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Sample records for 3he hp 3he

  1. Electrodisintegration of 3He

    An experimental study of the reaction 3He(e, d) e'p was carried out by measuring differential cross sections of deuterons as a function of deuteron energy and angle for three incident electron energies. The electrodisintegration cross section was also calculated using an Irving-Gunn wave function for the ground state with a plane wave for the final-state. As in the case of photodisintegration calculations the result indicates the need for including complete final-state rescattering effects

  2. ^3He Spin Pump

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

    2009-03-01

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

  3. The 3He Supply Problem

    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.

  4. Progression of Emphysema Evaluated by MRI Using Hyperpolarized 3He (HP 3He) Measurements in Patients with Alpha-1-Antitrypsin (A1AT) Deficiency Compared with CT and Lung Function Tests

    Stavngaard, T.; Vejby Soegaard, L. (Danish Research Center for Magnetic Resonance, Copenhagen Univ. Hospital Hvidovre, Hvidovre (Denmark)); Batz, M. (Inst. of Physics, Johannes Gutenberg Univ., Mainz (Germany)); Schreiber, L.M. (Dept. of Interventional and Diagnostic Radiology, Johannes Gutenberg Univ. Medical School, Mainz (Germany)); Dirksen, A. (Dept. of Respiratory Medicine, Gentofte Hospital, Univ. of Copenhagen, Copenhagen (Denmark))

    2009-11-15

    Background: The progression of emphysema is traditionally measured by pulmonary function test, with forced expiratory volume in 1 s (FEV1) being the most accepted and used measurement. However, FEV1 is insensitive in detecting mild/slow progression of emphysema because of low reproducibility as compared to yearly decline. Purpose: To investigate the progression of emphysema over a period of 2 years using diffusion-weighted hyperpolarized (HP) 3He magnetic resonance imaging (MRI) in patients with alpha-1-antitrypsin (A1AT) deficiency. Material and Methods: Nine patients with severe A1AT deficiency were studied over a period of 2 years (baseline, year 1, and year 2) with HP 3He MRI using apparent diffusion coefficient (ADC), lung function tests (FEV1 and carbon monoxide lung diffusion capacity [DL,CO]), and computed tomography (CT) using densitometric parameters (15th percentile density [CT-PD15] and relative area of emphysema below -910 HU [CT-RA-910]). Results: Seven patients were scanned three times, one patient two times, and one patient only at baseline. The mean increase in ADC values from first to last HP 3He MR scanning was 3.8% (0.014 cm2/s [SD 0.024 cm2/s]; not significant). The time trends for FEV1, DL,CO, CT-PD15, and CT-RA-910 were all statistically significant. We found a high correlation between ADC and DL,CO (P<0.001). Conclusion: This pilot study indicates the possible use of nonionizing HP 3He MRI for monitoring the progression of emphysema. However, in the future, larger studies are needed to confirm these preliminary results

  5. Progression of Emphysema Evaluated by MRI Using Hyperpolarized 3He (HP 3He Measurements in Patients with Alpha-1-Antitrypsin (A1AT) Deficiency Compared with CT and Lung Function Tests

    Background: The progression of emphysema is traditionally measured by pulmonary function test, with forced expiratory volume in 1 s (FEV1) being the most accepted and used measurement. However, FEV1 is insensitive in detecting mild/slow progression of emphysema because of low reproducibility as compared to yearly decline. Purpose: To investigate the progression of emphysema over a period of 2 years using diffusion-weighted hyperpolarized (HP) 3He magnetic resonance imaging (MRI) in patients with alpha-1-antitrypsin (A1AT) deficiency. Material and Methods: Nine patients with severe A1AT deficiency were studied over a period of 2 years (baseline, year 1, and year 2) with HP 3He MRI using apparent diffusion coefficient (ADC), lung function tests (FEV1 and carbon monoxide lung diffusion capacity [DL,CO]), and computed tomography (CT) using densitometric parameters (15th percentile density [CT-PD15] and relative area of emphysema below -910 HU [CT-RA-910]). Results: Seven patients were scanned three times, one patient two times, and one patient only at baseline. The mean increase in ADC values from first to last HP 3He MR scanning was 3.8% (0.014 cm2/s [SD 0.024 cm2/s]; not significant). The time trends for FEV1, DL,CO, CT-PD15, and CT-RA-910 were all statistically significant. We found a high correlation between ADC and DL,CO (P3He MRI for monitoring the progression of emphysema. However, in the future, larger studies are needed to confirm these preliminary results

  6. A multipurpose 3He refrigerator

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

    2006-10-01

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

  7. The Panofsky ratio in 3He

    The branching ratios have been measured for γ-ray channels produced by π- stopping in liquid 3He. The results for the Panofsky ratio are P3 = ω(π-3He → π0t)/ω(π-3He → γt) = 2.83±0.07, and for the ratio of the radiative breakup channels, B3 = ω(π-3He → γnd+γnnp)/ω(π-3He → γt) = 1.35±0.11. (orig.)

  8. Measurement of polarization of {sup 3}He with mobile polarized {sup 3}He neutron spin filter

    Ino, T. [Neutron Science Laboratory, Institute of Materials Structure Science, KEK, High Energy Accelerator Research Organization, Ibaraki-ken 305-0801 (Japan); Kim, G.N., E-mail: gnkim@knu.ac.kr [Department of Physics, Kyungpook National University, Daehak-ro 80, Buk-gu, Daegu 702-701 (Korea, Republic of); Lee, M.W. [Department of Physics, Kyungpook National University, Daehak-ro 80, Buk-gu, Daegu 702-701 (Korea, Republic of); Lee, S.M. [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Kim, J.Y. [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-353 (Korea, Republic of); Lee, S.W. [School of Mechanical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Skoy, V.R. [Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-03-15

    A mobile polarized {sup 3}He neutron spin filter was developed for both optical pumping and transportation, and the polarization of {sup 3}He was measured with cold neutrons of HANARO in KAERI. The progress of polarization build-up during the optical pumping of the {sup 3}He cell was observed by adiabatic fast-passage NMR system. The {sup 3}He cell was made of an alumino-silicate glass GE-180 with a cylindrical shape of 40 mm in diameter and 60 mm in length from KEK. A cell contained 5.74 bar⋅cm of {sup 3}He gas. The whole installation after 8 h pumping was transported to the general-purpose test station of the HANARO research reactor and the polarization of {sup 3}He was measured with cold neutrons. The measured polarization of {sup 3}He was 0.18 ± 0.01 by measuring the neutron transmission through the {sup 3}He cell.

  9. Spin dynamics of 3He in aerogel

    The authors report continuous-wave NMR measurements on superfluid 3He contained inside high porosity aerogel at 3.24 MPa, in a 28.4 mT magnetic field, and down to 0.9 mK. Three different purities of 3He were used: pure 3He, 3He with enough 4He to replace the first localized layer, and 3He with enough 4He to replace both localized layers. Below 2.26mK, the NMR spectrum does not consist of a single Lorentzian, but a distribution of NR resonant frequencies both above and below the Larmor frequency, ωL. Upon cooling, the component of the spectrum at frequencies below the Larmor frequency moves to higher frequencies over a narrow temperature range and does not return to ω L upon warming. The higher frequency component of the spectrum displays two resolvable peaks which become a complex structure upon removal of the localized 3He spins. The spectrum changes as the magnetic field is rotated about the axis of the aerogel sample, indicating that the 3He is able to detect a preferred direction in the aerogel. The shape of the spectrum shows no rotation or magnetic field hysteresis. The authors find that the average frequency shifts of the NMR spectra do not depend on the presence of the localized 3He spins. These frequency shifts and the presence of a temperature-independent magnetization for the liquid 3He suggest that the aerogel stabilizes a single equal-spin-pairing state in the experiments

  10. Towards the study of 2H(p, γ)3He reaction in the Big Bang Nucleosynthesis energy range in LUNA

    Kochanek, Izabela

    2016-04-01

    The Big Bang Nucleosynthesis began a few minutes after the Big Bang, when the Universe was sufficiently cold to allow deuterium nuclei to survive photo-disintegration. The total amount of deuterium produced in the Universe during the first minutes depends on the cosmological parameters (like the energy density in baryons, Ω bh 2, and the effective neutrino number, Neff ) and on the nuclear cross sections of the relevant reactions. The main source of uncertainty in the deuterium estimation comes from the 2H(p, γ)3He cross section. Measurements of Cosmic Microwave Background (CMB) anisotropies obtained by the Planck satellite are in very good agreement with the theoretical predictions of the minimal ΛCDM cosmological model, significantly reducing the uncertainty on its parameters. The Planck data allows to indirectly deduce with very high precision the abundances of primodial nuclides, such as the primodial deuterium fraction 2H/H = (2.65 ± 0.07) .10-5 (68% C.L.). The astrophysical observations in damped Lyman-a systems at high redshifts provide a second high accuracy measurement of the primodial abundance of deuterium 2H/H = (2.53 ± 0.04) · 10-5 (68% C.L.). The present experimental status on the astrophysical S-factor of the 2H(p, γ)3He reaction in the BBN energy range, gives a systematic uncertainties of 9%. Also the difference between ab-initio calculations and experimental values of S12 is at the level of 10%. In order to clarify the actual scenario, a measurement of 2H(p, γ)3He cross section with a precision of a few percent in the 70-400 keV energy range is planned at LUNA in 2016. A feasibility test of the measurement has been performed in October 2014, giving the preliminary results on the cross section. The experimental setup for the test and final measurement campaign will be presented.

  11. 3He melting pressure temperature scale

    Halperin, W.P.; Archie, C.N.; Richardson, R.C.;

    1976-01-01

    The latent heat for solidification of **3He has been measured along the **3He melting curve between 23 and 1 mK. A temperature scale is established which depends only on measurements of heat, pressure and volume, and on the condition that the entropy of solid **3He approaches R ln 2 at high...... temperatures. The A feature of the melting curve which suggests itself as a thermometric fixed point is found to be T//A equals 2. 75 plus or minus 0. 11 mK. The agreement between this value and independent measurements of T//A, based on nuclear or electronic paramagnetism, Johnson noise thermometry...

  12. Photodisintegration of 3H and 3He

    The photoneutron cross sections for 3H and 3He 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 3H and the three-body breakup of both 3H and 3He; these measurements for 3H are the first to span the energy region across the peaks of the cross sections. An efficient BF3-tube-and-paraffin neutron detector and high-pressure gaseous samples of several moles each (the activity of the 3H sample was approx. 200,000 Ci) were employed in these measurements. Measurements on 16O and 2H 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 3He from the literature, show that the two-body breakup cross sections for 3H and 3He have nearly the same shape, but the one for 3He lies lower in magnitude; the three-body breakup cross section for 3He lies higher in magnitude and is broader in the peak region and also rises less sharply from threshold than that for 3H; 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 3H and 3He 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

  13. Heat capacity of 3He in aerogel

    The heat capacity of pure 3He in low density aerogel is measured at 22.5 bars. The superfluid response is simultaneously monitored with a torsional oscillator. A slightly rounded heat capacity peak, 65 μK in width, is observed at the 3He-aerogel superfluid transition, Tca. Subtracting the bulk 3He contribution, the heat capacity shows a Fermi-liquid form above Tca. We can fit the heat capacity attributed to superfluid within the aerogel with a rounded BCS form accounting for 0.30 of the nonbulk fluid in the aerogel, or by assuming a substantial reduction in the superfluid order parameter. Both approaches are consistent with earlier superfluid density measurements

  14. Quantum prewetting transitions in liquid 3He

    Multilayer 3He film growth on weak-binding alkali substrates is investigated with a non-local density functional theory. Although 3He wets all substrates, prewetting transitions are predicted to occur on cesium and potassium. Emphasis is put on the role played by the Fermi statistics. Prewetting critical temperatures are estimated. Continuous wetting at zero temperature is recovered with increasing strength of substrate potential. The heat capacity and the magnetization of the films exhibits steps associated with the occupation of two-dimensional (2D) Fermi discs. (authors). 24 refs., 4 figs

  15. 3He-4He II mixtures

    A theoretical study of the thermodynamic and hydrodynamic properties of 3He-4He II mixtures at temperatures below 250 mK is described. A hydrodynamic model is set up which incorporates mutual friction between the two components. Results of an investigation into the quantitative calculation of the mutual friction are reported. 148 refs.; 34 figs.; 4 tabs

  16. NMR experiments on pure 3He and 3He-4He mixtures in silica aerogel

    We have carried out a series of NMR experiments on 4He systems filling the pores of silica aerogel with 95% porosity. The systems studied included 3He-4He mixtures with a wide range of 3He concentrations x3 as well as pure 3He. All experiments were conducted in an 8 T field and for temperatures T ≥ 6 mK. This resulted in strong spin polarization at the lowest temperatures (up to approximately 80%) for the localized layer observed for a pure 3He sample. For pure 3He, the magnetic behavior is dominated by the localized spins, which are found to constitute 6% of the sample. The coupled system of localized plus liquid spins displays rapid transverse magnetization relaxation with an anomalous temperature dependence. For intermediate x3 magnetization measurements provide a preliminary indication of the phase diagram of mixtures filling this porous material. The magnetization is hysteretic over some ranges of x3

  17. 3He Spin Filter for Neutrons

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

    2005-01-01

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

  18. X-rays from pionic 3He

    Pionic X-ray energies, lorentzian widths, and relative intensities have been measured for the transitions in liquid 3He. The pion-nucleus interaction is found to result in an attractive shift of the 1s level of 27 +- 5 eV and in a lorentzian width of 65 +- 12 eV. The measured Ksub(β) to Ksub(α) intensity ratio is 1.05 +- 0.07. (Auth.)

  19. Size effects in superfluid 3He

    The superfluid density and transition temperature of 3He filling the pores of packed alumina powder have been measured by fourth sound. The measurements were performed simultaneously for three separate fourth sound resonators, each packed with a different nominal grain size of 1.0 μm. 0.3 μm and 0.05 μm. The bulk 3He superfluid transition temperature, which was determined independently, was compared to the transition temperature of each resonator. We observed a systematic depression for both the superfluid density and transition temperature as the powder size was decreased. The depressions in the transition temperature were compared with theoretical estimates of size dependent transition temperatures for the ideal geometry of an infinite cylinder. In the analysis the cylinder radius was replaced by defining an average radius of the pore structure which was empirically determined by nitrogen gas sorption and mercury intrusion techniques. The pressure dependence of the transition temperature depression is found to be consistent with theoretical estimates of the superfluid coherence length. The experimentally determined magnitude of the coherence length based on the pore structure analysis is in agreement with theoretical estimates, confirming that the coherence length of superfluid 3He is about two orders of magnitude larger than that of He II

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

    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

  1. Pion absorption in flight on 3He

    Pion absorption in flight on 3He has been measured in a kinematically complete manner. The experiment was done in the πE1-channel at the Swiss Institute for Nuclear Research, SIN, using π+- and π--beams of 120 and 165 MeV kinetic energy. Two of the emitted particles were measured in coincidence and identified by their time-of-flight/pulseheight relation. The obtained two-dimensional energy representation enabled a separation of the different kinematical regions and exhibited a clear enhancement in the region of quasifree absorption, QFA. (orig./WL)

  2. 3He and 4f instable compounds

    The high localization of the 4f electron and the possibility of a weak delocalization through the coupling with the itinerant electrons lead to Fermi liquid properties. With the example of CeAl3, the main role of the coherence between the Ce is emphasized at low temperature. Thermal dilatation data show the transition from a regime of almost independent Kondo centers to a regime of coherent Kondo centers. The occurence of the superconductivity in the heavy fermion CeCu2Si2 is discussed and compared to the superfluidity of liquid 3He

  3. Duoplasmatron source modifications for 3He+ operation

    A duoplasmatron ion source is used to produce 25 mA of 3He+ with a pulse width of ∼80ms 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

  4. A density functional for liquid 3He

    We present a density functional for the description of liquid 3He properties at zero temperture in a mean field approximation. Its basic ingredients are a zero-range, particle- and spin-density dependent effective interaction of Skyrme type, and a long-range effective interaction of Lennard-Jones type supplemented with a weighted density approximation similar to the one used in the study of classical fluids, to phenomenologically account for short range correlations. After fixing the value of its parameters, the functional yields a good desription of the equation of state and Landau parameters (spin symmetric and spin antisymmetric as well) from saturation to solidification densities. The zero sound propagation at finite momentum transfer is quantitatively reproduced up to the Fermi momentum, and qualitatively above it. The surface tension is in agreement with experiment, which makes the functional well suited for 3He drop calculations. We describe the structure of drops made of up to 516 atoms. As a novel application, we discuss the possible appearance of triplet pairing in a nl-shell of a drop applying the formalism to the 1j-shell holding up to 30 atoms from N=169 to 198. (orig.)

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

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

    2015-03-01

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

  6. Hyperpolarized 3He MRI and 81mKr SPECT in chronic obstructive pulmonary disease

    Stavngaard, Trine; Søgaard, Lise; Mortensen, J;

    2005-01-01

    compare ventilation imaging methods in 26 patients with chronic obstructive pulmonary disease (COPD) and nine lung healthy volunteers. METHODS: HP 3He MRI, 81mKr single-photon emission computed tomography (SPECT), high-resolution computed tomography (HRCT) and pulmonary function tests were performed. The...... visual defect score (r=0.80, p<0.0001) and objective estimate of ventilation (r=0.45, p=0.0157). In addition, both scanswere well correlated with reference methods for the diagnosis of emphysema (pulmonary function test and HRCT). The defect scores were largest on 81mKr SPECT (the score on HP 3He MRI was...... defect scores are comparable on HP 3He MRI and 81mKr SPECT. Additionally, new insights into the regional pulmonary microstructure via the apparent diffusion coefficient measurements are provided by HP 3He MRI. HP 3He MRI is a promising new diagnostic tool for the assessment of ventilation distribution...

  7. Simultaneous measurement of pulmonary partial pressure of oxygen and apparent diffusion coefficient by hyperpolarized 3He MRI

    Yu, Jiangsheng; Law, Michelle; Kadlecek, Stephen; Emami, Kiarash; Ishii, Masaru; Stephen, Michael; Woodburn, John M.; Vahdat, Vahid; Rizi, Rahim R.

    2009-01-01

    Hyperpolarized 3He (HP 3He) MRI shows promise to assess structural and functional pulmonary parameters in a sensitive, regional and non-invasive way. Structural HP 3He MRI has applied the apparent diffusion coefficient (ADC) for the detection of disease-induced lung microstructure changes at the alveolar level, and HP 3He pulmonary partial pressure of oxygen (pO2) imaging measures the oxygen transfer efficiency between the lung and blood stream. Although both parameters are affected in chroni...

  8. Low temperature adsorption of 3He on silica aerogel surface and its influence on 3He spin kinetics

    Significant influence of the aerogel surface heterogeneity on the processes of 3He nuclear magnetic relaxation at temperatures 1.5 − 4.2 K is discovered. This influence appears, for instance, in differences of the 3He T1 relaxation times for small portion of 3He, adsorbed at different temperatures. Binding energy data of 3He and distributions of this energy in two types of aerogel were obtained experimentally. Adsorbed 3He molecules with binding energies 60 – 250 K play supreme role in processes of nuclear magnetic relaxation of gaseous and liquid 3He in aerogel.

  9. Hyperpolarised 3He MRI and 81mKr SPECT in chronic obstructive pulmonary disease

    During recent years, magnetic resonance imaging (MRI) using hyperpolarised (HP) 3He gas has emerged as a promising new method for the imaging of lung ventilation. However, systematic comparisons with nuclear medicine techniques have not yet been performed. The aim of this study was to compare ventilation imaging methods in 26 patients with chronic obstructive pulmonary disease (COPD) and nine lung healthy volunteers. HP 3He MRI, 81mKr single-photon emission computed tomography (SPECT), high-resolution computed tomography (HRCT) and pulmonary function tests were performed. The three scans were scored visually as percentage of non-ventilated/diseased lung, and a computer-based objective measure of the ventilated volume in HP 3He MRI and 81mKr SPECT and an emphysema index in HRCT were calculated. We found a good correlation between HP 3He MRI and 81mKr SPECT for both visual defect score (r=0.80, p81mKr SPECT (the score on HP 3He MRI was one-third less than that on 81mKr SPECT), but the difference was reduced after normalisation for different breathing depths (HP 3He MRI at total lung capacity; 81mKr SPECT at tidal breathing at functional residual capacity). HP 3He MRI provides detailed ventilation distribution images and defect scores are comparable on HP 3He MRI and 81mKr SPECT. Additionally, new insights into the regional pulmonary microstructure via the apparent diffusion coefficient measurements are provided by HP 3He MRI. HP 3He MRI is a promising new diagnostic tool for the assessment of ventilation distribution. (orig.)

