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Sample records for 2h 3he 6li

  1. Effects on distortion on the inter cluster motion in 2H, 3He, 6Li and 9Be on Trojan Horse applications

    Deuteron induced quasi-free scattering and reactions have been extensively investigated in the past few decades as well as 6Li, 3H, 3He and 9Be induced ones. This was done not only for nuclear structure and reaction mechanisms investigation but also for important astrophysical implications (Trojan Horse Method)[1]. In particular the width and the shape of the spectator momentum distribution inside several nuclei which have been used as Trojan Horse ones have been obtained as a function of the transferred momentum for all these nuclei. The behaviour of the width of the spectator momentum distribution as a function of the transferred momentum will be discussed extensively. This work is the continuation of what has been done for Li6 in [2]. Moreover a complete study on Trojan Horse method applications will also be given because the momentum distribution of the spectator particle inside the Trojan horse nucleus is a necessary input for the application of this method. This will give hints on distortion effects at low energies as well as implications for nuclear astrophysics.(author)

  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. sup 3 He( sub 3 H,. gamma. ) sup 6 Li; Source of sup 6 Li production in the big bang

    Funck, C.; Langanke, K. (Inst. fur Theoretisch Physik I, Univ. Munster, D-4400 Munster (DE))

    1990-01-10

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

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

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

  5. An Updated 6Li(p, α)3He Reaction Rate at Astrophysical Energies with the Trojan Horse Method

    Lamia, L.; Spitaleri, C.; Pizzone, R. G.; Tognelli, E.; Tumino, A.; Degl'Innocenti, S.; Prada Moroni, P. G.; La Cognata, M.; Pappalardo, L.; Sergi, M. L.

    2013-05-01

    The lithium problem influencing primordial and stellar nucleosynthesis is one of the most interesting unsolved issues in astrophysics. 6Li is the most fragile of lithium's stable isotopes and is largely destroyed in most stars during the pre-main-sequence (PMS) phase. For these stars, the convective envelope easily reaches, at least at its bottom, the relatively low 6Li ignition temperature. Thus, gaining an understanding of 6Li depletion also gives hints about the extent of convective regions. For this reason, charged-particle-induced reactions in lithium have been the subject of several studies. Low-energy extrapolations of these studies provide information about both the zero-energy astrophysical S(E) factor and the electron screening potential, Ue . Thanks to recent direct measurements, new estimates of the 6Li(p, α)3He bare-nucleus S(E) factor and the corresponding Ue value have been obtained by applying the Trojan Horse method to the 2H(6Li, α 3He)n reaction in quasi-free kinematics. The calculated reaction rate covers the temperature window 0.01 to 2T 9 and its impact on the surface lithium depletion in PMS models with different masses and metallicities has been evaluated in detail by adopting an updated version of the FRANEC evolutionary code.

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

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

  7. Comparison of Thermal Neutron Detection Efficiency of $^{6}$Li Scintillation Glass and $^{3}$He Gas Proportional Tube

    Xu, Ming; Tang, Zhi-Cheng; Chen, Guo-Ming; Tao, Jun-Quan

    2013-01-01

    We report on a comparison study of the $^{3}$He gas proportional tube and the $^{6}$Li incorporated scintillation glasses on thermal neutron detection efficiency. Both $^{3}$He and $^{6}$Li are used commonly for thermal neutron detection because of their high neutron capture absorption coefficient. By using a neutron source $^{252}$Cf and a paraffin moderator in an alignment system, we can get a small beam of thermal neutrons. A flash ADC is used to measure the thermal neutron spectrum of eac...

  8. 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

  9. AN UPDATED {sup 6}Li(p, {alpha}){sup 3}He REACTION RATE AT ASTROPHYSICAL ENERGIES WITH THE TROJAN HORSE METHOD

    Lamia, L.; Spitaleri, C.; Sergi, M. L. [Dipartimento di Fisica e Astronomia, Universita di Catania, I-95123 Catania (Italy); Pizzone, R. G.; Tumino, A.; La Cognata, M. [INFN-Laboratori Nazionali del Sud, I-95125 Catania (Italy); Tognelli, E.; Degl' Innocenti, S.; Prada Moroni, P. G. [Dipartimento di Fisica, Universita di Pisa, I-56127 Pisa (Italy); Pappalardo, L. [Dipartimento di Fisica e Scienze della Terra, Universita di Ferrara, I-44100 Ferrara (Italy)

    2013-05-01

    The lithium problem influencing primordial and stellar nucleosynthesis is one of the most interesting unsolved issues in astrophysics. {sup 6}Li is the most fragile of lithium's stable isotopes and is largely destroyed in most stars during the pre-main-sequence (PMS) phase. For these stars, the convective envelope easily reaches, at least at its bottom, the relatively low {sup 6}Li ignition temperature. Thus, gaining an understanding of {sup 6}Li depletion also gives hints about the extent of convective regions. For this reason, charged-particle-induced reactions in lithium have been the subject of several studies. Low-energy extrapolations of these studies provide information about both the zero-energy astrophysical S(E) factor and the electron screening potential, U{sub e} . Thanks to recent direct measurements, new estimates of the {sup 6}Li(p, {alpha}){sup 3}He bare-nucleus S(E) factor and the corresponding U{sub e} value have been obtained by applying the Trojan Horse method to the {sup 2}H({sup 6}Li, {alpha} {sup 3}He)n reaction in quasi-free kinematics. The calculated reaction rate covers the temperature window 0.01 to 2T{sub 9} and its impact on the surface lithium depletion in PMS models with different masses and metallicities has been evaluated in detail by adopting an updated version of the FRANEC evolutionary code.

