 3He/ 4He dilution refrigerator and an ESR spectrometer

    NASA Astrophysics Data System (ADS)

    von Spalden, Y.; Baberschke, K.

    1981-08-01

    We report the combination of a 3He/ 4He dilution refrigerator with ESR spectrometers of 1,3 and 9 GHz. Since only the sample is cooled down to Millikelvin, the microwave-frequency frequency setup can be changed very eaily during an experiment. The ESR intensities of a Au167 Er and a AuEr sample were used to calibrate the temperature of the sample.

  6. 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

  7. 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.

  8. Observation of Non-Classical Rotational Inertia in Bulk Solid 4He

    NASA Astrophysics Data System (ADS)

    Kondo, Motoshi; Takada, Shunichi; Shibayama, Yoshiyuki; Shirahama, Keiya

    2007-09-01

    In recent torsional oscillator experiments by Kim and Chan (KC), a decrease of rotational inertia has been observed in solid 4He in porous materials (Kim, E., Chan, M.H.W. in Nature 427:225, 2004; J. Low Temp. Phys. 138:859, 2005) and in a bulk annular channel (Kim, E., Chan, M.H.W. in Science 305:1941, 2004). This observation strongly suggests the existence of “non-classical rotational inertia” (NCRI), i.e. superflow, in solid 4He. In order to study such a possible “supersolid” phase, we perform torsional oscillator experiments for cylindrical solid 4He samples. We have observed decreases in rotational inertia below 200 mK for two solid samples (pressures P=4.1 and 3.0 MPa). The observed NCRI fraction at 70 mK is 0.14%, which is about 1/3 of the fraction observed in the annulus by KC. Our observation is the first experimental confirmation of the possible supersolid finding by KC.

  9. 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.

  10. Superfluid Onset of 4He Nanotube Depending on a One-Dimensional Length

    NASA Astrophysics Data System (ADS)

    Matsushita, T.; Shinohara, A.; Hieda, M.; Wada, N.

    2016-05-01

    A 1D Bose fluid has been actually realized for the 4 He nanotubes formed in 1D nanochannels, and the superfluidity observed by a torsional oscillator. Dependence of the superfluid density on the channel diameter was qualitatively well explained by a theory that the superfluid onset temperature depends on an effective 1D length L_{eff} which is the ratio of the length to the circumference of the fluid nanotube. To examine this mechanism, we measured the superfluid of a new 4 He nanotube formed in the 1D channel with the diameter 3.1 nm and the length 10-20 \\upmu m, which is one order longer than that of the former channels. The observed superfluid is similar to that of the much smaller diameter, typically 2.2 or 1.8 nm, channel with the shorter length. This indicates that the superfluid onset observed for the present 4He nanotubes is determined by the finite effective 1D length L_{eff}, not by the channel diameter. In addition to this length dependence, dynamics at the 1D superfluid onset is indicated by a dissipation peak at 103 Hz measurement frequency.

  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. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  16. Shell-model description of the charge form factor and the first excited state in /sup 4/He

    SciTech Connect

    Bevelacqua, J.J.

    1982-09-01

    A /sup 4/He shell-model formalism, including two- and three-body forces, is used to calculate ground and first excited state properties. Inclusion of the three-body force improves the calculated ground state rms radius, ground state form factor, and position of the /sup 4/He first excited state.

  17. Use of correlated potential harmonic basis functions for the description of the {sup 4}He trimer and small clusters

    SciTech Connect

    Das, Tapan Kumar; Chakrabarti, Barnali; Canuto, Sylvio

    2011-04-28

    A correlated many-body basis function is used to describe the {sup 4}He trimer and small helium clusters ({sup 4}He{sub N}) with N= 4 - 9. A realistic helium dimer potential is adopted. The ground state results of the {sup 4}He dimer and trimer are in close agreement with earlier findings. But no evidence is found for the existence of Efimov state in the trimer for the actual {sup 4}He-{sup 4}He interaction. However, decreasing the potential strength we calculate several excited states of the trimer which exhibit Efimov character. We also solve for excited state energies of these clusters which are in good agreement with Monte Carlo hyperspherical description.

  18. 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.

  19. Properties of 4He and 6Li with improved chiral EFT interactions

    NASA Astrophysics Data System (ADS)

    Maris, P.; Binder, S.; Calci, A.; Epelbaum, E.; Furnstahl, R. J.; Golak, J.; Hebeler, K.; Kamada, H.; Krebs, H.; Langhammer, J.; Liebig, S.; Meißner, U.-G.; Minossi, D.; Nogga, A.; Potter, H.; Roth, R.; Skibiński, R.; Topolnicki, K.; Vary, J. P.; Witala, H.

    2016-03-01

    We present recent results for 4He and 6Li obtained with improved NN interactions derived from chiral effective field theory up to N4LO. The many-body calculations are performed order-by-order in the chiral expansion. At N3LO and N4LO additional renormalization using the Similarity Renormalization Group is adopted to improve numerical convergence of the many-body calculations. We discuss results for the ground state energies, as well as the magnetic moment and the low-lying spectrum of 6Li.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  2. 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.

  3. 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.

  4. Superfluidity, Bose condensation and neutron scattering in liquid {sup 4}He

    SciTech Connect

    Silver, R.N.

    1997-04-01

    The relation between superfluidity and Bose condensation in {sup 4}He provides lessons that may be valuable in understanding the strongly correlated electron system of high {Tc} superconductivity. Direct observation of a Bose condensate in the superfluid by deep inelastic neutron scattering measurements has been attempted over many years. But the impulse approximation, which relates momentum distributions to neutron scattering structure functions, is broadened by final state effects. Nevertheless, the excellent quantitative agreement between ab initio quantum many body theory and high precision neutron experiments provides confidence in the connection between superfluidity and Bose condensation.