  10. Critical opalescent light scattering from 3He

    The experimental work reported in this paper was stimulated by the widespread revival of interest in critical phenomena. In this experiment the authors measured the intensity of light scattered from 3He while very slowly warming the sample at constant pressure through the critical region. About 0.3 mW from a helium-neon laser was incident on the cell; cell temperature was recorded continuously, as was the light scattered at 45 degrees and 135 degrees. A succession of passes was made at different pressures, all less than c, so these results apply only in the one-phase region above the critical point. Sample density at the beginning of a pass began at ρ > c, then decreased as the sample warmed to ρ c. The scattering intensity increased monotonically as the molar density decreased toward the critical density, then decreased monotonically thereafter on that isobaric pass. The scattering maximum on each pass occurred at the temperature max where the isothermal compressibility was a maximum. The asymptotic divergence of T was evaluated along the locus of these maxima

  11. Possibility of optically pumped 3He as an internal target

    A number of techniques can be listed for obtaining polarized 3He nuclei. This paper focuses only on direct optical pumping of 3He(3S1) with collisional transfer to 3He. A comprehensive review is not attempted. The basic aspects of the method are presented followed by a discussion of only the most recent work

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

    Kamensky, I.L.; Tolstikhin, I.N. (Kola Science Center (Russian Federation)); Tokarev, I.V. (Leningrad Mining Inst., St. Petersburg (Russian Federation))

    1991-10-01

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

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

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

  14. Acoustic and optical investigations of superfluid 3He. Doctoral thesis

    Manninen, A.

    1993-06-15

    The thesis is an experimental survey of properties of rotating and stationary superfluid (3)He. Two techniques, acoustics and optics, were used. Ultrasound, together with NMR, has provided most of the present experimental knowledge about the superfluid phases of (3)He. The author applied acoustics for the first time to study rotating (3)He. The main result was the discovery of a new vortex in (3)He-A when the magnetic field is low. New phenomena were observed in stationary (3)He as well. Most importantly, one of the collective modes, the real squashing (rsq) mode, of (3)He-B could be excited by means of two-phonon absorption. Superfluid (3)He was studied optically for the first time. No one has previously seen (3)He in the superfluid state. The principal achievement was developing techniques which facilitate optical experiments at temperatures below 1 mK, required to study superfluid (3)He. Optical fibers were used to transmit light between room temperature and the cold parts of the cryostat. Before these investigations, photography had not been done below 10 mK. The usefulness of optics as a proble of the superfluid phases of (3)He was demonstrated by studying the macroscopic shape of the free surface of rotating (3)He-B. The classical parabolic meniscus was observed, which is indicative of the equilibrium density of vortices.

  15. 3He charge form factors by nuclear recoil detection

    3He charge form factors were measured by observing the scattering reaction 3He(e,3He)e from square momentum transfers 0.885 to 3.20 fm-2. The results compare favorably with earlier electron scattering experiments. A model-independent determination of the radial charge density gives an rms radius of 1.877 +- 0.019 fm, in excellent agreement with previous radii determinations

  16. Polarization phenomena for low energy d + 3He collisions

    Polarization phenomena are studied for the reaction d + 3He → p + 4He (for Ed ≤ 1 MeV) using a formalism of partial amplitudes. The nuclei are considered as elementary particles with definite values of spin and P-parity. A general parametrization of the matrix element in terms of a limited number of partial amplitudes (for d + 3He-interaction in s - and p- states) is given and the expressions for all polarization observables are derived for the s-interaction. Relations between different polarization observables are derived and the conditions for maximizing the differential cross section of the process d + 3He → p + 4He are indicated. The spin structure of the matrix elements of the processes d + 3He → d +3He, d + 3He → n +p + 3He, d + 3He → p + p + 3H and d + 3He → d + d + p is established in the near-threshold region. (author)

  17. Measurements of the 3He fusion product in TFTR

    The 0.8-MeV 3He ion created in the d(d,n)3He fusion reaction is confined in TFTR and can undergo d(3He,p)α fusion reactions. The time evolution, and profile of the 14.7-MeV proton emission indicates that collisional energy transfer with plasma electrons is the dominant process influencing the charged 3He fusion product for TFTR plasmas and that there is no observable anomalous transport. The magnitude of the burnup exceeds classical expectations by a factor-of-two-to-three which is a little beyond experimental uncertainties. 19 refs., 11 figs

  18. 3He Neutron Spin Filter cell development program at JCNS

    In order to produce high-quality 3He Neutron Spin Filters (NSF) with a high polarisation level, it is necessary to achieve a long 3He relaxation time by the reduction of the wall relaxation. This requires one to minimise the amount of impurities at the surface of the glass cells, and to have as few contaminants as possible in the gas filling system. In this report we describe the detailed procedure we employ to produce 3He cells using our newly built filling station. The obtained life times for a number of cells are practically approaching the fundamental limit imposed by the dipole-dipole interaction between 3He atoms.

  19. 3He functions in tokamak-pumped laser systems

    3He placed in an annular cell around a tokamak fusion generator can convert moderated fusion neutrons to energetic ions by the 3He(n,p)T reaction, and thereby excite gaseous lasants mixed with the 3He while simultaneously breeding tritium. The total 3He 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

  20. Three-body 3He photodisintegration in the Δ region

    Three-body 3He photodisintegration was measured in the photon energy range (Eγ) of 145--425 MeV. The total cross section for photon absorption on the np pairs in 3He, σ(3He(γ,np)psp), where psp is a spectator proton, is reported here for the first time. The Eγ dependence of the σ is found to scale to that of σ(2H(γ,np)), and the ratio is determined to be σ(3He(γ,np)psp)/σ(2H(γ,np))=1.24±0.,26

  1. Model formalism of liquid 3He-B at equilibrium

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

  2. 3He(3H,γ)6Li

    The authors have calculated the 3He(3H,γ)6Li reaction rate at big bang temperatures based on a microscopic study in the framework of the Generator Coordinate Method. It is discussed whether 6Li could be made by 3He + 3H fusion in the early epoch of our universe

  3. Some new NMR effects in superfluid 3He--A

    Longitudinal and transverse satellite lines have been observed by CW techniques in superfluid 3He-A under a variety of experimental conditions. A new metastable mode has been observed in superfluid 3He-A using pulsed NMR techniques. The frequency shift of this mode is related to the frequency shift of the transverse satellite line

  4. magnetic resonance of 3He nuclei in porous media

    The data on 3He spin kinetics in porous media above the Fermi temperature of 3He are summarized. Presented results are obtained in Kazan Federal University in last ten years and are the base of developing method of helium porometry. Guidelines for investigation of samples with unknown pore sizes and superficial their properties are proposed

  5. Ions Preheated in 3He-Rich Solar Particle Events

    王德焴

    2003-01-01

    A wave-particle resonance absorption model in the two-ion plasma is suggested in explanation to the coronal ions preheating in 3He-rich solar particle events. It is found that 3He and Fe ions are preferably preheated by the ion-ion hybrid waves at their fundamental and second harmonic ion cyclotron frequencies, respectively.

  6. Pulsed NMR experiments in superfluid 3He confined in aerogel

    Pulsed NMR experiments have been performed in both B and supercooled A phases of superfluid 3He in aerogel. Dependencies of spin precession frequency on tipping angle in B-phase of superfluid 3He in aerogel are found to be different for pure 3He and for the cell preplated with 4He. A sharp increase of the frequency for tipping angles greater than 104 deg. was observed in low temperature superfluid phase of 3He in 4He preplated aerogel as it is expected for the B-phase structure of the order parameter. Dependencies of the frequency on the tipping angle in supercooled A-phase are similar for both pure 3He and 4He preplated aerogel

  7. Feasibility studies of D—3He fusion power in China

    DengBai-Quan; FengKei-Ming; 等

    1997-01-01

    The systematic study on D-3He advanced fuel fusion in China has been performed.Comparisons between D-3He and D-T fuel cycles in physics,engineering,environmental safety and so on have been made.D-3He fusion offers significant adavantages for reducing the neutron yield by a factor of 10-60,The 3He resource and mining possibility are investigated.The energy payback factor of 97 for mining lunar 3He resource is calculated.The operating parameter scope for D-3He fueled Tokamak reactor is analyzed.The prompt energy broadening for fusion products is calculated and results are consistent with those obtained by Lehner using a different method.Centrally peaked current drive with high efficiency is studied utilizing plasma synchrotron radiation.Centrally peaked current drive with gigh efficiency is studied utilizing plasma synchrotron radiation.More than 80% of plasma current required can be driven passively.A D-3He fueled Tokamak commercial reactor-Mooncity was designed.Neutronics calculations show that the radioactivity,afterheat,BHP value for Mooncity are 10-60 times less than those for D-T fusion.

  8. Cosmogenic and nucleogenic ^3He in apatite, titanite, and zircon

    Farley, K. A.; Libarkin, J.; Mukhopadhyay, S; Amidon, W.

    2006-01-01

    Cosmogenic ^3He was measured in apatite, titanite, and zircon and cosmogenic ^(21)Ne in quartz at 13 depth intervals in a 2.7-m long drill core in a Miocene ignimbrite from the Altiplano of Bolivia. All three ^3He depth profiles as well as the ^(21)Ne profile attenuate exponentially with depth, indicating that both of these isotopes are cosmogenic in origin with no significant contribution from other sources. The attenuation lengthscale for ^3He production of Λ = 180 ± 11 g/cm^2 is consistent...

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

    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

  10. Dressed Spin of Polarized 3He in a Cell

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

    2010-01-01

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

  11. Safeguards Technology Factsheet 3He-free Neutron Coincidence Counter

    A full scale thermal neutron coincidence counter (High Level Neutron Counter - Boron: HLNB) based on 3He alternative detection technology was designed and built at LANL and field tested at Plutonium Conversion Development Facility (PCDF) of Japan Atomic Energy Agency (JAEA) during FY15. HLNB is based on boron-lined proportional plates that replace the traditional 3He proportional tubes and was designed as a direct alternative to 3He-based High Level Neutron Coincidence Counter (HLNC-II). During the JAEA field trial the HLNB demonstrated comparable performance to HLNC-II, which represents a key development in the area of 3He alternative technologies and provides a complete demonstration of the technology for nuclear safeguards applications including high mass MOX samples.

  12. Magnetization and spin diffusion of liquid 3He in aerogel

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

  13. Applications of 3He neutron spin filters at the NCNR

    At the NIST Center for Neutron Research (NCNR), we have applied 3He neutron spin filters (NSFs) to the instruments where 3He NSFs are advantageous, such as thermal triple-axis spectrometry, small-angle neutron scattering, and diffuse reflectometry. We present the status of our development and application of this method, including polarized gas production by spin-exchange optical pumping, magnetostatic cavities for storage of the polarized gas on the beam line, and nuclear magnetic resonance (NMR)-based, on-line monitoring and reversal of the 3He polarization. We present the status of developing user-friendly interfaces incorporated into the instrument software to handle these 3He neutron spin filters while taking data and performing data analysis. Finally we discuss the status of development of a polarization capability on the multi-axis crystal spectrometer, which requires polarization analysis over a 220 deg. angular range.

  14. Electromagnetic physics with a polarized 3He target

    In the trinucleon system, 3He is preferable for polarization measurements because it is stable and a well-understood polarization method exists. Also, to a good approximation, the 3He spin is effectively due to the spin of its neutron and hence acts as a polarized neutron target. This is important because dense targets of polarized free neutrons are not possible. Thus, in a simple-minded picture, one can think of polarization measurements on 3He as a means of tagging the neutron in this nucleus. In a general program of polarization measurements on the proton, deuteron, and 3He, one could investigate the form-factors and small wave-function components of the nucleon and its excited states in the nuclear medium. (orig./WL)

  15. The SLAC high-density gaseous polarized 3He target

    A large-scale high-pressure gaseous 3He 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 7 x1021 nuclei/cm2 and operated at 3He polarizations between about 30% and 40% for the six-week duration of the experiment

  16. Neutron orbital structure from generalized parton distributions of 3He

    Rinaldi, M; Scopetta, S.

    2012-01-01

    The generalized parton distribution H and E of the 3He nucleus, which could be measured in hard exclusive processes, such as coherent deeply virtual Compton scattering, are thoroughly analyzed in impulse approximation, within the Av18 interaction. It is found that their sum is dominated to a large extent by the neutron contribution: The peculiar spin structure of 3He makes this target unique for the extraction of the neutron information. This observation could allow to access for the first ti...

  17. Extracting generalized neutron parton distributions from 3He data

    Rinaldi, M; Scopetta, S.

    2012-01-01

    An impulse approximation analysis is described of the generalized parton distributions (GPDs) H and E of the 3He nucleus, quantities which are accessible in hard exclusive processes, such as coherent deeply virtual Compton scattering (DVCS). The calculation is based on the Av18 interaction. The electromagnetic form factors are correctly recovered in the proper limits. The sum of the GPDs H and E of 3He, at low momentum transfer, is largely dominated by the neutron contribution, thanks to the ...

  18. Analytic vortices in rotating superfluid 3He-A

    Recent works on analytic vortices in rotating 3He-A are reviewed. It is shown that the circular-hyperbolic vortex lattice has the lowest free energy in an axial magnetic field. The associated nuclear magnetic resonance satellites account for not only the observed satellite frequencies in a rotating 3He-A experiment but also the observed intensity of the satellite resonances. 15 references, 3 figures

  19. Elastic and charge exchange scattering of pions from 3He

    Elastic and charge exchange scatterings of pions from 3He are studied using on optical potential in the momentum representation, which includes the second order effect as well as the nucleon binding correction. These corrections are found to be appreaciable but still not enough to resolve the discrepancy between theoretical calculations and recent experimental data on the reaction 3He(π-, π0)3H. (author)

  20. The 3He spectral function in light-front dynamics

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

    2016-01-01

    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 Poincar\\'e covariant framework within the light-front dynamics is outlined.

  1. Test of 3He-based neutron polarizers at NIST

    Neutron spin filters based on polarized 3He 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 3He 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

  2. Electroproduction of low energy π+ from 3He

    Differential cross sections were measured for the electro-pion production from H and 3He at an incident energy of 200 MeV and pion energies from 7.3 to 12.1 MeV. Pion-angular distributions are presented and compared with theory. For hydrogen there is good agreement. A simple three-channel calculation performed for the pion production from 3He was found to over estimate the cross section at forward pion angles

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

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

    2015-10-16

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

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

    In order to investigate the 3He-n-p system as a three-body problem, we have formulated 3He-n and 3H-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 3He-n, 3H-p, and 3He-p phase shifts. Therefore, they describe the 3He-n differential cross section, the polarization observables, and the energy levels of 4He. The 3He-n-p Faddeev equations are solved numerically. We reproduce correctly the ground state and the first excited state of 5Li. Furthermore, the Paris-type potential is used to investigate the 3He(d,p)4He 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.)

  5. The (t,3He) and (3He,t) reactions as probes of Gamow-Teller strength

    Zegers, R G T; Austin, S M; Bazin, D; Berg, G P A; Brown, B A; Cole, A L; Daito, I; Fujita, Y; Fujiwara, M; Galès, Sydney; Harakeh, M N; Hashimoto, H; Hayami, R; Hitt, G W; Howard, M E; Itoh, M; Jänecke, J; Kawabata, T; Kawase, K; Kinoshita, M; Nakamura, T; Nakanishi, K; Nakayama, S; Okamura, S; Richter, W A; Roberts, D A; Sherrill, B M; Shimbara, Y; Steiner, M; Uchida, M; Ueno, H; Van den Berg, A M; Yamagata, T; Yosoi, M; Austin, Sam M.

    2006-01-01

    Charge-exchange reactions are an important tool for determining weak-interaction rates. They provide stringent tests for nuclear structure models necessary for modeling astrophysical environments such as neutron stars and core-collapse supernovae. In this paper we demonstrate via a study of 26Mg(t,3He) that the (t,3He) reaction at 115 MeV/nucleon is an accurate probe for extracting Gamow-Teller strengths. This study is complemented by 26Mg(3He,t) data taken at 140 MeV/nucleon which allows for a comparison of T=2 analog states excited via the mirror reactions. A good correspondence is found between Gamow-Teller distributions measured via the 26Mg(3He,t) and 26Mg(p,n) experiments, indicating probe-independence of the strength extraction. Results from 26Mg(t,3He) and 26Mg(d,2He) also display good correspondence, showing that with the (t,3He) reaction a new tool has become available for studying Gamow-Teller strengths in the beta+ direction. Furthermore, we test shell-model calculations using the new USD-05B inte...

  6. Experimental Search for μd 3He Fusion

    The vast majority of muon catalyzed fusion research has been concerned with muonic molecules of hydrogen isotopes only, since the dynamics of higher-Z muonic atoms in general preclude the formation of molecular systems. In the specific case of hydrogen-helium mixtures, bound muonic molecular states can exist, and thus it is possible to search for the reactionμd 3Heλ-tilde fμ+α(3.66 MeV)+p(14.64 MeV).Until recently, the theoretical predictions for the nuclear fusion rate in the μd 3He molecule, λ-tildef, ranged over one order of magnitude, from 105 to 106 per second. An experimental upper limit has been measured for λ-tildef in HD + 3He giving a value (4 s-1 [1]). We report on the analysis of an experiment in D2 + 3He which has shown a signal coming either from the muon catalyzed reaction, or from the fusion in flight of 3He's formed from dμd fusion.

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

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

    2008-01-01

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

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

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

    2008-10-01

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

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

    We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g1 of the neutron and 3He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)2. Global duality is observed for the spin-structure function g1 down to at least Q2=1.8 (GeV/c)2 in both targets. We have also formed the photon-nucleon asymmetry A1 in the resonance region for 3He and found no strong Q2 dependence above 2.2 (GeV/c)2

  10. 3He Neutron Detector Pressure Effect and Comparison to Models

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

  11. Light-Front Dynamics and the 3He Spectral Function

    Pace, Emanuele; Kaptari, Leonid; Rinaldi, Matteo; Salme', Giovanni; Scopetta, Sergio

    2016-01-01

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

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

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

    2014-11-01

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

  13. Asymmetries in electron-induced breakup of polarized 3He

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

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

    Nikiel, A; Heil, W; Hehn, M; Karpuk, S; Maul, A; Otten, E; Schreiber, L M; Terekhov, M

    2014-01-01

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

  15. Neutron orbital structure from generalized parton distributions of 3He

    Rinaldi, M

    2012-01-01

    The generalized parton distribution H and E of the 3He nucleus, which could be measured in hard exclusive processes, such as coherent deeply virtual Compton scattering, are thoroughly analyzed in impulse approximation, within the Av18 interaction. It is found that their sum is dominated to a large extent by the neutron contribution: The peculiar spin structure of 3He makes this target unique for the extraction of the neutron information. This observation could allow to access for the first time, in dedicated experiments, the orbital angular momentum of the partons in the neutron.

  16. Neutron orbital structure from generalized parton distributions of 3He

    Rinaldi, M.; Scopetta, S.

    2012-06-01

    The generalized parton distribution H and E of the 3He nucleus, which can be measured in hard exclusive processes such as coherent deeply virtual Compton scattering, are thoroughly analyzed in impulse approximation, within the Av18 interaction. It is found that their sum, at low momentum transfer, is dominated to a large extent by the neutron contribution: the peculiar spin structure of 3He makes this target unique for the extraction of the neutron information. This observation allows access, in dedicated experiments, to the orbital angular momentum of the partons in the neutron.

  17. Removing gaseous contaminants in 3He by cryogenic stripping

    The Tritium Operations Group at LLNL, Tritium Facility has recently developed a 3He recovery system to remove argon, xenon, neon, hydrogen, and all other contaminants from the 3He 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

  18. Rotational quenching of CS in ultracold 3He collisions

    Kaur, Rajwant; Dhilip Kumar, T. J.

