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Sample records for he3 he4 heavy

  1. Energy dependence and temporal evolution of the 3He/4He ratios in heavy-ion-rich energetic particle events

    International Nuclear Information System (INIS)

    Moebius, E.; Hovestadt, D.; Klecker, B.; Gloeckler, G.

    1980-01-01

    The energy dependence of the 3 He/ 4 He ratio between 0.44 and 4.1 MeV per nucleon has been studied for six heavy-ion--rich events observed in 1974 and 1976 using the low-energy dE/dx versus E Ultralow-Energy Particle telescope (ULET) on IMP 8. We find that all selected heavy-ion--rich events are also enriched in 3 He, that the 3 He/ 4 He He ratio decreases with decreasing energies, and that a rapid temporal evolution of the 3 He/ 4 He and the Fe/(H+He) ratios is strongly correlated during one event with the maximum value at the onset. These results are discussed in terms of a model which is based on preferential injection of 3 He and Fe resulting from turbulent ion heating and subsequent Fermi acceleration

  2. Dimerization of 3He in 3He-4He mixture films

    International Nuclear Information System (INIS)

    Bashkin, E.

    1994-01-01

    3 He atoms dissolved in superfluid 4 He may form dimers ( 3 He) 2 in two-dimensional geometries. Dimer formation is studied in films of dilute 3 He- 4 He mixture. After designing a schematic 3 He- 3 He interaction potential, the dimer binding energy is calculated for various substrates. It is shown that 3 He impurity states localized near the substrate give rise to the highest magnitudes of the binding energy. (author). 32 refs., 6 figs.,; 1 tab

  3. Bound states of 3He in 3He-4He mixture films

    International Nuclear Information System (INIS)

    Bashkin, E.; Pavloff, N.; Treiner, J.

    1995-01-01

    3 He atoms dissolved in superfluid 4 He may form dimers ( 3 He) 2 in two-dimensional (2D) geometries. We study dimer formation in films of dilute 3 He- 4 He mixture. After designing a schematic 3 He- 4 He interaction potential we calculate the dimer binding energy for various substrates. It is shown that 3 He impurity states localized near the substrate give rise to the largest magnitudes of the binding energies

  4. Large-space cluster model calculations for the 3He(3He,2p)4He and 3H(3H,2n)4He reactions

    International Nuclear Information System (INIS)

    Csoto, Attila; Langanke, Karlheinz

    1999-01-01

    The 3 He( 3 He, 2p) 4 He and 3 H( 3 H, 2n) 4 He reactions are studied in a microscopic cluster model. We search for resonances in the 3 He+ 3 He and 4 He + p + p channels using methods that treat the two- and three-body resonance asymptotics correctly. Our results show that the existence of a low-energy resonance or virtual state, which could influence the 7 Be and 8 B solar neutrino fluxes, is rather unlikely. Our calculated 3 He( 3 He, 2p) 4 He and 3 H( 3 H, 2n) 4 He cross sections are in a good general agreement with the experimental data

  5. Combined He3 cryostats and He3-He4 dilution refrigerators

    International Nuclear Information System (INIS)

    Kovac, L.; Balla, J.

    1974-07-01

    A modular set of equipment was designed, which consists of a 4 He Dewar vessel with a very low evaporation rate, having a pumped 4 He bath in which either a 3 He cryostat or a dilution refrigerator within removable inserts can be placed. Any of them can be simply and rapidly connected to the versatile Dewar, auxiliary 4 He-, vacuum; and 3 He- 4 He systems. Two such sets have already been completed and can be used at temperatures from 1.5K to 0.05K for thermodynamic and neutron diffraction measurements. The performance of all inserts was stable and reliable, differences between the cryostats and runs were small - nearly all within the accuracy of temperature determination. The construction of a lot of parts is identical, allowing rapid manufacture. Assembling and repairs are simple, all parts are easily accessible. (K.A.)

  6. Study of charge symmetry in 4He by simultaneous 4He(e,e'p)3H and 4He(e,e'n)3He measurements

    International Nuclear Information System (INIS)

    Spahn, M.; Kihm, T.; Knopfle, K.T.; Friedrich, J.; Voegler, N.; Schmitt, C.; Walther, V.H.; Unkelbach, M.; Hofmann, H.M.

    1989-01-01

    We have measured the ( 3 H+p) and ( 3 He+n) breakup of 4 He by 4 He(e,e'c) coincidence experiments at low momentum transfer (q∼0.39 fm -1 ) in the excitation energy region 22≤E x ≤36 MeV. Both channels were studied simultaneously by detecting the charged fragments c=p, 3 H, and 3 He in the same detector system. The measured 4 He(e,e'p) 3 H and 4 He(e,e'n) 3 He angular correlations as well as the deduced total 4 He(e,e'p) 3 H and 4 He(e,e'n) 3 He cross sections are reproduced by microscopic model calculations with a charge-symmetric nuclear Hamiltonian

  7. Superfluid 3He dynamcs in 3He - 4He solutions

    International Nuclear Information System (INIS)

    Mejerovich, A.Eh.

    1984-01-01

    The dynamics of a 3 He- 4 He superfluid solution with two condensates ( 3 He and 4 He) is investigated. Despite the fact that the hydrodynamics of the system is a three-velocity one (two superfluid and one normal velocity), all the thermo- and hydrodynamic functions are determined by the value of only a single linear combination of the velocities. 0n the basis of an analogy between a moving solution and a BCS system with coupling with a non-zero momentum, the dependence of the thermodynamic quantities on the velocities and critical velocities can easily be calculated for both homogeneous and inhomogeneous phases of the solution. In a magnetic field the temperature oscillations (analogue of second sound for a superfluid solution) are accompanied by oscillations of the magnetic moment. The velocity and damping of the spin-temperature waves are determined. The orienting action of a current on the inhomogeneous phases of the solution is discussed. It is shown that the energy and size of the vortexes in a superfluid solution are, due to drag effects, oscillating functions of the effective mass of the 3 He quasirartictes (pressure). At a pressure of the order of 10 atm a first order transition should take place in the vortex line which is accompanied by an abrupt change of the circulations of superfluid velocity of 3 He for a fixed circulation of the 4 He velocity

  8. Direct harvesting of Helium-3 (3He) from heavy water nuclear reactors

    International Nuclear Information System (INIS)

    Bentoumi, G.; Didsbury, R.; Jonkmans, G.; Rodrigo, L.; Sur, B.

    2013-01-01

    The thermal neutron activation of deuterium inside a heavy-water-moderated or -cooled nuclear reactor produces a build-up of tritium in the heavy water. The in situ decay of tritium can, for certain reactor types and operating conditions, produce potentially useable amounts of 3 He, which can be directly extracted via the heavy-water cover gas without first separating, collecting and storing tritium outside the reactor. It is estimated that the amount of 3 He available for recovery from the moderator cover gas of a 700 MWe class Pressurized Heavy Water Reactor (PHWR) ranges from 0.1 to 0.7 m 3 (STP) per annum, varying with the tritium activity buildup in the moderator. The harvesting of 3 He would generate approximately 12.7 m 3 (STP) of 3 He, worth more than $30M at current market rates, over a typical 25-year operating cycle of the PHWR. This paper discusses the production of 3 He in the moderator of a PHWR and its extraction from the 4 He moderator cover gas system using conventional methods. (author)

  9. Attractive well of He--He from 3He--4He differential elastic scattering measurements

    International Nuclear Information System (INIS)

    Burgmans, A.L.J.; Farrar, J.M.; Lee, Y.T.

    1976-01-01

    The elastic differential cross section for 3 He-- 4 He was measured at a relative collision energy of 0.799x10 -14 erg, approximately five times the well depth. The data are fitted to a multiparameter potential form with epsilon/k=10.57 degreeK and r/subm/=2.97 A. Comparisons with recent experimental and theoretical helium potentials are made. No evidence for a significant isotope effect in the 3 He-- 4 He and 4 He-- 4 He interactomic potentials is found in this work

  10. X-ray-induced thinning of 3He and 3He/4He mixture films

    International Nuclear Information System (INIS)

    Penanen, Konstantin; Fukuto, Masafumi; Silvera, Isaac F.; Pershan, Peter

    2000-01-01

    Films of isotopic mixtures of helium have been studied using x-ray specular reflectivity techniques. In contrast with superfluid 4 He films, x-ray exposure causes a reduction in the thickness of 4 He films above the superfluid transition as well as films of pure 3 He and 3 He/ 4 He mixtures. One proposed model that could account for this effect is a charging model, in which thinning is caused by electrostatic pressure of free charges that accumulate on the helium surface. Unfortunately, this model is not fully consistent with all of the experimental observations. A localized heating model, in which indirect heating of the film causes it to thin would explain the data if there were dissipative film flow in the 3 He/ 4 He mixtures at temperatures where the bulk is superfluid. We argue that various published experimental results suggest such an effect. In this model, film thinning data for dilute 3 He/ 4 He films indicates dissipation that is linear in 3 He content of the film over two orders of magnitude

  11. Observation of the Rotational Spectra of 4HeH+, 4HeD+, 3HeH+, and 3HeD+

    International Nuclear Information System (INIS)

    Matsushima, F.; Oka, T.; Takagi, K.

    1997-01-01

    Low J rotational transitions of 4 HeH + , 4 HeD + , 3 HeH + , and 3 HeD + were observed in the 2 endash 5THz region with a high-precision far-infrared spectrometer. Dunham coefficients Y kl and isotopically independent parameters U kl , Δ He kl , and Δ H kl were determined. In particular, Δ parameters with k=0 and l=1,2 were determined with unprecedented accuracy, and provide important information for breakdown of the Born-Oppenheimer approximation. The lowest J=1 left-arrow 0 transition of 4 HeH + observed at 2010.1839(2)GHz will be an important future probe for detecting this species in space. copyright 1997 The American Physical Society

  12. NMR and superfluidity of 3He in 3He-4He solutions

    International Nuclear Information System (INIS)

    Ivanova, K.D.; Mejerovich, A.Eh.

    1986-01-01

    Two possibilities of determining the superfluid transition temperature for 3 He in a 3 He- 4 He solution by the NMR technique are discussed. One of the methods consists in measuring the spin diffusion coefficient in weak magnetic fields at ultralow temperatures, and the other in measuring the ratio of the spin diffusion coefficient to the spin wave absorption coefficient at not very low temperatures. The transition temperature is estimated on the basis of the available experimental data. The effect of the superfluid transition in a system of 3 He quasiparticles on the propagation of transverse spin waves and longitudinal spin-sound oscillations in 3 He- 4 He solutions is studied. It is shown that there is a range of weak magnetic field intensities restricted from both sides in which the propagation of weakly damped spin-sound waves is possible

  13. Superfluidity of a dilute 3He-4He solution

    International Nuclear Information System (INIS)

    Soda, Toshio

    1993-01-01

    The interaction between two 3 He atoms is calculated by taking into account the backflow effect of 3 He by the 4 He in the 3 He- 4 He mixture. The effect contributes solely to the P wave part of the interaction. The repulsive S wave part of the contact interaction contributes to the exchange interaction between the 3 He atoms, while the direct one phonon exchange interaction contributes both to the S and P wave attractive interactions. The overall contribution to the attractive interaction is dominated by the P wave part and the superfluidity in the P wave is more predominant than in the S wave for the 5 % dilute 3 He- 4 He solution, and vice versa for the 1.3 % solution. (author)

  14. Specific-heat measurements on dilute 3He-4He mixtures

    International Nuclear Information System (INIS)

    Zeeuw, H.C.M. van der.

    1985-01-01

    The author measured the specific heat of dilute 3 He- 4 He mixtures in the concentration range from X = 1 x 10 -3 to X = 3 x 10 -3 and in the temperature range from 100 mK to 600 mK. This has been done by means of a thermal relaxation method. This method provides some interesting features and is applied, to our knowledge, for the first time to dilute 3 He- 4 He mixtures. To reach the required temperature range for our experiments a 4 He circulating 3 He- 4 He dilution refrigerator has been constructed. The results confirm the deviation of the 3 He contribution to the specific heat from the ideal Fermi gas behaviour. (Auth.)

  15. Infrared spectra of 4HeH+, 4HeD+, 3HeH+, and 3HeD+

    International Nuclear Information System (INIS)

    Crofton, M.W.; Altman, R.S.; Haese, N.N.; Oka, T.

    1989-01-01

    Isotopic species of the HeH + molecular ion provide an excellent testing ground for studying isotopic dependence of vibration--rotation constants because of the small masses of He and H isotopes. We have observed infrared spectra of the hot band v=2 left-arrow 1 of HeH + and fundamental bands of isotopic species HeD + , 3 HeH + , and 3 HeD + , and obtained the Dunham coefficients Y kl , and the isotopically independent parameters U kl , Δ He kl , and Δ H kl

  16. The sup(40,44,48)Ca(3He, 3He) and (3He, 4He) reactions at 50 MeV

    International Nuclear Information System (INIS)

    Griffiths, R.J.; Duggan, F.; Clarke, N.M.

    1981-01-01

    Measurements have been made of the ( 3 He, 3 He) and ( 3 He, 4 He) reactions on the isotopes of calcium 40 Ca, 44 Ca and 48 Ca at an energy of 50.4 MeV. The results have been analysed with conventional optical potentials and DWBA. The adequacy of the former and inadequacy of the latter for reactions with composite particles is discussed. (author)

  17. Kinetic energy of He atoms in liquid 4He-3He mixtures

    International Nuclear Information System (INIS)

    Senesi, R.; Andreani, C.; Fielding, A.L.; Mayers, J.; Stirling, W.G.

    2003-01-01

    Deep inelastic neutron scattering measurements on liquid 3 He- 4 He mixtures in the normal phase have been performed on the VESUVIO spectrometer at the ISIS pulsed neutron source at exchanged wave vectors of about q≅120.0 A -1 . The neutron Compton profiles J(y) of the mixtures were measured along the T=1.96 K isotherm for 3 He concentrations, x, ranging from 0.1 to 1.0 at saturated vapor pressures. Values of kinetic energies of 3 He and 4 He atoms as a function of x, (x), were extracted from the second moment of J(y). The present determinations of (x) confirm previous experimental findings for both isotopes and, in the case of 3 He, a substantial disagreement with theory is found. In particular (x) for the 3 He atoms is found to be independent of concentration yielding a value 3 (x=0.1)≅12 K, much lower than the value suggested by the most recent theoretical estimates of approximately 19 K

  18. Thermodynamic properties of 3He--4He mixtures near Tlambda

    International Nuclear Information System (INIS)

    Kakizaki, A.; Satoh, T.

    1976-01-01

    In order to investigate 3 He impurity effects on the superfluid transition, measurements were made on the thermodynamic quantities, specific heat, thermal expansion coefficients, and pressure dependence of the lambda-transition temperature of three 3 He-- 4 He mixtures and pure 4 He in the neighborhood of the lambda-transition temperature under their saturated vapor pressure. Making use of these measured quantities, it is shown that the so-called Pippard--Buckingham--Fairbank relation holds for 3 He-- 4 He mixtures as well as for pure 4 He, at least in the temperature region of 10 -4 K less than or equal to absolute value (T - T/sub lambda/) less than or equal to 10 -2 K. Based on this, the 3 He impurity effects on the behavior of the specific heat near the lambda-transition are discussed

  19. 3He flow in dilute 3He-4He mixtures at temperatures between 10 and 150 mK

    International Nuclear Information System (INIS)

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

    1985-01-01

    The mutual friction between 3 He and 4 He II below 150 mK has been studied. Empirical relations for the adiabatic and the nonadiabatic flow properties of 3 He moving through 4 He have been determined using a dilution refrigerator with a single mixing chamber. The validity of the relations is verified by osmotic-pressure measurements and by measuring the properties of a double-mixing-chamber system. It is shown that superleak shunts have a strong effect on the flow characteristics. From the nonadiabatic flow properties an expression is derived for the mutual-friction-force density between 3 He and 4 He II. This has a strong resemblance to the Gorter-Mellink mutual-friction-force density between the normal and the superfluid components in pure 4 He II. It is speculated that the 3 He flow in our systems generates a 4 He vortex tangle, which leads to the observed mutual friction between 3 He and 4 He and also to a strong clamping of the 4 He to the walls

  20. Specific heat of 4He and 3He--4He mixtures at their lambda transition

    International Nuclear Information System (INIS)

    Gasparini, F.M.; Moldover, M.R.

    1975-01-01

    We have measured the specific heat near the lambda transition of pure 4 He and of five 3 He-- 4 He mixtures up to a mole fraction of 0.39 3 He in 4 He. Our data for 4 He confirm the results of Ahlers revealing an asymmetry in the exponents above and below T/sub lambda/ when the specific heat is represented by a simple-power-law temperature dependence. Our results for these exponents (α = 0.012 plus-or-minus 0.002 and α' = -0.012 plus-or-minus 0.004) differ somewhat from Ahlers's. Our results can be reconciled with the requirement of scaling (α = α') only by supposing substantial contributions to C/sub p/ are made by singular correction terms to a simple power law. The measured specific heat of the mixtures richest in 3 He appears to be finite, continuous, and cusped at the lambda line. These qualitative features have been termed ''renormalization'' by Fisher. An analysis of our mixture data with a power-law temperature dependence does not yield a fully renormalized exponent, but rather an effective exponent. Derivatives at the lambda line were used to calculate the specific heat along paths of constant pressure and constant relative chemical potential.This specific heat behaves very much like C/sub p/ of pure 4 He, this behavior supporting the idea of universality for the specific-heat exponents. It is also true that the same asymmetry in the branches above and below T/sub lambda/ which is []bserved in pure 4 He is retained in the mixtures. The persistence of the asymmetry of C/subp//sub phi/ as one moves along the lambda line towards increasing 3 He concentration (at the saturated vapor pressure of the mixtures) is analogous to the persistence of the asymmetry of C/subp/ as one moves along the lambda line towards increasing pressure in pure 4 He

  1. Spin waves at the liquid 3He-4He interface

    International Nuclear Information System (INIS)

    Heff, A.; Candela, D.; Edwards, D.O.; Kumar, S.

    1987-01-01

    The properties of various interfaces in helium and, in particular, the interface between liquid 3 He and a solution of 3 He in 4 He, may be studied using spin waves. Assuming no transverse relaxation, the boundary condition for the transverse magnetization contains one complex kinetic coefficient, b. For the normal 3 He to 3 He- 4 He interface, b is related to the 3 He quasi-particle transmission probability antiτ, which we estimate from a simple model. A calculation of the spin wave absorption spectrum for a typical geometry shows that b and antiτ may be measured by NMR. Neither b nor antiτ is greatly affected when the pure 3 He enters the A phase, but both are strongly reduced in the B phase

  2. Heat pulses in dilute 3He-4He mixtures

    International Nuclear Information System (INIS)

    Husson, L.P.J.

    1983-01-01

    The propagation of heat pulses in dilute 3 He- 4 He mixtures under pressure along a tube, which is long compared to its diameter, is discussed. At high temperatures, where the excitations are in local equilibrium with one another, the propagation of heat pulses in the liquid is determined by the phenomenon of second sound, which is essentially a density wave in the excitation gas. The velocity and attenuation of second sound can be determined from the shape of the transmitted pulse. Measurements on the scattering and absorption of phonons are presented, together with a detailed description of the experimental technique and the electronic equipment. Measurements on the velocity and absorption of second sound are presented. From the results for the velocity of second sound in pure 4 He, values of the phonon and roton parameters are deduced. The velocity data in the mixtures have been used to calculate values of the effective mass of 3 He in superfluid 4 He. The results of these calculations have been compared with values of the effective mass obtained by other authors. The coefficient of second-sound absorption in pure 4 He is computed from theory, making use of the phonon and roton parameters calculated from the second-sound velocity data in pure 4 He. The experimental results on the scattering and absorption of phonons have been analysed. The empirical expressions for the scattering and absorption rates obtained from the diffusive phonon signals were compared with the results of the Baym-Ebner theory, and have also been used to calculate the coefficient of thermal conductivity in dilute 3 He- 4 He mixtures. (Auth.)

  3. Mobility of ions trapped on vortex lines in pure 4He and 3He--4He solutions

    International Nuclear Information System (INIS)

    Ostermeier, R.M.; Glaberson, W.I.

    1976-01-01

    Measurements have been made of the mobility of positive and negative ions trapped on vortex lines in pure 4 He and dilute 3 He-- 4 He solutions over the temperature range 1.6 greater than T greater than 0.3 K. In pure 4 He below about 0.7 K, several new effects not seen at higher temperatures are observed and are not easily explained with existing theories. Most notable are an enhanced broadening of the ion pulse and a rapid increase in the mobility with decreasing temperature. Measurements of the electric field dependence of the drift velocity in pure 4 He at low temperatures show a limiting velocity for sufficiently large fields. This behavior can be explained using a simple resonance theory. The inverse mobility data for solutions show sharp increases at certain critical temperatures, which are interpreted as being associated with the condensation of 3 He atoms onto the vortex cores. The dependence of the critical temperature on the bulk 3 He concentration is found to be in good agreement with a simple condensation theory. An extension of arguments used in this theory to lower temperatures leads to the picture of a 3 He-rich core growing with decreasing temperature, consistent with our lower temperature experimental data

  4. The cross section of 3He(3He,2p)4He measured at solar energies

    International Nuclear Information System (INIS)

    Junker, M.; Arpesella, C.; Bellotti, E.; Broggini, C.; Corvisiero, P.; D'Alessandro, A.; Fiorentini, G.; Fubini, A.; Gervino, G.; Greife, U.; Gustavino, C.; Lambert, J.; Prati, P.; Rodney, W.S.; Rolfs, C.; Trautvetter, H.P.; Zavatarelli, S.

    1999-01-01

    We report on the status of the 3 He( 3 He,2p) 4 He experiment at the underground accelerator facility LUNA (Gran Sasso). The lowest projectile energies for the measured cross section correspond already to energies below the center of the solar Gamow peak (E 0 =22 keV). The data provide no evidence for the existence of a hypothetical resonance in the energy range investigated. Although no extrapolation is needed anymore (except for energies at the low-energy tail of the Gamow peak), the data must be corrected for the effects of electron screening, clearly observed the first time for the 3 He( 3 He,2p) 4 He reaction. The effects are however larger than expected and not understood, leading presently to the largest uncertainty on the quoted S(0) value for bare nuclides (= 5.40 MeVb)

  5. Second sound velocities in superfluid 3He-4He solutions

    International Nuclear Information System (INIS)

    Dikina, L.S.; Kotenev, G.Ya.; Rudavskij, Eh.Ya.

    1978-01-01

    The velocities of the second sound in the superfluid He 3 -He 4 solutions were measured by the pulse method in the range of temperatures from 1.3 K to Tsub(lambda) and for He 3 concentrations up to 13%.The results obtained supplemented by those available before give the complete description of the concentration and temperature dependences of the second sound velocity in superfluid He 3 -He 4 solutions. The comprehensive comparison of the experimental data on the velocity of the second sound with the theoretical calculations for the superfluid solutions with arbitrary content of He 3 is performed. The good agreement is found between experiment and the theory. The experimental data obtained are used for determination of the potential, which determines the properties of the superfluid solutions

  6. Efficient 3He/4He separation in a nanoporous graphenylene membrane.

    Science.gov (United States)

    Qu, Yuanyuan; Li, Feng; Zhao, Mingwen

    2017-08-16

    Helium-3 is a precious noble gas, which is essential in many advanced technologies such as cryogenics, isotope labeling and nuclear weapons. The current imbalance of 3 He demand and supply shortage leads to the search for an efficient membrane with high performance for 3 He separation. In this study, based on first-principles calculations, we demonstrated that highly efficient 3 He harvesting can be achieved in a nanoporous graphenylene membrane with industrially-acceptable selectivity and permeance. The quantum tunneling effect leads to 3 He harvesting with high efficiency via kinetic sieving. Both the quantum tunneling effect and zero-point energy (ZPE) determine the 3 He/ 4 He separation via thermally-driven equilibrium sieving, where the ZPE effect dominates efficient 3 He/ 4 He separation between two reservoirs. The quantum effects revealed in this work suggest that the nanoporous graphenylene membrane is promising for efficient 3 He harvesting that can be exploited for industrial applications.

  7. The production of He-3 and heavy ion enrichment in He-3-rich flares by electromagnetic hydrogen cyclotron waves

    Science.gov (United States)

    Temerin, M.; Roth, I.

    1992-01-01

    A new model is presented for the production of He-3 and heavy ion enrichments in He-3-rich flares using a direct single-stage mechanism. In analogy with the production of electromagnetic hydrogen cyclotron waves in earth's aurora by electron beams, it is suggested that such waves should exist in the electron acceleration region of impulsive solar flares. Both analytic and test-particle models of the effect of such waves in a nonuniform magnetic field show that these waves can selectively accelerate He-3 and heavy ions to MeV energies in a single-stage process, in contrast to other models which require a two-stage mechanism.

  8. Annihilation of antiprotons at rest in 3He and 4He

    International Nuclear Information System (INIS)

    Balestra, F.; Bossolasco, S.; Bussa, M.P.; Busso, L.; Fava, L.; Ferrero, L.; Panzieri, D.; Piragino, G.; Tosello, F.; Bendiscioli, G.; Rotondi, R.; Salvini, P.; Zenoni, A.; Batusov, Y.A.; Bunyatov, S.A.; Falomkin, I.V.; Nichitiu, F.; Pontecorvo, G.B.; Sapozhnikov, M.G.; Tretyak, V.I.; Guaraldo, C.; Maggiora, A.; Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.M.; Breivik, F.O.; Jacobsen, T.; Sorensen, S.O.

    1987-01-01

    At LEAR of CERN the annihilation of antiprotons stopping in 3 He and 4 He filling a self shunted streamer chamber in magnetic field has been studied. The relative probabilities of π - production in anti p 3 He and anti p 4 He annihilation events have been obtained. The ratio between the anti p annihilation probability on the neutron and on the proton for 3 He and 4 He has been deduced to be about half the value obtained for 2 H in bubble chamber experiments. The analysis of the results shows this difference cannot be ascribed only to the pion final state interaction or to the shadow effect of the nucleons in the nuclei. 9 refs.; 2 figs

  9. Third sound resonance studies of 3He-4He mixture films

    International Nuclear Information System (INIS)

    Heinrichs, R.M.

    1985-01-01

    Third sound velocity and dissipation measurements were performed on 3 He- 4 He mixture films of 3.6 and 5.3 layers 4 He and up to 3 added layers 3 He in the temperature range 0.05-0.3 K using third sound resonance techniques. The 3 He concentration dependence of the velocity was in excellent agreement with a simple layered film model down to the lowest concentrations studied. At the higher 3 He concentrations, the velocity began to deviate from the model, rising above it. The concentration dependence of the dissipation showed some unique structure with a maximum at 0.3-0.5 layers added 3 He for both 4 He coverages. The third sound velocity in the low concentration mixture films had very little temperature dependence in the range studied. The dissipation, however, had some definite temperature dependent structure that evolved with concentration. This evolution was most pronounced at concentrations near the dissipation maximum and eventually became exponential at the higher coverages. Fitting these exponentials produced estimates of the difference in binding energy for the 3 He states in and on the film. In this higher 3 He concentration regime, a temperature dependence of the velocity was observed that began as a small peak at about 0.15 K and eventually became a step at the highest concentrations studied. The exponential nature of the dissipation became clouded when the velocity evolved into this last behavior

  10. Δ excitation in 3He and 4He by photons

    International Nuclear Information System (INIS)

    Maruyama, Koichi.

    1993-06-01

    The use of the 3 He and 4 He photodisintegration reactions in the study of the excitation, propagation, and decay of the Δ (1232) in these nuclei is proposed. By using the data obtained with TAGX for both photon absorption on neutron-proton pairs and complete photodisintegration, we find no compelling evidence for the change of the Δ property in the 3 He and 4 He nuclei. It is also proposed to use nuclear photodisintegration in the search for the excitation of the higher-mass nucleon resonances whose absence in the total photon-absorption cross sections in nuclei is reported recently. (author)

  11. Annihilation of antiprotons at rest in 3He and 4He

    International Nuclear Information System (INIS)

    Balestra, F.; Bossolasco, S.; Bussa, M.P.; Busso, L.; Fava, L.; Ferrero, L.; Panzieri, D.; Piragino, G.; Tosello, F.; Bendiscioli, G.; Rotondi, A.; Salvini, P.; Zenoni, A.; Batusov, Yu.A.; Bunyatov, S.A.; Falomkin, I.V.; Nichitiu, F.; Pontecorvo, G.B.; Sapozhnikov, M.G.; Tretyak, V.I.; Guaraldo, C.; Maggiora, A.; Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.M.; Breivik, F.O.; Jacobsen, T.; Soerensen, S.O.

    1987-01-01

    At LEAR of CERN the annihilation of antiprotons, stopping in 3 He and 4 He filling a self-shunted streamer chamber in a magnetic field, has been studied. The charged-particle multiplicities have been measured and the relative probabilities of π - production in anti p 3 He and anti p 4 He annihilation events have been obtained. The ratio between the anti p annihilation probability on the neutron and the proton for 3 He and 4 He has been deduced to be about half the value obtained for 2 H in bubble chamber experiments. The analysis of the results shows that this difference cannot be due only to the pion final-state interaction or to the shadow effect of the nucleons of the nuclei. The probability of anti p annihilation at rest on a proton bound in the nucleus results to be twice as high as that on a bound neutron, showing the dominance of annihilation in the I=0 isospin states. (orig.)

  12. Dynamics of phase-separated 3He-4He films

    International Nuclear Information System (INIS)

    Kurihara, Susumu

    1982-01-01

    A froehlich-type Hamiltonian is derived for third sound and 3 He quasi particles in phase-separated double layer of superfluid 4 He and normal 3 He liquid. It is stressed that our system is unique and valuable in that characteristic parameters can be varied in a wide range, simply by adjusting the film thickness. The effect of fermion-boson coupling on the velocity and damping of the third sound is examined. It is predicted that a rather drastic change in the third sound spectrum will occur when the Fermi velocity of 3 He system and the third sound velocity are nearly the same. It is pointed out that the system under consideration may show a variety of interesting phenomena, in addition to the softening of the third sound. (author)

  13. Effects of Δ-isobar degrees of freedom on the reactions 3He(n,γ)4He and 3He(p,e+νe)4He at low-energy

    International Nuclear Information System (INIS)

    Schiavilla, R.

    1991-01-01

    The cross sections of the radiative 3 He(n,γ) 4 He and weak 3 He(p,e + ν e ) 4 He capture reactions at thermal neutron and keV proton energies have been calculated with the Variational Monte Carlo method. The ground state and low-energy continuum wave functions have been determined variationally from a realistic Hamiltonian, and include both nucleon and Δ-isobar degrees of freedom. The electroweak transition operator contains one- and two-body components in the N + Δ Hilbert space

  14. Effective interactions in dilute mixtures of 3He in 4He

    International Nuclear Information System (INIS)

    Hsu, W.; Pines, D.

    1985-01-01

    Nonlocal pseudopotentials which describe the effective interaction between 3 He quasiparticles, and between these quasiparticles and the background 4 He liquid, are obtained as a function of concentration and pressure by generalizing the Aldrich--Pines pseudopotentials for pure 3 He and 4 He to dilute mixtures. The hierarchy of physical effects which determine these pseudopotentials is established. Interaction-induced short-range correlations are the dominant physical feature; next in order of importance is the greater zero point motion associated with the replacement of a 4 He atom by a 3 He atom, while spin-duced ''Pauli principle'' correlations play a significantly smaller, albeit still important role. We find a consistent trend in the change of the effective direct quasiparticle interactions with increasing concentration, and show how the Aldrich-Pines pseudopotentials for pure 3 He quasiparticles represent a natural extension of our results for dilute mixtures. Our calculated nonlocal pseudopotential for 3 He quasiparticles is qualitatively similar to that proposed by Bardeen, Baym, and Pines; it changes sign at somewhat lower momentum transfers than the BBP result, varies little with concentration, and provides a physical basis for understanding the BBP result. The effective interaction between quasiparticles of parallel spin, here determined for the first time, is essentially repulsive in the very dilute limit; as the concentration increases, it becomes increasingly attractive at low momentum transfers, and resembles closely that between antiparallel spin quasiparticles at 5% concentration. The concentration-dependent transport properties calculated from these pseudopotentials (which involve only one phenomenological parameter) are in good agreement with experiment at saturated vapor pressure (SVP), 10 atm, and 20 atm

  15. Giant asymmetry of separation and homogenization processes in solid 3He-4He solutions

    International Nuclear Information System (INIS)

    Grigor'ev, V.N.; Majdanov, V.A.; Penzev, A.A.; Polev, A.V.; Rubets, S.P.; Rudavskij, Eh.Ya.; Rybalko, A.S.; Syrnikov, E.V.

    2005-01-01

    The kinetics of the processes of separation and homogenization of solid 3 He- 4 He solutions is compared by using the precision barometry. The experiments were made with the initial specimens of three types: weak 3 He- 4 He and 4 He- 3 He solutions and concentrated 3 He- 4 He ones. It is found that the homogenization rate at the initial stage may be more than 500 times higher that the rate of separation. This is the case for all types of the solutions studied. The appreciable rate of phase separation in the concentrated solutions where, according to the modern concepts, impurity atoms in quantum crystals should be localized, suggests that in such conditions there is a new unknown mechanism of mass-transfer, while the fast homogenization points to a nondiffusion nature of the process

  16. Superfluidity in two-dimensions. A thermal conductivity study of 4He and 3He- 4He mixture films

    International Nuclear Information System (INIS)

    Finotello, D.

    1992-01-01

    We review measurement of the thermal transport of 4 He films and 3 He- 4 He mixture films near the superfluid transition. These measurements were performed on helium films of thickness ranging from 12 to 156 A and mixture films with 3 He concentration up to 2%. The superfluid transition temperature for these films ranged from 1.2 to 2.2. K. We discuss universal features of the data as well as the behavior of the ratio of the vortex diffusion constant to vortex core-parameter, the sharpness of the transition and the superfluid transition temperature as a function of thickness and concentration. We also describe new experiments that will contribute to a better understanding of the observed behavior (Author)

  17. Phase equilibrium in a polarized saturated 3He-4He mixture

    International Nuclear Information System (INIS)

    Rodrigues, A.; Vermeulen, G.

    1997-01-01

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

  18. Capture of ions by vortex lines in pure 4He and 3He--4He solutions

    International Nuclear Information System (INIS)

    Ostermeier, R.M.; Glaberson, W.I.

    1975-01-01

    Measurements of the capture cross section for the negative ion by vortex lines in pure 4 He and a 0.94 percent solution of 3 He in 4 He are presented. A measurable capture of positive ions was not observed in either system. In pure 4 He the departure of the experimental data from the predictions of stochastic theory at lower temperatures is explained in terms of a simple breakdown in that theory, and lifetime effects are shown to be of only secondary importance. The decrease in cross section with decreasing temperature, due essentially to a reduced number density of rotons, is predicted by the results of a Monte Carlo calculation. The cross section in the solution follows stochastic theory to significantly lower temperatures, but at about 1 K there again occurs a marked discrepancy. Measurements of the ion trapping lifetime at low temperatures indicate that it is the finite lifetime that accounts for this discrepancy. Elimination of lifetime effects results in fair agreement between the cross section data in the solution and the predictions of stochastic theory. (11 figures) (auth)

  19. 3He(d,p)4He reaction calculation with three-body Faddeev equations

    International Nuclear Information System (INIS)

    Oryu, S.; Uzu, E.; Sunahara, H.; Yamada, T.; Tabaru, G.; Hino, T.

    1998-01-01

    In order to investigate the 3 He-n-p system as a three-body problem, we have formulated 3 He-n and 3 H-p effective potentials using both a microscopic treatment and a phenomenological approach. In the microscopic treatment, potentials are generated by means of the resonating group method (RGM) based on the Minnesota nucleon-nucleon potential. These potentials are converted into separable form by means of the microscopic Pauli correct (MPC) method. The MPC potentials are properly formulated to avoid Pauli forbidden states. The phenomenological potentials are obtained by modifying parameters of the EST approximation to the Paris nucleon-nucleon potential, such that they fit the low-energy 3 He-n, 3 H-p, and 3 He-p phase shifts. Therefore, they describe the 3 He-n differential cross section, the polarization observables, and the energy levels of 4 He. The 3 He-n-p Faddeev equations are solved numerically. We reproduce correctly the ground state and the first excited state of 5 Li. Furthermore, the Paris-type potential is used to investigate the 3 He(d,p) 4 He reaction at a deuteron bombarding energy of 270 MeV, where the system is treated as a three-body problem. Results for the polarized and unpolarized differential cross sections demonstrate convergence of the Born series. (orig.)

  20. The effect of Demkov coupling in the rotational predissociation of 3He4He+, ch. 4

    International Nuclear Information System (INIS)

    Asselt, N.P.F.B. van; Maas, J.G.; Los, J.

    1976-01-01

    The momentum distribution of the 3 He + and the 4 He + fragments, both originating from rotational predissociation of 3 He 4 He + has been measured. There is a pronounced difference between the intensity distributions in both spectra. This difference is explained as the result of a Demkov coupling between the two lowest electronic states of the molecular ion. The rotational quantum numbers of the states involved are calculated from the spectra

  1. Study of the sup 3 H( sup 3 H, 2n) sup 4 He and sup 3 He( sup 3 He, 2p) sup 4 He reactions in the framework of three-cluster microscopic model

    CERN Document Server

    Vasilevsky, V S; Arickx, F; Broeckhove, J

    2002-01-01

    The reactions sup 3 H( sup 3 H, 2n) sup 4 He and sup 3 He( sup 3 He, 2p) sup 4 He are investigated within a fully microscopic cluster model featuring a three-cluster exit channel. A Hyperspherical Harmonics basis is used to describe the three-cluster continuum. The resulting astrophysical s-factor of both reactions is in good agreement with experimental data. Analysis of the low-energy scattering parameters reveals no evidence for a hidden resonance state would increase the cross-section of the reactions, and would help to resolve the solar neutrino problem.

  2. Experimental considerations on producing highly polarized liquid 3He in a matrix of solid 4He

    International Nuclear Information System (INIS)

    Greenberg, A.S.; Hebral, B.; Papoular, M.; Beal-Monod, M.T.

    1980-01-01

    Two experiments are briefly reviewed in which droplets of 3 He were formed in solid 4 He. These experiments indicate such conditions are favorable for the production of quasi-stable highly polarized liquid 3 He. A solid solution of dilute 3 He in 4 He is proposed as a promising system to produce experimentally realizable highly polarized liquid 3 He using the Castaing-Nozieres decompression

  3. Variations of 3/He/4He isotope ratios within the Broadlands geothermal field, New Zealand

    International Nuclear Information System (INIS)

    Hulston, John; Lupton, John; University of California, Santa Barbara; Rosenberg, Nina

    1986-01-01

    The Broadlands-Ohaaki geothermal field is located 20 km NE of Wairakei on the Central Volcanic Zone of New Zealand. It falls within a resistivity low extending 4 km by 3 km. A study of 3 He/ 4 He ratios within this field has shown R/R A ratios close to 6.0 in the Ohaaki production area (NW). In contrast the production area to the SE on the east bank of the Waikato River has R/R A values close to 3.5. Differences in chemical ratios reported previously are found to correlate with the 3 He/ 4 He measurements. A tentative interpretation of the results indicate that there is a contribution of 3 He from the mantle and that the variations in the 3 He/ 4 He ratios are probably related to differences in the geochemistry of the rocks through which the geothermal fluids flow to the surface. Preliminary measurements of the argon isotopes also show a contribution from radiogenic rocks at depth

  4. Growth and dissolution of liquid 3He droplets in solid 4He matrix

    International Nuclear Information System (INIS)

    Gan'shin, A.N.; Grigor'ev, V.N.; Majdanov, V.A.; Penzev, A.A.; Rudavskij, Eh.Ya.; Rybalko, A.S.

    2000-01-01

    The phase separation kinetics of solid 3 He - 4 He mixtures was investigated using pressure measurements in the conditions when the two-phase system formed consists of concentrated phase liquid droplets (almost pure 3 He) in the dilute phase crystal matrix (almost pure 4 He). It is shown that the liquid droplet growth may be described by a sum of two exponential processes with small and large time contacts as cooling down step by step. This is a result of the strong influence of strains which appear in the crystal at the phase separation due to a large difference in molar volume between the phases and probably give rise to plastic deformation of the matrix and to non-equilibrium 3 He concentration in it. The 3 He atom transfer occurs only to the extent of strain relaxation. It is found that the cyclic growth and dissolution of the liquid droplets affect the crystal quality and lead to pressure increase. The coexistence of liquid and solid phases in droplets is speculated to be possible

  5. Application of the three-body model to the reactions 6Li(3He,t 3He)3He and 6Li(3He,3He3He)3H

    International Nuclear Information System (INIS)

    Haftel, M.I.; Allas, R.G.; Beach, L.A.; Bondelid, R.O.; Petersen, E.L.; Slaus, I.; Lambert, J.M.; Treado, P.A.

    1977-01-01

    Experimental and theoretical cross sections are presented for the 6 Li( 3 He, 3 He 3 He) 3 H and 6 Li( 3 He,t 3 He) 3 He reactions for the symmetric angle pairs 20 0 -20 0 , 28.3 0 -28.3 0 , and 35 0 -35 0 . The theoretical cross sections are calculated in a three-body model where the trions (i.e., mass-3 nuclei) are treated as elementary particles with 6 Li being a 3 He- 3 H bound state. The trion-trion interaction is represented by S wave separable potentials with the breakup cross sections calculated with the tree-body Haftel-Ebenhoeh code. the Coulomb interaction is taken into account by fitting the separable potential parameters to the trion-trion scattering data and is included approximately in the breakup code. The experimental cross sections are compared with both the plane-wave impulse approximation and the three-body model predictions. The plane-wave impulse approximation predicts both the shapes and magnitudes poorly (10 to 20 times experiment). Without Coulomb corrections the three-body model gives good agreement with experiment for the shapes of the spectra with the magnitudes generally being about 40% of experiment for 6 Li( 3 He, 3 He 3 He) 3 H and about 80% for 6 Li( 3 He,t 3 He) 3 He. The Coulomb corrections improve the magnitudes predicted by the three-body model but not the shapes. It is observed that for these reactions S wave separable potentials describe the breakup data much better than they do the two-body trion-trion scattering data. This result should encourage further three-body treatment of these and similar reactions

  6. Structure properties of the 3He-4He mixture at T = O K

    International Nuclear Information System (INIS)

    Boronat, J.; Polls, A.; Fabrocini, A.

    1993-01-01

    The spatial structure properties of 3 He- 4 He mixtures at T = O K are investigated using the hypernetted-chain formalism. The variational wave function used to describe the ground-state of the mixture is a simple generalization of the trial wave functions for pure phases and contains two- and three-body correlations. The elementary diagrams are taken into account by means of an extension of the scaling approximation to the mixtures. The two-body distribution (g (α,β) (r)) and the structure functions (S (α,β) (k)) together with the different spin-spin distribution functions for the 3 He component in the mixture are analyzed for several concentrations of 3 He. Two sum-rules, for the direct and the exchange part of the g (3,3) (r), are used to ascertain the importance of the full treatment of the Fermi statistics in the calculation. The statistical correlations are found responsible for the main differences between the several components of the distribution function. Due to its low concentration, 3 He behaves as a quasi-free Fermi gas, as far as the statistical correlations are concerned, although it is strongly correlated with the 4 He atoms through the interatomic potential

  7. Regional and temporal variations in CO2/3He, 3He/4He and δ13C along the North Anatolian Fault Zone, Turkey

    International Nuclear Information System (INIS)

    Leeuw, G.A.M. de; Hilton, D.R.; Guelec, N.; Mutlu, H.

    2010-01-01

    New He and C relative abundance, isotope and concentration results from nine geothermal locations situated along an 800-km transect of the North Anatolian Fault Zone (NAFZ), Turkey, that were monitored during the period November 2001-November 2004, are reported. The geothermal waters were collected every 3-6 months to study possible links between temporal geochemical variations and seismic activity along the NAFZ. At the nine sample locations, the He isotope ratios range from 0.24 to 2.3R A , δ 13 C values range from -4.5 to +5.8 per mille, and CO 2 / 3 He ratios range from 5 x 10 9 to 5 x 10 14 . The following geochemical observations are noted: (1) the highest 3 He/ 4 He ratios are found near the Galatean volcanic region, in the central section of the NAFZ, (2) at each of the nine sample locations, the 3 He/ 4 He ratios are generally constant; however, CO 2 / 3 He ratios and He contents both show one order of magnitude variability, and δ 13 C values show up to ∼4 per mille variability, and (3) at all locations (except Resadiye), δ 13 C values show positive correlations with CO 2 contents. The results indicate that at least three processes are necessary to account for the geochemical variations: (1) binary mixing between crustal and mantle-derived volatiles can explain the general characteristics of 3 He/ 4 He ratios, δ 13 C values, and CO 2 / 3 He ratios at the nine sample locations; (2) preferential degassing of He from the geothermal waters is responsible for variations in CO 2 / 3 He values and He contents at each sample location; and (3) CO 2 dissolution followed by calcite precipitation is responsible for variations in CO 2 contents and δ 13 C values at most locations. For each of the geochemical parameters, anomalies are defined in the temporal record by values that fall outside two standard deviations of average values at each specific location. Geochemical anomalies that may be related to seismic activity are recorded on June 28, 2004 at Yalova

  8. Homogeneous nucleation in phase separation of solid 3He-4He mixtures

    International Nuclear Information System (INIS)

    Poole, M.; Smith, A.; Maidanov, V.A.; Rudavskii, E.Ya.; Grigor'ev, V.N.; Slezov, V.V.; Saunders, J.; Cowan, B.

    2003-01-01

    NMR and pressure have been measured during phase separation in solid 3 He- 4 He mixtures. Spin echoes were used to observe bounded diffusion and to estimate the diffusion coefficient, size and nuclei concentration in the 3 He-enriched phase. The characteristic phase separation time constant of the mixture was found from pressure measurements. The results argue convincingly for homogeneous nucleation. The surface tension of the nuclei is found independently from NMR and from pressure measurements; the two determinations agree well and yield a surface tension coefficient of 4.9x10 -6 J m -2

  9. 4He(γ,n)3He photodisintegration and the properties of O+-resonance of 4He by the resonating group method

    International Nuclear Information System (INIS)

    Filippov, G.F.; Vasilevsky, V.S.; Kovalenko, T.P.

    1984-01-01

    The reaction of 4 He electrodisintegration at small momenta transfered to the nucleus by electrons is considered on the basis of an algebraic version of the resonating group method. The calculated matrix element of the monopole transition from the ground state of 4 He into the O + -resonance state and the calculated monopole energy weighted sum rules confirm the assumption on the cluster nature of O + -resonance. In the dipole approximation the photonuclear reaction of 4 He(γ, n)He 3 at small energies of γ-quanta is studied. The obtained values of the electric dipole transition probabilities and the effective cross sections reveal a good agreement with experimental data

  10. The osmotic pressure of 3He-4He mixtures along the phase separation curve

    NARCIS (Netherlands)

    van de Klundert, L.J.M.; Bos, M.R.E.; van der Meij, J.A.M.; Steffens, H.A.

    1977-01-01

    The osmotic pressure of 3He-4He mixtures was measured along the phase separation curve at temperatures up to 500 mK by balancing it with the fountain pressure of pure 4He. The usefullness of the secondary osmotic pressure thermometer was reinvestigated.

  11. The osmotic pressure of 3He-4He mixtures along the phase separation curve

    International Nuclear Information System (INIS)

    Klundert, L.J.M. van de; Bos, M.R.E.; Meij, J.A.M. van der; Steffens, H.A.

    1977-01-01

    The osmotic pressure of 3 He- 4 He mixtures was measured along the phase separation curve at temperatures up to 500 mK by balancing it with the fountain pressure of pure 4 He. The usefullness of the secondary osmotic pressure thermometer was reinvestigated. (Auth.)

  12. X-ray Debye-Waller factor measurements of solid 3He and 4He

    International Nuclear Information System (INIS)

    Arms, D.A.; Shah, R.S.; Simmons, R.O.

    2003-01-01

    X-ray synchrotron radiation was used to measure Debye-Waller factors of helium crystals for both 3 He and 4 He in both hcp and fcc phases. To our knowledge, there are no previous measurements for 3 He. The ranges studied for 3 He and 4 He crystals were 11.52-12.82 and 10.95-12.13 cm 3 , respectively, and 11.5-18.2 and 12.0-20.3 K. With small uncertainty, only a Gaussian dependence upon momentum transfer Q was found, and no anisotropy was detected in the hcp phase. Mean square atomic deviations, 2 >, and Lindemann ratios were obtained. Large Lindemann ratios confirm that these solids are highly anharmonic. The 2 > values agree within an average 1% with computations of Draeger and Ceperley from path integral Monte Carlo methods including unusual extrapolations to the thermodynamic limit. Because the path-integral Monte Carlo (PIMC) computations exhibit a T 3 dependence for 2 >, which also depends upon molar volume, an empirical analysis was made of the present data as well as of published x-ray and neutron data on hcp 4 He. The volume dependencies are similar to those found from calorimetry, over a large volume range, and the temperature dependencies show similar systematic variations with molar volume both in x-ray data and PIMC results

  13. Thermal transport properties in dilute 3He-4He mixtures near the superfluid transition

    International Nuclear Information System (INIS)

    Tuttle, J.G.

    1991-01-01

    The author describes measurements of various transport properties of dilute liquid 3 He- 4 He mixtures in two different sample cells. One cell was designed to measure the temperature drop ΔT across a fluid layer due to an applied heat flux Q, and the other allowed measurement of both ΔT and ΔX, the molar concentration drop. He studied the anomalous boundary resistance, ΔR b , in superfluid 4 He near T λ for Q between 4 and 100μW/cm 2 . He presents results for both the weakly divergent and the heat dependent, more strongly divergent contributions. He compares his data with those of Duncan and Ahlers and with theoretical predictions by Frank and Dohm. He also presents similar R b data for a mixture with X = 2.5 x 10 -6 . He determined the relaxation time τ for transients observed during thermal conductivity κ eff and thermal diffusion k T * measurements in superfluid mixtures between 1.7K and T λ with X ranging from 10 -6 to 5 x 10 -2 . He compares these results, taken with a fluid layer thickness h = 1.81 mm, with theoretical predictions and with earlier data for h = 1.47 mm. He shows the mass diffusion coefficient D computed both from τ and from κ eff data for 0.001 λ , and he compares the results of these two different determinations. In addition, he presents the 3 He-roton scattering cross section calculated using D results. In the normal phase he measured the thermal diffusion ratio k T and the thermal conductivity κ for 0.009 ≤ X ≤ 0.05 near T λ , and he compares these results with predictions by Dohm and Folk

  14. Study of the 6Li + p → 3He + 4He reaction in inverse kinematics

    International Nuclear Information System (INIS)

    Betsou, C.; Pakou, A.; Aslanoglou, X.; Nicolis, N.G.; Sgouros, O.; Soukeras, V.; Cappuzzello, F.; Acosta, L.; Agodi, C.; Carbone, D.; Cavallaro, M.; Di Pietro, A.; Fernandez-Garcia, J.P.; Figuera, P.; Fisichella, M.; Foti, A.; Keeley, N.; Marquinez-Duran, G.; Martel, I.; Mazzocco, M.; Strano, E.; Torresi, D.; Pierroutsakou, D.; Rusek, K.; Stiliaris, E.

    2015-01-01

    Angular distribution measurements were performed for the 6 Li + p → 3 He + 4 He reaction in inverse kinematics at incident energies of 2.7, 3.3, 4.2 and 4.8 MeV/u. The detection of both recoils ( 3 He and 4 He) over the laboratory angle range θ lab = 16 circle to 34 circle allowed the determination of the angular distribution over a wide angular range in the center-of-mass frame (θ c.m. ∝ 40 circle to 140 circle ). The results clarify inconsistencies between existing data sets and are consistent with compound nucleus model calculations. (orig.)

  15. Nonlinear second- and first-sound wave equations in 3He-4He mixtures

    International Nuclear Information System (INIS)

    Mohazzab, Masoud; Mulders, Norbert

    2000-01-01

    We derive nonlinear Burgers equations for first and second sound in mixtures of 3 He- 4 He, using a reductive perturbation method and obtain expressions for the nonlinear and dissipation coefficients. We further find a diffusion equation for a coupled temperature-concentration mode. The amplitude of first (second) sound generated from second (first) sound in mixtures is also derived. Our derivation includes the dependence of thermodynamical quantities on temperature, pressure, and 3 He concentration, and is valid up to a first order in terms of the isobaric expansion coefficient. We show that close to the λ line the nonlinearity of second sound in mixtures is enhanced as compared with pure 4 He

  16. Performance of a mass spectrometer for determining low tritium levels from 3He/4He measurements

    International Nuclear Information System (INIS)

    Lynch, M.C.F.; Kay, D.J.

    1981-01-01

    The Micromass 3000 mass spectrometer is based on Clarke's 3 He/ 4 He instrument of McMaster University. The principal special features of the MM3000 are: (i) The double collector system, which uses an electron multiplier for the small 3 He + ion beams and a conventional Faraday detector for 4 He + ; (ii) The high sensitivity ion source; and (iii) The low-volume analyser tube employing static vacuum techniques. The sensitivity, resolution and background of the system are designed to permit measurement of 3 He and 4 He levels of the order of 10 -12 cm 3 STP and 10 -6 cm 3 STP, respectively, with a precision of 0.5%, although smaller quantities are detectable. The inherent resolution of the instrument is well in excess of 2000, but a resolution of 600-1000 is normally used for the 3 He + collector as this is sufficient to separate 3 He + from any interfering HD + or H + 3 ions. At this resolution 900 ions per second of 3 He + ions are obtained from 10 -12 cm 3 STP of 3 He. This is the size of 3 He samples obtained from water samples containing tritium at levels around 200 tritium units (1 tritium unit (TU) = IT/10 18 H). At lower tritium levels the 3 He + signal is correspondingly reduced, but the same techniques (described below) allow signals from 1-TU samples (5 ions/s) to be measured with good precision. The limit of detection is reached with quantities of 3 He in the region of 10 -15 cm 3 STP and tritium levels of around 0.1 TU. (author)

  17. Ab initio study of small He cluster ions Hen+, n=2, 3, 4, 5, and low-lying Rydberg states of He4

    International Nuclear Information System (INIS)

    Staemmler, V.

    1990-01-01

    SCF and CEPA calculations are applied to study the structure of small He cluster ions, He n 3 , n=2, 3, 4, 5 and some low-lying Rydberg states of He 4 . The effect of electron correlation upon the equilibrium structures and binding energies is discussed. He 3 + has a linear symmetric equilibrium geometry with a bond length of 2.35 a 0 and a binding energy D e =0.165 eV with respect to He 2 + +He (experimentally: D 0 =0.17 eV which corresponds to D e ≅0.20 eV). He 4 + is a very floppy molecular ion with several energetically very similar geometrical configurations. Our CEPA calculations yield a T-shaped form with a He 3 + centre (R e =2.35 a 0 ) and one inductively bound He atom (4.39 a 0 from the central He atom of He 3 + ) as equilibrium structure. Its binding energy with respect to He 3 + +He is 0.031 eV. A linear symmetric configuration consisting of a He 2 + centre with a bond length of 2.10 a 0 and two inductively bound He atoms (4.20 a 0 from the centre of He 2 + ) is only 0.02-0.03 eV higher in energy. We expect that in larger He cluster ions structures with He 2 + and He 3 + centres and n-2 or n-3 inductively bound He atoms have nearly the same energies. In He 4 a low-lying metastable Rydberg state ( 3 π symmetry for linear He 4 * , 3 B 1 for the T-shaped form) exists which is slightly stronger bound with respect to He 3 * +He than the corresponding ion. (orig.)

  18. Three-critical phenomena in the He3-He4 mixture

    International Nuclear Information System (INIS)

    Carvalho Filho, C.A.A. de.

    1976-07-01

    A review of the phenomenology of tricritical behaviour in He 3 -He 4 mixtures is made. Starting from a model proposed by Blume, Emery and Griffiths the tricritical transition is investigated by means of the Renormalization Group making use of the Callan-Symanzik equation and usual perturbative methods of Relativistic Quantum Field Theory. Mean-field tricritical exponents and logarithmic corrections are found in a sup(n) unified context. The structure of scaling laws is also studied. (author) [pt

  19. Low-temperature H2-4He and H2-3He targets for operation on an electron beam

    International Nuclear Information System (INIS)

    Gol'dshtejn, V.A.; Lubyanyj, V.V.

    1981-01-01

    Structures and basic characteristics of H 2 - 4 He and H 2 - 3 He low temperature targets are given. Technique of 3 He target filling is described. Initial target cooling up to liquid 4 He temperature and its filling up take near approximately 1 h, at that 4 He flow rate equals 15 l. Repeated filling up of 4 He takes 20 min, and target filling up with 3 He - 10-15 min. Good thermal insulation of a cryostat and targets permits the 4 He target to be operated with an electron beam of a mean current of up to 0.5 μA without filling up 4 He for 70 h. At that flow rate of liquid 4 He amounts to 0.2 l/h, and liquid hydrogen - 0.04 l/h. It is concluded that H 2 - 4 He and H 2 - 3 He targets are reliable and simple in operation and permit to work with accelerated particle beams of intensity corresponding to power release >= 0.5 W without corrections for density change [ru

  20. Specific heat of amorphous 3He films and confined liquid 3He

    International Nuclear Information System (INIS)

    Golov, A.; Pobell, F.

    1995-01-01

    We have measured the heat capacities of 3 He films and liquid 3 He in porous Vycor glass at 10 to 600 mK. With increasing the film thickness front 1 to 3 atomic layers , the specific heat evolves gradually from that typical to solid to that of liquid 3 He. At about 2 atomic layers, however, its low-temperature part is nearly temperature-independent; we interpret this as a result of gradual freezing of spins in an amorphous solid 3 He film with decreasing the temperature. The contribution of liquid 3 He in the center of the Vycor pores can be described as the specific heat of bulk liquid 3 He at corresponding pressures in the range 0 to 28 bar. The thickness of amorphous solid on the pore walls increases with external pressure roughly linearly. Preplating the walls with 4 He allows to determine the positions of 3 He atoms contributing to the surface specific heat at 10 to 50 mK. In addition, the contribution from the specific heat of 3 He- 4 He mixing at 100 to 600 mK is discussed as a function of pressure and amount of 4 He

  1. Effects of {Delta}-isobar degrees of freedom on the reactions {sup 3}He(n,{gamma}){sup 4}He and {sup 3}He(p,e{sup +}{nu}{sub e}){sup 4}He at low-energy

    Energy Technology Data Exchange (ETDEWEB)

    Schiavilla, R.

    1991-12-31

    The cross sections of the radiative {sup 3}He(n,{gamma}){sup 4}He and weak {sup 3}He(p,e{sup +}{nu}{sub e}){sup 4}He capture reactions at thermal neutron and keV proton energies have been calculated with the Variational Monte Carlo method. The ground state and low-energy continuum wave functions have been determined variationally from a realistic Hamiltonian, and include both nucleon and {Delta}-isobar degrees of freedom. The electroweak transition operator contains one- and two-body components in the N + {Delta} Hilbert space.

  2. Effects of. Delta. -isobar degrees of freedom on the reactions sup 3 He(n,. gamma. ) sup 4 He and sup 3 He(p,e sup +. nu. sub e ) sup 4 He at low-energy

    Energy Technology Data Exchange (ETDEWEB)

    Schiavilla, R.

    1991-01-01

    The cross sections of the radiative {sup 3}He(n,{gamma}){sup 4}He and weak {sup 3}He(p,e{sup +}{nu}{sub e}){sup 4}He capture reactions at thermal neutron and keV proton energies have been calculated with the Variational Monte Carlo method. The ground state and low-energy continuum wave functions have been determined variationally from a realistic Hamiltonian, and include both nucleon and {Delta}-isobar degrees of freedom. The electroweak transition operator contains one- and two-body components in the N + {Delta} Hilbert space.

  3. Geometrical aspects of reaction cross sections for 3He, 4He and 12C projectiles

    International Nuclear Information System (INIS)

    Ingemarsson, A.; Lantz, M.

    2003-04-01

    A black-disc model combined with accurate matter densities has been used for an investigation of reaction cross sections for 3 He, 4 He and 12 C projectiles. A simple relation is derived between the energy dependence of the reaction cross sections and the strength of the nucleon-nucleon interaction. A comparison is also made of the reaction cross sections for 3 He and 4 He for six different nuclei 12 C, 16 O, 40 Ca, 58,60 Ni and 208 Pb

  4. Primary populations of metastable antiprotonic $^{4}He$ and $^{3}He$ atoms

    CERN Document Server

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

    2002-01-01

    Initial population distributions of metastable antiprotonic **4He and **3He atoms over principal and angular momentum quantum numbers were investigated using laser spectroscopy. The total fractions of antiprotons captured into the metastable states of the atoms were deduced. Cascade calculations were performed using the measure populations to reproduce the delayed annihilation time spectrum. Results showed agreement between the simulated and measured spectra. (Edited abstract) 30 Refs.

  5. Anomalous Quasiparticle Reflection from the Surface of a ^{3}He-^{4}He Dilute Solution.

    Science.gov (United States)

    Ikegami, Hiroki; Kim, Kitak; Sato, Daisuke; Kono, Kimitoshi; Choi, Hyoungsoon; Monarkha, Yuriy P

    2017-11-10

    A free surface of a dilute ^{3}He-^{4}He liquid mixture is a unique system where two Fermi liquids with distinct dimensions coexist: a three-dimensional (3D) ^{3}He Fermi liquid in the bulk and a two-dimensional (2D) ^{3}He Fermi liquid at the surface. To investigate a novel effect generated by the interaction between the two Fermi liquids, the mobility of a Wigner crystal of electrons formed on the free surface of the mixture is studied. An anomalous enhancement of the mobility, compared with the case where the 3D and 2D systems do not interact with each other, is observed. The enhancement is explained by the nontrivial reflection of 3D quasiparticles from the surface covered with the 2D ^{3}He system.

  6. Cosmogenic 3He in detrital gold

    Science.gov (United States)

    Stuart, Finlay; Yakubovich, Olga; Caracedo, Ana; Nesterenok, Alexander

    2017-04-01

    Since the measurement of cosmogenic He in an alluvial diamond by McConville and Reynolds (1996) the application of cosmogenic noble gases to individual detrital grains to quantify surface processes has not been vigorously pursued. The likely low rate of diffusion of cosmogenic He in native metals, and their resistance to weathering and disintegration during erosion and transport, makes them a potential record of long-term Earth surface processes. In an effort to assess the extent that detrital refractory metals record the exposure history during transport and storage we have undertaken a reconnaissance study of the He isotope composition in 18 grains (2-200 mg) of native gold, copper, silver, and PtPd, Pt3Fe and OsIr alloys from alluvial placer deposits from around the world. 4He is dominantly the result of U and Th decay within the grains, or decay of 190Pt in the Pt-rich alloys. 3He is measurable in 13 grains, concentrations range up to 2.7E+6 atoms/g. 3He/4He are always in excess of the crustal radiogenic ratio, up to 306 Ra. Although nucleogenic 3He produced by (n,α) reactions on 6Li, and 3He from trapped hydrothermal fluids, are present, the majority of the 3He is cosmogenic in origin. Using newly calculated cosmogenic 3He production rates in heavy metals, and a determination of the effect of implantation based on the stopping distances of spallogenic 3He and 3H, the grains have 3Hecos concentrations that are equivalent to 0.35 to 1.5 Ma exposure at Earth's surface. In a study of detrital gold grains from several sites in Scotland we have found that 10 % have 3He concentrations that are significantly in excess of that generated since the Last Glacial Maximum. These studies demonstrate that, with refinement, cosmogenic 3He in refractory detrital minerals can be used to quantify sediment transport and storage on the 1-10 Ma timescale. P. McConville & J.H. Reynolds (1989). Geochim. Cosmochim. Acta, 53, 2365-75.

  7. 186Os and 187Os enrichments and high-3He/4He sources in the Earth's mantle

    DEFF Research Database (Denmark)

    Brandon, A.D.; Graham, D.W.; Waight, Tod Earle

    2007-01-01

    at present remains core-mantle interaction. While some plumes with high 3He/4He, such as Hawaii, appear to have been subjected to detectable addition of Os (and possibly He) from the outer core, others such as Iceland do not. A positive correlation between 187Os/188Os and 3He/4He from 9.6 to 19 Ra in Iceland...

  8. 3He impurities on liquid 4He: possible existence of excited states

    International Nuclear Information System (INIS)

    Pavloff, N.; Treiner, J.