  10. Comparison of thermal neutron detection efficiency of 6Li scintillation glass and 3He gas proportional tube

    We report on a comparison study of the 3He gas proportional tube and the 6Li incorporated scintillation glasses on thermal neutron detection efficiency. Both 3He and 6Li are used commonly for thermal neutron detection because of their high neutron capture absorption coefficient. By using a neutron source 252Cf and a paraffin moderator in an alignment system, we can get a small beam of thermal neutrons. A flash ADC is used to measure the thermal neutron spectrum of each detector, and the detected number of events is determined from the spectrum, then we can calculate the detection efficiency of different detectors. Meanwhile, the experiment has been modeled with GEANT4 to validate the results against the Monte Carlo simulation. (authors)

  11. Study of the reactions 6Li(pα)3He, 6Li(dα)4He, 6Li(dp0)7Li and 6Li(dp1)7Li* from 300 keV to 1000 keV

    Experimental results are presented for the four reactions 6Li (pα)3He, 6Li (dα)4He, 6Li (dp0)7Li and 6Li (dp1)7Li* between 300 keV and 1000 keV. The angular distributions, the excitation curves and the total cross-section curves are presented in absolute values. (authors)

  12. The Trojan-Horse Method applied to the {sup 6}Li(p,{alpha}){sup 3}He reaction down to astrophysical energies

    Tumino, A.; Spitaleri, C.; Pappalardo, L.; Cherubini, S.; Del Zoppo, A.; La Cognata, M.; Musumarra, A.; Pellegriti, M.G.; Pizzone, R.G.; Rinollo, A.; Romano, S.; Typel, S

    2004-04-05

    The Trojan-Horse Method has been applied to the three-body d({sup 6}Li,{alpha}{sup 3}He)n break-up reaction in order to extract the bare nucleus S(E) factor for the {sup 6}Li(p,{alpha}){sup 3}He down to astrophysical energies.

  13. THE 2H(alpha, gamma6LI REACTION AT LUNA AND BIG BANG NUCLEOSYNTHETIS

    Carlo Gustavino

    2013-12-01

    Full Text Available The 2H(α, γ6Li reaction is the leading process for the production of 6Li in standard Big Bang Nucleosynthesis. Recent observations of lithium abundance in metal-poor halo stars suggest that there might be a 6Li plateau, similar to the well-known Spite plateau of 7Li. This calls for a re-investigation of the standard production channel for 6Li. As the 2H(α, γ6Li cross section drops steeply at low energy, it has never before been studied directly at Big Bang energies. For the first time the reaction has been studied directly at Big Bang energies at the LUNA accelerator. The preliminary data and their implications for Big Bang nucleosynthesis and the purported 6Li problem will be shown.

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

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

    2015-07-15

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

  15. Second-class currents and the muon neutrino rest mass in the muon capture processes by 6Li and 3He nuclei

    The influence of second class currents (SCC) and that of the muon neutrino rest mass (mνμ) on the differential muon capture rate by the 6Li and 3He, and on the angular asymmetry coefficient (aμν) of the neutrino emission direction with respect to the muon spin orientation, is investigated. It is shown that the experimental study of aμν may give an efficient estimation for mνμ and for SCC form factors FT (in the case of 6Li and 3He) and FS (in the case of 3He). 26 refs

  16. Alpha-spectroscopic factors from (d,6Li) and (3He,7Be) reactions on 12C,24Mg,40Ca and 58Ni

    An attempt has been made to compare the alpha-spectroscopic factors (Ssub(α)) resulting from (d,6Li) and (3He,7Be) reactions on 12C,24Mg,40Ca and 58Ni employing potentials characterizing the same potential family for the deuteron and for the 3He-channels and another set of potentials characterizing a particular potential family for 6Li and 7Be-channels respectively. It is found that the extracted spectroscopic factors for 12C,24Mg and 40Ca agree well, while that for the target 58Ni differs by an order of magnitude from the other two reactions. A possible reason has been discussed. (author)

  17. First direct measurement of the 2H(α,γ)6Li cross section at Big Bang energies at LUNA

    The amount of 6Li produced during the Big Bang Nucleosynthesis (BBN) era can be theoretically estimated on the basis of cosmological and nuclear astrophysics knowledge. The latter strongly depends on the measurement of the nuclear cross section of the processes involved in the production and destruction of 6Li during the first stages of the Universe. Whereas the destruction process cross sections are well known, the reaction that dominates the 6Li production, the 2H(α,γ)6Li, has never been directly measured in the BBN energy range and only upper limits coming from indirect measurements are available till now. Here we report the first direct measurement of the 2H(α,γ)6Li cross section at BBN energies obtained at LUNA (Laboratory for Underground Nuclear Astrophysics, LNGS, Italy). (author)

  18. A Search for ^2H, ^3H, and ^3He in Large Solar Flares

    Mewaldt, R. A.; Stone, E. C.