    2016-08-01

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

  19. A measurement of the Panofsky ratio in 3He

    The nucleus 3He is one of the simplest nuclear systems; hence it is often used to study the complications introduced by the presence of additional nucleons on basic processes such as pion absorption on a free nucleon. 3He is the only nucleus for which both the pion charge exchange and radiative capture processes can occur at rest with reasonable probability. The ratio of these two processes is the well-known Panofsky ratio, P3 = ω(π-3He→π0T)/ω(π-+3He→γT). (orig./WL)

  20. 3H and 3He electromagnetic form factors

    We report the results of three experiments on elastic electron scattering from 3H and 3He. A detailed description of the experiments and the data obtained is given. We have performed a combined analysis of the world data on 3H and 3He. This analysis gives a complete experimental information on the trinucleon electromagnetic form factors up to q2=30 fm-2, and also provides a separation into the isoscalar and isovector form factors. The results are compared to selected calculations that include nucleonic and mesonic degrees of freedom. ((orig.))

  1. Transport properties of spin polarized 3He-4He mixtures

    We have calculated the viscosity, thermal conductivity, and longitudinal spin diffusion coefficient in 3He-4He mixtures which are spin polarized. The calculation applies to all temperature regimes. We have also calculated the Onsager cross coefficient which arises because of the coupling between heat and longitudinal spin currents. The interaction between 3He quasiparticles is taken to be a constant as a first approximation. We have also investigated the changes brought about by allowing the interaction to vary with the momentum of the quasiparticle

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

    Nikiel, A.; Blümler, P.; Heil, W.; Hehn, M.; Karpuk, S.; Maul, A.; Otten, E.; Schreiber, L. M.; Terekhov, M.

    2014-01-01

    We describe a 3He magnetometer capable to measure high magnetic fields (B > 0.1 Tesla) with a relative accuracy of better than 10^-12. Our approach is based on the measurement of the free induction decay of gaseous, nuclear spin polarized 3He following a resonant radio frequency pulse excitation. The measurement sensitivity can be attributed to the long coherent spin precession time T2* being of order minutes which is achieved for spherical sample cells in the regime of motional narrowing whe...

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

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

    2016-06-01

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

  4. An internal polarized 3He target for electron storage rings

    We describe an internal polarized 3He target currently under construction which will be used in several electron storage ring experiments. The target is based on the technique of metastability exchange laser optical pumping, where the polarized atoms flow into a cryogenically-cooled storage cell. This novel technique allows for high precision measurements where the beam interacts with the pure atomic species. Both the HERMES experiment at DESY and the BLAST detector at the MIT Bates Laboratory will use the polarized 3He target in their measurements. Details of the target system, including the provisions needed to incorporate the target into the electron storage ring, are presented. (orig.)

  5. NMR experiments on rotating superfluid 3He-A and 3He-B and their theoretical interpretation

    We have constructed a rotating nuclear demagnetization cryostat and used it for continuous-wave NMR experiments on superfluid 3He-A and 3He-B. The measurements were performed in a long cylindrical geometry of 5 mm diameter, with the cylinder axis parallel to the axis of rotation and with the external magnetic field H/sub O/ = 284 or 142 Oe in the same direction. The angular velocity of rotation Ω was varied between 0.2 and 1.5 rad/sec, and the experiments were done under 29.3 bar pressure at temperatures between T/sub c/ = 2.72 and about 1.4 mK. As a guide to the new and esoteric field of superfluid 3He in rotation, we first review the general theory at some length in relatively simple terms. Pictorial explanations are often given

  6. The design of the 3He readout system on CSNS

    Used in the High-Intensity Powder Diffraction in China Spallation Neutron Sources (CSNS) Project, the electronic parts of the 3He readout system is introduced. The design of the Charge Measurement module (MQ) is described in details, including the structure of the circuit, the firmware of the FPGA on the board. The test results are given out in the final. (authors)

  7. Extracting neutron generalized parton distributions from 3He data

    Rinaldi, M

    2012-01-01

    An impulse approximation analysis is described of the generalized parton distributions (GPDs) H and E of the 3He nucleus, quantities which are accessible in hard exclusive processes, such as coherent deeply virtual Compton scattering (DVCS). The calculation is based on the Av18 interaction. The electromagnetic form factors are correctly recovered in the proper limits. The sum of the GPDs H and E of 3He, at low momentum transfer, is largely dominated by the neutron contribution, thanks to the unique spin structure of 3He. This nucleus is therefore very promising for the extraction of the neutron information. By increasing the momentum transfer, however, this conclusion is somehow hindered by the the fast growing proton contribution. Besides, even when the neutron contribution to the GPDs of 3He is largely dominating, the procedure of extracting the neutron GPDs from it could be, in principle, nontrivial. A technique is therefore proposed, independent on both the nuclear potential and the nucleon model used in ...

  8. Extracting generalized neutron parton distributions from 3He data

    Rinaldi, M.; Scopetta, S.

    2013-03-01

    An impulse-approximation (IA) analysis of the generalized parton distributions (GPDs) H and E of the 3He nucleus, quantities which are accessible in hard exclusive processes, such as coherent deeply virtual Compton scattering (DVCS), is described. The calculation is based on the Av18 interaction. The electromagnetic form factors are correctly recovered in the proper limits. The sum of the GPDs H and E of 3He, at low momentum transfer, is largely dominated by the neutron contribution, thanks to the unique spin structure of 3He. This nucleus is therefore very promising for the extraction of the neutron information. By increasing the momentum transfer, however, this conclusion is somehow hindered by the the fast growing proton contribution. Besides, even when the neutron contribution to the GPDs of 3He is largely dominating, the procedure of extracting the neutron GPDs from it could be, in principle, nontrivial. A technique is therefore proposed, independent of both the nuclear potential and the nucleon model used in the calculation, able to take into account the nuclear effects included in the IA analysis and to safely extract the neutron information at values of the momentum transfer large enough to allow the measurements. Thanks to this observation, coherent DVCS should be considered a key experiment to access the neutron GPDs and, in turn, the orbital angular momentum of the partons in the neutron.

  9. The {sup 3}He neutron-spin filter at ILL

    Tasset, F.; Heil, W.; Humblot, H.; Lelievre-Berna, E.; Roberts, T. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Neutron-Spin Filters (NSF) using gaseous polarised {sup 3}He have long been recognised as of enormous potential value in many polarised neutron-scattering applications and, accordingly, ILL started a development programme some years ago. This report gives an account of the present status of the project. (author). 13 refs.

  10. 3He-MRI of pulmonary ventilation: First clinical applications

    Purpose of the study is the visualisation of normal pulmonary ventilation in healthy volunteers and the evaluation of abnormalities in patients with different lung diseases using 3He magnetic resonance imaging (3He-MRI). Material und methods: Hyperpolarised 3He gas (V=300 ml, p=3x105 Pa, polarised to 35-45% by optical pumping, provided in special glass cells) was inhaled by eight healthy volunteers and ten patients with different lung diseases. A 3 D FLASH sequence (TR=11.8 ms; TE=5 ms; matrix 144x256, FOV 350 mm, section thickness 7-10 mm, coronal orientation) was performed in a single breath-hold (22-42 s). Clinical and radiological examinations were available for correlation. Results: The studies were successfully carried out in 8/8 volunteers and in 8/10 patients. The central airways were constantly visualised with intermediate to high signal instensity. The lung parenchyma of volunteers with normal ventilatory function showed rather homogeneous intermediate to high signal, whereas patients with chronic abstructive lung disease and/or pneumonia presented severe signal inhomogeneitises. Space-occupying lesions and pleural effusion caused large areas with little or no signal. The represented the lesion and adjacent ventilatory disturbances whose extent had not been presumed from chest X-ray or CT. The spatial resolution was higher than in ventilation scintigraphy. Conclusion: 3He MRI is a promising new modality for the assessment of pulmonary ventilation and its anormalies. (orig.)

  11. Minimal mass-size of a stable 3He cluster

    Guardiola Barcena, Rafael; Navarro Faus, Jesús

    2004-01-01

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

  12. Conceptual design of D-3He FRC reactor 'ARTEMIS'

    A comprehensive design study of the D-3He 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-3He 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-3He 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-3He FRC reactor are clarified. (author)

  13. Theoretical description of deeply virtual Compton scattering off $^3$He

    Rinaldi, Matteo

    2014-01-01

    Recently, coherent deeply virtual Compton scattering (DVCS) off $^3$He nuclei has been proposed to access the neutron generalized parton distributions (GPDs). In Impulse Approximation (IA) studies, it has been shown, in particular, that the sum of the two leading twist, quark helicity conserving GPDs of $^3$He, $H$ and $E$, at low momentum transfer, is dominated by the neutron contribution, so that $^3$He is very promising for the extraction of the neutron information. Nevertheless, such an extraction could be not trivial. A technique, able to take into account the nuclear effects included in the IA analysis in the extraction procedure, has been therefore developed. In this work, the IA calculation of the spin dependent GPD $\\tilde H$ of $^3$He is presented for the first time. This quantity is found to be largely dominated, at low momentum transfer, by the neutron contribution, which could be extracted using arguments similar to the ones previously proposed for the other GPDs. The known forward limit of the I...

  14. Electron elastic scattering and quark structure of 3He nucleus

    It is shown that for the interpretation of the behaviour of the 3He nucleus form factor at transfer momenta q > 6 fmsup(-1) of importance are nine-quark admixtures and their interference with nucleon and six-quark channels

  15. 3He(t,t)3He elastic scattering measurements from 9 to 17 MeV

    Angular distributions of the analyzing power and differential cross section for 3He(t,t)3He elastic scattering are reported for triton bombarding energies of 9.02, 11.00, 13.02, 15.02, 16.00, and 17.02 MeV, over a c.m. angular range from 25degree to 155degree. Excitation functions for the analyzing power are presented for the energy range 14.42--17.22 MeV. Problems in the phase-shift analysis of the data are discussed

  16. The electrodisintegration of 3He studied with the 3He(e,e'p)2H and 3He(e,e'd)1H reactions

    The author presents a survey of experimental and theoretical results for the ground-state properties of 3He. 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.)

  17. 3He(n,p) reaction simulation for formation analyses

    Computer modeling of neutron well logging instrument responses is becoming a necessity for petro-physical research and oil companies. It serves as a low-cost substitute for experimental test pits, as well as a means for obtaining data that are difficult to obtain experimentally. Neutrons in these tools are generally detected through 3He filled detectors. Detection of neutrons in a 3He counter occurs by means of the (n, p) reaction, yielding a proton and a triton. Computational simulation using the Monte Carlo code MCNP has been considered a powerful tool to simulate the response of neutron porosity tools. In the MCNP code the detection of neutrons in a 3He gas has been making by means of energy functions that convert neutron fluxes to reaction rates (n,p). It allows obtaining count values comparable with experimental data. However, it does not allow producing light ions from neutron capture reactions like triton and proton, and nor study the behavior of these particles as a function of the detector design. With the development of the version MCNPX 2.6, the simulation of light ions (protons, triton) from neutron capture reactions was made possible. The purpose of this work is to use the new capabilities included in the MCNPX 2.6 code to simulate the 3He(n,p) reaction for nuclear well logging applications. The results obtained confirm that it is useful to predict the count values, as it allows obtaining results comparable with the literature. Besides, the new capabilities of the MCNPX 2.6 allow producing the triton and proton reaction products and the expected pulse height spectrum from a 3He detector in which the wall effect is significant. (author)

  18. Functional {sup 3}He-MRI of the lungs; Funktionelle {sup 3}He-MRT der Lunge

    Gast, K.K.; Wolf, U. [Universitaetsmedizin der Johannes-Gutenberg-Universitaet Mainz, Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Mainz (Germany)

    2009-08-15

    Pulmonary diseases have a high health-related and economic significance. {sup 3}He-MRI is an alternative imaging method which can detect ventilatory disturbances with a high sensitivity. The application of different pulse sequences allows static and dynamic assessment of ventilation and bronchial gas flow, non-invasive measurement of intrapulmonary oxygen partial pressure and quantification of pulmonary parenchyma destruction and overinflation. Generally, the method is applicable for obstructive and restrictive ventilatory disturbances but initial approaches also exist for vascular pulmonary diseases. Specific clinical applications remain to be determined but {sup 3}He-MRI is an excellent instrument for the assessment of physiologic and pathophysiologic interrelations in the distribution of ventilation. (orig.) [German] Lungenerkrankungen haben einen hohen gesundheitlichen und volkswirtschaftlichen Stellenwert. Die {sup 3}He-MRT ist eine alternative bildgebende Methode, die sensitiv Ventilationsstoerungen nachweisen kann. Ueber unterschiedliche Pulssequenzen koennen Ventilation und Gasfluesse statisch und dynamisch dargestellt, der intrapulmonale Sauerstoffpartialdruck nichtinvasiv gemessen und die Destruktion und Ueberblaehung des Lungenparenchyms quantifiziert werden. Prinzipiell ist die Methode fuer die Untersuchung obstruktiver und restriktiver Ventilationsstoerungen anwendbar, Ansaetze existieren jedoch auch fuer vaskulaere Lungenerkrankungen. Spezifische klinische Anwendungen fuer die {sup 3}He-MRT muessen noch erarbeitet werden, sie ist jedoch ein hervorragendes Instrument zur Untersuchung physiologischer und pathophysiologischer Zusammenhaenge bei der Ventilationsverteilung. (orig.)

  19. Quasifree photoabsorption on neutron-proton pairs in 3He

    Three-body photodisintegration of 3He is calculated in the photon energy range 200-400 MeV assuming quasifree absorption on np pairs both in initial quasideuteron and singlet configurations. The model includes the normal nucleonic current, explicit meson exchange currents and the Δ(1232)-isobar excitation. The total cross section is increased by a factor of about 1.5 compared with free deuteron photodisintegration. Well below and above the Δ-region also some spin observables differ significantly from the ones of free deuteron disintegration due to the more compressed wave function of the correlated np pairs in 3He compared to the deuteron. The initial singlet state causes a significant change in the analysing power Ay. These differences could presumably be seen at the conjugate angles where two-body effects are maximized and where photoreactions could complement similar pion absorption experiments. ((orig.))

  20. Josephson flow oscillations in superfluid 3He-B

    Experiments for observing pressure-induced Josephson oscillations in superfluid 4He renewed the interest for analogous experiments in superfluid 3He. The weak coupling of two superfluids is obtained by a small channel with dimensions in the order of the coherence length. The order-parameter functions, the supercurrent Jψ through the orifice, and the Ginzburg-Landau free energy, Fψ is calculated for different cross sections. A new feature of the function Jψ in comparison to the current-phase relationships for superconducting microbridges is the occurrence of two nontrivial zeros of Jψ. It turns out that the frequency, ω, of the Josephson flow oscillations, which follow the sudden application of a force ΔF on a diaphragm, depends on ΔF in a way similar to that in which the frequency of the parallel ringing experiment in 3He-Α depends on the field step ΔΗ. (6 refs., 12 figs.)

  1. A polarized sup 3 He internal target for storage rings

    Poolman, H R; Bulten, H J; Doets, M; Ent, R; Ferro-Luzzi, M; Geurts, D G; Harvey, M; Mul, F A

    2000-01-01

    A polarized sup 3 He internal target was employed at the internal target facility of the Amsterdam electron Pulse Stretcher and Storage ring (AmPS) at the Dutch National Institute for Nuclear and High-Energy Physics (NIKHEF). The unique features of internal targets such as chemical and isotopic purity, high and rapidly reversible polarization, and the ability to manipulate the target spin orientation were successfully demonstrated. A nuclear polarization of 0.50 (0.42) at a sup 3 He gas flow of 1.0 (2.0)x10 sup 1 sup 7 at s sup - sup 1 could be obtained. Operation at a nominal flow of 1x10 sup 1 sup 7 at s sup - sup 1 resulted in a target thickness of 0.7x10 sup 1 sup 5 at cm sup - sup 2 at a target temperature of 17 K.

  2. A theory of low energy π-3He elastic scattering

    The main aim of this work is the construction of a first-order optical potential for the scattering of pions by 3He at low energy with as few approximations as possible. In particular the Fermi motion is treated extremely carefully by using microscopic 3He wave functions and by performing the complete Fermi-integral. Differential cross-sections and analyzing powers have been calculated. In a detailed comparison between the first-order optical with one which results from using the semi-factored approximation, it became clear that the latter has the following shortcomings: 1. the dependence of the subenergy on the pion-nucleus scattering angle, and 2. the independence of this energy on the relative motion of the spectator nucleons. (author). 101 refs.; 15 figs.; 3 tabs

  3. Photoassociation spectroscopy of ultracold metastable ^3He dimers

    Cocks, Daniel G; Whittingham, Ian B

    2011-01-01

    The bound states of the fermionic ^3He(2 ^3S_1)+ ^3He(2 ^3P_j)system, where j=0,1,2, are investigated using the recently available ab initio short-range ${}^{1,3,5}\\Sigma^{+}_{g,u}$ and ${}^{1,3,5}\\Pi_{g,u}$ potentials computed by Deguilhem et al. (J. Phys. B: At. Mol. Opt. Phys., 2009, 42, 015102). Single-channel and multichannel calculations have been undertaken in order to investigate the effects of Coriolis and non-adiabatic couplings. The possible experimental observability of the theoretical levels is assessed using criteria based upon the short-range character of each level and their coupling to metastable ground states. Purely long-range levels have been identified and 30 short-range levels near five asymptotes are suggested for experimental investigation.

  4. Studies of 3He Induced Nuclear Reactions on Cadmium

    Excitation functions of 3He induced nuclear reactions on natural cadmium were measured using the standard stacked foil technique and high resolution gamma ray spectroscopy. The experimental cross sections for the nuclear reactions natCd(3He,xnp )117m,g,116m115m,114m,113m,111,110m,g,109,108,107 In were measured from their threshold energy up to 27 MeV. The integral yields for some medically important products were determined. Theoretical calculations using the nuclear codes ALICE- IPPE, TAL YS, and EMPIRE-3 were used to describe the formation of these products. Theoretical and experimental results were compared with each other. K

  5. Nuclear (K) Bound States in 4He and 3He

    LI Yi-He; WU Shi-Shu

    2009-01-01

    @@ We construct a phenomenological K N interaction which reproduces the two resonances: the energy of the first resonance is 1420MeV and the other is 1392MeV. The A(1405) is found by a superposition of the two reso-nances with appropriate weights. Within the framework of the Brueckner-Hartree-Fock theory, we have studied K- - 3He(T=0) and K- - 4He(T=1/2). The binding energy BK-is 93MeV(72MeV) and the width F is 13 MeV(25 MeV) for K- - 3He(T=0) (K- - 4He(T=1/2)).

  6. Project of polarized 3He source at RARF

    At RIKEN Accelerator Research Facility (RARF), a K540 four-sector ring cyclotron (RRC) was completed in November 1986, and has delivered beams to the experiments since May 1987. At present, a heavy-ion linac (RILAC) with a PIG source is used as an injector for RRC. The construction of another injector, a K70AVF cyclotron, has been started and will be completed at the end of 1988 FY. The AVF cyclotron is equipped with a polarized 3He source as well as an ECR source and a duoplasmatron source. The nuclear polarization of 3He will be obtained with the optical pumping of atoms in the metastable state (23 S1) followed by the metastability exchange collision. Polarized atoms will be ionized with an ECR source. The source is expected to be constructed in three years. (author)

  7. Magnetism of liquid 3He up to 200 T

    We report measurements of nuclear magnetism of degenerate liquid 3He below 0.1 K. Nuclear polarization up to 60% was transiently obtained by rapid melting of a 80% polarized 3He solid. From simultaneous measurements of the magnetization and of the heat released during the relaxation towards magnetic equilibrium, we deduce the magnetization dependence of the free energy of the liquid, and hence the magnetization curve up to 200 T. At 26 bar and 80 mK, we find that the susceptibility decreases with increasing magnetization. This rules out any significant metamagnetism of the liquid, in contradiction with former expectations. In order to confirm this behaviour by a static experiment, we have developed a torque magnetometer to carry out precision measurements of the equilibrium magnetization up to 30 T (corresponding to a 12% polarization) and at 50 mK. Preliminary results of this experiment are reported. (orig.)