    1989-01-01

    We study, using a density functional approach, the properties of the two dimensional system formed by 3 He atoms on the surface of liquid 4 He, as a function of 3 He coverage N s . We find that the excited state recently proposed by Dalfovo and Stringari in the case of infinite dilution does survive when the number of surface 3 He atoms increases. For small values of N s , the surface tension σ is, as expected, linear in N s 2 . For N s ≅0.035 atom per square-Angstrom, i.e. half a monolayer, a new type of surface state starts being occupied, and this feature manifests itself by a change in the slope of σ as a function of N s 2 and, more clearly, by a discontinuity in the surface specific heat, which increases by a factor of almost 2. These predictions call for experimental investigations

  9. 3He/4He production ratios by tetrahedral symmetric condensation

    International Nuclear Information System (INIS)

    Takahashi, Akito

    2006-01-01

    The present paper treats application of the Electronic Quasi-Particle Expansion Theory (EQPET) model for Tetrahedral Symmetric Condensate (TSC) of H/D mixed systems for Pd host metal. Production ratios of 3 He/ 4 He for multi-body fusion reactions in H/D mixed TSC systems are calculated as a function of H/D mixing ratio. The model is further extended to treat direct nuclear interactions between host-metal nucleus and TSC of pure four protons (or four deuterons), since TSC can become very small (far less than 1 pm radius) charge-neutral pseudo-particle. Results for the case of Ni + 4p/TSC are discussed with Ni + p capture reactions and Ni + 4p fission reactions. (authors)

  10. Experimental Study of Photon Induced Reactions on 3He and 4He at Low Energies

    International Nuclear Information System (INIS)

    Tornow, W.

    2011-01-01

    Data are reported for the photodisintegration cross section of the reaction 3 He(γ, p) 2 H at ten energies between 7.0 and 16.0 MeV. Very preliminary data are presented for the reaction 4 He(γ, p) 3 H between 22.0 and 29.5 MeV in 0.5 MeV energy steps, and for the reaction 4 He(γ, n) 3 He at three energies around 28.0 MeV. High-pressure He/Xe gas scintillators served as target and detector. Our data are in better agreement with recent theoretical calculations than the majority of the existing data for all three reactions, but differ significantly from recent data taken with a mono-energetic photon beam and a time-projection chamber. (author)

  11. Overlap integrals of model wave functions of 4He and 3He,3H nuclei

    International Nuclear Information System (INIS)

    Voloshin, N.I.; Levshin, E.B.; Fursa, A.D.

    1990-01-01

    Overlap integrals of wave functions 4 He nucleus and 3 He and 3 H nuclei are calculated. Two types of model wave functions are used to describe the structure of nuclei. The wace function is taken as a product of the one-particle Gaussian functions of the Gaussian type in the second case

  12. Bulk damping of sound in superfluid 3He--4He under stagnation of the normal component

    International Nuclear Information System (INIS)

    Karchava, T.A.; Sanikidze, D.G.; Chkhaidze, N.D.

    1983-01-01

    The propagation of waves in superfluid 3 He-- 4 He solutions is considered under partial stagnation of the normal component. The wave processes in capillaries are presented as a superposition of the first sound, second sound, and viscous and diffusion waves. The damping coefficients are calculated for the modified first sound and for the thermal wave in superfluid 3 He-- 4 He solutions and related to the viscosity, thermal conductivity, diffusion, barodiffusion, and thermodiffusion coefficients

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

    Science.gov (United States)

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

    2015-03-01

    New helium isotope and trace-element abundance data are reported for pyroxenites and eclogites from South Africa, Siberia, and the Beni Bousera Massif, Morocco that are widely interpreted to form from recycled oceanic crustal protoliths. The first He isotope data are also presented for Archaean peridotites from the Kaapvaal (South Africa), Slave (Canada), and Siberian cratons, along with recently emplaced off-craton peridotite xenoliths from Kilbourne Hole, San Carlos (USA) and Vitim (Siberia), to complement existing 3He/4He values obtained for continental and oceanic peridotites. Helium isotope compositions of peridotite xenoliths vary from 7.3 to 9.6 RA in recently (volcanics that contain a contribution from asthenospheric sources. Using the new He isotope data for cratonic peridotites and assuming that significant portions (>50%) of the Archaean and Proterozoic continental lithospheric mantle are stable and unaffected by melt or fluid infiltration on geological timescales (>0.1 Ga), and that U and Th contents vary between cratonic lithosphere and non-cratonic lithosphere, calculations yield a 3He flux of 0.25-2.2 atoms/s/cm2 for the continental lithospheric mantle. These estimates differ by a factor of ten from non-cratonic lithospheric mantle and are closer to the observed 3He flux from the continents (<1 atoms/s/cm2). Pyroxenites and eclogites from the continental regions are all characterized by 3He/4He (0.03-5.6 RA) less than the depleted upper mantle, and relatively high U and Th contents. Together with oceanic and continental lithospheric peridotites, these materials represent reservoirs with low time-integrated 3He/(U + Th) in the mantle. Pyroxenites and eclogites are also characterized by higher Fe/Mg, more radiogenic Os-Pb isotope compositions, and more variable δ18O values (∼3‰ to 7‰), compared with peridotitic mantle. These xenoliths are widely interpreted to be the metamorphic/metasomatic equivalents of recycled oceanic crustal protoliths. The

  14. Specific features of kinetics of He3-He4 solid solution transformations at superlow temperatures

    International Nuclear Information System (INIS)

    Mikheev, V.A.; Majdanov, V.A.; Mikhin, N.P.

    1986-01-01

    The NMR data on the phase transition kinetics of 3 He- 4 He solid solutions at T=100 mK are considered. Studied are solid helium samples of a molecular volume of 20.55 cm 2 /mol with a 3 He content of 0.54 %. An unusually long phase transition time is found which is dependent on the prehistory of sample. The spin diffusion of 3 He in the transformated solution concentrated phase is found to be of a quasi-one-dimensional nature with the diffusion coefficient value typical of liquid

  15. Specific features of concentrated phase under decomposition of weak solid /sup 3/He-/sup 4/He solution

    Energy Technology Data Exchange (ETDEWEB)

    Mikheev, V A; Majdamov, V A; Kal' noj, S E; Omelaenko, N I

    1988-06-01

    The decomposition of solid /sup 3/He-/sup 4/He solutuions is studied on the samples 0.54% /sup 3/He(V=20.55 cm/sup 3//mole) and 0.60% /sup 4/He (V=24.04-24.93 cm/sup 3//mole) using pulse NMR method. At T=100 mK the decomposition of a weak solution proceeds more than for 30 h, the decomposition rate and temperature being dependent on the sample prehistory. In the concentrated phase of the decomposed weak solution the spin diffraction of /sup 3/He is of the quasi-one-dimensional character with the diffusion coefficient D /similar to/ 10/sup -5/ cm/sup 2//sec typical of liquid /sup 3/He and exceeding that bulk solid /sup 3/He by two orders of magnitude. The longitudinal relaxation time in the quasi-one-dimensional phase (/similar to/ 1 sec) is characteristic of the solid state and coinsides with data for bulk /sup 3/He. The temperature behaviour of magnetization in the quasi-one-dimensional phase is well described by the Curie law.

  16. Structure of the 8He exotic nucleus by the direct reactions 8He(p, p')8He, 8He(p,d)7He and 8He(p,t)6He

    International Nuclear Information System (INIS)

    Skaza, Flore

    2004-01-01

    The elastic and inelastic scattering of an 8 He beam on a proton target have been measured at GANIL. The first 8 He beam produced by the SPIRAL facility at an energy of 15.6 A.MeV impinged on a proton target. The experimental setup was composed by the eight telescopes MUST array dedicated to the measure of the light charged particles, by a scintillator plastic wall for the detection of heavy projectile, and by two beam tracking detectors CATS for the measure event by event of the incident position and angle of the beam on the target. This setup allowed also to measure the one and two neutron transfer reactions 8 He(p,d) 7 He and 8 He(p,t) 6 He. The excitation energy spectrum for 6,7,8 He and the angular distributions associated to each reaction have been measured. The observed excited states are in agreement with the data of the literature. We indicate the presence of a first excited state for 7 He at 0.9 MeV and we give for the first time the position of a second excited state in 8 He at 5.4 MeV; the presence of such state was just suggested in a previous experiment. CCBA calculations allowed to extract a spectroscopic factor of 4.4 ± 1.4 for the pick-up of one neutron from 8 He to 7 He. This value is in agreement with a closed p3/2 sub-shell for 8 He. To analyse the angular distributions for elastic and inelastic scattering, it was necessary to take into account in the formalism used to describe the reactions, via coupled channels reactions calculations, the couplings to the one neutron transfer reaction. (author) [fr

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

    Science.gov (United States)

    Fenton, C.; Pelletier, J.

    2005-12-01

    Several alluvial-fan terraces near Topock, AZ were created by successive entrenchment of Pliocene and Pleistocene alluvial-fan gravels shed from the adjacent Black Mountains along the lower Colorado River corridor below Hoover Dam. These fans interfinger with and overlie main-stem Colorado River sands and gravels and grade to terrace levels that correspond with pre-existing elevations of the Colorado River. Absolute dates for the ages of Quaternary deposits on the lower Colorado River are rare and cosmogenic 3He age estimates of these surfaces would help constrain the timing of aggradation and incision in the lower Colorado River corridor. We analyzed individual basalt boulders from several terrace surfaces for total 3He/4He concentrations to calculate cosmogenic 3He ages of each fan terrace; 3He/4He values, expressed as R/Ra where Ra is the 3He/4He of air, range from 0.29 to 590. Black Mountain volcanic rocks have reported K-Ar ages between 15 and 30 Ma and basalt samples from adjacent alluvial fans contain 0.42 to 47× 1012 at/g of 4He, which has likely accumulated due to nuclear processes. The amount of radiogenic 3He/4He can be significant in old rocks with young exposure ages and can complicate determination of cosmogenic 3 He content. Alpha-decay of U, Th, and their daughter isotopes produces large amounts of 4He, whereas significant amounts of radiogenic 3He are only produced through the neutron bombardment of Li and subsequent beta-decay of tritium. We measured Li, U, Th, major and rare-earth element concentrations in whole-rock basalts and mineral separates. These concentrations are used to estimate the ratio of radiogenic helium contributed to the total helium system in our samples. Li concentrations typically range from 6 to 17 ppm, with one outlier of 62 ppm. U contents range from calculations predict that the average radiogenic helium (R/Ra) contributed to the total helium in Black Mountain basalt samples is 0.011. Other noble gas studies have shown

  18. Calculations of static properties of spin-polarized 3He--4He mixtures

    International Nuclear Information System (INIS)

    Owers-Bradley, J.R.; Bowley, R.M.; Main, P.C.

    1985-01-01

    The theory of dilute mixtures of 3 He in 4 He that have been polarized by a strong magnetic field is developed. The interaction between the quasiparticles is taken to be constant, an approximation valid at low temperatures. The polarization of the mixture depends on the strength of the interaction. The internal energy, the specific heat, the osmotic pressure, and the velocity of second sound are also calculated. The specific heat is relatively insensitive to the interaction, but it does change significantly with magnetic field. The osmotic pressure is more sensitive to the effects of the interaction for some 3 He concentrations and temperatures. The velocity of second sound behaves qualitatively like the osmotic pressure. The measurement of these quantities as a function of temperature and magnetic field is discussed with a view to obtaining the strength of the interaction between quasiparticles

  19. 6 Ma age of carving Westernmost Grand Canyon: Reconciling geologic data with combined AFT, (U-Th)/He, and 4He/3He thermochronologic data

    Science.gov (United States)

    Winn, Carmen; Karlstrom, Karl E.; Shuster, David L.; Kelley, Shari; Fox, Matthew

    2017-09-01

    Conflicting hypotheses about the timing of carving of the Grand Canyon involve either a 70 Ma (;old;) or conflict with these lines of evidence, but are reconciled in this paper via the integration of three methods of analyses on the same sample: apatite (U-Th)/He ages (AHe), 4He/3He thermochronometry (4He/3He), and apatite fission-track ages and lengths (AFT). HeFTy software was used to generate time-temperature (t-T) paths that predict all new and published 4He/3He, AHe, and AFT data to within assumed uncertainties. These t-T paths show cooling from ∼100 °C to 40-60 °C in the Laramide (70-50 Ma), long-term residence at 40-60 °C in the mid-Tertiary (50-10 Ma), and cooling to near-surface temperatures after 10 Ma, and thus support young incision of the westernmost Grand Canyon. A subset of AHe data, when interpreted alone (i.e. without 4He/3He or AFT data), are better predicted by t-T paths that cool to surface temperatures during the Laramide, consistent with an ;old; Grand Canyon. However, the combined AFT, AHe, and 4He/3He analysis of a key sample from Separation Canyon can only be reconciled by a ;young; Canyon. Additional new AFT (5 samples) and AHe data (3 samples) in several locations along the canyon corridor also support a ;young; Canyon. This inconsistency, which mimics the overall controversy of the age of the Grand Canyon, is reconciled here by optimizing cooling paths so they are most consistent with multiple thermochronometers from the same rocks. To do this, we adjusted model parameters and uncertainties to account for uncertainty in the rate of radiation damage annealing in these apatites during sedimentary burial and the resulting variations in He retentivity. In westernmost Grand Canyon, peak burial conditions (temperature and duration) during the Laramide were likely insufficient to fully anneal radiation damage that accumulated during prolonged, near-surface residence since the Proterozoic. We conclude that application of multiple

  20. Experimental measurements of 3He and 4He mobility in olivine and clinopyroxene at magmatic temperatures

    Science.gov (United States)

    Trull, T. W.; Kurz, M. D.

    1993-03-01

    In-vacuo heating of 0.5 -0.7 mm olivine and clinopyroxene grains separated from Hawaiian ultramafic xenoliths leads to complete He loss within hours to days for temperatures of 700-1400°C. Diffusivities calculated from the observed release rates assuming spherical grains and initially homogeneous He distributions define Arrhenius relations with activation energies of 420 ± 20 and 290 ± 40 Kj/mol and log 10D0 of +5.1 ± .7 and +2.1 ± 1.2 cm 2/s in olivine and pyroxene, respectively. Values at 1350°C are 5.3 × 10 -9 cm 2/s in olivine and 10 times faster in pyroxene (4.7 × 10 -8 cm 2/s). These values include small corrections for grain size variations and, in the case of olivine, about 15% prior diffusive He loss. However, an important factor that has not been considered in previous studies of this type, is that the xenolith He resides predominantly within CO 2 rich fluid inclusions. Theoretical description of He loss in such a case demonstrates that the diffusivities calculated using the standard approach actually represent the product of the true volume diffusivity ( D) and the helium solubility, as represented by the distribution coefficient KDv (defined by C crystal/C fluid). Although He solubility in crystals is not well determined, estimates based on the CO 2 concentrations in these samples suggest that it is very low ( KDv of 3 × 10 -4 for pyroxene and 6 × 10 -6 for olivine; which also implies low crystal-melt distribution coefficients of .05 and .001). The resultant corrected diffusion rates are significantly faster than those obtained by the standard approach (~ 10 -4 cm 2/s at 1350°C and are thus higher than basaltic melt values). The most reasonable interpretation of this result is that He release is enhanced by internal grain fractures, including the planar healed cracks along which most fluid inclusions are arrayed. This treatment illustrates the difficulties involved in extrapolating laboratory He release measurements to nature, in particular

  1. Possibility of a 4He2 bound state, effective range theory, and very low energy He--He scattering

    International Nuclear Information System (INIS)

    Uang, Y.; Stwalley, W.C.

    1982-01-01

    The best available intermolecular potential for helium by Aziz, Nain, Carley, Taylor, and McConville is shown here for the first time to have a 4 He 2 bound state. Two numerical analyses, namely, eigenvalue solution and effective range theory, are used to support this conclusion. Unlike usual chemically bound species, the binding energy of this very weakly bound level is found to be only 8.3 x 10 -4 K, which is four orders of magnitude smaller than the potential well depth epsilon = 10.8 K. The scattering length for He+He collisions, determined from effective range theory, is used to calculate the elastic cross section in the very low energy limit. The results (1.878 x 10 5 A 2 for 4 He+ 4 He and 6.035 x 10 2 A for 3 He+ 3 He) are consistent with measurements at the lowest velocities yet attained. In terms of the estimated uncertainties of the parameters of the potential of Aziz and co-workers, it is shown that it is very likely that a bound state of the 4 He 2 molecule does in fact exist

  2. Study of the {sup 6}Li + p → {sup 3}He + {sup 4}He reaction in inverse kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Betsou, C.; Pakou, A.; Aslanoglou, X.; Nicolis, N.G.; Sgouros, O.; Soukeras, V. [The University of Ioannina, Department of Physics and HINP, Ioannina (Greece); Cappuzzello, F. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Universita di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Acosta, L. [Universidad Nacional Autonoma de Mexico, Instituto de Fisica, Mexico Distrito Federal (Mexico); INFN, Catania (Italy); Agodi, C.; Carbone, D.; Cavallaro, M.; Di Pietro, A.; Fernandez-Garcia, J.P.; Figuera, P.; Fisichella, M. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Foti, A. [Universita di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); INFN, Catania (Italy); Keeley, N. [National Centre for Nuclear Research, Otwock (Poland); Marquinez-Duran, G.; Martel, I. [Universidad de Huelva, Departamento de Fisica Aplicada, Huelva (Spain); Mazzocco, M.; Strano, E.; Torresi, D. [Universita di Padova, Departimento di Fisica e Astronomia, Padova (Italy); INFN, Padova (Italy); Pierroutsakou, D. [INFN, Napoli (Italy); Rusek, K. [University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland); Stiliaris, E. [University of Athens, Institute of Accelerating Systems and Applications and Department of Physics, Athens (Greece)

    2015-07-15

    Angular distribution measurements were performed for the {sup 6}Li + p → {sup 3}He + {sup 4}He reaction in inverse kinematics at incident energies of 2.7, 3.3, 4.2 and 4.8 MeV/u. The detection of both recoils ({sup 3}He and {sup 4}He) over the laboratory angle range θ{sub lab} = 16 {sup circle} to 34 {sup circle} allowed the determination of the angular distribution over a wide angular range in the center-of-mass frame (θ{sub c.m.} ∝ 40 {sup circle} to 140 {sup circle}). The results clarify inconsistencies between existing data sets and are consistent with compound nucleus model calculations. (orig.)

  3. Apparent violation of isospin symmetry in the 3H(3He,2H)4He reaction

    International Nuclear Information System (INIS)

    Rai, G.; Blyth, C.O.; England, J.B.A.; Farooq, A.; Karban, O.; Rawas, E.; Roman, S.; Vlastou, R.

    1988-01-01

    Angular distributions of the vector analyzing powers for the 3 H( 3 He, 2 H) 4 He reaction have been measured over the incident energy range 18--33 MeV. The measurements centered about 18 MeV display a deviation from the antisymmetric shape expected from isospin symmetry. Concentrating on the explanation of the 90 0 analyzing powers, we report the results of a distorted-wave Born approximation (DWBA) analysis which includes the direct and exchange processes and the spin-orbit potential. It is shown that the anomalous behavior of the 90 0 vector analyzing powers can be largely explained by the effect of a single F-wave potential resonance which leads to the magnification of the short-range differences between the 3 He and 3 H wave functions

  4. Lowest vibrational states of 4He3He+: Non-Born-Oppenheimer calculations

    International Nuclear Information System (INIS)

    Stanke, Monika; Bubin, Sergiy; Kedziera, Dariusz; Molski, Marcin; Adamowicz, Ludwik

    2007-01-01

    Very accurate quantum mechanical calculations of the first five vibrational states of the 4 He 3 He + molecular ion are reported. The calculations have been performed explicitly including the coupling of the electronic and nuclear motions [i.e., without assuming the Born-Oppenheimer (BO) approximation]. The nonrelativistic non-BO wave functions were used to calculate the α 2 relativistic mass velocity, Darwin, and spin-spin interaction corrections. For the lowest vibrational transition, whose experimental energy is established with high precision, the calculated and the experimental results differ by only 0.16 cm -1

  5. Geometrical aspects of reaction cross sections for {sup 3}He, {sup 4}He and {sup 12}C projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Ingemarsson, A. [Uppsala Univ. (Sweden). Dept. of Radiation Sciences; Lantz, M. [Uppsala Univ. (Sweden). The Svedberg Laboratory

    2003-04-01

    A black-disc model combined with accurate matter densities has been used for an investigation of reaction cross sections for {sup 3}He, {sup 4}He and {sup 12}C projectiles. A simple relation is derived between the energy dependence of the reaction cross sections and the strength of the nucleon-nucleon interaction. A comparison is also made of the reaction cross sections for {sup 3}He and {sup 4}He for six different nuclei {sup 12}C, {sup 16}O, {sup 40}Ca, {sup 58,60}Ni and {sup 208}Pb.

  6. Quenching of 4He(21S,21P) and 3He(21S,21P) states by collisions with Ne(1S0) atoms

    International Nuclear Information System (INIS)

    Blagoev, K.B.; Dimova, E.; Petrov, G.M.

    2004-01-01

    The cross sections and rate constants for quenching 4 He(2 1 S), 4 He(2 1 P), 3 He(2 1 S) and 3 He(2 1 P) states by collisions with ground state Ne atoms are measured by a time-resolved method in a He-Ne electron beam excited plasma at low pressure. These rate constants at T g =600 K are: k 4 He(2 1 S) =(1.6±0.2)x10 -10 , k 4 He(2 1 P) =(3.4±2.5)x10 -10 , k 3 He(2 1 S) =(1.6±0.2)x10 -10 and k 3 He(2 1 P) =(5.7±1.2)x10 -10 cm 3 s -1 . The cross sections derived from the rate constant are σ 4 He(2 1 S) =(8.4±0.8)x10 -16 , σ 4 He(2 1 P) =(1.8±1.3)x10 -15 , σ 3 He(2 1 S) =(7.1±0.9)x10 -16 and σ 3 He(2 1 P) =(2.6±0.5)x10 -15 cm 2 , respectively. The diffusion coefficient of 3 He(2 1 S) in 3 He is estimated to be D 3 He(2 1 S)- 3 He =1.9D 4 He(2 1 S)- 4 He , based on comparison with 4 He. A time-dependent collisional radiative model for an e-beam sustained He-Ne plasma is developed and the predicted line intensity of NeI λ=6328 A line is compared with the experimental data. The influence of different processes involved in population and depopulation dynamics of He(2 1 S) state are evaluated

  7. Specific features of kinetics of He/sup 3/-He/sup 4/ solid solution transformations at superlow temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mikheev, V A; Majdanov, V A; Mikhin, N P

    1986-06-01

    The NMR data on the phase transition kinetics of /sup 3/He-/sup 4/He solid solutions at T=100 mK are considered. Studied are solid helium samples of a molecular volume of 20.55 cm/sup 2//mol with a /sup 3/He content of 0.54%. An unusually long phase transition time is found which is dependent on the prehistory of sample. The spin diffusion of /sup 3/He in the transformated solution concentrated phase is found to be of a quasi-one-dimensional nature with the diffusion coefficient value typical of liquid.

  8. One-body density matrix and the momentum density in 4He and 3He

    International Nuclear Information System (INIS)

    Whitlock, P.A.; Panoff, R.M.

    1984-01-01

    The one-body density matrix and the momentum density for liquid and solid 4 He, determined from Green's Function Monte Carlo calculations using the HFDHE2 pair potential, are described. Values for the condensate fraction and the kinetic energy derived from these calculations are given and compared to recent experimental results. Preliminary results from variational Monte Carlo calculations on n(r) and n(k) for liquid 3 He are also reported

  9. Quasi-free and sequential processes in the 9Be(3He,αα)4He reaction at 2,8 MeV

    International Nuclear Information System (INIS)

    Barbarino, S.; Lattuada, M.; Riggi, F.; Spitaleri, C.; Vinciguerra, D.

    1979-01-01

    The quasi-free contribution to the 9 Be( 3 He,αα) 4 He reaction at low incident energy is studied under various detection configurations. The measurements performed at quasi-free angles (symmetrical and non-symmetrical configurations) furter confirm that a large region in the energy spectra is dominated by the quasi-free 5 He( 3 He,α) 4 He process. From a comparison of these results with those taken at symmetrical angles where the minimum accepted momentum of the spectator is around 70 MeV/c, the conclusion is drawn that no significant distortion is introduced by the sequential peak tails in the deduced 5 He- 4 He momentum distribution

  10. Second sound, osmotic pressure, and Fermi-liquid parameters in 3He-4He solutions

    International Nuclear Information System (INIS)

    Corruccini, L.R.

    1984-01-01

    Second-sound velocities and osmotic pressures are analyzed to obtain the first experimental values for the Landau compressibility parameter F 0 /sup s/ in 3 He- 4 He solutions. Data are presented as a function of pressure and 3 He concentration, and are compared to theoretical predictions. The square of the second-sound velocity at finite temperature is found to be accurately proportional to the internal energy of a perfect Fermi gas. Using inertial effective masses given by the Landau-Pomeranchuk theory, the square of the velocity is found to separate into two parts: a temperature-dependent part characterized completely by ideal Fermi-gas behavior and a temperature-independent part containing all the Fermi-liquid corrections. This is related to a similar separation found in the osmotic pressure

  11. The search for high-energy deuterons in the 3He +3He reaction

    International Nuclear Information System (INIS)

    Pigeon, R.; Slobodrian, R.J.

    1979-01-01

    High-energy deuterons have been detected from the 3 He + 3 He reaction with a system sensitive to cross-sections of 0.6 nb sr -1 . Several tests have permitted to evaluate the small contribution of spurious events. The deuterons are kenematically consistent with the reaction 3 He + 3 He→ 2 H + 4 He + e + +ν, but the measured cross-section at 20deg laboratory is too high for a weak-interaction process; (1.3 +- 0.2) nb sr -1 . It might be due to an interaction of intermediate strength causing the decay of pp pairs ( 3 He) into deuterons. Other alternatives and the implications concerning fusion processes and the production of neutrinos in the sun are discussed in the text

  12. 3He/4He ratio, noble gas abundance and K-Ar dating of diamonds - an attempt to search for the records of early terrestrial history

    International Nuclear Information System (INIS)

    Ozima, M.; Zashu, S.; Nitoh, O.

    1983-01-01

    The 3 He/ 4 He ratios measured in 27 Southern Africa diamond stones, four from Premier Mine and the rest of unidentified origin, range from 4.2 x 10 -8 to 3.2 x 10 -4 , with three stones above 1 x 10 -4 . We conclude that the initial helium isotopic ratio ( 3 He/ 4 He) 0 in the earth was significantly higher than that of the planetary helium-A ( 3 He/ 4 He = 1.42 x 10 -4 ), but close to the solar helium ( 3 He/ 4 He = approx. 4 x 10 -4 ). The apparent K-Ar ages for the twelve diamonds of unidentified origin show enormously old age, indicating excess argon-40. 3 He/ 4 He evolution in diamonds suggests that the diamonds with the high 3 He/ 4 He ratio (> 2 x 10 -4 ) may be as old as the earth. Noble gas elemental abundance in the diamonds relative to the air noble gas abundance shows monotonic decrease with a decreasing mass number. This paper discusses the implications of these observations on the early solar system and the origin of diamonds. (author)

  13. The relation between temperature and concentration gradients in superfluid sup 3 He- sup 4 He solutions

    CERN Document Server

    Zadorozhko, A A; Rudavskij, E Y; Chagovets, V K; Sheshin, G A

    2003-01-01

    The temperature and concentration gradients nabla T and nabla x in a superfluid sup 3 He- sup 4 He mixture with an initial concentration 9,8 % of sup 3 He are measured in a temperature range 70-500 mK. The gradients are produced by a steady thermal flow with heating from below. It is shown that the value of nabla x/nabla T observed in the experiment is in good agreement with the theoretical model derived from the temperature and concentration dependences of osmotic pressure. The experimental data permitted us to obtain a thermal diffusion ratio of the solution responsible for the thermal diffusion coefficient.

  14. Slowing-down of heavy ions in a fusible D-3He mixture

    International Nuclear Information System (INIS)

    Cocu, Francis; Uzureau, Jose; Lachkar, Jean.

    1982-01-01

    First experimental results connected with the study of the slowing-down of heavy ions ( 16 O, 63 Cu, 109 Ag) at energies of approximately 1 MeV/A in a fusible mixture of D- 3 He indicate that the higher is the projectile mass the greater is the fusion reaction rate [fr

  15. Ab initio calculations of 3H(d,n)4He fusion

    International Nuclear Information System (INIS)

    Navratil, Petr; Quaglioni, Sofia

    2012-01-01

    We build a new ab initio many-body approach capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group method with the ab initio no-core shell model. In this way, we complement a microscopic-cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters. We will present the first results of the d- 3 H and d- 3 He fusion calculation obtained within our ab initio approach. We will also discuss our d- 4 He, 3 H- 4 He and 3 H- 3 H scattering calculations and the outline of the extension of the formalism to include three-cluster final states with the goal to calculate the 3 H( 3 H,2n) 4 He cross section

  16. Theoretical charge-exchange total cross sections for B+3 + He and C+4 + He collisions

    International Nuclear Information System (INIS)

    Shipsey, E.J.; Browne, J.C.; Olson, R.E.

    1977-01-01

    Charge-exchange total cross sections for the B +3 + He and C +4 + He systems have been calculated in the velocity range v = (1--10) x 10 7 cm/sec. Ab initio potential-energy curves and coupling-matrix elements were computed and employed in the impact-parameter classical-coupled equations that describe the collision to obtain the cross sections. For the B +3 + He system, our calculations are in excellent agreement with experimental results with the finding that the single-electron-transfer cross section rises rapidly to a maximum of 1.45 x 10 -15 cm 2 at v = 5.5 x 10 7 cm/sec. For the C +4 + He system, however, we find that the double-electron-transfer process is more important than the single-electron-transfer process. For example, at v = 5 x 10 7 cm/sec, the double-electron-transfer cross section is found to be 0.6 x 10 -16 cm 2 vs 5.5 x 10 -17 for the single-electron transfer. This is in disagreement with an experiment of Crandall which gave the single-charge-transfer process as dominant. However, the more recent experiment reported by Crandall, Olson, Browne, and Shipsey verifies the double charge transfer as the dominant process for low energies

  17. Dimension effect in impuriton gas of 3He -4He superfluid mixture

    International Nuclear Information System (INIS)

    Adamenko, I.N.; Bortnik, L.N.; Chervanev, A.I.

    1999-01-01

    The flow of quasiparticle gas forced by the gradients of thermodynamical values in the volume filled with a powder is considered. The exact solution of the kinetic equation is obtained. It is expressed in terms of matrix elements of the collision integral and partial scattering cross-sections of quasiparticles at the powder. The condition describing the steady non-equilibrium state of the quasiparticles gas in the volume filled with a porous material is obtained. The results obtained are valid for arbitrary relations of frequencies of quasiparticle-quasiparticle and quasiparticle-powder collisions. The transitions from the Knudsen regime of quasiparticle gas flow to the hydrodynamic one is investigated. The Knudsen effect in degenerated quantum gas is studied. The steady non-equilibrium state of 3 He- 4 He superfluid mixture impuriton gas is studied in confined geometry

  18. Analyzing Power of 3He(n, n)3He Between 1.60 and 5.54 MeV

    International Nuclear Information System (INIS)

    Esterline, J.; Tornow, W.

    2013-01-01

    We report the measurements of the analyzing power A y (θ) of n- 3 He elastic scattering with unprecedented accuracy and angular coverage at five incident neutron energies between 1.60 and 5.54 MeV. To this end, we employed the polarization-transfer reactions 3 H(p, n) 3 He and 2 H(d, n) 3 He at 0 ° for neutron generation and a recently developed high-pressure 3 He gas scintillator as an active target, enabling neutron-time-of-flight and 3 He recoil-energy determinations. We obtained simultaneously the neutron polarization with a 4 He-based polarimeter, capitalizing on the well-known n- 4 He A y (θ). Our n- 3 He A y (θ) data are compared to rigorous four-nucleon calculations using high-precision nucleon–nucleon potential models. The agreement between data and calculations is fair at the lower energies and becomes less satisfactory with increasing neutron energy. However, in comparison to the pure isotriplet p- 3 He system in the same energy region, the agreement between measured and calculated A y is much better for the mixed (isotriplet and isosinglet) n- 3 He system, indicating large and somewhat counterintuitive isospin effects. We note that the incorporation of a Δ-mediated three-nucleon force in calculations of n- 3 He scattering was found to affect A y (θ) negligibly, suggesting the need for the reconsideration of fundamental interactions in resolving the four-nucleon analyzing power puzzle first established about a decade ago in p- 3 He scattering. (author)

  19. An apparatus for preparing isotopically pure He4

    International Nuclear Information System (INIS)

    McClintock, P.V.E.

    1978-01-01

    A cryostat has been constructed for extracting pure He 4 from He II of natural isotopic composition by means of a heat flush technique. It is shown that the method is in principle capable of yielding He 4 which is entirely devoid of He 3 isotopic impurities. A secondary heat flush, operated in conjunction with a conical heat exchanger of novel design, was used to place an experimental lower bound of 2 x 10 15 on the He 4 /He 3 ratio of the product, a standard sufficient for all present or projected applications requiring isotopically pure He 4 . The apparatus produces 2 000 1 (at standard temperature and pressure) of He 4 per thermal cycle. The design of future purifiers is discussed. (author)

  20. Is e+e- pair emission important in the determination of the 3He+4He S factor?

    Science.gov (United States)

    Snover, K. A.; Hurd, A. E.

    2003-05-01

    We show that the cross section for direct E0 pair emission is related to the cross section for direct E2 photon emission, and is a negligible contribution to the total capture cross section for 3He+4He→7Be. E0 resonance emission, E1 pair emission, and internal conversion are also negligible. Thus there cannot be significant contributions to the 3He+4He→7Be capture cross section at low energies from electromagnetic emission processes other than single photon emission.

  1. Spin-polarized electron capture for the Na+3He2+ system at a 3He2+ impact energy of 5.33--9.33 keV/amu

    International Nuclear Information System (INIS)

    Tanaka, M.; Shimakura, N.; Ohshima, T.; Katori, K.; Fujiwara, M.; Ogata, H.; Kondo, M.

    1994-01-01

    3 He + atomic polarizations following the spin-polarized electron capture process for the N rvec a(3s)+ 3 He 2+ system were measured at 3 He 2+ impact energies from 5.33 to 9.33 keV/amu. The magnitude of the 3 He + atomic polarizations was deduced from the 3 He + nuclear polarization measured by means of beam-foil spectroscopy. The observed polarization transfer coefficient P T defined by the ratio of the 3 He + atomic polarization to the sodium one showed a pronounced reduction from unity, which was qualitatively explained by the prediction of a simple cascade photon decay model. Evidence for a further reduction of P T from the above model and a possible impact energy dependence of P T suggested an excessive depolarization due to the presence of the collision alignment parameter A 0 col of 3 He + formed by the electron capture process. In order to see this more closely, the observed P T 's were examined theoretically using the semiclassical impact parameter method, in which an 18-state molecular expansion was employed, and atomic-type electron translation effects were rigorously taken into account. Ensuring that both the absolute values and the impact energy dependence of the observed capture cross sections were remarkably well reproduced by the calculations in which the states up to 4f in 3 He + were introduced, it was demonstrated that the calculated results for P T qualitatively reproduced not only the absolute values of the observed P T 's but also their gentle decrease with increasing impact energy. Production of nuclear polarizations resulting from the polarized electron capture processes between multicharged heavy ions and alkaline-earth-metal atoms is an example of one use of the future project of universal polarized heavy-ion sources

  2. Evidence for pion exchange currents in the analysis of the /sup 4/He(p,d)/sup 3/He reaction at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, J R; Rost, E; Smith, G R [Colorado Univ., Boulder (USA). Nuclear Physics Lab.

    1979-12-01

    Previous unsuccessful analyses of /sup 4/He(p,d)/sup 3/He at intermediate energies have employed densities based directly on the measured e/sup -/ + /sup 4/He elastic scattering. When the effects of pion exchange currents are removed, the resulting DWBA analysis is in qualitative agreement with the experimental data.

  3. Thermodynamics of dilute 3He-4He solid solutions with hcp structure

    Science.gov (United States)

    Chishko, K. A.

    2018-02-01

    To interpret the anomalies in heat capacity CV(T) and temperature-dependent pressure P(T) of solid hexagonal close-packed (hcp) 4He we exploit the model of hcp crystalline polytype with specific lattice degrees of freedom and describe the thermodynamics of impurity-free 4He solid as superposition of phononic and polytypic contributions. The hcp-based polytype is a stack of 2D basal atomic monolayers on triangular lattice packed with arbitrary long (up to infinity) spatial period along the hexagonal c axis perpendicular to the basal planes. It is a crystal with perfect ordering along the layers, but without microscopic translational symmetry in perpendicular direction (which remains, nevertheless, the rotational crystallographic axis of third order, so that the polytype can be considered as semidisordered system). Each atom of the hcp polytype has twelve crystallographic neighbors in both first and second coordination spheres at any arbitrary packing order. It is shown that the crystal of such structure behaves as anisotropic elastic medium with specific dispersion law of phonon excitations along c axis. The free energy and the heat capacity consist of two terms: one of them is a normal contribution [with CV(T) ˜ T3] from phonon excitations in an anisotropic lattice of hexagonal symmetry, and another term (an "excessive" heat) is a contribution resulted by packing entropy from quasi-one-dimensional system of 2D basal planes on triangular lattice stacked randomly along c axis without braking the closest pack between neighboring atomic layers. The excessive part of the free energy has been treated within 1D quasi-Ising (lattice gas) model using the transfer matrix approach. This model makes us possible to interpret successfully the thermodynamic anomaly (heat capacity peak in hcp 4He) observed experimentally.

  4. He I and He II spectra of 4-haloanilines

    Science.gov (United States)

    Sky, Jason L. D.; von Nagy-Felsobuki, Ellak I.

    1999-02-01

    The ultraviolet photoelectron spectra (UPS) of 4-haloanilines were recorded and interpreted using a composite-molecule model. Numbering from the valence orbitals, the sequence of the eight lowest ionization energies for 4-fluoroaniline is: π(5 a″)4-bromoaniline is: π(5 a″)< π(4 a″)< nN(16a')< nX(15 a')< π(3 a″)< σ(14 a')˜ σ(13 a')< π(2 a″) (where X=Cl and Br, respectively), whereas for 4-iodoaniline the assignment is: π(5 a″)< π(4 a″)< nI(16 a')< nN(15 a')˜ π(3 a″)< σ(14 a')< σ(13 a')< π(2 a″). Comparison of the He I and He II band intensities and ab initio calculations using the HF-6-31G** model confirm this assignment. Comparison of the linear correlation of the in-plane lone-pairs and Allred electronegativities for the halobenzenes and haloanilines also reinforce the assignment.

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  6. EVIDENCE FOR A COMMON ACCELERATION MECHANISM FOR ENRICHMENTS OF {sup 3}He AND HEAVY IONS IN IMPULSIVE SEP EVENTS

    Energy Technology Data Exchange (ETDEWEB)

    Mason, Glenn M. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Nitta, Nariaki V. [Lockheed Martin Advanced Technology Center, Dept/A021S, B/252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Wiedenbeck, Mark E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Innes, Davina E., E-mail: glenn.mason@jhuapl.edu, E-mail: nitta@lmsal.com, E-mail: mark.e.wiedenbeck@jpl.nasa.gov, E-mail: innes@mps.mpg.de [Max-Planck-Institut für Sonnensystemforschung, D-37077 Göttingen (Germany)

    2016-06-01

    We have surveyed the period 1997–2015 for a rare type of {sup 3}He-rich solar energetic particle (SEP) event, with enormously enhanced values of the S/O ratio, that differs from the majority of {sup 3}He-rich events, which show enhancements of heavy ions increasing smoothly with mass. Sixteen events were found, most of them small but with solar source characteristics similar to other {sup 3}He-rich SEP events. A single event on 2014 May 16 had higher intensities than the others, and curved Si and S spectra that crossed the O spectrum above ∼200 keV nucleon{sup −1}. Such crossings of heavy-ion spectra have never previously been reported. The dual enhancement of Si and S suggests that element Q / M ratio is critical to the enhancement since this pair of elements uniquely has very similar Q / M ratios over a wide range of temperatures. Besides {sup 3}He, Si, and S, in this same event the C, N, and Fe spectra also showed curved shape and enhanced abundances compared to O. The spectral similarities suggest that all have been produced from the same mechanism that enhances {sup 3}He. The enhancements are large only in the high-energy portion of the spectrum, and so affect only a small fraction of the ions. The observations suggest that the accelerated plasma was initially cool (∼0.4 MK) and was then heated to a few million kelvin to generate the preferred Q / M ratio in the range C–Fe. The temperature profile may be the distinct feature of these events that produces the unusual abundance signature.

  7. Observable off-shell effects and the Pauli principle in the reactions 4He+deuteron → 4He+deuteron and 4He+deuteron → 4He+neutron+proton

    International Nuclear Information System (INIS)

    Hahn, K.

    1983-01-01

    In the present thesis we have studied the system 4 He-neutron-proton. Starting from the microscopic three-cluster model of the resonating group method the Hamiltonian of the optical fish-bone model is defined for the three cluster centers which contains effects from the Pauli principle of the whole six-nucleon system. Beside this microscopically founded Hamiltonian a second, purely phenomenologically defined Hamiltonian is applied, which is only fixed by the phase shifts of the systems neutron-proton and 4 He-nucleon. Both Hamiltonians are phase equivalent in the subsystems, i.e. the scattering waves of the subsystems differ only in the near-range. A comparison of the three-particle scattering observables of both approaches at the incident energies Esub(d)sup(lab) = 7.5 and 12 MeV shows surprisingly strong off-shell effects in the system 4 He-neutron-proton, the order of magnitude of which exceeds both in the elastic and in the breakup case widely the experimental measurement uncertainty. It means that in our system the near-range of the subsystem scattering waves and by this the kind of the reduction of the six-nucleon problem to a three-body problem play an important role. Furthermore we can in the case of the elastic reaction 4 He + deuteron -> 4 He + deuteron for the differential cross sections and the spherical analyzing powers in angular ranges, where the neglected Coulomb interaction should have only little influence, prove, that the microscopically foundes Hamiltonian leads to results which are more realistic than in the case of the phenomenological model. (orig./HSI) [de

  8. 4He(γ,dd and 3He(γ,pd reactions in nonlocal covariant model

    Directory of Open Access Journals (Sweden)

    Kasatkin Yu. A.

    2014-03-01

    Full Text Available Photonuclear reaction research is of great interest to obtain information about the structure of nuclei. The investigation of structural effects requires certain insights into the reaction mechanisms, that have to be identified on the basis of the fundamental principles of covariance and gauge invariance. The major achievement of the chosen model is the ability to reproduce the cross-section dependence using the minimal necessary set of parameters. We analyze the two-particle disintegration of 3He nuclei by photons. Our interest was raised by the fact that 3He is the simplest many-particle system which admits an exact solutions. We also consider the process 4He(γ, dd. This process comes at the expense of the quadrupole absorption of γ-rays, while the dipole transition is suppressed. This property is a consequence of the isospin selection as well as the identity of the particles in the final state. Obtained results describe the energy range from threshold (20 MeV to 140 MeV. Therefore, the model mentioned in the paper has the peculiarity to be valid not only for the low-energy regime, but also for higher energies. Present paper is devoted to determine the roles of different reaction mechanisms and to solve problems above.

  9. Two-parameter study of the quasiperiodic route to chaos in convecting 3He--superfluid-4He mixtures

    International Nuclear Information System (INIS)

    Mainieri, R.; Sullivan, T.S.; Ecke, R.E.

    1989-01-01

    We study the frequency lockings of two intrinsic hydrodynamic modes of a convecting 3 He-superfluid- 4 He mixture by independently varying the Rayleigh and Prandtl numbers. We establish points on the critical line in this parameter space using a transient technique to locate the spiral-node transition in the interior of three resonance horns. Universal scaling is demonstrated at winding numbers with golden mean tails by computing the f(α) singularity spectrum

  10. Contactless friction and the {sup 3}He-{sup 4}He dimer. Studies with the atomic-beam spin-echo spectrometer; Kontaktlose Reibung und das {sup 3}He-{sup 4}He-Dimer. Untersuchungen mit dem Atomstrahlspinechospektrometer

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Matthias

    2016-04-20

    In this thesis the time of flight resolved atomic beam spin echo method (SEToF) is applied to a {sup 3}He-beam for the first time and studied systematically. This method is shown to be superior to the usual atomic beam spin echo technique. With SEToF it is possible to almost completely remove unpolarized background and to reach a beam polarisation close to 100%. The SEToF technique is shown to be crucial for the first experimental proof of the existence of the {sup 3}He-{sup 4}He dimer. This dimer is the weakest bound van-der-Waals-molecule known to date. Furthermore, a drag force between an atom and a dielectric surface is detected originating from the fluctuating dipole moment of the atom. Not only the measured friction coefficients match their theoretical predictions perfectly, but our data also shows the correct temperature dependence. A great many technological renewals and improvements were installed in the apparatus during this thesis work. They have become necessary or sensible due to the relocation of the physics institute. A few of them are documented and motivated in this thesis.

  11. Measurements of the osmotic pressure in liquid mixtures of 3He and 4He near the lambda line and tricritical point

    International Nuclear Information System (INIS)

    Gearhart, C.A. Jr.

    1977-01-01

    Values of the concentration susceptibility (par. deltax/par. deltaΔ)/sub T,P/ near the lambda line and tricritical point in liquid mixtures of 3He and 4 He were calculated from measurements of osmotic pressure differences. Measurements were made by inducing a small 3 He mole fraction difference Δx between two chambrs separated by a pressure transducer, and measuring the resulting osmotic pressure difference as a function of temperature

  12. Galactic evolution of D and 3He including stellar production of 3He

    International Nuclear Information System (INIS)

    Dearborn, D.S.; Steigman, G.; Tosi, M.

    1996-01-01

    New stellar models which track the production and destruction of 3 He (and D) have been evolved for a range of stellar masses (0.65≤M/M circle-dot ≤100), metallicities (0.01≤Z/Z circle-dot ≤1), and initial (main-sequence) 3 He mass fractions (10 -5 ≤X 3,MS ≤10 -3 ). Armed with the 3 He yields from these stellar models we have followed the evolution of D and 3 He using a variety of chemical evolution models with and without infall of primordial or processed material. Production of new 3 He by the lower mass stars overwhelms any reasonable primordial contributions and leads to predicted abundances in the presolar nebula and/or the present interstellar medium in excess of the observationally inferred values. This result, which obtains even for zero primordial D and 3 He, and was anticipated by Rood, Steigman, ampersand Tinsley is insensitive to the choice of chemical evolution model; it is driven by the large 3 He yields from low-mass stars. In an attempt to ameliorate this problem we have considered a number of nonstandard models in which the yields from low-mass stars have been modified. Although several of these nonstandard models may be consistent with the 3 He data, they may be inconsistent with observations of 12 C/ 13 C, 18 O, and, most seriously the super- 3 He rich planetary nebulae. Even using the most extreme of these nonstandard models we obtain a generous upper bound to pregalactic 3 He:X 3P ≤3.2x10 -5 which, nonetheless, leads to a stringent lower bound to the universal density of nucleons. copyright 1996 The American Astronomical Society

  13. Application of {sup 14}N({sup 3}He,{sup 4}He){sup 13}N nuclear reaction to nitrogen profiling

    Energy Technology Data Exchange (ETDEWEB)

    Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1996-12-31

    In this paper the {sup 14}N({sup 3}He,{sup 4}He){sup 1`}3N reaction is proposed for nitrogen profiling in metals and other materials. The beam energy is chosen to be 4.65 MeV in order to use the high cross section. Two types of particle filtering are used: a 25 {mu}m thick mylar in front of the detector to avoid backscattered particle pileup and reduced detector bias voltage to avoid full energy detection of high energy protons produced by competing reactions. The depth resolution is about 150-200 nm and the sensitivity is better than for the {sup 14}N(d,{sup 4}He){sup 12}C reaction. The low level of neutron radiation background allows use of this reaction in accelerator laboratories without radiation shielding. 11 refs., 5 figs.

  14. Application of {sup 14}N({sup 3}He,{sup 4}He){sup 13}N nuclear reaction to nitrogen profiling

    Energy Technology Data Exchange (ETDEWEB)

    Wielunski, L S [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1997-12-31

    In this paper the {sup 14}N({sup 3}He,{sup 4}He){sup 1`}3N reaction is proposed for nitrogen profiling in metals and other materials. The beam energy is chosen to be 4.65 MeV in order to use the high cross section. Two types of particle filtering are used: a 25 {mu}m thick mylar in front of the detector to avoid backscattered particle pileup and reduced detector bias voltage to avoid full energy detection of high energy protons produced by competing reactions. The depth resolution is about 150-200 nm and the sensitivity is better than for the {sup 14}N(d,{sup 4}He){sup 12}C reaction. The low level of neutron radiation background allows use of this reaction in accelerator laboratories without radiation shielding. 11 refs., 5 figs.

  15. Inelastic electron scattering from 3He and 4He in the threshold region at high momentum transfer

    International Nuclear Information System (INIS)

    Rock, S.; Arnold, R.G.; Chertok, B.T.; Szalata, Z.M.; Day, D.; McCarthy, J.S.; Martin, F.; Mecking, B.A.; Sick, I.; Tamas, G.

    1981-01-01

    The cross section for inclusive inelastic electron scattering from the helium isotopes has been measured at momentum transfers squared of 0.8 less than or equal to Q 2 less than or equal to 5.0 (GeV/c) 2 for 3 He and 0.8 less than or equal to Q 2 less than or equal to 2.4 (GeV/c) 2 for 4 He. The data were taken at 10 0 and cover the range 1.0 2 /2M/sub He/ν, which includes the elastic peak, nuclear breakup threshold, the high momentum tail of the quasi elastic scattering, and pion production. The structure function, νW 2 , derived from the data is approaching a scaling limit at high Q 2 . It can be factored into a product of functions of Q 2 and of x as predicted by some models

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

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  17. Energy dependence of the 3He(3He,π+)6Li reaction

    International Nuclear Information System (INIS)

    Le Bornec, Y.; Hibou, F.; Bimbot, L.; Hennino, T.; Jourdain, J.C.; Reide, F.; Tatischeff, B.; Willis, N.; Aslanides, E.; Bergdolt, G.; Fassnacht, P.; Racca, C.; Boudard, A.; Bruge, G.; Lugol, J.C.

    1983-01-01

    The 3 He( 3 He, π + ) 6 Li reaction has been studied as a function of energy using the 3 He beam at SATURNE. Cross sections for the 6 Li ground state (1 + ) and 2.18 MeV (3 + ) levels have been obtained at 350, 420, 500 and 600 MeV incident energies at angles THETAsub(π)(lab)=15 0 and 40 0 . These results are compared with two theoretical predictions. (orig.)

  18. Manifestation of 12-quark bag state of 4He nucleus in elastic d4He scattering

    International Nuclear Information System (INIS)

    Mosallem, A.M.; Uzhinskij, V.V.

    2002-01-01

    The 4 He d elastic scattering at the momentum of 19.8 GeV/c is analyzed in the framework of the Glauber theory. The scattering amplitude was evaluated using different sets of values of the nucleon-nucleon amplitude parameters and the 4 He density function as a superposition of the Gaussian functions. It is shown that it is impossible to describe simultaneously the p 4 He and d 4 He elastic scattering cross sections using the same set of the NN-amplitude parameters. Inclusion of the twelve-quark bag admixture to the ground state of the 4 He nucleus in the calculations allows one to reproduce the experimental data quite well. It is shown that the admixture manifests itself in the d 4 He elastic scattering in the whole region of the momentum transfer. At small t the effect can be at the level of ∼ 10%. At large t it can be ∼30%

  19. The mechanism of 'solid-body' rotation of superfluid and normal components in the process of separation into layers of the over saturated 3He-4He solution

    International Nuclear Information System (INIS)

    Pashitskij, Eh.A.; Mal'nev, V.N.; Naryshkin, R.A.

    2005-01-01

    It is shown that unstable hydrodynamic vortices may be formed inside subcritical nuclei of separation in the normal component of the decaying over saturated 3 He- 4 He solution. We consider the mechanism of drag of the superfluid component of the 3 He- 4 He solution by the normal component into the 'solid-body' rotation due to the Hall-Vinen-Bekarevich-Khalatnikov forces in the equations of two-fluid hydrodynamics, resulting in the formation of quantized vortices. An increase in the average density of the quantized vortices may accelerate the process of heterogeneous decomposition of the 3 He- 4 He solution

  20. 4He-impurity effects on normal liquid 3He at low temperatures I - preliminary ideas and calculations

    International Nuclear Information System (INIS)

    Ghassib, H.B.; Chatterjee, S.

    1982-02-01

    The effects of 4 He impurities on the low-temperature properties of normal liquid 3 He are explored. It is argued that these effects should manifest themselves in, among other properties, the liquid structure factor at very low temperatures and momentum transfers, the acoustic impedance near the transition region from the zero- to the first-sound regime, the propagation of sound, the phase diagram, and the magnetic properties - including the magnetokinetic coefficients of the spin-polarized system. Several experiments are suggested to detect these macroscopic manifestations. (author)

  1. 3He impurity states on liquid 4He: From thin films to the bulk surface

    International Nuclear Information System (INIS)

    Pavloff, N.; Treiner, J.

    1991-01-01

    The structure of the states accessible to 3 He impurities in films of liquid 4 He on Nuclepore is investigated using a density functional approach with a finite-range effective interaction. In thick films, one finds that the two lowest states are localized in the surface region. For thinner films, the variation with film thickness of the first three states results from a delicate balance between the attractive tail of the substrate potential and the quantum finite-size effect. The existence of states localized in the second layer of the films is discussed. The energy difference between the ground state and the first excited state agrees with the recent determination of Higley, Sprague, and Hallock from magnetization measurements. The effective mass of the ground state has a structure similar to that obtained by Krotscheck and coworkers and exhibits a maximum for a 4 He coverage of 0.15 angstrom -2 , in agreement with the data of Gasparini and coworkers. A similar behavior is predicted for the effective mass of the first, second, and third excited states. The structure of the energy spectrum may also explain former results on third-sound measurements in thin mixture films by Laheurte et al. and by Hallock

  2. Juvenile helium in ancient rocks: II. U-He,K-Ar, Sm-Nd, and Rb-Sr systematics in the Monche Pluton. 3He/4He ratios frozen in uranium-free ultramafic rocks

    International Nuclear Information System (INIS)

    Tolstikhin, I.N.; Dokuchaeva, V.S.; Kamensky, I.L.; Amelin, Yu.V.

    1992-01-01

    The important geodynamic parameter, the 3 He/ 4 He ratio in rocks and fluids of the continental crust, is generally decreasing from the mantle values (≅ 10 -5 ) to the radiogenic ratio (≅ 10 -8 ) on the time scale of about 1 Ga or less. However, the ratios, observed in some ancient rocks and minerals, are much higher than the radiogenic value due to a preferential retention of trapped He, when compared with radiogenic helium and/or a low U/ 3 He ratio in a sample. The distribution of He, Ar, Nd, and Sr isotopes, K, Rb, Sm, and U in ultrabasic rocks, in rock-forming minerals, in ores from the 2.49 Ga Monche Pluton, and in basic rocks of the Main Range (the Kola Peninsula) enables one to distinguish sources of the rocks and trapped fluids and outline some peculiarities of petrogenetic and fluid processes. The initial values of var-epsilon Nd (T) = -0.9 ± 0.5 , 87 Sr/ 86 Sr(T) = 0.7021 ± 0.0002, for the 2.49 Ga Monche Pluton are rather similar to these for other layered intrusions of the Baltic Shield. They differ considerably from the model values for the depleted 2.5 Ga old mantle. The observed and rather different sources of 3 He and 4 He as well as the considerable constancy of their ratio in different minerals, separated from both the ultramafic rocks and gabbros, implies: (1) an intensive process of mixing between mantle and crustal components: a melt convection in the chamber may have occurred; (2) the two types of rocks could originate by crystallization differentiation of one and the same melt. Practically all 3 He and 4 He are concentrated in secondary amphiboles; hence the fluid which stimulated the metamorphic process was probably released from the ultramafite-bearing melt

  3. He3 cryostat

    International Nuclear Information System (INIS)

    Novichkova, L.G.; Kulikov, Yu.V.; Stashkova, N.M.

    1992-01-01

    An effective cryostat featuring a one-cycle He 3 refrigerator with a cryosorption pump is described. Gaseous He 3 in contained in a low-pressure vessel having a common wall with a liquid N 2 bath. Due to this, the gas is cooled before sorption and the sorption rate increases approximately by a factor of ten. The cryostat is provided with a needle valve which cuts off the ballast volume of the pipelines from the refrigerator. As a result, the pressure of He 3 vapours increases before condensation and with refrigerator dimensions selected properly, the liquefaction coefficient reaches approximately 80%. Test results of the cryostat and its specifications are presented. (Author)

  4. The cosmic-ray He-3/He-4 ratio from 200 MeV per nucleon(-1) to 3.7 GeV per nucleon(-1)

    DEFF Research Database (Denmark)

    Reimer, O.; Menn, W.; Hof, M.

    1998-01-01

    by their mass using the velocity versus magnetic rigidity technique. The measured He-3/He-4 ratios are corrected to the top of the atmosphere, and a comparison with previous data is given. The observed isotopic composition is found to be generally consistent with the predictions of a standard leaky box model...

  5. The breakdown of superfluidity in liquid 4He

    International Nuclear Information System (INIS)

    Nancolas, G.G.; McClintock, P.V.E.; Bowley, R.M.

    1985-01-01

    The rate upsilon at which negative ions nucleate charged vortex rings in a series of extremely dilute superfluid 3 He/ 4 He solutions has been measured at a pressure of 23 bar over a temperature range (T) 0.33 - 0.61K, electric field range (E) 1.0 x 10 4 - 1.5 x 10 6 Vm -1 and an isotopic ratio range (x) ( 3 H/ 4 He) = 2.1 x 10 -8 - 1.7 x 10 -7 . The results are presented. A model is proposed which accounts for the behaviour of upsilon(E,T) in terms of changes in the average occupancy by 3 He atoms of trapping states on the surface of the ion if the nucleation rate ν 1 , due to ions each having one trapped 3 He atom, is very much greater than ν 0 for bare ions. The nonlinearities in ν(x 3 ) are interpreted in terms of the simultaneous trapping of two (or more) 3 He atoms on a significant fraction of the ions. The model can be fitted closely to the experimental data, yielding numerical values of ν 1 , of the 3 He binding energy on the ion, and of a number of other relevant quantities. The addition of a 3 He atom to a bare ion affects its propensity to create vortex rings by reducing the critical velocity for the process and by increasing the rate constant. The implications of these results for microscopic theories of the vortex nucleation mechanism are discussed. (U.K.)

  6. Spectroscopy of the 6He,7He exotic nuclei with the Must2 telescopes and the Spiral beam of 8He

    International Nuclear Information System (INIS)

    Mougeot, X.

    2008-09-01

    The nuclear models have to be constrained using experimental data collected on weakly bound nuclei in order to improve their predictive power. The one and two neutron transfer reactions 8 He(p,d) 7 He and 8 He(p,t) 6 He were measured in inverse kinematics at GANIL. The 8 He beam, impinging on a proton target, was produced at 15.4 MeV/n by the SPIRAL facility. The experimental setup consisted of four MUST2 telescopes for the detection of the light charged particles, of one MUST2 telescope to identify the heavy projectile, and of two beam tracking detectors CATS to reconstruct the incident position and angle of the beam on the target. A complete analysis of the data taken with MUST2 was done for the first time. The performances of the detector were characterized, methods were developed for the calibrations and the selection of the events. The excitation energy spectra for 6,7 He and the angular distributions of the cross-sections were extracted. The resonant states of 6 He were observed at the following excitation energies: at 1.8 MeV (known), at 2.65(25) MeV with a width Γ = 1.6(4) MeV, and at 5.3(3) MeV, Γ = 2(1) MeV. One resonant state was observed for 7 He at 1.3(2) MeV, with a width Γ = 0.7(5) MeV. Our data do not exclude the controversial state at 0.9 MeV, Γ = 1 MeV. These results were obtained with the very good position and energy resolutions of MUST2. They are consistent with the calculations of the nuclear theories which include the treatment of the coupling to the continuum and the effects of the three-body interactions. (author)

  7. Designing an Epithermal Neutron Beam for Boron Neutron Capture Therapy for the Fusion Reactions 2H(d,n)3He and 3H(d,n)4He1

    International Nuclear Information System (INIS)

    Verbeke, J.M.; Costes, S.V.; Bleuel, D.; Vujic, J.; Leung, K.N.

    1998-01-01

    A beam shaping assembly has been designed to moderate high energy neutrons from the fusion reactions 2 H(d,N) 3 He and 3 H(d,n) 4 He for use fin boron neutron capture therapy. The low neutron yield of the 2 H(d,n) 3 He reaction led to unacceptably long treatment times. However, a 160 mA deuteron beam of energy 400 keV led to a treatment time of 120 minutes with the reaction 3 H(d,n) 4 He. Equivalent doses of 9.6 Gy-Eq and 21.9 Gy-Eq to the skin and to a 8 cm deep tumor respectively have been computed

  8. Energy spectrum of surface electrons over a {sup 3}He – {sup 4}He solution with a spatially non-uniform distribution of the light isotope

    Energy Technology Data Exchange (ETDEWEB)

    Bezsmolnyy, Ya.Yu.; Sokolova, E.S.; Sokolov, S.S. [B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Prospekt Nauky, 61103 Kharkov (Ukraine); Studart, Nelson [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Av. dos Estados, 5001, 09210-580 Santo André, São Paulo (Brazil); Departamento de Física, Universidade Federal de São Carlos, via Washington Luís, km 235, 13565-905 Säo Carlos, São Paulo (Brazil)

    2017-02-15

    The energy gap between the ground and first excited energy levels of surface electrons deposited over a dilute {sup 3}He - {sup 4}He solution is evaluated. Two spatial distributions of {sup 3}He atoms near the free surface solution are considered. One consists of a thin though macroscopic {sup 3}He film and in the other the {sup 3}He concentration varies continuously from the surface inside the liquid. The energy gap is calculated as a function of the parameters of the {sup 3}He spatial distribution for these distributions. It is shown that the energy gap dependence on the distribution parameters allows using measurements of intersubband transitions of the surface electrons to determine the {sup 3}He concentration distribution and, in principle, the nature of the spatial distribution of the light isotope near the surface of the solution.

  9. Probing HeII Reionization at z>3.5 with Resolved HeII Lyman Alpha Forest Spectra

    Science.gov (United States)

    Worseck, Gabor

    2017-08-01

    The advent of GALEX and COS have revolutionized our view of HeII reionization, the final major phase transition of the intergalactic medium. COS spectra of the HeII Lyman alpha forest have confirmed with high confidence the high HeII transmission that signifies the completion of HeII reionization at z 2.7. However, the handful of z>3.5 quasars observed to date show a set of HeII transmission 'spikes' and larger regions with non-zero transmission that suggest HeII reionization was well underway by z=4. This is in striking conflict with predictions from state-of-the-art radiative transfer simulations of a HeII reionization driven by bright quasars. Explaining these measurements may require either faint quasars or more exotic sources of hard photons at z>4, with concomitant implications for HI reionization. However, many of the observed spikes are unresolved in G140L spectra and are significantly impacted by Poisson noise. Current data cannot reliably probe the ionization state of helium at z>3.5.We request 41 orbits to obtain science-grade G130M spectra of the two UV-brightest HeII-transmitting QSOs at z>3.5 to confirm and resolve their HeII transmission spikes as an unequivocal test of early HeII reionization. These spectra are complemented by recently obtained data from 8m telescopes: (1) Echelle spectra of the coeval HI Lya forest to map the underlying density field that modulates the HeII absorption, and (2) Our dedicated survey for foreground QSOs that may source the HeII transmission. Our recent HST programs revealed the only two viable targets to resolve the z>3.5 HeII Lyman alpha forest, and to conclusively solve this riddle.

  10. Exchange currents in low-energy nucleon capture by 3He

    International Nuclear Information System (INIS)

    Wervelman, Rob.