    1983-01-01

    The results of a new study of solar flare H and He isotopes imply that earlier observations have significantly overestimated the abundances of ^2H, ^3H, and ^3He in large solar flares. We find no evidence that solar flare nuclei have suffered any significant amount of fragmentation before escaping from the Sun.

  19. A microscopic three-cluster model with nuclear polarization applied to the resonances of 7Be and the reaction 6Li(p,3He)4He

    Vasilevsky, V S; Broeckhove, J; Kovalenko, T P

    2008-01-01

    A microscopic model for three-cluster configurations in light nuclei is presented. It uses an expansion in terms of Faddeev components for which the dynamic eqations are derived. The model is designed to investigate binary channel processes in a compound system. Gaussian and oscillator bases are used to expand the wave function and to represent appropriate boundary conditions. We study the effect of cluster polarization on ground and resonance states of 7Be, and on the astrophysical S-factor of the reaction 6Li(p,3He)4He.

  20. Big Bang nucleosynthesis and the results of the 2H(α,γ)6Li experiment at LUNA

    Observations of the 6Li abundance in very metal-poor stars, if confirmed, show a level of 6Li that is several orders of magnitude larger than the production of this nuclide in standard Big Bang nucleosynthesis. The 2H(α,γ)6Li nuclear reaction is believed to dominate 6Li production in the Big Bang, but there are no directly measured data at relevant energies yet. The reaction has been studied at the LUNA 0.4 MV accelerator, deep underground in the Gran Sasso laboratory in Italy, using an intensive He+ beam and a windowless deuterium gas target. The conclusions from the final data analysis of the experiment are presented.

  1. Total photoabsorption cross sections for 1H, 2H and 3He from 200 to 800 MeV

    The total photoabsorption cross sections for 1H, 2H and 3He have been measured for incident photon energies ranging from 200 to 800 MeV. The results show clearly the changes in the nucleon resonances in going from 1H to 3He. In particular, for the D13 region the behaviour for 3He is intermediate between that for 1H, 2H and heavier nuclei. (author)

  2. Nonfactorized Calculation of the Process 3He(e,e'p)2H at Medium Energies

    The exclusive process 3He(e,e'p)2H has been analyzed by a nonfactorized and parameter-free approach based upon realistic few-body wave functions corresponding to the AV18 interaction and treating the rescattering of the struck nucleon within a generalized eikonal approximation. The results of our calculations, compared with recent JLab experimental data, show that the left-right asymmetry exhibits a clear dependence upon the final state interaction demonstrating the breaking down of the factorization approximation at 'negative' and large (> or approx. 300 MeV/c) values of the missing momentum

  3. The Astrophysical S-factor for the 2H(, )6Li Nuclear Reaction at Low-Energies

    H. Sadeghi; A. Moghadasi; M. Ghamary

    2014-12-01

    The alpha radiative capture reactions are the key to understand about primordial nucleosynthesis and the observed abundance of light nucleus in stars. The astrophysical S-factor for the process 2H(, )6Li has been calculated at the low-energies relevant to big-bang nucleosynthesis and in comparison with laboratory data. On the basis of the model, the alpha radiative capture process is studied by using the two-and three-body electromagnetic currents. The bound and resonance states of 6Li are calculated via an inverse process, deuteron- photodisintegration of a 6Li nucleus. In comparison with other theoretical approaches and available laboratory data, excellent agreement is achieved for the astrophysical S-factor of this process.

  4. 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.)

  5. 2H(p,γ)3He reaction using polarized and unpolarized protons

    The 900 yield curve for the 2H(p,γ) 3He reaction has been studied over the excitation region in 3He of approximately 7 to 15 MeV. Both polarized and unpolarized proton beams were used to measure the angular distributions of cross section and analyzing power at E/sub x/ = 8.83, 9.83, and 10.83 MeV. If only the four non-spin-flip E1 and E2 T-matrix elements are considered, their amplitudes and relative phases can be extracted. The E2 cross section obtained from this analysis is found to be (12 +- 5) % of the total cross section. The detailed balanced differential (theta/sub lab/ = 900) and total cross sections at E/sub x/ = 10.83 MeV are found to be (117 +- 11) μb/sr and (1.07 +- 0.11) mb, respectively; the quoted errors represent the total uncertainties in the cross sections obtained in this experiment. The results are also compared with recent E1 and E2 calculations

  6. Neutron-induced background by an {alpha}-beam incident on a deuterium gas target and its implications for the study of the {sup 2}H({alpha},{gamma}){sup 6}Li reaction at LUNA