  8. Transverse sound in liquid-3He-aerogel system

    Transverse sound in normal liquid 3He in aerogel is studied on the basis of the Landau transport equation taking into account the simultaneous oscillation of the aerogel. We show that the nature of transverse sound is strongly modified if aerogel is immersed in the liquid. Scattering of 3He quasiparticles by the aerogel molecules causes friction between the liquid and the aerogel, giving rise to coupled motion of the two systems. There exists a low-attenuation transverse sound mode in this coupled system. The high-temperature behavior of its attenuation α is given by α∝const+T-2, which is in contrast to α∝T in pure liquid H3e in the hydrodynamic regime

  9. Acoustic properties of superfluid 3He in 97% aerogel

    Superfluid 3He in silica aerogel provides a unique system for studying the effect of quenched disorder in the unconventional superfluid. We have performed longitudinal ultrasound (5.7 MHz) attenuation and sound velocity measurements of the superfluid 3He in 97% porosity aerogel. The attenuation and sound velocity were determined by direct propagation of sound pulses through the medium in a wide range of temperatures, down to 400 μK. The superfluid transition, marked by the increase in sound velocity, is substantially suppressed from that in 98% aerogel used in most of studies. The superfluid fraction determined from the sound velocity is less than 0.02 even at the lowest temperature.

  10. 3He melting curve thermometry in a nuclear polarization experiment

    Temperature measurement and control are important in brute force polarization experiments. We discuss the installation and use of 3He melting curve thermometers in a cryostat used to polarize a TiH2 target. Comparison is made between the melting curve thermometers and the 60CoCo nuclear orientation thermometer, which is often used in such experiments. The melting curve thermometers provide increased temperature resolution and sensitivity, and were used in a feedback heating system to control temperature to ±5.5 μK at 16.5 mK. The 3He melting curve and the 60CoCo temperature scales are found to agree within 2% at 15 mK. The present status of the melting curve scale and the effect of a magnetic field on melting curve thermometry are also discussed. (orig.)

  11. Fluctuations above the superfluid transition in liquid 3He

    It is shown that fluctuations above the superfluid transition in liquid 3He depend strongly upon the relative angular momentum l of a Cooper pair but are insensitive to the fourth order term in the Ginsburg-Landau free energy. The effects are shown to be observable in the static magnetization, viscosity and spin diffusion and give a means of determining the value of l. (U.S.)

  12. Phase slippage in superfluid 3He-B

    We review some applications of the hydrodynamic Josephson effects. The relationship between the quantum mechanical phase difference along a micro-orifice and the flow through it is discussed in terms of a simple model which accounts for the observations performed in 3He-B above 0.7 Tc. Possible uses of the superfluid hydromechanical resonator as a sensitive and stable absolute gyrometer are described

  13. A study of 3He films using SQUID NMR

    Confinement of superfluid 3He to a geometry of order the coherence length is predicted to produce interesting size effects and modify the superfluid phase diagram. This thesis describes the development of an experiment to measure these effects using NMR as a probe of the spin dynamics. A pulsed NMR spectrometer was developed with a low Tc SQUID as the first stage amplifier. The sample was located in a receiver coil that formed part of a tuned circuit with the SQUID input coil. The first spectrometer was operated in an open-loop configuration but was later converted to use feedback to stabilize the SQUID gain. This later version used a DC SQUID with APF operating in flux-locked loop using the Direct Offset Integration Technique. The noise was limited by the Johnson noise in the tuned circuit in tests down to 1.5 K and the estimated noise temperature was ∼100 mK. NMR signals were observed at ∼1 MHz from low-density 3He samples adsorbed on a Mylar substrate which were in reasonable agreement with the estimated signal sizes. A cell was constructed with a highly polished silver substrate to study a 100 nm thick 3He film adsorbed on an area of ∼1 cm2. This was mounted on a newly installed demagnetization cryostat. A dipper probe was constructed for the SQUID spectrometer which demonstrated an overall coupled energy sensitivity of 327 h before being mounted on the cryostat. NMR signals were observed from samples equivalent to films of thickness 100, 400, and 800 nm on the substrate surface at temperatures ranging from 60 mK down to 415 μK. No superfluid transition was detected. With each sample a time dependence of the signal was observed which may be attributable to a thermomechanical effect in normal liquid 3He. Based on the measured signals, it is predicted that ∼1016 spins should be detectable in a single-shot. (author)

  14. Hard Two-body Photodisintegration of 3He

    Pomerantz, I; Gilman, R; Higinbotham, D W; Piasetzky, E; Strauch, S; Adhikari, K P; Aghasyan, M; Allada, K; Amaryan, M J; Pereira, S Anefalos; 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; Alaoui, A El; Fassi, L El; 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; Camacho, C Munoz; 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; Sabatie, 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

    2013-01-01

    We have measured cross sections for the gamma+3He->p+d reaction at photon energies of 0.4 - 1.4 GeV and a center-of-mass angle of 90 deg. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

  15. Orbital angular momentum in /sup 3/He-A-italic

    Balatskii-breve, A.V.; Mineev, V.P.

    1985-12-01

    The intrinsic angular momentum in the A-italic phase of superfluid /sup 3/He is found in terms of the response to the angular velocity of rotation. It is shown that in the weak-coupling approximation at an arbitrary temperature and with allowance for the Fermi-liquid renormalization the intrinsic angular momentum is small in accordance with the smallness of the asymmetry in the distribution of particles and holes.

  16. Investigating Neutron Polarizabilities through Compton Scattering on $^3He$

    Choudhury, D.; Nogga, A.; Phillips, D.R.

    2007-01-01

    We examine manifestations of neutron electromagnetic polarizabilities in coherent Compton scattering from the Helium-3 nucleus. We calculate $\\gamma ^3He$ elastic scattering observables using chiral perturbation theory to next-to-leading order (${\\mathcal O}(e^2 Q)$). We find that the unpolarized differential cross section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four ...

  17. Hard Photodisintegration of 3He into pd pair

    Maheswari, Dhiraj

    2016-01-01

    The recent measurements of high energy photodisintegration of the $^3He$ nucleus to the $pd$ pair at $90^0$ center of mass demonstrated an energy scaling consistent with the quark counting rule with unprecedentedly large exponent of $s^{-17}$. To understand the underlying mechanism of this process we extended the theoretical formalism of hard rescattering mechanism to calculate the $\\gamma ^3He\\rightarrow pd$ reaction. In HRM the incoming high energy photon strikes a quark from one of the nucleons in the target which subsequently undergoes hard rescattering with the quarks from the other nucleons generating hard two-body system in the final state of the reaction. Within the HRM we derived the parameter free expression for the differential cross section of the reaction, which is expressed through the $^3He\\rightarrow pd$ transition spectral function, cross section of hard $pd\\rightarrow pd$ scattering and the effective charge of the quarks being interchanged during the hard rescattering process. The numerical ...

  18. High Efficiency Spin Flipper for the n3He Experiment

    Hayes, Christopher; n3He Collaboration

    2015-10-01

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

  19. Saddle point condition for D - 3He tokamak fusion reactor

    In this paper the concept of a generalized ignition contour map, showing bar PhtT2E, NTE, and T, is used to study the ignition criterion for a D-3He fusion reactor with plasma temperature and density profiles. Direct heating scenarios to the D - 3He ignition regime without the help of deuterium-tritium burning are considered. The machine size and enhancement factor for the confinement time required to reach D - 3He ignition can be simple determined by comparing the height of the operation path with Goldston L-mode scaling and the height of the generalized saddle point. A confinement enhancement factor of 2 to 3 is required in the case of a large plasma current (30 to 80 MA) in a small-aspect-ratio tokamak. On the other hand, for a small plasma current (approx-lt 10 MA), large-aspect-ratio tokamak, an enhancement factor of 5 to 6 is necessary to reach ignition. Fuel dilution effects by fusion products and impurities, the confinement degradation effect due to 14-MeV protons, and the operation paths are also considered. To lower the height of the saddle point, and hence the auxiliary heating power, we optimize the fuel composition and examine operation in the hot ion mode

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

    Development of a He-3 power controlled boiling water capsule, 3He-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 3He-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 3He-BOCA for power ramping of a short fuel pin from 250 W/cm to 500 W/cm under BWR conditions. (author)

  1. Superfluid phase stability of 3He in axially anisotropic aerogel

    Measurements of superfluid 3He in 98% aerogel demonstrate the existence of a metastable A-like phase and a stable B-like phase. It has been suggested that the relative stability of these two phases is controlled by anisotropic quasiparticle scattering in the aerogel. Anisotropic scattering produced by axial compression of the aerogel has been predicted to stabilize the axial state of superfluid 3He. To explore this possibility, we used transverse acoustic impedance to map out the phase diagram of superfluid 3He in a ∼ 98% porous silica aerogel subjected to 17% axial compression. We have previously shown that axial anisotropy in aerogel leads to optical birefringence and that optical cross-polarization studies can be used to characterize such anisotropy. Consequently, we have performed optical cross-polarization experiments to verify the presence and uniformity of the axial anisotropy in our aerogel sample. We find that uniform axial anisotropy introduced by 17% compression does not stabilize the A-like phase. We also find an increase in the supercooling of the A-like phase at lower pressure, indicating a modification to B-like phase nucleation in globally anisotropic aerogels.

  2. Precision study of the eta-3He system using the d+p->3He+eta reaction

    Mersmann, T; Chiladze, D; Dymov, S; Hartmann, M; Hejny, V; Kacharava, A K; Keshelashvili, I; Khoukaz, A; Kulessa, P; Maeda, Y; Mielke, M; Mikirtychiants, S; Ohm, H; Papenbrock, M; Prasuhn, D; Rathmann, F; Rausmann, T; Schleichert, R; Serdyuk, V; Stein, H J; Ströher, H; Täschner, A; Valdau, Y; Wilkin, C; Wro'nska, A; Valdau, Yu.

    2007-01-01

    The differential and total cross sections for the d+p->3He+eta reaction have been measured in a high precision high statistics COSY-ANKE experiment near threshold using a continuous beam energy ramp up to an excess energy Q of 11.3 MeV with essentially 100% acceptance. The kinematics allowed the mean value of Q to be determined to about 9 keV. Evidence is found for the effects of higher partial waves for Q>4 MeV. The very rapid rise of the total cross section to its maximum value within 0.5 MeV of threshold implies a very large eta-3He scattering length and hence the presence of a quasi-bound state extremely close to threshold.

  3. Superfluid phase of 3He-B near the boundary

    Following our analysis of some older and most recent transverse sound experiments in superfluid 3He-B we have been able to solve one of the long-existing problem of superfluid quantum liquids in confined geometry, namely, answer a question what is the boundary state of 3He-B. We have devoted specific attention to the differences between transverse sound experiments data from that obtained in longitudinal sound experiments. In our analysis, we have considered several potentially possible explanations of the above experimental data: existence of a new superfluid phase in the vicinity of the boundary; excitation of different branches of squashing mode by longitudinal and transverse sounds and, finally, deformation of the B-phase near the boundary. The last possibility seems to be the most likely explanation implying that the boundary state of 3He-B is, in fact, the deformed B- phase, as was first suggested by Brusov and Popov about two decades ago for a case of presence of external perturbations such as a magnetic and an electric fields. Our result implies that influence of a wall or, in other words, a confined geometry does not lead to the existence of a new phase near the boundary, as had been suggested many years ago, but, instead, similarly to the case of other external perturbations (such as magnetic, electric fields etc.), the wall deforms the order parameter of the B-phase and this deformation leads to several very important consequences. For example, frequencies of the collective modes in the vicinity of the boundary change by up to about 20 percent.

  4. Hard breakup of two nucleons from the 3He nucleus

    We investigate a large angle photodisintegration of two nucleons from the 3He nucleus within the framework of the hard rescattering model (HRM). In the HRM a quark of one nucleon knocked out by an incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with large relative momentum. Assuming the dominance of the quark-interchange mechanism in a hard nucleon-nucleon scattering, the HRM allows the expression of the amplitude of a two-nucleon breakup reaction through the convolution of photon-quark scattering, NN hard scattering amplitude, and nuclear spectral function, which can be calculated using a nonrelativistic 3He wave function. The photon-quark scattering amplitude can be explicitly calculated in the high energy regime, whereas for NN scattering one uses the fit of the available experimental data. The HRM predicts several specific features for the hard breakup reaction. First, the cross section will approximately scale as s-11. Second, the s11 weighted cross section will have the shape of energy dependence similar to that of s10 weighted NN elastic scattering cross section. Also one predicts an enhancement of the pp breakup relative to the pn breakup cross section as compared to the results from low energy kinematics. Another result is the prediction of different spectator momentum dependencies of pp and pn breakup cross sections. This is due to the fact that the same-helicity pp-component is strongly suppressed in the ground state wave function of 3He. Because of this suppression the HRM predicts significantly different asymmetries for the cross section of polarization transfer NN breakup reactions for circularly polarized photons. For the pp breakup this asymmetry is predicted to be zero while for the pn it is close to (2/3).

  5. Vortex clusters in superfluid 3He-B

    A unique property of 3He-B is vortex-free rotation, due to a high nucleation threshold of the singular vortices. In contrast to other superfluids, rotational states consisting of a vortex cluster surrounded by vortex-free counterflow form spontaneously and can also be prepared with a fixed number of vortices. The clusters can be analyzed by means of NMR measurements with high precision. These techniques have been exploited to study rotational states in the presence of different phase boundaries. (orig.)

  6. Meson Photoproduction off the Deuteron and off 3He

    Photoproduction of mesons off the deuteron and He nuclei has been studied at the tagged photon facilities of the Bonn ELSA accelerator and the Mainz MAMI accelerator with the Crystal/ setup (Mainz). Meson photoproduction off the neutron has been investigated for different final states (πo, πo πo, πo π-, η, η', ηπo). A surprising finding was a narrow structure in the γn→nη excitation function, which is not seen in the proton case. Photoproduction off 3He has provided further evidence for the formation of an h-mesic state.

  7. High-pressure /sup 3/He gas scintillation neutron spectrometer

    Derzon, M.S.; Slaughter, D.R.; Prussin, S.G.

    1985-10-01

    A high-pressure, /sup 3/He-Xe gas scintillation spectrometer has been developed for neutron spectroscopy on D-D fusion plasmas. The spectrometer exhibits an energy resolution of (121 +- 20 keV) keV (FWHM) at 2.5 MeV and an efficiency of (1.9 +- 0.4) x 10/sup -3/ (n/cm/sup 2/)/sup -1/. The contribution to the resolution (FWHM) from counting statistics is only (22 +- 3 keV) and the remainder is due predominantly to the variation of light collection efficiency with location of neutron events within the active volume of the detector.

  8. /sup 3/He and 4f instable compounds

    Flouquet, J.; Jaccard, J. (Centre de Recherches sur les Tres Basses Temperatures, C.N.R.S., 38 - Grenoble (France)); Ribault, M. (Laboratoire de Physique des Solides, Universite de Paris-Sud, 91 - Orsay (France))

    1984-01-01

    The high localization of the 4f electron and the possibility of a weak delocalization through the coupling with the itinerant electrons lead to Fermi liquid properties. With the example of CeAl/sub 3/, the main role of the coherence between the Ce is emphasized at low temperature. Thermal dilatation data show the transition from a regime of almost independent Kondo centers to a regime of coherent Kondo centers. The occurence of the superconductivity in the heavy fermion CeCu/sub 2/Si/sub 2/ is discussed and compared to the superfluidity of liquid /sup 3/He.

  9. Hyperpolarised {sup 3}He MRI and {sup 81m}Kr SPECT in chronic obstructive pulmonary disease

    Stavngaard, Trine [Copenhagen University Hospital, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet (Denmark); Copenhagen University Hospital, Danish Research Centre for Magnetic Resonance, Hvidovre (Denmark); Soegaard, Lise Vejby; Hanson, Lars G. [Copenhagen University Hospital, Danish Research Centre for Magnetic Resonance, Hvidovre (Denmark); Mortensen, Jann; Berthelsen, Anne Kiil [Copenhagen University Hospital, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet (Denmark); Schmiedeskamp, Joerg [Johannes Gutenberg Universitaet, Institut fuer Physik, Mainz (Germany); Dirksen, Asger [Gentofte University Hospital, Department of Respiratory Medicine, Hellerup (Denmark)

    2005-04-01

    During recent years, magnetic resonance imaging (MRI) using hyperpolarised (HP) {sup 3}He gas has emerged as a promising new method for the imaging of lung ventilation. However, systematic comparisons with nuclear medicine techniques have not yet been performed. The aim of this study was to compare ventilation imaging methods in 26 patients with chronic obstructive pulmonary disease (COPD) and nine lung healthy volunteers. HP {sup 3}He MRI, {sup 81m}Kr single-photon emission computed tomography (SPECT), high-resolution computed tomography (HRCT) and pulmonary function tests were performed. The three scans were scored visually as percentage of non-ventilated/diseased lung, and a computer-based objective measure of the ventilated volume in HP {sup 3}He MRI and {sup 81m}Kr SPECT and an emphysema index in HRCT were calculated. We found a good correlation between HP {sup 3}He MRI and {sup 81m}Kr SPECT for both visual defect score (r=0.80, p<0.0001) and objective estimate of ventilation (r=0.45, p=0.0157). In addition, both scans were well correlated with reference methods for the diagnosis of emphysema (pulmonary function test and HRCT). The defect scores were largest on {sup 81m}Kr SPECT (the score on HP {sup 3}He MRI was one-third less than that on {sup 81m}Kr SPECT), but the difference was reduced after normalisation for different breathing depths (HP {sup 3}He MRI at total lung capacity; {sup 81m}Kr SPECT at tidal breathing at functional residual capacity). HP {sup 3}He MRI provides detailed ventilation distribution images and defect scores are comparable on HP {sup 3}He MRI and {sup 81m}Kr SPECT. Additionally, new insights into the regional pulmonary microstructure via the apparent diffusion coefficient measurements are provided by HP {sup 3}He MRI. HP {sup 3}He MRI is a promising new diagnostic tool for the assessment of ventilation distribution. (orig.)

  10. The 3H-3He Charge Radii Difference

    Myers, Luke S. [Bluffton University, Bluffton, OH; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Arrington, John R. [Argonne National Lab. (ANL), Argonne, IL (United States); Higinbotham, Douglas W. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-03-01

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

  11. Study of response of 3He detectors to monoenergetic neutrons

    In the search of a hybrid system (the coupling of the particle accelerator to an under-critical reactor) for radioactive waste transmutation the TARC (Transmutation by Adiabatic Resonance Crossing) program has been developed. Due to experimental limitations, the time-energy relation at higher neutron energies, particularly, around 2 MeV, which is an important domain for TARC, cannot be applied. Consequently the responses of the 3He ionization neutron detector developed for TARC experiment have been studied using a fast monoenergetic neutron source. The neutrons were produced by the interaction of the proton delivered by Van de Graaff accelerator of CENBG. The originality of the detector consists in its structure of three series of electric conductors which are mounted around the anode: a grid ensuring the detector proportionality, a cylindrical suit of alternating positive voltage and grounded wires aiming at eliminating the radial end effects, serving as veto and two cylinders serving as end plugs to eliminate the perpendicular end effects. Examples of anode spectra conditioned (in anticoincidence) by the mentioned vetoes are given. One can see the contribution of the elastic scattering from H and 3He. By collimating the neutron beam through a borated polyethylene system it was possible to obtain a mapping of the detector allowing the study of its response as a function of the irradiated zones (anode and grid)

  12. Neutron scattering from liquid {sup 3}He at intermediate energies

    Guckelsberger, K. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Azuah, R.T. [Department of Physics, Keele University, Keele Staffordshire, ST5 5BG (United Kingdom)]|[Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0Qx (United Kingdom); Stirling, W.G. [Keele University (United Kingdom); Bennington, S.M.; Yates, M. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0Qx (United Kingdom)

    1997-06-01

    Understanding the dynamics of strongly interacting quantum liquids is at the heart of much of contemporary physics and the archetypal Fermi liquid is {sup 3}He at low temperatures. However, due to the enormous absorption of neutrons by {sup 3}He, experiments are exceedingly difficult. At very high incident neutron energies (>1 eV), the struck atoms behave as if they were free. In a sense, one can ``switch on the interaction`` by using neutrons with ever lower energies until they are-near 1 meV-comparable to that of the interaction. In the present work we use 80-400 meV neutrons to resolve a long standing puzzle: previous measurements suggested strong fluctuations in the width of the recoil peak that could not be understood in terms of a simple theory. Using improved instrumentation (MARI at the spallation source) and novel sample cell design we could improve statistics by more than one order of magnitude. The new data covering an extended energy range are presented and seem to confirm the theory. (orig.).