    1991-01-01

    The studies described in this thesis concern absolute cross-section measurements of the radiative neutron capture reactions 3 He (n,γ) 4 He and 3 He(n,γγ) 4 He, and are complements with shell-model calculations on the radiative thermal neutron capture reaction by 3 He and on the weak 3 He(p,e + ν e ) 4 He reaction. The experiments have been performed at two neutron energies, with sub-thermal neutrons where s-wave capture is dominant, and with a quasi-monochromatic 24.5 keV neutron beam (p-wave capture). It has been found that the thermal neutron capture cross section of 3 He is 55±3 μb. Measured at 24.5 keV-neutron energy, the radiative capture cross section for p-wave neutrons turned out to be 9.1±0.8 μb. A measurement on the double-photon reaction 3 He(n th ,γγ) has yielded a cross-section value of 30±80 μb. In the theoretical part of the work a standard model of nuclear weak and electromagnetic interaction currents, consisting of a one-body impulse approximation and a two-body meson-exchange current part, has been applied to the process of nucleon capture by 3 He. Within the framework of a (0+2) (h/2π)ω shell-model calculation, using Sussex matrix elements for the 3 He and 4 He ground state wave functions, the empirical radiative cross sections for thermal neutrons of 3 He could be reproduced with satisfactory agreement. The total MEC correction to the radiative thermal neutron capture cross section is rather small because large cancellations occur between the various contributions. In the 3 He(p,e + ν e ) 4 He reaction meson-exchange contributions enlarge the astrophysical S-factor by more than a factor two. The matrix element ratio of the weak 3 He+p and the electromagnetic 3 He+n reaction is calculated to be (4.3±0.6)g A C 0 . This ratio has been found to be fairly insensitive to the percentage D-state admixtures in the 3 He and 4 He ground state wave functions. (author). 129 refs.; 24 figs.; 5 tabs

  11. Diffusion of πsup(+-) mesons on D, 3He, 4He with a streamer self-shunted camera in a magnetic field

    International Nuclear Information System (INIS)

    Atanasov, A.; Angelescu, T.; Balea, O.; Balestra, F.; Busso, L.; Garfagnini, R.

    1975-01-01

    A streamer self-shunted camera has been developed with the study of interactions of πsup(+-) mesons on D, 3 He, 4 He. The camera can operate at high beam currents (10 sup(5)/10sup(6)ssup(-1)), so processes with small cross sections can be studied

  12. Study of Interaction of Low-Energy Antiprotons with H$^{2}$,He$^{3}$,He$^{4}$,Ne-Nuclei Using a Streamer Chamber in Magnetic Field

    CERN Multimedia

    2002-01-01

    The aim of this experiment is the systematic study of the interaction between low-energy antiprotons and the H|2,~He|3,~He|4,~Ne-nuclei using a self shunted streamer chamber in a magnetic field exposed to the antiproton beam of the LEAR facility. The properties of the self shunted streamer chamber, which allows the use of the filling gas (hydrogen, helium, neon at a pressure of l~atm) as a target, permit to carry out experiments also in the very low-energy region. \\\\ \\\\ The experimental apparatus is suitable for a large programme of measurements. We plan to measure the @*H|2 cross section and the spectator momentum distributions at @* momenta lower than 250~MeV/c, where data are lacking. It is interesting to study for the first time the @*He|3 and @*He|4 interactions measuring the cross sections and the emitted particle distributions. Among other things the knowledge of the branching ratio of the @*He|4 annihilation channels clarifies some open cosmological questions. The study of the process of nuclear absor...

  13. Trojan horse particle invariance studied with the 6Li(d,α)4He and 7Li(p,α)4He reactions

    International Nuclear Information System (INIS)

    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.

    2011-01-01

    The Trojan horse nucleus invariance for the binary reaction cross section extracted from the Trojan horse reaction was tested using the quasifree 3 He( 6 Li,αα)H and 3 He( 7 Li,αα) 2 H reactions. The cross sections for the 6 Li(d,α) 4 He and 7 Li(p,α) 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 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.

  14. Probing the 8He ground state via the 8He(p,t)6He reaction

    International Nuclear Information System (INIS)

    Keeley, N.; Skaza, F.; Lapoux, V.; Alamanos, N.; Auger, F.; Beaumel, D.; Becheva, E.; Blumenfeld, Y.; Delaunay, F.; Drouart, A.; Gillibert, A.; Giot, L.; Kemper, K.W.; Nalpas, L.; Pakou, A.; Pollacco, E.C.; Raabe, R.; Roussel-Chomaz, P.; Rusek, K.; Scarpaci, J.-A.; Sida, J.-L.; Stepantsov, S.; Wolski, R.

    2007-01-01

    The weakly-bound 8 He nucleus exhibits a neutron halo or thick neutron skin and is generally considered to have an α+4n structure in its ground state, with the four valence neutrons each occupying 1p 3/2 states outside the α core. The 8 He(p,t) 6 He reaction is a sensitive probe of the ground state structure of 8 He, and we present a consistent analysis of new and existing data for this reaction at incident energies of 15.7 and 61.3A MeV, respectively. Our results are incompatible with the usual assumption of a pure (1p 3/2 ) 4 structure and suggest that other configurations such as (1p 3/2 ) 2 (1p 1/2 ) 2 may be present with significant probability in the ground state wave function of 8 He

  15. The (3He,t) and (d,2He)reactions at intermediate energies

    International Nuclear Information System (INIS)

    Brockstedt, A.

    1987-09-01

    The ( 3 He,t) reaction has been studied at 0.6-2.3 GeV at small scattering angles, 0-7 degrees, on various nuclei ( 12 C, 13 C, 26 Mg, 40 Ca, 48 Ca, 54 Fe, 90 Zr, 159 Tb, 208 Pb) including a proton target. The reaction is a single-step reaction and selects the spin-isospin channel. Angular distributions for low-lying states in 12 N are well described by DWIA calculations. From 13 C to 13 N transitions the ratio J στ /J τ , at momentum transfer, q, close to zero, is derived. The ratio remains roughly constant in the region 300 - 700 MeV/nucleon. The position of the quasi-free peak is shifted compared with free nucleon-nucleon scattering. The shift is towards higher excitation energies at q approx 1.4 fm -1 , and towards lower excitation energies at q approx 2.5 fm -1 . The p( 3 He,t)Δ ++ reaction is analysed as one-pion exchange and the ( 3 He,t) form factor is extracted. The shape and position of the Δ resonance seem to be independent of target mass for the targets studied. Compared with the p to Δ ++ transition the position is shifted towards lower excitation energy in nuclei. The (d,2p[ 1 S 0 ]) reaction, with the two protons in an 1 S 0 state labelled 2 He, is studied at 0.65 and 2.0 GeV at small angles, 0-4 degrees, on some of the targets used in the ( 3 He,t) experiment (p, 12 C, 40 Ca, 54 Fe). This reaction is also a one-step reaction that can be used for studies of spin-isospin excitations. Cross sections and tensor analysing powers are determined for the p(d, 2 He)n reaction. These results are compared with PWIA calculations. The Δ resonance in carbon is also here shifted down in excitation energy compared with the proton target. (author)

  16. Characteristics of spectators in 4He nuclei fragmentation processes

    International Nuclear Information System (INIS)

    Bano, M.; Braun, H.; Futo, A.

    1984-10-01

    Characteristics were studieO of deuteron, 3 H and 3 He spectators emitted in 4 He-p interactions at 8.6 GeV/c incident momentum. A model using the Monte Carlo procedure is proposed which predicts the momentum distribution for a nucleon or a group of nucleons (d, 3 H, 3 He) in the 4 He nucleus and describes some properties of reaction channels with spectator emission. The predictions are compared with experimental data. Good agreement is obtained taking into account the influence of the experimental errors and of the binding energy between the fragments. (author)

  17. Production of 4He and He4‾ in Pb-Pb collisions at √{sNN } = 2.76TeV at the LHC

    Science.gov (United States)

    Acharya, S.; Adamová, D.; Adolfsson, J.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Al-Turany, M.; Alam, S. N.; Albuquerque, D. S. D.; Aleksandrov, D.; Alessandro, B.; Alfaro Molina, R.; Ali, Y.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altenkamper, L.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andreou, D.; Andrews, H. A.; Andronic, A.; Anguelov, V.; Anson, C.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Ball, M.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barioglio, L.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartsch, E.; Bastid, N.; Basu, S.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Bazo Alba, J. L.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Beltran, L. G. E.; Belyaev, V.; Bencedi, G.; Beole, S.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhattacharjee, B.; Bhom, J.; Bianchi, A.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Blair, J. T.; Blau, D.; Blume, C.; Boca, G.; Bock, F.; Bogdanov, A.; Boldizsár, L.; Bombara, M.; Bonomi, G.; Bonora, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Botta, E.; Bourjau, C.; Bratrud, L.; Braun-Munzinger, P.; Bregant, M.; Broker, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buhler, P.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Cabala, J.; Caffarri, D.; Caines, H.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Capon, A. A.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Chandra, S.; Chang, B.; Chang, W.; Chapeland, S.; Chartier, M.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Chojnacki, M.; Choudhury, S.; Chowdhury, T.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Concas, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Costanza, S.; Crkovská, J.; Crochet, P.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danisch, M. C.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; de Souza, R. D.; Degenhardt, H. F.; Deisting, A.; Deloff, A.; Deplano, C.; Dhankher, P.; di Bari, D.; di Mauro, A.; di Nezza, P.; di Ruzza, B.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Ding, Y.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Doremalen, L. V. R.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dudi, S.; Duggal, A. K.; Dukhishyam, M.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erhardt, F.; Espagnon, B.; Eulisse, G.; Eum, J.; Evans, D.; Evdokimov, S.; Fabbietti, L.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Francisco, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gajdosova, K.; Gallio, M.; Galvan, C. D.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Garg, K.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Gay Ducati, M. B.; Germain, M.; Ghosh, J.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, A. S.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Graham, K. L.; Greiner, L.; Grelli, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Gronefeld, J. M.; Grosa, F.; Grosse-Oetringhaus, J. F.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Guzman, I. B.; Haake, R.; Hadjidakis, C.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Haque, M. R.; Harris, J. W.; Harton, A.; Hassan, H.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Hellbär, E.; Helstrup, H.; Herghelegiu, A.; Hernandez, E. G.; Herrera Corral, G.; Herrmann, F.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hills, C.; Hippolyte, B.; Hohlweger, B.; Horak, D.; Hornung, S.; Hosokawa, R.; Hristov, P.; Hughes, C.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Iga Buitron, S. A.; Ilkaev, R.; Inaba, M.; Ippolitov, M.; Islam, M. S.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacak, B.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jaelani, S.; Jahnke, C.; Jakubowska, M. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jercic, M.; Jimenez Bustamante, R. T.; Jones, P. G.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karczmarczyk, P.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Ketzer, B.; Khabanova, Z.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Khatun, A.; Khuntia, A.; Kielbowicz, M. M.; Kileng, B.; Kim, B.; Kim, D.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, J.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Konyushikhin, M.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Kreis, L.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kundu, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lai, Y. S.; Lakomov, I.; Langoy, R.; Lapidus, K.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lavicka, R.; Lea, R.; Leardini, L.; Lee, S.; Lehas, F.; Lehner, S.; Lehrbach, J.; Lemmon, R. C.; Leogrande, E.; León Monzón, I.; Lévai, P.; Li, X.; Lien, J.; Lietava, R.; Lim, B.; Lindal, S.; Lindenstruth, V.; Lindsay, S. W.; Lippmann, C.; Lisa, M. A.; Litichevskyi, V.; Llope, W. J.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Loncar, P.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Luhder, J. R.; Lunardon, M.; Luparello, G.; Lupi, M.; Lutz, T. H.; Maevskaya, A.; Mager, M.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martinengo, P.; Martinez, J. A. L.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Masciocchi, S.; Masera, M.; Masoni, A.; Masson, E.; Mastroserio, A.; Mathis, A. M.; Matuoka, P. F. T.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzilli, M.; Mazzoni, M. A.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Mhlanga, S.; Miake, Y.; Mieskolainen, M. M.; Mihaylov, D. L.; Mikhaylov, K.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, A. P.; Mohanty, B.; Mohisin Khan, M.; Montes, E.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mulligan, J. D.; Munhoz, M. G.; Münning, K.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Myers, C. J.; Myrcha, J. W.; Nag, D.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Narayan, A.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Negrao de Oliveira, R. A.; Nellen, L.; Nesbo, S. V.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, H.; Ohlson, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Oravec, M.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Pachmayer, Y.; Pacik, V.; Pagano, D.; Paić, G.; Palni, P.; Pan, J.; Pandey, A. K.; Panebianco, S.; Papikyan, V.; Pareek, P.; Park, J.; Parmar, S.; Passfeld, A.; Pathak, S. P.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Peng, X.; Pereira, L. G.; Pereira da Costa, H.; Peresunko, D.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Pezzi, R. P.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pliquett, F.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Poppenborg, H.; Porteboeuf-Houssais, S.; Pozdniakov, V.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Punin, V.; Putschke, J.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Rana, D. B.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Ratza, V.; Ravasenga, I.; Read, K. F.; Redlich, K.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reshetin, A.; Reygers, K.; Riabov, V.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rodríguez Cahuantzi, M.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Rokita, P. S.; Ronchetti, F.; Rosas, E. D.; Rosnet, P.; Rossi, A.; Rotondi, A.; Roukoutakis, F.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rueda, O. V.; Rui, R.; Rumyantsev, B.; Rustamov, A.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Saarinen, S.; Sadhu, S.; Sadovsky, S.; Šafařík, K.; Saha, S. K.; Sahlmuller, B.; Sahoo, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sandoval, A.; Sarkar, A.; Sarkar, D.; Sarkar, N.; Sarma, P.; Sas, M. H. P.; Scapparone, E.; Scarlassara, F.; Schaefer, B.; Scheid, H. S.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schmidt, M. O.; Schmidt, M.; Schmidt, N. V.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sett, P.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shahoyan, R.; Shaikh, W.; Shangaraev, A.; Sharma, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Sheikh, A. I.; Shigaki, K.; Shirinkin, S.; Shou, Q.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silaeva, S.; Silvermyr, D.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singhal, V.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Song, J.; Song, M.; Soramel, F.; Sorensen, S.; Sozzi, F.; Sputowska, I.; Stachel, J.; Stan, I.; Stankus, P.; Stenlund, E.; Stocco, D.; Storetvedt, M. M.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Sumowidagdo, S.; Suzuki, K.; Swain, S.; Szabo, A.; Szarka, I.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thakur, D.; Thakur, S.; Thomas, D.; Thoresen, F.; Tieulent, R.; Tikhonov, A.; Timmins, A. R.; Toia, A.; Toppi, M.; Torres, S. R.; Tripathy, S.; Trogolo, S.; Trombetta, G.; Tropp, L.; Trubnikov, V.; Trzaska, W. H.; Trzeciak, B. A.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Umaka, E. N.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vala, M.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vázquez Doce, O.; Vechernin, V.; Veen, A. M.; Velure, A.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Vértesi, R.; Vickovic, L.; Vigolo, S.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Virgili, T.; Vislavicius, V.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Voscek, D.; Vranic, D.; Vrláková, J.; Wagner, B.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wenzel, S. C.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilk, G.; Wilkinson, J.; Willems, G. A.; Williams, M. C. S.; Willsher, E.; Windelband, B.; Witt, W. E.; Xu, R.; Yalcin, S.; Yamakawa, K.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yun, E.; Yurchenko, V.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, Y.; Zichichi, A.; Zimmermann, M. B.; Zinovjev, G.; Zmeskal, J.; Zou, S.; Alice Collaboration

    2018-03-01

    Results on the production of 4He and He4‾ nuclei in Pb-Pb collisions at √{sNN } = 2.76TeV in the rapidity range | y | < 1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN / dy 4He = (0.8 ± 0.4 (stat) ± 0.3 (syst)) ×10-6 and dN / dyHe4‾ = (1.1 ± 0.4 (stat) ± 0.2 (syst)) ×10-6, respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (Tchem = 156MeV) as for light hadrons. The measured ratio of He4‾/4 He is 1.4 ± 0.8 (stat) ± 0.5 (syst).

  18. Temperature dependence of He(2 3PJ) reactions: Collision-induced mixing and conversion to He2( 3Πg) molecules

    International Nuclear Information System (INIS)

    Zhao, X.; Soletsky, P.A.; Bryan, W.H.; Dunning, F.B.; Walters, G.K.

    1993-01-01

    The rate coefficients for mixing between He(2 3 P J, MJ) levels during collisions with ground-state helium atoms and for conversion of He(2 3 P J ) atoms to He 2 (b 3 Π g ) molecules via three-body reactions in helium gas have been investigated over the temperature range 1.6--300 K. The measured rate coefficients for collisionally induced P-state mixing decrease slowly with decreasing temperature, from (1.8±0.5)x10 -9 cm 3 s -1 at 300 K to (4.5±0.5)x10 -10 cm 3 s -1 at 4.2 K. The rate coefficients for the production of He 2 (b 3 Π g ) molecules via three-body reactions are observed to increase with decreasing temperature and are described by the relation k P congruent(2.5+267T -1 )x10 -32 cm 6 s -1 . This behavior, which is very different from that noted in earlier studies of the conversion of He(2 3 S 1 ) atoms to He 2 (a 3 Σ u + ) molecules through three-body reactions, suggests that the reaction is not thermally activated

  19. A miniature adsorption3HE refrigerator

    International Nuclear Information System (INIS)

    Duband, L.; Ravex, A.; Lange, A.

    1991-01-01

    A self-contained, recyclable laboratory 3 He refrigerator has been developed. The refrigerator is very compact, portable and is designed to be safe and reliable. The unit can easily be installed on the cold plate of a superfluid 4 He cryostat. Once bolted on the cold plate, operation of the refrigerator is controlled by a single heater. In this new design the refrigerator has a cylindrical geometry. The adsorption pump is placed above the condensation point to prevent convection during the condensation phase and to improve the pumping speed. The inhibition of convection reduces the load on the 4 He bath and increases the condensation efficiency. This refrigeration technique has great potential for space applications. The absence of moving parts makes the system reliable and vibration free. Its simplicity and the absence of external components facilitate its integration on a cryostat. In fact, a rocket-borne 3 He refrigerator has already been successfully flown and has demonstrated the feasibility of this method

  20. The 3He Supply Problem

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.

    2009-05-01

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

  1. Manifestation of 12-quark bag state of sup 4 He nucleus in elastic d sup 4 He scattering

    CERN Document Server

    Mosallem, A M

    2002-01-01

    The sup 4 He d elastic scattering at the momentum of 19.8 GeV/c is analyzed in the framework of the Glauber theory. The scattering amplitude was evaluated using different sets of values of the nucleon-nucleon amplitude parameters and the sup 4 He density function as a superposition of the Gaussian functions. It is shown that it is impossible to describe simultaneously the p sup 4 He and d sup 4 He elastic scattering cross sections using the same set of the NN-amplitude parameters. Inclusion of the twelve-quark bag admixture to the ground state of the sup 4 He nucleus in the calculations allows one to reproduce the experimental data quite well. It is shown that the admixture manifests itself in the d sup 4 He elastic scattering in the whole region of the momentum transfer. At small t the effect can be at the level of approx 10%. At large t it can be approx 30%

  2. Helium (24He, 23He) within deuterated Pd-black

    International Nuclear Information System (INIS)

    Arata, Yoshiaki; Zhang, Yue-Chang

    1997-01-01

    Authors have clearly proven for the first time that deuterium nuclear reaction was continuously generated inside a highly deuterated solid by showing both of the excess energy and corresponding amount of helium as the reaction product generated simultaneously. Whenever there is a nuclear fusion reaction inside a metal, helium generated is unable to escape to the surroundings and is trapped in a frozen state inside that metal. The concentration of the helium within the metal will rise with increasing rate of reactions. Pd-black is under such state as the sample used and sealed within the 'closed QMS' developed by the authors (closed vessel including the Getter pump and the QMS). It is completely separated from the surroundings and the internal gases are removed to create super-vacuum. The reaction product released by the 'Sample-Heating' process (room temp. ↔ 1500(degC)) is thus the only matter which occupies the interior of the closed vessel and its detection by the QMS is assured. When the 'closed QMS' works under the above mentioned-state, it was clarified that the 'ash' or the reaction product of this fusion reaction within a solid is 2 4 He and 2 3 He and their ratio is 2 4 He/ 2 3 He4. It can be concluded from the result that the main reaction product is 2 4 He and it is created directly as an inherent feature of the solid-state nuclear fusion. Authors think that the reaction process responsible for the creation of 2 3 He may be a different one from that created 2 4 He. One of which is the Rutherford reaction process and the other occurs based on the specific properties of solid, similar to the case of 2 4 He. The existence of 1 3 T will be required that the process is responsible for the generation of 2 3 He as the Rutherford reaction. The proof for the existence of 1 3 T within the 'closed QMS', however, was not obtained in this experiments. (author)

  3. Neutron polarization in polarized 3He targets

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  4. Rb*Hen exciplexes in solid 4He

    International Nuclear Information System (INIS)

    Hofer, A.; Moroshkin, P.; Nettels, D.; Ulzega, S.; Weis, A.

    2006-01-01

    We report the observation of emission spectra from Rb*He n exciplexes in solid 4 He. Two different excitation channels were experimentally identified, viz., exciplex formation via laser excitation to the atomic 5P 3/2 and to the 5P 1/2 levels. While the former channel was observed before in liquid helium, on helium nanodroplets, and in helium gas by different groups, the latter creation mechanism occurs only in solid helium or in gaseous helium above 10 K. The experimental results are compared to theoretical predictions based on the extension of a model, used earlier by us for the description of Cs*He n exciplexes. We also report the observation of fluorescence from atomic rubidium in solid helium, and discuss striking differences between the spectroscopic features of Rb-He and Cs-He systems

  5. POLARIZED-LIGHT EMISSION IN KEV HE2++NA(3S) COLLISIONS

    NARCIS (Netherlands)

    BODUCH, P; VANBUCHEM, J; BLIEK, FW; HOEKSTRA, R; MORGENSTERN, R; OLSON, RE

    1995-01-01

    We investigated l and m-distributions of He II (n = 4) states formed during 2-13.3 keV amu(-1) He2+ + Na(3s) collisions by measuring profiles and the linear polarization of the He II (4 --> 3) emission. We found that at these energies capture into He+(4f) dominates over capture into other He+(4l)

  6. Bubble nucleation dynamics in 3He/4He mixture by holographic interferometry

    International Nuclear Information System (INIS)

    Morikawa, M; Abe, H; Nomura, R; Okuda, Y

    2009-01-01

    We were able to nucleate a gas bubble in the diluted phase of 3 He- 4 He mixture by a 1 ms width strong sound pulse. The nucleated bubble became large and detached from the bottom transducer and was pushed out to the bulk liquid by the acoustic wave pulse. The bubble then repeatedly expanded and contracted a few times and finally disappeared. The overall motion of the bubble was traced by a high speed camera with a time resolution of 1 ms. We are attempting to investigate the small density fluctuation around the bubble by incorporating holographic interferometry technology. The measurement was done at T=0.35 K for the phase separated mixture at saturated vapor pressure. An acoustic wave transducer was located at the bottom of the cell, so the bubble was nucleated in the dilute phase of the mixture. We resolved the density fluctuation as small as Δρ/ρ = 2 x 10 -6 in the dilute phase with the sample width of 25 mm, which could not be obtained by other methods. It was found that there appeared a less dense region of -Δρ/ρ ∼ 1.46 x 10 -3 just above the bubble. The bubble appeared just after the pulse was turned off, but this less dense region appeared prior to the emergence of the bulk bubble. It should be an important information about the bubble nucleation mechanism. This very high sensitivity of holographic interferometry with respect to the density fluctuation could be widely used in quantum liquid.

  7. Collisional energy transfer in Na(4p--3d)--He,H2 collisions

    International Nuclear Information System (INIS)

    Kleiber, P.D.; Wong, T.H.; Bililign, S.

    1993-01-01

    We have investigated the direct collisional energy transfer process Na*(4p)+M→Na*(3d)+M, where M=He,H 2 under gas cell conditions. We have measured the temporal profiles of the Na(3d--3p) sensitized fluorescence as a function of quenching gas pressure and fit the profiles to a two-state rate equation model to obtain the quenching rate coefficients from the Na*(4p) state. The total energy transfer rate coefficient out of the 4p state for He is small [(0.5±0.2)x10 -10 cm 3 /s]. The total quenching rate coefficient out of the 4p state is much larger for H 2 [(3.9±0.5)x10 -10 cm 3 /s]. Evidence suggests that the energy transfer rate coefficient for the 4p--3d process is ∼2.0x10 -10 cm 3 /s with the remainder of the 4p quenching being predominantly reactive. We also compare the far-red wing absorption line shapes for the NaHe and NaH 2 systems

  8. Strangeness production in antiproton annihilation at rest on 3He, 4He and 20Ne

    International Nuclear Information System (INIS)

    Balestra, F.; Batusov, Yu.A.; Falomkin, I.V.; Pontecorvo, G.B.; Rozhdestvensky, A.M.; Sapozhnikov, M.G.; Tretyak, V.I.; Bendiscioli, G.; Filippini, V.; Rotondi, A.; Salvini, P.; Venaglioni, A.; Bossolasco, S.; Bussa, M.P.; Busso, L.; Fava, L.; Ferrero, L.; Panzieri, D.; Piragino, G.; Tosello, F.; Breivik, F.O.; Danielsen, K.M.; Jacobsen, T.; Soerensen, S.O.; Guaraldo, C.; Maggiora, A.; Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.M.; Lodi Rizzini, E.; Brescia Univ.; Zenoni, A.; European Organization for Nuclear Research, Geneva

    1991-01-01

    New data are reported on antiproton annihilations at rest with production of Λ and K S 0 , using a streamer chamber with 3 He, 4 He and 20 Ne as gas targets. The data include Λ, K S 0 , ΛK S 0 and K S 0 K S 0 production rates and momentum distributions, π - momentum spectra, mean numbers of charged particles generally and of negatively charged particles separately for different reaction channels. The yields are compared to simple combinatorial calculations based on the extreme assumptions of Λ production via B=1 or via B=0 (anti K rescattering) annihilations. Λ and K S 0 momentum spectra are compared to simple model calculations where B=0 and B=1 annihilations with and without final-state interactions are considered. A review of existing data on Λ and K S 0 production is presented, showing the dependence on the anti p momentum and on the mass number of the target. (orig.)

  9. (3He,xn), (3He,pxn) and (3He, fission) reactions on 206Pb between 80 and 200MeV

    International Nuclear Information System (INIS)

    Andre, C.; Gauvin, H.; Le Beyec, Y.; Porile, N.T.

    1976-01-01

    The reactions induced in 206 Pb by 3 He particles having energies between 80 and 200MeV have been studied. Excitation functions for ( 3 He,xn) with x=3 to 14 and for ( 3 He,pxn) with x=2 to 5 have been obtained. Angular distributions of fission fragments were measured at 100, 125, 150 and 175MeV and total fission cross-sections were deduced from the data. On the basis of these results, analysis is attempted to examine the characteristics of reaction mechanisms. From these results it is concluded that non-compound processes play an important role in the reactions. Two features are characteristic of these processes: large cross-sections for charged particle emission and angular distribution of fission fragments closed to isotropy in the laboratory system. In the energy range 25 to 45MeV/nucleon, a comparison was made between the present results and those from an experimental study of α-particle induced reactions on 206 Pb. Also a comparison was made with an α-nucleus collision model applied to 206 Pb. All the observations strongly suggest a breakup of the projectile 3 He followed by the interactions of the fragments with the target nucleus [fr

  10. 3He neutral current detectors at SNO

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  11. Role of polarizability in the 3H(d,n)4He reaction

    International Nuclear Information System (INIS)

    Belyaev, V.B.; Kuzmichev, V.E.; Peresypkin, V.V.; Zepalova, M.L.

    1987-01-01

    The influence is investigated of the deuteron electric dipole polarizability on the cross section, astrophysical S-factor, and the yield of helium nuclei in the 3 H(d,n) 4 He reaction in the region of extremely low energies. Prediction is made of the existence of narrow maximum in the cross section at energies of an incident triton lower that 10 keV produced by the action of an attractive polarization potential in the d 3 H system. The growth of the cross section of d 3 H reaction increases the yield of 4 He nuclei at temperatures lower than keV

  12. 3He functions in tokamak-pumped laser systems

    International Nuclear Information System (INIS)

    Jassby, D.L.

    1986-10-01

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

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

    International Nuclear Information System (INIS)

    Lhuillier, C.; Laloe, F.

    1979-01-01

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

  14. HE4 Tissue Expression and Serum HE4 Levels in Healthy Individuals and Patients with Benign or Malignant Tumors

    DEFF Research Database (Denmark)

    Karlsen, Nikoline S; Karlsen, Mona A; Høgdall, Claus K

    2014-01-01

    , this review aims to systematically outline published results of HE4 tissue expression and serum HE4 levels in healthy individuals and patients with benign or malignant tumors. Our findings suggest scientific basis for a potential diagnostic ability of HE4 in gynecologic cancer and lung cancer, and further...

  15. Quasiparticle effects in the two-body photodisintegration of 4He

    International Nuclear Information System (INIS)

    Boettger, W.; Casel, A.; Sandhas, W.

    1979-09-01

    The total cross sections for the reactions 4 He(γ,n) 3 He and 4 He(γ,p) 3 H are calculated for photon energies between 50 MeV and 150 MeV in a quasiparticle formalism, leading to a simple interpretation for the γ-absorption mechanism. Results are compared with shell model calculations. (orig.)

  16. Cluster model study of the excited states of /sup 4/He

    Energy Technology Data Exchange (ETDEWEB)

    Furutani, H. [Osaka Univ., Suita (Japan). Research Center for Nuclear Physics; Ikegami, H.; Muraoka, M. [eds.; Osaka Univ., Suita (Japan). Research Center for Nuclear Physics

    1980-01-01

    Excited states of /sup 4/He are studied in the energy region E sub(x) = 20 -- 35 MeV within the framework of a (3N + N)-cluster model. (/sup 3/H + p) - (/sup 3/He + n) coupled channel calculation is carried out and results are compared with /sup 3/H(p, p)/sup 3/H, /sup 3/He(n, n)/sup 3/He and /sup 3/H(p, n)/sup 3/He reactions.

  17. Thermometry in 3He

    International Nuclear Information System (INIS)

    Richardson, R.C.

    1977-01-01

    Some of the methods used in measuring the temperatures of the transitions in 3 He are reviewed. Although noise thermometers, γ-ray anisotropy thermometers and even Pt NMR thermometers are satisfactory for furnishing temperature standards, they are not satisfactory secondary thermometers. The susceptibility of CMN and various 3 He properties make more precise and quicker thermometric indications. (Auth.)

  18. The unbound isotopes He-9,He-10

    CERN Document Server

    Jonson, B; Cortina-Gil, D; Simon, H; Emling, H; Nyman, G; Nilsson, T; Johansson, H T; Borge, M J G; Paschalis, S; Muenzenberg, G; Zhukov, M V; Weick, H; Pramanik, U Datta; LeBleis, T; Meister, M; Reifarth, R; Chulkov, L V; Lantz, M; Riisager, K; Mahata, K; Suemmerer, K; Langer, C; Chatillon, A; Richter, A; Kulessa, R; Palit, R; Aksyutina, Yu; Geissel, H; Aumann, T; Prokopowicz, W; Forssen, C; Ickert, G; Fynbo, H O U; Tengblad, O; Boretzky, K

    2010-01-01

    The unbound nuclei He-9 and He-10 have been produced in proton-knockout reactions from a 280 MeV/u Li-11 beam impinging on a liquid hydrogen target at the ALADIN-LAND setup at GSI. Information on their nuclear structure has been obtained from the relative-energy spectra, He-8 + n and He-8 + 2n, employing reaction models incorporating the structure of Li-11. The (8H)e + n relative-energy spectrum is dominated by a strong peak-like structure at low energy, which may be interpreted within the effective-range approximation as the result of an s-wave interaction with a neutron scattering length of -3.17(66) fm. This spectrum also shows evidence for resonance states at 1.33(8) MeV and at 2.4 MeV above the He-8 + n threshold. It is argued that the s-state might not be the He-9 ground state. For He-8 + n + n, the analysis of the relative-energy spectrum gives two alternative possibilities for an interpretation: either a narrow resonance at 1.42(10) MeV (Gamma = 1.11(76) MeV) superimposed on a correlated background, o...

  19. Influence of the intermediate bcc phase on the evolution of superfluid inclusions in hcp matrix 3He-4He

    International Nuclear Information System (INIS)

    Birchenko, A.P.; Mikhin, N.P.; Neoneta, A.S.; Rudavskij, Eh.Ya.; Fisun, Ya.Yu.

    2016-01-01

    The evolution of liquid inclusions which are formed in the hcp matrix by rapid cooling of the 3 He- 4 He solution containing 1.05% 3 He was studied by pulse NMR. The diffusion coefficient of 3 He in the liquid was measured by two-pulses spin-echo method during evolution of the inclusions. Measurements were carried out at 1.67 K which corresponds to the bcc phase existence in the phase diagram, as well as at 1.38 K, where the bcc phase is absent. It is found that in the process of the evolution, in both cases the size of the liquid inclusions is less than diffusion length and so the diffusion is restricted. The measured restricted dif-fusion coefficient allowed to find the characteristic size of the inclusions. In the first case, during the evolution of liquid inclusions, dendrites of intermediate bcc phase is forming and the inclusions are separating into a lot of smaller droplets. Due to the rapid growth of the bcc dendrites, the droplet size decreases rapidly, and the process comes to disappearance of bcc phase and an amorphous state appearance. The results obtained by measuring the diffusion coefficient, correlated with the behavior of the spin-lattice relaxation time in such a system. In the second case at a lower temperature bcc phase is not formed, and the size of the liquid inclusions decreases very slow until the completion of their solidification.

  20. Photodetachment cross sections for He-(4P0)

    International Nuclear Information System (INIS)

    Compton, R.N.; Alton, G.D.; Pegg, D.J.

    1980-01-01

    The first measurements are reported of photodetachment cross sections for He - (formed through charge exchange of He + with Ca vapor) over the photon energy range from 1.77 to 2.75 eV. The energies of autodetached electrons from the metastable He - beam have also been determined for the first time. The autodetached electron energy agrees within experimental error (+-0.25 eV) with the known 1s2s2p) 4 P 0 He - energy level. This taken with measurements for the lifetime of He - infers that charge exchange of He + with Ca vapor produces 4 P 0 He -

  1. On the 3He anomaly in hot subdwarf B stars

    Science.gov (United States)

    Schneider, David; Irrgang, Andreas; Heber, Ulrich; Nieva, Maria F.; Przybilla, Norbert

    2017-12-01

    Decades ago, 3He isotope enrichment in helium-weak B-type main-sequence, in blue horizontal branch and in hot subdwarf B (sdB) stars, i.e., helium-core burning stars of the extreme horizontal branch, were discovered. Diffusion processes in the atmosphere of these stars lead to the observed abundance anomalies. Quantitative spectral analyses of high-resolution spectra to derive photospheric isotopic helium abundance ratios for known 3He sdBs have not been performed yet. We present preliminary results of high-resolution and high S/N spectra to determine the 3He and 4He abundances of nine known 3He sdBs. We used a hybrid local/non-local thermodynamic equilibrium (LTE/NLTE) approach for B-type stars investigating multiple He i lines, including λ4922 Å and λ6678 Å, which show the strongest isotopic shifts in the optical spectral range.We also report the discovery of four new 3He sdBs from the ESO Supernova Progenitor survey. Most of the 3He sdBs cluster in a narrow temperature strip between ˜ 26000 K and ˜ 30000 K and have almost no atmospheric 4He at all. Interestingly, three 3He sdBs show evidence for vertical helium stratification.

  2. On the 3He anomaly in hot subdwarf B stars

    Directory of Open Access Journals (Sweden)

    Schneider David

    2017-12-01

    Full Text Available Decades ago, 3He isotope enrichment in helium-weak B-type main-sequence, in blue horizontal branch and in hot subdwarf B (sdB stars, i.e., helium-core burning stars of the extreme horizontal branch, were discovered. Diffusion processes in the atmosphere of these stars lead to the observed abundance anomalies. Quantitative spectral analyses of high-resolution spectra to derive photospheric isotopic helium abundance ratios for known 3He sdBs have not been performed yet. We present preliminary results of high-resolution and high S/N spectra to determine the 3He and 4He abundances of nine known 3He sdBs. We used a hybrid local/non-local thermodynamic equilibrium (LTE/NLTE approach for B-type stars investigating multiple He i lines, including λ4922 Å and λ6678 Å, which show the strongest isotopic shifts in the optical spectral range.We also report the discovery of four new 3He sdBs from the ESO Supernova Progenitor survey. Most of the 3He sdBs cluster in a narrow temperature strip between ∼ 26000 K and ∼ 30000 K and have almost no atmospheric 4He at all. Interestingly, three 3He sdBs show evidence for vertical helium stratification.

  3. Liquid-4He target with a small refrigerator

    International Nuclear Information System (INIS)

    Kato, S.; Kitami, T.; Maruyama, K.; Murata, Y.; Endo, S.; Niki, K.; Morita, T.

    1989-10-01

    A liquid- 4 He target system with a small refrigerator has been developed for the first time to study γ 4 He reactions at intermediate energies. The density of the target is controlled within an accuracy of 3 %. The target system has been operated successfully for more than 1,000 hours of the experiment using the π-sr TAGX spectrometer at the 1.3-GeV Tokyo electron synchrotron. (author)

  4. Mass spectrometer determinations of solar wind He, Ne, and Ar and radiation belt He

    International Nuclear Information System (INIS)

    Warasila, R.L.

    1976-01-01

    A unique mass spectrometer system was built and used to measure He, Ne, and Ar abundances and isotopic ratios in various samples of spacecraft that have been exposed to the space environment. The Apollo 12 mission brought back sections of the Surveyor 3 vehicle suitable for mass spectrometric studies of implanted solar wind and solar cosmic ray particles. Using the mass spectrometer, a 4 He flux of 6-8 x 10 6 ions/cm 2 --sec was measured, and in addition 4 He/ 3 He = 2700 +- 50; 4 He/ 20 Ne = 410 + 30; 20 Ne/ 22 Ne = 13.5 +- 0.2; 20 Ne/ 36 Ar = 24.5 +- 2.5; and 36 Ar/ 38 Ar = 5.41 +- 0.20 isotopic abundances were measured. An upper limit for the flux of SCR 3 He in the 10-20 MeV/nucleon range was also determined, for the thirty-one month exposure period. In the radiation belt environment, 3 He was found in the aluminum antenna housing from the recovered second stage of a pre-Apollo Saturn test flight launched January 28, 1964 and returned to earth on April 28, 1966. The amount of 3 He found was about 6 x 10 -10 cc(STP)/cm 2 with a 4 He/ 3 He ratio of 145 or less. The 3 He was shown to come from the lower radiation belt as all other sources of 3 He were orders of magnitude lower than the observed value

  5. Is There a Pronounced Giant Dipole Resonance in 4He?

    International Nuclear Information System (INIS)

    Efros, V.D.; Efros, V.D.; Leidemann, W.; Orlandini, G.; Orlandini, G.

    1997-01-01

    A four-nucleon calculation of the total 4 He photodisintegration cross section is performed. The full final-state interaction is taken into account for the first time. This is achieved via the method of the Lorentz integral transform. Semirealistic NN interactions are employed. Different from the known partial two-body 4 He( γ,n) 3 He and 4 He( γ,p) 3 H cross sections our total cross section exhibits a pronounced giant resonance. Thus, in contrast to older (γ,np) data, we predict quite a strong contribution of the (γ,np) channel at the giant resonance peak energy. copyright 1997 The American Physical Society

  6. Specific heat near the Lambda point in 4He and 3He- 4He mixtures: test of universality of the critical exponent and the amplitude ratio, and observation of the critical-tricritical crossover effect

    International Nuclear Information System (INIS)

    Takada, T.; Watanabe, T.

    1980-01-01

    The specific heat under saturated vapor pressure of pure 4 He and of six 3 He- 4 He mixtures up to X=0.545 was measured in the temperature range 3 x 10 -6 -2 K. The critical exponents α/sub phi/ and α'/sub phi/ along the path phi=phi/sub lambda/ are independent of X up to X=0.545, where phi(=μ 34 ) is the difference between chemical potentials. If we take account of higher order terms, the exponent α/sub phi/(=α'/sub phi/) and the amplitude ratio A/sub //A'are independent of X up to X=0.545. The values of α/sub phi/ and A/sub //A'/sub phi/ are -0.023 and 1.090, respectively. The critical-tricriticall crossover effect was observed for X=0.545 and the boundary of crossover region closest to the critical region was at theta/T/sub lambda/1(times)=10 -4 , where theta is the distance Vertical BarT-T/sub lambda/Vertical Bar along the path phi=phi/sub lambda/. This value is in good agreement with the estimated value by Riedel et al. But, remarkably, in the case of X=0.439 this effect was not observed

  7. BBN predictions for 4He

    International Nuclear Information System (INIS)

    Walker, T.P.

    1993-01-01

    The standard model of the hot big bang assumes a homogeneous and isotropic Universe with gravity described by General Relativity and strong and electroweak interactions described by the Standard Model of particle physics. The hot big bang model makes the unavoidable prediction that the production of primordial elements occurred about one minute after the big band (referred to as big bang or primordial nucleosynthesis BBN). This review concerns the range of the primordial abundance of 4 He as predicted by standard BBN (i.e., primordial nucleosynthesis assuming a homogeneous distribution of baryons). In it the author discusses: (1) Uncertainties in the calculation of Y p (the mass fraction of primordial 4 He), (2) The expected range of Y p , (3) How the predictions stack up against the latest observations, and (4) The latest BBN bounds on Ω B h 2 and N ν . 13 refs., 2 figs

  8. Noble Gases in Alpine Gold: U/Th-He Dating and Excesses of Radiogenic He and AR

    Science.gov (United States)

    Eugster, O.; Hofmann, B.; Krahenbuhl, U.; Neuenschwander, J.

    1992-07-01

    Gold precipitates in hydrothermal fluids along with other heavy elements, such as Ag and Pt. In order to explore the possibility of dating the formation of gold we determined the concentrations of U, Th, and their decay product ^4He, as well as the K and ^40Ar concentrations in vein-type gold and in placer gold samples. The gold-quartz veins at Brusson in the south-western alps were formed approximately 32 Ma ago during an episode of tectonic uplift (Diamond, 1990). Alpine material was deposited as sediment layers in the region of central Switzerland and placer gold is thus relatively abundant in the rivers of the Napf area. We washed placer gold from the river Grosse Fontanne in 1990 and 1991. Placer gold that had been collected from the river Kruempelgraben in 1933 and a sample of vein-type free gold grown on quartz rock from the Brusson area (Val d'Ayas) have been obtained from the Museum of Natural History in Bern. Table 1 gives the results. Most of the ^4He is released above 1050 degrees C, that is when gold melts, indicating that gold is extremely well retentive for He. From the ^4He concentration of (269 +- 20) x 10^-8 cm^3 STP/g, (0.4 +- 0.1) ppm U, and (0.9 +- 0.3) ppm Th for vein-type gold we calculate a U/Th-He age of (36 +- 8)Ma. This age agrees within errors with the proposed age of 32 Ma. The data given in Table 1 show that all placer gold samples contain excesses of radiogenic ^4He and ^40Ar relative to the concentrations expected from the U/Th and K decay, respectively, if we assume a formation age of 32 Ma. The quartz sample is depleted in ^4He but strongly enriched in radiogenic ^40Ar. The excess of ^40Ar(sub)rad is easier to explain than that of ^4He. Vein-type gold and placer gold contain quartz inclusions (Schmid, 1973). The high ^40Ar(sub)rad content of quartz (Table 1) indicates that the ^40Ar(sub)rad excess of gold originates from quartz inclusions. Excess ^4He in gold must be of radiogenic origin. Taking ^20Ne and ^36Ar as a measure for the

  9. Effect of rotation on the elastic moduli of solid 4He

    Science.gov (United States)

    Tsuiki, T.; Takahashi, D.; Murakawa, S.; Okuda, Y.; Kono, K.; Shirahama, K.

    2018-02-01

    We report measurements of elastic moduli of hcp solid 4He down to 15 mK when the samples are rotated unidirectionally. Recent investigations have revealed that the elastic behavior of solid 4He is dominated by gliding of dislocations and pinning of them by 3He impurities, which move in the solidlike Bloch waves (impuritons). Motivated by the recent controversy of torsional oscillator studies, we have performed direct measurements of shear and Young's moduli of annular solid 4He using pairs of quarter-circle-shape piezoelectric transducers (PZTs) while the whole apparatus is rotated with angular velocity Ω up to 4 rad/s. We have found that shear modulus μ is suppressed by rotation below 80 mK, when shear strain applied by PZT exceeds a critical value, above which μ decreases because the shear strain unbinds dislocations from 3He impurities. The rotation-induced decrement of μ at Ω =4 rad/s is about 14.7(12.3)% of the total change of temperature dependent μ for solid samples of pressure 3.6(5.4) MPa. The decrements indicate that the probability of pinning of 3He on dislocation segment G decreases by several orders of magnitude. We propose that the motion of 3He impuritons under rotation becomes strongly anisotropic by the Coriolis force, resulting a decrease in G for dislocation lines aligning parallel to the rotation axis.

  10. Photodisintegration of 3H and 3He

    International Nuclear Information System (INIS)

    Faul, D.D.

    1980-09-01

    The photoneutron cross sections for 3 H and 3 He have been measured from threshold to approx. 25 MeV with monoenergetic photons from the annihilation in flight of fast positrons at the LLL Electron-Positron Linear Accelerator facility. These reactions include the two-body breakup of 3 H and the three-body breakup of both 3 H and 3 He; these measurements for 3 H are the first to span the energy region across the peaks of the cross sections. An efficient BF 3 -tube-and-paraffin neutron detector and high-pressure gaseous samples of several moles each (the activity of the 3 H sample was approx. 200,000 Ci) were employed in these measurements. Measurements on 16 O and 2 H also were performed to verify the absolute cross-section scale. The results, when compared with each other and with results for the two-body breakup cross section for 3 He from the literature, show that the two-body breakup cross sections for 3 H and 3 He have nearly the same shape, but the one for 3 He lies lower in magnitude; the three-body breakup cross section for 3 He lies higher in magnitude and is broader in the peak region and also rises less sharply from threshold than that for 3 H; and these measured differences between the cross sections for the breakup modes largely compensate in their sum, so that the total photon absorption cross sections for 3 H and 3 He are nearly the same in both size and shape at energies near and above their peaks. Theoretical results from the literature disagree with the experimental results to a certain extent over the entire photon-energy region for which the photoneutron cross sections were measured. 50 figures, 7 tables

  11. Interaction of a 29 MeV 3{sup H}e particle beam with a Cl{sub 4}C vapour target; Interacciones de He{sup 3} de 29 MeV en un blanco de Cl{sub 4}C

    Energy Technology Data Exchange (ETDEWEB)

    Lleo Morilla, A

    1963-07-01

    The interactions of a 29 MeV 3{sup H}e particles beam on a Cl{sub 4}C vapour target have been studied using the photographic method. differential cross-sections for the Cl({sup 3}He, {sup 3}He)Cl elastic scattering and {sup 1}2C({sup 3}He, {alpha}){sup 1}1C pick-up reaction are shown; the corresponding angular distributions in the centre-of-mass system have been compared with the predictions of optical model and A.B.M. theories. (Author) 21 refs.

  12. Antimicrobial actions of the human epididymis 2 (HE2 protein isoforms, HE2alpha, HE2beta1 and HE2beta2

    Directory of Open Access Journals (Sweden)

    French Frank S

    2004-08-01

    Full Text Available Abstract Background The HE2 gene encodes a group of isoforms with similarities to the antimicrobial beta-defensins. We demonstrated earlier that the antimicrobial activity of HE2 proteins and peptides is salt resistant and structure dependent and involves permeabilization of bacterial membranes. In this study, we further characterize the antimicrobial properties of HE2 peptides in terms of the structural changes induced in E. coli and the inhibition of macromolecular synthesis. Methods E. coli treated with 50 micro g/ml of HE2alpha, HE2beta1 or HE2beta2 peptides for 30 and 60 min were visualized using transmission and scanning electron microscopy to investigate the impact of these peptides on bacterial internal and external structure. The effects of HE2alpha, HE2beta1 and HE2beta2 on E. coli macromolecular synthesis was assayed by incubating the bacteria with 2, 10 and 25 micro g/ml of the individual peptides for 0–60 min and measuring the incorporation of the radioactive precursors [methyl-3H]thymidine, [5-3H]uridine and L-[4,5-3H(N]leucine into DNA, RNA and protein. Statistical analyses using Student's t-test were performed using Sigma Plot software. Values shown are Mean ± S.D. Results E. coli treated with HE2alpha, HE2beta1 and HE2beta2 peptides as visualized by transmission electron microscopy showed extensive damage characterized by membrane blebbing, thickening of the membrane, highly granulated cytoplasm and appearance of vacuoles in contrast to the smooth and continuous membrane structure of the untreated bacteria. Similarly, bacteria observed by scanning electron microscopy after treating with HE2alpha, HE2beta1 or HE2beta2 peptides exhibited membrane blebbing and wrinkling, leakage of cellular contents, especially at the dividing septa, and external accumulation of fibrous materials. In addition, HE2alpha, HE2beta1 and HE2beta2 peptides inhibited E. coli DNA, RNA and protein synthesis. Conclusions The morphological changes observed

  13. Absolute Charge Exchange Cross Sections for ^3He^2+ Collisions with ^4He and H_2

    Science.gov (United States)

    Mawhorter, R. J.; Greenwood, J.; Smith, S. J.; Chutjian, A.

    2002-05-01

    The JPL charge exchange beam-line(J.B. Greenwood, et al., Phys. Rev A 63), 062707 (2001) was modified to increase the forward acceptance angle and enable the measurement of total charge-exchange cross sections for slow, light, highly-charged ion collisions with neutral targets(R. E. Olson and M. Kimura, J. Phys. B 15), 4231 (1982). Data are presented for single charge exchange cross sections for ^3He^2+ nuclei scattered by ^4He and H2 in the energy range 0.33-4.67 keV/amu. For both targets there is good agreement with Kusakabe, et al.(T. Kusakabe, et al., J. Phys. Soc. Japan 59), 1218 (1990). Angular collection is studied by a comparison with differential measurements(D. Bordenave-Montesquieu and R. Dagnac, J. Phys. B 27), 543 (1994), as well as with earlier JPL results(J.B. Greenwood, et al., Ap. J. 533), L175 (2000), ibid. 529, 605 (2000) using heavier projectiles and targets. This work was carried out at JPL/Caltech, and was supported through contract with NASA. RJM thanks the NRC for a Senior Associateship at JPL.

  14. On the thermophysical and transport properties of 3He and 4He: A bubble interaction potential versus state of the art.

    Science.gov (United States)

    Chrysos, Michael; Piel, Henri

    2017-07-21

    Three keynote thermophysical and transport properties of 3 He and 4 He, namely, the second virial coefficient, the shear viscosity, and the thermal conductivity, are reported for the "extended Dirac bubble potential" (EDbp), a novel model for He-He [M. Chrysos, J. Chem. Phys. 146, 024106 (2017)]. Comparisons with the experiment as well as with potentials with a proven track record and with the oversimplified Dbp are being made in the range 0.1-500 K to analyze the performance of the EDbp, which is shown here to emerge as a promising analytic model for He-He. A flowchart of how to treat the "buffer" in scattering cross section measurements is designed and conducted, offering a route to EDbp optimization. An impressive consistency with state-of-the-art calculations (which is just striking for such a simple analytic model) is found, essentially thanks to the performance of the phase-shift expression cotδ l  = λkr 0 ξ l y l (kr 0 )-y l (kr c )λkr 0 ξ l j l (kr 0 )-j l (kr c ), ξ l =j l (kr 0 )y l (kr c )-j l (kr c )y l (kr 0 ). A Multimedia view of δ l (k,r c ) versus k and r c is part of the material presented in this article. Data for the "best" r c (k) is given as a supplementary material.

  15. Determination of the spin polarization of a 4He+ ion beam

    International Nuclear Information System (INIS)

    Suzuki, T.; Yamauchi, Y.

    2008-01-01

    It was demonstrated that the spin polarization of a 4 He + ion beam (P He + ) can be determined from the spin dependence of the electron emission in the deexcitation process of spin-polarized He metastable atoms (He*, 2 3 S 1 ) and spin-polarized He + ions on Fe (100) surfaces. On Fe (100) surfaces, both He* and He + deexcite via Auger neutralization, and therefore, the spin asymmetry obtained from spin-polarized He + ion neutralization spectroscopy should be equal to that from spin-polarized metastable He* deexcitation spectroscopy. The spin polarization of He* was obtained from Stern-Gerlach measurements. P He + was finally determined to be 0.19±0.02

  16. Homogeneous nucleation in 4He: A corresponding-states analysis

    International Nuclear Information System (INIS)

    Sinha, D.N.; Semura, J.S.; Brodie, L.C.

    1982-01-01

    We report homogeneous-nucleation-temperature measurements in liquid 4 He over a bath-temperature range 2.31 4 He, in a region far from the critical point. A simple empirical form is presented for estimating the homogeneous nucleation temperatures for any liquid with a spherically symmetric interatomic potential. The 4 He data are compared with nucleation data for Ar, Kr, Xe, and H; theoretical predictions for 3 He are given in terms of reduced quantities. It is shown that the nucleation data for both quantum and classical liquids obey a quantum law of corresponding states (QCS). On the basis of this QCS analysis, predictions of homogeneous nucleation temperatures are made for hydrogen isotopes such as HD, DT, HT, and T 2

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Jassby, D.L.

    1986-10-01

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

  19. Calculation of the energy of particles emitted by the reactions {sup 3}{sub 1}T (d,n) {sup 4}{sub 2}He, D (d,n) {sup 3}{sub 2}He and D (d,p) T; Calcul de l'energie des particules emises par les reactions {sup 3}{sub 1}T (d,n) {sup 4}{sub 2}He, D (d,n) {sup 3}{sub 2}He et D (d,p) T

    Energy Technology Data Exchange (ETDEWEB)

    Oria, M; Sorriaux, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    With a view to ease the work of research workers using 150 kV electrostatic accelerators, we have calculated the energy and the emission angle of particles emitted during the reactions {sub 1}{sup 3}T(d,n){sub 2}{sup 4}He, {sub 1}{sup 2}D(d,n){sub 2}{sup 3}He and {sub 1}{sup 2}D(d,p){sub 1}{sup 3}T. The results are classified in tables and arranged according to the acceleration energy of the deuterons. Since the energies considered are relatively low we have limited our study to the non-relativistic domain; this simplification results in a maximum energy variation with respect to the real energy values of 1 per cent. We give also two curves representing the variations in the total cross-sections for the reactions T (d,n){sub 2}{sup 4}He and D (d,n){sub 2}{sup 3}He. (authors) [French] De facon a faciliter la tache des experimentateurs utilisant des accelerateurs electrostatiques de 150 kV, nous avons calcule l'energie et l'angle d'emission des particules emises lors des reactions {sub 1}{sup 3}T(d,n){sub 2}{sup 4}He, {sub 1}{sup 2}D(d,n){sub 2}{sup 3}He and {sub 1}{sup 2}D(d,p){sub 1}{sup 3}T. Les resultats ont ete classes dans des tableaux, et ordonnes en fonction de l'energie d'acceleration des deuterons. Les energies considerees etant relativement peu elevees, nous avons limite notre etude au domaine non relativiste, cette simplification n'entraine qu'une variation maximale de 1 pour cent sur les valeurs reelles des energies. Nous avons joint a ce calcul deux courbes representant la variation des sections efficaces totales des reactions T (d,n){sub 2}{sup 4}He et D (d,n){sub 2}{sup 3}He. (auteurs)

  20. The Cosmic Abundance of 3He: Green Bank Telescope Observations

    Science.gov (United States)

    Balser, Dana; Bania, Thomas

    2018-01-01

    The Big Bang theory for the origin of the Universe predicts that during the first ~1,000 seconds significant amounts of the light elements (2H, 3He, 4He, and 7Li) were produced. Many generations of stellar evolution in the Galaxy modifies these primordial abundances. Observations of the 3He+ hyperfine transition in Galactic HII regions reveals a 3He/H abundance ratio that is constant with Galactocentric radius to within the uncertainties, and is consistent with the primordial value as determined from cosmic microwave background experiments (e.g., WMAP). This "3He Plateau" indicates that the net production and destruction of 3He in stars is approximately zero. Recent stellar evolution models that include thermohaline mixing, however, predict that 3He/H abundance ratios should slightly decrease with Galactocentric radius, or in places in the Galaxy with lower star formation rates. Here we discuss sensitive Green Bank Telescope (GBT) observations of 3He+ at 3.46 cm in a subset of our HII region sample. We develop HII region models and derive accurate 3He/H abundance ratios to better constrain these new stellar evolution models.

  1. Measurements of the osmotic pressure in liquid mixtures of 3He and 4He near the lambda line and tricritical point

    International Nuclear Information System (INIS)

    Gearhart, C.A. Jr.

    1977-06-01

    Values of the concentration susceptibility near the lambda line and tricritical point in liquid mixtures of 3 He and 4 He have been calculated from measurements of osmotic pressure differences. Measurements were made by inducing a small 3 He mole fraction difference Δx between two chambers separated by a pressure transducer, and measuring the resulting osmotic pressure difference as a function of temperature. Osmotic equilibrium was established through a Vycor glass superleak, which for 3 He mole fraction x > 0.55 functions not only in the superfluid phase but in portions of the normal fluid region of the phase diagram as well. Measurements were made at four 3 He mole fractions, x = 0.59, x = 0.64, x = 0.68, and x = 0.70. In contrast with determinations from light scattering and vapor pressure measurements, the present measurements show a pronounced peak at the lambda transition for the two values of x less than the tricritical value (x/sub t/ = 0.675). The susceptibilities are consistent with α = 0 both above and below the lambda transition except at x = 0.64, where some combination of α and α' greater than zero seems to be preferred. (The result α = 0 corresponds to a logarithmic divergence.) It is possible that this positive value of α or α' represents the influence of tricritical effects. It should be emphasized that there is considerable ambiguity in our determination of α, with acceptable least-squares fits corresponding to values of α between 0.0 and 0.2 being found at both concentrations, both above and below T/sub lambda/. The results appear to be consistent with the results of other experiments away from the lambda line, and also to be consistent with a simple tricritical scaling relationship

  2. Neutral hydrogen from the foil-induced dissociation of 4HeH+, 3HeH+, and H2+

    International Nuclear Information System (INIS)

    Cooney, P.J.; Gemmell, D.S.; Kanter, E.P.; Pietsch, W.J.; Zabransky, B.J.

    1979-01-01

    High resolution energy spectra and angular distributions of H 0 from the dissociation of 4 HeH + , 3 HeH + , and H 2 + in thin carbon foils are presented for incident ion energies ranging from 170 to 1800 keV/amu. For the range of dwell times inside the target foils studied (about 1 to 10 fsec), the dominant mechanism for such dissociation is the Coulomb explosion of the ions inside the target followed by electron capture near the rear surface of the foil. At the shortest of these dwell times, the yield of H 0 for incident ions oriented perpendicular to the beam relative to that for ions aligned with the beam is a factor of two greater than at longer dwell times. These data indicate that, for ion fragments which emerge from the rear surface of the target within a few angstroms of one another, those in the perpendicular orientation have a greater electron capture probability than those emerging in other orientations. 9 references

  3. A new type of liquid-3He target system using small mechanical refrigerators

    International Nuclear Information System (INIS)

    Kato, S.; Kobayashi, K.; Maruyama, K.; Okuno, H.; Konno, O.; Suda, T.; Maki, T.; Asami, H.; Koizumi, T.

    1991-04-01

    A new type of liquid- 3 He target has been developed for photoabsorption experiments at intermediate energies. Using the cooling power of liquid 4 He at reduced vapour pressure, 3 He gas is liquefied into a cylindrical target cell of 180 ml and is maintained at 2.0 K during the experiment. Evaporated 4 He gas is evacuated by a rotary pump and returned into the 4 He bath in the cryostat, where two small mechanical refrigerators with cooling capacities of 3 W at 4.3 K and 10 W at 20 K are operated for the purpose of 4 He recondensation. A maintenance-free operation of more than 1,000 hours has become possible by adopting the 4 He circulation system. (author)

  4. 3He Abundances in Planetary Nebulae

    Science.gov (United States)

    Guzman-Ramirez, Lizette

    2017-10-01

    Determination of the 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in stars which evolve through the planetary nebula phase. Planetary nebulae are the final evolutionary phase of low- and intermediate-mass stars, where the extensive mass lost by the star on the asymptotic giant branch is ionised by the emerging white dwarf. This ejecta quickly disperses and merges with the surrounding ISM. 3He abundances in planetary nebulae have been derived from the hyperfine transition of the ionised 3He, 3He+, at the radio rest frequency 8.665 GHz. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. Many hours have been put into trying to detect this line, using telescopes like the Effelsberg 100m dish of the Max Planck Institute for Radio Astronomy, the National Radio Astronomy Observatory (NRAO) 140-foot telescope, the NRAO Very Large Array, the Arecibo antenna, the Green Bank Telescope, and only just recently, the Deep Space Station 63 antenna from the Madrid Deep Space Communications Complex.

  5. The 3H–3He Charge Radii Difference

    Directory of Open Access Journals (Sweden)

    Myers L. S.

    2016-01-01

    Full Text Available The upcoming E12-14-009 [1] experiment at Jefferson Lab will determine the ratio of the electric form factors for the A=3 mirror nuclei 3He and 3H. The measurement will use a 1.1 GeV electron beam, a special collimator plate to allow for simultaneous optics measurements, and the low-activity tritium target being prepared for Jefferson Lab. By observing the dependence of the form factor ratio as a function of Q2 over 0.05–0.09 GeV2, the dependence of the radii extraction on the shape of the form factors is minimized. As a result, we anticipate the uncertainty of the extracted charge radii difference to be 0.03 fm, a reduction of 70% from the current measurement. Using precise measurements of the 3He charge radius from isotopic shift or μHe measurements [2–4], we can deduce the absolute 3H charge radius. The results will provide a direct comparison to recent calculations of the charge radii.

  6. Atomic interaction with quantum fluid clusters: cross-jet deflection of 3He- and 4He-clusters

    International Nuclear Information System (INIS)

    Gspann, J.; Vollmar, H.

    1977-01-01

    The authors have studied earlier the velocity dependence of the total scattering of Cs atomic beams by 4 He-cluster beams, in comparison with corresponding experiments with N 2 - and Ne-cluster beams. Only with the 4 He-cluster beams a deficiency in the effective total scattering compared to the expected behaviour has been observed which was largest near 200 m/s of relative velocity. However, it is difficult to estimate, and therefore still a matter of investigation, to which extent this effect could be attributed to the presence of a small amount of uncondensed helium atoms in the cluster beam. In this paper a first account is given on an experimental study of the drag coefficients in free molecular flow of helium clusters of either isotope. The drag coefficients describe the respective efficiencies of linear momentum transfer onto the clusters and are found to be appreciably lower for helium than for nitrogen clusters which is ascribed to the fluidity of the helium clusters. (Auth.)

  7. Measurement of fast minority /sub 3/He/sup + +/ energy distribution during ICRF heating

    Science.gov (United States)

    Post, D.E. Jr.; Grisham, L.R.; Medley, S.S.

    A method and means for measuring the fast /sub 3/He/sup + +/ distribution during /sub 3/He/sup + +/ minority Ion Cyclotron Resonance Frequency (ICRF) heating is disclosed. The present invention involves the use of 10 to 100 keV beams of neutral helium atoms to neutralize the fast /sub 3/He/sup + +/ ions in a heated plasma by double charge exchange (/sub 3/He/sup + +/ + /sub 4/He/sup 0/ ..-->.. /sub 3/He/sup 0/ + /sub 4/He/sup + +/). The neutralized fast /sub 3/He/sup 0/ atoms then escape from the hot plasma confined by a magnetic field and are detected by conventional neutral particle analyzing means. This technique permits the effectiveness of the coupling of the ion cyclotron waves to the /sub 3/He/sup + +/ minority ions to be accurately measured. The present invention is particularly adapted for use in evaluating the effectiveness of the intermediate coupling between the RF heating and the /sub 3/He/sup + +/ in an energetic toroidal plasma.

  8. Pionic annihilation of antiprotons stopped on 3He

    International Nuclear Information System (INIS)

    Bendiscioli, G.; Filippini, V.; Rotondi, A.; Salvini, P.; Venaglioni, A.; Bossolasco, S.; Bussa, M.P.; Busso, L.; Fava, L.; Ferrero, L.; Maggiora, A.; Panzieri, D.; Piragino, G.; Piragino, R.; Tosello, F.; Batusov, Yu.A.; Falomkin, I.V.; Pontecorvo, G.B.; Rozhdestvensky, A.M.; Sapozhnikov, M.G.; Tretyak, V.I.; Guaraldo, C.; Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.M.; Zenoni, A.

    1990-01-01

    The pionic annihilation of antiprotons stopped on 3 He nuclei in a self-shunted streamer chamber exposed to the antiproton beam of LEAR is studied. The data concern charged-particle multiplicity distributions, branching ratios for different final states, the probability of final-state interaction, π - , π + , p and d momentum spectra, like and unlike pion angular correlations, π and other charged-particle angular correlations. The comparison of the 3 He data with those obtained on 1 H, 2 H and 4 He does not reveal relevant effects due to the increase of the nucleon number; the small differences can be seen as due to a weak final-state interaction. (orig.)