    Anders, M.; Bemmerer, D.; Elekes, Z.; Marta, M. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Trezzi, D.; Mazzocchi, C. [INFN, Sezione di Milano, Milano (Italy); Bellini, A.; Costantini, H.; Corvisiero, P.; Lemut, A.; Prati, P. [Universita di Genova (Italy); INFN, Sezione di Genova, Dipartimento di Fisica, Genova (Italy); Aliotta, M.; Davinson, T.; Scott, D. [University of Edinburgh, SUPA, School of Physics and Astronomy, Edinburgh (United Kingdom); Broggini, C.; Caciolli, A.; Erhard, M.; Menegazzo, R.; Rossi Alvarez, C. [INFN, Sezione di Padova, Padova (Italy); Formicola, A.; Junker, M. [Laboratori Nazionali del Gran Sasso, INFN, Assergi (Italy); Fueloep, Zs.; Gyuerky, G.; Somorjai, E.; Szuecs, T. [Institute of Nuclear Research (ATOMKI), Debrecen (Hungary); Gervino, G. [Universita di Torino (Italy); INFN, Dipartimento di Fisica Sperimentale, Torino (Italy); Guglielmetti, A. [INFN, Sezione di Milano, Milano (Italy); Universita degli Studi di Milano, Milano (Italy); Gustavino, C. [INFN, Sezione di Roma ' ' La Sapienza' ' , Roma (Italy); Straniero, O. [INFN, Sezione di Napoli, Napoli (Italy); Osservatorio Astronomico di Collurania, Teramo (Italy); Collaboration: LUNA Collaboration

    2013-02-15

    The production of the stable isotope {sup 6}Li in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological {sup 6}Li plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of {sup 7}Li abundances and would point to a predominantly primordial origin of {sup 6}Li, contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang {sup 6}Li production must be revisited. The main production channel for {sup 6}Li in the Big Bang is the {sup 2}H({alpha},{gamma}){sup 6}Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an {alpha}-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the {sup 2}H(d,n){sup 3}He reaction. Due to the ultra-low laboratory neutron background at LUNA, the effect of this weak flux of 2-3 MeV neutrons on well-shielded high-purity germanium detectors has been studied in detail. Data have been taken at 280 and 400keV {alpha}-beam energy and for comparison also using an americium-beryllium neutron source. (orig.)

  7. New determination of the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reaction rates at astrophysical energies

    Tumino, A.; Spartà, R.; Spitaleri, C.; Pizzone, R. G.; La Cognata, M.; Rapisarda, G. G.; Romano, S.; Sergi, M. L. [Laboratori Nazionali del Sud-INFN, Catania (Italy); Mukhamedzhanov, A. M. [Cyclotron Institute Texas A and M University-College Station, Texas (United States); Typel, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH-Theorie Darmstadt (Germany); Tognelli, E.; Degl' Innocenti, S.; Prada Moroni, P. G. [Dipartimento di Fisica, Università di Pisa, and INFN-Sezione di Pisa, Pisa (Italy); Burjan, V.; Kroha, V.; Hons, Z.; Mrazek, J.; Piskor, S. [Nuclear Physics Institute of ASCR-Rez near Prague (Czech Republic); Lamia, L., E-mail: tumino@lns.infn.it [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania (Italy)

    2014-04-20

    The cross sections of the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions have been measured via the Trojan Horse method applied to the quasi-free {sup 2}H({sup 3}He,p {sup 3}H){sup 1}H and {sup 2}H({sup 3}He,n {sup 3}He){sup 1}H processes at 18 MeV off the proton in {sup 3}He. For the first time, the bare nucleus S(E) factors have been determined from 1.5 MeV, across the relevant region for standard Big Bang nucleosynthesis, down to the thermal energies of deuterium burning in the pre-main-sequence (PMS) phase of stellar evolution, as well as of future fusion reactors. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from the available direct data and existing fitting curves, with substantial variations in the electron screening by more than 50%. As a consequence, the reaction rates for astrophysics experience relevant changes, with a maximum increase of up to 20% at the temperatures of the PMS phase. From a recent primordial abundance sensitivity study, it turns out that the {sup 2}H(d,n){sup 3}He reaction is quite influential on {sup 7}Li, and the present change in the reaction rate leads to a decrease in its abundance by up to 10%. The present reaction rates have also been included in an updated version of the FRANEC evolutionary code to analyze their influence on the central deuterium abundance in PMS stars with different masses. The largest variation of about 10%-15% pertains to young stars (≤1 Myr) with masses ≥1 M {sub ☉}.