  13. Longitudinal nuclear magnetic resonance of 3He-B superfluid

    Experiments which contribute to a better understanding of the 3He superfluid in the B phase are reported: a/ The first direct determinations of the gap parameter at zero temperature are given and the longitudinal N.M.R. frequency signal is measured for various pressures. b/ These experiments show a new saturation phenomenon in the ringing signal decay time Tsub(R)(T) at low temperatures. c/ Under conditions of slight non-linearity the excitation of 3He-B longitudinal N.M.R. gives rise to a special system wherein the ringing signal decay is all the faster as the excitation is stronger. A so-called ''memory'' time is measured distinctly longer than the ringing time measured under quasi-linear excitation conditions. It was found that the ringing signal decay, at first exponential for weak excitations γH1 approximately 7 10-3 Ωsub(L), becomes quasi-linear when the excitation is about γH1 approximately 10-2Ωsub(L). This abnormal behaviour cannot be explained by thermal effects related to N.M.R. excitation nor by inhomogeneity effects of the excitation magnetic field. Our interpretation is that excitations γH1 approximately 10-2 Ωsub(L) cause structural defects in the orientation of the vector n which are found to disappear according to an exponential law in times of around 10 ms

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

    We report on the first experimental results for microwave spectroscopy of the hyperfine structure of p-bar3He+. Due to the helium nuclear spin, p-bar3He+ has a more complex hyperfine structure than p-bar4He+, which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton.

  15. Hard photodisintegration of a proton pair in {sup 3}He

    Stanley Brodsky; Leonid Frankfurt; Ronald Gilman; J. R. Hiller; G. A. Miller; Eliezer Piasetzky; Misak Sargsian; Mark Strikman

    2003-05-01

    Hard photodisintegration of the deuteron has been extensively studied in order to understand the dynamics of the transition from hadronic to quark-gluon descriptions of the strong interaction. In this work, we discuss the extension of this program to hard photodisintegration of a pp pair in the {sup 3}He nucleus. Experimental confirmation of new features predicted here for the suggested reaction would advance our understanding of hard nuclear reactions. A main prediction, in contrast with low-energy observations, is that the pp breakup cross section is not much smaller than the one for pn break up. In some models, the energy-dependent oscillations observed for pp scattering are predicted to appear in the {gamma} {sup 3}He {yields} pp + n reaction. Such an observation would open up a completely new field in studies of color coherence phenomena in hard nuclear reactions. We also demonstrate that, in addition to the energy dependence, the measurement of the light-cone momentum distribution of the recoil neutron provides an independent test of the underlying dynamics of hard disintegration.

  16. The 3H–3He Charge Radii Difference

    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.

  17. Study of 40Ca(3He,t)40Sc and 9Be(3He,t)9B reactions

    The objective of this research thesis is to perform additional experiments for a better definition of the interaction occurring during the (3He,t) charge exchange reaction, notably in the case of transitions between different layers, and in the case of a target nucleus with a non null spin. In this respect, this thesis addresses the study of 40Ca and 9Be nuclei. After a description of experimental devices and of the obtained performance, the author reports the development of microscopic calculation model within the framework of the DWBA (Distorted Wave Born Approximation). Experimental results are then presented, analysed and discussed

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

    Çetin, Füsun

    2004-07-01

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

  19. Hyperpolarised sup 3 He gas production for magnetic resonance imaging of the human air ways

    Fichele, S

    2002-01-01

    This thesis describes the experimental techniques, and methods employed in hyperpolarised sup 3 He gas production and magnetic resonance imaging of the human air-ways, using spin-echo sequences and MR tagging techniques. An in-house polariser utilising the metastability optical pumping technique was constructed. The main results of this work are concerned with engineering difficulties involved in compressing HP sup 3 He and a large proportion of this PhD thesis details the design, construction, and performance of an in-house built peristaltic compressor. In preliminary imaging experiments using RARE, high signal to noise projection images of the lungs were acquired using less than 0.5 cm sup 3 (STP) of purely polarised HP gas. Later, increased HP gas quantities (typically 10 cm sup 3) were obtained by employing the peristaltic compressor. Consequently we could acquire 10 mm thick slices spanning the entire lung following a single sup 3 He gas bolus administration. Finally, the first results using MR tagging t...

  20. Nuclear spin dynamics in solid 3He at ultralow temperatures

    In this thesis the experimental study of the spin dynamics of solid 3He is described. By means of magnetization measurements above 3 mK a Curie-Weiss behaviour was found with θW∼2.1 mK and by this an order parameter of J=θWkB/∼-0.5 KkB was observed, while in the range of 1 to 3 mK a pure Curie behaviour was found. By means of NMR measurements the values of τ1(6 mK)=240 ms±12 ms and τ1(1 mK)∼ 40 ms were determined, while spin-echo measurements yielded the spin-spin relaxation time τ2(6 mK)=4540 μs±140 μs. Furthermore neutron scattering studies were performed. (HSI)

  1. Vortex structure in rotational state superfluid 3He

    The structure of vortices in rotational superfluid 3He is considered. It is marked that in the A-phase quantum vortices are possible, in which the A-phase superfluid state is never disturbed. As a consequence of a discrete combined invariance (calibration transformation plus rotation of a spin subsystem) one more exotic type of vortices is possible in the A-phase. This is a hybrid of disclination in a magnetic anisotropy vector field d (with a half-integer Frank index) and vortex that possesses a half-integer number of circulation quanta. Such vortices can be observed at rotation of the A-phase confined between parallel plates. The vortex properties in the B-phase are determined by a continuous combined symmetry. The calculations show the vortex in the β-phase at low pressures to be in the ν-state. The vortices considered are observed in the NMR experiments

  2. APT 3He target/blanket. Topical report

    The 3He target/blanket (T/B) preconceptual design for the 3/8-Goal facility is based on a 1000-MeV, 200-mA accelerator to produce a high-intensity proton beam that is expanded and then strikes one of two T/B modules. Each module consists of a centralized neutron source made of tungsten and lead, a proton beam backstop region made of zirconium and lead, and a moderator made of D2O. Helium-3 gas is circulated through the neutron source region and the blanket to create tritium through neutron capture. The gas is continually processed to extract the tritium with an online separation process

  3. Preparations for HFS spectroscopy of antiprotonic 3He

    Full text: Antiprotonic helium (pHe) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta and spins of its constituents cause splitting within the principle states. The measured transition frequencies between hyperfine levels can be compared with three-body QED calculations as a test of the theory. Previous measurements have been performed on p4He. The next two years will be dedicated to measuring a similar transition within p3He. Due to the additional coupling to the helion spin, it consists of an octuplet of states instead of a quadruplet. A new microwave cavity has been designed and is being constructed for the transition frequency of 11.14 GHz. This cavity has been simulated using the high frequency structure simulator HFSS to obtain the correct cavity dimensions. A new cryostat to cool the target is under construction. Numerical simulations are also in progress. (author)

  4. Muon capture on the deuteron and 3He

    Elmeshneb A. E.

    2014-01-01

    Full Text Available We plan to investigate the role of meson exchange currents in the description of the µ− + d → νµ + n + n and µ− + 3He → νµ + 3H reactions. They both are treated as the decay of the corresponding muonic atoms, with the muon initially on the lowest K shell. The muon binding energy in these atoms can be safely neglected and in the initial state we deal essentially with the deuteron (or 3He and muon at rest. These two reactions are interesting for several reasons. First of all, they offer a testing ground for the nuclear wave functions, which for any nucleon-nucleon (NN and three-nucleon (3N forces can be constructed for such light systems with great accuracy. In these reactions few-nucleon weak current operators are an important dynamical ingredient. In the current operators apart from the relatively well known single nucleon contributions, two-nucleon parts (generated by various meson exchanges play an important role. Their details are not well known and several models should be considered. We present our formalism for dealing with these reactions and a simple method for partial wave decomposition of the two-nucleon operators. The crucial nuclear matrix elements of the corresponding weak current operators will be calculated in the momentum space and using partial wave decomposition. The effect of meson exchanges will be investigated in the energy spectrum of the emitted neutrinos (in the deuteron case and in the total decay rates for the two reactions. We will employ various models of NN and 3N forces, such as the Bonn B or chiral NNLO potentials. Our results with the single nucleon currents look already very promising and we hope for the improvement in the description of the experimental data, when dominant two-nucleon current operators are included in our framework.

  5. Nuclear spin dynamics in solid {sup 3}He at ultralow temperatures; Kernspindynamik in festem {sup 3}He bei ultratiefen Temperaturen

    Kath, Matthias

    2009-11-06

    In this thesis the experimental study of the spin dynamics of solid {sup 3}He is described. By means of magnetization measurements above 3 mK a Curie-Weiss behaviour was found with {theta}{sub W}{approx}2.1 mK and by this an order parameter of J={theta}{sub W}k{sub B}/{approx}-0.5 Kk{sub B} was observed, while in the range of 1 to 3 mK a pure Curie behaviour was found. By means of NMR measurements the values of {tau}{sub 1}(6 mK)=240 ms{+-}12 ms and {tau}{sub 1}(1 mK){approx} 40 ms were determined, while spin-echo measurements yielded the spin-spin relaxation time {tau}{sub 2}(6 mK)=4540 {mu}s{+-}140 {mu}s. Furthermore neutron scattering studies were performed. (HSI)

  6. The interfacial thermal resistance between bulk superfluid 3He and liquid 3He in aerogel at ultralow temperatures

    We present the first measurements of the thermal boundary resistance of the interface between the two different liquid phases: bulk superfluid and liquid confined in aerogel. We set up a heat flow along a liquid-filled tube containing a plug of 98% aerogel, and measure the temperature at the two ends. At the lowest temperatures, the resistance is dominated by the boundary resistance at the aerogel surfaces and is unaffected by the superfluid transition of the 3He in the aerogel. Whereas in conventional Kapitza resistance the boundary conductance is limited by acoustic mismatch, here the conductance is limited by an energy mismatch, since quasiparticles with energies above the bulk B-phase gap may freely cross the interface, while those with lower energies are confined to the aerogel

  7. Executive summary: advanced-fuel fusion systems, the D-3He satellite approach

    An evaluation was made of the potential advantages and feasibility of fusion power plants designed to employ near-term non-D--T fuels such as deuterium and D-3He. The following topics are discussed here: (1) cost studies and net-energy analysis, (2) D-3He Bumpy Torus satellite, (3) exploratory studies of a D-3He field-reversed mirror satellite, (4) preliminary advanced fuel pellet studies, and (5) 3He neutral beam injector

  8. NMR studies on vortices in rotating 3He-A

    NMR measurements are reported on rotating 3He-A in a long cylindrical geometry of 5 mm diameter at a liquid pressure of 29.3 bar and in axial magnetic fields of 14.2, 28.4, and 56.9 mT. At 28.4 mT, NMR studies are also reported in fields inclined by 250 and 900 from the axis of rotation. The frequency shift, the width, and the intensity of the spin wavemodes localized on the soft vortex cores, as well as the additional broadening of the main NMR line during rotation, were measured as a function of temperature, angular velocity Ω, magnetic field intensity, and its inclination angle. Also observed were a critical angular velocity of vortex formation, hysteretic behavior in the number of vortices when comparing accelerating rotation to decelerating, and metastable vortex densities, presumably a vortex tangle after rapid oscillatory acceleration. The results can be understood in terms of the continuous 4π vortices first proposed by Seppaelae and Volovik

  9. Vortex sheet in superfluid 3He-A

    A new state of rotating superfluid 3He-A has been found recently. Usually superfluids respond to rotation by creating an array of vortex lines, which are parallel to the rotation axis, and the circulation around them is quantized. In the new state the vorticity is located on a 2 dimensional sheet instead of 1 D lines. The sheet is parallel to the rotation axis z but in the x - y plane it folds to equidistant layers. The distance between the layers is larger but on the same order of magnitude as the distance between vortex lines. In contrast to other superfluids, the sheet is stable in the A phase because, of its internal structure. The sheet has as a backbone a topologically stable domain wall called soliton, to which non-singular vorticity is bound. Thus it can exist in spite of its presumably higher energy. The vortex sheet is distinguished by its NMR response, in particular because of its higher absorption at a characteristic frequency. Experiment and theory on the vortex sheet are in good agreement

  10. Negative pion absorption at rest in 3He

    The pnn and dn final states after the absorption of stopped pions in 3He have been measured in a kinematically complete experiment covering the whole phase space. Proton-neutron, deuteron-neutron, and neutron-neutron coincidences have been detected with a charged-particle hodoscope and large-area time-of-flight counters. For the first time, triple coincidences between the pionic K x rays and two particles have been measured thus selecting absorption from the atomic 1s state. It has been found that the absorption is dominated by the two-nucleon mechanism (2NA) on isoscalar nucleon pairs as indicted by the measured ratio of 6.3±1.1 for back-to-back correlated nn and pn pairs. A substantial amount of the three-body final state pnn is affected by the final-state interaction (FSI) or leads to the two-particle final state dn. Ratios of 3.1±0.4 for 2NA to FSI and of 4.2±0.6 for the pnn to the dn final state are measured. No evidence has been found for three-nucleon absorption with an upper limit of %/πstop-

  11. Andreev reflection in rotating superfluid 3He-B

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

  12. Measurement of the Coherent Neutron Scattering Length of 3He

    Ketter, W.; Heil, W.; Badurek, G.; Baron, M.; Loidl, R.; Rauch, H.

    2005-01-01

    By means of neutron interferometry the s-wave neutron scattering length of the 3He nucleus was re-measured at the Institut Laue-Langevin (ILL). Using a skew symmetrical perfect crystal Si-interferometer and a linear twin chamber cell, false phase shifts due to sample misalignment were reduced to a negligible level. Simulation calculations suggest an asymmetrically alternating measuring sequence in order to compensate for systematic errors caused by thermal phase drifts. There is evidence in the experiment’s data that this procedure is indeed effective. The neutron refractive index in terms of Sears’ exact expression for the scattering amplitude has been analyzed in order to evaluate the measured phase shifts. The result of our measurement, b′c = (6.000 ± 0.009) fm, shows a deviation towards a greater value compared to the presently accepted value of b′c = (5.74 ± 0.07) fm, confirming the observation of the partner experiment at NIST. On the other hand, the results of both precision measurements at NIST and ILL exhibit a serious 12σ (12 standard uncertainties) deviation, the reason for which is not clear yet.

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

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

  14. Economic evaluation of D-T, D-3He, and catalyzed D-D fusion reactors

    Because the D-3He reaction generates no neutrons and the D-D reaction can use abundant fuel resources, these reactions are expected to be used in advanced fuel fusion reactors. Economic considerations and engineering problems are important for realizing such reactors as commercial plants. Therefore, we estimate and compare the cost of electricity (COE) from D-T, D-3He, and catalyzed D-D (cat D-D) fusion reactors. D-3He and cat D-D reactors have a low neutron wall load. Therefore, the D-3He reactor has no wall replacement cost. In addition, no tritium breeding system is needed for the D-3He reactor, but 3He gas is rare. Because the reaction rates of the D-3He and D-D reactions are less, D-3He and D-D reactors require highly efficient confinement properties and operation at high ion temperatures. Furthermore, the power densities of D-3He and D-D reactors are smaller than that of the D-T reactor; thus, D-3He and D-D reactors require a large plasma volume. Assuming a high ion temperature (= 60 keV) and high normalized beta (= 7-8), the COE of a D-3He reactor is expected to be similar to that of a D-T reactor. In terms of cost, cat D-D is disadvantageous in comparison with D-3He and D-T reactors. (author)

  15. Investigation of adsorption and wetting of 3He on cesium and cesiated glass

    Experiments have been carried out to investigate the binding of 3He on cesium substrates, using optical pumping to spin-polarize the atoms. The behavior of 3He on the walls at low temperature can be analyzed through the evolution of the nuclear magnetization of the sample. Preliminary results are presented, including: (1) adsorption studies of gaseous 3He on cesiated glass; (2) magnetic relaxation time of polarized liquid 3He on cesium and cesiated glass; (3) evidence for wetting of liquid 3He on cesium. 8 refs., 2 figs

  16. Realization of administration unit for {sup 3}He with gas recycling

    Gueldner, Manuela; Grossmann, Tino; Heil, Werner; Karpuk, Sergei; Otten, Ernst-Wilhelm; Salhi, Zahir [Institute of Physics, University Mainz (Germany); Becker, Stefan; Friesenecker, Andreas; Weiss, Patrick; Zentel, Juergen [ic-automation GmbH, Mainz (Germany); Gast, Klaus K.; Rivoire, Julien; Scholz, Alexander; Schreiber, Laura M.; Terekhov, Maxim; Wolf, Ursula [Department of Radiology, University Mainz (Germany)

    2011-07-01

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

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

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

  18. Nuclear relaxation of 3He at the surface of solid H2

    We present a detailed experimental study of the wall-relaxation on solid H2 surfaces of a dilute 3He gas, oriented by optical pumping. In these experiments, we measure the nuclear relaxation time of the whole sample of 3He which is directly related to the relaxation time Tsub(a) of the 3He atoms adsorbed on the solid H2 coating the sample walls. Measurement of T1 as a function of the temperature leads to an experimental determination of the adsorption energy of a 3He atom on solid H2: ΔW (3He/H2) = 12+-3 K. In addition, experiments have been done on D2 and Ne solid coatings leading to ΔW (3He/D2) = 20+-3 K and ΔW (3He/Ne) = 38+-5 K; all these experimental values are in good agreement with theoretical predictions

  19. Interferometric and acoustic measurements in superfluid (3)He-B and wetting studies in (3)He/(4)He mixtures. Doctoral thesis

    Alles, H.

    1995-06-22

    In this thesis work superfluid (3)He was investigated by two methods. First, ultrasonic experiments on (3)He-B were carried out using two coincident zero sound pulses. The second technique is optics, a novel method for ultra low temperatures. The developed method, two-beam interferometry, was employed successfully for studies of wetting phenomena in liquid (3)He/(4)He mixtures as well. This publication contains the results of a acoustic spectroscopy on (3)He-B. Most importantly, the real squashing collective mode (rsq) was excited by two simultaneous sound pulses yielding two phonon absorption (TPA). This nonlinear phenomenon was applied to study the dispersion relation of the rsq-mode. Zeeman splitting of the nonlinearly excited rsq-mode was investigated in a magnetic field. By means of TPA, an anomalous behavior was found also near the pair-breaking edge.

  20. Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases

    Bang, W; Bonasera, A; Quevedo, H J; Dyer, G; Bernstein, A C; Hagel, K; Schmidt, K; Gaul, E; Donovan, M E; Consoli, F; De Angelis, R; Andreoli, P; Barbarino, M; Kimura, S; Mazzocco, M; Natowitz, J B; Ditmire, T

    2013-01-01

    We report on experiments in which the Texas Petawatt laser irradiated a mixture of deuterium or deuterated methane clusters and helium-3 gas, generating three types of nuclear fusion reactions: D(d, 3He)n, D(d, t)p and 3He(d, p)4He. We measured the yields of fusion neutrons and protons from these reactions and found them to agree with yields based on a simple cylindrical plasma model using known cross sections and measured plasma parameters. Within our measurement errors, the fusion products were isotropically distributed. Plasma temperatures, important for the cross sections, were determined by two independent methods: (1) deuterium ion time-of-flight, and (2) utilizing the ratio of neutron yield to proton yield from D(d, 3He)n and 3He(d, p)4He reactions, respectively. This experiment produced the highest ion temperature ever achieved with laser-irradiated deuterium clusters.