  5. 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.}

  6. Candidate Resonant Tetraneutron State Populated by the 4He (8H3, 8Be) ) Reaction

    NASA Astrophysics Data System (ADS)

    Kisamori, K.; Shimoura, S.; Miya, H.; Michimasa, S.; Ota, S.; Assie, M.; Baba, H.; Baba, T.; Beaumel, D.; Dozono, M.; Fujii, T.; Fukuda, N.; Go, S.; Hammache, F.; Ideguchi, E.; Inabe, N.; Itoh, M.; Kameda, D.; Kawase, S.; Kawabata, T.; Kobayashi, M.; Kondo, Y.; Kubo, T.; Kubota, Y.; Kurata-Nishimura, M.; Lee, C. S.; Maeda, Y.; Matsubara, H.; Miki, K.; Nishi, T.; Noji, S.; Sakaguchi, S.; Sakai, H.; Sasamoto, Y.; Sasano, M.; Sato, H.; Shimizu, Y.; Stolz, A.; Suzuki, H.; Takaki, M.; Takeda, H.; Takeuchi, S.; Tamii, A.; Tang, L.; Tokieda, H.; Tsumura, M.; Uesaka, T.; Yako, K.; Yanagisawa, Y.; Yokoyama, R.; Yoshida, K.

    2016-02-01

    A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained in the double-charge-exchange reaction 4He (8H3, 8Be) at 186 MeV /u . The energy of the state is 0.83 ±0.65 (stat ) ±1.25 (syst ) MeV above the threshold of four-neutron decay with a significance level of 4.9 σ . Utilizing the large positive Q value of the (8He, 8Be) reaction, an almost recoilless condition of the four-neutron system was achieved so as to obtain a weakly interacting four-neutron system efficiently.

  7. Inclusive proton polarization in. gamma. sup 3,4 He r arrow pX reactions

    SciTech Connect

    Zybalov, A.A.; Karasev, S.P.; Konovalov, O.G.; Marekhin, S.V.; Sorokin, P.V.; Storozhenko, Y.O.; Tenishev, A.E. )

    1989-05-01

    This paper presents the first measured data on the inclusive proton polarization in the interaction of photons with {sup 3}He and {sup 4}He nuclei. The proton energy (170 MeV) and emission angle (72{degree}) were chosen such that the proton yield from the meson photoproduction reaction on free nucleons should be kinematically forbidden, and the photon energy in the disintegration of the two-nucleon pair in the nucleus should be such that ensures an essential polarization of the proton from the deuteron photodisintegration. The measurements were performed using the Kharkov 2 GeV electron linac facilities. (AIP)

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  10. 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.

  11. Self-consistent continuum random-phase approximation calculations of {sup 4}He electromagnetic responses

    SciTech Connect

    De Donno, V.; Co', G.; Anguiano, M.; Lallena, A. M.

    2011-09-15

    We study the electromagnetic responses of {sup 4}He within the framework of the self-consistent continuum random-phase approximation theory. In this approach, the ground-state properties are described by a Hartree-Fock calculation. The single-particle basis constructed in this manner is used in the calculations of the continuum responses of the system. Finite-range interactions are considered in the calculations. We compare our results with photon-absorption cross sections and electron-scattering quasielastic data. From this comparison, and also from the comparison with the results of microscopic calculations, we deduce that our approach describes well the continuum excitation.

  12. 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.

  13. 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.

  14. Observations of Vortex Emissions from Superfluid 4He Turbulence at High Temperatures

    NASA Astrophysics Data System (ADS)

    Oda, S.; Wakasa, Y.; Kubo, H.; Obara, K.; Yano, H.; Ishikawa, O.; Hata, T.

    2014-04-01

    An immersed object with high velocity oscillations causes quantum turbulence in superfluid 4He, even at very low temperatures. The continuously generated turbulence may emit vortex rings from a turbulent region. In the present work, we report vortex emissions from quantum turbulence in superfluid 4He at high temperatures, by using three vibrating wires as a turbulence generator and vortex detectors. Two detector wires were mounted beside a generator wire: one in parallel and the other in perpendicular to the oscillation direction of the generator. The detection times of vortex rings represent an exponential distribution with a delay time t 0 and a mean detection period t 1. The delay time includes the generation time of a fully developed turbulence and the time-of-flight of a vortex ring. At high temperatures, vortices are dissipated by relative motion between a normal fluid component and the vortices, resulting that only large vortex rings are reachable to the detectors. Using this method, we detected vortex rings with a diameter of 100 μm, comparable to a peak-to-peak vibration amplitude of 104 μm of the generator. The large vortices observed here are emitted anisotropically from the generator. The emissions parallel to the vibrating direction are much less than those perpendicular to the direction.

  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. 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.

  17. Unusual behavior of 3He-4He mixtures in connected OD boxes

    NASA Astrophysics Data System (ADS)

    Kimball, M. O.; Gasparini, F. M.

    2009-02-01

    We report on measurements of the specific heat of 3He-4He mixtures confined to boxes connected with fill channels 1 μm wide and 19 nm high. These data were meant as a study of mixtures to test universality of finite-size scaling along the lambda-line. We find instead that the mixtures have very unusual behavior relative to mixtures studied in geometries for 2D and 1D crossover. These latter data can be scaled successfully as long as one does not include data for pure 4He. In contrast, the 0D crossover data do not scale on either side of the bulk transition temperature Tλ and have rather different overall behavior: They show a dramatically larger temperature shift of the specific heat maximum Cmax relative to data for 2D and ID, the value of the specific heat at Tλ is substantially smaller than that observed for the other dimensionalities, and the value of Cmax exceeds the magnitude of the bulk specific heat at the same temperature. This overall behavior is so unusual that it suggests there is a role being played by the connecting channels even though the liquid within them remains in the normal state over the temperature range in which the specific heat is measured.