  8. First direct measurement of the 2H(α,γ)6Li cross section at big bang energies and the primordial lithium problem.

    Anders, M; Trezzi, D; Menegazzo, R; Aliotta, M; Bellini, A; Bemmerer, D; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Davinson, T; Elekes, Z; Erhard, M; Formicola, A; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Prati, P; Rossi Alvarez, C; Scott, D A; Somorjai, E; Straniero, O; Szücs, T

    2014-07-25

    Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The much higher (6)Li/(7)Li values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature. PMID:25105610

  9. {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions at sub-coulomb energies

    Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Sparta, R.; Aliotta, M.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Mrazek, J.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L. [Universita degli Studi di Enna Kore, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); Cyclotron Institute Texas A and M University - College Station, Texas (United States); Excellence Cluster Universe - Technische Universitaet Muenchen, Garching, Germany and GSI Helmholtzzentrum fuer Schwerionenforschung GmbH - Theorie Darmstadt (Germany); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); School of Physics and Astronomy - University of Edinburgh, SUPA (United Kingdom); Nuclear Physics Institute of ASCR - Rez near Prague (Czech Republic); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy); Nuclear Physics Institute of ASCR - Rez near Prague (Czech Republic); Dipartimento di Fisica e Astronomia, Universita di Catania, and Laboratori Nazionali del Sud - INFN, via S. Sofia 62, 95123 Catania (Italy)

    2012-11-20

    The {sup 2}H({sup 3}He,p{sup 3}H){sup 1}H and {sup 2}H({sup 3}He,n{sup 3}He){sup 1}H processes have been measured in quasi free kinematics to investigate for the first time the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions by means of the Trojan Horse Method. The {sup 3}He+d experiment was performed at 18 MeV, corresponding the a d-d energy range from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre Main Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the bare nucleus S(E) factors have been extracted for the first time. They deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

  10. Impact of alternate fusion fuels on fusion reactor technology: an initial assessment study. [Catalyzed D, D-/sup 3/He, p-/sup 6/Li, p-/sup 7/Li, D-/sup 6/Li, p-/sup 11/B, /sup 3/He-/sup 3/He

    Baker, C.C.; Bolon, A.; Clemmer, R.

    1979-11-01

    The initial results of a study carried out to assess some of the technology implications of non-D-T fusion fuel cycles are presented. The primary emphasis in this report is on D-D, catalyzed-D and D-/sup 3/He fuel cycles. Tokamaks and field-reversed mirrors have been selected as sample confinement concepts. A new technique of employing neutronic computer codes to study the transport of cyclotron radiation for cases of non-uniform density and temperature profiles is described. The technology areas considered include first wall design considerations, shielding requirements, fuel cycle requirements and some safety and environmental considerations. Conclusions resulting from the study are also presented.

  11. Quasi-free photoproduction of η-mesons off 2H and 3He

    In this work, we are presenting a combination of two preliminary results for quasi-free photoproduction of η-mesons from the liquid deuterium and 3He targets for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI electron accelerator, using the Glasgow tagged photon facility. Decay photons of the η-mesons and the recoil nucleons were detected with an almost 4π covering electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets show a narrow structure in the excitation function of γ + n → n + η. The results from the two measurements are consistent within the expected effects from nuclear Fermi motion. (author)

  12. S-factor measurement of the 2H(α,γ)6Li reaction at energies relevant for Big-Bang nucleosynthesis

    For about 20 years now, observations of 6Li in several old metal-poor stars inside the halo of our galaxy have been reported, which are largely independent of the stars' metallicity, and which point to a possible primordial origin. The observations exceed the predictions of the Standard Big-Bang Nucleosynthesis model by a factor of 500. In the relevant energy range, no directly measured S-factors were available yet for the main production reaction 2H(α,γ)6Li, while different theoretical estimations have an uncertainty of up to two orders of magnitude. The very small cross section in the picobarn range has been measured with a deuterium gas target at the LUNA accelerator (Laboratory for Underground Nuclear Astrophysics), located deep underground inside Laboratori Nazionali del Gran Sasso in Italy. A beam-induced, neutron-caused background in the γ-detector occurred which had to be analyzed carefully and subtracted in an appropriate way, to finally infer the weak signal of the reaction. For this purpose, a method to parameterize the Compton background has been developed. The results are a contribution to the discussion about the accuracy of the recent 6Li observations, and to the question if it is necessary to include new physics into the Standard Big-Bang Nucleosynthesis model.

  13. Neutron-induced background by an alpha-beam incident on a deuterium gas target and its implications for the study of the 2H(alpha,gamma)6Li reaction at LUNA

    Anders, M; Bellini, A; Aliotta, M; Bemmerer, D; Broggini, C; Caciolli, A; Costantini, H; Corvisiero, P; Davinson, T; Elekes, Z; Erhard, M; Formicola, A; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Menegazzo, R; Prati, P; Alvarez, C Rossi; Scott, D; Somorjai, E; Straniero, O; Szücs, T

    2013-01-01

    The production of the stable isotope Li-6 in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological Li-6 plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of Li-7 abundances and would point to a predominantly primordial origin of Li-6, contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang Li-6 production must be revisited. The main production channel for Li-6 in the Big Bang is the 2H(alpha,gamma)6Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an {\\alpha}-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the 2H(d,n)3He reaction....