  1. A possible in situ 3H and 3He source in Earth's interior: an alternative explanation of origin of 3He in deep Earth.

    Jiang, Songsheng; Liu, Jing; He, Ming

    2010-07-01

    Origin of (3)He in the Earth is a mystery. Lacking a production mechanism, scientists assume (3)He was trapped in the Earth, when the Earth was formed. In contrast to this assumption, we have found (3)He and (3)H concentrations in excess of the atmospheric values in the deep waters of the volcanic Lakes Pavin (France), Laacher (Germany) and Nemrut (Turkey). This paper reports the result of finding (3)H in these three volcanic lakes that appear to originate from the mantle. Because (3)H has a half-life of 12.3 years, this (3)H and the resulting (3)He must have formed recently in the mantle and not be part of a primordial reservoir. The nuclear reactions that generate tritium might be a source of "missing" energy in the interior of the Earth. PMID:20502855

  2. Energy dependence of the 6Li(π+,3He)3He reaction at 60, 75 and 90 MeV

    Differential cross sections for the pionic fission reaction 6Li(π+,3He)3He at T sub(π) = 60, 75 and 90 MeV have been measured for theta sub(c.m.) = 4l degrees. The energy dependence of the differential cross section is found to follow an exponential decrease with increasing incident pion energy and is compared with existing theoretical predictions

  3. A 3He Cryostat for Scientific Measurements in Pulsed High Magnetic Fields

    Wang, Shaoliang; Li, Liang; Liu, Mengyu; Zuo, Huakun; Peng, Tao

    A top loading 3He cryostat has been developed for scientific experiments with a 60 T pulsed magnetic field facility at Wuhan National High Magnetic Field Center. The cryostat consists of a 4He bath cryostat, a 3He insert and a closed circulation system for 3He gas handling. To eliminate the eddy current heating during the pulse, the tail of the 3He insert with a vacuum space at the bottom is made from fiberglass tubing coated with epoxy. The 3He bath is separated from the 4He bath with the vacuum space. The 4He bath cryostat provides cooling power to condense 3He gas by a neck tube on top of the tail. Experimental results have shown that the sample can be cooled down to 385 mK and kept cold for more than 150 second by one-shot cooling, which is sufficiently long for an experiment in a pulsed high magnetic field.

  4. Density dependence of the single particle kinetic energy in {sup 3}He-{sup 4}He

    Azuah, R.T. [Keele Univ. (United Kingdom). Dept. of Physics]|[Rutherford Appleton Lab., Chilton, Didcot (United Kingdom); Stirling, W.G. [Keele Univ. (United Kingdom). Dept. of Physics; Gibbs, M.R. [Keele Univ. (United Kingdom). Dept. of Physics; Sokol, P.E. [Dept. of Physics, Pennsylvania State Univ., University Park, PA (United States); Mayers, J. [Rutherford Appleton Lab., Chilton, Didcot (United Kingdom)

    1995-08-01

    We present inelastic neutron scattering measurements of liquid {sup 3}He-{sup 4}He mixtures at 1.5 K and at {sup 3}He concentrations of 0,15,40,70 and 100%. There is little apparent concentration dependence of the {sup 3}He kinetic energy, in disagreement with recent variational calculations for mixtures. The kinetic energy of the {sup 4}He component for the lower concentration mixtures is consistent with theoretical predictions. (orig.).

  5. Magnetization and Spin-Diffusion of Liquid 3He in Aerogel

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

    2004-01-01

    We report theoretical calculations of the normal-state spin diffusion coefficient of 3He in aerogel, including both elastic and inelastic scattering of 3He quasiparticles, and compare these results with experimental data for 3He in 98% porous silica aerogel. This analysis provides a determination of the elastic mean free path within the aerogel. Measurements of the magnetization of the superfluid phase provide a test of the theory of pairbreaking and magnetic response of low-energy excitation...

  6. Study of the /sup 50/V nucleus with the (/sup 3/He,d), (/sup 3/He,. cap alpha. ), (/sup 3/He,p), and (/sup 3/He,p. gamma. ) reactions. [Angular distribution, 13 and 22 MeV, analog states, DWBA, J,. pi. , spectroscopic factors, angular momentum, transitions

    Smith, J W

    1971-06-01

    The nucleus /sup 50/V with a ground-state configuration (..pi..f/sub 7/2/)/sup 3/(..nu..f/sub 7/2/)/sup -1/ was studied with the /sup 49/Ti(/sup 3/He,d)/sup 50/V, /sup 51/V)/sup 3/He,..cap alpha..)/sup 50/V, and /sup 48/Ti(/sup 3/He,p)/sup 50/V, and /sup 48/Ti(/sup 3/He,p..gamma..)/sup 50/V reactions induced by the /sup 3/He/sup + +/ beam from the tandem Van de Graaff at the Argonne National Laboratory. The angular distributions from (/sup 3/He,d), (/sup 3/He,..cap alpha..), and (/sup 3/He,p) reactions induced by 22-MeV /sup 3/He were studied with overall energy resolution widths of 20, 30, and 42 keV, respectively. The reactions (/sup 3/He,p) and (/sup 3/He,p..gamma..) were also studied at an incident energy of 13 MeV to obtain the ..gamma.. decay of /sup 50/V levels (including two 0/sup +/ isobaric analog states) in which the neutron-proton pair is transferred with zero angular momentum. The angular distributions of the charged-particle reactions were analyzed with the distorted-wave Born approximation (DWBA), and spectroscopic factors have been extracted for the one-nucleon transfer reactions. The two-nucleon transfer reaction (/sup 3/He,p) was analyzed with the DWBA on the assumption that the neutron-proton pair is transferred as a deuteron. The angular momentum L/sub np/ of the transferred deuteron is established for most of the levels, and the possibility that several levels might have spin and parity 1/sup +/ is discussed.

  7. Observation of Majorana Quasiparticles Surface States in Superfluid ${^3}$He-B by Heat Capacity Measurements

    Bunkov, Yury M.; Gazizulin, Rasul R.

    2016-01-01

    We report about direct measurements of heat capacity of Majorana quasiparticles in superfluid ${^3}$He-B which appear near the surface of the experimental bolometer on the coherence length ${\\xi}$. Two bolometers with different surface-to-volume ratios were used which allows us to have different calibrated contributions from Majorana quasiparticles to the ${^3}$He heat capacity. Estimations of possible impact of ${^3}$He layers adsorbed on the walls of the bolometer have been done.

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

    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)

  9. Study of the nuclear fusion in dμ3He complex

    Experimental study of the nuclear fusion reaction in charge-asymmetrical dμ3He complex (dμ3He → α (3.5 MeV) + p (14.64 MeV) is presented. The 14.64-MeV protons were detected by three pairs of Si(dE - E) telescopes placed around the cryogenic target filled with the D2 + 3He gas at 34 K. The 6.85 keV γ rays emitted during the de-excitation of the dμ3He complex were detected by a germanium detector. The measurements were performed at two D2 + 3He target densities, ψ = 0.0585 and ψ 0.169 (relative to liquid hydrogen density) with an atomic concentration of 3He c3He = 0.0469. The values of the effective rate of nuclear fusion in dμ3He was obtained for the first time: λf(tilde) (4.5-2.0+2.6) · 105s-1(ψ = 0.0585); λf(tilde) = (6.9-3.03.6) · 105s-1(ψ 0.168). The J =0 nuclear fusion rate in dμ3He was derived: λfJ=0 (9.7-2.6+5.7) · 105s-1 (ψ 0.0585); λfJ=0 = (12.4-5.4+6.5) · 105s-1 (ψ 0.168)

  10. Extraterrestrial 3He in marine polymetallic nodules: a potential method for measuring growth rate of nodules

    李延河; 宋鹤彬; 李金城

    2002-01-01

    The comparative measurements of helium isotope compositions between marine polymetallic nodules and their surrounding sediments, their magnetic fractions and bulk from C-C Zone of the East Pacific Basin are reported. The 4He content and 3He/4He ratio of polymetallic nodules and their surrounding sediments are extremely high; the 3He, 4He concentrations and most 3He/4He ratios of magnetic fractions in nodules and sediments are apparently higher than those in bulk. The helium isotope data points of nodules and sediments are all distributed along or closely to the mixing curve of the interplanetary dust particles (IDPs) and the terrigenous sediments in the chart of 3He-3He/4He. In the same sampling site, the 3He/4He ratios of nodules and their surrounding sediments are very similar, and the changes of both ratios are synchronous. It shows that the high 3He/4He ratios in nodules and sediments may all result from IDPs. So, if the flux of extraterrestrial 3He into the nodules and sediments is constant, the growth rate of polymetallic nodules and the sedimentation rate of sediments can be independently calculated according to the concentration of extraterrestrial 3He in nodules and sediments.

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

    The spin kinetics of 3He in contact with diamagnetic samples of inverse SiO2 opals and LaF3 nanopowders is investigated experimentally. The experimental results testify that the nuclear magnetic relaxation of adsorbed 3He occurs through the modulation of dipole-dipole interactions by quantum movements in a 2D layer while the relaxation of liquid 3He occurs through a spin-diffusion to the adsorbed layer. It is shown that the restricted geometry of diamagnetic nanoporous media influences the 3He relaxation process.

  12. DC discharge characteristics and fluorine atom yield in NF3/He

    Liping Duo; Shukai Tang; Haijun Yu; Jian Wang; Xiangde Min; Liucheng Li; Yuqi Jin; Bailing Yang; Fengting Sang

    2006-01-01

    @@ DC discharge characteristics of NF3/He have been investigated experimentally under different experimental conditions, for example, different electrode materials, separations, flow rates of the gas NF3 or He, and series resistances. The optimum discharge parameters and the fluorine atom yield from the DC discharge of NF3/He as function of load power are studied experimentally.

  13. A moving domain wall and order parameter orientation in 3He-B

    It is shown that movement of domain wall in the earlier considered two-domain structure in superfluid 3He β-phase eliminates the structure double degeneracy. It is suggested to use this fact for one-valued order parameter orientation in 3He-B

  14. First detection of 3He+ in the planetary nebula IC 418

    Guzman-Ramirez, L.; Rizzo, J. R.; Zijlstra, A. A.; García-Miró, C.; Morisset, C.; Gray, M. D.

    2016-07-01

    The 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in low-mass stars which evolve through the planetary nebula (PN) phase. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. We present the detection of the 3He+ emission line using the single dish Deep Space Station 63, towards the PN IC 418. We derived a 3He/H abundance in the range 1.74 ± 0.8 × 10-3 to 5.8 ± 1.7 × 10-3, depending on whether part of the line arises in an outer ionized halo. The lower value for 3He/H ratio approaches values predicted by stellar models which include thermohaline mixing, but requires that large amounts of 3He are produced inside low-mass stars which enrich the interstellar medium (ISM). However, this overpredicts the 3He abundance in H II regions, the ISM, and protosolar grains, which is known to be of the order of 10-5. This discrepancy questions our understanding of the evolution of the 3He, from circumstellar environments to the ISM.

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

    Experiments involving neutron scattering by 3He 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 3He and 4He: a single crystal of helium have been obtained within a sintered metal in which the pore size is less than a micron are presented

  16. Possible Dimensional Crossover to 1D of ^3He Fluid in Nanochannels Observed in Susceptibilities

    Matsushita, Taku; Kurebayashi, Katsuya; Shibatsuji, Ryosuke; Hieda, Mitsunori; Wada, Nobuo

    2016-05-01

    Dimensional crossover to the one-dimensional (1D) state from higher dimensions has been studied for dilute ^3He fluid adsorbed in 2.4 nm ^4He-preplated nanochannels, by susceptibility measurements down to 70 mK using 4.29 MHz nuclear magnetic resonance. In nanochannels, since energy states of ^3He motion perpendicular to the channel axis are discrete, a genuine 1D ^3He fluid is expected when the Fermi energy is less than the first excitation Δ _{01} for azimuthal motion. The susceptibilities χ above 0.3 K show the Curie-law susceptibilities independent of the ^3He density, which are characteristic of nondegenerate fluid in higher dimensions. With decreasing the temperature, a significant reduction of χ T was observed from about 0.3 K for all ^3He densities. It is considered to be due to the dimensional crossover below Δ _{01}˜ 0.5 K to the 1D ^3He state in the semi-degenerate regime above the Fermi temperature. In the 1D state at lower temperatures, T-independent χ were observed for ^3He of 0.019 layers below 0.1 K. It suggests that the 1D ^3He fluid enters the quantum degenerate regime.

  17. The ground state energy of 3He droplet in the LOCV framework

    The (extended) lowest order constrained variational method was used to calculate the ground state energy of liquid helium 3 (3He) 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 3He atoms are needed to get the bound state for 3He liquid droplet. Depending on the choice of the density profiles and the atomic radius of 3He, the above estimate can increase to 300. Our calculated ground state energy and the number of atoms in liquid 3He 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.

  18. First measurement of the helicity dependence of 3He photoreactions in the Δ(1232 resonance region

    Costanza Susanna

    2014-03-01

    Full Text Available The first measurement of the helicity dependence for several photo-reaction channels on 3He was carried out in the photon energy range between 150 and 500 MeV at the MAMI accelerator (Mainz. The experiment used the large acceptance Crystal Ball spectrometer, complemented by charged particle and vertex detectors, a circularly polarised tagged photon beam and a longitudinally polarised high-pressure 3He gas target. Results of the helicity dependent total inclusive photoabsorption cross section on 3He and of both the unpolarised and polarised partial cross sections for the pion photoproduction channels γ 3He → πX and for the γ 3He → ppn channel, measured for the first time at MAMI, will be shown. They can also be found in [1].

  19. Burnup of fusion produced tritons and 3He ions in PLT and PDX

    The d(d,p)t and d(d,n)3He fusion reactions produce 1 MeV tritons and 0.8 MeV 3He ions which can subsequently undergo d(t,n)α and d(3He,p)α fusion reactions. The magnitude of this triton and 3He ion burnup was measured on the PLT and PDX tokamaks by detection of the 14 MeV neutron and 15 MeV proton emission. In discharges with B/sub phi/ greater than or equal to 2 T, the measured 3He burnup agrees well with predictions based on classical theories of ion confinement and slowing down, while the triton burnup was about four times lower than theoretically predicted. In discharges with weaker toroidal fields, the burnup of both ions fell by more than a factor of ten

  20. Electron bubbles and Weyl fermions in chiral superfluid 3He-A

    Shevtsov, Oleksii; Sauls, J. A.

    2016-08-01

    Electrons embedded in liquid 3He form mesoscopic bubbles with large radii compared to the interatomic distance between 3He atoms, voids of Nbubble≈200 3He atoms, generating a negative ion with a large effective mass that scatters thermal excitations. Electron bubbles in chiral superfluid 3He-A also provide a local probe of the ground state. We develop a scattering theory of Bogoliubov quasiparticles by negative ions embedded in 3He-A that incorporates the broken symmetries of 3He-A , particularly broken symmetries under time reversal and mirror symmetry in a plane containing the chiral axis l ̂. Multiple scattering by the ion potential, combined with branch conversion scattering by the chiral order parameter, leads to a spectrum of Weyl fermions bound to the ion that support a mass current circulating the electron bubble—a mesoscopic realization of chiral edge currents in superfluid 3He-A films. A consequence is that electron bubbles embedded in 3He-A acquire angular momentum, L ≈-(Nbubble/2 ) ℏ l ̂ , inherited from the chiral ground state. We extend the scattering theory to calculate the forces on a moving electron bubble, both the Stokes drag and a transverse force, FW=e/c v ×BW , defined by an effective magnetic field, BW∝l ̂ , generated by the scattering of thermal quasiparticles off the spectrum of Weyl fermions bound to the moving ion. The transverse force is responsible for the anomalous Hall effect for electron bubbles driven by an electric field reported by the RIKEN group. Our results for the scattering cross section, drag, and transverse forces on moving ions are compared with experiments and shown to provide a quantitative understanding of the temperature dependence of the mobility and anomalous Hall angle for electron bubbles in normal and superfluid 3He-A . We also discuss our results in relation to earlier work on the theory of negative ions in superfluid 3He.

  1. 3He and BF3 Neutron Detector Pressure Effect and Model Comparison

    Paper for SORMA conference Radiation detection systems for homeland security applications must possess the capability of detecting both gamma rays and neutrons. The radiation portal monitor (RPM) systems that are currently deployed use a plastic scintillator for detecting gamma rays and 3He gas-filled proportional counters for detecting neutrons. Proportional counters filled with 3He are the preferred neutron detectors for use in RPMs because 3He has a large neutron cross section, is relatively insensitive to gamma-rays, is neither toxic nor corrosive, can withstand extreme environments, and can be operated at a lower voltage than some of the alternative proportional counters. The amount of 3He required for homeland security and science applications has depleted the world supply and there is no longer enough available to fill the demand. Thus, alternative neutron detectors are being explored. Two possible temporary solutions that could be utilized while a more permanent solution is being identified are reducing the 3He pressure in the proportional counters and using boron trifluoride (BF3) gas-filled proportional counters. Reducing the amount of 3He required in each of the proportional counters would decrease the rate at which 3He is being used, not enough to solve the shortage but perhaps enough to increase the amount of time available to find a working replacement. BF3 is not appropriate for all situations as these detectors are less sensitive than 3He, BF3 gas is corrosive, and a much higher voltage is required than what is used with 3He detectors. Measurements of the neutron detection efficiency of 3He and BF3 as a function of tube pressure were made. The experimental results were also used to validate models of the RPMs.

  2. 3He and BF3 neutron detector pressure effect and model comparison

    Radiation detection systems for homeland security applications must possess the capability of detecting both gamma rays and neutrons. The radiation portal monitor systems that are currently deployed use a plastic scintillator for detecting gamma rays and 3He gas-filled proportional counters for detecting neutrons. Proportional counters filled with 3He are the preferred neutron detectors for use in radiation portal monitor systems because 3He has a large neutron cross-section, is relatively insensitive to gamma-rays, is neither toxic nor corrosive, can withstand extreme environments, and can be operated at a lower voltage than some of the alternative proportional counters. The amount of 3He required for homeland security and science applications has depleted the world supply and there is no longer enough available to fill the demand. Thus, alternative neutron detectors are being explored. Two possible temporary solutions that could be utilized while a more permanent solution is being identified are reducing the 3He pressure in the proportional counters and using boron trifluoride gas-filled proportional counters. Reducing the amount of 3He required in each of the proportional counters would decrease the rate at which 3He is being used; not enough to solve the shortage, but perhaps enough to increase the amount of time available to find a working replacement. Boron trifluoride is not appropriate for all situations as these detectors are less sensitive than 3He, boron trifluoride gas is corrosive, and a much higher voltage is required than what is used with 3He detectors. Measurements of the neutron detection efficiency of 3He and boron trifluoride as a function of tube pressure were made. The experimental results were also used to validate models of the radiation portal monitor systems.

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

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

    2016-03-01

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

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

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

    2016-01-01

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

  5. Evidence of Cluster Structure of $^9$Be from $^3$He+$^9$Be Reaction

    Lukyanov, S M; Naumenko, M A; Xu, Yi; Trzaska, W H; Burjan, V; Kroha, V; Mrazek, J; Glagolev, V; Piskoř, Š; Voskoboynik, E I; Khlebnikov, S V; Penionzhkevich, Yu E; Skobelev, N K; Sobolev, Yu G; Tyurin, G P; Kuterbekov, K; Tuleushev, Yu

    2015-01-01

    The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a $^{9}$Be target with a $^3$He beam at an incident energy of 30 MeV. Angular distributions for $^9$Be($^3$He,$^3$He)$^{9}$Be, $^9$Be($^3$He,$^4$He)$^{8}$Be, $^9$Be($^3$He,$^5$He)$^{7}$Be, $^9$Be($^3$He,$^6$Li)$^6$Li and $^9$Be($^3$He,$^5$Li)$^7$Li reaction channels were measured. Experimental angular distributions for the corresponding ground states (g.s.) were analysed within the framework of the optical model, the coupled-channel approach and the distorted-wave Born approximation. Cross sections for channels leading to unbound $^5$He$_{g.s.}$, $^5$Li$_{g.s.}$ and $^8$Be systems were obtained from singles measurements where the relationship between the energy and the scattering angle of the observed stable ejectile is constrained by two-body kinematics. Information on the cluster structure of $^{9}$Be was obtained from the transfer channels. It was concluded that cluster transfer is an important mechanism in t...