  18. Pion absorption on {sup 3}He and {sup 4}He with emission of three energetic protons

    SciTech Connect

    LADS Collaboration

    1997-06-01

    Results from a 4{pi} solid angle measurement of the reactions {sup 3}He({pi}{sup +},ppp) and {sup 4}He({pi}{sup +},ppp)n at incident pion energies of T{sub {pi}{sup +}}=70, 118, 162, 239, and 330 MeV are presented. For {sup 3}He the total absorption cross sections and their decomposition into two-proton and three-proton components are evaluated; for {sup 4}He the three-proton absorption cross sections are given. The differential distributions of the three-proton multinucleon absorption mode of both nuclei are analyzed and compared to each other by making use of a complete set of variables. The data are investigated for signatures of initial and final state interactions: it is found that more than half of the three-proton yield cannot be accounted for by cascade mechanisms. The remaining strength shows dependence on the incident pion angular momentum, but also structures that are not explained by simple semiclassical models. {copyright} {ital 1997} {ital The American Physical Society}

  19. Study on the Turbulent Flow of Superfluid 4He Generated by a Vibrating Wire

    SciTech Connect

    Yano, H.; Handa, A.; Obara, K.; Ishikawa, O.; Hata, T.; Nakagawa, M.

    2006-09-07

    We have studied the flow of superfluid 4He generated by a vibrating wire. As the drive force increases, the velocity of the wire grows in the laminar-flow regime, until it suddenly drops at the onset of the turbulent-flow regime. As the drive force decreases, the turbulence disappears at a critical velocity. This result suggests that the vortices on the wire are confined within a finite size, even in turbulence. We have measured the critical velocity of seven vibrating wires, whose resonance frequencies range from 0.5 kHz to 9 kHz, at 1.4 K and found that the critical velocity is almost constant below an oscillation frequency of 2 kHz and increases above this frequency. We have also observed the response of a vibrating wire in superfluid 4He at a low temperature of 30 mK. We find that the resonance frequency jumps upward at the same moment as the entry of the flow to a turbulent state. The frequency jump may be caused by vortex dynamics such as expansion, entanglement, and reconnection occurring in the turbulence.

  20. 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.

  1. 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.}

  2. 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

  3. 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.

  4. 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

  5. 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)].

  6. 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.

  7. 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

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

    NASA Astrophysics Data System (ADS)

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

    1999-09-01

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

  9. 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.}

  10. 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.

  11. Development of Experiments to Measure D and 4He Charge Radii with Elastic Electron Scattering Method

    NASA Astrophysics Data System (ADS)

    Saudi, Sheikh

    Charge radii are one of the important physical characteristics to understand the electromagnetic structure of nuclei. For light nuclei, they are playing a more critical role to better understand the nucleon-nucleon interaction and test the existing models for bound states. Recent measurements of proton radius, done with muonic hydrogen spectroscopy, showed about 7 standard deviation lower than previous experimental results. This discrepancy triggered the so called "Proton Radius Puzzle" in physics world. Several groups are preparing to perform new experiments to extract the proton radius with better precision and model independent methods. It is equally important to perform new experiments for light nuclei, like deuteron (D) and helium-4 (4He), to verify the existing results for their radii. In this thesis work, we have developed an experimental method based on coincidence detection of the scattered electrons and recoiled light nuclei to measure the charge radii of deuteron and helium-4 with high accuracy.

  12. {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.

  13. 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

  14. Predictive theory for elastic scattering and recoil of protons from 4He

    NASA Astrophysics Data System (ADS)

    Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr

    2014-12-01

    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 Schrödinger 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 of either hydrogen or helium. 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.

  15. A Continuous 4He Refrigerator for Use in a Superfluid Helium Bath

    SciTech Connect

    Wang, Suwen; Avaloff, D.; Nissen, J. A.; Stricker, D. A.; Lipa, J. A.

    2006-09-07

    In cryogenic applications in space, the base temperature, Tmin of the helium bath in the dewar is typically determined by the design of the porous plug and the associated plumbing. For certain experiments, the required operating temperature of the instrument is lower than the bath temperature. In the laboratory, temperatures below 1.2 K require very large pumps or the use of 3He systems. We have demonstrated a modified 4He refrigerator with a continuous fill from a superfluid helium bath with a base temperature more than 0.5 K below the bath temperature. We describe the operation as well as the mechanism of such a refrigerator. For operation in space the refrigerator would need to be equipped with a porous plug to retain the fluid.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Selective-adsorption line shapes in the scattering of 4He by LiF(001)

    NASA Astrophysics Data System (ADS)

    Wesner, David A.; Frankl, Daniel R.

    1981-08-01

    Selective-adsorption line shapes were experimentally studied in 17-meV 4He-atom scattering from a LiF(001) crystalline surface. The specular and several diffracted beams were measured for a variety of incidence conditions. Specular line shapes obey the three rules put forth by Wolfe and Weare. The specular and diffracted-beam line shapes obey the rules formulated recently by Celli, Garcia, and Hutchison in all cases except for the specular Wolfe-Weare rule-2 case. In this case the mixed-extrema structure predicted by Wolfe and Weare is seen. This line shape is very sensitive to surface temperature and age, confirming a recent prediction of Wolfe and Weare concerning inelastic effects on the selective-adsorption line shapes.

  2. 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.

  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. PMID:16339442

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Probing Liquid ^4 He 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.

    2016-06-01

    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 ^4 He 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 ^4 He. The multifrequency technique could also be used for studies of the onset of non-linear phenomena such as quantum turbulence and cavitation in superfluids.