  14. A study of the inclusive inelastic scattering of 100 MeV pions from 2H, 3He and 4He

    Measurements were carried out of the double-differential cross sections of 100 MeV positive and negative pions inelastically scattered from 2H, 3He and 4He. Inclusive spectra and angular distributions of the scattered pions from the (π,π') reaction were obtained at several angles for the three targets using a magnetic spectrometer. The targets considered in the experiment were all gases. The yields of the scattered pions from 2H, 3He and 4He were normalized to measured 1H scattering data and to the known π+N cross sections in the literature. The angular distributions of 100 MeV pions scattered from 2H, 3He and 4He at the back angles (θ/sub lab/ ≥ 750) were found to have very nearly the same shape as the free π+-p distribution at this energy. The ratios of the energy- and angle-integrated π+ inelastic scattering cross sections at the back angles compared to the free π+-p cross sections were found to be 0.69 +- 0.03 for 2H, 1.42 +- 0.06 for 3He, and 0.88 +- 0.03 for 4He. The inelastic scattering reaction of pions from 2H, 3He and 4He were interpreted from the point of view that the initial interaction is that of a pion with a single nucleon. Classical and quantum mechanical calculations were carried out to better understand the πN interaction inside nuclei. It was found that pion interactions with 2H, 3He and 4He at energies below the (3,3) resonance can be viewed effectively in terms of pion interaction with individual nucleons in these nuclei. It was also found that pion absorption cross section in 4He is unusually large compared to that in other nuclei. Some possible reasons are suggested for this behavior of pions interacting with 4He. 80 refs., 42 figs., 29 tabs

  15. Total cross sections of the charge exchange reaction (π+,π0) on 2H, 3He, and 4He across the Δ(1232) resonance

    Results from a 4π solid angle measurement of the inclusive reaction (π+,π0) on 2H, 3He, and 4He at incident pion energies of Tπ+=70, 118, 162, 239, and 330 MeV are presented. The single charge exchange total cross sections were determined, and are compared to previous results and simple models of π endash few-nucleon interactions. On the helium isotopes a strong damping of the cross sections in the Δ(1232) energy region is observed. Total cross sections of the breakup reaction π++2H →π+pn are also given. copyright 1999 The American Physical Society

  16. 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.

  17. Measurement of transverse response functions, longitudinal response functions and transverse-longitudinal response functions in the reaction 3He(e,e'p)2H for q transferred moments ≤1.GeV/c

    The cross-sections of the 3He(e,e'p)2H reaction have been measured for q transfer moments between 250 and 880 MeV/c and PR recoil momentum between 0 and 210 MeV/c. We have deduced the values of the transverse (magnetic) response functions (T), of the longitudinal (Coulomb) response functions (L) and transverse-longitudinal response functions (TL). The study of the T response functions has shown that the electron-proton operator inside the 3He nucleus behaves like a free operator for q values above 500 MeV/c. The ratio L/T is close to 1, and the absolute values of the 2 response functions agree well with theoretical prediction of the plane wave (PWIA). For q values below 400 MeV/c, some deviations from PWIA predictions appear for L and T response functions with L/T3He can be easily interpreted within the frame of the PWIA for q transfers ranging from 500 to 900 MeV/c.

  18. Updated evidences of the Trojan Horse particle invariance for $^2$H(d,p)$^3$H reaction

    Pizzone, R. G.; Spitaleri, C.(Dip. di Fisica e Astronomia, Univ. di Catania, via S. Sofia, Catania, Italy); Bertulani, C. A.; Mukhamedzhanov, A. M.; Blokhintsev, L.; M. La Cognata; Lamia, L; Rinollo, A.; Spartá, R.; A. Tumino

    2012-01-01

    The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was tested using the quasi free $^2$H($^6$Li, pt)$^4$He and $^2$H($^3$He,pt)H reactions after $^6$Li and $^3$He break-up, respectively. The astrophysical S(E)-factor for the d(d,p)t binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good ag...

  19. Measurements and calculations of neutron leakage spectra from slabs irradiated with 9Be(d, n)10B 2H(d, n)3He and Pu-Be neutrons

    The spectra of neutrons from the 9Be(d, n)10B, 2H(d, n)3He and Pu-Be sources passing through slabs of water, graphite, Al, Fe and Pb up to 20 cm in thickness were measured by a pulse height response spectrometer in the 1.5-15 MeV range. The measured leakage spectra have been compared with calculated results obtained using the three dimensional Monte-Carlo code MCNP-4A and point-wise cross sections from the ENDF/B-IV, ENDF/B-VI and JENDL-3.1 data files. A comparison of the measured and calculated data has shown that the MCNP-4A code with an appropriate library can reasonably approximate the measured leakage spectra

  20. Measurements and calculations of neutron leakage spectra from slabs irradiated with {sup 9}Be(d, n){sup 10}B {sup 2}H(d, n){sup 3}He and Pu-Be neutrons

    Olah, L.; Jordanova, J.; El-Megrab, A.M.; Darsono, Perez N.; Yousif, M.Y.A.; Csikai, J. [Institute of Experimental Physics, Kossuth University, Debrecen (Hungary); Fenyvesi, A.; Majdeddin, A.D. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary)

    1999-03-01

    The spectra of neutrons from the {sup 9}Be(d, n){sup 10}B, {sup 2}H(d, n){sup 3}He and Pu-Be sources passing through slabs of water, graphite, Al, Fe and Pb up to 20 cm in thickness were measured by a pulse height response spectrometer in the 1.5-15 MeV range. The measured leakage spectra have been compared with calculated results obtained using the three dimensional Monte-Carlo code MCNP-4A and point-wise cross sections from the ENDF/B-IV, ENDF/B-VI and JENDL-3.1 data files. A comparison of the measured and calculated data has shown that the MCNP-4A code with an appropriate library can reasonably approximate the measured leakage spectra.