  9. Accurate 3He polarimetry using the Rb Zeeman frequency shift due to the Rb-3He spin-exchange collisions

    International Nuclear Information System (INIS)

    Romalis, M.V.; Cates, G.D.

    1998-01-01

    We describe a method of 3 He polarimetry relying on the polarization-dependent frequency shift of the Rb Zeeman resonance. Our method is ideally suited for on-line measurements of the 3 He polarization produced by spin-exchange optical pumping. To calibrate the frequency shift we performed an accurate measurement of the imaginary part of the Rb- 3 He spin-exchange cross section in the temperature range typical for spin-exchange optical pumping of 3 He. We also present a detailed study of possible systematic errors in the frequency shift polarimetry. copyright 1998 The American Physical Society

  10. Calculations of long-range three-body interactions for He(n0λS )-He(n0λS )-He(n0'λL )

    Science.gov (United States)

    Yan, Pei-Gen; Tang, Li-Yan; Yan, Zong-Chao; Babb, James F.

    2018-04-01

    We theoretically investigate long-range interactions between an excited L -state He atom and two identical S -state He atoms for the cases of the three atoms all in spin-singlet states or all in spin-triplet states, denoted by He(n0λS )-He(n0λS )-He(n0'λL ), with n0 and n0' principal quantum numbers, λ =1 or 3 the spin multiplicity, and L the orbital angular momentum of a He atom. Using degenerate perturbation theory for the energies up to second-order, we evaluate the coefficients C3 of the first-order dipolar interactions and the coefficients C6 and C8 of the second-order additive and nonadditive interactions. Both the dipolar and dispersion interaction coefficients, for these three-body degenerate systems, show dependences on the geometrical configurations of the three atoms. The nonadditive interactions start to appear in second-order. To demonstrate the results and for applications, the obtained coefficients Cn are evaluated with highly accurate variationally generated nonrelativistic wave functions in Hylleraas coordinates for He(1 1S ) -He(1 1S ) -He(2 1S ) , He(1 1S ) -He(1 1S ) -He(2 1P ) , He(2 1S ) -He(2 1S ) -He(2 1P ) , and He(2 3S ) -He(2 3S ) -He(2 3P ) . The calculations are given for three like nuclei for the cases of hypothetical infinite mass He nuclei, and of real finite mass 4He or 3He nuclei. The special cases of the three atoms in equilateral triangle configurations are explored in detail, and for the cases in which one of the atoms is in a P state, we also present results for the atoms in an isosceles right triangle configuration or in an equally spaced collinear configuration. The results can be applied to construct potential energy surfaces for three helium atom systems.

  11. Terrestrial cosmogenic 3He: where are we 30 years after its discovery?

    Science.gov (United States)

    Blard, Pierre-Henri; Pik, Raphaël; Farley, Kenneth A.; Lavé, Jérôme; Marrocchi, Yves

    2016-04-01

    It is now 30 years since cosmogenic 3He has been detected for the first time in a terrestrial sample (Kurz, 1986). 3He is now a widely used geochemical tool in many fields of Earth sciences: volcanology, tectonics, paleoclimatology. 3He has the advantage to have a high "production rate" to "detection limit" ratio, allowing surfaces as young as hundred of years to be dated. Although its nuclear stability implies several limitations, it moreover represents a useful alternative to 10Be in mafic environments. This contribution is a review of the progresses that have been accomplished since this discovery, and discuss strategies to improve both the accuracy and the precision of this geochronometer. 1) Measurement of cosmogenic 3He Correction of magmatic 3He. To estimate the non-cosmogenic magmatic 3He, Kurz (1986) invented a two steps method involving crushing of phenocrysts (to analyze the isotopic ratio of the magmatic component), followed by a subsequent melting of the sample, to extract the remaining components, including the cosmogenic 3He: 3Hec = 3Hemelt -4Hemelt x (3He/4He)magmatic (1) Several studies suggested that the preliminary crushing may induce a loss of cosmogenic 3He (Hilton et al., 1993; Yokochi et al., 2005; Blard et al., 2006), implying an underestimate of the cosmogenic 3He measurement. However, subsequent work did not replicate these observations (Blard et al., 2008; Goerhing et al., 2010), suggesting an influence of the used apparatus. An isochron method (by directly melting several phenocrysts aliquots) is an alternative to avoid the preliminary crushing step (Blard and Pik, 2008). Atmospheric contamination. Protin et al. (in press) provides robust evidences for a large and irreversible contamination of atmospheric helium on silicate surfaces. This unexpected behavior may reconcile the contrasted observations about the amplitude of crushing loss. This undesirable atmospheric contamination is negligible if grain fractions smaller than 150 mm are

  12. Technic and economic viability study on exploitation of lunar 3He resource

    International Nuclear Information System (INIS)

    Deng Baiquan

    1995-01-01

    From the energetics point of view, the technic and economic viability study on exploitation of lunar 3 He for fuelling the fusion reactor burning D- 3 He has been carried out. This study is divided into the following sections: analysis of solar wind parameters and estimation of potential quantity 3 He in the lunar regolith, the cost evaluation of mining He of lunar soil; the energy cost calculation of He extraction by vacuum heating degassing during lunar day, the cost calculation of cryogenic isotopic separation 3 He/ 4 He during the lunar night, the energy cost for earth/moon transportation of liquid 3 He, the energy payback calculation of fusion power burning 3 He based lunar source, and finally the comparison of the energy multiplication with that for 235 U production of nuclear fuel and for coal mining. The comparisons of cost of electricity between D- 3 He and D-T fuel cycle for different reactor types have been discussed

  13. Angular dependence of the sup(6)Li(πsup(+),sup(3)He)sup(3)He reaction

    International Nuclear Information System (INIS)

    McParland, B.J.; Auld, E.G.; Couvert, P.

    1985-02-01

    Angular distributions of the differential cross sections for the pionic fission sup(6)Li(πsup(+),sup(3)He)sup(3)He have been measured at pion energies of 60 and 80 MeV. The differential cross section is found to decrease monotonically with cossup(2)thetasup(*) and is compared with a theoretical prediction

  14. Phase transition of two-dimensional 3He from a dilute to a dense phase

    International Nuclear Information System (INIS)

    Bhattacharyya, B.K.; Gasparini, F.M.

    1985-01-01

    We have measured the heat capacity of 3 He in films of 4 He as thin as 10 A formed on a Nuclepore filter substrate. At low temperatures, where the 3 He is in the lowest state as far as motion perpendicular to the film surface, we find that the 3 He undergoes a transition from a dilute phase to a dense phase. We have observed this transition for films of 4 He of 12.3- and 10-A thickness and for coverages of 3 He below about 0.2 atomic layers. For thicker 4 He films, and higher 3 He coverages, the 3 He remains homogeneously spread out over the surface of the 4 He. The striking characteristic of the transition is the sudden onset of linear temperature dependence with a slope which is proportional to the amount of 3 He in the calorimeter. This is consistent with the formation of islands of a dense two-dimensional phase which grows in extent proportionately to the amount of 3 He. Two puzzling aspects of our results are the lack of a significant heat-capacity jump at the transition and, based on a linear extrapolation of the data to zero temperature, a substantial amount of missing entropy

  15. Neutron scattering lengths of 3He

    International Nuclear Information System (INIS)

    Alfimenkov, V.P.; Akopian, G.G.; Wierzbicki, J.; Govorov, A.M.; Pikelner, L.B.; Sharapov, E.I.

    1976-01-01

    The total neutron scattering cross-section of 3 He has been measured in the neutron energy range from 20 meV to 2 eV. Together with the known value of coherent scattering amplitude it leads to the two sts of n 3 He scattering lengths

  16. 4f states of He2: A new spectrum of He2 in the near infrared

    International Nuclear Information System (INIS)

    Herzberg, G.; Jungen, C.

    1986-01-01

    A new spectrum of the He 2 molecule has been discovered in the region 5100--5900 cm -1 . It is identified as the 4f--3d Rydberg transition of He 2 with a weak contribution of 4d--3p in the same region. The uncoupling of l from the internuclear axis in both the triplet and the singlet system is almost complete in the 4f complex; the appropriate quantum number is N + corresponding to the rotational angular momentum of the He + 2 core. The electronic fine structure in each N + level depends on the dipole polarizability α of the core and its anisotropy as well as on the quadrupole moment Q 2 and higher moments Q 4 ,... of the core. Conversely, from the observed structure some of the quantities characterizing the core have been determined, e.g., α = 1/3(2α/sub perpendicular/+α/sub parallel/) = 2.82 +- 0.02, Q 2 = 1.39 +- 0.13, Q 4 = 0.99 +- 0.14, all in atomic units. The detailed rotational analysis of the spectrum shows that widespread perturbations occur in the triplet 4f levels, the largest affecting the N = 6,N + = 3 and N = 9,N + = 7 levels which are shifted towards higher energies by 1 and 2 cm -1 , respectively. The perturbations are clearly caused by Δl = 2 interaction with corresponding levels of 4pπ for which Orth and Ginter have found the opposite perturbations. There are no similar perturbations in the corresponding singlet levels

  17. Interaction of a 29 MeV 3He particle beam with a Cl4C vapour target

    International Nuclear Information System (INIS)

    Lleo Morilla, A.

    1963-01-01

    The interactions of a 29 MeV 3 H e particles beam on a Cl 4 C vapour target have been studied using the photographic method. differential cross-sections for the Cl( 3 He, 3 He)Cl elastic scattering and 1 2C( 3 He, α) 1 1C pick-up reaction are shown; the corresponding angular distributions in the centre-of-mass system have been compared with the predictions of optical model and A.B.M. theories. (Author) 21 refs

  18. Examination of X-ray spectra from the antiprotonic helium isotopes 3He and 4He

    International Nuclear Information System (INIS)

    Schneider, M.

    1987-05-01

    Using the high intensity antiprotonic LEAR beam at CERN (Geneva), several measurements were done to investigate the X-ray spectra of the antiprotonic Helium isotopes 3 He and 4 He. For the first time antiprotons were stopped in gases at low pressures (600, 375, 72 and 36 mbar), which permitted observations on nearly isolated atoms. A newly developed method for stopping the antiprotons in gases by means of a focusing cyclotron field surrounding the target gas was used. The field was supplied by a superconducting magnet ('cyclotron trap'). The antiprotons were tangentially injected into the cyclotron field, where they slowed down by ionising the target gas. The inhomogeneous magnetic field guided the antiprotons in spiral orbits to the magnetic center. Thus, even at low pressures a very small stopping volume could be achieved. To detect the X-rays different Si(Li)- and Ge-semiconductor detectors were used, some of which were furnished with 'guard-rings'. They were used to investigate the effects of the strong interaction between the antiproton and the nucleus in the (3d → 2p) transition in both isotopes. The analyzis of this transition permitted directly the determination of the shift and width of the 2p-level. The width of the 3d-level could be determined only indirectly using an intensity balance. The utilization of gases with different pressures permitted investigations of the pressure dependence of the antiprotonic deexcitation process. The results for the widths and shifts were compared with earlier measurements and theoretical predictions. The theory agrees only partly with the measurements. The evaluation of a complex scattering length using an optical model contradicts some of the results of calculations. (orig.) [de

  19. High resolution measurements of the He-He total scattering cross section for reduced collision energies between 0.2 and 200

    International Nuclear Information System (INIS)

    Feltgen, R.; Koehler, K.A.; Pauly, H.; Torello, F.; Vehmeyer, H.

    1974-01-01

    The energy dependence of the total scattering cross section is measured for the isotopic systems He 4 -He 4 and He 3 -He 3 using a velocity selected He primary beam and a He target in a scattering chamber maintained at 1.57 deg K. In the low energy region both systems show a pronounced atomic Ramsauer-Townsend effect. At higher energies 13 backward glory extrema in the case of He 4 -He 4 and 10 extrema for He 3 -He 3 are observed. From these extrema the energy dependence of the s-phase shift can be derived. Applying the semiclassical inversion method proposed by Miller it is possible to compute the repulsive potential in the energy range of the measurement

  20. 12C(3He,3He n)11C cross section at 910 MeV

    International Nuclear Information System (INIS)

    Aslanides, E.; Fassnacht, P.; Dellacasa, G.; Gallio, M.; Tuyn, J.W.N.

    1981-01-01

    The 12 C( 3 He, 3 He n) 11 C cross section at 910 MeV was measured by using a Ge(Li) gamma spectrometer to determine the disintegration rate and measuring the incident flux by means of a scintillator telescope. Cross sections for the production of 7 Be in C and Al and for the production of 24 Na in Al are then determined using the measured cross section as a monitor

  1. Mobilities of ions trapped on vortex lines in dilute 3He--4He solutions

    International Nuclear Information System (INIS)

    Huang, W.; Dahm, A.J.

    1976-01-01

    A model calculation of the mobility of a positive ion in the presence of 3 He atoms condensed on a vortex core is presented. Reasonable qualitative and quantitative agreement between theory and experiment is obtained, and reasons for differences are discussed. A reason for the larger mobility of the negative ion in comparison to the smaller positive ion is suggested. The contribution of vortex waves to the scattering of ions is addressed

  2. Differential osmotic pressure measurements of the concentration susceptibility of liquid 3He/4He mixtures near the lambda curve and tricritical point

    International Nuclear Information System (INIS)

    Gearhart, C.A. Jr.; Zimmermann, W. Jr.

    1979-01-01

    Values of the concentration susceptibility (partial x/partial Δ)/sub T/,P of liquid 3 He/ 4 He mixtures have been determined near the lambda curve and tricritical point from measurements of the differential osmotic pressure as a function of temperature T at four values of the 3 He mole fraction, x = 0.594, x = 0.644, x = 0.680, and x = 0.706. Here Δ = μ 3 - μ 4 is the difference between molar chemical potentials and P is the pressure. Our results for the two values of x less than the tricritical value x/sub t/ = 0.675 show pronounced peaks at the lambda transition. For 3 x 10 -4 -2 , where t equals [T - T/sub lambda/(x)]/T/sub lambda/(x), these peaks may be characterized both above and below the transition by the form (A/sub plus-or-minus//α/sub plus-or-minus/) (vertical-bart vertical-bar/sup -alpha/ +- - 1) + B/sub plus-or-minus/, with exponents α/sub plus-or-minus/ lying in the range from approx. 0.0 to approx. 0.2. Except perhaps for x -1 [T-T/sub t//T/sub t/)/vertical-barx-x/sub t//x/sub t/vertical-bar], where f and Ψ are functions determined by experiment and T/sub t/ = 0.867 K is the tricritical value of T. With the aid of this scaling relationship, the behavior of (partialx/partialΔ)/sub T/,P along curves of constant Δ near the lambda curve has been constucted from our data at constant x

  3. Spin effects in medium-energy electron-3He scattering

    International Nuclear Information System (INIS)

    van den Brand, J.F.J.; Alarcon, R.; Bauer, T.

    1998-01-01

    New physics can be accessed by scattering polarized electrons from a polarized 3 He internal gas target. It is discussed how the asymmetries for the reactions 3 vector He(vector e,e'), 3 vector He(vector e,e'p), 3 vector He(vector e,e'n), 3 vector He(vector e,e'd), and 3 vector He(vector e,e'pn) may provide precise information on the S' and the D-wave parts of the 3 He ground-state wave function, the neutron form factors, and the role of spin-dependent reaction mechanism effects. The experiment uses up to 900 MeV (polarized) electrons from the AmPS storage ring in Amsterdam, Netherlands, in combination with large acceptance electron and hadron detectors. (orig.)

  4. A liquid He-3 target system for use at intermediate energies

    International Nuclear Information System (INIS)

    Hassell, D.K.; Abegg, R.; Murdoch, B.T.; van Oers, W.J.H.; Soukup, J.

    1981-04-01

    A liquid 3 He target system with remote instrumentation and handling capabilities has been developed for experiments using the 180-525 MeV TRIUMF cyclotron. Helium-3 gas is liquefied by means of a 4 He cryostat into a cylindrical target cell (4.4 cm diameter, 1.6 cm thick) and maintained during operation at approximately 1.6 K. This provides an areal target density of approximately 2.7 x 10 22 He-3 nuclei/cm 2 (128 mg/cm 2 ), suitable for intermediate energy proton scattering. (author)

  5. The effect of He and swift heavy ions on nanocrystalline zirconium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Janse van Vuuren, A., E-mail: arnojvv@gmail.com [Centre for HRTEM, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Centre for HRTEM, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Skuratov, V.A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Uglov, V.V. [Belarusian State University, Minsk (Belarus); Petrovich, S. [VINCA Institute of Nuclear Sciences, Belgrade University, Belgrade (Serbia)

    2014-05-01

    Recent studies have shown that swift heavy ion irradiation may significantly modulate hydrogen and helium behaviour in some materials. This phenomenon is of considerable practical interest for ceramics in general and also for candidate materials for use as inert matrix fuel hosts. These materials will accumulate helium via (n, α) reactions and will also be subjected to irradiation by fission fragments. Cross-sectional transmission electron microscopy and scanning electron microscopy was used to study nanocrystalline ZrN irradiated with 30 keV He to fluences between 10{sup 16} and 5 × 10{sup 16} cm{sup −2}, 167 MeV Xe to fluences between 5 × 10{sup 13} and 10{sup 14} cm{sup −2} and also 695 MeV Bi to a fluence of 1.5 × 10{sup 13} cm{sup −2}. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C and were analysed using SEM, XTEM and selected area diffraction. The results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. SEM and XTEM analysis of He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.

  6. The effect of He and swift heavy ions on nanocrystalline zirconium nitride

    International Nuclear Information System (INIS)

    Janse van Vuuren, A.; Neethling, J.H.; Skuratov, V.A.; Uglov, V.V.; Petrovich, S.

    2014-01-01

    Recent studies have shown that swift heavy ion irradiation may significantly modulate hydrogen and helium behaviour in some materials. This phenomenon is of considerable practical interest for ceramics in general and also for candidate materials for use as inert matrix fuel hosts. These materials will accumulate helium via (n, α) reactions and will also be subjected to irradiation by fission fragments. Cross-sectional transmission electron microscopy and scanning electron microscopy was used to study nanocrystalline ZrN irradiated with 30 keV He to fluences between 10 16 and 5 × 10 16 cm −2 , 167 MeV Xe to fluences between 5 × 10 13 and 10 14 cm −2 and also 695 MeV Bi to a fluence of 1.5 × 10 13 cm −2 . He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C and were analysed using SEM, XTEM and selected area diffraction. The results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. SEM and XTEM analysis of He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  8. Strangeness production in antiproton annihilation at rest on sup 3 He, sup 4 He and sup 20 Ne

    Energy Technology Data Exchange (ETDEWEB)

    Balestra, F. (Cagliari Univ. (Italy). Dipt. di Scienze Fisiche Istituto Nazionale di Fisica Nucleare, Cagliari (Italy)); Batusov, Yu.A.; Falomkin, I.V.; Pontecorvo, G.B.; Rozhdestvensky, A.M.; Sapozhnikov, M.G.; Tretyak, V.I. (Joint Inst. for Nuclear Research, Dubna (USSR)); Bendiscioli, G.; Filippini, V.; Rotondi, A.; Salvini, P.; Venaglioni, A. (Pavia Univ. (Italy). Dipt. di Fisica Nucleare e Teorica Istituto Nazionale di Fisica Nucleare, Pavia (Italy)); Bossolasco, S.; Bussa, M.P.; Busso, L.; Fava, L.; Ferrero, L.; Panzieri, D.; Piragino, G.; Tosello, F. (Turin Univ. (Italy). Ist. di Fisica Generale Istituto Nazionale di Fisica Nucleare, Turin (Italy)); Breivik, F.O.; Danielsen, K.M.; Jacobsen, T.; Soerensen, S.O. (Oslo Univ. (Norway). Physics Dept.); Guaraldo, C.; Maggiora, A. (Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati); Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.M. (Bergen Univ. (Norway). Dept. of Physics); Lodi Rizzini,

    1991-05-13

    New data are reported on antiproton annihilations at rest with production of {Lambda} and K{sub S}{sup 0}, using a streamer chamber with {sup 3}He, {sup 4}He and {sup 20}Ne as gas targets. The data include {Lambda}, K{sub S}{sup 0}, {Lambda}K{sub S}{sup 0} and K{sub S}{sup 0}K{sub S}{sup 0} production rates and momentum distributions, {pi}{sup -} momentum spectra, mean numbers of charged particles generally and of negatively charged particles separately for different reaction channels. The yields are compared to simple combinatorial calculations based on the extreme assumptions of {Lambda} production via B=1 or via B=0 (anti K rescattering) annihilations. {Lambda} and K{sub S}{sup 0} momentum spectra are compared to simple model calculations where B=0 and B=1 annihilations with and without final-state interactions are considered. A review of existing data on {Lambda} and K{sub S}{sup 0} production is presented, showing the dependence on the anti p momentum and on the mass number of the target. (orig.).

  9. Fifth sound in superfluid 4He below 1 K

    International Nuclear Information System (INIS)

    Williams, G.A.; Rosenbaum, R.

    1979-01-01

    Fifth-sound propagation has been studied in He II adsorbed on large-diameter alumina (Al 2 O 3 ) powder grains below 1 K. The velocity of the fifth-sound mode in 4 He remains in good agreement with the theoretical value c 2 5 =rho/sub n//rhoc 2 2 . Using tabulated values for rho/sub n//rho, values of the second-sound velocity are obtained

  10. Ab initio study of He-He interactions in homogeneous electron gas

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinlong; Niu, Liang-Liang; Zhang, Ying, E-mail: zhyi@buaa.edu.cn

    2017-02-15

    Highlights: • Helium atoms interact via the He induced Friedel oscillations of electron densities. • He-He global binding energy minimum of ∼−0.09 eV is reached at an optimal electron density of 0.04 e/Å{sup 3}, corresponding to an optimal He-He separation of ∼1.7 Å. • The present results can qualitatively interpret the well-known He self-trapping behavior in metals. - Abstract: We have investigated the immersion energy of a single He and the He-He interactions in homogeneous electron gas using ab initio calculations. It is found that He dislikes electrons and He-He interact via the He induced Friedel oscillations of electron densities. A critical electron density at which the global binding energy extremum shifts from the first minimum to the second one is identified. We also discover that the He-He global binding energy minimum of ∼−0.09 eV is reached at an optimal electron density of 0.04 e/Å{sup 3}, corresponding to an optimal He-He separation of ∼1.7 Å. Further, the He atoms are found to gain a trivial amount of 2s and 2p states from the free electrons, inducing a hybridization between the He s- and p-states. The present results can qualitatively interpret the well-known He self-trapping behavior in metals.

  11. Determination of the π3He3H coupling constant

    International Nuclear Information System (INIS)

    Nichitiu, F.; Sapozhnikov, M.G.

    1977-01-01

    Despersion relations for the real part of the antisymmetric amplitude of the π +-3 He scattering have been used in order to determine the π 3 He 3 H coupling constant. The coupling constant value determined by this method is larger than the elementary pion-nucleon coupling constant, but is in good agreement with the value obtained by another method. The obtained value is f 2 sub(π 3 He 3 H) = 0.12+-0.01. Shown is the importance of using the Coulomb corrections for dispersion relation calculations because the value of π 3 He 3 H coupling constant obtained with corrected total cross sections is larger by about 0.014 than the one obtained without these corrections. The best energy ranges for future π 3 He experiments are commented

  12. Opportunities for Polarized He-3 in RHIC and EIC

    Energy Technology Data Exchange (ETDEWEB)

    Aschenauer E.; Deshpande, A.; Fischer, W.; Derbenev, S.; Milner, R.; Roser, T.; Zelenski, A.

    2011-10-01

    The workshop on opportunities for polarized He-3 in RHIC and EIC was targeted at finding practical ways of implementing and using polarized He-3 beams. Polarized He-3 beams will provide the unique opportunity for first measurements, i.e, to a full quark flavor separation measuring single spin asymmetries for p{sup +}, p{sup -} and p{sup 0} in hadron-hadron collisions. In electron ion collisions the combination of data recorded with polarized electron proton/He-3 beams allows to determine the quark flavor separated helicity and transverse momentum distributions. The workshop had sessions on polarized He-3 sources, the physics of colliding polarized He-3 beams, polarimetry, and beam acceleration in the AGS Booster, AGS, RHIC, and ELIC. The material presented at the workshop will allow making plans for the implementation of polarized He-3 beams in RHIC.

  13. Photodetachment of metastable He-

    International Nuclear Information System (INIS)

    Thompson, J.S.; Dellwo, J.; Compton, R.N.

    1990-01-01

    A crossed-beams apparatus has been used to measure angular distributions and cross sections for photoelectron detachment from metastable He - . Energy- and angle-resolved electron spectroscopy was used to investigate the spectral dependences of the angular distribution of the photoelectrons. The angular distributions along with photoelectron yield measurements were used to determine the cross sections for photodetachment of He - (2 4 P) via the energy resolved He(2 3 P) and He(2 3 S) exit channels. The precision of the cross section measurements was enhanced by exploiting the kinematic effects associated with detachment from a fast beam source. Calculated cross sections for the photodetachment of H - were used to establish an absolute scale for the He - cross section measurements

  14. Oscillatory behaviour of Rydberg state total cross sections in the collisions Ne+-He and He+-Ne

    International Nuclear Information System (INIS)

    Andresen, B.; Jensen, K.; Veje, E.

    1976-01-01

    The Ne + -He and He + -Ne collisions have been studied by means of optical spectrometry in the projectile energy range 10-150 keV. Very similar and regular oscillations in the Rydberg state total cross sections are found for HeI in both collisions and for singlet as well as triplet excitation. These oscillations are well described by the Rosenthal model. The HeI 4d sup(1,3)D states display two superimposed oscillations for center-of-mass collision energies above 6.4 keV. This is interpreted as the opening of a third exit channel, believed to be the HeI 4f sup(1,3)F. No, or very little structure is found in the Rydberg state total cross sections for HeII, NeI, NeII and NeIII levels. (Auth.)

  15. Quark substructure approach to 4He charge distribution

    International Nuclear Information System (INIS)

    Wilets, L.; Alberg, M.A.; Pepin, S.; Stancu, F.; Carlson, J.; Koepf, W.

    1997-01-01

    We present a study of the 4 He charge distribution based on realistic nucleonic wave functions and incorporation of quark substructure. Any central depression of the proton point density seen in modern four-body calculations is too small by itself to lead to a correct description of the charge distribution of 4 He if folded with a fixed proton size parameter, as is usually done. We utilize six-quark structures calculated in the chromodielectric model for N-N interactions to find a swelling of the proton size as the internucleon distance decreases. This swelling is a result of the short-range dynamics in the N-N system. Using the independent pair approximation, the corresponding charge distribution of the proton is folded with the two-nucleon distribution generated from Green's function Monte Carlo calculations of the 4 He nucleonic wave function. We obtain a reasonably good fit to the experimental charge distribution of 4 He. Meson-exchange currents have not been included. copyright 1997 The American Physical Society

  16. Towards the observation of the magnetic structure of solid 3He

    International Nuclear Information System (INIS)

    Rufin, D.

    1982-03-01

    Experiments involving neutron scattering by 3 He for which thermalization problems have been solved, along with the development of novel measurement techniques (density, magnetization, temperature) by polarized neutron transmission, crystallization experiments with 3 He and 4 He: a single crystal of helium have been obtained within a sintered metal in which the pore size is less than a micron are presented [fr

  17. Surface study of liquid 3He using surface state electrons

    International Nuclear Information System (INIS)

    Shirahama, K.; Ito, S.; Suto, H.; Kono, K.

    1995-01-01

    We have measured the mobility of surface state electrons (SSE) on liquid 3 He, μ 3 , aiming to study the elementary surface excitations of the Fermi liquid. A gradual increase of μ 3 below 300 mK is attributed to the scattering of electrons by ripplons. Ripplons do exist in 3 He down to 100 mK. We observe an abrupt decrease of μ 3 , due to the transition to the Wigner solid (WS). The dependences of the WS conductivity and mobility on temperature and magnetic field differ from the SSE behavior on liquid 4 He

  18. Super enrichment of Fe-group nuclei in solar flares and their association with large 3He enrichments

    International Nuclear Information System (INIS)

    Anglin, J.D.; Dietrich, W.F.; Simpson, J.A.

    1977-01-01

    ''Fe''/He ratios at approximately 2 MeV/n have been measured in 60 solar flares and periods of enhanced fluxes during the interval 1972-1976. The observed ditribution of ratios is extremely wide with values ranging from approximately 1 to more than 1000 times the solar abundance ratio. In constrast, most of the CHO/He ratios for the same flares lie within a factor 2 of the observed mean value of 2 x 10 -2 . While experimental limitations prevent a complete correlation study of Fe-group and 3 He abundances, comparison of flares with large Fe enrichments with flares with large 3 He enrichments for the period 1969-1976 shows that a 3 He-rich flare is also likely to be rich in iron. We feel that the association of 3 He and Fe enrichments may be explained by a two-stage process in which a preliminary enrichment of heavy nuclei precedes the preferential acceleration of ambient 3 He. Nuclear interactions are ruled out as the principal source of the enriched 3 He. (author)

  19. Spin Superfluidity and Magnone BEC in He-3

    Science.gov (United States)

    Bunkov, Yury

    2011-03-01

    The spin superfluidity -- superfluidity in the magnetic subsystem of a condensed matter -- is manifested as the spontaneous phase-coherent precession of spins first discovered in 1984 in 3 He-B. This superfluid current of spins -- spin supercurrent -- is one more representative of superfluid currents known or discussed in other systems, such as the superfluid current of mass and atoms in superfluid 4 He; superfluid current of electric charge in superconductors; superfluid current of hypercharge in Standard Model of particle physics; superfluid baryonic current and current of chiral charge in quark matter; etc. Spin superfluidity can be described in terms of the Bose condensation of spin waves -- magnons. We discuss different states of magnon superfluidity with different types of spin-orbit coupling: in bulk 3 He-B; magnetically traped `` Q -balls'' at very low temperatures; in 3 He-A and 3 He-B immerged in deformed aerogel; etc. Some effects in normal 3 He can also be treated as a magnetic BEC of fermi liquid. A very similar phenomena can be observed also in a magnetic systems with dinamical frequensy shift, like MnC03 . We will discuss the main experimental signatures of magnons superfluidity: (i) spin supercurrent, which transports the magnetization on a macroscopic distance more than 1 cm long; (ii) spin current Josephson effect which shows interference between two condensates; (iii) spin current vortex -- a topological defect which is an analog of a quantized vortex in superfluids, of an Abrikosov vortex in superconductors, and cosmic strings in relativistic theories; (iv) Goldstone modes related to the broken U (1) symmetry -- phonons in the spin-superfluid magnon gas; etc. For recent review see Yu. M. Bunkov and G. E. Volovik J. Phys. Cond. Matter. 22, 164210 (2010) This work is partly supported by the Ministry of Education and Science of the Russian Federation (contract N 02.740.11.5217).

  20. Electric dipole moment of 3He

    International Nuclear Information System (INIS)

    Avishai, Y.; Fabre de la Ripelle, M.

    1987-01-01

    The contribution of CP violating nucleon-nucleon interaction to the electric dipole moment of 3 He is evaluated following a recent proposal for its experimental detection. Two models of CP violating interactions are used, namely, the Kobayashi-Maskawa mechanism and the occurrence of the Θ term in the QCD lagrangian. These CP violating interactions are combined with realistic strong nucleon-nucleon interactions to induce a CP forbidden component of the 3 He wave function. The matrix element of the electric dipole operator is then evaluated between CP allowed and CP forbidden components yielding the observable electric dipole moment. Using the parameters emerging from the penguin terms in the Kobaysashi-Maskawa model we obtain a result much larger than the electric dipole moment of the neutron in the same model. On the other hand, no enhancement is found for the Θ-term mechanism. A possible explanation for this difference is discussed. Numerical estimates can be given only in the Kobayashi-Maskawa model, giving d( 3 He) ≅ 10 30 e . cm. In the second mechanism, the estimate give d ( 3 He) ≅ 10 16 anti Θ. (orig.)

  1. {sup 3}He detector analysis of some special shielding materials

    Energy Technology Data Exchange (ETDEWEB)

    Avdic, S; Pesic, M [Boris Kidric, Institute of Nuclear Sciences, Beograd (Yugoslavia); Marinkovic, P [ETF Belgrade Univ. (Yugoslavia)

    1990-07-01

    The shielding properties of commercial materials of reactor Experiments, Inc. (R/X) were analyzed at the facility which includes bare heavy water experimental reactor RB with external neutron converter ENC, The fast neutron spectrum measurements in energy range from 1 MeV to 10 MeV was performed using ORTEC semiconductor neutron detector with He{sup 3} in diode coincidence arrangement. The neutron spectra have been evaluated from measured pulse-height distribution using numerical code HE3 for computation of detector efficiency in a collimated neutron beam. The neutron dose rates behind ENC with and without sample R/X material were determined using cubic spline interpolation routine for calculating the corresponding flux-dose rate conversion factors. Satisfactory shielding properties of the examined material in a fast neutron field in measurements and calculations are demonstrated. (author)

  2. Backward elastic p3He-scattering and high momentum components of 3He wave function

    International Nuclear Information System (INIS)

    Uzikov, Yu.N.

    1998-01-01

    It is shown that owing to a dominance of np-pair transfer mechanism of backward elastic p 3 He-scattering for incident proton kinetic energies T p > 1 GeV the cross section of this process is defined mainly by the values of the Faddeev component of the wave function of 3 He nucleus, φ 23 (q 23 , p 1 ), at high relative momenta q 23 > 0.6 GeV/c of the NN-pair in the 1 S 0 -state and at low spectator momenta p 1 ∼ 0 - 0.2 GeV/c

  3. A validation of the 3H/3He method for determining groundwater recharge

    Science.gov (United States)

    Solomon, D. K.; Schiff, S. L.; Poreda, R. J.; Clarke, W. B.

    1993-09-01

    Tritium and He isotopes have been measured at a site where groundwater flow is nearly vertical for a travel time of 100 years and where recharge rates are spatially variable. Because the mid-1960s 3H peak (arising from aboveground testing of thermonuclear devices) is well-defined, the vertical groundwater velocity is known with unusual accuracy at this site. Utilizing 3H and its stable daughter 3He to determine groundwater ages, we compute a recharge rate of 0.16 m/yr, which agrees to within about 5% of the value based on the depth of the 3H peak (measured both in 1986 and 1991) and two-dimensional modeling in an area of high recharge. Zero 3H/3He age occurs at a depth that is approximately equal to the average depth of the annual low water table, even though the capillary fringe extends to land surface during most of the year at the study site. In an area of low recharge (0.05 m/yr) where the 3H peak (and hence the vertical velocity) is also well-defined, the 3H/3He results could not be used to compute recharge because samples were not collected sufficiently far above the 3H peak; however, modeling indicates that the 3H/3He age gradient near the water table is an accurate measure of vertical velocities in the low-recharge area. Because 3H and 3He have different diffusion coefficients, and because the amount of mechanical mixing is different in the area of high recharge than in the low-recharge area, we have separated the dispersive effects of mechanical mixing from molecular diffusion. We estimate a longitudinal dispersivity of 0.07 m and effective diffusion coefficients for 3H (3HHO) and 3He of 2.4×10-5 and 1.3×10-4 m2/day, respectively. Although the 3H/3He age gradient is an excellent indicator of vertical groundwater velocities above the mid-1960s 3H peak, dispersive mixing and diffusive loss of 3He perturb the age gradient near and below the 3H peak.

  4. A polarized solid {sup 3}He target for neutron transmission experiments

    Energy Technology Data Exchange (ETDEWEB)

    Keith, C.D. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Gould, C.R. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Haase, D.G. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Huffman, P.R. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Roberson, N.R. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Seely, M.L. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Wilburn, W.S. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    1995-04-01

    We describe the construction and operation of a solid {sup 3}He polarized nuclear target which we have used for measurements of the spin dependence of the n-{sup 3}He interaction at MeV energies. The target, which contains 0.4 mole of {sup 3}He was polarized to 38% at 12 mK in a field of 7 T. The target is suitable for nuclear physics measurements which are insensitive to the large magnetic field and produce beam heating of tenths of microwatts.We discuss refinements and paths to improved solid {sup 3}He targets at higher polarizations and lower fields. ((orig.)).

  5. Thermal convection and nonlinear effects of a superfluid 3He-4He mixture in a porous medium

    International Nuclear Information System (INIS)

    Chien, L.C.L.

    1986-01-01

    The convective instability of one-component classical fluids in a porous medium confined between two unbounded slabs was studied. This system behaves like a high Prandtl number bulk fluid. It has boundary conditions similar to the stress-free boundary conditions of bulk one-component classical fluids. Both the amplitude expansion method and the Galerkin method were used to investigate the nonlinear steady convection. Two dimensional rolls are the only stable motion at the onset of convection. Beyond threshold, the steady convection rolls become unstable to formation of cross-roll and zigzag instabilities. Applying the phase-dynamics approach for the zigzag instability, the author obtained the diffusion coefficient D, which can signal the onset of instability. Also investigated was the convective instability of superfluid 3 He- 4 He mixtures in porous media. Assuming no interaction between the average superflow and the porous medium and treating the normal flow in the equation of motion like a classical fluid in a porous medium, it was found that the superfluid mixtures in a porous medium. To investigate the effects of a lateral boundary, the convective instability of classical one-component fluids in porous media inside a box was studied. The zigzag instability does not exist because of the boundary conditions at the side of the box

  6. Study of the excited {Delta} resonance ways of decay in {sup 4}He and other nuclei with the ({sup 3}He,T) reaction at 2 GeV; Etude des voies de decroissance de la resonance {Delta} excitee dans l`{sup 4}He et d`autres noyaux par la reaction ({sup 3}He,T) a 2 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Tarle-Rousteau, S

    1995-05-10

    This thesis describes the ({sup 3}He,t) experiment carried out at 2 GeV at the Saturne National Laboratory (CEA Saclay, France) on {sup 1}H, {sup 2}H, {sup 4}He, {sup 12}C and {sup 208}Pb targets. The charged particles (pions and/or protons) from the {Delta} resonance deexcitation are detected in coincidence with triton using the Diogene large angle detector. New informations are obtained on the ways of {Delta} resonance decay in nuclei. Three modes of decay are investigated: the quasi-free decay, the {Delta}N into NN absorption and the coherent pions production. Modifications of {Delta} resonance properties in nuclei with respect to those of free {Delta} are analysed using the experimental results about pions diffusion, photons absorption, charge exchange reaction and {Delta}-hole model conclusions. The quasi-deuteron absorption process on {sup 4}He is studied using a Monte-Carlo simulation. Coherent pions production is also analysed in detail on {sup 4}He and {sup 12}C target nuclei. The process is very sensitive to {Delta}-hole correlations involved in the longitudinal spin canal which shifts the nucleus response in the {Delta} resonance region towards the low transferred energies. (J.S.). 85 refs., 72 figs., 10 tabs., 1 annexe.

  7. Broadening of some He I and He II lines in a plasma

    International Nuclear Information System (INIS)

    Einfeld, D.; Sauerbrey, G.

    1975-01-01

    The broadening of the He I and He II lines was investigated in a wall-stabilized discharge (duration approximately 500 μs, Ne approximately 2 x 10 16 cm -3 , T approximately 37,000 K). The xi factor calculated by Kriener and Schlueter could be used for the Ne determination from the continuum radiation. For the line width of the He I line 501.4 nm, the discrepancy of a factor 1.7 to Griem, Baranger, Kolb, Oertel reported by Kusch was confirmed. Also confirmed was the theoretical dependence of the distance between the group peaks on the electron densities for the He I lines 447.1 nm and 492.1 nm, first reported by Griem and Barnard et al. The line widths of the He II lines 320.3 nm and 408.6 nm are between the values given by Kepple and Griem, and Griem, Kolb, Shen. (orig./AK) [de

  8. Effects of magnetic impurity scattering on superfluid 3He in aerogel

    Science.gov (United States)

    Aoyama, Kazushi; Ikeda, Ryusuke

    2009-02-01

    We investigate impurity effects on superfluid 3He in aerogel whose surface is not coated with 4He, different from most experimental situations. In systems with no 4He coating, spins of solid 3He absorbed on the aerogel surface are active and interact with spins of quasiparticles relevant to superfluidity and, for this reason, such an aerogel is treated as magnetic scatterers. It is found that, in the ABM pairing state affected by magnetic scatterings, not only the l-vector but also the d-vector has no long-ranged orientational order, and that the strong-coupling correction due to impurity scatterings is less suppressed than that in the nonmagnetic case, implying an expansion of the A-like phase region.

  9. Pionic annihilation of antiprotons stopped on sup 3 He

    Energy Technology Data Exchange (ETDEWEB)

    Bendiscioli, G.; Filippini, V.; Rotondi, A.; Salvini, P.; Venaglioni, A. (Pavia Univ. (Italy). Dipt. di Fisica Nucleare e Teorica Istituto Nazionale di Fisica Nucleare, Pavia (Italy)); Bossolasco, S.; Bussa, M.P.; Busso, L.; Fava, L.; Ferrero, L.; Maggiora, A.; Panzieri, D.; Piragino, G.; Piragino, R.; Tosello, F. (Turin Univ. (Italy). Ist. di Fisica Generale Istituto Nazionale di Fisica Nucleare, Turin (Italy)); Batusov, Yu.A.; Falomkin, I.V.; Pontecorvo, G.B.; Rozhdestvensky, A.M.; Sapozhnikov, M.G.; Tretyak, V.I. (Joint Inst. for Nuclear Research, Dubna (USSR)); Guaraldo, C. (Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati); Lodi Rizzini, E. (Brescia Univ. (Italy). Dipt. di Automazione Industriale Istituto Nazionale di Fisica Nucleare, Turin (Italy)); Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.M. (Bergen Univ. (Norway). Dept. of Physics); Breivik, F.O.; Jacobsen, T.; Soerensen, S.O. (Oslo Univ. (Norway). Physics Dept.); Balestra

    1990-11-26

    The pionic annihilation of antiprotons stopped on {sup 3}He nuclei in a self-shunted streamer chamber exposed to the antiproton beam of LEAR is studied. The data concern charged-particle multiplicity distributions, branching ratios for different final states, the probability of final-state interaction, {pi}{sup -}, {pi}{sup +}, p and d momentum spectra, like and unlike pion angular correlations, {pi} and other charged-particle angular correlations. The comparison of the {sup 3}He data with those obtained on {sup 1}H, {sup 2}H and {sup 4}He does not reveal relevant effects due to the increase of the nucleon number; the small differences can be seen as due to a weak final-state interaction. (orig.).

  10. Moisture distribution measurements in adhesive-bonded composites using the D (3He,p)4 He reaction

    International Nuclear Information System (INIS)

    Schulte, R.L.; Deiasi, R.J.

    1981-01-01

    Adhesive bonding of composite materials for many aircraft components offers a distinct advantage in weight and cost reduction compared to similar structures that have been joined by riveting. However, the long term performance of adhesive-bonded components depends on the degree and rate of moisture absorption by the adhesive in the service environment. To investigate the rate and the mechanism of water transport in adhesive-bonded composite materials, a nuclear reaction analysis method based on the D( 3 He,p) 4 He reaction is used to measure the moisture distributions. Samples of graphite/epoxy composite materials were bonded with an epoxy adhesive and isothermally conditioned in a controlled D 2 O environment at 70% relative humidity and 77 0 C for various exposure times. The moisture profiles were measured along the adhesive (adhesive scan) as well as through the thickness of the bonded joint (transverse scan). The dimensions of the probing beam were 125 μm x 125 μm for the adhesive scan and 25 μ x 200 μm for the transverse scan. Absolute deuterium concentrations were determined by comparison of the proton yield from the composite/adhesive to that from reference standards. Calculations from diffusion models of water transport based on parameters determined from bulk measurement techniques are compared to the measured profile and the agreement indicates that classical Fickian diffusion describes the transport of moisture in these materials

  11. HD 185330 — chemically peculiar 3He star in the Kepler field

    Science.gov (United States)

    Niemczura, E.; Vennes, S.; Różański, T.; Pigulski, A.; Hełminiak, K.; Lehmann, H.

    2018-01-01

    We analyzed high-resolution spectra of the chemically peculiar 3He star HD 185330. We determined its atmospheric parameters (Teff, log g, ξ) and constrained its rotation velocity and abundance pattern. In particular, we found a large (×100) phosphorus abundance excess and evidence of 3He and 4He abundance stratification in the atmosphere.

  12. Dielectric Constant Measurements of Solid 4He

    Science.gov (United States)

    Yin, L.; Xia, J. S.; Huan, C.; Sullivan, N. S.; Chan, M. H. W.

    2011-03-01

    Careful measurements of the dielectric properties of solid 4He have been carried out down to 35 mK, considerably lower than the temperature range of previous studies. The sample was prepared from high purity gas with 3He concentrations of the order of 200 ppb and were formed by the blocked capillary method. The molar volume of the sample was 20.30 cm3. The dielectric constant of the samples was found to be independent of temperature down to 120 mK before showing a continuous increase with decreasing temperature and saturating below 50 mK. The total increase in ɛ is 2 parts in 10-5. The temperature dependence of ɛ mimics the increase in the resonant frequency found in the torsional oscillator studies and also the increase found in the shear modulus measurements.

  13. 3He release characteristics of metal tritides and scandium--tritium solid solutions

    International Nuclear Information System (INIS)

    Perkins, W.G.; Kass, W.J.; Beavis, L.C.

    1975-01-01

    Tritides of such metals as scandium, titanium, and erbium are useful materials for determining the effects of helium accumulation in metallic solids, for example, CTR first wall materials. Such effects include lattice strain and gross deformation, as reported elsewhere, which are related to 3 He retention and ultimate release. Long term gas release studies have indicated that, during the early life of a metal ditritide, a large fraction of the 3 He is retained in the solid. At more advanced ages (2 to 4 years, depending on the parent metal), the 3 He release rate becomes comparable to the generation rate. Statistical analysis of the data indicates that the acceleration in 3 He release rate depends on accumulated 3 He concentration rather than strictly on age. 3 He outgassing results are presented for thin films of ScT 2 , TiT 2 , and ErT 2 , and the critical 3 He concentrations are discussed in terms of a percolation model. Phase transformations which occur on tritide formation cast some doubt on the validity of extrapolating results obtained for metal tritides to predictions regarding the accumulation of helium in metals. Scandium is unique among the early transition and rare-earth metals in that the metal exhibits a very high room temperature tritium solubility (T/Sc = 0.4) with no phase transformation. Indeed, even the lattice parameters of the hcp scandium lattice are only minimally changed by tritium solution, and we have succeeded in obtaining single crystal ScT 0 . 3 samples in two crystallographic orientations. Using a very sensitive technique, we have measured 3 He emission from both these samples, as well as from fine-grained thin film scandium-tritium solid solution samples (ScT 0 . 3 - 0 . 4 ). The fine-grained film samples release 3 He at 2 to 3 percent of the generation rate, while the emission rate from the single-crystal samples is approximately 0.05 percent of the generation rate, indicating a strong grain size effect

  14. The construction of a Pomeranchuk cell driven by a 4He-circulating dilution refrigerator and some related experiments

    International Nuclear Information System (INIS)

    Brandt, B. van den.

    1981-01-01

    This thesis deals with some investigations at very low temperatures in which a 4 He-circulating 3 He- 4 He dilution refrigerator and a Pomeranchuk cooling device are used. The main theme is the design and construction of a special device, a Pomeranchuk cell that is precooled and pressurized with a 4 He-circulating 3 He- 4 He dilution refrigerator, that can be used to obtain a lowest temperature of the order of 1.1 mK. Furthermore, some details of the working of such a dilution refrigerator and some properties of 3 He- 4 He mixtures at high pressures were investigated. (Auth.)

  15. 3He release characteristics of metal tritides and scandium--tritium solid solutions

    International Nuclear Information System (INIS)

    Perkins, W.G.; Kass, W.J.; Beavis, L.C.

    1976-01-01

    Tritides of such metals as Sc, Ti, and Er are useful materials for determining the effects of He accumulation in metallic solids, for example, CTR first wall materials. Such effects include lattice strain and gross deformation which are related to 3 He retention and ultimate release. Long term gas release studies have indicated that, during the early life of a metal ditritide, a large fraction of the 3 He is retained in the solid. At more advanced ages, the 3 He release rate becomes comparable to the generation rate. Statistical analysis of the data indicates that the acceleration in 3 He release rate depends on accumulated 3 He concentration rather than strictly on age. 3 He outgassing results are presented for thin films of ScT 2 , TiT 2 , and ErT 2 , and the critical 3 He concentrations are discussed in terms of a percolation model. Phase transformations which occur on tritide formation cast some doubt on the validity of extrapolating results obtained for metal tritides to predictions regarding the accumulation of helium in metals. Sc is unique among the early transition and rare-earth metals in that the metal exhibits a very high room temperature T solubility (T/Sc = 0.4) with no phase transformation. Indeed, even the lattice parameters of the hcp Sc lattice are only minimally changed by T solution. Single crystal ScT/sub 0.3/ samples in two crystallographic orientations were obtained. Using a very sensitive technique, 3 He emission was measured from both these samples, as well as from fine-grained thin film Sc--T solid solution samples (ScT/sub 0.3-0.4/). The fine-grained film samples release 3 He at 2-3 percent of the generation rate, while the emission rate from the single-crystal samples is approximately 0.05 percent of the generation rate, indicating a strong grain size effect

  16. Crossed molecular beam-tunable laser determination of velocity dependence of intramultiplet mixing: K(4p2P1/2)+He →K(4p2P3/2)+He

    International Nuclear Information System (INIS)

    Anderson, R.W.; Goddard, T.P.; Parravano, C.; Warner, J.

    1976-01-01

    The velocity dependence of intramultiplet mixing, K(4p 2 P 1 / 2 ) +He→K(4p 2 P 3 / 2 )+He, has been measured over the relative velocity range v=1.3--3.4 km/sec. The cross section appears to fit a linear function Q (v) =A (v-v 0 ), where a=6.3 x 10 -4 A 2 and v 0 = 7.9 x 10 4 cm/sec. The value of A is obtained by normalization to the literature thermal average cross section. The intramultiplet mixing theory of Nikitin is modified to yield Q (v) for the process. The modified theory correctly exhibits detailed balancing, and it is normalized to provide a very good fit to the observed Q (v). The magnitude of the normalization factor, however, is larger than that predicted from recent pseudopotential calculations of the excited state potentials. The temperature dependence of intramultiplet mixing is predicted. The use of laser polarization to determine the m/subj/ dependence of the process K(4p 2 P 3 / 2 +He→K(4p 2 P 1 / 2 )+He and other collision processes of excited 2 P 3 / 2 states is examined

  17. Measurement of the polarized neutron---polarized 3He total cross section

    International Nuclear Information System (INIS)

    Keith, C.D.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Huffman, P.R.; Roberson, N.R.; Tornow, W.; Wilburn, W.S.

    1995-01-01

    The first measurements of polarized neutron--polarized 3 He scattering in the few MeV energy region are reported. The total cross section difference Δσ T for transversely polarized target and beam has been measured for neutron energies between 1.9 and 7.5 MeV. Comparison is made to predictions of Δσ T using various descriptions of the 4 He continuum. A brute-force polarized target of solid 3 He has been developed for these measurements. The target is 4.3x10 22 atoms/cm 2 thick and is polarized to 38% at 7 Telsa and 12 mK. copyright 1995 American Institute of Physics

  18. The scattering of polarized deuterons on 3He between 10 and 17 MeV

    International Nuclear Information System (INIS)

    Ohlsen, G.G.; Jarmie, N.; Haglund, R.H. Jr.; Brown, R.E.; Schmelzbach, P.A.

    1978-01-01

    Using the LASL polarized beam facility, the cross section and vector and tensor analysing powers for the 3 He(d vector,d) 3 He and 3 He(d vector,p) 4 He reactions have been measured in a large angular range at energies between 10 and 17 MeV. (orig./WL) [de

  19. HE3 outgassing from four working palladium and uranium beds

    International Nuclear Information System (INIS)

    Souers, P. C.; Coronado, P. R.; Fearon, F. M.; Garza, R. G.; Shaw , J. F.; Stump, R. K.; Tsugawa, R. T.

    1988-01-01

    The He 3 output from two palladium and two uranium beds storing T 2 and D-T was studied as a function of time. Three of the beds were started new and watched for a year; the fourth bed was twelve years old. All four were beds used in routine tritium handling. Initial stoichiometries were PdT/sub 0.3/ and UT/sub 0.7/ so that both operated at similar 1 to 130 kPa pressures. The He 3 from palladium ranged from the 0.002 mo1% lower level of sensitivity to 0.01% for PdT 2 at one year of age. The UT system showed 0.1% He 3 at 4 to 62 days and 0.1 to 10% at longer times, with the first cuts being high in He 3 . The palladium bed with 95 to 97% pure T 2 enriches the output to as high as 97 to 99%. 9 refs., 1 fig., 2 tabs

  20. (3He,α) reaction mechanism at high energy and neutron inner shell structure

    International Nuclear Information System (INIS)

    Wiele, J. van de.

    1980-01-01

    The ( 3 He,α) reaction on 12 C, 16 O, 28 Si, 58 Ni, 90 Zr, 118 Sn, 124 Sn and 208 Pb targets has been studied at Esub( 3 He) = 217 MeV (or 205 MeV) in order to investigate the reaction mechanism at high energy and large momentum transfer. The reaction yields large cross sections at very forward angles and strongly enhances the largest orbital momentum transfer. The angular distribution shapes are well reproduced in the frame-work of the Z-R- D.W.B.A. analysis if we use a unique empirical α-potential: Vsub(α)(Esub(α)) = Vsub( 3 He)(3/4 Esub(α)) + Vsub(n)(1/4 Esub(α)). The excitation energy spectra have been measured up to 100 MeV in the residual light and medium nuclei and up to about 16 MeV in heavy nuclei. In addition to the well-known low-lying levels, peaks or broad structures are observed for each nucleus at higher excitation energies. They are attributed to pick up from inner shells: 1s( 11 C and 15 O), 1p( 27 Si), 1d5/2 + 1p( 57 Ni), 1f7/2( 89 Zr) 1g9/2 117 Sn, 123 Sn and 1h11/2( 207 Pb). Selectivity and localization of direct and indirect pick up ( 3 He,α) reactions were studied. Finite range calculations show that this reaction is not very sensitive to the details of the range from function but only to D 0 coefficient and range R. A microscopic α-nucleus optical potential calculated with n-n dependent and independent density forces is able to reproduce both elastic scattering and pick up reaction angular distributions [fr

  1. Apparent CFC and 3H/ 3He age differences in water from Floridan Aquifer springs

    Science.gov (United States)

    Happell, James D.; Opsahl, Stephen; Top, Zafer; Chanton, Jeffrey P.

    2006-03-01

    The apparent CFC-11, -12 and -113 ages of Upper Floridan Aquifer water discharged from 31 springs located in Florida and Georgia ranged from 11 to 44 years when samples were collected in 2002 and 2003. Apparent 3H/ 3He ages in these springs ranged from 12 to 66 years. Some of the springs sampled did not yield valid CFC ages because one or more of the CFCs were contaminated by non-atmospheric sources. Of the 31 springs sampled, six were contaminated with all three CFCs and nine were contaminated with one or two CFCs. Of the remaining 16 springs, the CFC distributions of four could be modeled assuming a single source of water, and 11 were best modeled by assuming two sources of water, with one of the water sources >60 years old. The CFC and 3H/ 3He apparent ages and the simple mixing models applied to these ages suggest that past impacts to the water quality of water recharging the sampled springs may take anywhere from 0 to ˜60 years or more to appear in the discharging spring water. In 27 springs where both 3H/ 3He ages and CFC ages were available, five springs gave similar results between the two techniques, while in the other 22 cases the 3H/ 3He apparent ages were 8-40 years greater than the CFC ages. Large excesses of 4He were observed in many of the springs, consistent with a source of older water. This older water may also carry an additional and unaccounted for source of 3He, which may be responsible for the greater 3H/ 3He ages relative to the CFC ages. We believe that the large excess 3He and 4He values and apparent age differences are related to regional climate variations because our samples were obtained at the end of a 4-year drought.

  2. Experimental determination of differential cross sections of the reactions 4He(e,e'p), 4He(e,e'pp), and 4He(e,e'dp) with special regards to their possible indications for nucleon-nucleon correlations in the helium nucleus

    International Nuclear Information System (INIS)

    Eickhoff, W.

    2003-05-01

    Absolute, differential 4 He(e,e'p), (e,e'pp), and (e,e'dp) cross-sections in extended kinematical regions which are corresponding to the 'dip' between the quasielastic and the Δ-resonance peak in the 4 He(e,e') response-function have been measured at the high duty factor Electron Stretcher Accelerator ELSA of Bonn University. The scattered electrons were detected with a magnetic spectrometre, the hadrons with two sets of large-area plastic-scintillator telescopes. The measured cross-sections indicate important contributions from reactions on correlated nuclear pairs. In the 4 H(e,e'p) cross-sections the two-body break-up, 4 He(e,e'p)t, and the quasifree production of pions are visible as well. On the assumption of the Impulse-Approximation momentum-density distribution of the proton in 4 He have been derived from the measured cross-sections of the two-body and of the continuum break-up of the 4 He nucleus. (orig.)

  3. Production of 4He in D2-Loaded Palladium-Carbon Catalyst I

    International Nuclear Information System (INIS)

    Clarke, W. Brian

    2003-01-01

    A series of lead vials of internal volume 1.0 cm 3 were charged with ∼200 mg of carbon catalyst containing 0.5% Pd and 0.4% Pd. The vials were clamped to stainless steel manifolds on a vacuum line, then pumped out and filled with high-purity H 2 or D 2 at a pressure of 152 cm Hg and a temperature of 23 deg. C. Several vials contained ordinary activated carbon instead of palladium-carbon, and some vials contained only H 2 or D 2 . All the vials were stored in a sandbox heated to ∼ 200 deg. C for times up to 45 days before mass spectrometer measurements of 3 He and 4 He were made. No evidence was found for the high concentrations of 4 He claimed in similar experiments by several other researchers. The upper limit for the concentration excess of 4 He in D 2 in vials containing palladium-carbon is 11 ppt (parts per trillion) at the 95% confidence level. This limit for 4 He may be compared with previous claims in similar experiments of 100 ppm (parts per million) by Case and 11 ppm by George and McKubre et al

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

    Science.gov (United States)

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

    2010-04-01

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

  5. He2+ molecular ion and the He- atomic ion in strong magnetic fields

    Science.gov (United States)

    Vieyra, J. C. Lopez; Turbiner, A. V.

    2017-08-01

    We study the question of existence, i.e., stability with respect to dissociation of the spin-quartet permutation- and reflection-symmetric 4(-3) +g (Sz=-3 /2 ,M =-3 ) state of the (α α e e e ) Coulomb system: the He2 + molecular ion, placed in a magnetic field 0 ≤B ≤10 000 a.u. We assume that the α particles are infinitely massive (Born-Oppenheimer approximation of zero order) and adopt the parallel configuration, when the molecular axis and the magnetic field direction coincide, as the optimal configuration. The study of the stability is performed variationally with a physically adequate trial function. To achieve this goal, we explore several helium-containing compounds in strong magnetic fields, in particular; we study the spin-quartet ground state of the He- ion and the ground (spin-triplet) state of the helium atom, both for a magnetic field in 100 ≤B ≤10 000 a.u. The main result is that the He2 + molecular ion in the state 4(-3) +g is stable towards all possible decay modes for magnetic fields B ≳120 a .u . and with the magnetic field increase the ion becomes more tightly bound and compact with a cigar-type form of electronic cloud. At B =1000 a .u . , the dissociation energy of He2 + into He-+α is ˜702 eV and the dissociation energy for the decay channel to He +α +e is ˜729 eV , and both energies are in the energy window for one of the observed absorption features of the isolated neutron star 1E1207.4-5209.

  6. Hyperfine Structure Measurements of Antiprotonic $^3$He using Microwave Spectroscopy

    CERN Document Server

    Friedreich, Susanne

    The goal of this project was to measure the hyperfine structure of $\\overline{\\text{p}}^3$He$^+$ using the technique of laser-microwave-laser spectroscopy. Antiprotonic helium ($\\overline{\\text{p}}$He$^+$) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta of its constituents cause a hyperfine splitting ({HFS}) within the energy states of this new atom. The 3\\% of formed antiprotonic helium atoms which remain in a metastable, radiative decay-dominated state have a lifetime of about 1-3~$\\mu$s. This time window is used to do spectroscopic studies. The hyperfine structure of $\\overline{\\text{p}}^4$He$^+$ was already extensively investigated before. From these measurements the spin magnetic moment of the antiproton can be determined. A comparison of the result to the proton magnetic moment provides a test of {CPT} invariance. Due to its higher complexity the new exotic three-body system of $\\overline{\\text{p}}^3$He$^+$ is a cross-check...

  7. 3He-MRI in follow-up of lung transplant recipients

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  8. Bare astrophysical S(E)-factor for the 6Li(d, α)4He and 7Li(p, α)4He reactions at astrophysical energies

    International Nuclear Information System (INIS)

    Pizzone, R.G.; Spitaleri, C.; Lattuada, M.; Musumarra, A.; Pellegriti, M.G.; Romano, S.; Tumino, A.; Cherubini, S.; Figuera, P.; Miljanic, D.; Rolfs, C.; Typel, S.; Wolter, H.H.; Castellani, V.; Degl'Innocenti, S.; Imperio, A.

    2003-01-01

    The Trojan Horse Method has been applied to study the 7 Li(p, α) 4 He and 6 (Li(d, α) 4 He reactions through the 7 Li(d, αα)n and 6 Li( 6 Li, αα) 4 He three body processes, respectively. The electron screening potential deduced from these experiments is much larger than the adiabatic approximation prediction for both cases; the systematic discrepancy between data and theoretical predictions is thus confirmed. Astrophysical implications of these measurements are also discussed

  9. D and $^{3}He$ production in $\\sqrt{s}$ = 130 GeV Au + Au collisions

    CERN Document Server

    Adler, C; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J T; Barannikova, O Yu; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Bland, L C; Blyth, C O; Bonner, B E; Boucham, A; Brandin, A B; Cadman, R V; Caines, H; Calderón de la Barca-Sanchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chattopadhyay, S; Chen, M L; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Cormier, T M; Cramer, J G; Crawford, H J; De Mello, M; Deng, W S; Derevshchikov, A A; Didenko, L; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Finch, E; Fisyak, Yu; Flierl, D; Foley, Kenneth J; Fu, J; Gagunashvili, N D; Gans, J; Gaudichet, L; Germain, M; Geurts, F J M; Ghazikhanian, V; Grabski, J; Grachov, O A; Greiner, D E; Grigoriev, V; Guedon, M; Guschin, E; Hallman, T J; Hardtke, D; Harris, J W; Heffner, M; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Hümmler, H; Igo, G; Ishihara, A; Ivanshin, Yu I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kisiel, A; Klay, J L; Klein, S R; Klyachko, A A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Krämer, M; Kravtsov, P; Krüger, K; Kuhn, C; Kulikov, A V; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T J; Lednicky, R; Leontiev, V M; Le Vine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Ljubicic, T; Llope, W J; Lo Curto, G; Long, H; Longacre, R S; López-Noriega, M; Love, W A; Lynn, D; Majka, R; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnik, Yu M; Meshchanin, A P; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; Moltz, D; Moore, C F; Morozov, V; De Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, Grazyna Janina; Ogawa, A; Okorokov, V; Oldenburg, M; Oson, D; Paic, G; Pandey, S U; Panebratsev, Yu A; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevozchikov, V; Peryt, W; Petrov, V A; Platner, E D; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E V; Prindle, D J; Pruneau, C A; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D M; Reid, J G; Retière, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V L; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schröder, L S; Schüttauf, A; Schweda, K; Seger, J E; Seliverstov, D M; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimansky, S S; Shvetcov, V S; Skoro, G P; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, Reinhard; Stolpovsky, A; Strikhanov, M N; Stringfellow, B C; Struck, C; Suaide, A A P; Sugarbaker, E R; Suire, C; Sumbera, M; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Takahashi, J; Tang, A H; Thomas, J H; Tikhomirov, V; Trainor, T A; Trentalange, S; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T S; Underwood, D G; Van Buren, G; Van der Molen, A; Vanyashin, A V; Vasilevski, I M; Vasilev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T J; Westfall, G D; Whitten, C; Wieman, H H; Willson, R; Wissink, S W; Witt, R; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yokosawa, A; Yurevich, V I; Zanevsky, Yu V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N; 10.1103/PhysRevLett.87.262301

    2001-01-01

    The first measurements of light antinucleus production in Au + Au collisions at the Relativistic Heavy-Ion Collider are reported. The observed production rates for d and /sup 3/He are much larger than in lower energy nucleus-nucleus collisions. A coalescence model analysis of the yields indicates that there is little or no increase in the antinucleon freeze-out volume compared to collisions at CERN SPS energy. These analyses also indicate that the 3He freeze-out volume is smaller than the d freeze-out volume. (22 refs).