  10. Transport in ultradilute solutions of 3He in superfluid 4He

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    We calculate the effect of a heat current on transporting 3He dissolved in superfluid 4He at ultralow concentration, as will be utilized in a proposed experimental search for the electric dipole moment of the neutron (nEDM). In this experiment, a phonon wind will be generated to drive (partly depolarized) 3He down a long pipe. In the regime of 3He concentrations ≲10-9 and temperatures ˜0.5 K, the phonons comprising the heat current are kept in a flowing local equilibrium by small angle phonon-phonon scattering, while they transfer momentum to the walls via the 4He first viscosity. On the other hand, the phonon wind drives the 3He out of local equilibrium via phonon-3He scattering. For temperatures below 0.5 K, both the phonon and 3He mean free paths can reach the centimeter scale, and we calculate the effects on the transport coefficients. We derive the relevant transport coefficients, the phonon thermal conductivity, and the 3He diffusion constants from the Boltzmann equation. We calculate the effect of scattering from the walls of the pipe and show that it may be characterized by the average distance from points inside the pipe to the walls. The temporal evolution of the spatial distribution of the 3He atoms is determined by the time dependent 3He diffusion equation, which describes the competition between advection by the phonon wind and 3He diffusion. As a consequence of the thermal diffusivity being small compared with the 3He diffusivity, the scale height of the final 3He distribution is much smaller than that of the temperature gradient. We present exact solutions of the time dependent temperature and 3He distributions in terms of a complete set of normal modes.

  11. 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.

  12. Third Sound in Superfluid 4He Films Adsorbed on Packed Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Menachekanian, Emin

    Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the 4th and 5th atomic layers. Sharp changes in the Q factor of the third sound are found at partial layer fillings. Temperature sweeps at a number of fill points show strong broadening effects on the Kosterlitz-Thouless (KT) transition, and rapidly increasing dissipation, in qualitative agreement with the predictions of Machta and Guyer. At the 4th layer completion there is a sudden reduction of the transition temperature TKT , and then a recovery back to linear variation with fill, although the slope is considerably smaller than the KT prediction. These effects might be related to changes in the gas-liquid coexistence regions.

  13. Photon scattering from 12C and 4He nuclei near the Δ(1232) resonance

    NASA Astrophysics Data System (ADS)

    Igarashi, R.; Bergstrom, J. C.; Caplan, H. S.; Doss, K. G. E.; Hallin, E. L.; Skopik, D. M.; Delli Carpini, D.; Booth, E. C.; McIntyre, E. K.; Miller, J. P.; Lucas, M. A.; MacGibbon, B. E.; Nathan, A. M.; Wells, D.

    1995-08-01

    Angular distributions for photon scattering from 12C and 4He have been measured using continuous wave bremsstrahlung from the Saskatchewan Accelerator Laboratory pulse stretcher ring. Data for carbon were taken at 158.8, 195.2, 197.2, 247.2, and 290.2 MeV end-point energies, and for helium were taken at an end-point energy of 158.8 MeV. A large NaI(Tl) gamma ray spectrometer with 1.7% resolution was used to detect the scattered photons at laboratory scattering angles ranging from 20° to 150°. The excellent energy resolution of the NaI detector allowed a separation of elastic from inelastic photon scattering for the first time at these energies. The angular distributions for elastic scattering are in only fair agreement with delta-hole theory and theory based on the optical theorem at forward angles, and completely disagree with theory at backward angles. Measured cross sections for inelastic scattering leading to the 4.43 MeV state in carbon are small compared to the elastic scattering at forward angles, but are dominant at backward angles. This experiment is the first to separate elastic from inelastic photon scattering at these energies.

  14. Time-of-Flight Measurements of Vortices Emitted from Quantum Turbulence in Superfluid 4He

    NASA Astrophysics Data System (ADS)

    Kubo, H.; Nago, Y.; Nishijima, A.; Obara, K.; Yano, H.; Ishikawa, O.; Hata, T.

    2013-06-01

    An oscillating obstacle generates quantum turbulence in superfluids, when vortices remained attached to obstacle surfaces or vortex rings collided with it during oscillation. Turbulence provides a source of vortices; however, the characteristics of these vortices are not clear. In the present work, we report the flight of vortices emitted from quantum turbulence in superfluid 4He at low temperatures, using vibrating wires as a generator and a detector of vortices. A vortex-free vibrating wire can detect only the first colliding vortex ring, though it will be refreshed after low vibration and be able to detect a vortex ring again. By measuring a period from the start of turbulence generation to the vortex detection repeatedly, we find an exponential distribution of time-of-flights with a non-detection period t 0 and a mean detection period t 1, suggesting a Poisson process. Both periods t 0 and t 1 increase with increasing distance between a generator and a detector. A vortex flight velocity estimated from period t 0 suggests that the sizes of the emitted vortex rings distribute to a range smaller than a generator thickness or a generator vibration amplitude. Vortices are emitted radially from a turbulence region, at least in the direction of oscillator vibration.

  15. Generation and detection of vortex rings in superfluid 4He at very low temperature

    NASA Astrophysics Data System (ADS)

    Yano, H.; Nishijima, A.; Yamamoto, S.; Ogawa, T.; Nago, Y.; Obara, K.; Ishikawa, O.; Tsubota, M.; Hata, T.

    2012-12-01

    Motions of vortices are fundamental characteristics of quantum turbulence. These motions are expected to be governed only by quantized circulations in superfluids at the zero temperature limit. In the present paper, we report the motions of vortex rings emitted from a quantum turbulence in superfluid 4He, by detecting vortex rings using a vortex-free vibrating wire as a detector. The time of flights of vortex rings are distributed, because vortex rings are emitted in any direction from a turbulent region and the detector can respond only to a reachable vortex ring. By measuring time-of-flights many times, we find an exponential distribution of time-of-flights with a non-detection period, which corresponds to the fastest time of flights of vortex rings. For a larger generation power of vortex rings, a distribution of time-of-flights still shows a single exponential distribution, but a non-detection period becomes shorter. This result implies that sizes of emitted vortex rings are distributed dependently on the generation power of turbulence. The observed exponential distributions are confirmed by numerical simulations of the dynamics of vortex rings.