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

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

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

    Olimov, K., E-mail: olimov@uzsci.net [Uzbek Academy of Sciences, Physical-Technical Institute, Fizika-Solntse Research and Production Association (Uzbekistan); Glagolev, V. V. [Joint Institute for Nuclear Research (Russian Federation); Gulamov, K. G.; Lutpullaev, S. L.; Kurbanov, A. R.; Olimov, A. K.; Petrov, V. I.; Yuldashev, A. A. [Uzbek Academy of Sciences, Physical-Technical Institute, Fizika-Solntse Research and Production Association (Uzbekistan)

    2013-07-15

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

  3. 6Li foil thermal neutron detector

    Ianakiev, Kiril D [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Chung, Kiwhan [Los Alamos National Laboratory; Macarthur, Duncan W [Los Alamos National Laboratory

    2010-01-01

    In this paper we report on the design of a multilayer thermal neutron detector based on {sup 6}Li reactive foil and thin film plastic scintillators. The {sup 6}Li foils have about twice the intrinsic efficiency of {sup 10}B films and about four times higher light output due to a unique combination of high energy of reaction particles, low self absorption, and low ionization density of tritons. The design configuration provides for double sided readout of the lithium foil resulting in a doubling of the efficiency relative to a classical reactive film detector and generating a pulse height distribution with a valley between neutron and gamma signals similar to {sup 3}He tubes. The tens of microns thickness of plastic scintillator limits the energy deposited by gamma rays, which provides the necessary neutron/gamma discrimination. We used MCNPX to model a multilayer Li foil detector design and compared it with the standard HLNCC-II (18 {sup 3}He tubes operated at 4 atm). The preliminary results of the {sup 6}Li configuration show higher efficiency and one third of the die-away time. These properties, combined with the very short dead time of the plastic scintillator, offer the potential of a very high performance detector.

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

    Ford, William P. [Old Dominion University, Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Schiavilla, Rocco [Old Dominion University, Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Van Orden, J. W. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2014-03-01

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

  5. Pion electroproduction from 6Li

    The pion electroproduction cross section from 6Li is calculated assuming the 6He nucleus is detected. The wave functions used in this calculation are those which gave the best agreement with the 6Li(γ, π+)6He data. The electroproduction experiment will provide a useful check of these wave functions. (Auth.)

  6. Contribution to the study of 6Li + 6Li et 6Li + 9Be reactions

    This research thesis reports measurements of coincidence between γ rays and particles charged in 6Li + 6Li and 6Li + 9Be reactions. These measurements have been repeated with some technical improvements which are described: discrimination between protons and alphas of 7Li* + 4He + p, simultaneous recording of fortuitous coincidences, assessment of the proportion of charged particles at a final state beyond the detection threshold. 'alpha-alpha' coincidences of the 6Li + 6Li → 3α reaction have also been recorded in conditions which better suited the rough study of the middle of the Dalitz diagram than the precise study of the burst into two energetic alphas. Some information have been obtained from 'alpha-p' coincidences of 7Li* + 4He + p and 7Li* + 4He + p. For these measurements, a multi-parametric installation has been developed for the recording of angular correlations at several simultaneous angles

  7. Deformation Effects in 6Li

    The asymptotic D - to S -state ratio η for the 6Li> bound-state overlap is determined from measurements of the tensor analyzing powers for (6Li,d ) reactions on medium-heavy targets. The reactions are described by the distorted-wave Born approximation assuming a direct α -particle transfer reaction mechanism. The calculations provide good agreement with cross section and vector analyzing power data. A best fit to the tensor analyzing power data results in a new value of η=+0.0003±0.0009 , much smaller than previous experimental and theoretical determinations. copyright 1998 The American Physical Society

  8. 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

  9. ^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.

  10. Updated evidence of the Trojan horse particle invariance for the 2H(d,p)3H reaction

    Pizzone, R. G.; Spitaleri, C.; Bertulani, C. A.; Mukhamedzhanov, A. M.; Blokhintsev, L.; La Cognata, M.; Lamia, L.; Rinollo, A.; Spartá, R.; Tumino, A.