  6. First Detection of $^3$He$^+$ in the Planetary Nebula IC$\\,$418

    Guzman-Ramirez, L; Zijlstra, A A; García-Miró, C; Morisset, C; Gray, M D

    2016-01-01

    The $^3$He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in low-mass stars which evolve through the planetary nebula (PN) phase. $^3$He abundances in PNe can help test models of the chemical evolution of the Galaxy. We present the detection of the $^3$He$^+$ emission line using the single dish Deep Space Station 63, towards the PN IC$\\,$418. We derived a $^3$He/H abundance in the range 1.74$\\pm$0.8$\\times$10$^{-3}$ to 5.8$\\pm$1.7$\\times$10$^{-3}$, depending on whether part of the line arises in an outer ionized halo. The lower value for $^3$He/H ratio approaches values predicted by stellar models which include thermohaline mixing, but requires that large amounts of $^3$He are produced inside low-mass stars which enrich the interstellar medium (ISM). However, this over-predicts the $^3$He abundance in HII regions, the ISM, and proto-solar grains, which is known to be of the order of 10$^{-5}$. This discrepancy questi...

  7. Multi-spacecraft observations of recurrent {sup 3}He-rich solar energetic particles

    Bučík, R.; Innes, D. E.; Mall, U.; Korth, A. [Max-Planck-Institut für Sonnensystemforschung, D-37077 Göttingen (Germany); Mason, G. M. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Gómez-Herrero, R., E-mail: bucik@mps.mpg.de [Space Research Group, University of Alcalá, E-28871 Alcalá de Henares (Spain)

    2014-05-01

    We study the origin of {sup 3}He-rich solar energetic particles (<1 MeV nucleon{sup –1}) that are observed consecutively on STEREO-B, Advanced Composition Explorer (ACE), and STEREO-A spacecraft when they are separated in heliolongitude by more than 90°. The {sup 3}He-rich period on STEREO-B and STEREO-A commences on 2011 July 1 and 2011 July 16, respectively. The ACE {sup 3}He-rich period consists of two sub-events starting on 2011 July 7 and 2011 July 9. We associate the STEREO-B July 1 and ACE July 7 {sup 3}He-rich events with the same sizeable active region (AR) producing X-ray flares accompanied by prompt electron events, when it was near the west solar limb as seen from the respective spacecraft. The ACE July 9 and STEREO-A July 16 events were dispersionless with enormous {sup 3}He enrichment, lacking solar energetic electrons and occurring in corotating interaction regions. We associate these events with a small, recently emerged AR near the border of a low-latitude coronal hole that produced numerous jet-like emissions temporally correlated with type III radio bursts. For the first time we present observations of (1) solar regions with long-lasting conditions for {sup 3}He acceleration and (2) solar energetic {sup 3}He that is temporarily confined/re-accelerated in interplanetary space.

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

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

    2011-01-01

    The strong-interaction shift of kaonic 3He and 4He 2p states was measured using gaseous targets for the first time in the SIDDHARTA experiment. The determined shift of kaonic 4He is much smaller than the values obtained in the experiments performed in 70's and 80's. Thus, the problems in kaonic helium (the "kaonic helium puzzle") was definitely solved by our measurements. The first observation of the kaonic 3He X-rays was also achieved. The shift both of kaonic 3He and 4He was found to be as small as a few eV.

  9. Exchange of np-pair in elastic p3He-backscattering at intermidiate energies

    The contribution of loop Feynmann diagrams, describing the np-pair transfer in backward elastic p3He scattering, has been investigated in the framework of the three-dimensional diagram approach at incident energies of 0.2-1.7 GeV. It is shown that the sum of discussed diagrams is equivalent to the Born approximation in NN-interaction potentials. The numerical calculations performed using the five-channel Faddeev wave function of3He show that the sequentional n-p transfer dominates and its amplitude is rather weakly sensitive to the D-components of the 3He wave function and relativistic corrections. 26 resf., 3 figs

  10. Static aspects of the fission and fusion of liquid 3He drops

    Using an effective 3He-3He interaction, the fission and fusion of 3He 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

  11. Study of neutron spin structure functions at low Q2 with polarized 3He

    The recently completed experiment E94-010 at Jefferson Lab studies the neutron spin structure functions at low momentum transfer (Q2) values. Using a polarized 3 He target and polarized electron beam, we have measured the asymmetries and cross sections for 3He(e,e') from the elastic to the deep inelastic region. The covered Q2 ranges from 0.03 to 1.1 GeV2. From the data, the Q2 evolution of the spin structure functions for 3He and neutron, and of the Gerasimov-Drell-Hearn (GDH) sum rule has been studied, and the preliminary results are presented

  12. What can superconductivity learn from quantized vorticity in 3He superfluids?

    In 3He superfluids quantized vorticity can take many different forms: It can appear as distributed periodic textures, as sheets, or as lines. In the anisotropic 3He-A phase in most cases the amplitude of the order parameter remains constant throughout the vortex structure and only its orientation changes in space. In the quasi-isotropic 3He-B phase vortex lines have a hard core where the order parameter has a reduced, but finite amplitude. The different structures have been firmly identified, based on both measurement and calculation. What parallels can be drawn from this information to the new unconventional superconductors or Bose-Einstein condensates? (orig.)

  13. Study on (n3, He) fusion reactions cross sections using optical model

    Non-elastic cross-sections have been calculated by using optical model for (n3, He) reactions at 22.5 MeV energy. The empirical formula including optical model non-elastic effects by fitting two parameters for the (n3, He) reaction cross-sections have been suggested. Reaction Q-values depending on the asymmetry term effect for the (n3, He) reaction have been investigated. The obtained cross-section formula with new coefficients has been compared with the experimental data and discussed. It has seen that the fit of formula in this paper is in good agreement with the experimental data

  14. Measurements of the structure and nucleation of vorticity in the (3)He superfluids. Doctoral thesis

    Parts, U.

    1995-10-01

    This thesis reports experiments on rotating superfluid 3He, which were performed in the Low Temperature Laboratory during the period 1991-94, and which are published in a series of original publications. Rotation is particularly useful for creating various types of topological objecs, e.g. quantized vortex lines, in large quantities for systematic investigation. The author`s method to study them is the nuclear magnetic resonance (NMR) technique, which has been an important experimental tool in various fields of physics for about fifty years. In the case of superfluid 3He, NMR provides direct information on the spatial distribution of the order parameter field. Both superfluid phases of 3He, the A- and the B-phase, have been under investigation in this thesis work. In 3He-B the main concern has been the nucleation of singular vortices. This process involves an energy barrier, similar to a first order phase transition.

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

    The author measured the specific heat of dilute 3He-4He 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 3He-4He mixtures. To reach the required temperature range for our experiments a 4He circulating 3He-4He dilution refrigerator has been constructed. The results confirm the deviation of the 3He contribution to the specific heat from the ideal Fermi gas behaviour. (Auth.)

  16. Preconceptual engineering design for the APT 3He Target/Blanket concept

    A preconceptual engineering design has been developed for the 3He 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 3He 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 3He gas; containment of the gas and radionuclides; remote handling; material compatibility; minimization of 3He, D2O, and activated waste; modularity; and manufacturability. The design provides a basis for estimating the cost to implement the system

  17. The ion optics of a miniature 3He/4He mass spectrometer of high resolution

    To measure the isotopic abundance ratio of 3He and 4He in samples by mass spectrometers is an important detection mean for helium isotope geochemistry research. A symmetrically arranged tandem 3He/4He mass spectrometer is described in the paper. The front stage, used to analyse 3He (including HD and H3) and 4He, is a homogeneous analysing magnet with a bending angle of 90 deg and a bending radius of 6 cm. The end stage, used to analyse 3He, HD and H3, is a non-homogeneous analysing magnet with a bending angle of 180 deg, a bending radius of 15 cm and a magnetic field gradient of 0.75. Because of the use of the non-zero second order coefficient β and curved entrance face of the later magnet for eliminating second order aberrations, the resolving power of the system is notably improved, and theoretically reaches about 3800

  18. Discovery of superfluid 3He phases wins 1996 nobel prize in physics

    The 1996 Nobel prize in physics was awarded to David M. Lee, Douglas D. Osheroff and Robert C. Richardson for their discovery of superfluidity in 3He in 1971. A short account of the discovery and its importance is given

  19. Cryopol: a superconducting magnetostatic cavity for a sup 3 He neutron spin filter

    Dreyer, J; Bourgeat-Lami, E; Lelievre-Berna, E; Pujol, S; Thomas, F; Thomas, M; Tasset, F

    2000-01-01

    We present a device called 'Cryopol' that provides a clean magnetic environment for a sup 3 He spin filter cell, even in the presence of strong magnetic stray fields like those of a superconducting magnet.

  20. Regional Ventilation Changes in Severe Asthma after Bronchial Thermoplasty with 3He MR Imaging and CT

    Thomen, Robert P.; Sheshadri, Ajay; Quirk, James D.; Kozlowski, Jim; Ellison, Henry D.; Szczesniak, Rhonda D.; Castro, Mario; Woods, Jason C.

    2014-01-01

    We quantified regional lung ventilation in healthy volunteers and patients with severe asthma (both before and after thermoplasty) at the level of individual bronchopulmonary segments by using a combination of 3He MR imaging and CT.

  1. New data and evaluation of sup 3 He-induced nuclear reactions on Cu

    Tarkanyi, F; Takács, S; Al-Abyad, M; Mustafa, M G; Shubin, Y; Zhuang, Y

    2002-01-01

    Excitation functions of sup n sup a sup t Cu( sup 3 He, x) sup 6 sup 6 Ga, sup n sup a sup t Cu( sup 3 He, x) sup 6 sup 7 Ga, sup n sup a sup t Cu( sup 3 He, x) sup 6 sup 3 Zn and sup n sup a sup t Cu( sup 3 He, x) sup 6 sup 5 Zn nuclear reactions were measured up to 36 MeV using stacked foil irradiation arrangement and activation technique. The results were compared with compiled literature data. The status of the experimental database was investigated with the goal to produce recommended values for different applications. The application of the deduced data in the field of beam monitoring and thin layer activation is discussed.

  2. Ignition analysis for D plasma with non-Maxwellian 3He minority in fusion reactors

    Possible fusion reactivity enhancement due to 3He minority ICRF heating in D-3He toroidal plasma is demonstrated in present numerical simulations. On this purpose the particle code based on test-particle approach is developed. This code solves guiding center equations for 3He ions in toroidal magnetic field including Coulomb collisions of these ions with the background deuterons and electrons. A simple Monte Carlo model for ICRF heating is implemented in this code as well. The transformation of 3He distribution function from Maxwellian to non-Maxwellian due to heating plays the key role for reactivity enhancement. The formation of significant energetic tail gives rise to the reactivity enhancement. This is an important issue for the performance of fusion reactors with minority heating of ICRF. (author)

  3. Isospin effects in the exclusive dp -> 3He{\\pi}+{\\pi}- reaction

    Mielke, M; Chiladze, D; Dymov, S; Fritzsch, C; Gebel, R; Goslawski, P; Hartmann, M; Kacharava, A; Khoukaz, A; Kulessa, P; Lorentz, B; Mersmann, T; Mikirtychiants, S; Ohm, H; Papenbrock, M; Rausmann, T; Serdyuk, V; Ströher, H; Täschner, A; Valdau, Y; Wilkin, C

    2014-01-01

    The differential cross section for the exclusive dp -> 3He{\\pi}+{\\pi}- reaction has been measured with high resolution and large statistics over a large fraction of the backward 3He hemisphere at the excess energy 265 MeV using the COSY-ANKE magnetic spectrometer. Though the well-known ABC enhancement is observed in the {\\pi}+{\\pi}- spectrum, the differences detected between the {\\pi}+3He and {\\pi}-3He invariant-mass distributions show that there must be some isospin-one {\\pi}{\\pi} production even at relatively low excess energies. The invariant-mass differences are modeled in terms of the sequential decay N*(1440) -> Delta(1232){\\pi} -> N{\\pi}{\\pi}.

  4. Generalized parton distributions of 3He and the neutron orbital structure

    Rinaldi, Matteo; Scopetta, Sergio

    2013-01-01

    The two leading twist, quark helicity conserving generalized parton distributions (GPDs) of 3He, accessible, for example, in coherent deeply virtual Compton scattering (DVCS), are calculated in impulse approximation (IA). Their sum, at low momentum transfer, is found to be largely dominated by the neutron contribution, so that 3He is very promising for the extraction of the neutron information. Anyway, such an extraction could be not trivial. A technique, able to take into account the nuclear...

  5. Ionization of polarized 3He+ ions in EBIS trap with slanted electrostatic mirror.

    Pikin,A.; Zelenski, A.; Kponou, A.; Alessi, J.; Beebe, E.; Prelee, K.; Raparia, D.

    2007-09-10

    Methods of producing the nuclear polarized {sup 3}He{sup +} ions and their ionization to {sup 3}H{sup ++} in ion trap of the electron Beam Ion Source (EBIS) are discussed. Computer simulations show that injection and accumulation of {sup 3}He{sup +} ions in the EBIS trap with slanted electrostatic mirror can be very effective for injection times longer than the ion traversal time through the trap.

  6. Improved Technique for Measurement of Regional Fractional Ventilation by Hyperpolarized 3He MRI

    Emami, Kiarash; Kadlecek, Stephen J.; Woodburn, John M.; Zhu, Jianliang; Yu, Jiangsheng; Vahdat, Vahid; Pickup, Stephen; Ishii, Masaru; Rizi, Rahim R.

    2010-01-01

    Quantitative measurement of regional lung ventilation is of great significance in assessment of lung function in many obstructive and restrictive pulmonary diseases. A new technique for regional measurement of fractional ventilation using hyperpolarized 3He MRI is proposed, addressing the shortcomings of an earlier approach that limited its use to small animals. The new approach allows for the acquisition of similar quantitative maps over a shortened period and requires substantially less 3He...

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

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

  8. Validity of the evidence for a central depression in the charge density of 3He

    The derivation of proton and neutron charge densities from experimentally obtained form factors is considered. The meson exchange current contribution to the 3He charge form factor for three models of neutron and proton charge form factors is calculated and it is shown that it is not valid to use the short range behavior of nucleon charge density to deduce information on the structure of 3He

  9. Contribution to the study of a helium dilution refrigerator with a 3He - 4He mixture

    New concepts to improve the conditions of operation of a helium dilution refrigerator with 3He additions in 4He are presented. The sealing of several circuits including heat exchangers is studied. A cryostat operating without a 3He condensation system is developed. The cryostat allows temperatures as low as 40 mK to be reached and is small enough to be transportable. The whole system was designed for neutron diffraction studies. The utilization of sintered silver powder heat exchangers is considered

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

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

    2012-02-01

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

  11. Electropion production in 3He determined by measuring the triton recoil cross section

    The 3He(e,T) π+,e' cross section has been measured as a function of incident electron energy, triton recoil energy and angle. The experiment corresponds to excitation energies near 20 MeV above pion threshold. Comparison is made with a theory including all partial waves using Gaussian and Irving-Gunn ground states for 3He. The forward peaking approximation is also discussed

  12. 3He(e,d)e'p isochromats and angular distribution measurements

    An angular distribution and isochromats for the reaction 3He(e,d)e'p were measured to determine the importance of E2 strength near the peak of the 3He(#betta#,d)p cross section. The angular distribution was analyzed using both a complete and approximate virtual photon spectrum. The isochromats were compared to a plane wave model prediction and least squares fitted to determine the relative amounts of E1 and E2 strength

  13. Hyperpolarized 3He magnetic resonance imaging: Preliminary evaluation of phenotyping potential in chronic obstructive pulmonary disease

    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 (3He) magnetic resonance imaging (MRI) functional and structural measurements and to explore the potential role for 3He 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, 1H MRI and hyperpolarized 3He MRI at 3.0 T. 3He ventilation defect percent (VDP) was generated from 3He static ventilation images and 1H thoracic images and the 3He 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 3He 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 3He MRI to categorize or phenotype COPD ex-smokers, providing good evidence of feasibility for larger prospective studies.

  14. First doubly polarised photoproduction on 3He at the photon beam of MAMI

    A first experiment with a polarised 3He 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 3He 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 3He. 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 3He 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 3He 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 3He compared with several theoretical models will also be presented. (orig.)

  15. Possibilities for breakeven and ignition of D-3He fusion fuel in a near term tokamak

    The recent realization that the moon contains a large amount of the isotope 3He has rekindled interest in the D-3He fuel cycle. In this study we consider the feasibility of investigating D-3He reactor plasma conditions in a tokamak of the NET/INTOR class. We have found that, depending on the energy confinement scaling law, energy breakeven may be achieved without significant modification to the NET design. The best results are for the more optimistic ASDEX H-mode scaling law. Kaye-Goldston scaling with a modest improvement due to the H-mode is more pessimistic and makes achieving breakeven more difficult. Significant improvement in Q (ratio of the fusion power to the injected power), or the ignition margin, can be achieved by taking advantage of the much reduced neutron production of the D-3He fuel cycle. Removal of the tritium producing blanket and replacing the inboard neutron shield by a thinner shield optimized for the neutron spectrum in D-3He allows the plasma to be increased without changing the magnetic field at the toroidal field magnet. This allows the plasma to achieve higher beta and Q values up to about 3. The implications of D-3He operation for fast ion loss, neutron shielding, heat loads on the first wall and divertor, plasma refuelling, changes to the poloidal field coil system, and pumping of the helium from the vacuum chamber are considered in the report. (orig.)

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

    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

  17. Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

    Purpose: To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium (3He)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT). Materials and methods: Twenty-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP 3He-MRI and MSCT. Mean age was 55 (±12) years, 18 female and 9 male. Mean ADC from 3He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test. Results: Mean ADC and standard deviation values were 0.392 ± 0.119 cm2/s for the established emphysema group and 0.216 ± 0.046 for the pre-clinical emphysema group. MSCT values for the established emphysema group and pre-clinical emphysema group were: EI (%) 11 ± 12 and 0.4 ± 0.6, respectively; 15th percentile (Hounsfield Units (HU)), -956 ± 25 and -933 ± 13, respectively and MLD (HU) -877 ± 20 and -863 ± 15, respectively. Correlations between mean ADC and EI and 15th percentile were both r = 0.90 and for MLD r = 0.59. There was higher correlation between mean ADC and %predicted DLCO (r = 0.90) than between EI and %predicted DLCO (r = 0.76). Conclusion: HP 3He-MRI correlates well with density measurements from MSCT and agrees better than MSCT with %predicted DLCO which is the PFT most related to emphysema.