  16. 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.

  17. Development of low temperature solid state detectors for ultra-cold neutrons within superfluid 4He

    NASA Astrophysics Data System (ADS)

    Baker, C. A.; Balashov, S. N.; Green, K.; van der Grinten, M. G. D.; Iaydjiev, P. S.; Ivanov, S. N.; Pendlebury, J. M.; Shiers, D. B.; Tucker, M. A. H.; Yoshiki, H.; Geltenbort, P.

    2003-04-01

    As part of an R&D programme for the development of a next-generation experiment to measure the neutron electric dipole moment, in which ultra-cold neutrons (UCN) are produced and stored in superfluid 4He (superthermal source), we have developed cryogenic detectors of UCN that can operate in situ within the superfluid. Surface barrier detectors and PIN diode detectors have been tested and proven to work well at temperatures as low as 80 mK. When combined with a layer of 6LiF which converts neutrons to charged particles, these detectors form a reliable UCN detection system which has been tested in liquid helium down to 430 mK. The detectors have operated within superfluid helium for periods of up to 30 days with no signs of degradation. The development of this detection system has enabled us to measure the flux of UCN from a superthermal UCN source with no intervening transmission windows which can attenuate the flux. The addition of thin films of magnetically aligned iron also enables these detectors to be used in situ for neutron spin-polarisation analysis.

  18. 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

  19. 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

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

    NASA Astrophysics Data System (ADS)

    Schuster, Micah; Quaglioni, Sofia; Johnson, Calvin; Jurgenson, Eric; Navratil, Petr

    2015-04-01

    A goal of nuclear theory is to make quantitative predictions of low-energy nuclear observables starting from accurate microscopicinternucleon forces. Modern effective interaction theory, 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, is a major element of such an effort. The consistent simultaneous transformation of external operators, however, has been overlooked in applications of the theory, particularly for non-scalar 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 calculation of the 4 He total photo absorption cross section and electric dipole polarizability. All observables are calculated within the ab initio no-core shell model. We find that, although seemingly small, the effects of induced operators on the photo absorption cross section are comparable in magnitude to the correction produced by including the three-nucleon force and cannot be neglected. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  1. Human epididymis protein 4 (HE4) in laboratory medicine and an algorithm in renal disorders.

    PubMed

    Kappelmayer, János; Antal-Szalmás, Péter; Nagy, Béla

    2015-01-01

    Over the past three decades, cancer antigen (CA) 125 has been utilized for monitoring women who were treated for ovarian cancer. However, this tumor marker showed several limitations such as false elevation in benign pelvic diseases and, in turn, no alterations in ovarian tumors at early stages with a relatively high ratio. For more than ten years, the human epididymis protein 4 (HE4) has become available for the routine laboratory repertoire, showing a higher sensitivity and specificity compared to that of CA125 in ovarian malignancies, but also in other types of tumors based on recently accumulated clinical data. Despite its remarkable diagnostic characteristics, in certain cases, the evaluation of HE4 results may be problematic when patients suffer from additional conditions that may alter HE4 level. Besides the direct effects of age and smoking, menopause status and decreased renal function also show a substantial impact on HE4 values, which should be considered in each patient. For this purpose, we attempted to create a new formula and an algorithm that may be helpful to predict the probability of the presence of ovarian tumor by using the concentrations of HE4 and CA125. PMID:25127713

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Investigation of Grid Turbulence in Superfluid 4He with Improved Measurement Technique

    NASA Astrophysics Data System (ADS)

    Yang, Jihee; Ihas, Gary G.

    Quantum turbulence(QT), a tangle of quantized vorticity in a macroscopically correlated quantum fluid, can have many analogous aspects to classical turbulence. Understanding QT can give us insights into classical turbulence as well as fluids in general. We generate QT by pulling a grid through a 4.6 cm x 4.6 cm cross-section channel in superfluid 4He. Second sound, a temperature/entropy wave, is used to monitor vorticity, ω. A resonant technique with high (3000) Q increases greatly the sensitivity of the measurement, but it requires a phase and amplitude locked tracking system which adheres to the resonant peak independent of frequency shifts. According to theories, the vorticity decays as ω ~ t- 11 / 10 or ω ~ t- 17 / 14 when the energy containing eddies are growing. When they saturate at the channel size, the vorticity begins decaying as ω ~ t3/2. These different decaying regions are examined in this large channel and compared to previous experiments that have been performed in 1 cm2 square channels. US NSF DMR#1007937.

  8. Theory of deep inelastic neutron scattering. II. Application to normal and superfluid 4He

    NASA Astrophysics Data System (ADS)

    Silver, Richard N.

    1989-03-01

    The hard-core perturbation theory (HCPT) predictions for high-momentum-transfer neutron scattering from liquid 4He are numerically evaluated. The input to the calculations are Monte Carlo and variational momentum distributions, the radial distribution function, and the Jeffreys-Wentzel-Kramers-Brillouin phase shifts for the He potential. Consistent with the ω2 sum rule, the Gaussian width of the dynamic structure function S(Q,ω) is the same in HCPT and in the impulse approximation (IA). However, where the IA predicts structure in S(Q,ω) below Tλ due to the Bose condensate, HCPT predicts that S(Q,ω) is smoothed by final-state broadening. The final-state effects are negligible for the normal fluid above Tλ. The approach to the IA at high Q is shown to be O(logQ) for the He-He potential, which implies that S(Q,ω) satisfies approximate Y scaling and that final-state broadening is significant for all feasible experiments. Extensions of HCPT to lower Q and to other systems are qualitatively discussed. The problem of extracting momentum distributions in quantum fluids and solids from high-Q neutron scattering is addressed.