  10. Pre-scission 4He multiplicity in the 19F+197Au reaction

    International Nuclear Information System (INIS)

    Ikezoe, H.; Shikazono, N.; Nagame, Y.; Sugiyama, Y.; Tomita, Y.; Ideno, K.; Iwamoto, A.; Ohtsuki, T.

    1990-01-01

    Pre- and post-scission 4 He particle multiplicities for the 19 F+ 197 Au reaction in the excitation energy range of 43 to 90 MeV have been measured in coincidence with fission fragments. The coincident 4 He particles measured at backward angles are accounted for by evaporation from a compound nucleus and fission fragments. The most probable center-of-mass energy of the 4 He particles measured at backward angles is shifted towards lower energies by ∼2 MeV compared to a statistical model calculation performed by assuming 4 He emission from a spherical compound nucleus. The observed pre-scission 4 He multiplicity as a function of excitation energy is compared to a set of statistical-model calculations which also included the delayed onset of fission. The comparison shows that the observed energy dependence of the pre-scission 4 He multiplicity is reproduced by the calculation without taking into account the delayed onset of fission if the reduced emission barrier for 4 He is assumed in the calculation. The emission mechanism of the pre-scission 4 He is discussed

  11. Positive ion mobilities in normal liquid 3He at ultralow temperatures

    International Nuclear Information System (INIS)

    Alexander, P.W.

    1978-11-01

    The mobility has been measured of positive ions in liquid 3 he in the range 2.5 mK 3 sub(m)/sup(V) 5 sub(m)/sup(V). The effects of 500 p.p.m. 4 He in the 3 He were investigated. It was found that, at low temperatures, several stable ion species could be produced for 3 He pressures of 23 bar and above and, between 25 mK and 60 mK, time dependent conversion from one species of ion to another was observed at all pressures. The creation mechanism, mobility and stability of multiple positive ions were studied. Possible explanations of the phenomena are discussed. The measured drift field dependence of mobility is used to test the quasiparticle scattering model assumed for the liquid. (U.K.)

  12. Reconciling Conflicting Geologic and Thermochronologic Interpretations Via Multiple Apatite Thermochronometers (AHe, AFT, and 4He/3He): 6 Ma Incision of the Westernmost Grand Canyon

    Science.gov (United States)

    Winn, C.; Karlstrom, K. E.; Shuster, D. L.; Kelley, S.; Fox, M.

    2017-12-01

    The application of low-temperature apatite thermochronology to the incision history of the Grand Canyon has led to conflicting hypotheses of either a 70 Ma ("old") or conflict with these lines of evidence and indicate a much older ( 70 Ma) westernmost Grand Canyon. We reconcile this conflict by applying apatite (U-Th)/He ages (AHe), 4He/3He thermochronometry, and apatite fission track ages and lengths (AFT) to the same sample at a key location. Using HeFTy, t-T paths that predict these data show cooling from ˜100 °C to 40-60 °C at 70-50 Ma, long-term residence at 40-60 °C from 50-10 Ma, and cooling to surface temperatures after 10 Ma, indicating young incision. New AFT (5) and AHe (3) datasets are also presented here. When datasets are examined separately, AHe data show t-T paths that cool to surface temperatures during the Laramide, consistent with an "old" Canyon. When multiple methods are applied, t-T paths instead show young incision. This inconsistency demonstrates the age of the Grand Canyon controversy. Here we reconcile the difference in t-T paths by adjusting model parameters to account for uncertainty in the rate of radiation damage annealing in apatite during burial heating and the resulting variations in He retentivity. In this area, peak burial conditions during the Laramide were likely insufficient to fully anneal radiation damage that accumulated during prolonged near-surface residence prior to burial. We conclude that application of multiple thermochronometers from common rocks reconciles conflicting thermochronologic interpretations and these data are best explained by a "young" westernmost Grand Canyon.

  13. Measurement of differential cross section of D(3He,p)4He from 0.8 MeV to 3.6 MeV

    Science.gov (United States)

    Zhu, J. P.; Xiao, X.; Yan, S.; Gao, Y.; Xue, J. M.; Wang, Y. G.

    2017-12-01

    Precise knowledge of the nuclear reaction cross-section is crucial for nuclear reaction analysis methods and its applications. In order to apply nuclear reaction analysis methods to Plasma Facing Materials studies on 4.5 MV electrostatic accelerator at Peking University, differential cross-section for d(3He,p) α at several backward angles was measured with a relative error about ± 6.2 % , gives detailed information at the laboratory angle of 135° from 800 keV to 3600 keV, as well as a rough angular distribution from 130° to 160°.

  14. Reaction matrix calculation of 4He including Δ degrees of freedom

    International Nuclear Information System (INIS)

    Wakamatsu, Masashi.

    1979-06-01

    The effects of the Δ(3-3 resonance) components on the binding energy of 4 He are studied within the framework of the reaction matrix theory. In this approach, the Δ configurations in 4 He are introduced in terms of the NΔ transition potential by solving the reaction matrix equation and thus it goes beyond perturbation theory with the NΔ transition potential. Not only the two-body cluster energy but also the three-body cluster energy containing Δ configurations are calculated. (author)

  15. Multiple Tracer ({sup 4}He, {sup 14}C, {sup 39}Ar, {sup 3}H/{sup 3}He, {sup 85}Kr) Depth Profile in an Extensively Exploited Multilevel Aquifer System in the Venetian Plain, Italy

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, A.; Claude, C [Centre Europeen de Recherche et d' Enseignement des Geosciences de l' Environnement, Aix-en-Provence (France); Purtschert, R. [Climate and Environmental Physics, University of Bern (Switzerland); Sueltenfuss, J. [Institute of Environmental Physics, University of Bremen (Germany); Travi, Y. [UMR-EMMAH, Universite d' Avignon et des Pays de Vaucluse, Avignon (France)

    2013-07-15

    Individual dating tracers have their specific inherent properties, advantages and limitations. Apparent {sup 4}He accumulation ages are biased as a function of a prior unknown external helium influx; {sup 14}C (T{sub 1/2}: 5730 a) dating in groundwater requires suitable geochemical correction schemes and {sup 39}Ar (T{sub 1/2}: 269 a) may be affected by underground production. In a multiple tracer study in the Venetian Plain, Italy, using {sup 4}He, {sup 14}C. {sup 39}Ar {sup 3}H/{sup 3}He and {sup 85}Kr data, the groundwater residence times in a depth profile consisting of different separated aquifers between 50-350 m depth are estimated. Moreover, limitations and uncertainties of the applied tracer methods are identified, assessed and quantified. (author)

  16. Communication: Unraveling the 4He droplet-mediated soft-landing from ab initio-assisted and time-resolved density functional simulations: Au@4He300/TiO2(110)

    Science.gov (United States)

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

    2015-04-01

    An ab-initio-based methodological scheme for He-surface interactions and zero-temperature time-dependent density functional theory for superfluid 4He droplets motion are combined to follow the short-time collision dynamics of the Au@4He300 system with the TiO2(110) surface. This composite approach demonstrates the 4He 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 4He 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)].

  17. HE4 Transcription- and Splice Variants-Specific Expression in Endometrial Cancer and Correlation with Patient Survival

    Directory of Open Access Journals (Sweden)

    Shi-Wen Jiang

    2013-11-01

    Full Text Available We investigated the HE4 variant-specific expression patterns in various normal tissues as well as in normal and malignant endometrial tissues. The relationships between mRNA variants and age, body weight, or survival are analyzed. ICAT-labeled normal and endometrial cancer (EC tissues were analyzed with multidimensional liquid chromatography followed by tandem mass spectrometry. Levels of HE4 mRNA variants were measured by real-time PCR. Mean mRNA levels were compared among 16 normal endometrial samples, 14 grade 1 and 14 grade 3 endometrioid EC, 15 papillary serous EC, and 14 normal human tissue samples. The relationship between levels of HE4 variants and EC patient characteristics was analyzed with the use of Pearson correlation test. We found that, although all five HE4 mRNA variants are detectable in normal tissue samples, their expression is highly tissue-specific, with epididymis, trachea, breast and endometrium containing the highest levels. HE4-V0, -V1, and -V3 are the most abundant variants in both normal and malignant tissues. All variants are significantly increased in both endometrioid and papillary serous EC, with higher levels observed in grade 3 endometrioid EC. In the EC group, HE4-V1, -V3, and -V4 levels inversely correlate with EC patient survival, whereas HE4-V0 levels positively correlate with age. HE4 variants exhibit tissue-specific expression, suggesting that each variant may exert distinct functions in normal and malignant cells. HE4 levels appear to correlate with EC patient survival in a variant-specific manner. When using HE4 as a biomarker for EC management, the effects of age should be considered.

  18. Expectation values of the e+He(3Se) system

    International Nuclear Information System (INIS)

    Mitroy, J.

    2005-01-01

    Close to converged energies and expectation values for e + He( 3 S e ) are computed using a ground state wave function consisting of 1500 explicitly correlated Gaussians. The best estimate of the e + He( 3 S e ) energy was -2.250 595 08 hartree, which has a binding energy of 0.000 595 08 hartree against dissociation into Ps+He + . The 2γ annihilation rate for the spin doublet state was 5.713x10 9 s -1 . The estimated annihilation rate with the core He + electron was 2.506x10 6 s -1 . The derived enhancement factor for annihilation with the He + (1s) core was 2.29, just over 10% smaller than the enhancement factor derived from analyses of annihilation during e + -He + scattering. The diffuse nature of the wave function, with well separated He + and Ps subsystems, is demonstarted to be on the threshold of satisfying the formal criteria that define a quantum halo state

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

    Energy Technology Data Exchange (ETDEWEB)

    Arai, K.; Aoyama, S.; Suzuki, Y.; Descouvemont, P.; Baye, D. [Division of General Education, Nagaoka National College of Technology, 888 Nishikatakai, Nagaoka, Niigata, 940-8532 (Japan); Center for Academic Information Service, Niigata University, Niigata 950-2181 (Japan); Department of Physics, Niigata University, Niigata 950-2181, Japan and RIKEN Nishina Center, Wako 351-0198 (Japan); Physique Nucleaire Theorique et Physique Mathematique, C.P.229, Universite Libre de Bruxelles, B 1050 Brussels (Belgium); Physique Quantique, CP165/82, Universite Libre de Bruxelles, B-1050 Brussels (Belgium)

    2012-11-12

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

  20. Warm electrons on the liquid 4He surface

    International Nuclear Information System (INIS)

    Saitoh, Motohiko

    1977-01-01

    Detailed theoretical analysis of non-Ohmic transport of electrons on the liquid 4 He surface is given. The correct form of the electron-ripplon scattering as well as the electron- 4 He gas scattering is taken into account. A characteristic electric field at which electron mobility deviates from the Ohmic value is estimated as a function of temperature and the holding field on the basis of the electron effective temperature approximation. (auth.)

  1. Neutron Diffraction from the Second Layer of 4He on Graphite

    DEFF Research Database (Denmark)

    da Costa Carneiro, Kim; Passell, L.; Thomlinson, W.

    1981-01-01

    Neutron diffraction has been used to study the second atomic layer of **4He adsorbed on graphite. As the **4He-coverage exceeds the first layer, the second initially forms a fluid phase. But when there is enough **4He in the third layer to compress the second, this layer solidifies. The structure...

  2. Analytical W–He and H–He interatomic potentials for a W–H–He system

    International Nuclear Information System (INIS)

    Li Xiaochun; Shu Xiaolin; Liu Yinan; Yu Yi; Gao, F.; Lu Guanghong

    2012-01-01

    We have constructed W–He and H–He analytical bond-order potentials for a W–H–He system. In combination with the previously self-developed W–H potential [X.-C. Li, X. Shu, Y.-N. Liu, F. Gao, G.-H. Lu, J. Nucl. Mater. 408 (2011) 12] and the Hartree–Fock-dispersion pair potential (Aziz-potential) for He−He interactions, we demonstrate that such potentials behave well for reproducing various properties of the W–H–He system such as defect formation energies, structural properties, and diffusion barriers. Such potentials can be employed to model both the He behaviours and the H–He synergetic effects in the W–H–He system.

  3. [Effect of down-regulation of HE4 gene expression on biologic behavior of ovarian cancer cells].

    Science.gov (United States)

    Zhou, Lei; Xiao, Ran; Chen, Ying; Zhang, Jing; Lu, Ren-quan; Guo, Lin

    2013-10-01

    To investigate the effects of HE4 gene knockdown on the proliferation, adhesion and invasion of the ovarian cancer cells SKOV3. The knockdown of HE4 gene was performed by RNAi technology. The recombinant plasmids (pSUPER-HE4 shDNAs) were constructed and transfected into human ovarian cancer cells SKOV3. HE4 expression was then identified by real-time PCR and Western blot analysis. The invasion and adhesion ability of transduced cells were determined. In addition, cell proliferation and growth were analyzed by colonies formation assay. Knockdown of HE4 was achieved, and further confirmed by real-time PCR and Western blot. The proliferation of HE4-down-regulated cells was not affected, but the invasion ability of the transfected cells was reduced (P cells.

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

    International Nuclear Information System (INIS)

    Campbell, L.J.

    1983-01-01

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

  5. Fundamental parameters of He-weak and He-strong stars

    Science.gov (United States)

    Cidale, L. S.; Arias, M. L.; Torres, A. F.; Zorec, J.; Frémat, Y.; Cruzado, A.

    2007-06-01

    Context: He-weak and He-strong stars are chemically peculiar AB objects whose He lines are anomalously weak or strong for their MK spectral type. The determination of fundamental parameters for these stars is often more complex than for normal stars due to their abundance anomalies. Aims: We discuss the determination of fundamental parameters: effective temperature, surface gravity, and visual and bolometric absolute magnitudes of He-weak and He-strong stars. We compare our values with those derived independently from methods based on photometry and model fitting. Methods: We carried out low resolution spectroscopic observations in the wavelength range 3400-4700 Å of 20 He-weak and 8 He-strong stars to determine their fundamental parameters by means of the Divan-Chalonge-Barbier (BCD) spectrophotometric system. This system is based on the measurement of the continuum energy distribution around the Balmer discontinuity (BD). For a few He-weak stars we also estimate the effective temperatures and the angular diameters by integrating absolute fluxes observed over a wide spectral range. Non-LTE model calculations are carried out to study the influence of the He/H abundance ratio on the emergent radiation of He-strong stars and on their T_eff determination. Results: We find that the effective temperatures, surface gravities and bolometric absolute magnitudes of He-weak stars estimated with the BCD system and the integrated flux method are in good agreement between each other, and they also agree with previous determinations based on several different methods. The mean discrepancy between the visual absolute magnitudes derived using the hipparcos parallaxes and the BCD values is on average ±0.3 mag for He-weak stars, while it is ±0.5 mag for He-strong stars. For He-strong stars, we note that the BCD calibration, based on stars in the solar environment, leads to overestimated values of T_eff. By means of model atmosphere calculations with enhanced He/H abundance ratios

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

    Science.gov (United States)

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

    2013-05-01

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

  7. Modified VMD model with correct analytic properties for describing electromagnetic structure of He4 nucleus

    International Nuclear Information System (INIS)

    Dubnicka, S.; Lucan, L.

    1988-12-01

    A new phenomenological model for electromagnetic (e.m.) form factor (ff) of He 4 nucleus is presented, which is based on a modification of the well proved in e.m. interactions of hadrons vector-meson-dominance (VMD) model by means of an incorporation of correct He 4 ff analytic properties, nonzero vector-meson widths and the right power asymptotic behaviour predicted by the quark model. It reproduces the existing experimental information on He 4 e.m. ff in the space-like region quite well. Furthermore, couplings of all well established isoscalar vector mesons with J pc = 1 -- to He 4 nucleus are evaluated as a result of the analysis and the time-like region behaviour of He 4 e.m. ff is predicted. As a consequence of the latter the total cross section of e + e - → He 4 He-bar 4 process is calculated for the first time. (author). 17 refs, 3 figs

  8. Gersch-Rodriguez-Smith computation of deep inelastic electron scattering on 4He

    International Nuclear Information System (INIS)

    Viviani, M.; Kievsky, A.; Rinat, A.S.

    2003-01-01

    We compute cross sections for inclusive scattering of high-energy electrons on 4 He, based on the two lowest orders of the Gersch-Rodriguez-Smith series. The required one- and two-particle density matrices are obtained from nonrelativistic 4 He wave functions using realistic models for the nucleon-nucleon and three-nucleon interaction. The computed results for E=3.6 GeV agree well with the NE3 SLAC-Virginia data

  9. Optimizing moderation of He-3 neutron detectors for shielded fission sources

    Energy Technology Data Exchange (ETDEWEB)

    Rees, Lawrence B., E-mail: Lawrence_Rees@byu.edu [Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602 (United States); Czirr, J. Bart, E-mail: czirr@juno.com [Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602 (United States)

    2012-11-01

    The response of a {sup 3}He neutron detector is highly dependent on the amount of moderator incorporated into the detector system. If there is too little moderation, neutrons will not react with the {sup 3}He. If there is too much moderation, neutrons will not reach the {sup 3}He. In applications for portal or border monitors where {sup 3}He detectors are used to interdict illicit importation of plutonium, the fission source is always shielded to some extent. Since the energy distribution of neutrons emitted from the source depends on the amount and type of shielding present, the optimum placement of moderating material around {sup 3}He tubes is a function of shielding. In this paper, we use Monte Carlo techniques to model the response of {sup 3}He tubes placed in polyethylene boxes for moderation. To model the shielded fission neutron source, we use a point {sup 252}Cf source placed in the center of polyethylene spheres of varying radius. Detector efficiency as a function of box geometry and shielding is explored. We find that increasing the amount of moderator behind and to the sides of the detector generally improves the detector response, but that incremental benefits are minimal if the thickness of the polyethylene moderator is greater than about 5-7 cm. The thickness of the moderator in front of the {sup 3}He tubes, however, is very important. For bare sources, about 4-5 cm of moderator is optimum, but as the shielding increases, the optimum thickness of this moderator decreases to 0.5-1 cm. Similar conclusions can be applied to polyethylene boxes employing two {sup 3}He tubes. Two-tube boxes with front moderators of non-uniform thickness may be useful for detecting neutrons over a wide energy range.

  10. He I and He II Photoelectron Studies of Bis(cyclopentadienyl)vanadium(III) Complexes

    NARCIS (Netherlands)

    Green, Jennifer C.; Payne, Martin P.; Teuben, Jan H.

    He I and He II photoelectron spectra have been obtained for a series of bis(η5-cyclopentadienyl)vanadium(III) halides, alkyls, and aryls, V(η-C5H5)2X, where X = Cl, Br, I, Me, CH2SiMe3, CH2CMe3, C6F5, C6H5, o-C6H4Me, m-C6H4Me, and 2,6-C6H3Me2. Assignments are made principally on the basis of

  11. 'Two-color' reflection multilayers for He-I and He-II resonance lines for micro-UPS using Schwarzschild objective

    International Nuclear Information System (INIS)

    Ejima, Takeo; Kondo, Yuzi; Watanabe, Makoto

    2000-01-01

    'Two-color' multilayers reflecting both He-I (58.4 nm) and He-II (30.4 nm) resonance lines have been designed and fabricated for reflection coatings of Schwarzschild objectives of micro-UPS instruments. They are designed so that their reflectances for both He-I and He-II resonance lines are more than 20%. The 'two-color' multilayers are piled double layers coated with top single layers. Fabricated are multilayers of SiC(top layer)-Mg/SiC(double layers) and SiC(top layer)-Mg/Y 2 O 3 (double layers), and their reflectances for the He-I and the He-II are 23% and 17%, and 20% and 23%, respectively

  12. Plate Tectonic Cycling and Whole Mantle Convection Modulate Earth's 3He/22Ne Ratio

    Science.gov (United States)

    Dygert, N. J.; Jackson, C.; Hesse, M. A.; Tremblay, M. M.; Shuster, D. L.; Gu, J.

    2016-12-01

    3He and 22Ne are not produced in the mantle or fractionated by partial melting, and neither isotope is recycled back into the mantle by subduction of oceanic basalt or sediment. Thus, it is a surprise that large 3He/22Ne variations exist within the mantle and that the mantle has a net elevated 3He/22Ne ratio compared to volatile-rich planetary precursor materials. Depleted subcontinental lithospheric mantle and mid-ocean ridge basalt (MORB) mantle have distinctly higher 3He/22Ne compared to ocean island basalt (OIB) sources ( 4-12.5 vs. 2.5-4.5, respectively) [1,2]. The low 3He/22Ne of OIBs approaches chondritic ( 1) and solar nebula values ( 1.5). The high 3He/22Ne of the MORB mantle is not similar to solar sources or any known family of meteorites, requiring a mechanism for fractionating He from Ne in the mantle and suggesting isolation of distinct mantle reservoirs throughout geologic time. We model the formation of a MORB source with elevated and variable 3He/22Ne though diffusive exchange between dunite channel-hosted basaltic liquids and harzburgite wallrock beneath mid-ocean ridges. Over timescales relevant to mantle upwelling beneath spreading centers, He may diffuse tens to hundreds of meters into wallrock while Ne is relatively immobile, producing a regassed, depleted mantle lithosphere with elevated 3He/22Ne. Subduction of high 3He/22Ne mantle would generate a MORB source with high 3He/22Ne. Regassed, high 3He/22Ne mantle lithosphere has He concentrations 2-3 orders of magnitude lower than undegassed mantle. To preserve the large volumes of high 3He/22Ne mantle required by the MORB source, mixing between subducted and undegassed mantle reservoirs must have been limited throughout geologic time. Using the new 3He/22Ne constraints, we ran a model similar to [3] to quantify mantle mixing timescales, finding they are on the order of Gyr assuming physically reasonable seafloor spreading rates, and that Earth's convecting mantle has lost >99% of its primordial

  13. He stars and He-accreting CO white dwarfs

    International Nuclear Information System (INIS)

    Limongi, M.; Tornambe, A.

    1991-01-01

    He star models in the mass range 0.4-1.0 solar mass have been evolved until the red giant phase or, depending on their mass, until crystallization on the white-dwarf cooling sequence. Some of the degenerate structures obtained in these computations have been successively accreted at various He accretion rates in order to better define the fate of the accreting dwarf versus its mass and accretion rate for a fixed degeneracy level of the accreting dwarf. He stars have been further induced to transfer mass to a degenerate companion through Roche lobe overflow, in conditions of large gravitational wave radiation by the system. CO dwarfs in binary systems with He stars are found to experience a thermal behavior whose effects are such to locate the structure on the verge of obtaining a strong SN-like explosive event. 22 refs

  14. The new phases of liquid 3He

    International Nuclear Information System (INIS)

    Leggett, A.J.

    1976-01-01

    Comments are made on two new phases of liquid 3 He, referred to as 3 He-A and 3 He-B, discovered in the temperature region below 3 mk. It has been assumed that these new phases are anisotropic superfluids, and a general picture of them is presented, which has been successful in explaining at least qualitatively, many of the static, dynamic and transport properties of the new phases. Whilst the qualitative behaviour is in good agreement with theory there are, however, some quantitative discrepancies. In many cases these may be due to orientational and geometric effects not yet understood. One of the most fruitful areas for comparison of theory and experiment is the NMR behaviour and the dynamic nuclear magnetism. The anomalous behaviour observed arises because the nuclear dipole energy, although very small, can act coherently in the superfluid state. (U.K.)

  15. New solar axion search in CAST with $^4$He filling

    CERN Document Server

    Arik, M; Barth, K; Belov, A; Brauninger, 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; Galan, J; Garcia, J A; Gardikiotis, A.; Garza, J G; Gazis, E N; Geralis, T; Georgiopoulou, E; Giomataris, I; Gninenko, S; Marzoa, M Gomez; Hasinoff, M D; Hoffmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; K.Jakovcic; Karuza, M; Kavuk, M; Krcmar, M; Kuster, M; Lakic, B; Laurent, J M; Liolios, A; Ljubicic, A; Luzon, G; Neff, S; Niinikoski, T; Nordt, A; Ortega, I; Papaevangelou, T; Pivovaroff, M .J; Raffelt, G; Rodriguez, A; Rosu, M; Ruz, J; Savvidis, I; Shilon, I; Solanki, S K; Stewart, L; Tomas, A; Vafeiadis, T; Villar, J; Vogel, J K; Yildiz, S C; Zioutas, K

    2015-01-01

    The CERN Axion Solar Telescope (CAST) searches for $a\\to\\gamma$ 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 $m_\\gamma$ to the axion search mass $m_a$. After the vacuum phase (2003--2004), which is optimal for $m_a\\lesssim0.02$ eV, we used $^4$He in 2005--2007 to cover the mass range of 0.02--0.39 eV and $^3$He in 2009--2011 to scan from 0.39--1.17 eV. After improving the detectors and shielding, we returned to $^4$He in 2012 to investigate a narrow $m_a$ range around 0.2 eV ("candidate setting" of our earlier search) and 0.39--0.42 eV, the upper axion mass range reachable with $^4$He, to "cross the axion line" for the KSVZ model. We have improved the limit on the axion-photon coupling to $g_{a\\gamma}< 1.47\\times10^{-10} {\\rm GeV}^{-1}$ (95% C.L.), depending on the pressure settings. Since 2013, we have returned to vacuum and aim for a s...

  16. Lagrangian of superfluid 3He

    International Nuclear Information System (INIS)

    Theodorakis, S.

    1988-01-01

    This paper presents a phenomenological Lagrangian that fully describes the dynamics of any homogeneous phase of superfluid 3 He, unitary or not, omitting relaxation. This Lagrangian is built by using the concept of a local SO(3) x SO(3) x U(1) symmetry. The spin and angular momentum play the role of gauge fields. We derive the Leggett equations for spin and orbital dynamics from the equations of motion, for both the A and the B phase. This Lagrangian not only enables us to describe both the spin and orbital dynamics of superfluid 3 He in a unified fashion, but can also be used for finding the dynamics in any experimental situation. Furthermore, it can describe the dynamics of the magnitude, as well as of the orientation of the order parameter, and thus it can be used to describe the dynamics of the A-B phase transition

  17. Observation of flow dissipation in 3He-B

    International Nuclear Information System (INIS)

    Eisenstein, J.P.; Packard, R.E.

    1982-01-01

    Anomalous dissipation is observed in 3 He-B flowing in a U-tube device. The dissipation is of unknown origin and persists to the lowest measured velocity. The position of this result in the framework of other 3 He-B flow experiments is discussed

  18. HST/COS OBSERVATIONS OF THE QUASAR HE 2347-4342: PROBING THE EPOCH OF He II PATCHY REIONIZATION AT REDSHIFTS z = 2.4-2.9

    International Nuclear Information System (INIS)

    Shull, J. Michael; France, Kevin; Danforth, Charles W.; Smith, Britton; Tumlinson, Jason

    2010-01-01

    We report ultraviolet spectra of the high-redshift (z em ∼ 2.9) quasar, HE 2347 - 4342, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope. Spectra in the G130M (medium resolution, 1135-1440 A) and G140L (low resolution, 1030-2000 A) gratings exhibit patchy Gunn-Peterson absorption in the 303.78 A Lyα line of He II between z = 2.39-2.87 (G140L) and z = 2.74-2.90 (G130M). With COS, we obtain better spectral resolution, higher signal-to-noise ratio (S/N), and better determined backgrounds than previous studies, with sensitivity to abundance fractions x He I I ∼ 0.01 in filaments of the cosmic web. The He II optical depths from COS are higher than those with the Far Ultraviolet Spectroscopic Explorer and range from τ He I I ≤ 0.02 to τ He I I ≥ 5, with a slow recovery in mean optical depth to (τ He I I ) ≤ 2 at z abs ∼ z QSO and minimal 'proximity effect' of flux transmission at the He II edge. We propose a QSO systemic redshift z QSO = 2.904 ± 0.002, some Δz = 0.019 higher than that derived from O I λ1302 emission. Three long troughs (4-10 A or 25-60 Mpc comoving distance) of strong He II absorption between z = 2.75and2.90 are uncharacteristic of the intergalactic medium if He II reionized at z r ∼ 3. Contrary to recent indirect estimates (z r = 3.2 ± 0.2) from H I optical depths, the epoch of He II reionization may extend to z ∼< 2.7.

  19. Exploring advantages of 4He-PIXE analysis for layered objects in cultural heritage

    International Nuclear Information System (INIS)

    Roehrs, S.; Calligaro, T.; Mathis, F.; Ortega-Feliu, I.; Salomon, J.; Walter, P.

    2006-01-01

    In the field of cultural heritage 4 He particle beams are often used to perform RBS analysis. In most cases the simultaneously produced X-rays are not considered for PIXE analysis. This paper aims to explore the potentials of 4 He induced X-ray emission (α-PIXE) using 4, 5 and 6 MeV 4 He beams and to compare its performance with that of conventional PIXE with 3 MeV protons. The α-PIXE and α-RBS spectra were collected at the same time in a vacuum chamber. The X-ray yields produced by 6 MeV 4 He beam for K-lines were found to be superior to those of protons for atomic numbers below 25. An additional advantage of α-PIXE is the lower bremsstrahlung background which leads to an improved peak to noise ratio for certain elements

  20. Clinical importance of serum HE4 and MMP2 levels in endometrial cancer patients

    Directory of Open Access Journals (Sweden)

    Cymbaluk-Ploska A

    2017-06-01

    Full Text Available Aneta Cymbaluk-Płoska,1 Anita Chudecka-Głaz,1 Ewa Pius-Sadowska,2 Agnieszka Sompolska-Rzechuła,3 Bogusław Machaliński,2 Anna Surowiec,1 Janusz Menkiszak1 1Department of Gynecological Surgery and Gynecological Oncology of Adults and Adolescents, 2Department of General Pathology, Pomeranian Medical University, 3Department of Statistics, West Pomeranian University of Technology, Szczecin, Poland Introduction: Endometrial cancer is the one of the most common cancers of the genital organ. HE4 and MMP2 are both proteins whose serum levels increase in endometrial cancer.Aim: To explore the diagnostic potential of the serum levels of HE4 and MMP2 in patients with endometrial cancer and benign endometrial diseases. To assess the relationship between the serum levels of HE4 and MMP2 and the typical prognostic factors in patients with endometrial cancer.Materials and methods: Included in the study was a group of 112 patients presenting with bleeding abnormalities at the Pomeranian Medical University in years 2012–2016. Serum HE4 concentrations were measured using the Elecsys Electrochemiluminescence Immunoassay (ECLIA. MMP2 concentrations were quantified in the serum using multiplex immunoassays.Results: We observed statistically significant differences in mean serum levels of HE4 and MMP2 between the group of endometrial cancer patients and the group of patients with no changes in the endometrium (P=0.002/0.003. The diagnostic potential of HE4 and MMP2 in differentiation of high (International Federation of Gynecology and Obstetrics [FIGO] III and IV vs low (FIGO I and II clinical stage of tumor and prediction of cellular differentiation grade (G1 vs G3 on the basis of the analysis of the area under the curve is, respectively, 0.86 and 0.82 for HE4 and 0.82 and 0.74 for MMP2. The HE4 marker was significantly more specific than MMP2 in every study group and amounted to 93% vs 86% in all patients included in the analysis, 94% vs 84% in pre

  1. Low-energy 4He+ scattering from deuterium adsorbed on stepped Pd(331)

    International Nuclear Information System (INIS)

    Ellis, W.P.; Bastasz, R.

    1996-01-01

    We have taken angle-resolved data for the scattering of low-energy ( 4 He + from deuterium adsorbed on a stepped Pd(331) surface. The impact geometry was up the staircase, that is, the 4 He + beam was perpendicular to and directly incident onto the unshadowed Pd ledge atoms. A strong quasi-elastic scattering signal of 4 He + from D ( 4 He + /D) was observed at a forward scattering angle of θ = 25 degrees and an incidence angle of α = 76 degrees from the (331) normal. The results agree with shadow cone calculations of scattering first from Pd ledge atoms followed by a second event, 4 He + /D. The resultant adsorption geometry shows D to reside in the quasi- threefold ledge site on the surface directly above the bulk fcc octahedral void. These results are consistent with the previous 4 He + scattering study of the geometrically related Pd(110)- D(ads) system

  2. On the energy gain enhancement of DT+D3He fuel configuration in nuclear fusion reactor driven by heavy ion beams

    Directory of Open Access Journals (Sweden)

    S Khoshbinfar

    2016-09-01

    Full Text Available It is expected that advanced fuels be employed in the second generation of nuclear fusion reactors. Theoretical calculations show that in such a fuel, a high plasma temperature about 100 keV is a requisite for reaction rate improvement of nuclear fusion. However, creating such a temporal condition requires a more powerful driver than we have today. Here, introducing an optimal fuel configuration consisting of DT and D-3He layers, suitable for inertial fusion reactors and driven by heavy ion beams, the optimal energy gain conditions have been simulated and derived for 1.3 MJ system. It was found that, in this new fuel configuration, the ideal energy gain, is 22 percent more comparing with energy gain in corresponding single DT fuel layer. Moreover, the inner DT fuel layer contributed as an ignition trigger, while the outer D3He fuel acts as particle and radiation shielding as well as fuel layer.

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

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, C. J., E-mail: cforrest@lle.rochester.edu; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Romanofsky, M. H.; Sangster, T. C.; Shoup, M. J.; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States)

    2016-11-15

    Upgraded microchannel-plate–based photomultiplier tubes (MCP-PMT’s) with increased stability to signal-shape linearity have been implemented on the 13.4-m neutron time-of-flight (nTOF) detector at the Omega Laser Facility. This diagnostic uses oxygenated xylene doped with diphenyloxazole C{sub 15}H{sub 11}NO + p-bis-(o-methylstyryl)-benzene (PPO + bis-MSB) wavelength shifting dyes and is coupled through four viewing ports to fast-gating MCP-PMT’s, each with a different gain to allow one to measure the light output over a dynamic range of 1 × 10{sup 6}. With these enhancements, the 13.4-m nTOF can measure the D(t,n){sup 4}He and D(d,n){sup 3}He reaction yields and average ion temperatures in a single line of sight. Once calibrated for absolute neutron sensitivity, the nTOF detectors can be used to measure the neutron yield from 1 × 10{sup 9} to 1 × 10{sup 14} and the ion temperature with an accuracy approaching 5% for both the D(t,n){sup 4}He and D(d,n){sup 3}He reactions.

  4. Hard Two-Body Photodisintegration of He3

    Science.gov (United States)

    Pomerantz, I.; Ilieva, Y.; Gilman, R.; Higinbotham, D. W.; Piasetzky, E.; Strauch, S.; Adhikari, K. P.; Aghasyan, M.; Allada, K.; Amaryan, M. J.; Anefalos Pereira, S.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Beck, A.; Beck, S.; Bedlinskiy, I.; Berman, B. L.; Biselli, A. S.; Boeglin, W.; Bono, J.; Bookwalter, C.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Bubis, N.; Burkert, V.; Camsonne, A.; Canan, M.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Chirapatpimol, K.; Cisbani, E.; Cole, P. L.; Contalbrigo, M.; Crede, V.; Cusanno, F.; D'Angelo, A.; Daniel, A.; Dashyan, N.; de Jager, C. W.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dupre, R.; Dutta, C.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Fradi, A.; Garibaldi, F.; Geagla, O.; Gevorgyan, N.; Giovanetti, K. L.; Girod, F. X.; Glister, J.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Harrison, N.; Heddle, D.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jiang, X.; Jo, H. S.; Joo, K.; Katramatou, A. T.; Keller, D.; Khandaker, M.; Khetarpal, P.; Khrosinkova, E.; Kim, A.; Kim, W.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kubarovsky, V.; Kuleshov, S. V.; Kvaltine, N. D.; Lee, B.; LeRose, J. J.; Lewis, S.; Lindgren, R.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mao, Y.; Martinez, D.; Mayer, M.; McCullough, E.; McKinnon, B.; Meekins, D.; Meyer, C. A.; Michaels, R.; Mineeva, T.; Mirazita, M.; Moffit, B.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Nasseripour, R.; Nepali, C. S.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Petratos, G. G.; Phelps, E.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Procureur, S.; Protopopescu, D.; Puckett, A. J. R.; Qian, X.; Qiang, Y.; Ricco, G.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rodriguez, I.; Ron, G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saha, A.; Saini, M. S.; Sarty, A. J.; Sawatzky, B.; Saylor, N. A.; Schott, D.; Schulte, E.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Shneor, R.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S. S.; Stepanyan, S.; Stoler, P.; Subedi, R.; Sulkosky, V.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tkachenko, S.; Ungaro, M.; Vernarsky, B.; Vineyard, M. F.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Wang, Y.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Wojtsekhowski, B.; Wood, M. H.; Yan, X.; Yao, H.; Zachariou, N.; Zhan, X.; Zhang, J.; Zhao, Z. W.; Zheng, X.; Zonta, I.

    2013-06-01

    We have measured cross sections for the γHe3→pd reaction at photon energies of 0.4-1.4 GeV and a center-of-mass angle of 90°. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

  5. Hard two-body photodisintegration of 3He.

    Science.gov (United States)

    Pomerantz, I; Ilieva, Y; Gilman, R; Higinbotham, D W; Piasetzky, E; Strauch, S; Adhikari, K P; Aghasyan, M; Allada, K; Amaryan, M J; Anefalos Pereira, S; Anghinolfi, M; Baghdasaryan, H; Ball, J; Baltzell, N A; Battaglieri, M; Batourine, V; Beck, A; Beck, S; Bedlinskiy, I; Berman, B L; Biselli, A S; Boeglin, W; Bono, J; Bookwalter, C; Boiarinov, S; Briscoe, W J; Brooks, W K; Bubis, N; Burkert, V; Camsonne, A; Canan, M; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Chirapatpimol, K; Cisbani, E; Cole, P L; Contalbrigo, M; Crede, V; Cusanno, F; D'Angelo, A; Daniel, A; Dashyan, N; de Jager, C W; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Dutta, C; Egiyan, H; El Alaoui, A; El Fassi, L; Eugenio, P; Fedotov, G; Fegan, S; Fleming, J A; Fradi, A; Garibaldi, F; Geagla, O; Gevorgyan, N; Giovanetti, K L; Girod, F X; Glister, J; Goetz, J T; Gohn, W; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Harrison, N; Heddle, D; Hicks, K; Ho, D; Holtrop, M; Hyde, C E; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jiang, X; Jo, H S; Joo, K; Katramatou, A T; Keller, D; Khandaker, M; Khetarpal, P; Khrosinkova, E; Kim, A; Kim, W; Klein, F J; Koirala, S; Kubarovsky, A; Kubarovsky, V; Kuleshov, S V; Kvaltine, N D; Lee, B; LeRose, J J; Lewis, S; Lindgren, R; Livingston, K; Lu, H Y; MacGregor, I J D; Mao, Y; Martinez, D; Mayer, M; McCullough, E; McKinnon, B; Meekins, D; Meyer, C A; Michaels, R; Mineeva, T; Mirazita, M; Moffit, B; Mokeev, V; Montgomery, R A; Moutarde, H; Munevar, E; Munoz Camacho, C; Nadel-Turonski, P; Nasseripour, R; Nepali, C S; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Pappalardo, L L; Paremuzyan, R; Park, K; Park, S; Petratos, G G; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Procureur, S; Protopopescu, D; Puckett, A J R; Qian, X; Qiang, Y; Ricco, G; Rimal, D; Ripani, M; Ritchie, B G; Rodriguez, I; Ron, G; Rosner, G; Rossi, P; Sabatié, F; Saha, A; Saini, M S; Sarty, A J; Sawatzky, B; Saylor, N A; Schott, D; Schulte, E; Schumacher, R A; Seder, E; Seraydaryan, H; Shneor, R; Smith, G D; Sokhan, D; Sparveris, N; Stepanyan, S S; Stepanyan, S; Stoler, P; Subedi, R; Sulkosky, V; Taiuti, M; Tang, W; Taylor, C E; Tkachenko, S; Ungaro, M; Vernarsky, B; Vineyard, M F; Voskanyan, H; Voutier, E; Walford, N K; Wang, Y; Watts, D P; Weinstein, L B; Weygand, D P; Wojtsekhowski, B; Wood, M H; Yan, X; Yao, H; Zachariou, N; Zhan, X; Zhang, J; Zhao, Z W; Zheng, X; Zonta, I

    2013-06-14

    We have measured cross sections for the γ(3)He → pd reaction at photon energies of 0.4-1.4 GeV and a center-of-mass angle of 90°. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

  6. Quasimolecular autoionization in the collisions He+ - He, H2

    International Nuclear Information System (INIS)

    Ogurtsov, G.N.; Krupyshev, A.G.; Gordeev, Yu.S.

    1993-01-01

    Data on the autoionization transition level width dependence Γ(R) for He + - He, He + - H 2 pairs are obtained. Data on the probability of autoionization transition in a three-atom quasimolecule are obtained for the first time. It is shown that Γ(R) values for He + - He 2 quasimolecule exceed notably the similar values for isoelectron He + - He quasimolecule and may reach ∼ 1 eV. 6 refs., 2 figs

  7. Final results for the excitation function and angular distributions of the 3H(d,n)4He reaction

    International Nuclear Information System (INIS)

    Tang Hongqing; Zhou Zuying; Qi Bujia; Zhou Chenwei; Du Yanfeng; Xia Haihong; Chen Zemin; Chen Zhenpeng; Chen Yingtang

    1998-01-01

    The final relative excitation function of the 3 H(d,n) 4 He rection at 0 degree is shown out. For comparison, a curve calculated from Drosg's HI-13 tandem is in progressplotted. The angular distributions of the 3 H(d,n) 4 He reaction at E d =13.36, 16.50 and 19.50 Mev in the center-of-mass system are shown out. A comparison of the legendre polynomial coefficients obtained from the present angular distribution data with Drosg's evaluation are reported

  8. Production of d, t, 3He, anti d, anti t and anti 3He by 200 GeV protons

    International Nuclear Information System (INIS)

    Bozzoli, W.; Giacomelli, G.; Rimondi, F.; Zylberajch, S.; Lesquoy, E.; Meunier, R.; Moscoso, L.; Muller, A.; Bussiere, A.

    1978-01-01

    Data are presented on the yields of d, t, 3 He, anti d, anti t, and anti 3 He with laboratory momenta between 12 and 37 GeV/c produced by 200 GeV protons on beryllium and aluminium. The production yield of nuclei depends significantly on the target nucleus, while the anti d production is independent of target material. The mass dependence of the production cross section is exponential for both nuclei and antinuclei

  9. Development of a proof of concept low temperature 4He Superfluid Magnetic Pump

    Science.gov (United States)

    Jahromi, Amir E.; Miller, Franklin K.

    2017-03-01

    We describe the development and experimental results of a proof of concept Superfluid Magnetic Pump in this work. This novel low temperature, no moving part pump can replace the existing bellows-piston driven 4He or 3He-4He mixture compressor/circulators used in various sub Kelvin refrigeration systems such as dilution, Superfluid pulse tube, Stirling, or active magnetic regenerative refrigerators. Due to the superior thermal transport properties of sub-Lambda 4He this pump can also be used as a simple circulator to distribute cooling over large surface areas. Our pump was experimentally shown to produce a maximum flow rate of 440 mg/s (averaged over cycle), 665 mg/s (peak) and produced a maximum pressure difference of 2323 Pa using only the more common isotope of helium, 4He. This pump worked in an ;ideal; thermodynamic state: The experimental results matched with the theoretical values predicted by a computer model. Pump curves were developed to map the performance of this pump. This successful demonstration will enable this novel pump to be implemented in suitable sub Kelvin refrigeration systems.

  10. Development of 3He-BOCA power ramping facility, 1

    International Nuclear Information System (INIS)

    Nakata, Hirokatsu; Ishii, Tadahiko; Itoh, Haruhiko; Abe, Hiroshi; Nakazaki, Chozaburo

    1979-11-01

    Development of a He-3 power controlled boiling water capsule, 3 He-BOCS, for LWR fuels power ramping test in JMTR has been carried out since 1978 on a five-year program; in the reactor, irradiation tests of various fuels and structual materials have been made since 1969. Using stagnant-pressurized water as a thermal medium, the capsule provides pressure and temperature conditions similar to those in LWRs. Heat generation of a fuel pin can be controlled by a He-3 gas screen surrounding the capsule. The facility is capable of testing numbers of both fresh and irradiated fuel pins under LWR operating conditions for power ramping and cycling. After explaining the operating priciples of 3 He-BOCA and the development program, the following are described: the results of preliminary out-of-pile test on heat conductive characteristics of the capsule and a conceptual design of the 3 He-BOCA for power ramping of a short fuel pin from 250 W/cm to 500 W/cm under BWR conditions. (author)

  11. Development of polarized {sup 3}He filter for polarized neutron experiment

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, K.; Sato, H.; Yoshimi, A.; Asahi, K. [Tokyo Inst. of Tech. (Japan). Faculty of Science; Masuda, Y.; Muto, S.; Ishimoto, S.; Morimoto, K.

    1996-08-01

    A high-pressure polarized {sup 3}He gas cell, pumped with two diode lasers, has been developed at KEK for use as a polarizer and a spin analyzer for low energy neutrons. The polarization attained of {sup 3}He was determined through the measurement of the transmission of the unpolarized neutrons through the {sup 3}He cell. So far we obtained P{sub He}=18% at 10 atm and P{sub He}=12% at 20 atm. (author)

  12. Quantum beats study of the 4He+ beam-carbon foil interaction

    International Nuclear Information System (INIS)

    Denis, A.; Desesquelles, J.

    1979-01-01

    Excitation cross-sections are deduced from the analysis of quantum beats in an electric field for an 4 He + (n=4) ion beam scattering through a thin carbon foil. The population distribution obtained at 1 MeV for 4S, 4P, 4D and 4F levels is in good agreement with a second-order Born approximation calculation of the electronic capture He ++ +C→He + (n=4) + C + . The alignment is found to be negative for P, D and F levels. The coherences Δl=+-1 have been measured, for amplitudes and phases [fr

  13. Even-parity quartet autodetaching states of He-

    International Nuclear Information System (INIS)

    Hazi, A.U.

    1981-01-01

    The total photodetachment cross section of the metastable, (1s2s2p) 4 P 0 state of He - has been recently measured at several wavelengths between 10 μ and 308 nm. As part of these calculations, the even parity, quartet, autodetaching states of He - which are optically connected to the metastable 4 P 0 state and which are associated with the n = 2 and n = 3 states of He were studied. In both the photodetachment and electron scattering calculations, extensive configuration interaction (CI) wavefunctions were used to describe the He target states, the He - resonance states and the photodetachment continua. The Stieltjes moment-theory technique was used to extract the partial photodetachment cross sections from the discrete representations of the electron scattering continua. The use of the Stieltjes technique allowed the inclusion of both channel-channel coupling and fully correlated He 3 S and 3 P 0 wavefunctions in the calculations. Results are presented and discussed

  14. Thermal release of {sup 3}He from tritium aged LaNi{sub 4.25}Al{sub 0.75} hydride

    Energy Technology Data Exchange (ETDEWEB)

    Staack, G.C.; Crowder, M.L.; Klein, J.E. [Savannah River National Laboratory, Aiken, SC (United States)

    2015-03-15

    The Savannah River Site Tritium Facilities (SRS-TF) utilizes LANA.75 (LaNi{sub 4.25}Al{sub 0.75})in the tritium process to store hydrogen isotopes. The vast majority of {sup 3}He born from the radioactive decay of tritium stored in LANA.75 is trapped in the hydride metal matrix. The SRS-TF has multiple LANA.75 tritium storage beds that have been retired from service with significant quantities of He-3 trapped in the metal. To support He-3 recovery, the Savannah River National Laboratory (SRNL) conducted thermogravimetric analysis coupled with mass spectrometry (TGA-MS) on a tritium aged LANA.75 sample. TGA-MS testing was performed in an argon environment. Prior to testing, the sample was isotopically exchanged with deuterium to reduce residual tritium and passivated with air to alleviate pyrophoric concerns associated with handling the material outside of an inert glovebox. Analyses indicated that gas release from this sample was bimodal, with peaks near 220 and 490 C. degrees. The first peak consisted of both {sup 3}He and residual hydrogen isotopes, the second was primarily {sup 3}He. The bulk of the gas was released by 600 Celsius degrees. (author)

  15. Observation of mass flux through hcp 4He off the melting curve

    International Nuclear Information System (INIS)

    Ray, M W; Hallock, R B

    2009-01-01

    Solid hcp 4 He has been created off the melting curve using two growth techniques. In an effort to observe the flow of 4 He through the solid, rather than squeezing the solid directly, the experimental apparatus allows injection of 4 He atoms from superfluid in porous Vycor directly into the solid. We will describe the apparatus and our observations. Evidence for the transport of mass through a sample cell filled with hcp solid 4 He off the melting curve is found. The temperature and pressure dependence of this behavior will be presented.

  16. 3He and chlorofluorocarbons (CFC) in the Southern Ocean

    International Nuclear Information System (INIS)

    Jean-Baptiste, P.; Jamous, D.; Mantisi, F.; Memery, L.; Universite Paris 6

    1991-01-01

    The distribution of 3 He across the Southern Ocean is depicted on the basis of a meridional section between Antarctica and South Africa measured during the INDIGO-3 survey (1988). A core of δ 3 He values above 10% is observed south of the Polar Front, associated with very low CFC concentrations. This 3 He enriched layer is documented from the GEOSECS and INDIGO 3 He data in the Southern Ocean. It is found at a density level around θ σ =27.8 in all the waters close to Antarctica (i.e. south of 50 degS). Its zonal distribution suggests that it is likely that it originates from the central/eastern Pacific. Hence, it provides an indication of the deep Pacific waters in the Antarctic Circumpolar Current, which are not easily detectable from the standard hydrographic parameters. (author). 19 refs.; 8 figs

  17. Measurement of excitation functions and isomeric ratios of the 197Au(3He,xn)200- sup(x)Tl reactions, where x=2,3 and 4

    International Nuclear Information System (INIS)

    Vinagre Filho, U.M.

    1983-01-01

    The excitation functions and isomer ratios of the 197 Au( 3 He,xn) 200- sup(x)Tl reactions, with x = 2, 3 and 4, were measured at bombarding energies in the range from 15 to 36 MeV. The measured values were compared to those obtained with the use of the statistical an hybrid modeles, calculated by the ALICE code. Best fit was achieved using the simple statistical model. The results were also compared to those found in literature for the ( 3 He,xn) and ( 4 He,xn) reactions in gold. (Author) [pt

  18. Experimental Research of the Radiative Capture of Thermal Neutrons in $^{3}$He

    CERN Document Server

    Bystritsky, V M; Enik, T L; Filipowicz, M; Gerasimov, V V; Grebenyuk, V M; Kobzev, A P; Kublikov, R V; Nesvizhevsky, V V; Parzhitskii, S S; Pavlov, V N; Popov, N P; Salamatin, A V; Shvetsov, V N; Slepnev, V M; Strelkov, A V; Wozniak, J; Zamyatin, N I

    2006-01-01

    A project of an experiment on measurement of the cross sections of radiative thermal neutron capture by $^{3}$He nuclei with production of one and two $\\gamma $-quanta ($n_{\\rm th}+^{3}$He $\\to \\alpha + \\gamma $(2$\\gamma $)) is presented. The interest in studying the processes is dictated by the following factors: a possibility of obtaining information on parameters of the nucleon $N$-$N$ potential and structure of exchange meson currents; a possibility of verifying the model of the mechanism for nucleon capture by the nucleus $^{3}$He in the low-energy region; necessity to solve some questions existing in astrophysics. The experiment is planned to be carried out on the PF1B beam of ILL reactor (Grenoble). The target is a hollow cylinder of pure aluminium ($\\varnothing$140$\\times $80~mm) filled with $^{3}$He and $^{4}$He (background experiment) at the pressure 2~atm. Registration of the $\\gamma $-quanta is carried out by four BGO crystal ($\\varnothing$100$\\times $70~mm) detectors. According to the calculation...

  19. Analysis of the reaction 3He + p → p + p + d at 2,5 GeV/c 3He nucleus momentum

    International Nuclear Information System (INIS)

    Blinov, A.V.; Chuvilo, I.V.; Drobot, V.V.

    1984-01-01

    The experimental data on the reaction 3 He+p → p+p+d obtained by the exposition of an 80 cm liquid hydrogen bubble chamber to the 3 He nucleus beam at 2.5 GeV/c momentum are considered. The angular, momentum and invariant mass distributions, which have been measured, are compared with theoretical calculations performed using the pole model. On the whole a satisfactory agreement between theoretical and experimental data is found in the kinematical region, where pd- rescattering effects are negligible. It is concluded, that 3 He nuclear wave function calculated by means of nonrelativistic potential models falls too sharply with the spectator momenta as compared with the data

  20. Superheavy hydrogen 5H. Spectroscopy of 7He

    International Nuclear Information System (INIS)

    Korsheninnikov, A.A.; Golovkov, M.S.; Ozawa, A.

    2002-01-01

    Recent experiments with radioactive beams for spectroscopy of 5 H and 7 He are presented. It is studied the reaction p( 6 He, pp) 5 H. Preliminary results show a peak which is a good candidate for the resonance 5 H. In study of the reaction p( 8 He, d) 7 He, it is observed an excited state of 7 He which decays into 4 He + 3n [ru

  1. Interactions of 29 MeV. He{sup 3} particles with light nuclei; Interacciones de un haz de particulas 3{sup H}e de 29 MeV sobre nucleos ligeros

    Energy Technology Data Exchange (ETDEWEB)

    Rubia de la Pacheco, J.

    1964-07-01

    The interactions of 29 MeV He{sup 3} particles with 32{sup S}, 19{sup F} and 12{sup C}, irradiated in the Nuffield cyclotron (Birmingham University) have been studied using the nuclear emulsion technique. The first excitation levels of 12{sup C} and 32{sup S} have been obtained and the pick-up reaction 12{sup C}(3{sup H}e, 4{sup H}e) 11{sup C} has been studied and used to calculate its Q-values and the first levels of 1{sup C}. (Author) 24 refs.

  2. I. A model for the magnetic equation of state of liquid 3He. II. An induced interaction model for a two-component Fermi liquid

    International Nuclear Information System (INIS)

    Sanchez-Castro, C.R.

    1988-01-01

    This dissertation is divided in six chapters. Chapter 1 is an introduction to the rest of the dissertation. In it, the author presents the different models for the magnetic equation state of liquid 3 He, a derivation of the induced interaction equations for a one component Fermi liquid, and discuss the basic hamiltonian describing the heavy fermion compounds. In Chapter 2 and Chapter 3, he presents a complete discussion of the thermodynamics and Landau theory of a spin polarized Fermi liquid. A phenomenological model is then developed to predict the polarization dependence of the longitudinal Landau parameters in liquid 3 He. This model predicts a new magnetic equation of state and the possibility of liquid 3 He being 'nearly metamagnetic' at high pressures. Chapter 4 contains a microscopic calculation of the magnetic field dependence of the Landau parameters in a strongly correlated Fermi system using the induced interaction model. The system he studied consists of a single component Fermi liquid with parabolic energy bands, and a large on-site repulsive interaction. In Chapter 5, he presents a complete discussion of the Landau theory of a two component Fermi liquid. Then, he generalizes the induced interaction equations to calculate Landau parameters and scattering amplitudes for an arbitrary, spin polarized, two component Fermi liquid. The resulting equations are used to study a model for the heavy fermion Fermi liquid state: a two band electronic system with an antiferromagnetic interaction between the two bands. Chapter 6 contains the concluding remarks of the dissertation

  3. Energy dependence phase shift analysis of PI4He elastic scattering and the possibility of the (PI4He) excited states existence

    International Nuclear Information System (INIS)

    Nichitiu, F.; Falomkin, I.V.; Sapozhnikov, M.G.; Shcherbakov, Yu.A.; Piragino, G.

    1981-06-01

    In the 24 MeV-260 MeV kinetic energy interval, the energy dependent phase shift analysis of π 4 He elastic scattering is done. The eneray dependence is given by the rational fraction approximants of the partial S matrix. The search for the stable S matrix zero-pole pairs in the k and √s complex plane give some proofs for the existence of the (π 4 He) excited states in the S, P and probably D partial waves. (authors)

  4. 5He, 7He, and 8Li (E*=2.26 MeV) intermediate ternary particles in the spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    Kopatch, Yu.N.; Mutterer, M.; Schwalm, D.; Thirolf, P.; Goennenwein, F.

    2002-01-01

    The neutron-unstable odd-N isotopes 5 He, 7 He, and 8 Li (in its excited state of E*=2.26 MeV) were measured to show up as short-lived (τ≅10 -21 -10 -20 s) intermediate light charged particles (LCPs) in ternary fission of 252 Cf. For the study a high-efficiency angular correlation measurement between neutrons, LCPs, and main fission fragments has been performed. The evidence for the ternary 5 He and 7 He particles (lifetimes: 1x10 -21 s, and 4x10 -21 s, respectively) was disclosed from the measured angular distributions of their decay neutrons focused by the emission in flight towards the direction of motion of 4 He and 6 He ternary particles. Similarly, neutrons observed to be peaked around Li-particle motion could be attributed to the decay of the second excited state at E*=2.26 MeV (lifetime: 2x10 -20 s) of 8 Li. The fractional yields of the intermediate 5 He and 7 He ternary fission modes relative to the 'true' ternary 4 He and 6 He modes, respectively, were determined to be 0.21(5) for both cases. The mean energy of the 4 He residues resulting from the 5 He decay was determined to be 12.4(3) MeV, compared to 15.7(2) MeV for all ternary α particles registered, and to 16.4(3) MeV for the true ternary α particles. The mean energy of the 6 He residues from the 7 He decay is 11.0(15) MeV, compared to 12.3(5) MeV for all ternary 6 He particles. The population of 8 Li* was deduced to be 0.06(2) relative to Li ternary fission, and 0.33(20) relative to the yield of particle stable 8 Li. The perspective of using the observed intermediate LCPs for probing the ternary scission configuration in 252 Cf fission with the aid of trajectory calculations is briefly discussed

  5. 5He, 7He and 8Li (E=2.26 MeV) intermediate ternary particles in the spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    Kopatch, Yu. N.; Goennenwein, F.

    2002-02-01

    The neutron-unstable odd-N isotopes 5 He, 7 He and 8 Li (in its excited state of E * = 2.26 MeV) were measured to show up as short-lived intermediate light-charged-particles (LCP) in ternary fission of 252 Cf. For the study a high-efficiency angular correlation measurement between neutrons, LCPs and main fission fragments has been performed. The evidence for the ternary 5 He and 7 He particles (lifetimes: 1 x 10 -21 s, and 4 x 10 -21 s, respectively) was disclosed from the measured angular distributions of their decay neutrons focused by the emission in flight towards the direction of motion of 4 He and 6 He ternary particles. Similarly, neutrons observed to be peaked around Li-particle motion could be attributed to the decay of the second excited state at E * = 2.26 MeV (lifetime: 2 x 10 -20 s) of 8 Li. The fractional yields of the intermediate 5 He and 7 He ternary fission modes relative to the ''true'' ternary 4 He and 6 He modes, respectively, were determined to be 0.21(5) for both cases. The mean energy of the 4 He residues resulting from the 5 He decay was determined to be 12.4(3) MeV, compared to 15.7(2) MeV for all ternary α-particles registered, and to 16.4(3) MeV for the true ternary α-particles. The mean energy of the 6 He residues from the 7 He decay is 11.0(15) MeV, compared to 12.3(5) MeV for all ternary 6 He particles. The population of 8 Li * was deduced to be 0.06(2) relative to Li ternary fission, and 0.33(20) relative to the yield of particle stable 8 Li. The perspective of using the observed intermediate LCPs for probing the ternary scission configuration in 252 Cf fission with the aid of trajectory calculations is briefly discussed. (orig.)

  6. Transport of NaYF4:Er3+, Yb3+ up-converting nanoparticles into HeLa cells

    International Nuclear Information System (INIS)

    Sikora, Bożena; Fronc, Krzysztof; Kamińska, Izabela; Wojciechowski, Tomasz; Sobczak, Kamil; Minikayev, Roman; Paszkowicz, Wojciech; Elbaum, Danek; Koper, Kamil; Stępień, Piotr; Szewczyk, Sebastian; Paterczyk, Bohdan

    2013-01-01

    An effective, simple and practically useful method to incorporate fluorescent nanoparticles inside live biological cells was developed. The internalization time and concentration dependence of a frequently used liposomal transfection factor (Lipofectamine 2000) was studied. A user friendly, one-step technique to obtain water and organic solvent soluble Er 3+ and Yb 3+ doped NaYF 4 nanoparticles coated with polyvinylpyrrolidone was obtained. Structural analysis of the nanoparticles confirmed the formation of nanocrystals of the desired sizes and spectral properties. The internalization of NaYF 4 nanoparticles in HeLa cervical cancer cells was determined at different nanoparticle concentrations and for incubation periods from 3 to 24 h. The images revealed a redistribution of nanoparticles inside the cell, which increases with incubation time and concentration levels, and depends on the presence of the transfection factor. The study identifies, for the first time, factors responsible for an effective endocytosis of the up-converting nanoparticles to HeLa cells. Thus, the method could be applied to investigate a wide range of future ‘smart’ theranostic agents. Nanoparticles incorporated into the liposomes appear to be very promising fluorescent probes for imaging real-time cellular dynamics. (paper)

  7. Transport of NaYF4:Er3+, Yb3+ up-converting nanoparticles into HeLa cells

    Science.gov (United States)

    Sikora, Bożena; Fronc, Krzysztof; Kamińska, Izabela; Koper, Kamil; Szewczyk, Sebastian; Paterczyk, Bohdan; Wojciechowski, Tomasz; Sobczak, Kamil; Minikayev, Roman; Paszkowicz, Wojciech; Stępień, Piotr; Elbaum, Danek

    2013-06-01

    An effective, simple and practically useful method to incorporate fluorescent nanoparticles inside live biological cells was developed. The internalization time and concentration dependence of a frequently used liposomal transfection factor (Lipofectamine 2000) was studied. A user friendly, one-step technique to obtain water and organic solvent soluble Er3+ and Yb3+ doped NaYF4 nanoparticles coated with polyvinylpyrrolidone was obtained. Structural analysis of the nanoparticles confirmed the formation of nanocrystals of the desired sizes and spectral properties. The internalization of NaYF4 nanoparticles in HeLa cervical cancer cells was determined at different nanoparticle concentrations and for incubation periods from 3 to 24 h. The images revealed a redistribution of nanoparticles inside the cell, which increases with incubation time and concentration levels, and depends on the presence of the transfection factor. The study identifies, for the first time, factors responsible for an effective endocytosis of the up-converting nanoparticles to HeLa cells. Thus, the method could be applied to investigate a wide range of future ‘smart’ theranostic agents. Nanoparticles incorporated into the liposomes appear to be very promising fluorescent probes for imaging real-time cellular dynamics.

  8. Physics analysis of the Apollo D-3He tokamak reactor

    International Nuclear Information System (INIS)

    Santarius, J.F.; Emmert, G.A.

    1990-01-01

    Recent developments in the analysis and conceptual design of Apollo, a D- 3 He Tokamak Reactor are presented. Encouraging experimental results on TEXT motivated a key change in the Apollo concept utilization of an ergodic magnetic limiter for impurity control instead of a divertor. Parameters for the updated Apollo design and an analysis of the ergoidc magnetic limiter are given. The Apollo reference case uses direct conversion of synchrotron radiation to electricity by rectifying antennas (rectennas) for its power conversion system. Previous analyses of this concept are expanded, including further details of the rectennas and of the loss of synchrotron power to the waveguides and walls. Although Apollo will burn D- 3 He fuel, a significant amount of unburned tritium will be generated by D4D reactions. The possibility of operating a short, dedicated, T+ 3 He burn phase to eliminate this tritium will be examined

  9. High-pressure {sup 4}He drift tubes for fissile material detection

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhehui, E-mail: zwang@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Morris, Christopher L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Gray, F.E. [Regis University, Denver, CO 80221 (United States); Bacon, J.D.; Brockwell, M.I.; Chang, D.Y.; Chung, K.; Dai, W.G.; Greene, S.J.; Hogan, G.E.; Lisowski, P.W.; Makela, M.F.; Mariam, F.G.; McGaughey, P.L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mendenhall, M. [California Institute of Technology, Pasadena, CA 91125 (United States); Milner, E.C.; Miyadera, H.; Murray, M.M.; Perry, J.O.; Roybal, J.D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); and others

    2013-03-01

    A detector efficiency model based on energy extraction from neutrons is described and used to compare {sup 4}He detectors with liquid scintillators (EJ301/NE-213). Detector efficiency can be divided into three regimes: single neutron scattering, multiple neutron scattering, and a transition regime in-between. For an average fission neutron of 2 MeV, the amount of {sup 4}He needed would be about 1/4 of the amount of the mass of EJ301/NE-213 in the single-scattering regime. For about 50% neutron energy extraction (1 MeV out of 2 MeV), the two types of detectors ({sup 4}He in the transition regime, EJ301 still in the single-scattering regime) have comparable mass, but {sup 4}He detectors can be much larger depending on the number density. A six-tube 11-bar-pressure {sup 4}He detector prototype is built and tested. Individual electrical pulses from the detector are recorded using a 12-bit digitizer. Differences in pulse rise time and amplitudes, due to different energy loss of neutrons and gamma rays, are used for neutron/gamma separation. Several energy spectra are also obtained and analyzed.