  18. The $^{150}$Nd($^3$He,$t$) and $^{150}$Sm($t$,$^3$He) reactions with applications to $\\beta\\beta$ decay of $^{150}$Nd

    Guess, C J; Akimune, H; Algora, A; Austin, Sam M; Bazin, D; Brown, B A; Caesar, C; Deaven, J M; Ejiri, H; Estevez, E; Fang, D; Faessler, A; Frekers, D; Fujita, H; Fujita, Y; Fujiwara, M; Grinyer, G F; Harakeh, M N; Hatanaka, K; Herlitzius, C; Hirota, K; Hitt, G W; Ishikawa, D; Matsubara, H; Meharchand, R; Molina, F; Okamura, H; Ong, H J; Perdikakis, G; Rodin, V; Rubio, B; Shimbara, Y; Süsoy, G; Suzuki, T; Tamii, A; Thies, J H; Tur, C; Verhanovitz, N; Yosoi, M; Yurkon, J; Zegers, R G T; Zenihiro, J

    2011-01-01

    The $^{150}$Nd($^3$He,$t$) reaction at 140 MeV/u and $^{150}$Sm($t$,$^3$He) reaction at 115 MeV/u were measured, populating excited states in $^{150}$Pm. The transitions studied populate intermediate states of importance for the (neutrinoless) $\\beta\\beta$ decay of $^{150}$Nd to $^{150}$Sm. Monopole and dipole contributions to the measured excitation-energy spectra were extracted by using multipole decomposition analyses. The experimental results were compared with theoretical calculations obtained within the framework of Quasiparticle Random-Phase Approximation (QRPA), which is one of the main methods employed for estimating the half-life of the neutrinoless $\\beta\\beta$ decay ($0\

  19. Development of a 3He/Xe gas scintillation counter to measure the 3He(n,p)T cross section in the intermediate energy range

    A 3He/Xe gas scintillation counter has been developed for measuring the neutron energy range from thermal to 3 MeV. Great effort was concentrated on improving the detector design to optimize light production and collection to improve the energy resolution which is primarily controlled by photon statistics. The detectors were tested using a 238Pu alpha-particle source, a thermal neutron beam from the NBS reactor, and the white-neutron spectrum from the NBS linac. The detector measures an energy resolution of 17 % (FWHM) for the 3He(n,p)T reaction at 2.0 MeV which is sufficient for cross section measurement. (author)

  20. Development of a 3He/Xe gas scintillation counter to measure the 3He(n,p)T cross section in the intermediate energy range

    A 3He/Xe gas scintillation counter has been developed for measuring the neutron energy range from thermal to 3 MeV. Great effort was concentrated on improving the detector design to optimize light production and collection to improve the energy resolution which is primarily controlled by photon statistics. The detectors were tested using a 238Pu alpha-particle source, a thermal neutron beam from the NBS reactor, and the white-neutron spectrum from the NBS linac. The detector measures an energy resolution of 17% (FWHM) for the 3He(n,p)T reaction at 2.0 MeV which is sufficient for cross section measurement. 12 refs., 8 figs

  1. Forward-angle 3He(e,e'π+-) coincident electroproduction and the search for Δ's in the ground state of 3He

    Forward-angle coincident electroproduction cross sections of charged pions from 3He have been measured at the cw electron accelerator MAMI. The overall features of the data are reproduced in terms of a microscopic model, including pole terms, final state rescattering and produced and preformed Δ resonances. Separation of the cross section into its longitudinal and transverse parts was performed for the first time. (K.A.)

  2. Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

    Diaz, Sandra; Casselbrant, Ingrid; Piitulainen, Eeva;

    2008-01-01

    -seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP (3)He-MRI and MSCT. Mean age was 55 (+/-12) years, 18 female and 9 male. Mean ADC from (3)He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values...... from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test. RESULTS: Mean ADC and standard deviation values were 0.392+/-0.119 cm(2)/s for the established emphysema group and 0....... Correlations between mean ADC and EI and 15th percentile were both r=0.90 and for MLD r=0.59. There was higher correlation between mean ADC and %predicted DLCO (r=0.90) than between EI and %predicted DLCO (r=0.76). CONCLUSION: HP (3)He-MRI correlates well with density measurements from MSCT and agrees better...

  3. Photodisintegration of /sup 3/H and /sup 3/He. [Threshold to 25 MeV

    Faul, D.D.

    1980-09-01

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

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

    Sulkosky, Vincent A. [Univ. of Virginia, Charlottesville, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-03-01

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

  5. Orbital angular momentum and orbital dynamics: /sup 3/He-A and the Bose liquid

    Volovik, G.E.; Mineev, V.P.

    1981-09-01

    General expressions for the superfluid current and the orbital angular momentum in a superfluid liquid with the structure of the A phase of /sup 3/He at T = 0 are derived which go over in the limit ..delta..>>epsilon-c/sub F/ into the corresponding expressions for a Bose liquid consisting of molecules with spin h1. It is shown that the local intrinsic angular momentum in /sup 3/He-A, unlike the corresponding quantity in a Bose liquid, is defined only in variations, and its spontaneous part is small on account of the smallness of (..delta../epsilon-c/sub F/)/sup 2/. The Lagrangian formalism is used to construct the nonlinear orbital dynamics of /sup 3/He-A at T = 0. It is shown that in the presence of textures in the l-vector field the dynamical equations are not Galilean invariant, which is another manifestation of the difference between /sup 3/He-A and a Bose liquid. The noninvariance stems from the fact that, because of the absence of a gap in the excitation spectrum, the nonsingular textures in /sup 3/He-A possess normal momenta, as a result of which the normal-component density is nonzero even at T = 0, and the velocity of the normal component does not drop out of the dynamical equations.

  6. /sup 3/He-A versus bose liquid: orbital angular momentum and orbital dynamics

    Volovik, G.S.; Mineev, V.P. (AN SSSR, Moscow. Inst. Teoreticheskoj Fiziki)

    1981-09-01

    At T=0 are obtained general expressions for the superfluid current and orbital angular momentum in a superfluid liquid with the structure of the /sup 3/He A-phase which in the limit ..delta..<3/He-A is not a total differential and its spontaneous part is small since (..delta../epsilonsub(F))sup(2)<<1. Nonlinear orbital dynamics of He/sup 3/He-A at T=0 is obtained on the basis of the Lagrangian formalism. It is shown that in the presence of textures in the field of the vector I the equations of dynamics do not meet the requirements of Galilean invariance which also displays the difference of /sup 3/He-A from the Bose liquid. The noninvariance is associated with the fact that due to the absence of the gap in the excitation spectrum nonsingular textures in /sup 3/He-A have a normal momentum as a result of which even at T=0 the density of the normal component does not become equal to zero and the velocity of the normal component is retained in the equations of dynamics.

  7. 3He in extreme conditions: from fundamental physics to applications in astrophysics

    This work is composed of three different parts: in the first part, a long term project on a dark matter detector prototype based on superfluid 3He (ULTIMA) is continued, and several precious observations for the operation of a future large detector are presented. The importance of covering the bolometer cell surfaces with 4He, as solid layers of 3He drastically reduce the sensitivity, is demonstrated. The systematic measurement of the influence of the magnetic field on the energy calibration is presented. Most importantly, a difference of the pulse shape for different incident particles has been observed and studied. This is likely to provide a powerful discrimination criterion for a future dark matter detector. In a second part, the existing setup is used to do measurements on fundamental 3He physics. First, the heat capacity of adsorbed layers of 3He is measured at ultra low temperatures and in the presence of magnetic fields. Secondly, the fast transition from the normal to the superfluid phase after a local heating by a neutron capture reaction is studied. The results are interpreted in terms of the Kibble-Zurek vortex creation scenario. In the third part, the influence on the superfluid states of the confinement of 3He in anisotropic aerogel is studied. Using NMR techniques, predictions of the appearance of a new phase labeled polar phase are tested, and evidence for the observation of a new precessing mode is presented. (author)

  8. Oxygen-sensitive {sup 3}He-MRI in bronchiolitis obliterans after lung transplantation

    Gast, Klaus K. [Klinikum der Johannes Gutenberg-Universitaet, Klinik und Poliklinik fuer diagnostische und interventionelle Radiologie, Mainz (Germany); Biedermann, Alexander [Klinikum der Johannes Gutenberg-Universitaet, 3. Medizinische Klinik, Pulmonologie, Mainz (Germany); Herweling, Annette [Klinikum der Johannes Gutenberg-Universitaet, Klinik fuer Anaesthesiologie, Mainz (Germany); Schreiber, Wolfgang G. [Klinikum der Johannes Gutenberg-Universitaet, Klinik und Poliklinik fuer diagnostische und interventionelle Radiologie, MR-Physik, Mainz (Germany); Schmiedeskamp, Joerg [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany); Mayer, Eckhard [Klinikum der Johannes Gutenberg-Universitaet, Klinik fuer Herz-, Thorax- und Gefaesschirurgie, Mainz (Germany); Heussel, Claus P. [Abteilung fuer Radiologie, Thoraxklinik Heidelberg, Heidelberg (Germany); Markstaller, Klaus; Eberle, Balthasar [Inselspital/Universitaetsspital, Klinik fuer Anaesthesiologie, Bern (Switzerland); Kauczor, Hans-Ulrich [Radiologie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany)

    2008-03-15

    Oxygen-sensitive {sup 3}He-MRI was studied for the detection of differences in intrapulmonary oxygen partial pressure (pO{sub 2}) between patients with normal lung transplants and those with bronchiolitis obliterans syndrome (BOS). Using software developed in-house, oxygen-sensitive {sup 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, {sup 3}He-MRI was assessed blindedly for ventilation defects. Median intrapulmonary pO{sub 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 {sup 3}He-MRI appears capable of demonstrating differences of intrapulmonary pO2 between normal lung grafts and grafts affected by BOS. Oxygen-sensitive {sup 3}He-MRI may add helpful regional information to other diagnostic techniques for the assessment and follow-up of lung transplant recipients. (orig.)

  9. Coherent deeply virtual Compton scattering off 3He and neutron generalized parton distributions

    Rinaldi, Matteo

    2014-01-01

    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 tilde-H 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 tilde-H, 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 DVC...

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

    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.

  11. Complementary aspects of the (d,3He) and (e,e'p) reactions

    Proton-hole states have been investigated by both the (d,3He) pick-up and quasi-free (e,e'p) knockout reactions. Both reactions have their advantages and disadvantages. In the (d,3He) reaction employing ploarized deutrons, both the orbital and total angular momenta, l and j, of the transferred proton can be determined, whereas the (e, e'p) reaction presently allows only the determination of the transferred l-value. The (d,3He) reaction samples only the asymptotic tail of the picked-up proton wavefunction due to strong absorption effects on the projectile and ejectile. This incomplete sampling leads to large uncertainties in the extracted spectroscopic factors. The (e,e'p) reaction, on the other hand, probes the entire proton wavefunction in momentum space, thus yielding much more reliable spectroscopic factors. It is argued that some uncertainties in the (d,3He) reaction description can be reduced if information from the (e,e'p) reaction is employed. Two-step processes are sufficiently small in the (e, e'p) reaction, although not negligible, thus enabling a more reliable study of small wavefunction components than with the (d, 3He) reaction. (author). 16 refs., 4 figs

  12. Multi-Spacecraft Observations of Recurrent 3He-Rich Solar Energetic Particles

    Bucik, R; Mall, U; Korth, A; Mason, G M; Gomez-Herrero, R

    2014-01-01

    We study the origin of 3He-rich solar energetic particles (<1 MeV/nucleon) that are observed consecutively on STEREO-B, ACE, and STEREO-A spacecraft when they are separated in heliolongitude by more than 90{\\deg}. The 3He-rich period on STEREO-B and STEREO-A commences on 2011 July 1 and 2011 July 16, respectively. The ACE 3He-rich period consists of two sub-events starting on 2011 July 7 and 2011 July 9. We associate the STEREO-B July 1 and ACE July 7 3He-rich events with the same sizeable active region producing X-ray flares accompanied by prompt electron events, when it was near the west solar limb as seen from the respective spacecraft. The ACE July 9 and STEREO-A July 16 events were dispersionless with enormous 3He enrichment, lacking solar energetic electrons and occurring in corotating interaction regions. We associate these events with a small, recently emerged active region near the border of a low-latitude coronal hole that produced numerous jet-like emissions temporally correlated with type III r...

  13. Coherent deeply virtual Compton scattering off 3He and neutron generalized parton distributions

    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.

  14. The development of 3He neutron detectors for applications in high level gamma-ray backgrounds

    To measure high-level-activity scrap and waste, it is necessary to use neutron detectors that are insensitive to the high gamma-ray background. We have developed a combination of 3He tubes and custom preamplifiers to provide the high efficiency associated with 3He detectors with good gamma-ray rejection. We have preamplifiers with short time constants in the signal processing to help separate the neutron signals from the slower risetime gamma signals. We have compared AMPTEK (A-111) preamplifiers with Precision Data Technology (PDT 110A) preamplifiers with experimental tests for gamma rejection and radiation damage. Hot cell radiation tests using a 4.5 Ci radium source were performed using 10B and 3He detectors to evaluate relative efficiency and the ability to separate neutrons and gamma rays. The AMPTEK A-111 and PDT-110A amplifiers were exposed to gamma doses between ∼0.1 R/h and 1500 R/h to observe where the gamma pileup would interfere with the neutron counting. The conclusion is that both amplifiers can operate in gamma fields up to ∼500 R/h with modest loss of neutron efficiency. This is valid for the case of only one 3He tube (30-cm active length) connected to a single amplifier. If an amplifier services multiple tubes or longer tubes, the gamma rejection will get worse. Studies are in progress to determine the lifetime of the amplifiers and 3He tubes in the high-radiation fields

  15. Spin diffusion in normal fluid 3He in 97% porous silica-aerogel

    Spin-relaxation and spin-diffusion were investigated in a liquid 3He sample in contact with solid 3He which was adsorbed on the SiO2 strands of an aerogel. NMR experiments at 950 kHz were performed at pressures and temperatures ranging from 0 to 20 bar and from 0.2 to 100 mK, respectively. The results for the diffusion coefficient D0 are not only affected by the effective mean free path in the aerogel but also by the solid-layer magnetization. For T0∼T has been observed which is caused by scattering processes associated with the spin-polarization of adsorbed solid 3He-layers

  16. Experimental study of the 56Ni(3He,d)57Cu reaction in inverse kinematics

    Measurements of (3He,d) reactions can provide information on the proton widths of states that play a role in astrophysically important (p,γ) reactions. We report on the first study of the (3He,d) reaction in inverse kinematics with a 56Ni (T1/2=6.1 d) ion beam. The Q-value resolution of ∼ keV achieved in this experiment was sufficient to separate the transitions populating the ground state and the 1/2--5/2- doublet at Ex∼1.1 MeV in 57Cu. Prospects for similar (3He,d) experiments with improved energy resolution are also discussed.

  17. Longitudinal assessment of treatment effects on pulmonary ventilation using 1H/3He MRI multivariate templates

    Tustison, Nicholas J.; Contrella, Benjamin; Altes, Talissa A.; Avants, Brian B.; de Lange, Eduard E.; Mugler, John P.

    2013-03-01

    The utitlity of pulmonary functional imaging techniques, such as hyperpolarized 3He MRI, has encouraged their inclusion in research studies for longitudinal assessment of disease progression and the study of treatment effects. We present methodology for performing voxelwise statistical analysis of ventilation maps derived from hyper­ polarized 3He MRI which incorporates multivariate template construction using simultaneous acquisition of IH and 3He images. Additional processing steps include intensity normalization, bias correction, 4-D longitudinal segmentation, and generation of expected ventilation maps prior to voxelwise regression analysis. Analysis is demonstrated on a cohort of eight individuals with diagnosed cystic fibrosis (CF) undergoing treatment imaged five times every two weeks with a prescribed treatment schedule.

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

    Brinkman, W. F.

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

  19. Tritium production, management and its impact on safety for a D3He fusion reactor

    This paper reports that about three percent of the fusion energy produced by the D-3He reactor is in the form of neutrons. Those neutrons are generated by D-D and D-T reactions, with the tritium produced by the D-D fusion. The neutrons will react with structural steel, deuterium, 3He and shielding material to produce tritium. about half of the tritium generated by the D-D reaction will not burn in the plasma and will exit as a part of the plasma exhaust. Thus, there is enough tritium produced in a D-3He reactor and careful management will be required. The tritium produced in the shield and plasma can be managed with an acceptable effect on cost and safety

  20. Study of 68Zn, 70Zn and 74Ge using the (d,3He) reaction

    The 69Ga, 71Ga(d,3He)68Zn, 70Zn and 75As(d,3He)74Ge reactions have been studied at 26MeV with an overall resolution of 18-20keV using a split pole magnetic spectrometer. Spectroscopic factors have been extracted for 16 levels in 68Zn, 14 levels in 70Zn and 24 levels in 74Ge. The ratio R=sigma(02+)/sigma(0+g.s.) shows a singularity at N=40. The small value of R for 74Ge is consistent with a previously proposed description of the structure of the states involved which is based on a simple mixing of psub(3/2) and fsub(5/2) proton configurations. The results for the Ga(d,3He)Zn reactions are compared to a recent shell model calculation

  1. Antisymmetry and channel coupling contributions to the absorption for $p + \\alpha /d + ^{3}He$

    Cooper, S G

    1997-01-01

    To understand recently established empirical p + alpha potentials, RGM calculations followed by inversion are made to study contributions of the d + 3He reaction channels and deuteron distortion effects to the p + alpha potential. An equivalent study of the d + 3He potential is also presented. The contributions of exchange non-locality to the absorption are simulated by including an phenomenological imaginary potential in the RGM. These effects alone strongly influence the shape of the imaginary potentials for both p + alpha and d + 3He. The potentials local-equivalent to the fully antisymmetrised-coupled channels calculations have a significant parity-dependence in both real and imaginary components, which for p + alpha is qualitatively similar to that found empirically. The effects on the potentials of the further inclusion of deuteron distortion are also presented. The inclusion of a spin-orbit term in the RGM, adds additional terms to the phase-equivalent potential, most notably the comparatively large im...

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

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

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

  3. Feasibility study of a sup 3 He-magnetometer for neutron electric dipole moment experiments

    Borisov, Y; Leduc, M; Lobashev, V; Otten, E W; Sobolev, Y

    2000-01-01

    We report on a sup 3 He-magnetometer capable of detecting tiny magnetic field fluctuations of less than 10 sup - sup 1 sup 4 T in experiments for measuring the electric dipole moment (EDM) of the neutron. It is based on the Ramsey technique of separated oscillating fields and uses nuclear spin-polarized sup 3 He gas which is stored in two vessels of V approx =10 l in a sandwich-type arrangement around the storage bottle for ultra-cold neutrons (UCN). The gas is polarized by means of optical pumping in a separate, small discharge cell at pressures around 0.5 mbar and is then expanded into the actual magnetometer volume. To detect the polarization of sup 3 He gas at the end of the storage cycle the gas is pumped out by means of an oil-diffusion pump and compressed again into the discharge cell where optical detection of nuclear polarization is used.

  4. The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers

    Çetin, Füsun

    2007-04-01

    Nuclear-pumped lasers (NPLs) are driven by the products of nuclear reactions and directly convert the nuclear energy to directed optical energy. Pumping gas lasers by nuclear reaction products has the advantage of depositing large energies per reaction. The need for high laser power output implies high operating pressure. In the case of volumetric excitation by 3He(n, p)3H reactions, however, operation at high pressure (more than a few atm) causes excessive neutron attenuation in the 3He gas. This fact adversely effects on energy deposition and, hence, laser output power and beam quality. Here, spatial and temporal variations of neutron flux inside a closed 3He -filled cylindrical laser tube have been numerically calculated for various tube radii and operating pressures by using a previously reported dynamic model for energy deposition. Calculations are made by using ITU TRIGA Mark II Reactor as the neutron source. The effects of neutron attenuation on power deposition are examined.

  5. Drag Force on a High Porosity Aerogel in Liquid 3He

    We discuss the drag force exerted on a high porosity aerogel in liquid 3He and its effect on sound propagation. The drag force is governed by distinct laws depending on the Knudsen number Kn, the ratio of the quasiparticle mean free path to a characteristic linear size of a body immersed in liquid. In the liquid 3He-aerogel system, the characteristic length scale is aerogel strand diameter and both of the Knudsen limit (Kn ≫ 1) and the hydrodynamic limit (Kn ≪ 1) can be achieved in the normal phase by varying temperature. We show that the crossover between the two limits can be found as a drastic change in the temperature dependence of sound attenuation in the normal phase of liquid 3He in aerogel.

  6. Motion of 3He quasiparticles in aerogel driven by fourth sound

    While the shear viscous motion of the normal fluid component causes the energy loss of the fourth sound resonance in superfluid 3He confined in narrow pores, it is not yet clear what causes the energy loss of the fourth sound in the aerogel system. We prepared two aerogel samples of 99.0% and 97.5% porosities, which were directly grown in sintered silver sponges and performed the fourth sound resonance experiments. We found that the energy loss of the fourth sound resonance in aerogel is much smaller than that in pure liquid 3He, showing that the mean free path of 3He quasiparticles is strongly suppressed by aerogel strands. Such behavior is explained with the frictional flow. The temperature dependence of the frictional relaxation time will be discussed.

  7. First doubly polarised photoproduction on {sup 3}He at the photon beam of MAMI

    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.)

  8. Boron-coated straws as a replacement for {sup 3}He-based neutron detectors

    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.

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

    Saunders, John

    2008-03-01

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

  10. Boron-coated straws as a replacement for 3He-based neutron detectors

    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.