  9. Theory of deep inelastic neutron scattering. II. Application to normal and superfluid /sup 4/He

    SciTech Connect

    Silver, R.N.

    1989-03-01

    The hard-core perturbation theory (HCPT) predictions for high-momentum-transfer neutron scattering from liquid /sup 4/He are numerically evaluated. The input to the calculations are Monte Carlo and variational momentum distributions, the radial distribution function, and the Jeffreys-Wentzel-Kramers-Brillouin phase shifts for the He potential. Consistent with the ..omega../sup 2/ sum rule, the Gaussian width of the dynamic structure function S(Q,..omega..) is the same in HCPT and in the impulse approximation (IA). However, where the IA predicts structure in S(Q,..omega..) below T/sub lambda/ due to the Bose condensate, HCPT predicts that S(Q,..omega..) is smoothed by final-state broadening. The final-state effects are negligible for the normal fluid above T/sub lambda/. The approach to the IA at high Q is shown to be O(logQ) for the He-He potential, which implies that S(Q,..omega..) satisfies approximate Y scaling and that final-state broadening is significant for all feasible experiments. Extensions of HCPT to lower Q and to other systems are qualitatively discussed. The problem of extracting momentum distributions in quantum fluids and solids from high-Q neutron scattering is addressed.

  10. One-Dimensional Liquid 4He: Dynamical Properties beyond Luttinger-Liquid Theory

    NASA Astrophysics Data System (ADS)

    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 4He 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.

  11. The reflection of low energy phonons at the free surface of liquid4He. II. Experiment

    NASA Astrophysics Data System (ADS)

    Baddar, H.; Edwards, D. O.

    1996-09-01

    Using a heater and bolometer as source and detector, the reflection of a pulsed beam of phonons at the free surface of liquid4He at ˜ 0.05 K has been measured for angles of incidence between 30 ° and 80 °. The energy distribution of the incident beam was obtained from the theory of phonon decay in the accompanying paper (I). The average incident phonon energy was ˜ 0.3 K, corresponding to an effective beam temperature of about 0.1 K. Both heater and bolometer were made from graphite resistor board with a layer of poly aniline fibers to increase the absorptivity for rotons. The angular distribution of the phonons from the heater is quite broad, approximately (cosn π+cosm θ)/2 with n ≈ 0.65 and m ≈ 3.4. However, the receiver response has a broad component with n ≈ 2.2 and an extraordinarily narrow one with m ≈ 106. In agreement with the theory in I, the reflection appears to be specular within the accuracy of the experiment. The reflection coefficient is unity within the experimental error; the weighted mean value is 1.001±0.025. During the experiment, the free surface became contaminated with ˜ 0.034 of a monolayer of3He, but no effect from the3He impurity was observed.

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

    NASA Astrophysics Data System (ADS)

    Perisanu, Sorin; Vermeulen, Gerard

    2007-08-01

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

  13. First-principles modeling of quantum nuclear effects and atomic interactions in solid 4He at high pressure

    NASA Astrophysics Data System (ADS)

    Cazorla, Claudio; Boronat, Jordi

    2015-01-01

    We present a first-principles computational study of solid 4He at T =0 K and pressures up to ˜160 GPa. Our computational strategy consists in using van der Waals density functional theory (DFT-vdW) to describe the electronic degrees of freedom in this material, and the diffusion Monte Carlo (DMC) method to solve the Schrödinger equation describing the behavior of the quantum nuclei. For this, we construct an analytical interaction function based on the pairwise Aziz potential that closely matches the volume variation of the cohesive energy calculated with DFT-vdW in dense helium. Interestingly, we find that the kinetic energy of solid 4He does not increase appreciably with compression for P ≥85 GPa. Also, we show that the Lindemann ratio in dense solid 4He amounts to 0.10 almost independently of pressure. The reliability of customary quasiharmonic DFT (QH DFT) approaches in describing quantum nuclear effects in solids is also studied. We find that QH DFT simulations, although provide a reasonable equation of state in agreement with experiments, are not able to reproduce correctly these critical effects in compressed 4He. In particular, we disclose huge discrepancies of at least ˜50 % in the calculated 4He kinetic energies using both the QH DFT and present DFT-DMC methods.

  14. 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.

  15. Search of Superfluidity of Solid 4He in a Porous Vycor Glass by Means of the Ultrasound Technique

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Fukazawa, S.; Taniguchi, J.; Suzuki, M.; Shirahama, K.

    2006-09-01

    Kim and Chan have reported that solid 4He shows a reduction of the rotational moment of inertia below 0.2 K, which suggests an onset of superfluidity. Ultrasound should be sensitive to mass decoupling caused by superfluidity. If a superfluid component exists, the sound velocity of a porous material filled with solid 4He could increase. We have carried out ultrasonic measurements for a porous Vycor glass filled with solid 4He. Since the reported "critical velocity" is very low, we have adopted a continuous wave resonance technique which realizes the oscillating velocity less than 1 × 10-7 m/s. The resolution of the sound velocity is 10-5 for small oscillating velocities, and is enough to detect the expected mass decoupling. Although the present experimental conditions are rather limited, no signature of supersolid has been observed.

  16. Measurements of the strong-interaction widths of the kaonic 3He and 4He 2p levels

    NASA Astrophysics Data System (ADS)

    SIDDHARTA Collaboration; Bazzi, M.; Beer, G.; Bombelli, L.; Bragadireanu, A. M.; Cargnelli, M.; Curceanu (Petrascu), C.; d'Uffizi, A.; Fiorini, C.; Frizzi, T.; Ghio, F.; Guaraldo, C.; Hayano, R. S.; Iliescu, M.; Ishiwatari, T.; Iwasaki, M.; Kienle, P.; Levi Sandri, P.; Longoni, A.; Marton, J.; Okada, S.; Pietreanu, D.; Ponta, T.; Rizzo, A.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Tudorache, A.; Tudorache, V.; Vazquez Doce, O.; Wünschek, B.; Widmann, E.; Zmeskal, J.