  10. Metastability-exchange optical pumping of 3He for neutron polarizers

    International Nuclear Information System (INIS)

    Gentile, T.R.; Thompson, A.K.; Snow, W.M.

    1995-01-01

    Research is underway at NIST and IU to develop neutron polarizers that are based on polarized 3 He. Such polarizers rely on the strong spin dependence of the cross section for neutron capture by polarized 3 He. Two methods can produce the high density of polarized 3 He gas (10 19 -10 20 cm -3 ) required for an effective neutron polarizer: spin-exchange optical pumping, which is performed directly at high pressure (1-10 bar), and metastability-exchange optical pumping, in which the gas is polarized at low pressure (1 mbar) and then compressed. While we are pursuing both methods, progress in the metastable method will be discussed. The features of the metastable method are the high rate at which the gas can be polarized and the inherent separation of the optical pumping and target cells. In a landmark achievement, researchers at the Univ. of Mainz have developed a piston compressor that can fill a 130 cm 3 cell to a pressure of 7 bar of 45% polarized 3 He gas in 2 hours. We plan to develop a compressor and test it at the NIST Cold Neutron Research Facility. We have constructed a metastable-pumping apparatus at NIST and have obtained 76% polarization with a pumping rate of 1.2 x 10 18 atoms/sec in a 0.4 mbar, 270 cm 3 cell

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

    Science.gov (United States)

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

    2002-01-03

    Primordial nucleosynthesis after the Big Bang can be constrained by the abundances of the light elements and isotopes 2H, 3He, 4He and 7Li (ref. 1). The standard theory of stellar evolution predicts that 3He is also produced by solar-type stars, so its abundance is of interest not only for cosmology, but also for understanding stellar evolution and the chemical evolution of the Galaxy. The 3He abundance in star-forming (H II) regions agrees with the present value for the local interstellar medium, but seems to be incompatible with the stellar production rates inferred from observations of planetary nebulae, which provide a direct test of stellar evolution theory. Here we develop our earlier observations, which, when combined with recent theoretical developments in our understanding of light-element synthesis and destruction in stars, allow us to determine an upper limit for the primordial abundance of 3He relative to hydrogen: 3He/H = (1.1 +/- 0.2) x 10(-5). The primordial density of all baryons determined from the 3He data is in excellent agreement with the densities calculated from other cosmological probes. The previous conflict is resolved because most solar-mass stars do not produce enough 3He to enrich the interstellar medium significantly.

  12. Study of short-range correlation in nuclei via measurement of the 4He(,ee'pp) and 4He(e,e'pn) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Korover, Igor [Tel Aviv Univ., Ramat Aviv (Israel)

    2015-04-01

    This thesis reports on a simultaneous measurement of the 4He(e,e'p), 4He(e,e'pp), and 4He(e,e'pn) reactions at Q2 = 2 (GeV/c)2 and xB > 1 for an (e,e'p) missing momentum range of 400 to 830 MeV/c.

  13. Oxygen-sensitive 3He-MRI in bronchiolitis obliterans after lung transplantation

    International Nuclear Information System (INIS)

    Gast, Klaus K.; Biedermann, Alexander; Herweling, Annette; Schreiber, Wolfgang G.; Schmiedeskamp, Joerg; Mayer, Eckhard; Heussel, Claus P.; Markstaller, Klaus; Eberle, Balthasar; Kauczor, Hans-Ulrich

    2008-01-01

    Oxygen-sensitive 3 He-MRI was studied for the detection of differences in intrapulmonary oxygen partial pressure (pO 2 ) between patients with normal lung transplants and those with bronchiolitis obliterans syndrome (BOS). Using software developed in-house, oxygen-sensitive 3 He-MRI datasets from patients with normal lung grafts (n = 8) and with BOS (n = 6) were evaluated quantitatively. Datasets were acquired on a 1.5-T system using a spoiled gradient echo pulse sequence. Underlying diseases were pulmonary emphysema (n 10 datasets) and fibrosis (n = 4). BOS status was verified by pulmonary function tests. Additionally, 3 He-MRI was assessed blindedly for ventilation defects. Median intrapulmonary pO 2 in patients with normal lung grafts was 146 mbar compared with 108 mbar in patients with BOS. Homogeneity of pO2 distribution was greater in normal grafts (standard deviation pO2 34 versus 43 mbar). Median oxygen decrease rate during breath hold was higher in unaffected patients (-1.75 mbar/s versus -0.38 mbar/s). Normal grafts showed fewer ventilation defects (5% versus 28%, medians). Oxygen-sensitive 3 He-MRI appears capable of demonstrating differences of intrapulmonary pO2 between normal lung grafts and grafts affected by BOS. Oxygen-sensitive 3 He-MRI may add helpful regional information to other diagnostic techniques for the assessment and follow-up of lung transplant recipients. (orig.)

  14. 3He electron scattering sum rules

    International Nuclear Information System (INIS)

    Kim, Y.E.; Tornow, V.

    1982-01-01

    Electron scattering sum rules for 3 He are derived with a realistic ground-state wave function. The theoretical results are compared with the experimentally measured integrated cross sections. (author)

  15. High energy neutron recoil scattering from liquid 4He

    International Nuclear Information System (INIS)

    Holt, R.S.; Needham, L.M.; Paoli, M.P.

    1987-10-01

    The neutron recoil scattering from liquid 4 He at 4.2 K and 1.6 K has been observed for a momentum transfer of 150 A -1 using the Electron Volt Spectrometer on the pulsed neutron source, ISIS. The experiment yielded mean atomic kinetic energy values = 14.8 +- 3 K at 4.2 K and = 14.6 +- 3.2 K at 1.6 K in good agreement with values obtained at lower momentum transfers. (author)

  16. Non-uniform 3He polarization formed by multiple collisions of a fast 3He+ ion with polarized Rb vapor in a strong magnetic field

    International Nuclear Information System (INIS)

    Arimoto, Y.; Yonehara, K.; Yamagata, T.; Tanaka, M.

    2001-01-01

    We investigated the spatial distribution of a polarization in 3 He beam expected from a novel polarized 3 He ion source based on electron pumping, i.e., multiple electron capture and stripping collisions of an incident fast 3 He + ion with a polarized Rb vapor in a strong axial magnetic field. For this purpose, a Monte Carlo simulation was carried out for 19 keV 3 He + ions with varying Rb vapor thickness, magnetic field, and beam emittance. The calculated results showed a distribution of the 3 He polarization that we call a 'polarization hole', which has a low polarization area around the beam axis. The parameters characterizing the polarization hole, i.e., the polarization and radius of the hole, were found to depend on the Rb vapor thickness, the magnetic field, the beam size, and the angular divergence of the initial beam. These parameters were successfully reproduced with analytical functions deduced from a probability density function prescription. This provides a powerful tool to treat complex phenomena of multiple collisions in strong magnetic fields without performing time-consuming Monte Carlo calculations

  17. Spin-driven structural effects in alkali doped (4)He clusters from quantum calculations.

    Science.gov (United States)

    Bovino, S; Coccia, E; Bodo, E; Lopez-Durán, D; Gianturco, F A

    2009-06-14

    In this paper, we carry out variational Monte Carlo and diffusion Monte Carlo (DMC) calculations for Li(2)((1)Sigma(g) (+))((4)He)(N) and Li(2)((3)Sigma(u) (+))((4)He)(N) with N up to 30 and discuss in detail the results of our computations. After a comparison between our DMC energies with the "exact" discrete variable representation values for the species with one (4)He, in order to test the quality of our computations at 0 K, we analyze the structural features of the whole range of doped clusters. We find that both species reside on the droplet surface, but that their orientation is spin driven, i.e., the singlet molecule is perpendicular and the triplet one is parallel to the droplet's surface. We have also computed quantum vibrational relaxation rates for both dimers in collision with a single (4)He and we find them to differ by orders of magnitude at the estimated surface temperature. Our results therefore confirm the findings from a great number of experimental data present in the current literature and provide one of the first attempts at giving an accurate, fully quantum picture for the nanoscopic properties of alkali dimers in (4)He clusters.

  18. D-3He fuel cycles for neutron lean reactors

    International Nuclear Information System (INIS)

    Kernbichler, W.; Miley, G.H.; Heindler, M.

    1989-01-01

    The intrinsic potential of D-3He as a reactor fuel is investigated for a large range of 3He to D density ratios. A steady-state zero-dimensional reactor model is developed in which much care is attributed to a proper treatment of fast fusion products. Useful ranges of reactor parameters as well as temperature-density windows for driven and ignited operation are identified. Various figures of merit are calculated, such as power densities, net power production, neutron production, tritium load and radiative power. These results suggest several optimistic conclusions about the performance of D-3He as a reactor fuel

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

    Science.gov (United States)

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

    2005-01-01

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

  20. Implanted He retention and release from boronized layers

    International Nuclear Information System (INIS)

    Doyle, B.L.; Walsh, D.S.; Wampler, W.R.

    1992-01-01

    3 He has been implanted at an energy of 3 keV into amorphous hydrogenated boron-carbon (a-BC) films deposited by rf sputtering onto single crystal Si substrates. The initial composition of the films was analyzed by nuclear-enhanced backscattering spectrometry to be B 2 C with ∝20% H and ∝10% O. The areal density of the implanted and retained 3 He was measured in situ by a new ion beam analysis technique using the 3 He( 3 He, pp) three-body nuclear reaction. The He trapping or pumping efficiency at room temperature is only 3.4% for low fluence implants and the a-BC layer saturates with He at a fluence of 5x10 17 He/cm 2 . At this saturation fluence, only 3.1x10 15 He/cm 2 is retained in the film. Isochronal annealing of the implanted samples reveals a distributed release of implanted He at ∝200deg C, which corresponds to a trap activation energy of 1.65±0.25 eV. 3 He was trapped less efficiently at 250deg C than at room temperature and exhibited a saturated retention of 8.6x10 14 He/cm 2 . These results indicate that wall pumping should play only a minor role in the interpretation of the Textor He-pump experiment carried out earlier this year. The results also show that the unintentional deposition of a-Bc, onto He pumping plates could adversely affect the operation of such devices, and should therefore be avoided. (orig.)

  1. Conceptual design of D-3He FRC reactor 'ARTEMIS'

    International Nuclear Information System (INIS)

    Momota, H.; Ishida, A.; Kohzaki, Y.

    1991-07-01

    A comprehensive design study of the D- 3 He fueled field-reversed configuration (FRC) reactor 'ARTEMIS' is carried out for the purpose of proving its attractive characteristics and clarifying the critical issues for a commercial fusion reactor. The FRC burning plasma is stabilized and sustained in a steady equilibrium by means of a preferential trapping of D- 3 He fusion-produced energetic protons. A novel direct energy converter for 15MeV protons is also presented. On the bases of a consistent scenario of the fusion plasma production and simple engineering, a compact and simple reactor concept is presented. The design of the D- 3 He FRC power plant definitely offers the most attractive prospect for energy development. It is environmentally acceptable in view of radio-activity and fuel resources; and the estimated cost of electricity is low compared to a light water reactor. Critical issues concerning physics or engineering for the development of the D- 3 He FRC reactor are clarified. (author)

  2. Condensate fraction in superfluid 4He

    International Nuclear Information System (INIS)

    Olinto, A.C.

    1986-01-01

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

  3. Fine and hyperfine structure spectra of the ultra-violet 23S → 53P transition in 4He and 3He with a frequency doubled CW ring laser, detected via associative ionization

    International Nuclear Information System (INIS)

    Runge, S.; Pesnelle, A.; Perdrix, M.; Sevin, D.; Wolffer, N.; Watel, G.

    1982-01-01

    High resolution laser spectroscopy coupled to a sensitive method of detection via mass analysis of He + 2 ions produced in He(5 3 P) + He(1 1 S) collisions, is used to obtain the fine and hyperfine spectra of the ultra-violet He 2 3 S → 5 3 P transition. A cw tunable UV radiation around 294.5 nm is generated by intracavity frequency doubling a Rhodamine 6G single mode ring dye laser using an ADA crystal. Both spectra enable fine and hyperfine structures to be determined within a few MHz. The magnetic dipole coupling constant A of the 5 3 P term of 3 He is found to be -4326 +- 9 MHz (-0.1443 +- 0.0003 cm -1 ). (orig.)

  4. Diffusion of He interstitial and di-He cluster at grain boundaries in α-Fe

    International Nuclear Information System (INIS)

    Gao, F.; Heinisch, H.L.; Kurtz, R.J.

    2007-01-01

    A systematic molecular dynamics study of the diffusion mechanisms of He interstitial and di-He cluster at two representative interfaces has been carried out in α-Fe. The diffusion coefficient of a He interstitial and the effective migration energies were determined. The He atom diffuses along the Σ11 grain boundary one-dimensionally along specific directions, while it migrates two-dimensionally at low temperatures, and three-dimensionally at higher temperatures, in the Σ3 grain boundary. The di-He interstitial cluster can migrate rapidly along the Σ3 interface at low temperatures, but not at the Σ11 interface. It has been observed that a di-He interstitial cluster can kick out a self interstitial atom (SIA) at high temperatures, forming a He 2 V complex. The SIA migrates rapidly near interfaces, whereas the He 2 V complex is immobile at the temperatures considered. This small cluster may serve as the smallest nucleation for the formation of helium bubbles at interfaces

  5. Symmetry-protected topological superfluids and superconductors. From the basics to 3He

    International Nuclear Information System (INIS)

    Mizushima, Takeshi; Tsutsumi, Yasumasa; Kawakami, Takuto; Sato, Masatoshi; Ichioka, Masanori; Machida, Kazushige

    2016-01-01

    In this article, we give a comprehensive review of recent progress in research on symmetry-protected topological superfluids and topological crystalline superconductors, and their physical consequences such as helical and chiral Majorana fermions. We start this review article with the minimal model that captures the essence of such topological materials. The central part of this article is devoted to the superfluid 3 He, which serves as a rich repository of novel topological quantum phenomena originating from the intertwining of symmetries and topologies. In particular, it is emphasized that the quantum fluid confined to nanofabricated geometries possesses multiple superfluid phases composed of the symmetry-protected topological superfluid B-phase, the A-phase as a Weyl superfluid, the nodal planar and polar phases, and the crystalline ordered stripe phase. All these phases generate noteworthy topological phenomena, including topological phase transitions concomitant with spontaneous symmetry breaking, Majorana fermions, Weyl superfluidity, emergent supersymmetry, spontaneous edge mass and spin currents, topological Fermi arcs, and exotic quasiparticles bound to topological defects. In relation to the mass current carried by gapless edge states, we also briefly review a longstanding issue on the intrinsic angular momentum paradox in 3 He-A. Moreover, we share the current status of our knowledge on the topological aspects of unconventional superconductors, such as the heavy-fermion superconductor UPt 3 and superconducting doped topological insulators, in connection with the superfluid 3 He. (author)

  6. Recent {sup 3}He radio frequency heating experiments on JET

    Energy Technology Data Exchange (ETDEWEB)

    Van Eester, D. [Association Euratom-Belgian State, LPP-ERM/KMS, TEC, Brussels (Belgium); Imbeaux, F.; Joffrin, E. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France)] [and others

    2003-07-01

    Various ITER relevant experiments using {sup 3}He in a majority D plasma were performed in the recent JET campaigns. Two types can be distinguished: dedicated studies of the various RF heating scenarios which rely on the presence of {sup 3}He, and physics studies using RF heating as a working tool to provide a tunable heat source. As the success of a number of these experiments depended on the capability to keep the {sup 3}He concentration fixed, real time control of the {sup 3}He concentration was developed and used. This paper presents a brief overview of the results obtained, zooms in on some of the more interesting recent findings and discusses some of the theoretical background. (authors)

  7. Direct elastic and inelastic processes produced in the case of He+-He for 3 KeV00

    International Nuclear Information System (INIS)

    Bordenave-Montesquieu, Daniele.

    1980-12-01

    The He + on He collision has been studied by the energy loss method in the 3 to 50 KeV energy range and 0.25 to 3 0 angle range. A detailed description of the experimental device, which has been built for this purpose, is made. Direct elastic and inelastic cross sections are then obtained by integration. A single theoretical model is given, which explains the main features of the elastic differential cross section behaviour [fr

  8. Spectroscopic study of near closed-shell nuclei Z = 50, by means of the ({sup 3}He,d) and (d, {sup 3}He) reactions on all even tin isotopes, and the ({sup 3}He, d) reaction on the A = 113 and A = 115 indium isotopes; Etude spectroscopique des noyaux au voisinage de la couche fermee Z = 50, au moyen des reactions ({sup 3}He, d) et (d, {sup 3}He) sur tous les isotopes pairs de l'etain, et de la reaction ({sup 3}He, d) sur les isotopes 113, 115 de l'indium

    Energy Technology Data Exchange (ETDEWEB)

    Harar, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-01

    A systematic study of ({sup 3}He, d) reactions at 18 MeV incident energy and (d, {sup 3}He) reactions at 22 MeV incident energy on {sup 112,114,116,118,120,122,124}Sn is presented. The distorted wave Born approximation (DWBA) is used to extract informations on (a) the transferred angular momentum l{sub p}, (b) the change of parity and (c) the spectroscopic factor. We have investigated the influence of the proton-neutron residual interaction on the spread of the pure proton configuration (particle or hole), and on the observed level sequence. Experimental results and predictions of the Kisslinger and Sorensen model are in reasonable agreement. A study of {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn reactions shows strong experimental evidence that the proton particle hole components are weak in the first excited states of tin nuclei. Furthermore, highly excited states ({approx} 4 to 6 MeV) having a simple structure with one predominant particle-hole configuration have been located. (authors) [French] Nous presentons une etude systematique des reactions ({sup 3}He, d) a 18 MeV et (d, {sup 3}He) a 22 MeV sur {sup 112,114,116,118,120,122,124}Sn. L'approximation des ondes deformees (DWBA) est utilisee pour obtenir des informations sur le moment angulaire transfere l{sub p}, sur le changement de parite et le facteur spectroscopique. Nous avons etudie l'influence de l'interaction residuelle proton-neutron sur la repartition de l'intensite a une seule particule ou trou de proton, et sur les sequences des niveaux observes. Les resultats experimentaux et les previsions theoriques du modele de Kisslinger et Sorensen sont en assez bon accord. L'etude des reactions {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn apporte la preuve experimentale que les composantes particule - trou de protons des premiers etats excites des noyaux residuels sont faibles. Elle permet aussi de localiser des niveaux a une energie d'excitation elevee ({approx} 4 a 6 MeV), ayant une structure simple a

  9. Spectroscopic study of near closed-shell nuclei Z = 50, by means of the ({sup 3}He,d) and (d, {sup 3}He) reactions on all even tin isotopes, and the ({sup 3}He, d) reaction on the A = 113 and A = 115 indium isotopes; Etude spectroscopique des noyaux au voisinage de la couche fermee Z = 50, au moyen des reactions ({sup 3}He, d) et (d, {sup 3}He) sur tous les isotopes pairs de l'etain, et de la reaction ({sup 3}He, d) sur les isotopes 113, 115 de l'indium

    Energy Technology Data Exchange (ETDEWEB)

    Harar, S. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-01

    A systematic study of ({sup 3}He, d) reactions at 18 MeV incident energy and (d, {sup 3}He) reactions at 22 MeV incident energy on {sup 112,114,116,118,120,122,124}Sn is presented. The distorted wave Born approximation (DWBA) is used to extract informations on (a) the transferred angular momentum l{sub p}, (b) the change of parity and (c) the spectroscopic factor. We have investigated the influence of the proton-neutron residual interaction on the spread of the pure proton configuration (particle or hole), and on the observed level sequence. Experimental results and predictions of the Kisslinger and Sorensen model are in reasonable agreement. A study of {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn reactions shows strong experimental evidence that the proton particle hole components are weak in the first excited states of tin nuclei. Furthermore, highly excited states ({approx} 4 to 6 MeV) having a simple structure with one predominant particle-hole configuration have been located. (authors) [French] Nous presentons une etude systematique des reactions ({sup 3}He, d) a 18 MeV et (d, {sup 3}He) a 22 MeV sur {sup 112,114,116,118,120,122,124}Sn. L'approximation des ondes deformees (DWBA) est utilisee pour obtenir des informations sur le moment angulaire transfere l{sub p}, sur le changement de parite et le facteur spectroscopique. Nous avons etudie l'influence de l'interaction residuelle proton-neutron sur la repartition de l'intensite a une seule particule ou trou de proton, et sur les sequences des niveaux observes. Les resultats experimentaux et les previsions theoriques du modele de Kisslinger et Sorensen sont en assez bon accord. L'etude des reactions {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn apporte la preuve experimentale que les composantes particule - trou de protons des premiers etats excites des noyaux residuels sont faibles. Elle permet aussi de localiser des niveaux a une energie d'excitation elevee ({approx} 4 a 6 Me

  10. The γ-decays of 210Po-levels from the (3He,d*γγ)-reaction

    International Nuclear Information System (INIS)

    Klein, H.; Wiedenhoever, I.; Tiesler, H.; Meise, H.; Fitzler, A.; Dewald, A.; Thomas, H.G.; Weisshaar, D.; Brentano, P. von

    1999-01-01

    An in-beam experiment with the subcoulomb reaction 209 Bi( 3 He,d * γγ) 210 Po at 20.5 MeV was performed with two EUROBALL CLUSTER detectors in Cologne. It closed the gap between the low energy levels of the level-scheme and the high energy levels found in 209 Bi( 3 He,d) 210 Po and 208 Pb( 4 He,t) 210 Po particle experiments. New branchings have been found and the ( 3 He, d * γγ) reaction below the coulomb-barrier has been used successfully. (orig.)

  11. The nuclear reaction n + 3He -> 1H + 3H as proximity reaction

    International Nuclear Information System (INIS)

    Hilber, H.C.

    1982-01-01

    The present thesis tries to give by means of the nuclear reaction n + 3 He -> 1 H + 3 H as proximity reaction on the three-particle system 3 He + 9 Be -> 1 H + 3 H + 8 Be an experimental verification to the second term of a multiple scattering series. The study of these rescattering effects is of great interest for the present theory of the final-state interaction. At three incident energies (7.08 MeV, 8.98 MeV, and 6.37 MeV) to detector telescopes identify the exit channel of the three-particle system in list-mode coincidence experiments according to protons and tritons. Peaks on the kinematical curves occur. The detailed study of their kinematic behaviour allows to exclude the inconcurrence to the proximity reaction lying cascade decays via intermediate states in 4 He, 9 B, and 11 B. Regarding the Coulomb interaction the experimental results can be also explained in the sense of the classical kinematics by the proximity model. (orig.) [de

  12. Superfluid density and heat capacity measurements of 4He in porous gold

    International Nuclear Information System (INIS)

    Yoon, J.; Chan, M.

    1995-01-01

    Superfluid density of full pore 4 He as well as thin film 4 He confined in porous gold were measured as a function of temperature. The superfluid transition temperature of full pore was found to be 2.156 K. In both cases power law dependence on reduced temperature was found and the exponent was found to be the same as that of bulk 4 He. Porous gold is made by electrochemically leaching out silver from silver-gold alloy. The porous gold sample the authors fabricated has porosity of 55 with a diameter of 250 angstrom. Electron microscope picture shows that the structure of porous gold is exceedingly similar to that of Vycor. Heat capacity measurement of full pore 4 He in porous gold is in progress

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

    Science.gov (United States)

    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.

  14. 8He-6He: a comparative study of electromagnetic fragmentation reactions

    International Nuclear Information System (INIS)

    Meister, M.; Richter A.; Schrieder, G.; Simon, H.; Markenroth, K.; Jonson, B.; Nyman, G.; Zhukov, M.V.

    2001-11-01

    Dissociation of a 227 MeV/u 8 He beam in a lead target has been studied in a kinematically complete experiment. The results are compared with similar data from the well-known halo nucleus 6 He. Coulomb-nuclear interference in the inelastic channel gives evidence for a I π = 1 - resonance in 8 He at E x =4.15 MeV. The deduced B(E1) value of 0.38±0.07 e 2 fm 2 indicates a uniform distribution of the four neutrons around the α particle core. (orig.)

  15. 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)

    Energy Technology Data Exchange (ETDEWEB)

    Lara-Castells, María Pilar de, E-mail: Pilar.deLara.Castells@csic.es; Aguirre, Néstor F. [Instituto de Física Fundamental (C.S.I.C.), Serrano 123, E-28006 Madrid (Spain); Stoll, Hermann [Institut für Theoretische Chemie, Universität Stuttgart, D-70550 Stuttgart (Germany); Mitrushchenkov, Alexander O. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Mateo, David; Pi, Martí [Department ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona (Spain)

    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)].

  16. Sputtering of solid deuterium by He-ions

    DEFF Research Database (Denmark)

    Schou, Jørgen; Stenum, B.; Pedrys, R.

    2001-01-01

    Sputtering of solid deuterium by bombardment of 3He+ and 4He+ ions was studied. Some features are similar to hydrogen ion bombardment of solid deuterium, but for the He-ions a significant contribution of elastic processes to the total yield can be identified. The thin-film enhancement is more pro...... pronounced than that for hydrogen projectiles in the same energy range....

  17. Saffold Virus Type 3 (SAFV-3) Persists in HeLa Cells

    Science.gov (United States)

    Himeda, Toshiki; Hosomi, Takushi; Okuwa, Takako; Muraki, Yasushi; Ohara, Yoshiro

    2013-01-01

    Saffold virus (SAFV) was identified as a human cardiovirus in 2007. Although several epidemiological studies have been reported, they have failed to provide a clear picture of the relationship between SAFV and human diseases. SAFV genotype 3 has been isolated from the cerebrospinal fluid specimen of patient with aseptic meningitis. This finding is of interest since Theiler’s murine encephalomyelitis virus (TMEV), which is the closely related virus, is known to cause a multiple sclerosis-like syndrome in mice. TMEV persistently infects in mouse macrophage cells in vivo and in vitro, and the viral persistence is essential in TMEV-induced demyelinating disease. The precise mechanism(s) of SAFV infection still remain unclear. In order to clarify the SAFV pathogenicity, in the present study, we studied the possibilities of the in vitro persistent infection of SAFV. The two distinct phenotypes of HeLa cells, HeLa-N and HeLa-R, were identified. In these cells, the type of SAFV-3 infection was clearly different. HeLa-N cells were lyticly infected with SAFV-3 and the host suitable for the efficient growth. On the other hand, HeLa-R cells were persistently infected with SAFV-3. In addition, the SAFV persistence in HeLa-R cells is independent of type I IFN response of host cells although the TMEV persistence in mouse macrophage cells depends on the response. Furthermore, it was suggested that SAFV persistence may be influenced by the expression of receptor(s) for SAFV infection on the host cells. The present findings on SAFV persistence will provide the important information to encourage the research of SAFV pathogenicity. PMID:23308162

  18. The nucleation of vorticity by ions in superfluid 4He

    International Nuclear Information System (INIS)

    Muirhead, C.M.; Vinen, W.F.; Donnelly, R.J.

    1985-01-01

    The theory developed in Part I is extended to include a discussion of nucleation by negative ions in the presence of dissolved 3 He at a concentration such that at a low temperature the negative ion bubble is likely to have adsorbed on its surface either one or two 3 He atoms. It is argued that the adsorbed 3 He atom can change the nucleation rate for two reasons: the atom can modify the perturbation applied to the helium at the surface of the ions; and it can act as a source of energy. The second of these effects is explored in some detail. It is shown that the 3 He atom is probably less strongly bound to the ion than it would be to the core of a vortex line; furthermore the atom adsorbed onto the surface of the ion can exist in a number of excited states (Shikin states), which are thermally populated even at quite low temperatures. Therefore, when nucleation of a vortex takes place, the 3 He atom might move from the ion surface to the core of the vortex or simply from one Shikin state to another of lower energy; in either case there is a release of energy. The existence of this energy release means, first, that nucleation becomes energetically possible at a reduced ionic velocity and secondly, that the energy barrier opposing nucleation is reduced in size. Therefore the critical velocity for vortex nucleation is reduced, and, for a given supercritical velocity, the rate of nucleation is increased. Addition of a second 3 He atom would have a similar effect. Further experiments are required to check the detailed predictions of the theory. (author)

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  20. He reemission implanted in metals

    International Nuclear Information System (INIS)

    Tanabe, T.

    2014-01-01

    Highlights: • Observation of He reemission of various metals under He + implantation at wide temperature range. • Materials examined are aluminum (Al), Nickel (Ni) and molybdenum (Mo). • He reemission is quite temperature dependent and different with materials. • Three metals show similar dependence on temperature normalized with respective melting point. • He reemission is successfully correlated with He behavior in metals. - Abstract: Helium (He) reemission of Al, Ni and Mo under energetic He implantation (10–30 keV) in wide temperature range is studied to understand behavior of implanted He in correlation with structure changes. The reemission behavior is categorized into 4 different temperature ranges with the normalized temperature (T m ) to the melting point of each metal. At elevated temperatures (well above ∼0.6 T m ), interstitial He atoms and/or He-vacancy (ies) clusters can migrate remaining no structure change and showing smooth reemission without any burst. Between ∼0.25 and 0.6 T m , He reemission always accompanies significant structure modification. For ∼04–0.6 T m , implanted He coalesce to make bubbles and the bubbles can move to the surface. Bubble migration accompanies materials flow to the surface resulting in fuzz surface or columnar structure, depending on implantation flux. Slower bubble motion at ∼0.25–0.4 prohibits the material migration. Instead the bubbles coalesce to grow large and multi-layered blistering appears as periodic reemission behavior. Below ∼0.25 T m , He migration is too slow for bubbles to grow large, but bubble density increases up to a certain fluence, where neighboring bubbles start to coalesce. Accordingly, He release is mostly caused by mechanical failure or blister rapture. With increasing fluence, all defects (bubbles and dislocation loops) tangle or inter connected with neighboring defects and accordingly He migration to the surface along the tangled or connected defects is enhanced

  1. Experimental investigation and numerical simulation of 3He gas diffusion in simple geometries: implications for analytical models of 3He MR lung morphometry.

    Science.gov (United States)

    Parra-Robles, J; Ajraoui, S; Deppe, M H; Parnell, S R; Wild, J M

    2010-06-01

    Models of lung acinar geometry have been proposed to analytically describe the diffusion of (3)He in the lung (as measured with pulsed gradient spin echo (PGSE) methods) as a possible means of characterizing lung microstructure from measurement of the (3)He ADC. In this work, major limitations in these analytical models are highlighted in simple diffusion weighted experiments with (3)He in cylindrical models of known geometry. The findings are substantiated with numerical simulations based on the same geometry using finite difference representation of the Bloch-Torrey equation. The validity of the existing "cylinder model" is discussed in terms of the physical diffusion regimes experienced and the basic reliance of the cylinder model and other ADC-based approaches on a Gaussian diffusion behaviour is highlighted. The results presented here demonstrate that physical assumptions of the cylinder model are not valid for large diffusion gradient strengths (above approximately 15 mT/m), which are commonly used for (3)He ADC measurements in human lungs. (c) 2010 Elsevier Inc. All rights reserved.

  2. Deeply virtual Compton scattering off "4He

    International Nuclear Information System (INIS)

    Hattawy, M.

    2015-01-01

    The "4He nucleus is of particular interest to study nuclear GPDs (Generalized Parton Distributions) as its partonic structure is described by only one chirally-even GPD. It is also a simple few-body system and has a high density that makes it the ideal target to investigate nuclear effects on partons. The experiment described in this thesis is JLab-E08-24, which was carried out in 2009 by the CLAS collaboration during the 'EG6' run. In this experiment, a 6 GeV longitudinally-polarized electron beam was scattered onto a 6 atm "4He gaseous target. During this experiment, in addition to the CLAS detector, a Radial Time Projection Chamber (RTPC), to detect low-energy nuclear recoils, and an Inner Calorimeter (IC), to improve the detection of photons at very forward angles, were used. We carried out a full analysis on our 6 GeV dataset, showing the feasibility of measuring exclusive nuclear Deeply Virtual Compton Scattering (DVCS) reactions. The analysis included: the identification of the final-state particles, the DVCS event selection, the π"0 background subtraction. The beam-spin asymmetry was then extracted for both DVCS channels and compared to the ones of the free-proton DVCS reaction, and to theoretical predictions from two models. Finally, the real and the imaginary parts of the "4He CFF (Compton Form Factor) HA have been extracted. Different levels of agreement were found between our measurements and the theoretical calculations. This thesis is organized as follows: In chapter 1, the available theoretical tools to study hadronic structure are presented, with an emphasis on the nuclear effects and GPDs. In chapter 2, the characteristics of the CLAS spectrometer are reviewed. In chapter 3, the working principle and the calibration aspects of the RTPC are discussed. In chapter 4, the identification of the final-state particles and the Monte-Carlo simulation are presented. In chapter 5, the selection of the DVCS events, the background subtraction, and uncertainty

  3. Construction of a 400 kV accelerator plant with a measuring apparatus for the investigation of nuclear reactions and testing of the Barshay-Temmer isospin theorem by the reaction 3H(3He,d)4He at energies E(3He) < 840 keV

    International Nuclear Information System (INIS)

    Quast, U.

    1973-01-01

    In order to test the Barshay-Temmer isospin theorem by the reaction 3 H( 3 He,d) 4 He, the angular distributions of the relative differential cross section were recorded at anti E 3 = 291, 369, 600 and 800 keV using a solid Ti-tritium target. A d-p discrimination enabled a practically background-free detection of the deuterons. The relative errors were of 0.5% to 3%. A 400 kV Sames accelerator plant was equiped and supplemented by an ion beam conducting system and energy analyser system. The angular distributions are almost symmetrical around 90 0 in the centre of gravity system at all energies. By developing according to Legendre polynomials, the small forward-backward asymmetry could be determined which has its greatest value Wsub(max) = -0.013 +- 0.005 at anti E 3 sub(He) = 291 keV. The possible causes for the found violation of the Barstray-Temmer theorem are discussed. Using a simple model of the isospin mixture of two states, the results of this work can be described as interferences in the transition over an isospin allowed (Jsup(π),T) = (1 - ,0) and an overlapping, forbidden (2 + ,1) state in the compound nucleus 6 Li whose positions and widths can be estimated to be from the cross section course of the reaction Esub(x)( 6 Li) approximately 17 MeV, Gamma approximately 1.6 MeV, Jsup(π) = 1 - , T = 0, Esub(x)( 6 Li) approximately 16.2 MeV, Gamma approximately 0.5 MeV, Jsup(π) = 2 + , T = 1. (orig./LH) [de

  4. He{sup 3+}{sub 2} and HeH{sup 2+} molecular ions in a strong magnetic field: The Lagrange-mesh approach

    Energy Technology Data Exchange (ETDEWEB)

    Olivares Pilón, Horacio, E-mail: holivare@ulb.ac.be [Physique Quantique, CP 165/82, Université Libre de Bruxelles, B 1050 Brussels (Belgium)

    2012-04-09

    Accurate calculations for the ground state of the molecular ions He{sup 3+}{sub 2} and HeH{sup 2+} placed in a strong magnetic field B≳10{sup 2} a.u. (≈2.35×10{sup 11} G) using the Lagrange-mesh method are presented. The Born–Oppenheimer approximation of zero order (infinitely massive centers) and the parallel configuration (molecular axis parallel to the magnetic field) are considered. Total energies are found with 9–10 s.d. The obtained results show that the molecular ions He{sup 3+}{sub 2} and HeH{sup 2+} exist at B>100 a.u. and B>1000 a.u., respectively, as predicted in Turbiner and López Vieyra (2007) while a saddle point in the potential curve appears for the first time at B∼80 a.u. and B∼740 a.u., respectively. -- Highlights: ► Application of the Lagrange-mesh method to two exotic molecular systems. ► He{sup 3+}{sub 2} and HeH{sup 2+} exist at B>100 a.u. and B>1000 a.u., respectively. ► Accurate results for the total energy. ► A saddle point in the potential appears at B∼80 a.u. and B∼740 a.u., respectively.

  5. Structure and dynamics of molecular complex He2*(a3Σu+) in condensed phases of helium

    International Nuclear Information System (INIS)

    Kafanov, S.G.; Parshin, A.Ya.; Tadoshchenko, I.A.

    2000-01-01

    The absorption spectra of the helium triplet metastable molecules in the a 3 Σ u + states in the liquid 4 He and 3 He by various pressures and in the 3 He dense gas are studied. The analysis of the spectrum, corresponding to the a 3 Σ u + → c 3 Σ g + transition, proves the conclusion on the availability of a microscopic bubble, surrounding the molecule in the liquid helium. Simple approximation of the wave function of the molecule valent electron is proposed and the bubble parameters under various experimental conditions are determined. The coefficient conditions are determined. The coefficient of the molecular recombination in the liquid 3 He and 4 He by different pressures and in the 3 He cold gas is experimentally determined. The obtained results agree well with the mutual recombination theory. It is shown, that molecular polarization in the helium condensed phases under the magnetic field effect does not lead to their mutual recombination [ru

  6. (, 3) Differential cross section of He

    Indian Academy of Sciences (India)

    The angular distribution of the five-fold differential cross section for the electron impact double ionization of He (21 ) and He (23 ) has been studied. The kinematical conditions for maxima/minima in the angular distribution for the two cases have been compared. The two-step process for the double ionization is found to ...

  7. Neutron production by deuteron breakup on 4He

    International Nuclear Information System (INIS)

    Schmidt, D.

    1994-10-01

    Neutron spectra of the deuteron breakup on 4 He have been measured at eight deuteron incident energies between 4.7 MeV and 12.1 MeV using the TOF method. The measurements carried out at angles of 0 deg, 5 deg and 10 deg were completed by measurements at 2.5 deg and 7.5 deg at some energies. The cross sections for these angles were reliably interpolated for the other energies. The normalization to absolute cross sections was carried out by reference to the well known data of the DD reaction. When a relative energy scale is introduced the spectral shape is almost angle-independent. It is shown that the use of the deuteron breakup on 4 He can considerably refine the correction for the deuteron breakup on deuterium in scattering experiments made with Monte Carlo simulations. (orig.)

  8. Emission spectra of Rb*Hen exciplexes in a cold 4He gas

    International Nuclear Information System (INIS)

    Hirano, K.; Enomoto, K.; Kumakura, M.; Takahashi, Y.; Yabuzaki, T.

    2003-01-01

    We report on the systematic observation of emission spectra of Rb * He n exciplexes (n=1,2,...,6), realized by exciting Rb atoms to the 5 2 P states (Rb * ) in a cold 4 He gas. The observed broad spectral components are assigned to Rb * He n (n=1-6) using theoretical spectra obtained from ab initio potential curves. The dynamics of the exciplex formation is discussed, based on the observed temperature dependence of the spectra. The He gas density dependence of the spectra of Rb * He is understood as a change in the population distribution over the vibrational levels. The present results are compared with our previous work with Cs [K. Enomoto et al., Phys. Rev. A 66, 042505 (2002)], and differences are explained in terms of the difference in the fine-structure splitting. Furthermore, we show the emission spectrum observed after the excitation of Rb in liquid He and conclude that it is the fluorescence from the exciplex Rb * He 6

  9. Results of the determination of He in cenozoic aquifers using the GC method.

    Science.gov (United States)

    Kotowski, Tomasz; Najman, Joanna

    2015-04-01

    Applications of the Helium (He) method known so far consisted mainly of 4He measurements using a special mass spectrometer. 4He measurements for groundwater dating purposes can be replaced by total He (3He+4He) concentration measurements because the content of 3He can be ignored. The concentrations of 3He are very low and 3He/4 He ratios do not exceed 1.0·10(-5) in most cases. In this study, the total He concentrations in groundwater were determined using the gas chromatographic (GC) method as an alternative to methods based on spectrometry measurement. He concentrations in groundwater were used for the determination of residence time and groundwater circulation. Additionally, the radiocarbon method was used to determine the value of the external He flux (JHe) in the study area. Obtained low He concentrations and their small variation within the ca. 65 km long section along which groundwater flows indicate that it is likely there is relatively short residence time and a strong hydraulic connection between the aquifers. The estimated residence time (ca. 3000 years) is heavily dependent on the great uncertainty of the He concentration resulting from the low concentrations of He, the external 4He flux value adopted for calculation purposes and the 14C ages used to estimate the external 4He flux. © 2015, National Ground Water Association.

  10. Progress in Polarized 3He Ion Source at RCNP

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  11. Differential cross section measurement for the 6Li(n,t)4He Reaction

    International Nuclear Information System (INIS)

    Zhang Guohui; Tang Guoyou; Chen Jinxiang; Shi Zhaomin

    2002-01-01

    The differential cross sections and integrated cross sections of the 6 Li(n,t) 4 He reaction were measured at 1.85 and 2.67 MeV by using a gridded ionization chamber. Neutrons were produced through the T(p, n) 3 He reaction. The absolute neutron flux was determined through the 238 U(n, f) reaction. Present results are compared with existing data

  12. Boron-coated straws as a replacement for 3He-based neutron detectors

    International Nuclear Information System (INIS)

    Lacy, Jeffrey L.; Athanasiades, Athanasios; Sun, Liang; Martin, Christopher S.; Lyons, Tom D.; Foss, Michael A.; Haygood, Hal B.

    2011-01-01

    US and international government efforts to equip major seaports with large area neutron detectors, aimed to intercept the smuggling of nuclear materials, have precipitated a critical shortage of 3 He gas. It is estimated that the annual demand of 3 He for US security applications alone is more than the worldwide supply. This is strongly limiting the prospects of neutron science, safeguards, and other applications that rely heavily on 3 He-based detectors. Clearly, alternate neutron detection technologies that can support large sensitive areas, and have low gamma sensitivity and low cost must be developed. We propose a low-cost technology based on long copper tubes (straws), coated on the inside with a thin layer of 10 B-enriched boron carbide ( 10 B 4 C). In addition to the high abundance of boron on Earth and low cost of 10 B enrichment, the boron-coated straw (BCS) detector offers distinct advantages over conventional 3 He-based detectors, and alternate technologies such as 10 BF 3 tubes and 10 B-coated rigid tubes. These include better distribution inside moderator assemblies, many-times faster electronic signals, no pressurization, improved gamma-ray rejection, no toxic or flammable gases, and ease of serviceability. We present the performance of BCS detectors dispersed in a solid plastic moderator to address the need for portal monitoring. The design adopts the outer dimensions of currently deployed 3 He-based monitors, but takes advantage of the small BCS diameter to achieve a more uniform distribution of neutron converter throughout the moderating material. We show that approximately 63 BCS detectors, each 205 cm long, distributed inside the moderator, can match or exceed the detection efficiency of typical monitors fitted with a 5 cm diameter 3 He tube, 187 cm long, pressurized to 3 atm.

  13. Boron-coated straws as a replacement for 3He-based neutron detectors

    Science.gov (United States)

    Lacy, Jeffrey L.; Athanasiades, Athanasios; Sun, Liang; Martin, Christopher S.; Lyons, Tom D.; Foss, Michael A.; Haygood, Hal B.

    2011-10-01

    US and international government efforts to equip major seaports with large area neutron detectors, aimed to intercept the smuggling of nuclear materials, have precipitated a critical shortage of 3He gas. It is estimated that the annual demand of 3He for US security applications alone is more than the worldwide supply. This is strongly limiting the prospects of neutron science, safeguards, and other applications that rely heavily on 3He-based detectors. Clearly, alternate neutron detection technologies that can support large sensitive areas, and have low gamma sensitivity and low cost must be developed. We propose a low-cost technology based on long copper tubes (straws), coated on the inside with a thin layer of 10B-enriched boron carbide ( 10B 4C). In addition to the high abundance of boron on Earth and low cost of 10B enrichment, the boron-coated straw (BCS) detector offers distinct advantages over conventional 3He-based detectors, and alternate technologies such as 10BF 3 tubes and 10B-coated rigid tubes. These include better distribution inside moderator assemblies, many-times faster electronic signals, no pressurization, improved gamma-ray rejection, no toxic or flammable gases, and ease of serviceability. We present the performance of BCS detectors dispersed in a solid plastic moderator to address the need for portal monitoring. The design adopts the outer dimensions of currently deployed 3He-based monitors, but takes advantage of the small BCS diameter to achieve a more uniform distribution of neutron converter throughout the moderating material. We show that approximately 63 BCS detectors, each 205 cm long, distributed inside the moderator, can match or exceed the detection efficiency of typical monitors fitted with a 5 cm diameter 3He tube, 187 cm long, pressurized to 3 atm.

  14. Collisional effects in He I lines and helium abundances in planetary nebulae

    International Nuclear Information System (INIS)

    Clegg, R.E.S.

    1987-01-01

    Attention is drawn to new, 19-state quantal calculations for collisional excitation by electron impact in neutral helium. Recommended empirical formulae are given for the collisional contribution to HeI recombination lines such as λλ4471, 5876 A in gaseous nebulae. Collisional ionization of metastable (2 3 S) He I is significant for high-temperature nebulae. Collisional transfers provide significant cooling in nebulae with low heavy-element abundances. Revised mean He/H ratios for three large samples of planetary nebulae are given. (author)

  15. Role of interfaces on the trapping of He in 2D and 3D Cu–Nb nanocomposites

    International Nuclear Information System (INIS)

    Lach, Timothy G.; Ekiz, Elvan H.; Averback, Robert S.; Mara, Nathan A.; Bellon, Pascal

    2015-01-01

    The role of interface structure on the trapping of He in Cu–Nb nanocomposites was investigated by comparing He bubble formation in nano-multilayers grown by PVD, nanolaminates fabricated by accumulative roll bonding (ARB), and 3D nanocomposites obtained by high pressure torsion (HPT). All samples were implanted with 1 MeV He ions at room temperature and characterized by cross section transmission electron microscopy (TEM). The critical He concentration leading to bubble formation was determined by correlating the He bubble depth distribution detected by TEM with the implanted He depth profile obtained by SRIM. The critical He dose per unit interfacial area for bubble formation was largest for the PVD multilayers, lower by a factor of ∼1.4 in the HPT nanocomposites annealed at 500 °C, and lower by a factor of ∼4.6 in the ARB nanolaminates relative to the PVD multilayers. The results indicate that the (111)FCC||(110)BCC Kurdjumov-Sachs (KS) interfaces predominant in PVD and annealed HPT samples provide more effective traps than the (112)KS interfaces predominant in ARB nanolaminates; however, the good trapping efficiency and high interface area of 3D HPT structures make them most attractive for applications. - Highlights: • Cu–Nb nanocomposites with varying interface structure were implanted with He. • PVD multilayers trap the most He per interfacial area before bubbles form. • ARB nanolaminates held ∼4.6 times less He relative to the PVD multilayers. • 3D nanocomposites with high interface area can trap more He than 2D nanocomposites. • Interface structure and interfacial area density play key role in trapping He.

  16. Small objects in superfluid 3He

    International Nuclear Information System (INIS)

    Rainer, D.; Vuorio, M.

    1977-02-01

    Distortions in the superfluid order parameter around a small object in 3 He are calculated together with the supercurrents and the angular momentum induced by it in the liquid. The forces acting on the impurity by the liquid texture structure are also considered. (author)

  17. Multi-nucleon pion absorption in the 4He(π+,ppp)n reaction

    International Nuclear Information System (INIS)

    Weber, P.; McAlister, J.; Olszewski, R.; Feltham, A.; Hanna, M.; Johnson, R.R.; Pavan, M.; Ponting, C.; Rozon, F.M.; Sevior, M.; Sossi, V.; Vetterli, D.; Humphrey, D.; Lolos, G.J.; Papandreou, Z.; Tacik, R.; Ottewell, D.; Sheffer, G.; Smith, G.R.; Mardor, Y.; May-Tal, S.

    1990-08-01

    Three-proton emission cross sections for the 4 He(π + ,ppp)n reaction were measured at an incident pion kinetic energy of T pi + =165 MeV over a wide angular range in a kinematically complete experiment. Angular correlations, missing momentum distributions and energy spectra are compared with three- and four-body phase space Monte Carlo calculations. The results provide strong evidence that most of the three-proton coincidences result from three-nucleon absorption. From phase-space integration the total three-nucleon absorption cross section is estimated to be σ 3N =4.8 ± 1.0 mb. The cross section involving four nucleons is small and is estimated to be σ 4N 4 He, multi-nucleon pion absorption seems to represent only a small fraction. (Author) (40 refs., 3 tabs., 15 figs.)

  18. Dissipation of flow in superfluid 3He-A

    International Nuclear Information System (INIS)

    Paalanen, M.A.; Osheroff, D.D.

    1980-01-01

    The first direct measurements of the dissipation due to flow are performed and the effects of that flow on the NMR properties of 3 He-A are studied. A temperature-independent critical velocity v/sub c/=0.52 mm/s is observed, above which a pressure difference proportional to v/sub s/-v/sub c/ developes across our flow orifice. simultaneously, the NMR frequency in 3 He-A is lowered by an amount also proportional to v/sub s/-v/sub c/, in contrast to current theoretical predictions

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

    Directory of Open Access Journals (Sweden)

    Sulkosky Vincent A.

    2016-01-01

    Full Text Available The 3He nucleus has become extremely important in the investigation of the neutron’s spin structure. When polarized, 3He acts as an effective polarized neutron target and hence facilitates our understanding of the neutron’s internal structure. However, to be used in this manner, our understanding of the internal structure of 3He is of extreme importance. As the precision of experiments has improved, the extraction of polarized neutron information from 3He leads to an ever larger share of the systematic uncertainty for these experiments. In these proceedings, I present a precise measurement of beam-target asymmetries in the He→3(e→ ,e′d${}^3\\overrightarrow {He} (\\vec e,e'd$ and He→3(e→,e′p${}^3\\overrightarrow {He} (\\vec e,e'p$ reactions. The former process is a uniquely sensitive probe of hadron dynamics in 3He and the structure of the underlying electromagnetic currents. The measurements have been performed around the quasi-elastic peak at Q2 = 0.25 (GeV/c2 and 0.35 (GeV/c2 for recoil momenta up to 270 MeV/c. The experimental apparatus, analysis and results were presented together with a comparison to state-of-the art Faddeev calculations.

  20. Faraday instability of crystallization waves in 4He

    International Nuclear Information System (INIS)

    Abe, H; Ueda, T; Morikawa, M; Saitoh, Y; Nomura, R; Okuda, Y

    2007-01-01

    Periodic modulation of the gravity acceleration makes a flat surface of a fluid unstable and standing waves are parametrically excited on the surface. This phenomenon is called Faraday instability. Since a crystal-superfluid interface of 4 He at low temperatures is very mobile and behaves like a fluid surface, Saarloos and Weeks predicted that Faraday instability of the crystallization waves exists in 4 He and that the threshold excitation for the instability depends on the crystal growth coefficient. We successfully observed the Faraday instability of the crystal-liquid interface at 160 mK. Faraday waves were parametrically generated at one half of the driving frequency 90 Hz. Amplitude of the Faraday wave becomes smaller at higher temperature due to decrease of the crystal growth coefficient and disappears above 200 mK

  1. Experimental research of the radiative capture of thermal neutrons in 3He

    International Nuclear Information System (INIS)

    Bystritskij, V.M.; Enik, T.L.; Gerasimov, V.V.; Grebenyuk, V.M.; Kobzev, A.P.; Kublikov, R.V.; Parzhitskij, S.S.; Pavlov, V.N.; Salamatin, A.V.; Shvetsov, V.N.; Slepnev, V.M.; Strelkov, A.V.; Zamyatin, N.I.; Bystritskij, V.M.; Filipowicz, M.; Nesvizhevskij, V.V.; Popov, N.P.; Wozniak, J.

    2006-01-01

    A project of an experiment on measurement of the cross sections of radiative thermal neutron capture by 3 He nuclei with production of one and two γ-quanta (n th + 3 He→α+γ(2γ)) is presented. The interest in studying the processes is dictated by the following factors: a possibility of obtaining information on parameters of the nucleon N-N potential and structure of exchange meson currents; a possibility of verifying the model of the mechanism for nucleon capture by the nucleus 3 He in the low-energy region; necessity to solve some questions existing in astrophysics. The experiment is planned to be carried out on the PF1B beam of the ILL reactor (Grenoble). The target is a hollow cylinder of pure aluminium (diam. 140x80 mm) filled with 3 He and 4 He (background experiment) at the pressure 2 atm. Registration of the γ-quanta is carried out by four BGO crystal (diam. 100x70 mm) detectors. According to the calculations the experiment, with 400-500 h of the PF1B beam running time, will allow cross sections for the above reactions to be measured for the first time with an accuracy of 2-4% (one-quantum process) and 7-10 % (two-quantum process), which quite meets the purposes of the project

  2. Study of the (3He,t) reaction on 48Ca at 82 MeV

    International Nuclear Information System (INIS)

    Tanabe, T.; Yasue, M.; Sato, K.; Soga, F.; Igarashi, M.; Ogino, K.; Kadota, Y.; Saito, Y.; Shimokoshi, F.

    1978-01-01

    The reactions ( 3 He,t), ( 3 He, 3 He), ( 3 He,α) and ( 3 He,d) on 48 Ca have been studied at an incident energy of 82 MeV. The obtained angular distributions for the ( 3 He,t) reaction have been analyzed in terms of second-order DWBA theory, using a zero-range approximation. The relative ratio of the cross sections for the excitation of the fsub(7/2)f -1 sub(7/2) multiplets of 48 Sc could not be explained consistently by the one-step charge-exchange process only. However, the ratio was reproduced in order of magnitude by second-order DWBA calculations including the effect of two-step processes, such as ( 3 He-α-t) and ( 3 He-d-t) channels. The effects of the d- and α-channels on the elastic scattering of 3 He from 48 Ca were also examined in the framework of second-order full finite-range DWBA. (Auth.)

  3. Production of e(+)e(-) pairs in proton-deuteron capture to He-3

    NARCIS (Netherlands)

    Korchin, AY; Van Neck, D; Waroquier, M; Scholten, O; Dieperink, AEL

    1998-01-01

    The process p + d He-3 + gamma * at intermediate energies is described using a covariant and gauge-invariant model, and a realistic pd(3)He vertex, Both photodisintegration of He-3 and proton-deuteron capture with production of e(+)e(-) pairs are studied, and results for cross sections and response

  4. The ground state energy of 3He droplet in the LOCV framework

    International Nuclear Information System (INIS)

    Modarres, M.; Motahari, S.; Rajabi, A.

    2012-01-01

    The (extended) lowest order constrained variational method was used to calculate the ground state energy of liquid helium 3 ( 3 He) droplets at zero temperature. Different types of density distribution profiles, such as the Gaussian, the Quasi-Gaussian and the Woods-Saxon were used. It was shown that at least, on average, near 20 3 He atoms are needed to get the bound state for 3 He liquid droplet. Depending on the choice of the density profiles and the atomic radius of 3 He, the above estimate can increase to 300. Our calculated ground state energy and the number of atoms in liquid 3 He droplet were compared with those of Variational Monte Carlo method, Diffusion Monte Carlo method and Density Functional Theory, for which a reasonable agreement was found.

  5. Photoemission of protons from 4He in the Δ-resonance region

    International Nuclear Information System (INIS)

    Wichmann, R.; Ahrens, J.; Arends, H.J.; Beck, R.; Galler, G.; Huenger, A.; Kraus, A.; MacGregor, I.J.D.; Peise, J.; Seitz, B.; Schmitz, M.; Schneider, M.; Selke, O.; Schumacher, M.; Wissmann, F.

    1996-01-01

    High resolution proton energy spectra from the 4 He(γ,p) reaction have been measured with tagged photons in the range E γ =130-525 MeV using the large Mainz NaI(Tl) spectrometer at Θ lab p =37.1 circle. Three separate reaction channels were identified, viz. 4 He(γ,p)t two-body breakup, 4 He photodisintegration via two-nucleon photon absorption processes and the quasifree pion production channel. Differential cross sections are presented for each of these channels as a function of photon energy. The sum of the two-nucleon photon absorption and the quasifree pion production differential cross sections, in the CM system, resembles that of the corresponding free-nucleon differential cross section when Fermi motion is taken into account. (orig.)

  6. Study on the mechanism of the 3He+p→p+p+d reaction at 3He momentum of 5 GeV/c

    International Nuclear Information System (INIS)

    Blinov, A.V.; Chuvilo, I.V.; Drobot, V.V.

    1985-01-01

    The mechanism of the reaction 3 He+p → p+p+d is studied making use of the ITEP 80-cm liquid-hydrogen bubble chamber exposed to the beam of 5 GeV/c 3 He nuclei. The reaction cross sections is equal to 20.6+-0.3 mb. The phase space regions associated with quasi-free scattering (QFS) and final state interaction (FSI) are selected. Angular, mass and momentum distributions of the reaction products are obtained in the entire kinematically allowed range. The experimental data in the QFS region are compared with theoretical calculations based on the simplest pole diagram approximation. The 3 He and deuteron wave functions (WF) correspond to the realistic Reid potential. The D-wave components of these WF are taken into account. The absolute value of the cross section and shape of the distributions are described as a whole reasonably enough in the frame of the considered model in the kinematical region where FSI may be neglected

  7. The 3He spectral function in light-front dynamics

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo

    2016-01-01

    Full Text Available A distorted spin-dependent spectral function for 3He is considered for the extraction of the transverse-momentum dependent parton distributions in the neutron from semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, where final state interactions are taken into account. The generalization of the analysis to a Poincaré covariant framework within the light-front dynamics is outlined.

  8. Preconceptual engineering design for the APT 3He Target/Blanket concept

    International Nuclear Information System (INIS)

    Mensink, D.L.

    1994-01-01

    A preconceptual engineering design has been developed for the 3 He Target/Blanket (T/B) System for the Accelerator Production of Tritium Project. This concept uses an array of pressure tubes containing tungsten rods for the neutron spallation source and 3 He gas contained in a metal tank and blanket tubes as the tritium production material. The engineering design is based on a physics model optimized for efficient tritium production. Principle engineering consideration were: provisions for cooling all materials including the 3 He gas; containment of the gas and radionuclides; remote handling; material compatibility; minimization of 3 He, D 2 O, and activated waste; modularity; and manufacturability. The design provides a basis for estimating the cost to implement the system

  9. Spectrophotometry study of the symbiotic stars He2-417, He2-467 and He2-468

    International Nuclear Information System (INIS)

    Navarro, S.; Costero, R.; Serrano, P.G.A.; Carrasco, L.

    1987-01-01

    A spectrophotometric study of He2-417, 467 and 468 is made. Their spectra show mainly emission lines of H I, He I and He II, as well as absorption bands characteristic of late-type stars. No forbidden lines were detected in the spectra of the objects. We report the line intensity ratios relative to Hβ and compare them with those previously reported in the literature. Some line ratios have varied in He2-417 and 467, the two objects with previous observations. (Author)

  10. The average equilibrium charge-states of heavy ions with Z > 60 stripped in He and H2

    International Nuclear Information System (INIS)

    Oganessian, Yu.T.; Lobanov, Yu.V.; Popeko, A.G.; Abdullin, F.Sh.; Kharitonov, Yu.P.; Ledovskoy, A.A.; Tsyganov, Yu.S.

    1991-01-01

    The equilibrium charges of heavy ions (61 < Z < 101) with energies from 5 to 100 MeV stripped in He and H2 have been measured. New empirical formulae for the average charge state are presented. (orig.)

  11. Autoionization spectra of He excited by fast (MeV) H+, He+, and Li/sup n+/ (n = 1,2,3) ions

    International Nuclear Information System (INIS)

    Schneider, D.; Arcuni, P.; Bruch, P.; Stoeffler, W.

    1983-01-01

    Autoionization spectra of He following excitation by 1 to 3 MeV H + , He + , and Li/sup n+/ (n = 1,2,3) have been measured as a function of observation angle. The (2p 2 ) 1 D and (2s2p) 1 P resonances have been examined and a strong dependence on projectile velocities, charge state and observation angle was found

  12. First doubly polarised photoproduction on 3He at the photon beam of MAMI

    International Nuclear Information System (INIS)

    Aguar Bartolome, Patricia

    2010-11-01

    A first experiment with a polarised 3 He target was carried out in July 2009 at the MAMI accelerator in Mainz in a photon energy range between 200 MeV and 800 MeV. The aim of this measurement was to investigate the Gerasimov-Drell-Hearn sum rule on the neutron. The use of the data obtained with the polarised 3 He target, compared to existing data on the deuteron, gives a complementary and more direct access to the neutron, due to the spin structure of the 3 He. The measurement of the helicity dependence of the inclusive total photoabsorption cross section required a beam of tagged circularly polarised photons incident on the longitudinally polarised 3 He target. The data were taken using the 4π Crystal Ball photon spectrometer in combination with TAPS as a forward wall and complemented by a threshold Cherenkov detector used to on-line suppress the background from electromagnetic events. The development and preparation of the different components of the 3 He experimental setup was an important part of this work and are described in detail in this thesis. The detector system and the analysis method were tested by the measurement of the unpolarised total inclusive photoabsorption cross section on liquid hydrogen. The results obtained are in good agreement with previous published data. Preliminary results of the unpolarised total photoabsorption cross section, as well as the helicity dependent photoabsorption cross section difference on 3 He compared with several theoretical models will also be presented. (orig.)

  13. Development of data acquisition system for CSNS 3He detector

    International Nuclear Information System (INIS)

    Zhao Dongxu; Zhang Hongyu

    2012-01-01

    This paper introduces the research and development of data acquisition system of CSNS 3 He detector prototype. This system provides high performance data acquisition capability of CSNS 3 He detector, as well as several performance tests of electronics prototype. This data acquisition system establishes foundation for the later data acquisition development. (authors)

  14. OCS in He droplets

    Energy Technology Data Exchange (ETDEWEB)

    Grebenev, V.

    2000-06-01

    Phenomenon of superfluidity of para-hydrogen (pH{sub 2}){sub 1-17} and helium {sup 4}He{sub 1-7000} systems doped with an OCS chromophore molecule was investigated in this work. The study of such systems became possible after the development of the depletion spectroscopy technique in helium droplets. The droplets can be easily created and doped with up to 100 particles such as OCS, para-hydrogen or ortho-hydrogen molecules and {sup 4}He atoms. The measured infrared depletion spectra give the information about the temperature of the droplets and their aggregate state. The depletion spectrum of OCS in pure {sup 4}He droplets was comprehensively studied. The rovibrational OCS spectrum shows well resolved narrow lines. The spectrum is shifted to the red relative to the corresponding gas phase spectrum and the rotational constant of OCS in {sup 4}He droplet is three times smaller than that for free molecule. Different models of OCS rotation in the helium environment were discussed. It was shown that the shapes of the rovibrational lines are defined mainly by inhomogeneous broadening due to the droplet size distribution. The sub-rotational structure of the OCS rovibrational lines was revealed in microwave-infrared double resonance experiments. This structure arises due to the interaction of the OCS with the He environment. However, the information obtained in the experiments was not enough to understand the nature of this interaction. (orig.)

  15. Comment on "Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis".

    Science.gov (United States)

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

    2007-08-31

    Eggleton et al. (Reports, 8 December 2006, p. 1580) reported on a deep-mixing mechanism in low-mass stars caused by a Rayleigh-Taylor instability that destroys all of the helium isotope 3He produced during the star's lifetime. Observations of 3He in planetary nebulae, however, indicate that some stars produce prodigious amounts of 3He. This is inconsistent with the claim that all low-mass stars should destroy 3He.

  16. The He+H¯→He p¯+e+ rearrangement

    Science.gov (United States)

    Todd, Allan C.; Armour, Edward A. G.

    2006-06-01

    In this paper, we present a summary of our work in progress on calculating cross sections for the He+H¯→He p¯+e+ rearrangement process in He H¯ scattering. This has involved a study of the system He p¯ within the Born-Oppenheimer (BO) approximation using the Rayleigh-Ritz variational method. This work has been reported in [A.C. Todd, E.A.G. Armour, J. Phys. B 38 (2005) 3367] and is summarised here. Similar calculations are in progress for the He+H¯ entrance channel. We intend to use the entrance channel and rearrangement channel wave functions to obtain the cross sections for the rearrangement using the distorted wave Born approximation T-matrix method described elsewhere in these proceedings [E.A.G. Armour, S. Jonsell, Y. Liu, A.C. Todd, these Proceedings, doi:10.1016/j.nimb.2006.01.049].

  17. Theory of the surface-induced magnetism in liquid 3He

    International Nuclear Information System (INIS)

    Jichu, Hisao; Kuroda, Yoshihiro

    1982-01-01

    A theory of the surface-induced magnetism of liquid 3 He confined in a restricted geometry is presented. In a general model, three different types of contributions to the effective exchange interactions among spins of the 3 He atoms in a solid layer adsorbed on a substrate are distinguished on the basis of the second order perturbation theory; one is from a direct process and the others are mediated by the spins of the 3 He atoms in the remaining bulk liquid. By using a simplified model, the exchange constants are calculated to find that an RKKY-type indirect exchange interaction appears to be most dominant and to explain the observed ferromagnetic tendency. (author)

  18. The SLAC high-density gaseous polarized 3He target

    International Nuclear Information System (INIS)

    Johnson, J.R.; Chupp, T.E.; Smith, T.B.; Cates, G.D.; Driehuys, B.; Middleton, H.; Newbury, N.R.; Hughes, E.W.; Meyer, W.

    1995-01-01

    A large-scale high-pressure gaseous 3 He polarized target has been developed for use with a high-intensity polarized electron beam at the Stanford Linear Accelerator Center. This target was used successfully in an experiment to study the spin structure of the neutron. The target provided an areal density of about 7x10 21 nuclei/cm 2 and operated at 3 He polarizations between about 30% and 40% for the six-week duration of the experiment. ((orig.))

  19. Charge transfer processes in collisions of Si{sup 4+} ions with He atoms at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, R. [Hitotsubashi Univ., Tokyo (Japan). Computer Center; Watanabe, A. [Dept. of Information Sciences, Ochanomizu Univ., Tokyo (Japan); Sato, H. [Graduate School of Humanities and Sciences, Ochanomizu Univ., Tokyo (Japan); Gu, J.P.; Hirsch, G.; Buenker, R.J. [Wuppertal Univ. (Gesamthochschule) (Germany). Lehrgebiet Theoretische Chemie; Kimura, M. [Graduate School of Science and Engineering, Yamaguchi Univ., Ube (Japan); Stancil, P.C. [Georgia Univ., Athens, GA (United States). Dept. of Physics

    2001-07-01

    Charge transfer in collisions of Si{sup 4+} ions with He atoms below 100 keV/u is studied by using a molecular orbital representation within both the semiclassical and quantal representations. Single transfer reaction Si{sup 4+} + He {yields} Si{sup 3+} + He{sup +} has been studied by a number of theoretical investigations. In addition to the reaction (1), the first semiclassical MOCC calculations are performed for the double transfer channel Si{sup 4+} + He {yields} Si{sup 2+} + He{sup 2+}. Nine molecular states that connect both with single and double electron transfer processes are considered in the present model. Electronic states and corresponding couplings are determined by the multireference single- and double- excitation configuration interaction method. The present cross sections tie well with the earlier calculations of Stancil et al., (1997) at lower energies, but show a rather different magnitude from those of Bacchus-Montabonel and Ceyzeriat, (1998). The present rate constant is found to be significantly different from the experimental finding of Fang and Kwong, (1996) at 4,600 K, and hence does not support the experiment. (orig.)

  20. Measurement of double polarized asymmetries in quasi-elastic processes ${}^3\\vec{He}(\\vec{e},e' d)$ and ${}^3\\vec{He}(\\vec{e},e' p)$

    Energy Technology Data Exchange (ETDEWEB)

    Mihovilovic, Miha [Univ. of Ljubljana (Slovenia)

    2012-01-01

    This thesis is dedicated to a study of a spin-isospin structure of the polarized 3He. First, an introduction to the spin structure of 3He is given, followed by a brief overview of past experiments. The main focus of the thesis is the E05-102 experiment at Jefferson Lab, in which the reactions ${}^3\\vec{He}(\\vec{e},e' d)$ and ${}^3\\vec{He}(\\vec{e},e' p)$ in the quasi-elastic region were studied. The purpose of this experiment was to better understand the effects of the S'- and D-state contributions to the 3He ground-state wave-functions by a precise measurement of beam-target asymmetries Ax and Az in the range of recoil momenta from 0 to about 300 MeV/c. The experimental equipment utilized in these measurements is described, with special attention devoted to the calibration of the hadron spectrometer, BigBite. Results on the measured asymmetries are presented, together with first attempts at their comparison to the state-of-the art Faddeev calculations. The remaining open problems and challenges for future work are also discussed.

  1. Effective mass of liquid 3He using the melting curve data

    International Nuclear Information System (INIS)

    Chaddah, P.; Simmons, R.O.; Illinois Univ., Urbana

    1980-01-01

    Measurements of dp/dt and of the liquid and solid molar volumes along the melting curve of 3 He can be used to obtain information about the Fermi liquid parameter Esub(f) = p 2 sub(f)/2m* of liquid 3 He. Data at temperatures reasonably far above the Neel temperature of the solid, but low enough so that the first finite-temperature correction term in Fermi liquid theory is not large are used. It is shown that in spite of uncertainties in the solid 3 He entropy because of uncertainties in the knowledge of the exchange mechanism, the melting curve data provide a check on the different sets of values for m* quoted in literature. The possible effect of ground state vacancies, whose existence in BCC 3 He has been speculated on this analysis is also discussed. (author)

  2. Dynamics of photoexcited Ba+ cations in 4He nanodroplets

    International Nuclear Information System (INIS)

    2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Leal, Antonio; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Pi, Martí; Zhang, Xiaohang; Drabbels, Marcel; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" >Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo

    2016-01-01

    We present a joint experimental and theoretical study on the desolvation of Ba + cations in 4 He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba + cations and Ba + He n exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba + He n exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba + . In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba + cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba + cations or exciplexes, even when relaxation pathways to lower lying states are included.

  3. Realization of a broad band neutron spin filter with compressed, polarized 3He gas

    International Nuclear Information System (INIS)

    Surkau, R.; Otten, E.W.; Steiner, M.; Tasset, F.; Trautmann, N.

    1997-01-01

    The strongly spin dependent absorption of neutrons in nuclear spin polarized 3 -2pt vector He opens the possibility to polarize beams of thermal and epithermal neutrons. An effective 3 He neutron spin filter (NSF) requires high 3 He nuclear polarization as well as a filter thickness corresponding to a gas amount of the order of 1 bar l. We realized such a filter using direct optical pumping of metastable 3 He * atoms in a 3 He plasma at 1 mbar. Metastable exchange scattering transfers the angular momentum to the whole ensemble of 3 He atoms. At present 3 x 10 18 3 He-atoms/s are polarized up to 64%. Subsequent polarization preserving compression by a two stage compressor system enables to prepare NSF cells of about 300 cm 3 volume with 3 bar of polarized 3 He within 2 h. 3 He polarizations up to 53% were measured in a cell with a filter length of about 15 cm. By this cell a thermal neutron beam from the Mainz TRIGA reactor was polarized. A wavelength selective polarization analysis by means of Bragg scattering revealed a neutron polarization of 84% at a total transmission of 12% for a neutron wavelength of 1 A. (orig.)

  4. The static structure factor of liquid 4He: some new aspects

    International Nuclear Information System (INIS)

    Khalil, K.Y.

    1986-08-01

    The thesis is concerned with three complementary problems. The first deals with a new interpretation of the elusive nature of the roton. This is motivated by the observation that the 'rotonic' minimum in the dispersion curve, which is intimately related to the principal peak of the static structure factor, is a common feature not only for He II but also for He I and almost all other condensed systems. The second problem concerns the precise asymptotic behaviour of the pair correlation function for liquid sup 4 He, whose Fourier transform is essentially the long-wavelength liquid structure factor. The third problem deals with the implications of this new formulation as related to Bose-Einstein condensation and superfluidity, as well as to other physical properties of the system. The thesis concludes with a partial list of open problems and with two possible extensions, including a complete development of an exceedingly simple method for determining the second virial coefficient of the sup 4 He gas over a wide temperature range. 122 refs., 2 figs., 5 tabs. (A.M.H)

  5. Questioning the observation of laser-assisted ionization in fast collisions of He(2 /sup 1,3/S) with He

    International Nuclear Information System (INIS)

    Gillen, K.T.

    1989-01-01

    In four recent papers Pradel et al. [Phys. Rev. Lett. 54, 2600 (1985); Phys. Rev. A 35, 1062 (1987)] and Monchicourt et al. [Phys. Rev. A 33, 3515 (1986); Chem. Phys. Lett. 152, 336 (1988)] give arguments claiming the observation of laser-assisted ionization of the short-lived collision complex formed during collisions of He/sup */(2 /sup 1,3/S) with He. However, estimates of the relative sizes of the assisted and unassisted ion signals observed make it very unlikely that laser-assisted ionization has been observed in those experiments. Collisional excitation to higher He/sup */ states, followed by (single-photon) ionization of the excited states, seems a more likely explanation at all energies considered

  6. Finite Forward Acceptance Angles for Single Electron Capture by ^3He^2+ Ions in He and H_2

    Science.gov (United States)

    Mawhorter, Rj; Greenwood, J.; Smith; Chutjian, A.

    2004-05-01

    Perhaps surprisingly, electron capture scattering angles of a few degrees or more are observed for slow ions impacting light targets. Gas cells must be designed with this in mind. Indeed the difference between small acceptance angle results(W.L. Nutt, et al., J. Phys. B 8), 1457 (1978) and the larger acceptance-angle studies of both Kusakabe, et al.(T. Kusakabe, et al., J. Phys. Soc. Japan 59), 1218 (1990) and our group at JPL (presented here; energy range 0.33-4.67 keV/amu) for ^3He^2+ in H2 can be ascribed to this effect. Olson and Kimura(R. E. Olson and M. Kimura, J. Phys. B 15), 4231 (1982) have modeled the problem theoretically. We use existing differential cross section data(D. Bordenave-Montesquieu and R. Dagnac, J. Phys. B 27), 543 1994) for both H_2/ D2 and ^4He targets to calculate realistic acceptance angles. The resulting small total cross section corrections provide reliable absolute results for these benchmark systems. This work was carried out at JPL/Caltech, and was supported through agreement with NASA.

  7. Charge-symmetry-breaking effects from phase-shift analysis of elastic πsup(+-4)He scattering

    International Nuclear Information System (INIS)

    Khankhasayev, M.Kh.; Nichitiu, F.; Sapozhnikov, M.G.

    1986-01-01

    A phase-shift analysis of elastic πsup(+-4)He scattering at energies 20-160 MeV was performed to determine pure hadronic phase shifts. No statistically significant difference between the hadronic phase shifts deduced from π +4 He and π -4 He scattering was observed. (orig.)

  8. Coherent photoproduction of π+ on 3He in the (3,3) resonance region

    International Nuclear Information System (INIS)

    Boyard, J.-L.

    1975-01-01

    An experimental study of the 3 He(γ,π + ) 3 H reaction has been performed in the (3,3) resonance region with a bremsstrahlung photon beam and a liquid 3 He target. A magnetic spectrometer followed by a wire chamber analyzed the momentum of the outgoing pions and defined their emission angle. The tritons were detected in coincidence with the pions by two methods: a telescope of thin plastic scintillators below 40MeV; or a magnetic spectrometer followed by a series of plastic scintillators for higher energies. The experiment shows two main features: at a fixed four-momentum transfer q 2 , the resonance is shifted towards lower energies, this shift increasing with q 2 ; at a fixed angle, but variable q 2 , the minimum of the charge form factor observed in the elastic scattering of electrons on 3 He does not appear. Calculations explain partly these two effects [fr

  9. Antiproton interaction with 4He as a test of GUT cosmology

    International Nuclear Information System (INIS)

    Chechetkin, V.M.; Khlopov, M.Yu.; Zeldovich, Ya.B.

    1982-01-01

    A new possibility of checking some GUT models is suggested, basing on the analysis of their cosmological consequences and the experimental study of the anti p 4 He interaction. The study of annihilation of antiprotons with 4 He may provide limits on the possible amount of antimatter in the early Universe, limits on the probability of formation of primordial black holes and restrictions on the GUT parameters determining the properties of domains of antimatter

  10. Estimation of admixture of twelve quark bag state in sup 4 He nucleus

    CERN Document Server

    Mosallem, A M

    2002-01-01

    The p sup 4 He elastic scattering at the energy range from 0.695 to 393 GeV is analyzed in the framework of the Glauber theory. The Glauber amplitudes were evaluated using isospin-averaged nucleon-nucleon amplitudes and the sup 4 He wave function as a superposition of the Gaussian functions. The values of the calculated differential cross sections usually exceed the experimental ones. In order to overcome the discrepancy, it is assumed following to the paper by L. G. Dakno and N. N. Nikolaev that the ground state wave function of sup 4 He has an admixture of a twelve quark bag. Neglecting all transition amplitudes, the p - 12q bag scattering amplitude was chosen in a simple Gaussian form.The inclusion of the 12q bag leads to decreasing the p sup 4 He differential cross section and to a shift of the dip position to a large values of t what is needed for a successful description of the experimental data. While fitting the data it is found that the weight of the 12q bag state in the ground state of the sup 4 He ...

  11. Immunohistochemical localization of HE4 in benign, borderline, and malignant lesions of the ovary.

    Science.gov (United States)

    Georgakopoulos, Penelope; Mehmood, Saira; Akalin, Ali; Shroyer, Kenneth R

    2012-11-01

    Despite advances in the development of novel methods to improve treatment, ovarian carcinoma is still the leading cause of gynecologic cancer death in the United States and other industrialized nations. Improvements in the clinical outcome of ovarian cancer will be achieved if methods can be developed to enable the detection of these tumors at the earliest possible stage. Thus, it is critically important to identify and validate new biomarkers of ovarian cancer. HE4 expression was defined by immunohistochemical analysis of a wide range of benign, borderline, and malignant ovarian lesions, including serous, endometrioid, mucinous, and clear cell lesions of the ovary and in primary tubal carcinomas and the normal fallopian tube. At the cellular level, HE4 was highly expressed in malignant ovarian tumors and in a wide range of benign and borderline ovarian lesions. In addition, HE4 was highly expressed in primary fallopian tube carcinomas and benign fallopian tubal epithelial cells. These results support the conclusion that HE4 is widely expressed in most benign, borderline, and malignant lesions of the ovary and the fallopian tube. The detection of HE4 expression at high levels in some benign lesions and normal tissues suggests that HE4 could have limited specificity as a marker of ovarian or tubal carcinoma. Furthermore, the relatively weak expression that was observed in many ovarian carcinomas indicates that HE4 could fail to detect some cases of primary or recurrent disease.

  12. High-pressure 3He gas scintillation neutron spectrometer

    International Nuclear Information System (INIS)

    Derzon, M.S.; Slaughter, D.R.; Prussin, S.G.

    1985-10-01

    A high-pressure, 3 He-Xe gas scintillation spectrometer has been developed for neutron spectroscopy on D-D fusion plasmas. The spectrometer exhibits an energy resolution of (121 +- 20 keV) keV (FWHM) at 2.5 MeV and an efficiency of (1.9 +- 0.4) x 10 -3 (n/cm 2 ) -1 . The contribution to the resolution (FWHM) from counting statistics is only (22 +- 3 keV) and the remainder is due predominantly to the variation of light collection efficiency with location of neutron events within the active volume of the detector

  13. The unbound isotopes {sup 9,10}He

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, H.T. [Fundamental Fysik, Chalmers Tekniska Hoegskola, S-412 96 Goeteborg (Sweden); Aksyutina, Yu. [Fundamental Fysik, Chalmers Tekniska Hoegskola, S-412 96 Goeteborg (Sweden); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Aumann, T.; Boretzky, K. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Borge, M.J.G. [Instituto Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Chatillon, A. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Chulkov, L.V. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Kurchatov Institute, RU-123182 Moscow (Russian Federation); Cortina-Gil, D. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); University of Santiago de Compostela, 15706 Santiago de Compostela (Spain); Datta Pramanik, U. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Emling, H. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Forssen, C. [Fundamental Fysik, Chalmers Tekniska Hoegskola, S-412 96 Goeteborg (Sweden); Fynbo, H.O.U. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Geissel, H.; Ickert, G. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Jonson, B., E-mail: Bjorn.Jonson@chalmers.s [Fundamental Fysik, Chalmers Tekniska Hoegskola, S-412 96 Goeteborg (Sweden); Physics Department, CERN, CH-1211 Geneve 23 (Switzerland); Kulessa, R. [Instytut Fizyki, Universytet Jagiellonski, PL-30-059 Krakow (Poland); Langer, C. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Lantz, M. [Fundamental Fysik, Chalmers Tekniska Hoegskola, S-412 96 Goeteborg (Sweden); LeBleis, T.; Mahata, K. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany)

    2010-10-15

    The unbound nuclei {sup 9}He and {sup 10}He have been produced in proton-knockout reactions from a 280 MeV/u {sup 11}Li beam impinging on a liquid hydrogen target at the ALADIN-LAND setup at GSI. Information on their nuclear structure has been obtained from the relative-energy spectra, {sup 8}He+n and {sup 8}He+2n, employing reaction models incorporating the structure of {sup 11}Li. The {sup 8}He+n relative-energy spectrum is dominated by a strong peak-like structure at low energy, which may be interpreted within the effective-range approximation as the result of an s-wave interaction with a neutron scattering length of -3.17(66) fm. This spectrum also shows evidence for resonance states at 1.33(8) MeV and at 2.4 MeV above the {sup 8}He+n threshold. It is argued that the s-state might not be the {sup 9}He ground state. For {sup 8}He+n+n, the analysis of the relative-energy spectrum gives two alternative possibilities for an interpretation: either a narrow resonance at 1.42(10) MeV ({Gamma}=1.11(76) MeV) superimposed on a correlated background, or two overlapping resonances, a ground state at 1.54(11) MeV ({Gamma}=1.91(41) MeV) together with an excited state at 3.99(26) MeV ({Gamma}=1.64(89) MeV). The two possible interpretations are discussed.

  14. Boron-coated straws as a replacement for {sup 3}He-based neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lacy, Jeffrey L., E-mail: jlacy@proportionaltech.com [Proportional Technologies, Inc., 8022 El Rio Street, Houston, TX 77054 (United States); Athanasiades, Athanasios; Sun, Liang; Martin, Christopher S.; Lyons, Tom D.; Foss, Michael A.; Haygood, Hal B. [Proportional Technologies, Inc., 8022 El Rio Street, Houston, TX 77054 (United States)

    2011-10-01

    US and international government efforts to equip major seaports with large area neutron detectors, aimed to intercept the smuggling of nuclear materials, have precipitated a critical shortage of {sup 3}He gas. It is estimated that the annual demand of {sup 3}He for US security applications alone is more than the worldwide supply. This is strongly limiting the prospects of neutron science, safeguards, and other applications that rely heavily on {sup 3}He-based detectors. Clearly, alternate neutron detection technologies that can support large sensitive areas, and have low gamma sensitivity and low cost must be developed. We propose a low-cost technology based on long copper tubes (straws), coated on the inside with a thin layer of {sup 10}B-enriched boron carbide ({sup 10}B{sub 4}C). In addition to the high abundance of boron on Earth and low cost of {sup 10}B enrichment, the boron-coated straw (BCS) detector offers distinct advantages over conventional {sup 3}He-based detectors, and alternate technologies such as {sup 10}BF{sub 3} tubes and {sup 10}B-coated rigid tubes. These include better distribution inside moderator assemblies, many-times faster electronic signals, no pressurization, improved gamma-ray rejection, no toxic or flammable gases, and ease of serviceability. We present the performance of BCS detectors dispersed in a solid plastic moderator to address the need for portal monitoring. The design adopts the outer dimensions of currently deployed {sup 3}He-based monitors, but takes advantage of the small BCS diameter to achieve a more uniform distribution of neutron converter throughout the moderating material. We show that approximately 63 BCS detectors, each 205 cm long, distributed inside the moderator, can match or exceed the detection efficiency of typical monitors fitted with a 5 cm diameter {sup 3}He tube, 187 cm long, pressurized to 3 atm.

  15. Elastic and charge-exchange scattering of pions from 3He and 3H

    International Nuclear Information System (INIS)

    Gibson, B.F.; Hess, A.T.

    1976-04-01

    We have examined (1) the elastic scattering of pions from the isodoublet 3 He and 3 H and (2) the single charge-exchange reaction 3 H(π + ,π 0 ) 3 He using a formalism which incorporates the π-N multiple scattering to all orders. Emphasis is placed on numerical results which illustrate those features of the differential cross sections that are expected to be of interest to the experimentalist. Realistic nuclear densities corresponding to the form factors of elastic electron scattering were used. Charge-exchange cross sections are presented in terms of angular distributions for both the π 0 and the recoil nucleus. In elastic scattering, Coulomb-nuclear interference effects are significant at incident pion kinetic energies of less than 100 MeV; form factor effects are apparent at large momentum transfer. Comparison of data and theory for π + - 3 He with that for π - - 3 He (or the conjugate π + - 3 H) will provide a test of the convergence of the fixed scatterer, multiple-scattering formalism utilized in this report. 21 figures

  16. The mobility of negative ions in superfluid 3He

    International Nuclear Information System (INIS)

    Solomaa, M.

    1982-01-01

    This article reviews recent experimental and theoretical work on the mobility of negative ions in the superfluid A and B phases of liquid 3 He. In the normal Fermi liquid at temperatures below approximately 50 mK and also in the superfluid close to the superfluid transition temperature, Tsub(c), the mobility of a negative ion may simply be considered as limited by the elastic scattering of 3 He quasiparticles. This explains the constancy of the ion mobility in the normal phase. However, underlying the rapid increase of the measured mobility in the superfluid phases there is a subtle quantum-mechanical scattering effect. Detailed solutions of the 3 He quasiparticle-negative ion scattering process in the pair-correlated state provide a simple physical picture of an energy-dependent forward-peaking phenomenon. This yields quantitative theoretical results for the ion mobility in the quasi-isotropic B phase and for the ion mobility tensor in the anisotropic A phase which agree with the experimental data. (author)

  17. SPATA4 Counteracts Etoposide-Induced Apoptosis via Modulating Bcl-2 Family Proteins in HeLa Cells.

    Science.gov (United States)

    Jiang, Junjun; Li, Liyuan; Xie, Mingchao; Fuji, Ryosuke; Liu, Shangfeng; Yin, Xiaobei; Li, Genlin; Wang, Zhao

    2015-01-01

    Spermatogenesis associated 4 (SPATA4) is a testis-specific gene first cloned by our laboratory, and plays an important role in maintaining the physiological function of germ cells. Accumulated evidence suggests that SPATA4 might be associated with apoptosis. Here we established HeLa cells that stably expressed SPATA4 to investigate the function of SPATA4 in apoptosis. SPATA4 protected HeLa cells from etoposide-induced apoptosis through the mitochondrial apoptotic pathway, in the way that SPATA4 suppressed decrease of the mitochondrial membrane potential, the release of cytochrome c, and subsequent activation of caspase-9 and -3. We further demonstrated that SPATA4 upregulated anti-apoptotic members of Bcl-2 family proteins, Bcl-2, and downregulated the pro-apoptotic member of Bcl-2 family proteins, Bax. Knockdown of SPATA4 in HeLa/SPATA4 cells could partially rescue expression levels of bcl-2 and bax. In conclusion, SPATA4 protects HeLa cells against etoposide-induced apoptosis through the mitochondrial apoptotic pathway. Our findings provide further evidence that SPATA4 plays a role in regulating apoptosis.

  18. Separable interactions and liquid 3He

    International Nuclear Information System (INIS)

    Nijhoff, F.W.

    1984-01-01

    In this thesis, the different phases of liquid 3 He are studied in the presence and absence of magnetic field. It offers microscopic calculations starting from BCS hamiltonians with some additional terms (Zeeman-term to include the magnetic field; an Hubbard-term to include spin fluctuations). A systematic determination of the phase diagram is presented. (Auth.)

  19. Spin-exchange and spin-destruction rates for the 3He-Na system

    International Nuclear Information System (INIS)

    Borel, P.I.; Soegaard, L.V.; Svendsen, W.E.; Andersen, N.

    2003-01-01

    Optically pumped Na is used as a spin-exchange partner to polarize 3 He. Polarizations around 20% have routinely been achieved in sealed spherical glass cells containing 3 He, N 2 , and a few droplets of Na. An optical technique has been developed to determine the Na- 3 He spin-exchange rate coefficient. By monitoring the Na spin relaxation ''in the dark,'' the average Na-Na spin-destruction cross section at 330 degree sign C is estimated to be around 5x10 -19 cm 2 . This value is 2-5 (15-30) times smaller than the previously reported values for the K-K (Rb-Rb) spin-relaxation cross section. In the temperature range 310-355 degree sign C the spin-exchange rate coefficient is found to be (6.1±0.6)x10 -20 cm 3 /s with no detectable temperature dependence. This value is in good agreement with a previous theoretical estimate reported by Walker and it is only slightly lower than the corresponding Rb- 3 He spin-exchange rate coefficient. The total Na- 3 He spin-destruction rate coefficient is, within errors, found to be the same as the Na- 3 He spin-exchange rate coefficient, thereby indicating that the maximum possible photon efficiency may approach unity for the Na- 3 He system. A technique, in which a charge-coupled device camera is used to take images of faint unquenched fluorescence light, has been utilized to allow for an instantaneous determination of the sodium number densities during the rate coefficient measurements

  20. Inclusive measurements of pion double charge exchange and inelastic scattering on 3He

    International Nuclear Information System (INIS)

    Yuly, M.E.

    1993-06-01

    A measurement was made at the Los Alamos Meson Physics Facility (LAMPF) of the doubly differential cross sections for three inclusive pion reactions on 3 He: π - double charge exchange (DCX), and π + and π - inelastic scattering. The cross sections for DCX were measured at incident energies of 120, 180, 210, and 240 MeV, and at angles of 25, 50, 80, 105, and 130 degrees, while inelastic scattering cross sections were measured at 120, 180, and 240 MeV and scattering angles of 50, 80, 105, and 130 degrees. The final pion energy spectrum was measured from 10 MeV up to the kinematic limit. In the Δ resonance region, where the isospin T = 3/2 channel dominates, the inelastic π - scattering should be almost entirely from the lone neutron in 3 He. The π + inelastic scattering was expected to have significant contributions from both single and double scattering, because the T = 3/2 channel favors π + -p scattering from the two protons in 3 He. The 3 He DCX spectra are similar to those observed for DCX in 4 He. The forward angle double peaks can be understood as a consequence of sequential single charge exchange (SSCX). Calculations using the SSCX model are in rough agreement with the measured shape of the 3 He DCX spectra. The doubly differential cross sections measured for the inelastic scattering reactions exhibit a strong enhancement near the kinematics for free π - -p scattering. The ratios of π + to π - scattering cross sections may indicate multiple scattering, as well as the agreement of the low outgoing energy part of the π + inelastic scattering spectra with the corresponding properly scaled DCX spectra. A distorted-wave impulse-approximation (DWIA) calculation of the quasielastic cross sections has been performed and a comparison made with the measured inelastic cross sections

  1. The scattering of polarized neutrons from statically polarized solid {sup 3}He

    Energy Technology Data Exchange (ETDEWEB)

    Haase, D.G.; Keith, C.D.; Gould, C.R.; Seely, M.L. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Huffman, P.R.; Roberson, N.R.; Tornow, W.; Wilburn, W.S. [Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)]|[Duke University, Durham, NC 27708-0308 (United States)

    1998-01-11

    We have constructed a 0.4 mole solid {sup 3}He target, cryogenically polarized at 12 mK in a field of 7 T. The 0.04 atoms/b target reached a polarization of 38% in 35 h. Such a target may be applied to any experiment which is tolerant of the large ambient magnetic field and which produces target heating of less than a microwatt. High energy neutron and photon scattering experiments meet these requirements. The target`s figure of merit for neutron transmission measurement exceeds that of polarized gas targets by greater than 35. At the Triangle Universities Nuclear Laboratory we have used the target to measure the total cross section differences {Delta}{sigma}{sub T} and {Delta}{sigma}{sub L} for incident polarized neutrons of energies 2-8 MeV. The cross section difference is sensitive to the excited state structure of the n-{sup 3}He system. The results have been compared to a recent R-matrix analysis of A=4 scattering and reaction data, and provide support for the {sup 4}He level scheme derived from that analysis. (orig.). 11 refs.

  2. Remeasurement of p/suby/ for the 2H(d, n)3He reaction and its bearing on the reported f-wave admixture of the lowest 2- state in 4He

    International Nuclear Information System (INIS)

    Tornow, W.; Skubic, S.E.; Byrd, R.C.; Lisowski, P.W.; Walter, R.L.

    1976-01-01

    The polarization of neutrons from the reaction 2 H(d, n) 3 He has been measured for a deuteron energy E/subd/ = 2.44 MeV at emission angles of 45degree and 55degree (lab). The polarization values are discussed in relation both to previously reported discrepant data and to measured differences between p/suby/ and A/suby/ in the reaction 3 H(p, n) 3 He

  3. One- and two-electron processes in collisions of heavy ions with H2 and He

    International Nuclear Information System (INIS)

    Richard, P.; Hall, J.; Shinpaugh, J.L.; Sanders, J.M.; Tipping, T.N.; Zouros, T.J.M.; Lee, D.H.; Schmidt-Boecking, H.

    1987-01-01

    In this paper we present a description of the apparatus and results for experiments involving one- and two-electron processes in collisions of heavy ions with H 2 and He. The experiments were performed using one-electron and bare projectiles. In the first section we describe the measurement of pure ionization of one-electron projectiles by H 2 targets and compare with previous results for He targets. We also present the results for one-electron capture by the projectile from H 2 targets. The energy dependence of the cross sections is compared to theoretical predictions for atomic and molecular hydrogen targets. Both experiments were performed by measuring only the final charge state of the projectile. In the second section we describe the measurement of partial cross sections for the same collisions by measuring the target recoil charge state in coincidence with the projectile charge state. By this method we can measure pure single- and double-ionization of the target, pure single-electron transfer and transfer ionization, and pure double-electron transfer. This experiment is presently being performed for bare flourine on He; however, absolute cross sections are not available at the time of this conference. (orig.)

  4. Development of a liquid {sup 3}He target for experimental studies of antikaon-nucleon interaction at J-PARC

    Energy Technology Data Exchange (ETDEWEB)

    Iio, M., E-mail: masami.iio@kek.jp [RIKEN Nishina Center, RIKEN, Saitama 351-0198 (Japan); High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Ishimoto, S. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Sato, M. [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Enomoto, S. [Department of Physics, Osaka University, Osaka 560-0043 (Japan); Hashimoto, T. [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Suzuki, S. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Iwasaki, M. [RIKEN Nishina Center, RIKEN, Saitama 351-0198 (Japan); Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Hayano, R.S. [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan)

    2012-09-21

    A liquid {sup 3}He target system was developed for experimental studies of kaonic atoms and kaonic nuclei at J-PARC. {sup 3}He gas is liquefied in a heat exchanger cooled below 3.2 K by decompression of liquid {sup 4}He. To maintain a large acceptance of the cylindrical detector system for decay particles of kaonic nuclei, efficient heat transport between the separate target cell and the main unit is realized using circulation of liquid {sup 3}He. To minimize the amount of material, a vacuum vessel containing a carbon fiber reinforced plastic cylinder having an inside diameter of 150 mm and a thickness of 1 mm was produced. A target cell made of pure beryllium and beryllium-aluminum alloy was developed not only to minimize the amount of material but also to obtain high X-ray transmission. During a cooling test, the target cell was kept at 1.3 K at a pressure of 33 mbar. The total estimated heat load to the components including the target cell and heat exchanger cooled by liquid {sup 4}He decompression, was 0.21 W, and the liquid {sup 4}He consumption rate was 50 L/day.

  5. Prediction of (n, 3He) cross sections around 14 MeV

    International Nuclear Information System (INIS)

    Atasoy, H.; Doekmen, S.

    1995-01-01

    A comprehensive review of the neutron-induced cross-reactions for (n, 3 He) reactions has been made for the interval of 14 ≤ Z ≤ 84 around 14 MeV neutron energy. For practical purposes, an empirical expression has been found by using the experimental (n, 3 He) cross section values as a function of (N - Z) and (E n - E th ) where (N - Z) is the neutron excess of the target nucleus, E n and E th are the incident neutron energy and the (n, 3 He) threshold energy, respectively. The derived empirical relation gives a good fit with the experimental values

  6. Development of a {sup 3}He magnetometer for a neutron electric dipole moment experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kraft, Andreas; Heil, Werner; Lauer, Thorsten; Neumann, Daniel [Johannes Gutenberg University, Institute of Physics, Mainz (Germany); Koch, Hans-Christian [Johannes Gutenberg University, Institute of Physics, Mainz (Germany); University of Fribourg, Physics Department, Fribourg (Switzerland); Daum, Manfred [Paul Scherrer Institute, Villigen (Switzerland); Pazgalev, Anatoly [Ioffe Institute, St Petersburg (Russian Federation); Sobolev, Yuri [Johannes Gutenberg University, Institute of Nuclear Chemistry, Mainz (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Weis, Antoine [University of Fribourg, Physics Department, Fribourg (Switzerland)

    2014-01-01

    We have developed a highly sensitive {sup 3}He magnetometer for the accurate measurement of the magnetic field in an experiment searching for an electric dipole moment of the neutron. By measuring the Larmor frequency of nuclear spin polarized {sup 3}He atoms a sensitivity on the femto-Tesla scale can be achieved. A {sup 3}He/Cs-test facility was established at the Institute of Physics of the Johannes Gutenberg University in Mainz to investigate the readout of {sup 3}He free induction decay with a lamp-pumped Cs magnetometer. For this we designed and built an ultra-compact and transportable polarizer unit which polarizes {sup 3}He gas up to 55% by metastability exchange optical pumping. The polarized {sup 3}He was successfully transfered from the polarizer into a glass cell mounted in a magnetic shield and the {sup 3}He free induction decay was detected by a lamp-pumped Cs magnetometer. (orig.)

  7. The first-to-zero-sound transition in non-superfluid liquid 4He

    International Nuclear Information System (INIS)

    Woods, A.D.B.; Svensson, E.C.; Martel, P.

    1976-01-01

    Neutron inelastic scattering from 4 He at T=2.3 K shows that for Q -1 'sound-wave' excitations propagate with the characteristics of ordinary or first sound while for Q > approximately 3nm -1 they propagate with the characteristics of zero sound. (Auth.)

  8. {sup 3}He retention and structural evolution in erbium tritides: Phase and aging effects

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.S., E-mail: zlxs77@163.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Thin Film Centre, Scottish Universities Physics Alliance (SUPA), University of West of Scotland, Paisley PA1 2BE, Scotland (United Kingdom); Zhang, L.; Wang, W.D.; Liu, Q. [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Peng, S.M., E-mail: pengshuming@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Ding, W.; Long, X.G.; Cheng, G.J.; Liang, J.H. [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Fu, Y.Q. [Thin Film Centre, Scottish Universities Physics Alliance (SUPA), University of West of Scotland, Paisley PA1 2BE, Scotland (United Kingdom)

    2015-06-15

    Highlights: • Effects of phase changes on {sup 3}He retention of Er tritide films were investigated. • The α phase in Er tritide films had no apparent effect on {sup 3}He release/retention. • Tritium content in the β phase showed significant effects on {sup 3}He retention. • Evolution of {sup 3}He in the β phase was apparently influenced by the γ phase. • Effects of phase changes on structure evolution of Er tritides were investigated. - Abstract: Effects of phase changes on {sup 3}He release/retention and crystal lattice evolution during aging of erbium (Er) tritide films were investigated using X-ray diffraction. The contents of α phase and γ phase in the Er tritide films showed significant different effects on {sup 3}He release/retention. The initial tritium stoichiometry or excess tritium atoms accommodated in the octahedral sites and the microstructure (i.e., the texture and Er{sub 2}O{sub 3} oxide inclusions) played an important role for the {sup 3}He release and the evolution of {sup 3}He bubbles in the β phase Er tritide films. In the β + γ region, evolution of {sup 3}He in the β phase was apparently influenced by the γ phase, which could result in a strongly anisotropic lattice dilation and an earlier inflection point of the expansion rate of (1 1 1) lattice parameter. A preferred occupation of {sup 3}He in basal plane of the hexagonal γ phase and the lattice expansion along the hexagonal direction were identified.

  9. Polarized 3He Neutron Spin Filters

    Energy Technology Data Exchange (ETDEWEB)

    Sno, William Michael [Indiana Univ., Bloomington, IN (United States)

    2016-01-12

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

  10. Molecular treatment of He++H collisions

    International Nuclear Information System (INIS)

    Macias, A.; Riera, A.; Yanez, M.

    1981-01-01

    Total cross sections for the reactions 4 He + (1s)+H(1s)→ 4 He + (1s)+H(2p), 4 He + (1s) + H(1s)→ 4 He(1s2p /sup 1,3/P)+H + are calculated in an impact-parameter formalism, for collision energies 0.5--30 keV, using a molecular approach. The molecular energies are calculated at large internuclear distances by a configuration-interaction method, and at short distances by a block-diagonalization method. The radial couplings between the molecular wave functions are evaluated exactly, and turn out to depend strongly on the choice of origin of electronic coordinates; as a consequence, the cross sections also depend on this choice. The effect of the anomalous rotational couplings which decrease like R -1 is shown to be negligible, and a method to integrate them is proposed in the Appendix. Choosing the center of mass as origin of electronic coordinates, we obtain good agreement with experimental data, but we find no a priori reason to favor this choice. As an important conclusion, the main effect of the so-called momentum-transfer problem, which is the origin dependence of the cross sections, is due to the form of the molecular wave functions at short internuclear distances

  11. Inelastic neutron scattering from high-density fcc 4He

    International Nuclear Information System (INIS)

    Thomlinson, W.; Eckert, J.; Shirane, G.

    1978-01-01

    The phonon dispersion relations in high-density crystals of fcc 4 He have been measured along high-symmetry directions by the neutron-inelastic-scattering technique. A recent study of the lattice dynamics of fcc 4 He by Eckert et al. has been extended to cover the fcc phase diagram at pressures below 5 kbar. Molar volumes of 9.03, 9.43, and 9.97 cm 3 /mole have been studied in the temperature range from near the melting curve to near the fcc-hcp transition line. The phonon dispersion relations are in good agreement with a first-order self-consistent phonon theory calculation by Goldman. The observed phonon-group line shapes at large energy and momentum transfers show evidence for multiphonon scattering in agreement with calculations by Glyde. Eckert et al. reported extremely large anharmonic isochoric temperature shifts of the phonon energies. The present work studied the shifts as a function of molar volume and temperature. Mode-Grueneisen-parameter dispersion curves have been measured using the present data and earlier measurements at lower density in the fcc phase by Traylor et al. Macroscopic Grueneisen parameters have been calculated from the phonon density of states obtained from the data

  12. Electroproduction of the neutral pion off 4He

    Energy Technology Data Exchange (ETDEWEB)

    Torayev, Bayram [Old Dominion Univ., Norfolk, VA (United States)

    2016-12-01

    Deeply virtual exclusive processes offer a unique opportunity to study the internal structure of the nucleon and nuclei. The goal of this work is to extract the beam-spin asymmetry in deeply virtual coherent neutral pion electroproduction, e^4He to e'^4He'pi^0, using the CLAS detector in the experimental Hall B at Thomas Jefferson National Accelerator Facility. The data were collected in 2009 with a 6 GeV longitudinally polarized electron beam impinging on a 30 cm long, 6 atm Helium-4 gaseous target. In order to ensure that the process is coherent, a new Radial Time Projection Chamber was used to detect and identify low energy recoil a-particles. The Beam Spin Asymmetry in the coherent deep exclusive regime was measured at Q^2 = 1.50 GeV^2, xB = 0.18 and -t = 0.14 GeV^2. The measured asymmetry has an amplitude of 10%+/-5% and has the opposite sign compared the asymmetry measured for pi^0 production on the proton.

  13. Mechanisms of the p(He 6,He 5)d, p(He 6,α)t and p(He 6,t)α reactions

    International Nuclear Information System (INIS)

    Heiberg-Andersen, Henning

    2002-07-01

    This work was devoted to nucleon induced transfer reactions having the potential to probe the sub-cluster structures of the benchmark halo nucleus He 6, without the question marks the necessarily omitted exchange effects tend to put behind the CRC results when both collision partners are composite systems. Still, the exchange complications entered the analysis in an ironic way: The high Q-value of the p(He 6,α)t and p(He 6, t)α reactions caused sensitivity to the t - α optical potential at small radii, where the one-nucleon exchange effects are strongest. Since the attempt to throw them out of the extracted tau - α potential failed, it was necessary to extend the model space to avoid a too difficult modelling of the local equivalent t - α potential. By this step, all the complications originating from antisymmetrization within a larger model space entered the analysis. However, the persistent failures of the two-channel calculations of this and previous works can hardly be due to incorrect treatment of exchange effects only, so the loss of simplicity is probably illusory. Even at small angles, where the surface processes dominate, none of the two-channel calculations with various choices of t - α optical potentials managed to reproduce the p(He 6, α)t (p(He 6,t)α) data. This motivated inclusion of sequential transfers through the d + He 5 channel, where the sequential triton transfer process, included just for consistency in the coupling scheme of the four-channel calculation, turned out to be more influent than expected. The satisfactory reproduction of both the p(He 6, He 5)d and the p(He 6,α)t (p(He 6,t)α) data by the four-channel approach and the required re-normalization the real part of the p - He 6 optical potential are strong indications of substantial contributions from sequential transfer of the halo neutrons at this energy. The conclusions that can be drawn from this work are limited by the modest amount of available data. This limitation does

  14. Mechanisms of the p(He 6,He 5)d, p(He 6,{alpha})t and p(He 6,t){alpha} reactions

    Energy Technology Data Exchange (ETDEWEB)

    Heiberg-Andersen, Henning

    2002-07-01

    This work was devoted to nucleon induced transfer reactions having the potential to probe the sub-cluster structures of the benchmark halo nucleus He 6, without the question marks the necessarily omitted exchange effects tend to put behind the CRC results when both collision partners are composite systems. Still, the exchange complications entered the analysis in an ironic way: The high Q-value of the p(He 6,{alpha})t and p(He 6, t){alpha} reactions caused sensitivity to the t - {alpha} optical potential at small radii, where the one-nucleon exchange effects are strongest. Since the attempt to throw them out of the extracted tau - {alpha} potential failed, it was necessary to extend the model space to avoid a too difficult modelling of the local equivalent t - {alpha} potential. By this step, all the complications originating from antisymmetrization within a larger model space entered the analysis. However, the persistent failures of the two-channel calculations of this and previous works can hardly be due to incorrect treatment of exchange effects only, so the loss of simplicity is probably illusory. Even at small angles, where the surface processes dominate, none of the two-channel calculations with various choices of t - {alpha} optical potentials managed to reproduce the p(He 6, {alpha})t (p(He 6,t){alpha}) data. This motivated inclusion of sequential transfers through the d + He 5 channel, where the sequential triton transfer process, included just for consistency in the coupling scheme of the four-channel calculation, turned out to be more influent than expected. The satisfactory reproduction of both the p(He 6, He 5)d and the p(He 6,{alpha})t (p(He 6,t){alpha}) data by the four-channel approach and the required re-normalization the real part of the p - He 6 optical potential are strong indications of substantial contributions from sequential transfer of the halo neutrons at this energy. The conclusions that can be drawn from this work are limited by the

  15. sup 8 He- sup 6 He a comparative study of electromagnetic fragmentation reactions

    CERN Document Server

    Meister, M; Aleksandrov, D.; Aumann, T.; Baumann, T.; Borge, M.J.G.; Chulkov, L.V.; Cortina-Gil, D.; Eberlein, B.; Elze, Th.W.; Emling, H.; Geissel, H.; Hellström, M.; Jonson, B.; Kratz, J.V.; Kulessa, R.; Leistenschneider, A.; Mukha, I.; Münzenberg, G.; Nickel, F.; Nilsson, T.; Nyman, G.; Pfützner, M.; Pribora, V.; Richter, A.; Riisager, K.; Scheidenberger, C.; Schrieder, G.; Simon, H.; Tengblad, O.; Zhukov, M.V.

    2002-01-01

    Dissociation of a 227 MeV/u sup 8 He beam in a lead target has been studied in a kinematically complete experiment. The results are compared with similar data from the well-known halo nucleus sup 6 He. Coulomb-nuclear interference in the inelastic channel gives evidence for a I suppi=1 sup - resonance in sup 8 He at E sub x =4.15 MeV. The deduced B(E1) value of 0.38+-0.07 e sup 2 fm sup 2 indicates a uniform distribution of the four neutrons around the alpha-particle core.

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

    International Nuclear Information System (INIS)

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

    2006-01-01

    Low-mass stars, ∼ 1-2 solar masses, near the Main Sequence are efficient at producing 3 He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3 He with the predictions of both stellar and Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus we are able to remove the threat that 3 He production in low-mass stars poses to the Big Bang nucleosynthesis of 3 He

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

    Science.gov (United States)

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

    2006-12-08

    Low-mass stars, approximately 1 to 2 solar masses, near the Main Sequence are efficient at producing the helium isotope 3He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3He with the predictions of both stellar and Big Bang nucleosynthesis. Here we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus, we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He.

  18. Spinning superfluid 4He nanodroplets

    Science.gov (United States)

    Ancilotto, Francesco; Barranco, Manuel; Pi, Martí

    2018-05-01

    We have studied spinning superfluid 4He nanodroplets at zero temperature using density functional theory. Due to the irrotational character of the superfluid flow, the shapes of the spinning nanodroplets are very different from those of a viscous normal fluid drop in steady rotation. We show that when vortices are nucleated inside the superfluid droplets, their morphology, which evolves from axisymmetric oblate to triaxial prolate to two-lobed shapes, is in good agreement with experiments. The presence of vortex arrays confers to the superfluid droplets the rigid-body behavior of a normal fluid in steady rotation, and this is the ultimate reason for the surprising good agreement between recent experiments and the classical models used for their description.

  19. Improved fission neutron energy discrimination with {sup 4}He detectors through pulse filtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ting, E-mail: ting.zhu@ufl.edu [University of Florida, Gainesville, FL (United States); Liang, Yinong; Rolison, Lucas; Barker, Cathleen; Lewis, Jason; Gokhale, Sasmit [University of Florida, Gainesville, FL (United States); Chandra, Rico [Arktis Radiation Detectors Ltd., Räffelstrasse 11, Zürich (Switzerland); Kiff, Scott [Sandia National Laboratories, CA (United States); Chung, Heejun [Korean Institute for Nuclear Nonproliferation and Control, 1534 Yuseong-daero, Yuseong-gu, Daejeon (Korea, Republic of); Ray, Heather; Baciak, James E.; Enqvist, Andreas; Jordan, Kelly A. [University of Florida, Gainesville, FL (United States)

    2017-03-11

    This paper presents experimental and computational techniques implemented for {sup 4}He gas scintillation detectors for induced fission neutron detection. Fission neutrons are produced when natural uranium samples are actively interrogated by 2.45 MeV deuterium-deuterium fusion reaction neutrons. Fission neutrons of energies greater than 2.45 MeV can be distinguished by their different scintillation pulse height spectra since {sup 4}He detectors retain incident fast neutron energy information. To enable the preferential detection of fast neutrons up to 10 MeV and suppress low-energy event counts, the detector photomultiplier gain is lowered and trigger threshold is increased. Pile-up and other unreliable events due to the interrogating neutron flux and background radiation are filtered out prior to the evaluation of pulse height spectra. With these problem-specific calibrations and data processing, the {sup 4}He detector's accuracy at discriminating fission neutrons up to 10 MeV is improved and verified with {sup 252}Cf spontaneous fission neutrons. Given the {sup 4}He detector's ability to differentiate fast neutron sources, this proof-of-concept active-interrogation measurement demonstrates the potential of special nuclear materials detection using a {sup 4}He fast neutron detection system.

  20. Safety in the ARIES-III D-3He tokamak reactor design

    International Nuclear Information System (INIS)

    Herring, J.S.; Dolan, T.J.

    1992-01-01

    This paper reports on the ARIES-III reactor study, an extensive examination of the viability of a D- 3 He-fueled commercial tokamak powder reactor. Because neutrons are produced only through side reactions (D+D- 3 HE+N; and D+D-T+p followed by D+T- 4 He+n), the reactor has the significant advantages of reduced activation of the first wall and shield, low afterheat and Class A or C low level waste disposal. Since no tritium is required for operation, no lithium-containing breeding blanket is necessary. A ferritic steel shield behind the first wall protects the magnets from gamma and neutron heating and from radiation damage. The authors explored the potential for isotopically tailoring the 4 mm tungsten layer on the divertor in order to reduce the offsite doses should a tungsten aerosol be released from the reactor after an accident. The authors also modeled a loss-of-cooling accident (LOCA) in which the organic coolant was burning in order to estimate the amount of radionuclides released from the first wall. Because the maximum temperature is low, degree C, release fractions are small. The authors analyzed the disposition of the 20 g/day of tritium that is produced by D-D reactions and removed by the vacuum pumps

  1. First doubly polarised photoproduction on {sup 3}He at the photon beam of MAMI

    Energy Technology Data Exchange (ETDEWEB)

    Aguar Bartolome, Patricia

    2010-11-15

    A first experiment with a polarised {sup 3}He target was carried out in July 2009 at the MAMI accelerator in Mainz in a photon energy range between 200 MeV and 800 MeV. The aim of this measurement was to investigate the Gerasimov-Drell-Hearn sum rule on the neutron. The use of the data obtained with the polarised {sup 3}He target, compared to existing data on the deuteron, gives a complementary and more direct access to the neutron, due to the spin structure of the {sup 3}He. The measurement of the helicity dependence of the inclusive total photoabsorption cross section required a beam of tagged circularly polarised photons incident on the longitudinally polarised {sup 3}He target. The data were taken using the 4{pi} Crystal Ball photon spectrometer in combination with TAPS as a forward wall and complemented by a threshold Cherenkov detector used to on-line suppress the background from electromagnetic events. The development and preparation of the different components of the {sup 3}He experimental setup was an important part of this work and are described in detail in this thesis. The detector system and the analysis method were tested by the measurement of the unpolarised total inclusive photoabsorption cross section on liquid hydrogen. The results obtained are in good agreement with previous published data. Preliminary results of the unpolarised total photoabsorption cross section, as well as the helicity dependent photoabsorption cross section difference on {sup 3}He compared with several theoretical models will also be presented. (orig.)

  2. Removing gaseous contaminants in 3He by cryogenic stripping

    International Nuclear Information System (INIS)

    Benapfl, M.; Biltoft, P.; Coombs, A.

    1995-01-01

    The Tritium Operations Group at LLNL, Tritium Facility has recently developed a 3 He recovery system to remove argon, xenon, neon, hydrogen, and all other contaminants from the 3 He stream in an Accelerator Production of Tritium (APT) experimental apparatus. In this paper the authors will describe in detail the background information, technical requirements, the design approach, and the results of their experimental tests. The authors believe this gas purification system may have other applications as it provides at a reasonable cost an efficient method for purification of gaseous helium

  3. Bose condensation in 4He and neutron scattering

    International Nuclear Information System (INIS)

    Silver, R.N.

    1997-01-01

    The discovery of superfluidity in liquid 4 He below T λ = 2.17 K, and its phenomenological characterization since then, has been one of the great success stories of condensed matter physics. The relation of superfluidity to the behavior of atoms was conjectured by F. London in 1938. Superfluidity is a manifestation of the Bose condensation of helium atoms, the extensive occupation of the zero momentum state. Ever since 4 He has been the paradigm in the search for Bose condensates in other systems. At the Pune meeting scientists have heard exciting new evidence for Bose condensates of laser cooled alkali atoms in magnetic traps, of excitons in Cu 2 O, and possibly pre-formed Cooper pairs of electrons in the high T c perovskite superconductors. There remains the holy-grail of forming a Bose condensate in spin-polarized hydrogen. In the current excitement for new types of Bose condensates, and new phenomena such as atom lasers, it may be useful to recall the older story of the experimental verification of a relation between superfluidity and Bose condensation in 4 He. This topic has been investigated over many years by neutron scattering experiments and quantum many-body theory. The authors goal is to illustrate the difficulties of establishing the existence of a Bose condensate in a strongly interacting system, even though its macroscopic effects are manifest. The author assumes readers have access to a review by Silver and Sokol which emphasizes the neutron scattering theory through 1990 and a review by Snow and Sokol of the deep inelastic neutron scattering (DINS) experiments through 1995

  4. Autoionization spectra of He excited by fast (MeV) H/sup +/, He/sup +/, and Li/sup n//sup +/ (N = 1,2,3) ions

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, D.; Arcuni, P.; Bruch, P.; Stoeffler, W.

    1983-01-01

    Autoionization spectra of He following excitation by 1 to 3 MeV H/sup +/, He/sup +/, and Li/sup n//sup +/ (n = 1,2,3) have been measured as a function of observation angle. The (2p/sup 2/)/sup 1/D and (2s2p)/sup 1/P resonances have been examined and a strong dependence on projectile velocities, charge state and observation angle was found. The measurements were performed in a crossed-beam scattering chamber. The target-gas pressure was in the order of 10/sup -4/ Torr. The secondary electrons have been energy analyzed by a 45/sup 0/ parallel-plate analyzer. Results are presented and discussed. (WHK)

  5. The πHe3H3 coupling constant estimation using the Chew-Low equation

    International Nuclear Information System (INIS)

    Mach, R.; Nichitiu, F.

    1976-01-01

    A semi-phenomenological analysis of the π +- He 3 elastic scattering at 98, 120, 135 and 156 Mev is presented. An information of the πHe 3 H 3 coupling constant using the Chew-Low plot for the P 33 partial wave is obtained. (author)

  6. The πHe3H3 coupling constant estimation using the Chew-Low equation

    International Nuclear Information System (INIS)

    Mach, R.; Nichitiu, F.

    1975-01-01

    In this paper it is presented an estimation of the πHe 3 H 3 coupling constant using the Chew-Low equation and a semi-phenomenological analysis of the π -+ He 3 elastic differential cross sections at 98, 120, 135 and 156 MeV

  7. Finite size effects in the evaporation rate of 3He clusters

    International Nuclear Information System (INIS)

    Guirao, A.; Pi, M.; Barranco, M.

    1991-01-01

    We have computed the density of states and the evaporation rate of 3 He clusters, paying special attention to finite size effects which modify the 3 He level density parameter and chemical potential from their bulk values. Ready-to-use liquid-drop expansions of these quantities are given. (orig.)

  8. Rotational spectrum of the NH3He van der Waals complex

    Directory of Open Access Journals (Sweden)

    Surin L.

    2017-01-01

    Full Text Available The interaction between ammonia and helium has attracted considerable interest over many years, partly because of the observation of interstellar ammonia. The rate coefficients of NH3He scattering are an important ingredient for numerical modeling of astrochemical environments. Another, though quite different application in which the NH3He interaction can play an important role is the doping of helium clusters with NH3 molecules to perform high-resolution spectroscopy. Such experiments are directed on the detection of non-classical response of molecular rotation in helium clusters addressing fundamental questions related to the microscopic nature of superfluidity. High-resolution spectroscopy on the NH3He complex is an important tool for increasing our understanding of intermolecular forces between NH3 and He.

  9. The π+-emission puzzle in 4 over Lambda He decay

    International Nuclear Information System (INIS)

    Gibson, B.F.; Timmermans, R.

    1997-10-01

    The observed π + emission from the weak decay of 4 over Λ He has long been an intriguing puzzle. Experimentally, the π + to π - ratio for 4 over Λ He decay is about 5%. Because mesonic decay modes of the free Λ (→ p + π - , n + π 0 ) produce no π + s, more complicated mechanisms must be responsible for the π + decay of 4 over Λ He. Dalitz and von Hippel explored two-body decay processes of the type: (1) Λ → π 0 + n decay followed by a π 0 + p → π + + n charge-exchange reaction, and (2) Σ + → π + + n decay following a Λ + p → Σ + + n conversion. They concluded that neither process could account for even a 1% π + + n decay as a p-wave process ruled out the promising explanation coming from von Hippel's calculations, which had found that s-wave Σ + decay might yield a sufficiently high rate. Cieply and Gal re-examined the charge-exchange contribution and concluded that, although up-to-date input parameters yield a 1.2% branching ratio, the charge-exchange mechanism cannot account for the experimental value of about 5%

  10. Ratio of He{sup 2+}/He{sup +} from 80 to 800 eV

    Energy Technology Data Exchange (ETDEWEB)

    Samson, J.A.R.; Stolte, W.C.; He, Z.X. [Univ. of Nebraska, Lincoln, NE (United States)] [and others

    1997-04-01

    The importance of studying the double ionization of He by single photons lies in the fact that He presents the simplest structure for the study of electron correlation processes. Even so it has proved a challenging problem to understand and describe theoretically. Surprisingly, it has also proved difficult to agree experimentally on the absolute values of the He{sup 2+}/He{sup +} ratios. The availability of new synchrotron facilities with high intensity light outputs have increased the experimental activity in this area. However, by the very nature of those continuum sources systematic errors occur due to the presence of higher order spectra and great care must be exercised. The authors have measured the He{sup 2+}/He{sup +} ratios over a period of 5 years, the last three at the ALS utilizing beamlines 9.0.1 and 6.3.2. The sources of systematic errors that they have considered include: scattered light, higher order spectra, detector sensitivity to differently charged ions, discriminator levels in the counting equipment, gas purity, and stray electrons from filters and metal supports. The measurements have been made at three different synchrotron facilities with different types of monochromators and their potential for different sources of systematic errors. However, the authors data from all these different measurements agree within a few percent of each other. From the above results and their precision total photoionization cross sections for He, the authors can obtain the absolute photoionization cross section for He{sup 2+}. They find similar near perfect agreement with several of the latest calculations.

  11. Capillary Condensation of Liquid 4He in Aerogel on Cooling Through λ Point

    International Nuclear Information System (INIS)

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

    2006-01-01

    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 λ 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

  12. Analysis for In-situ Fission Rate Measurements using 4He Gas Scintillation Detectors

    International Nuclear Information System (INIS)

    Lewis, Jason M.; Raetz, Dominik; Jordan, Kelly A.; Murer, David

    2013-06-01

    Active neutron interrogation is a powerful NDA technique that relies on detecting and analyzing fission neutrons produced in a fuel sample by an interrogating high neutron flux. 4 He scintillation gas fast neutron detectors are investigated in this paper for use in a novel fission rate measurement technique The He-4 detectors have excellent gamma rejection, a fast response time, and give significant information on incident neutron energy allowing for energy cuts to be applied to the detected signal. These features are shown in this work to allow for the detection of prompt fission neutrons in-situ during active neutron interrogation of a 238 U sample. The energy spectrum from three different neutrons sources ( 252 Cf, AmBe, AmLi) is measured using the 4 He detection system and analyzed. An initial response matrix for the detector is determined using these measurements and the kinematic interaction properties of the elastic scattering with the 4 He. (authors)

  13. A compact copper nuclear demagnetization cryostat and a search for superfluidity in solid 4He

    International Nuclear Information System (INIS)

    Haar, P.G. van de.

    1991-01-01

    The subject of this thesis is the theoretical and experimental study of matter at low temperatures, and the development of techniques to reach and measure these temperatures. A copper nuclear demagnetization cryostat was developed in order to reach low temperatures. This system distinguishes itself from other cryostats by its compact construction. The lowest temperature recorded by a pulsed Pt-NMR thermometer was 115 μK. This system was used to search for superfluidity in solid 4 He. Due to the large zero-point motion of the atoms, 4He remains liquid down to zero temperature; a pressure of 25.3 bar is needed to force the atoms in a lattice. Even in solid state, the 4 He atoms remain very mobile, changing lattice sites at a frequency of approximately 10 7 Hz. It is possible that solid 4 He contains vacancies at zero temperature. These zero point vacancies are expected to behave like a gas of bosons, and should Bose-condense at some temperature. From experiments the upper limit to the vacancy concentration is set of 4·10-5. (author). 217 refs.; 46 figs.; 2 tabs

  14. Precision Measurement of the Rovibrational Energy-Level Structure of ^{4}He^{+}_{2}

    Science.gov (United States)

    Semeria, Luca; Jansen, Paul; Agner, Josef A.; Schmutz, Hansjürg; Merkt, Frederic

    2017-06-01

    He_{2}^{+} is a three-electron system for which highly accurate ab initio calculations are possible. The latest calculations of the rovibrational energies of He_{2}^{+} by Tung et al. have a reported accuracy of 120 MHz, although they do not include relativistic and quantum electrodynamics (QED) effects. We determined the rovibrational structure of ^{4}He^{+}_{2} from measurements of the Rydberg spectrum of metastable a ^3Σ_u^+ He_{2} (He^{*}_{2} hereafter) and Rydberg-series extrapolation using multichannel quantum-defect-theory. He^{*}_{2} molecules are produced in supersonic beams with velocities tunable down to about 100 m/s by combining a cryogenic supersonic-beam source with a multistage Zeeman decelerator. They are then excited to high-np Rydberg states by single-photon excitation. In the experiments, we use a pulsed uv laser system, with a near Fourier-transform-limited bandwidth of 150 MHz. The Zeeman deceleration reduces the systematic uncertainty arising from a possible Doppler shift and greatly simplifies the spectral assignment because of its spin-rotational state selectivity. Results will be presented on the rotational structure of the lowest three vibrational levels of He^{+}_{2}. The unprecedented accuracy that we have obtained for the v^{+}=0 rotational intervals of He_{2}^{+} enables the quantification of the relativistic and QED corrections by comparison with the results of Tung et al.^a W.-C. Tung, M. Pavanello and L. Adamowicz, J. Chem. Phys., 136, 104309, 2012. C. Jungen, Elements of Quantum Defect Theory, in : Handbook of High-resolution Spectroscopy, 2001. D. Sprecher, J. Liu, T. Krähenmann, M. Schäfer, and F. Merkt, J. Chem. Phys., 140, 064304, 2014. A. W. Wiederkehr, S. D. Hogan, M. Andrist, H. Schmutz, B. Lambillotte, J. A. Agner, and F. Merkt., J. Chem. Phys., 135, 214202, 2011. M. Motsch, P. Jansen, J. A. Agner, H. Schmutz, and F. Merkt, Phys. Rev. A, 89, 043420, 2014. P. Jansen, L. Semeria, L. E. Hofer, S. Scheidegger, J. A. Agner

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

    Science.gov (United States)

    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

  16. Interaction of Ne(2p54p), Ar(3p54p) and Kr(4p55p) excited atoms with He and Ne atoms. Processes of collisional depolarization

    International Nuclear Information System (INIS)

    Zagrebin, A.L.; Lednev, M.G.

    1990-01-01

    Quasimolecular terms Ne(2p 5 4p)+He, Ar(3p 5 4p)+He,Ne and Kr(4p 5 5p)+He,Ne are calculated within the framework of one-configuration method of effective Hamiltonian. The results of calculations agree with the experimental data

  17. Quantum Monte Carlo and the equation of state of liquid 3He

    International Nuclear Information System (INIS)

    Panoff, R.M.

    1987-01-01

    The author briefly reviews the present status of Monte Carlo technology as it applies to the study of the ground-state properties of strongly-interacting many-fermion systems in general, and to liquid 3 He at zero temperature in particular. Variational Monte Carlo methods are reviewed and the model many-body problem to be tackled is introduced. He outlines the domain Green's function Monte Carlo method with mirror potentials providing a coherent framework for discussing solutions to the fermion problem. He presents results for the zero-temperature equation of state of 3 He, along with other ground-state properties derived from the many-body wave function

  18. The electrodisintegration of 3He studied with the 3He(e,e'p)2H and 3He(e,e'd)1H reactions

    International Nuclear Information System (INIS)

    Keizer, P.H.M.

    1986-01-01

    The author presents a survey of experimental and theoretical results for the ground-state properties of 3 He. The formalism of the (e,e'p) and (e,e'd) reactions is presented. A short description of the instrumentation, in particular those elements which are typical for the present study, and of the data analysis is given. This includes a description of the elements required in the 'recoil detection' technique. The kinematics of the experiments and the results are presented. The results are discussed and compared with calculations. (Auth.)