    2012-07-01

    The kaonic 3He and 4He X-rays emitted in the 3d→2p transitions were measured in the SIDDHARTA experiment. The widths of the kaonic 3He and 4He 2p states were determined to be Γ2p(He3)=6±6(stat.)±7 (syst.) eV, and Γ2p(He4)=14±8 (stat.)±5 (syst.) eV, respectively. Both results are consistent with the theoretical predictions. The width of kaonic 4He is much smaller than the value of 55±34 eV determined by the experiments performed in the 70's and 80's, while the width of kaonic 3He was determined for the first time.

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

    NASA Astrophysics Data System (ADS)

    Vekhov, Ye.; Hallock, R. B.

    2016-03-01

    The DC superfluid ^4 He mass flux through a cell filled with solid ^4 He diluted by ppm amounts of ^3 He 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.

  18. Mass Flux Stability at the T_d Conductance Transition in Solid ^3He-^4He Mixtures

    NASA Astrophysics Data System (ADS)

    Vekhov, Yegor; Hallock, R. B.

    2016-05-01

    Measurements of the ^4He mass flux through a cell filled with solid ^3He-^4He mixtures in the ^3He concentration range 0.17-220 ppm have demonstrated a reversible dramatic decrease in the flux on cooling through a concentration-dependent temperature T_d, close to the mixture phase separation temperature. For low ^3He concentrations, the flux change transition is complete within 2 mK. We report on the stability of the flux for fixed temperatures in this transition region.

  19. Kaonic 3He and 4He measurements in the SIDDHARTA experiment at the DAΦNE collider

    NASA Astrophysics Data System (ADS)

    Tatsuno, H.; Bazzi, M.; Beer, G.; Bombelli, L.; Bragadireanu, A. M.; Cargnelli, M.; Curceanu (Petrascu), C.; d'Uffizi, A.; Fiorini, C.; Frizzi, T.; Ghio, F.; Guaraldo, C.; Hayano, R. S.; Iliescu, M.; Ishiwatari, T.; Iwasaki, M.; Kienle, P.; Levi Sandri, P.; Longoni, A.; Marton, J.; Okada, S.; Pietreanu, D.; Ponta, T.; Rizzo, A.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tudorache, A.; Tudorache, V.; Vazquez Doce, O.; Widmann, E.; Wünschek, B.; Zmeskal, J.

    2012-12-01

    The SIDDHARTA collaboration measured kaonic 3He and 4He 3d → 2p X-rays with gaseous targets at the DAΦNE e+e- collider. The 2p-state strong-interaction shifts and widths were precisely determined by using 144 high-resolution silicon drift detectors. The shift of K-4He is in good agreement with theoretical calculations and consistent with the recent experimental result of KEK-PS E570. The shift of K-3He is also determined for the first time. The newly determined widths are in agreement with optical model calculations.

  20. 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.

  1. 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.

  2. Multinucleon pion absorption on {sup 4}He into the pppn final state

    SciTech Connect

    Lehmann, A.; Backenstoss, G.; Koehler, J.; Kroedel, M.; Weyer, H.J.; Wildi, M.; Hoffart, A.; Trezeciak, R.; Ullrich, H.; Gram, P.A.; Breuer, H.; Gregory, N.K.; Mateos, A.O.; Redwine, R.P.; Rowntree, D.; Simicevic, N.; Wilson, K.E.; Kyle, G.; Wang, M.; Wang, M.H.; Dooling, T.; Klein, A.; Lehmann, A.; Doebbeling, H.; Hoffart, A.; Ingram, C.H.; Koch, K.; Kotlinski, B.; Michaelian, K.; Sennhauser, U.; Weyer, H.J.; Androic, D.; Bosnar, D.; Furic, M.; Petkovic, T.; Planinic, M.

    1997-10-01

    Results from a 4{pi} solid angle measurement of the reaction {pi}{sup +4}He{r_arrow}pppn at incident pion energies of T{sub {pi}{sup +}}= 70, 118, 162, 239, and 330 MeV are presented. Integrated cross sections are given for the reactions where three nucleons participate, leading to energetic (ppp) or (ppn) final states, and for states where four nucleons are involved (pppn). The two three-nucleon absorption modes were investigated in particular, and an energy dependent isospin ratio of the cross sections of {sigma}{sub ppn}/ {sigma}{sub ppp}=3.6{plus_minus}1.3, 2.6 {plus_minus}0.5, 1.8{plus_minus}0.3, 1.4{plus_minus} 0.2, and 1.8{plus_minus}0.6 was determined from 70 to 330 MeV. The differential cross sections were described by a complete set of eight independent variables and compared to simple cascade and phase space models. From this analysis the contributions from initial state interactions to the multinucleon absorption cross sections were found to be more important at higher pion energies, while those from final state interactions are stronger at lower energies. However, both mechanisms combined were found to account for not more than one-third of the total pppn multinucleon yield. The remaining strength is reasonably well reproduced by phase space models, but shows a dependence on the incident pion{close_quote}s orbital angular momentum. The isospin structure of the (ppp) and (ppn) final states is not understood, nor are some structures in their distributions. The four-nucleon yield (pppn) was found to be weak (1{endash}8{percent} of the total absorption cross section) and shows no evidence for a {open_quotes}double- {Delta}{close_quotes} excitation. {copyright} {ital 1997} {ital The American Physical Society}

  3. 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 *}.