  19. Hyperpolarized 3He magnetic resonance imaging: Preliminary evaluation of phenotyping potential in chronic obstructive pulmonary disease

    International Nuclear Information System (INIS)

    Mathew, Lindsay; Kirby, Miranda; Etemad-Rezai, Roya; Wheatley, Andrew; McCormack, David G.; Parraga, Grace

    2011-01-01

    Rationale and objectives: Emphysema and small airway obstruction are the pathological hallmarks of chronic obstructive pulmonary disease (COPD). The aim of this pilot study in a small group of chronic obstructive pulmonary disease (COPD) patients was to quantify hyperpolarized helium-3 ( 3 He) magnetic resonance imaging (MRI) functional and structural measurements and to explore the potential role for 3 He MRI in detecting the lung structural and functional COPD phenotypes. Materials and methods: We evaluated 20 ex-smokers with stage I (n = 1), stage II (n = 9) and stage III COPD (n = 10). All subjects underwent same-day plethysmography, spirometry, 1 H MRI and hyperpolarized 3 He MRI at 3.0 T. 3 He ventilation defect percent (VDP) was generated from 3 He static ventilation images and 1 H thoracic images and the 3 He apparent diffusion coefficient (ADC) was derived from diffusion-weighted MRI. Results: Based on the relative contribution of normalized ADC and VDP, there was evidence of a predominant 3 He MRI measurement in seven patients (n = 3 mainly ventilation defects or VDP dominant (VD), n = 4 mainly increased ADC or ADC dominant (AD)). Analysis of variance (ANOVA) showed significantly lower ADC for subjects with predominantly elevated VDP (p = 0.02 compared to subjects with predominantly elevated ADC; p = 0.008 compared to mixed group) and significantly decreased VDP for subjects with predominantly elevated ADC (p = 0.003, compared to mixed group). Conclusion: In this small pilot study, a preliminary analysis shows the potential for 3 He MRI to categorize or phenotype COPD ex-smokers, providing good evidence of feasibility for larger prospective studies.

  20. EVIDENCE FOR ENHANCED {sup 3}HE IN FLARE-ACCELERATED PARTICLES BASED ON NEW CALCULATIONS OF THE GAMMA-RAY LINE SPECTRUM

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, R. J. [Code 7650, Naval Research Laboratory, Washington, DC 20375 (United States); Kozlovsky, B. [Tel Aviv University, Tel Aviv (Israel); Share, G. H., E-mail: murphy@ssd5.nrl.navy.mil, E-mail: benz@wise.tau.ac.il, E-mail: share@astro.umd.edu [University of Maryland, College Park, MD 20742 (United States)

    2016-12-20

    The {sup 3}He abundance in impulsive solar energetic particle (SEP) events is enhanced up to several orders of magnitude compared to its photospheric value of [{sup 3}He]/[{sup 4}He] = 1–3 × 10{sup −4}. Interplanetary magnetic field and timing observations suggest that these events are related to solar flares. Observations of {sup 3}He in flare-accelerated ions would clarify the relationship between these two phenomena. Energetic {sup 3}He interactions in the solar atmosphere produce gamma-ray nuclear-deexcitation lines, both lines that are also produced by protons and α particles and lines that are essentially unique to {sup 3}He. Gamma-ray spectroscopy can, therefore, reveal enhanced levels of accelerated {sup 3}He. In this paper, we identify all significant deexcitation lines produced by {sup 3}He interactions in the solar atmosphere. We evaluate their production cross sections and incorporate them into our nuclear deexcitation-line code. We find that enhanced {sup 3}He can affect the entire gamma-ray spectrum. We identify gamma-ray line features for which the yield ratios depend dramatically on the {sup 3}He abundance. We determine the accelerated {sup 3}He/ α ratio by comparing these ratios with flux ratios measured previously from the gamma-ray spectrum obtained by summing the 19 strongest flares observed with the Solar Maximum Mission Gamma-Ray Spectrometer. All six flux ratios investigated show enhanced {sup 3}He, confirming earlier suggestions. The {sup 3}He/ α weighted mean of these new measurements ranges from 0.05 to 0.3 (depending on the assumed accelerated α /proton ratio) and has a <1 × 10{sup −3} probability of being consistent with the photospheric value. With the improved code, we can now exploit the full potential of gamma-ray spectroscopy to establish the relationship between flare-accelerated ions and {sup 3}He-rich SEPs.

  1. Proton-4He elastic scattering at intermediate energies

    International Nuclear Information System (INIS)

    Auger, J.P.; Gillespie, J.; Lombard, R.J.

    1975-12-01

    Differential elastic cross sections and polarizations are calculated in a multiple scattering formalism for proton- 4 He scattering for energies in the range 0.6-24GeV and for momentum transfers up to 4.0fmsup(-1). The calculations include Coulomb and spin effects. Corrections due to target-nucleon overlap and charge exchange are estimated. The results are compared with experimental data [fr

  2. Spin structure of the 3He from the dd → 3Hen reaction

    International Nuclear Information System (INIS)

    Ladygin, V.P.; Ladygina, N.B.

    1995-01-01

    The polarization observables in the reaction dd → 3 Hen are considered. Their high sensitivity to the 3 He wave function at short distances is shown. Using of both polarized target and beam allows to extend sufficiently the number of possible experiments and to separate 3 He structure from the reaction mechanisms using different relative orientations of initial deuteron spins. 27 refs., 5 figs

  3. Equality of analyzing power and polarization in the reaction 3H(p,n)3He

    International Nuclear Information System (INIS)

    Donoghue, T.R.; Doyle, S.M.A.; Clark, H.W.; Dries, L.J.; Regner, J.L.; Tornow, W.; Byrd, R.C.; Lisowski, P.W.; Walter, R.L.

    1976-01-01

    The quantities A/sub y/ and P/sub y/ were remeasured for E/sub p/ 3 H(p,n) 3 He. Although our A/sub y/ data confirm previous data, our P/sub y/ values are appreciably larger than earlier results and in fact agree well with those for A/sub y/. Elimination of the previously reported A/sub y/-P/sub y/ difference has important consequences. Charge-symmetry-breaking effects must be small or nonexistent in this reaction; and the previously required f-wave admixture to the lowest J/sup pi/=2 - state of 4 He is no longer necessary

  4. Brueckner Rearrangement Effects in $^5_\\Lambda$He and $^6_{\\Lambda\\Lambda}$He

    OpenAIRE

    Kohno, M.; Fujiwara, Y.; Akaishi, Y.

    2003-01-01

    Rearrangement effects in light hypernuclei are investigated in the framework of the Brueckner theory. We can estimate without detailed numerical calculations that the energy of the $\\alpha$-core is reduced by more than 2.5 MeV when the $\\Lambda$ adheres to $^4$He to form $^5_\\Lambda$He. Similar assessment of rearrangement contributions is essential to deduce the strength of $\\Lambda\\Lambda$ interaction from experimentally observed $\\Delta B_{\\Lambda\\Lambda}$. The recently observed experimenta...

  5. Charge Transfer Processes in Collisions of Si4+ Ions with He Atoms at Intermediate Energies

    Science.gov (United States)

    Suzuki, R.; Watanabe, A.; Sato, H.; Gu, J. P.; Hirsch, G.; Buenker, R. J.; Kimura, M.; Stancil, P. C.

    Charge transfer in collisions of Si4+ ions with He atoms below 100 keV/u is studied by using a molecular orbital representation within both the semiclassical and quantal representations. Single transfer reaction Si4++He →Si3++He+ has been studied by a number of theoretical investigations. In addition to the reaction (1), the first semiclassical MOCC calculations are performed for the double transfer channel Si4++HE→Si2++He2+ Nine molecular states that connect both with single and double electron transfer processes are considered in the present model. Electronic states and corresponding couplings are determined by the multireference single- and double- excitation configuration interaction method. The present cross sections tie well with the earlier calculations of Stancil et al., Phys. Rev. A 55, 1064 (1997) at lower energies, but show a rather different magnitude from those of Bacchus-Montabonel and Ceyzeriat, Phys. Rev. A 58, 1162 (1998). The present rate constant is found to be significantly different from the experimental finding of Fang and Kwong, Phys. Rev. A 59, 342 (1996) at 4,600 K, and hence does not support the experiment.

  6. Duoplasmatron source modifications for 3He+ operation

    Science.gov (United States)

    Schmidt, C. W.; Popovic, M.

    1998-02-01

    A duoplasmatron ion source is used to produce 25 mA of 3He+ with a pulse width of ˜80 ms at 360 Hz for acceleration to 10.5 MeV. At this energy, 3He striking water or carbon targets can produce short lived isotopes of 11C, 13N, 15O, and 18F for medical positron emission tomography (PET). A duoplasmatron ion source was chosen originally since it is capable of a sufficient singly charged helium beam with an acceptable gas consumption. Stable long-term operation of the source required a change in the filament material to molybdenum, and a careful understanding of the oxide filament conditioning, operation and geometry. Other improvements, particularly in the electronics, were helpful to increasing the reliability. The source has operated for many months at ˜2.5% duty factor without significant problems and with good stability. We report here the effort that was done to make this source understandable and reliable.

  7. Duoplasmatron source modifications for 3He+ Operation

    International Nuclear Information System (INIS)

    Schmidt, C.W.; Popovic, M.

    1997-11-01

    A duoplasmatron ion source is used to produce 25 mA of 3 He+ with a pulse width of ∼80 ms at 360 Hz for acceleration to 10.5 MeV. At this energy, 3 He striking water or carbon targets can produce short lived isotopes of 11 C, 13 N, 15 O and 18 F for medical positron emission tomography (PET). A duoplasmatron ion source was chosen originally since it is capable of a sufficient singly-charged helium beam with an acceptable gas consumption. Stable long-term operation of the source required a change in the filament material to molybdenum, and a careful understanding of the oxide filament conditioning, operation and geometry. Other improvements, particularly in the electronics, were helpful to increasing the reliability. The source has operated for many months at ∼2.5% duty factor without significant problems and with good stability. We report here the effort that was done to make this source understandable and reliable

  8. Duoplasmatron source modifications for 3He+ operation

    International Nuclear Information System (INIS)

    Schmidt, C.W.; Popovic, M.

    1998-01-01

    A duoplasmatron ion source is used to produce 25 mA of 3 He + with a pulse width of ∼80ms at 360 Hz for acceleration to 10.5 MeV. At this energy, 3 He striking water or carbon targets can produce short lived isotopes of 11 C, 13 N, 15 O, and 18 F for medical positron emission tomography (PET). A duoplasmatron ion source was chosen originally since it is capable of a sufficient singly charged helium beam with an acceptable gas consumption. Stable long-term operation of the source required a change in the filament material to molybdenum, and a careful understanding of the oxide filament conditioning, operation and geometry. Other improvements, particularly in the electronics, were helpful to increasing the reliability. The source has operated for many months at ∼2.5% duty factor without significant problems and with good stability. We report here the effort that was done to make this source understandable and reliable

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

    Science.gov (United States)

    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.

  10. Effect of plastic deformation and impurities on internal friction in solid He4

    International Nuclear Information System (INIS)

    Tsymbalenko, V.L.; AN SSSR, Chernogolovka. Inst. Fiziki Tverdogo Tela)

    1979-01-01

    The internal friction in solid He 4 samples of 20.55 cm 3 molar volume is measured at frequencies of 15 and 78 kHz. The samples are grown under constant pressure and also by the blocked capillary technique. The construction of the container was such that the damping on plastic deformation of solid helium could be measured. Internal friction is also investigated in solid helium samples containing admixtures of He 3 (from 0.01 to 0.1 at.%). A number of dislocation parameters could be determined on basis of the temperature and amplitude dependences of the damping predicted by the Granato-Lucke theory

  11. Real squashing mode in textures in 3He-B

    International Nuclear Information System (INIS)

    Mineev, V.P.

    1985-01-01

    The shape of the absorption line of ultrasound due to various components of the real squashing mode in textures in 3 He-B is investigated. An explanation is presented of the additional splitting of the absorption line for the M=0 component of the real squashing model in a magnetic field and of the absence of such splitting of lines with M=+-1, +-2 in the case of place geometry. The peculiarities of the shape of the ultrasound absorption lines for various components of the real squashing mode in a rotating cylindrical vessel with 3 He-B are discussed

  12. Research and design of 3He pressure control loop

    International Nuclear Information System (INIS)

    Huang Xin; Zhang Peisheng; Tang Guoliang; Zhang Aimin; Zhang Yingchao

    2008-01-01

    In order to carry out power transient tests for PWR fuel element in China Advanced Research Reactor (CARR), the research and conceptual design of 3He pressure control loop were completed. The working principle, design parameters and technological flow of the loop were described. It is seen that the a He loop can adjust the power of the tested PWR fuel element rapidly, evenly and flexibly and it is an optimal path to realize the power transient regulation for tested PWR fuel. (authors)

  13. Spin-isospin excitation of 3He with three-proton final state

    Science.gov (United States)

    Ishikawa, Souichi

    2018-01-01

    Spin-isospin excitation of the {}^3He nucleus by a proton-induced charge exchange reaction, {}^3He(p,n)ppp, at forward neutron scattering angle is studied in a plane wave impulse approximation (PWIA). In PWIA, cross sections of the reaction are written in terms of proton-neutron scattering amplitudes and response functions of the transition from {}3He to the three-proton state by spin-isospin transition operators. The response functions are calculated with realistic nucleon-nucleon potential models using a Faddeev three-body method. Calculated cross sections agree with available experimental data in substance. Possible effects arising from the uncertainty of proton-neutron amplitudes and three-nucleon interactions in the three-proton system are examined.

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

    Science.gov (United States)

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

    2014-05-01

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

  15. High-intensity, thin-target He-jet production source

    International Nuclear Information System (INIS)

    Bai, Y.; Vieira, D.J.; Wouters, J.M.; Butler, G.W.; Rosenauer, Dk; Loebner, K.E.G.; Lind, V.G.; Phillips, D.R.

    1996-01-01

    A thin-target He-jet system suited to the production and rapid transport of non-volatile radioactive species has been successfully operated with proton beam intensities of up to 700 μA. The system consists of a water-cooled, thin-target chamber, capillary gas transport system, moving tape/Ge detection system, and an aerosol generator/gas recirculator. The yields for a wide variety of uranium fission and deep spallation products have been measured and robust operation of the system demonstrated for several weeks. He-jet transport and collection efficiencies ranged between 15 and 25% with collection rates of 10 7 to 10 8 atoms/sec/isotope. The high-intensity, thin-target He-jet approach represents a robust production source for nonvolatile radioactive heavy ion beams

  16. 4-D segmentation and normalization of 3He MR images for intrasubject assessment of ventilated lung volumes

    Science.gov (United States)

    Contrella, Benjamin; Tustison, Nicholas J.; Altes, Talissa A.; Avants, Brian B.; Mugler, John P., III; de Lange, Eduard E.

    2012-03-01

    Although 3He MRI permits compelling visualization of the pulmonary air spaces, quantitation of absolute ventilation is difficult due to confounds such as field inhomogeneity and relative intensity differences between image acquisition; the latter complicating longitudinal investigations of ventilation variation with respiratory alterations. To address these potential difficulties, we present a 4-D segmentation and normalization approach for intra-subject quantitative analysis of lung hyperpolarized 3He MRI. After normalization, which combines bias correction and relative intensity scaling between longitudinal data, partitioning of the lung volume time series is performed by iterating between modeling of the combined intensity histogram as a Gaussian mixture model and modulating the spatial heterogeneity tissue class assignments through Markov random field modeling. Evaluation of the algorithm was retrospectively applied to a cohort of 10 asthmatics between 19-25 years old in which spirometry and 3He MR ventilation images were acquired both before and after respiratory exacerbation by a bronchoconstricting agent (methacholine). Acquisition was repeated under the same conditions from 7 to 467 days (mean +/- standard deviation: 185 +/- 37.2) later. Several techniques were evaluated for matching intensities between the pre and post-methacholine images with the 95th percentile value histogram matching demonstrating superior correlations with spirometry measures. Subsequent analysis evaluated segmentation parameters for assessing ventilation change in this cohort. Current findings also support previous research that areas of poor ventilation in response to bronchoconstriction are relatively consistent over time.

  17. 2H(d,p)3H and 2H(d,n)3He reactions at sub-coulomb energies

    International Nuclear Information System (INIS)

    Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Spartá, R.; Aliotta, M.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Mrazek, J.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

    2012-01-01

    The 2 H( 3 He,p 3 H) 1 H and 2 H( 3 He,n 3 He) 1 H processes have been measured in quasi free kinematics to investigate for the first time the 2 H(d,p) 3 H and 2 H(d,n) 3 He reactions by means of the Trojan Horse Method. The 3 He+d experiment was performed at 18 MeV, corresponding the a d-d energy range from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre Main Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the bare nucleus S(E) factors have been extracted for the first time. They deviate by more than 15% from available direct data with new S(0) values of 57.4±1.8 MeVb for 3 H+p and 60.1±1.9 MeVb for 3 He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

  18. d-3He reaction measurements during fast wave minority heating in PLT

    International Nuclear Information System (INIS)

    Chrien, R.E.; Strachan, J.D.

    1983-01-01

    Time- and energy-resolved d- 3 He fusion reactions have been measured to infer the energy of the d + or He ++ minority ions heated near their cyclotron frequency by the magnetosonic fast wave. The average energy of the reacting 3 He ions during 3 He minority heating is in the range of 100 to 400 keV, as deduced from the magnitude of the reaction rate, its decay time, and the energy spread of the proton reaction products. The observed reaction rate and its scaling with wave power and electron density and temperature are in qualitative agreement with a radial reaction rate model using the minority distribution predicted from quasilinear velocity space diffusion. Oscillations in the reaction rate are observed concurrent with sawtooth and m = 2 MHD activity in the plasma

  19. Static aspects of the fission and fusion of liquid 3He drops

    International Nuclear Information System (INIS)

    Guilleumas, M.; Barranco, M.; Pi, M.

    1992-01-01

    Using an effective 3 He- 3 He interaction, the fission and fusion of 3 He drops have been investigated from a static point of view. The calculations show that a fission barrier develops for these neutral systems, and that their saddle configurations are rather elongate. The transition from oblate to prolate shapes as a function of the angular momentum L, as well as critical values for fission and fusion are discussed for some selected cases. A kind of proximity potential can be extracted from the drop-drop interaction potentials. (author) 33 refs.; 9 figs

  20. A method to quantify tritium inside waste drums: He{sup 3} ingrowth method

    Energy Technology Data Exchange (ETDEWEB)

    Godot, A.; Lepeytre, C.; Hubinois, J.C. [CEA Valduc, Dept. Traitement Materiaux Nucleaires, Service Analyses- Dechets, Lab. Chimie Analytique, 21 - Is-sur-Tille (France); Arseguel, A.; Daclin, J.P.; Douche, C. [CEA Valduc, Dept. Traitement Materiaux Nucleaires, Service Analyses- Dechets, Lab. de Gestion des Dechets Trities, 21 - Is-sur-Tille (France)

    2008-07-15

    This method enables an indirect, non intrusive and non destructive measurement of the Tritium activity in wastes drums. The amount of tritium enclosed inside a wastes drum can be determined by the measurement of the leak rate of {sup 3}He of this latter. The simulation predicts that a few months are necessary for establishing the equilibrium between the {sup 3}He production inside the drum and the {sup 3}He drum leak. In practice, after one year of storage, sampling {sup 3}He outside the drum can be realized by the mean of a confining chamber that collect the {sup 3}He outflow. The apparatus, the experimental procedure and the calculation of tritium activity from mass spectrometric {sup 3}He measurements are detailed. The industrial device based on a confinement cell and the automated process to measure the {sup 3}He amount at the initial time and after the confinement time is described. Firstly, reference drums containing a certified tritium activity (HTO) in addition to organic materials have been measured to qualify the method and to evaluate its performances. Secondly, tritium activity of organic wastes drums issued from the storage building in Valduc have been determined. Results of the qualification and optimised values of the experimental parameters are reported in order to determine the performances of this industrial device. As a conclusion, the apparatus enables the measurement of an activity as low as 1 GBq of tritium in a 200 liters drum containing organic wastes. (authors)

  1. A review of 3He resources and acquisition for use as fusion fuel

    International Nuclear Information System (INIS)

    Wittenberg, L.J.; Camerson, E.N.; Kulcinski, G.L.; Ott, S.H.; Santarius, J.F.; Sviatoslavsky, G.I.; Sviatoslavsky, I.N.; Thompson, H.E.

    1992-01-01

    This paper reports that a combination of man-made and natural resources on earth could provide sufficient 3 He fuel for the technological development of D- 3 He fusion reactors. Helium exists in natural gas wells; however, at the current rate of natural gas usage, this resource would provide 3 He. The radioactive decay of 3 H produced in fission production reactors could yield 110 kg of 3 He by the year 2000 if it were retained. Apparently, a large amount of 3 He exists within the earth's mantle, but it is inaccessible. A significant quantity of 3 He, which could be imported to supply a fusion power industry on earth for hundreds of years, exists on the moon. The solar wind has deposited >1 million tonnes of 3 He in the fine regolith that covers the surface of the moon. The presence of this solar wind gas was confirmed by analyses of the lunar regolith samples brought to earth. A strong correlation is noted between the helium retained and the TiO 2 content of the regolith; consequently, remote-sensing data showing high-titanium-bearing soils in the lunar maria areas have been used to locate potentially rich sites for helium extraction. Surface photographs of Mare Tranquillitatis have shown that nearly 50% of this mare may be minable and capable of supplying ∼7100 tonnes of 3 He. A mobile mining vehicle is proposed for use in the excavation of the soil and the release of the helium and other solar wind gases. The evolved gases would be purified by a combination of permeators and cryogenic techniques to provide a rich resource of H 2 , helium, CO 2 , H 2 O, and N 2 , followed by helium isotopic separation systems

  2. Spent Nuclear Fuel Cask and Storage Monitoring with {sup 4}He Scintillation Fast Neutron Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hee jun; Kelley, Ryan P; Jordan, Kelly A [Univ. of Florida, Florida (United States); Lee, Wanno [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Chung, Yong Hyun [Yonsei Univ., Wonju (Korea, Republic of)

    2014-10-15

    With this increasing quantity of spent nuclear fuel being stored at nuclear plants across S. Korea, the demand exists for building a long-term disposal facility. However, the Korean government first requires a detailed plan for the monitoring and certification of spent fuel. Several techniques have been developed and applied for the purpose of spent fuel monitoring, including the digital Cerenkov viewing device (DCVD), spent fuel attribute tester (SFAT), and FORK detector. Conventional gamma measurement methods, however, suffer from a lack of nuclear data and interfering background radiation. To date, the primary method of neutron detection for spent fuel monitoring has been through the use of thermal neutron detectors such as {sup 3}He and BF{sub 3} proportional counters. Unfolding the neutron spectrum becomes extremely complicated. In an attempt to overcome these difficulties, a new fast neutron measurement system is currently being developed at the University of Florida. This system is based on the {sup 4}He scintillation detector invented by Arktis Radiation Detectors Ltd. These detectors are a relatively new technological development and take advantage of the high {sup 4}He cross-section for elastic scattering at fast neutron energies, particularly the resonance around 1 MeV. This novel {sup 4}He scintillation neutron detector is characterized by its low electron density, leading to excellent gamma rejection. This detector also has a fast response time on the order of nanoseconds and most importantly, preserves some neutron energy information since no moderator is required. Additionally, these detectors rely on naturally abundant {sup 4}He as the fill gas. This study proposes a new technique using the neutron spectroscopy features of {sup 4}He scintillation detectors to maintain accountability of spent fuel in storage. This research will support spent fuel safeguards and the detection of fissile material, in order to minimize the risk of nuclear proliferation

  3. Study of mechanical compression of spin-polarized 3He gas

    International Nuclear Information System (INIS)

    Becker, J.; Heil, W.; Krug, B.; Leduc, M.; Meyerhoff, M.; Nacher, P.J.; Otten, E.W.; Prokscha, T.; Schearer, L.D.; Surkau, R.

    1994-01-01

    We have piloted mechanical compression of spinpolarized 3He by a titanium piston compressor. Questions of materials and design are discussed, followed by a thorough investigation of relaxation sources in the course of compression. The latter are traced mainly to regions with large surface to volume ratio, through which fast passage is demanded, therefore. We conclude from this feasibility study that polarized 3He may be compressed this way up to many bars without serious polarization losses. ((orig.))

  4. Production of intense beams of highly charged heavy ions from RIKEN 18 GHz ECRIS and liquid He free SC-ECRIS

    International Nuclear Information System (INIS)

    Nakagawa, T.; Kidera, M.; Kageyama, T.; Kase, M.; Yano, Y.; Higurashi, Y.; Kurita, T.; Imanaka, M.

    2001-01-01

    We have constructed the high performance ECRISs for RIKEN RI Beam factory project and successfully produced intense beams of highly charged heavy ions. RIKEN 18 GHz ECRIS can especially produce intense beams of medium charge states of heavy ions (1.3 mA of Ar 8+ , 200 eμA of Xe 20+ ) by applying the various techniques, e.g., Al cylinder method, biased electrode method, optimization of the plasma electrode position. Very recently, we successfully produced intense beams of highly charged heavy ions (10 eμA of Xe 30+ , 1 eμA of Xe 36+ ) from the Liquid He free SC-ECRIS with operational frequency of 14 GHz

  5. Explosive He4 burning: I. kinetics of burning at constant temperature and density

    International Nuclear Information System (INIS)

    Khokhlov, A.M.; Ergma, E.V.

    1986-01-01

    The kinetics of He 4 burning at a constant temperature T> 10 9 0 K and a density rho> 10 5 g/cm 3 is considered. The regions of formation of iron group elements and lighter nuclides during He 4 burning are indicated in the rho, T plane. The dependence of the mean atomic number of the nuclides formed on the temperature and the density is determined. For the temperature T ≥4.10 9 0 K a ''neutron flash'' is found, which can lead to a change in the isotopic composition of the r- and s-process elements present. The range of rho and T in which the formation of an excess number of the elements beyond the iron peak is found

  6. Autoionization spectra of He excited by fast (MeV) H/sup +/, He/sup +/, and Li/sup n+/ (n = 1,2,3) ions

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, D.; Arcuni, P.; Bruch, P.; Stoeffler, W.

    1983-01-01

    Autoionization spectra of He following excitation by 1 to 3 MeV H/sup +/, He/sup +/, and Li/sup n+/ (n = 1,2,3) have been measured as a function of observation angle. The (2p/sup 2/)/sup 1/D and (2s2p)/sup 1/P resonances have been examined and a strong dependence on projectile velocities, charge state and observation angle was found.

  7. Search for fourth sound propagation in supersolid 4He

    International Nuclear Information System (INIS)

    Aoki, Y.; Kojima, H.; Lin, X.

    2008-01-01

    A systematic study is carried out to search for fourth sound propagation solid 4 He samples below 500 mK down to 40 mK between 25 and 56 bar using the techniques of heat pulse generator and titanium superconducting transition edge bolometer. If solid 4 He is endowed with superfluidity below 200 mK, as indicated by recent torsional oscillator experiments, theories predict fourth sound propagation in such a supersolid state. If found, fourth sound would provide convincing evidence for superfluidity and a new tool for studying the new phase. The search for a fourth sound-like mode is based on the response of the bolometers to heat pulses traveling through cylindrical samples of solids grown with different crystal qualities. Bolometers with increasing sensitivity are constructed. The heater generator amplitude is reduced to the sensitivity limit to search for any critical velocity effects. The fourth sound velocity is expected to vary as ∞ √ Ρ s /ρ. Searches for a signature in the bolometer response with such a characteristic temperature dependence are made. The measured response signal has not so far revealed any signature of a new propagating mode within a temperature excursion of 5 μK from the background signal shape. Possible reasons for this negative result are discussed. Prior to the fourth sound search, the temperature dependence of heat pulse propagation was studied as it transformed from 'second sound' in the normal solid 4 He to transverse ballistic phonon propagation. Our work extends the studies of [V. Narayanamurti and R. C. Dynes, Phys. Rev. B 12, 1731 (1975)] to higher pressures and to lower temperatures. The measured transverse ballistic phonon propagation velocity is found to remain constant (within the 0.3% scatter of the data) below 100 mK at all pressures and reveals no indication of an onset of supersolidity. The overall dynamic thermal response of solid to heat input is found to depend strongly on the sample preparation procedure

  8. Quantum Evaporation from Liquid 4He by Rotons

    Science.gov (United States)

    Hope, F. R.; Baird, M. J.; Wyatt, A. F. G.

    1984-04-01

    We have shown that rotons as well as phonons can evaporate 4He atoms in a single-quantum process. Measurements of the time of flight and the angular distribution of the evaporated atoms clearly distinguish between evaporation by phonons and rotons. The results indicate that energy and the parallel component of momentum are conserved at the free liquid surface.

  9. Hard photo-disintegration of proton pairs in 3He nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pomerantz, Ishay [Tel Aviv Univ., Ramat Aviv (Israel)

    2011-09-01

    Extensive studies of high-energy deuteron photodisintegration over the past two decades have probed the limits of meson-baryon descriptions of nuclei and nuclear reactions. At high energies, photodisintegration cross sections have been shown to scale as a power law in s (the total cm energy squared), which suggests that quarks are the relevant degrees of freedom. In an attempt to more clearly identify the underlying dynamics at play, JLab/Hall A experiment 03-101 measured the hard photodisintegration of 3He into p-p and p-d pairs at θ c.m. = 90° and Eγ = 0.8 - 4.7 GeV. The basic idea is that the measurement should be able to test theoretical predictions for the relative size of pp versus pn disintegrations. This document presents data for the energy dependence of the high energy 90°c.m. photodisintegration of 3He: dσ/dt(γ + 3He → p + p + nspectator), and dσ/dt(γ + 3He → p + d). The cross sections were observed to scale as a function of s-n where n was found to be 11.1±0.1 and 17.4±0.5 for the two reactions respectively. The degree of scaling found for d σ/dt (γ + 3He → p + d) is the highest degree of scaling ever observed in a nuclear process. The onset of the observed scaling are at photon energy of 2.2 GeV for the pp breakup and 0.7 GeV for the pd breakup. The magnitude of the invariant cross section for pp pair breakup was found to be dramatically lower than for the breakup of pn pairs and theoretical predictions. At energies below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in the pn breakup. The data indicate a transition from three-nucleon hadronic photodisintegration processes at low energies to two-nucleon quark-dominated photodisintegration processes at high energies.

  10. Statistical model and first-principles simulation on concentration of He{sub n}V cluster and He bubble formation in α-Fe and W

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yue-Lin, E-mail: liuyuelin@ss.buaa.edu.cn; Yu, Yang; Dai, Zhen-Hong

    2015-01-15

    Using first-principles calculations, we investigate the stabilities of He and He{sub n}-vacancy (He{sub n}V) clusters in α-Fe and W. Vacancy formation energies are 2.08 eV in α-Fe and 3.11 eV in W, respectively. Single He in both α-Fe and W prefers to occupy the tetrahedral interstitial site. We recalculated the He solution energy considering the effect of zero-point energy (ZPE). The ZPEs of He in α-Fe and W at the tetrahedral (octahedral) interstitial site are 0.072 eV (0.031 eV) and 0.078 eV (0.034 eV), respectively. The trapping energies of single He at vacancy in α-Fe and W are −2.39 eV and −4.55 eV, respectively. By sequentially adding He into vacancy, a monovacancy trap up to 10 He atoms distributing in the vacancy vicinity. Based on the above results combined with statistical model, we evaluate the concentrations of all relevant He{sub n}V clusters as a function of He chemical potential. The critical He{sub n}V concentration is found to be ∼10{sup −40} (atomic) at the critical temperature T = 600 K in α-Fe and T = 1600 K in W, respectively. Beyond the critical He{sub n}V concentrations, considerable He{sub n}V aggregate to form He{sub n}V{sub m} clusters. By further growing of He{sub n}V{sub m}, the He{sub n}V{sub m} clusters grow bigger resulting in the larger He bubble formation.

  11. Damage of niobium surfaces caused by bombardment with 4He+ ions of different energies typical for T-20

    International Nuclear Information System (INIS)

    Guseva, M.I.; Gusev, V.; Martynenko, Yu.V.; Das, S.K.; Kaminsky, M.

    1979-01-01

    The aim of the present studies was to study surface damage due to blistering of both annealed and cold-worked niobium (a candidate first wall material for keV) irradiated sequentially with 4 He + ions with energies of 0.5 to 1800 keV for a total dose of 5.0 C/cm 2 . A typical surface of cold-worked Nb after irradiations with 4 He + ions with increasing energy from 0.5 to 90 keV is shown. The blister diameters range from 0.1 μm to 3 μm, and most of the blisters have exfoliated. The blisters fall into several size classes, the two most dominant ones having most probable blister diameters of approx. 0.27 μm and approx. 2.0 μm. The skin thickness of the larger blisters was measured to be approx. 0.23 μm. Also shown is the same area after irradiation with 150-1800-keV 4 He + irradiation for a dose of 0.66 C/cm 2 . A few additional blisters can be seen. A cold-worked Nb surface that was irradiated only with 150-1800-keV 4 He + ions is also shown. It is seen that prior irradiation with 0.5-90-keV 4 He + helped in significantly reducing blistering. For a total dose of 0.5 C/cm 2 , the erosion yield due to helium blistering of Nb ranges from (5.4 +- 2.0) x 10 -3 to (1.5 +- 0.7) x 10 -2 atoms/ion. For the cold-worked Nb target the results indicate clearly that the 4 He + implantations for the energy range from 0.5 to 90 keV help to reduce both the density and diameter of blisters formed by subsequent He-implantation for the energy ranging from 150 to 1800 keV. 2 figures

  12. Cross sections of the interactions of He nuclei with protons

    International Nuclear Information System (INIS)

    Glagolev, V.V.; Lebedev, R.M.; Pestova, G.D.; Shimansky, S.S.; Kravcikova, M.; Seman, M.; Sandor, L.; Dirner, A.; Hlavacova, J.; Martinska, G.; Urban, J.; Khairetdinov, K.U.; Braun, H.; Gerber, J.P.; Juillot, P.; Michalon, A.; Kacharava, A.K.; Menteshashvili, Z.P.; Nioradze, M.S.; Salukvadze, Z.R.; Sobczak, T.; Stepaniak, J.

    1993-01-01

    4 He-p collisions at two values of 4 He momenta 8.6 GeV/c and 13.6 GeV/c as well as the 3 He-p collisions at 13.5 GeV/c have been studied using the one-meter JINR hydrogen bubble chamber. Total, elastic, topological and reaction cross sections have been measured. The cross sections have been determined on a sample of minimum biased events. (orig.)

  13. Does the excited state of the 3He nucleus exist?

    International Nuclear Information System (INIS)

    Barabanov, A.L.

    1994-01-01

    The suggestion is made that the excited state of the 3 He nucleus found out recently in the reaction has spin and parity 1/2 + and the same configuration that the ground open of 6 He. It is shown that in an elastic nd-scattering a resonance associated with the excited state may be absent due to destructive interference of potential and resonant scattering phases

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

    Science.gov (United States)

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

    2012-01-27

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

  15. Angular distribution measurements of {sup 6}Li(p,{alpha}){sup 3}He reaction at 140 keV proton energy using nuclear track detectors

    Energy Technology Data Exchange (ETDEWEB)

    Al-Jarallah, M.I. E-mail: mibrahim@kfupm.edu.sa; Naqvi, A.A.; Abu-Jarad, F.A.; Fazal-ur-Rehman; Durrani, S.M.A.; Kidwai, S

    2001-06-01

    Angular distributions of a {sup 6}Li(p,{alpha}) {sup 3}He reaction were measured at six angles for 140 keV proton energy using nuclear track detectors (NTDs). The measurements were carried out over 60 deg. -160 deg. lab. angles in 20 deg. increments using a scattering chamber of 80 deg. beam line of the 350 kV accelerator. A semiconductor silicon surface barrier (SSB) detector was placed at +160 deg. and was used as a monitor. The results have shown that the CR-39 detector has excellent capabilities to distinguish 1.4-2.7 MeV {alpha}+ {sup 3}He particles from the {sup 6}Li(p,{alpha}) {sup 3}He reaction and 8-9.4 MeV {alpha}-particles from the {sup 7}Li(p,{alpha}) {sup 4}He reaction through their track diameters. However, it was not possible to distinguish between the 2.3 MeV {sup 3}He ions and the 1.7 MeV {sup 4}He ions from the {sup 6}Li(p,{alpha}) {sup 3}He reaction from their track diameter measurements, but it was possible to differentiate between the two, from the darker contrast of the {sup 3}He particles caused by its deeper tracks as compared to those of {sup 4}He.

  16. Diffraction scattering and disintegration of 3He nuclei by atomic nuclei

    International Nuclear Information System (INIS)

    Koval'chuk, V.I.

    2006-01-01

    Within diffraction model framework a method of cross sections calculation for scattering and disintegration of weakly-bounded two-clustered nuclei by nuclei when both of its clusters are changed has been proposed. The experimental elastic scattering cross sections of 3 He by 40 Ca, 90 Zr and coincidence spectra of disintegration products from 28 Si( 3 He,dp) have been described

  17. π--induced single charge exchange on polarized 3He

    International Nuclear Information System (INIS)

    Zhao, Q.; Burleson, S.; Blanchard, T.

    1995-01-01

    Asymmetries, A y , for the (π - ,π 0 ) reaction on polarized 3 He were measured using the pion beam of the P3W channel at LAMPF. The π 0 were detected with the new Neutral Meson Spectrometer (NMS) in coincidence with recoiling tritons. The recoil detector consisted of scintillation-counter telescopes and a wire chamber that provided energy-loss and direction information, respectively. The polarized gaseous 3 He target developed at TRIUMF was modified and run with the use of two diode lasers. Polarizations were typically 50%. The A y taken at T π = 200 MeV between 60 and 105 degrees were found to be strongly angle-dependent. The results will be compared with the theoretical predictions

  18. Test of sup 3 He-based neutron polarizers at NIST

    CERN Document Server

    Jones, G L; Thompson, A K; Chowdhuri, Z; Dewey, M S; Snow, W M; Wietfeldt, F E

    2000-01-01

    Neutron spin filters based on polarized sup 3 He are useful over a wide neutron energy range and have a large angular acceptance among other advantages. Two optical pumping methods, spin-exchange and metastability-exchange, can produce the volume of highly polarized sup 3 He gas required for such neutron spin filters. We report a test of polarizers based on each of these two methods on a new cold, monochromatic neutron beam line at the NIST Center for Neutron Research.

  19. Differential cross section measurement for the {sup 6}Li(n,t){sup 4}He Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Guohui, Zhang; Guoyou, Tang; Jinxiang, Chen; Zhaomin, Shi [Beijing Univ., Beijing (China). Inst. of Heavy Ion Physics and MOE Key Laboratory of Heavy Ion Physics; Zemin, Chen [Tsinghua Univ., Beijing (China). Dept. of Physics; Gledenov, Yu M; Sedysheva, M; Khuukhenkhuu, G [Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics, Dubna (Russian Federation)

    2002-06-01

    The differential cross sections and integrated cross sections of the {sup 6}Li(n,t){sup 4}He reaction were measured at 1.85 and 2.67 MeV by using a gridded ionization chamber. Neutrons were produced through the T(p, n){sup 3}He reaction. The absolute neutron flux was determined through the {sup 238}U(n, f) reaction. Present results are compared with existing data.

  20. Determination of relative populations of the magnetic sub-levels of the 4 1D level of HeI excited by heavy ion impact

    International Nuclear Information System (INIS)

    Carre, M.; Zgainski, A.; Gaillard, M.; Nouh, M.; Lombardi, M.

    1981-01-01

    The theoretical study of the depolarization of a transition, emitted from an excited atomic level J = 2, by a static electric field leads to the development of a new experimental method and the measurement of the relative population of the Zeeman sub-levels. This method is applied to the study of the 4 1 D level of HeI excited by several heavy ions (Li + , Ne + , Na + and Mg + ) at intermediate energy between 6 and 40 keV. From the obtained results, we derive informations on the target excitation phenomena: in particular present evidence for a long-range interaction, due to the ion charge, in the output channel of the collision [fr

  1. Spectroscopic abundance analyses of the 3He stars HD 185330 and 3 Cen A

    Science.gov (United States)

    Sadakane, Kozo; Nishimura, Masayoshi

    2018-04-01

    Abundances of 21 elements in two 3He stars, HD 185330 and 3 Cen A, have been analysed relative to the well-studied sharp-lined B3 V star ι Her. Six elements (P, Ti, Mn, Fe, Ni, and Br) are over-abundant in these two peculiar stars, while six elements (C, O, Mg, Al, S, and Cl) are under-abundant. Absorption lines of the two rarely observed heavy elements Br II and Kr II are detected in both stars and these elements are both over-abundant. The centroid wavelengths of the Ca II infrared triplet lines in these stars are redshifted relative to those lines in ι Her and the presence of heavy isotopes of Ca (mass number 44-46) in these two stars is confirmed. In spite of these similarities, there are several remarkable differences in abundance pattern between these two stars. N is under-abundant in HD 185330, as in many Hg-Mn stars, while it is significantly over-abundant in 3 Cen A. P and Ga are both over-abundant in 3 Cen A, while only P is over-abundant and no trace of absorption line of Ga II can be found in HD 185330. Large over-abundances of Kr and Xe are found in both stars, while the abundance ratio Kr/Xe is significantly different between them (-1.4 dex in HD 185330 and +1.2 dex in 3 Cen A). Some physical explanations are needed to account for these qualitative differences.

  2. The influence of (n-n')-mixing processes in He*(n)+He(1s2) collisions on He*(n) atoms' populations in weakly ionized helium plasmas

    International Nuclear Information System (INIS)

    Mihajlov, A.A.; Ignjatovic, Lj.M.; Sreckovic, V.A.; Djuric, Z.

    2008-01-01

    The results of semi-classical calculations of rate coefficients of (n-n ' )-mixing processes due to collisions of Rydberg atoms He*(n) with He(1s 2 ) atoms are presented. It is assumed that these processes are caused by the resonant energy exchange within the electron component of He*(n)+He collision system. The method is realized through the numerical simulation of the (n-n ' )-mixing processes, and is applied for calculations of the corresponding rate coefficients. The calculations are performed for the principal quantum numbers n,n ' in ranges 4≤n ' ≤10, and the atom and electron temperatures, T a ,T e , in domains 5000K≤T a ≤T e ≤20000K. It is shown that the (n-n ' )-mixing processes can significantly influence the populations of Rydberg atoms in non-equilibrium weakly ionized helium plasmas with ionization degree ∼10 -4 . Therefore, these processes have to be included in the appropriate models of such plasmas

  3. U-Th-He dating of diamond-forming C-O-H fluids and mantle metasomatic events

    Science.gov (United States)

    Weiss, Y.; Class, C.; Goldstein, S. L.; Winckler, G.; Kiro, Y.

    2017-12-01

    Carbon- and water-rich (C-O-H) fluids play important roles in the global material circulation, deep Earth processes, and have major impacts on the sub-continental lithospheric mantle (SCLM). Yet the origin and composition of C-O-H fluids, and the timing of fluid-rock interaction, are poorly constrained. `Fibrous' diamonds encapsulate C-O-H mantle fluids as μm-scale high-density fluid (HDF) inclusions. They can be directly sampled, and offer unique opportunities to investigate metasomatic events involving C-O-H fluids and the SCLM through Earth history. Until now no technique has provided reliable age constraints on HDFs. We applied a new in-vacuum crushing technique to determine the He abundances and 3He/4He ratios of HDFs in diamonds from the Kaapvaal lithosphere, South Africa. Three diamonds with saline HDFs have 3He/4He=3-4Ra. In 4He/3He vs 238U/3He space they define an `isochron' age of 96±45Ma, representing the first radiometric age reported for HDFs, and thus for C-O-H mantle fluids. In addition, a diamond with silicic HDFs and two that carry carbonatitic HDFs have low 3He/4He=0.07-0.6Ra. Using the measured U, Th, 4He and 3He contents of these diamonds, and the equation for 4He production from U-Th decay, we calculate 3He/4He as a function of time. Metasomatic fluids are derived from MORB, SCLM or subducted components with R/Ra=3-10, and this is assumed as the HDFs initial composition. The silicic and carbonatitic HDFs signify two older metasomatic events at 350 and 850 Ma, respectively. Thus, our new data reveal 3 metasomatic episodes in the Kaapvaal SCLM during the last 1 Ga, each by a different metasomatic agent. These 3 episodes correspond to late-Mesozoic kimberlite eruptions at 85 Ma, and the regional Namaqua-Natal and Damara Orogenies at 1 Ga and 500 Ma. We propose that the radioactive U-Th-He system in HDF-bearing diamonds can be used as a tool to provide meaningful radiometric ages of deep C-O-H fluids, and the timing of SCLM metasomatic events.

  4. Effect of thermal 3He minorities on knock-on tail formation and the resulting neutron emission spectrum modification in deuterium-tritium plasmas

    International Nuclear Information System (INIS)

    Matsuura, H; Nakao, Y; Nakamura, M; Mitarai, O

    2011-01-01

    The knock-on tail formations in fuel-ion velocity distribution functions by energetic alpha particles (by the T(d,n) 4 He reaction) and protons (by the D(d,p)T and 3 He(d,p) 4 He reactions) are investigated by simultaneously solving the Boltzmann-Fokker-Planck (BFP) equations for deuteron, triton, 3 He, alpha particle and proton in an ITER-like (DT) plasma admixed with a small amount of 3 He. As a result of the 3 He inclusion, a fraction of the transferred energy from energetic ions to thermal deuterons and tritons via nuclear plus interference (NI) scattering is reduced. Owing to the NI scattering of the energetic protons by fuel ions, the latter are knocked up to higher energies. The knocking-up effect of fuel ions is enhanced with increasing 3 He concentration. It is shown that if 3 He with relative concentration of 4.2%, i.e. n 3 He /n e =0.042, is included in T e = 20 keV, n e = 9.5 x 10 19 m -3 plasma, the magnitude of the knock-on tail in deuteron distribution function in 300 keV-3 MeV energy range is reduced by about 15% from the value when 3 He is not externally supplied. Such knock-on tail reduction also results in alternation of the non-Gaussian neutron emission spectrum with energies less than ∼13 MeV and above ∼15 MeV.

  5. Coherent deeply virtual Compton scattering off 3He and neutron generalized parton distributions

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo

    2014-06-01

    Full Text Available It has been recently proposed to study coherent deeply virtual Compton scattering (DVCS off 3He nuclei to access neutron generalized parton distributions (GPDs. In particular, it has been shown that, in Impulse Approximation (IA and at low momentum transfer, the sum of the quark helicity conserving GPDs of 3He, H and E, is dominated by the neutron contribution. This peculiar result makes the 3He target very promising to access the neutron information. We present here the IA calculation of the spin dependent GPD H See Formula in PDF of 3He. Also for this quantity the neutron contribution is found to be the dominant one, at low momentum transfer. The known forward limit of the IA calculation of H See Formula in PDF , yielding the polarized parton distributions of 3He, is correctly recovered. The extraction of the neutron information could be anyway non trivial, so that a procedure, able to take into account the nuclear effects encoded in the IA analysis, is proposed. These calculations, essential for the evaluation of the coherent DVCS cross section asymmetries, which depend on the GPDs H,E and H See Formula in PDF , represent a crucial step for planning possible experiments at Jefferson Lab.

  6. Optimum transmission for a 3He neutron polarizer

    International Nuclear Information System (INIS)

    Tasset, F.; Ressouche, E.

    1995-01-01

    Following recent achievements in polarizing gaseous 3 He targets by optical pumping at room temperature, polarized helium-3 is now the most promising polarizer for thermal and epithermal neutrons and should soon compete favorably with existing Heusler polarizing crystals. Because it is gaseous, a degree of freedom exists in such a filter: the pressure of the gas in the cell. This parameter allows a choice to be made in the filter design: for a given polarization of 3 He, one is able to increase the pressure, to favor neutron beam polarization, or to stay at relatively low pressure to favor the filter's transmission. In this paper, we discuss this point in the framework of a classical polarized neutron experiment, and we compare our more general results with the quality factor Q=P√(T), which is generally taken as standard for such a filter. (orig.)

  7. Hyperpolarized {sup 3}He magnetic resonance imaging: Preliminary evaluation of phenotyping potential in chronic obstructive pulmonary disease

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, Lindsay, E-mail: lmathew@imaging.robarts.ca [Imaging Research Laboratories, Robarts Research Institute, London (Canada); Department of Medical Biophysics, University of Western Ontario, London (Canada); Kirby, Miranda, E-mail: mkirby@imaging.robarts.ca [Imaging Research Laboratories, Robarts Research Institute, London (Canada); Department of Medical Biophysics, University of Western Ontario, London (Canada); Etemad-Rezai, Roya, E-mail: Roya.EtemadRezai@lhsc.on.ca [Department of Medical Imaging, University of Western Ontario (Canada); Wheatley, Andrew, E-mail: awheat@imaging.robarts.ca [Imaging Research Laboratories, Robarts Research Institute, London (Canada); McCormack, David G., E-mail: David.McCormack@lhsc.on.ca [Imaging Research Laboratories, Robarts Research Institute, London (Canada); Division of Respirology, Department of Medicine, University of Western Ontario, London (Canada); Lawson Health Research Institute, London (Canada); Parraga, Grace, E-mail: gep@imaging.robarts.ca [Imaging Research Laboratories, Robarts Research Institute, London (Canada); Department of Medical Biophysics, University of Western Ontario, London (Canada); Department of Medical Imaging, University of Western Ontario (Canada); Lawson Health Research Institute, London (Canada)

    2011-07-15

    Rationale and objectives: Emphysema and small airway obstruction are the pathological hallmarks of chronic obstructive pulmonary disease (COPD). The aim of this pilot study in a small group of chronic obstructive pulmonary disease (COPD) patients was to quantify hyperpolarized helium-3 ({sup 3}He) magnetic resonance imaging (MRI) functional and structural measurements and to explore the potential role for {sup 3}He MRI in detecting the lung structural and functional COPD phenotypes. Materials and methods: We evaluated 20 ex-smokers with stage I (n = 1), stage II (n = 9) and stage III COPD (n = 10). All subjects underwent same-day plethysmography, spirometry, {sup 1}H MRI and hyperpolarized {sup 3}He MRI at 3.0 T. {sup 3}He ventilation defect percent (VDP) was generated from {sup 3}He static ventilation images and {sup 1}H thoracic images and the {sup 3}He apparent diffusion coefficient (ADC) was derived from diffusion-weighted MRI. Results: Based on the relative contribution of normalized ADC and VDP, there was evidence of a predominant {sup 3}He MRI measurement in seven patients (n = 3 mainly ventilation defects or VDP dominant (VD), n = 4 mainly increased ADC or ADC dominant (AD)). Analysis of variance (ANOVA) showed significantly lower ADC for subjects with predominantly elevated VDP (p = 0.02 compared to subjects with predominantly elevated ADC; p = 0.008 compared to mixed group) and significantly decreased VDP for subjects with predominantly elevated ADC (p = 0.003, compared to mixed group). Conclusion: In this small pilot study, a preliminary analysis shows the potential for {sup 3}He MRI to categorize or phenotype COPD ex-smokers, providing good evidence of feasibility for larger prospective studies.

  8. Tritium/3He measurements in young groundwater: Progress in applications to complex hydrogeological systems

    Science.gov (United States)

    Schlosser, Peter; Shapiro, Stephanie D.; Stute, Martin; Plummer, Niel

    2000-01-01

    Tritium/3He dating has been applied to many problems in groundwater hydrology including, for example, determination of circulation patterns, mean residence times, recharge rates, or bank infiltration. Here, we discuss recent progress in the application of the tritium/3He dating method to sites with complex hydrogeological settings. Specifically, we report on tritium/3He dating at sites with (a) river infiltration into the basaltic fractured rock aquifer of the Eastern Snake River Plain, and (b) river infiltration through sinkholes into the karstic limestone Upper Floridian aquifer near Valdosta, Georgia.Tritium/3He dating has been applied to many problems in groundwater hydrology including, for example, determination of circulation patterns, mean residence times, recharge rates, or bank infiltration. Here, we discuss recent progress in the application of the tritium/3He dating method to sites with complex hydrogeological settings. Specifically, we report on tritium/3He dating at sites with (a) river infiltration into the basaltic fractured rock aquifer of the Eastern Snake River Plain, and (b) river infiltration through sinkholes into the karstic limestone Upper Floridian aquifer near Valdosta, Georgia.

  9. Measurement of the 6He Decay Produced by the 9Be(n, α) 6 He Reaction

    Science.gov (United States)

    Cook, Katelyn; Coats, Micah; Yuly, Mark; Padalino, Stephen; Sangster, Craig; Regan, Sean

    2016-10-01

    The OMEGA laser at LLE is routinely used to implode gas-filled capsules to study light ion fusion reaction rates of interest to stellar nucleosynthesis. As a first step toward a possible measurement of the 3H(t,γ)6He radiative capture reaction, a detector system capable of measuring the 801 ms half-life of 6He has been developed and is being tested using 6He nuclei produced via the 9Be(n,α)6He reaction. Deuterons from the SUNY Geneseo tandem Pelletron produce neutrons in a thick deuterated polyethylene target via the 2H(d,n)3He reaction. These neutrons are allowed to strike a beryllium target placed in front of a silicon ΔE-E detector telescope, which is used to identify the β particles from 6He decay. Following an approximately five second long activation period, the beryllium sample is immediately counted for about five seconds. The pulse heights for each detector and the timestamp are recorded using a specially configured femtoDAQ acquision system and used to measure the decay curve. Funded in part by a Grant from the DOE through the Laboratory for Laser Energetics.

  10. Excitation function of elastic scattering on 12C + 4He system, at low energies

    International Nuclear Information System (INIS)

    Perez-Torres, R.; Aguilera, E. F.; Martinez-Quiroz, E.; Murillo, G.; Belyaeva, T. L.; Maldonado-Velazquez, M.

    2011-01-01

    Interactions in the 12 C + 4 He system are of great interest in astrophysics and to help determine the relative abundances of elements in stars, at the end of helium burning [1, 2]. The Instituto Nacional de Investigaciones Nucleares (ININ) in Mexico, have made measurements of elastic scattering for this system, using the inverse kinematics method with thick white gas [3, 4], for E CM (0.5 - 4 MeV) θ CM = 180 o . In this work we obtain excitation functions of elastic scattering of 12 C + 4 He system with angular and energy dependence; E CM = 0.5 - 4 MeV and θ CM 100 o -170 o .Using inverse kinematics method with thick white gas and energy loss tables. (Author)

  11. Multipole pair vibrations in superfluid 3He

    International Nuclear Information System (INIS)

    Baldo, M.; Giansiracusa, G.; Lombardo, U.; Pucci, R.; Petronio, G.

    1978-01-01

    Starting from a path integral formation of the 3 He superfluidity, the authors study the pair vibrations around the BCS solution. For both the BW and ABM states get a set of possible excitations. In particular it is shown that a new type of excitation is present for pure 1 = 2 spin singlet vibration. (Auth.)

  12. Quercetin suppresses HeLa cells by blocking PI3K/Akt pathway.

    Science.gov (United States)

    Xiang, Tao; Fang, Yong; Wang, Shi-Xuan

    2014-10-01

    To explore the effect of quercetin on the proliferation and apoptosis of HeLa cells, HeLa cells were incubated with quercetin at different concentrations. Cell viability was evaluated by MTT assay, cell apoptosis was detected by Annexin-V/PI double labeled cytometry and DNA ladder assay. Cell cycle was flow cytometrically determined and the morphological changes of the cells were observed under a fluorescence microscope after Hoechst 33258 staining and the apoptosis-related proteins in the HeLa cells were assessed by Western blotting. The results showed that quercetin significantly inhibited the growth of HeLa cells and induced obvious apoptosis in vitro in a time- and dose-dependent manner. Moreover, quercetin induced apoptosis of HeLa cells in cell cycle-dependent manner because quercetin could induce arrest of HeLa cells at G0/G1 phase. Quercetin treatment down-regulated the expression of the PI3K and p-Akt. In addition, quercetin could down-regulate expression of bcl-2, up-regulate Bax, but exerted no effect on the overall expression of Akt. We are led to conclude that quercetin induces apoptosis via PI3k/Akt pathways, and quercetin has potential to be used as an anti-tumor agent against human cervix cancer.

  13. Towards accurate T-3He Q-value

    Energy Technology Data Exchange (ETDEWEB)

    Eronen, Tommi; Hoecker, Martin; Ketter, Jochen; Streubel, Sebastian; Blaum, Klaus [Max-Planck Institut fuer Kernphysik, Heidelberg (Germany); Van Dyck, Robert S. Jr. [Department of Physics, University of Washington, Seattle, WA (United States)

    2013-07-01

    Great efforts have been put forward to determine the neutrino mass from tritium β decay. The most prominent experimental setup, KATRIN, is expected to deliver an upper limit to the neutrino mass that is one order of magnitude more stringent than the current value by measuring the endpoint and the shape of the β spectrum of the tritium decay. The endpoint energy (assuming zero neutrino mass) can also be deduced from the Q-value of the decay by measuring the mass difference of tritium and the daughter {sup 3}He using high-resolution mass spectrometry. Such a measurement would give an excellent, independent calibration point for the KATRIN experiment to deduce its systematics. Our mass-difference measurement utilizes the Tritium- Helium double Penning trap (THe-Trap) setup. Based on the anharmonic cyclotron frequency determination method pioneered at the University of Washington, Seattle, precision at the level of 1 part in 10{sup 11} in the T/{sup 3}He mass ratio is expected. In this contribution, I describe the motivation, the principle, current status, and expectations of the experiment.

  14. Interspecies Ion Diffusion Studies using DT, DT(3He), and DT(H) Implosions

    Science.gov (United States)

    Kim, Y.; Herrmann, H. W.; Schmitt, M. J.; Kagan, G.; McEvoy, A. M.; Hoffman, N. M.; Gales, S.; Leatherland, A.; Gatu Johnson, M.; Frenje, J.; Glevov, V. Yu; Forrest, C.

    2015-11-01

    Anomalous ICF yield degradation has been observed from gas fills containing mixtures (i.e., D(3He), DT(3He), D(Ar), and even DT). Interspecies ion diffusion theory has been suggested as a possible cause resulting from gradient-driven diffusion (i.e., pressure, electric potential, and temperature) which forces lower mass ions away from core and higher mass ions toward core. The theory predicts hydrogen addition to deuterium or tritium should result in increased yield compared to expected yield, which is opposite to 3He addition. At Omega laser facility, we have tested hydro-equivalent fills of DT, DT(3He), and DT(H) with the assumption that same fuel mass and particle pressure will provide identical convergence. Preliminary results verify a factor of 2 yield reduction relative to scaling when 3He added to DT. At DT(H) case, however, no significant yield degradation or a slight yield enhancement was observed which agrees with the interspecies ion diffusion theory. Detailed experiment results and simulation are needed to confirm the initial observation.

  15. High-momentum excitations in liquid He4

    International Nuclear Information System (INIS)

    Parlinski, K.

    1973-01-01

    The dynamic structure factor of liquid He 4 is calculated on the basis of four moments. One of the functions, which corresponds to the centre of main distribution observed by the neutron scattering method, exhibits oscillatory deviations from the energy of free helium atoms. These oscillations have been found to be in good agreement with the experimental data of Cowley and Woods. The width of the same distribution, approximated by the Gaussian form, is also estimated and general agreement is established. (author)

  16. Momentum characteristics of spectators in fragmentation of 4He nuclei

    International Nuclear Information System (INIS)

    Glagolev, V.V.; Lebedev, R.M.; Strel'tsov, V.N.

    1985-01-01

    Some characteristics of 2 H, 3 H, 3 He fragments from 4 Hep interaction at 8.6 GeV/c have been studied. A numerical procedure, based on Monte-Carlo method, for getting the wave function of relative motion of nucleons or groups of nucleons in nucleus is proposed to describe the fragment momentum spectra and the asymmetry in Treiman-Yang angle distribution. The agreement between computed and experimental results is sufficient if one takes into account the experimental errors and the nucleus binding energy

  17. Three-body interactions and the elastic constants of hcp solid 4He

    Science.gov (United States)

    Barnes, Ashleigh L.; Hinde, Robert J.

    2017-09-01

    The effect of three-body interactions on the elastic properties of hexagonal close packed solid 4He is investigated using variational path integral (VPI) Monte Carlo simulations. The solid's nonzero elastic constants are calculated, at T = 0 K and for a range of molar volumes from 7.88 cm3/mol to 20.78 cm3/mol, from the bulk modulus and the three pure shear constants C0, C66, and C44. Three-body interactions are accounted for using our recently reported perturbative treatment based on the nonadditive three-body potential of Cencek et al. Previous studies have attempted to account for the effect of three-body interactions on the elastic properties of solid 4He; however, these calculations have treated zero point motions using either the Einstein or Debye approximations, which are insufficient in the molar volume range where solid 4He is characterized as a quantum solid. Our VPI calculations allow for a more accurate treatment of the zero point motions which include atomic correlation. From these calculations, we find that agreement with the experimental bulk modulus is significantly improved when three-body interactions are considered. In addition, three-body interactions result in non-negligible differences in the calculated pure shear constants and nonzero elastic constants, particularly at higher densities, where differences of up to 26.5% are observed when three-body interactions are included. We compare to the available experimental data and find that our results are generally in as good or better agreement with experiment as previous theoretical investigations.

  18. Vacancy effects on the formation of He and Kr cavities in 3C-SiC irradiated and annealed at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zang, Hang; Jiang, Weilin; Liu, Wenbo; Devaraj, Arun; Edwards, Danny J.; Henager, Charles H.; Kurtz, Richard J.; Li, Tao; He, Chaohui; Yun, Di; Wang, Zhiguang

    2016-12-01

    Polycrystalline 3C-SiC was sequentially irradiated at 400 and 750°C with 120 keV He2+ and 4 MeV Kr15+ ions to E21 and 4E20 ions/m2 with profiles of the implanted species peaked at 450 and 1500 nm, respectively. The masked overlapping irradiation created three study areas of He2+, Kr15+ and He2+ + Kr15+ implanted SiC. The doses at the depth of the peak He concentration in He2+ and He2+ + Kr15+ implanted SiC correspond to 4 and 25 dpa. The sample was subsequently annealed at 1600°C for 3 h in vacuum and characterized using cross-sectional transmission electron microscopy and energy-dispersive x-ray spectroscopy. Compared to the He2+ implanted SiC, He cavities show a smaller size and higher density in the co-implanted SiC. At 25 dpa, He presence in the co-implanted 3C-SiC significantly promotes He cavity growth, as contrasted to the smaller voids formed without He in the Kr15+ irradiated SiC at the same dose. In addition, local Kr migration and trapping at cavities occur, but long-range Kr diffusion in SiC is not observed up to 1600°C.

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

    International Nuclear Information System (INIS)

    Weinriefer, Markus

    2011-01-01

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

  20. 3-(3-Hydroxy-4-methoxyphenyl)-4-(3,4,5-trimethoxyphenyl)-1,2,5-selenadiazole (G-1103), a novel combretastatin A-4 analog, induces G2/M arrest and apoptosis by disrupting tubulin polymerization in human cervical HeLa cells and fibrosarcoma HT-1080 cells.

    Science.gov (United States)

    Zuo, Daiying; Guo, Dandan; Jiang, Xuewei; Guan, Qi; Qi, Huan; Xu, Jingwen; Li, Zengqiang; Yang, Fushan; Zhang, Weige; Wu, Yingliang

    2015-02-05

    Microtubule is a popular target for anticancer drugs. In this study, we describe the effect 3-(3-hydroxy-4-methoxyphenyl)-4-(3,4,5-trimethoxyphenyl)-1,2,5-selenadiazole (G-1103), a newly synthesized analog of combretastatin A-4 (CA-4), showing a strong time- and dose-dependent anti-proliferative effect on human cervical cancer HeLa cells and human fibrosarcoma HT-1080 cells. We demonstrated that the growth inhibitory effects of G-1103 in HeLa and HT-1080 cells were associated with microtubule depolymerization and proved that G-1103 acted as microtubule destabilizing agent. Furthermore, cell cycle analysis revealed that G-1103 treatment resulted in cell cycle arrest at the G2/M phase in a time-dependent manner with subsequent apoptosis induction. Western blot analysis revealed that down-regulation of cdc25c and up-regulation of cyclin B1 was related with G2/M arrest in HeLa and HT-1080 cells treatment with G-1103. In addition, G-1103 induced HeLa cell apoptosis by up-regulating cleaved caspase-3, Fas, cleaved caspase-8 expression, which indicated that G-1103 induced HeLa cell apoptosis was mainly associated with death receptor pathway. However, G-1103 induced HT-1080 cell apoptosis by up-regulating cleaved caspase-3, Fas, cleaved caspase-8, Bax and cleaved caspase-9 expression and down-regulating anti-apoptotic protein Bcl-2 expression, which indicated that G-1103 induced HT-1080 cell apoptosis was associated with both mitochondrial and death receptor pathway. Taken together, all the data demonstrated that G-1103 exhibited its antitumor activity through disrupting the microtubule assembly, causing cell cycle arrest and consequently inducing apoptosis in HeLa and HT-1080 cells. Therefore, the novel compound G-1103 is a promising microtubule inhibitor that has great potentials for therapeutic treatment of various malignancies. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.