  4. Prediction of stable C7 /12 and metastable C4 /7 commensurate solid phases for 4He on graphite

    NASA Astrophysics Data System (ADS)

    Ahn, Jeonghwan; Lee, Hoonkyung; Kwon, Yongkyung

    2016-02-01

    Using a substrate potential described by a pairwise sum of empirical 4He-C interatomic potentials, we have performed path-integral Monte Carlo calculations for 4He adatoms on graphite. It is found that a second-layer commensurate structure is not stable above an incommensurate first-layer triangular solid. This is consistent with the conclusion of the previous theoretical study of Corboz et al. [Phys. Rev. B 78, 245414 (2008), 10.1103/PhysRevB.78.245414] that was based on a laterally averaged one-dimensional potential. On the other hand, we observe a new stable C7 /12 commensurate solid in the first 4He layer at the areal density of 0.111 Å-2, which is close to the second-layer promotion density. This high-density commensurate solid exhibits a √{12 }×√{12 } structure registered to the graphite surface that is not disrupted by the development of the second 4He layer. Furthermore, a second-layer 4/7 commensurate structure relative to the first-layer C7 /12 solid is found to be at least metastable, opening the possibility of two-dimensional supersolidity.

  5. Correlated wave functions and hyperfine splittings of the 2 s state of muonic sup 3,4 He atoms

    SciTech Connect

    Chen, M. )

    1992-02-01

    The correlated wave functions of the 2{ital s} state, (1{ital s}){sub {ital e}}(2{ital s}){sub {mu}} of muonic {sup 4}He and {sup 3}He atoms are calculated by the variational approach, employing an improved set of the Hylleraas-type basis functions to study the 2{ital s} state of muonic He atoms. The energy and radial expectation values are calculated. Our proposed wave functions for the muonic {sup 4}He and {sup 3}He atoms are good enough to describe the electron and muon at small, intermediate, and large values of radial coordinates. The hyperfine splittings of the (1{ital s}){sub {ital e}}(2{ital s}){sub {mu}} muonic {sup 4}He and {sup 3}He atoms are also presented. Including relativistic, QED, and other corrections up to {ital O}({alpha}{sup 2}), we arrive at the values {Delta}{nu}= 4287.01{plus minus}0.10 and 4052.64{plus minus}0.10 MHz for the total hyperfine splittings of the 2{ital s} state of muonic {sup 4}He and {sup 3}He atoms, respectively.

  6. L-series X-ray yields of kaonic 3He and 4He atoms in gaseous targets

    NASA Astrophysics Data System (ADS)

    Bazzi, M.; Beer, G.; Berucci, C.; Bragadireanu, A. M.; Cargnelli, M.; Curceanu, C.; d'Uffizi, A.; Fiorini, C.; Ghio, F.; Guaraldo, C.; Hayano, R. S.; Iliescu, M.; Ishiwatari, T.; Iwasaki, M.; Sandri, P. Levi; Marton, J.; Okada, S.; Pietreanu, D.; Ponta, T.; Quaglia, R.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Vazquez Doce, O.; Wünschek, B.; Widmann, E.; Zmeskal, J.

    2014-05-01

    The SIDDHARTA experiment measured X-rays from kaonic helium atoms using, for the first time, gaseous 3He and 4He targets. Clear patterns of the L-series X-rays of kaonic 3He and 4He atoms were observed. By using accurate Monte Carlo simulations, the absolute yields of these X-ray transitions were determined to be Y(3 d → 2 p) = 25.0{-5.8/+6.7}% for 3He (0.96 g/l), Y(3 d → 2 p) = 23.1{-4.2/+6.0}% for 4He (1.65 g/l), and Y(3 d → 2 p) = 17.2{-9.5/+2.6}% for 4He (2.15g/l). In addition, the yields Y ( nd → 2 p), with n > 3 were also determined. The measured yields provide valuable information for understanding the cascade processes of kaonic helium atoms as a function of the target density.

  7. Near-threshold search for the isospin-forbidden d+darrow^4He+π^0 reaction.

    NASA Astrophysics Data System (ADS)

    Stephenson, E. J.; Allgower, C.; Bacher, A. D.; Doskow, J.; Lavelle, C.; Nann, H.; Olmsted, J.; Rinckel, T.; Pickar, M. A.; Pancella, P. V.; Smith, A.; Spinka, H. M.; Rapaport, J.

    2002-10-01

    We will discuss our search at 228.5 MeV for the isospin-forbidden ddarrow^4Heπ^0 reaction, which constrains charge symmetry breaking contributions from the down-up quark mass difference and electromagnetic effects. The forward-going ^4He nuclei, which lie inside a θ_lab=1.2^rc cone, are separated from the deuteron beam in a 6^rc bending magnet and captured and identified in a magnetic channel. Separation of ^4Heπ^0 events depends on a reconstruction of the pion missing mass from channel position and time of flight in order to distinquish them from double radiative capture ^4Heγγ events. Two detector systems observe d+d elastic scattering at θ_c.m.=9.1^rc and 90^rc as a monitor of the luminosity ( ˜ 2× 10^31 /cm^2/s) given by the circulating IUCF Cooler beam and a cold D2 jet target. The d+d cross sections are scaled from p+d elastic cross sections by observing both during a run with a molecular HD target. Following two d+d commissioning runs, production began in early June 2002 and is planned to continue in July.

  8. Energy spectra of single neutrons and charged particles emitted following the absorption of stopped negative pions in 4He

    NASA Astrophysics Data System (ADS)

    Cernigoi, C.; Gabrielli, I.; Grion, N.; Pauli, G.; Saitta, B.; Ricci, R. A.; Boccaccio, P.; Viesti, G.

    1981-02-01

    Energy spectra have been measured of single neutrons, protons and deuterons emitted following the capture at rest of negative pions in 4He. The neutron energy spectrum has been measured with an energy resolution of 4% at 90 MeV. The absolute number of stopped pions has been measured.

  9. 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.

  10. 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.