    2013-02-01

    The Trojan horse nucleus invariance for the binary d(d,p)t reaction was tested by means of an experiment using the quasifree 2H(6Li,pt)4He and 2H(3He,pt)H reactions after 6Li and 3He breakup, respectively. The astrophysical S(E) factor for the d(d,p)t binary process was extracted from the present data in the framework of the plane wave approximation applied to the two different breakup schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the plane wave approximation and suggests the independence of the binary indirect cross section on the chosen Trojan horse nucleus also for the present case.

  11. Updated evidences of the Trojan Horse particle invariance for $^2$H(d,p)$^3$H reaction

    Pizzone, R G; Bertulani, C A; Mukhamedzhanov, A M; Blokhintsev, L; La Cognata, M; Lamia, L; Rinollo, A; Spartá, R; Tumino, A

    2012-01-01

    The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was tested using the quasi free $^2$H($^6$Li, pt)$^4$He and $^2$H($^3$He,pt)H reactions after $^6$Li and $^3$He break-up, respectively. The astrophysical S(E)-factor for the d(d,p)t binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the Plane Wave Approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case.

  12. 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

  13. 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

  14. Trojan Horse particle invariance for 2H(d,p)3H reaction: a detailed study

    Pizzone R.G.; Spitaleri C.; Bertulani C.A.; Mukhamedzhanov A.M.; Blokhintsev L.; La Cognata M.; Lamia L.; Rinollo A.; Spartá R.; Tumino A.

    2014-01-01

    In the last decades the Trojan Horse method has played a crucial role for the measurement of several charged particle induced reactions cross sections of astrophysical interest. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was therefore tested using the quasi free 2H(6Li, pt)4He and 2H(3He,pt)H reaction...

  15. 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.

  16. Multibody final states of the 6Li+6Li reaction at 97 MeV

    Absolute coincidence cross sections were measured for the reactions 6Li+6Li->3α, 6Li(6Li, 2α), and 6Li(6Li, 2d), where the latter two represent N-body (N >= 4) final states. Broad peaks from the 6Li(6Li, 2α) reaction are well described by a double spectator pole (DSP) model utilizing a Hulthen wave function, whereas near 40 MeV the DSP peaks are much narrower than predicted. A broad peak in the 3α final-state spectrum attributed to a single-spectator pole (SSP) process, is well described with the same wave function. The SSP is the principal mechanism for the 3α reaction, in contrast to data near 40 MeV which show that sequential decay from 8Be levels is dominant. (orig.)

  17. 2H(d,n)3He核反应中子注量的伴随粒子法测量%An associated particle method to measure the neutron flux from the 2H(d,n)3He reaction

    2002-01-01

    2H(d,n)3He核反应单能中子源广泛应用于几MeV中子的散射和极化实验.采用伴随粒子法测量中子注量,用Si半导体探测器测量3He粒子,用0.8μm Al箔来屏蔽散射的d束,系统可很好地分辨3He、d、T和 p,可测d+束能量到165keV,测量结果与用NE213探测器的结果相比较,一致性好于97%.

  18. Mechanisms of emission of particles charged in 6Li + 6Li and 6Li + 10B reactions at low energies

    The lithium 6 nucleus is a projectile of interest to study nuclear reactions at low energy due to the possibility to obtain high heats of reaction, and to its structure which can play an important role in the projectile-target interaction. This research thesis focused on the study of two low-energy reactions provoked by lithium projectiles. These reactions are studied within the framework of the theoretical model of aggregates. The first part presents the experimental conditions of both reactions, reports the development and analysis of nuclear plates, and the transformation of a given type of particle histogram into a spectrum in the mass centre system. The next parts report the study of the 6Li + 6Li reaction (previous results, kinematic analysis, spectrum of secondary particles, theoretical analysis of results) and of the 6Li + 10B reaction (previous results, experimental results, study of the continuous spectrum of alpha particle, reaction mechanisms)

  19. 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...

  20. 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.

  1. Using Inertial Fusion Implosions to Measure the T+^{3}He Fusion Cross Section at Nucleosynthesis-Relevant Energies.

    Zylstra, A B; Herrmann, H W; Johnson, M Gatu; Kim, Y H; Frenje, J A; Hale, G; Li, C K; Rubery, M; Paris, M; Bacher, A; Brune, C R; Forrest, C; Glebov, V Yu; Janezic, R; McNabb, D; Nikroo, A; Pino, J; Sangster, T C; Séguin, F H; Seka, W; Sio, H; Stoeckl, C; Petrasso, R D

    2016-07-15

    Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of ^{6}Li in low-metallicity stars. Using high-energy-density plasmas we measure the T(^{3}He,γ)^{6}Li reaction rate, a candidate for anomalously high ^{6}Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics. PMID:27472118

  2. Using Inertial Fusion Implosions to Measure the T + 3He Fusion Cross Section at Nucleosynthesis-Relevant Energies

    Zylstra, A. B.; Herrmann, H. W.; Johnson, M. Gatu; Kim, Y. H.; Frenje, J. A.; Hale, G.; Li, C. K.; Rubery, M.; Paris, M.; Bacher, A.; Brune, C. R.; Forrest, C.; Glebov, V. Yu.; Janezic, R.; McNabb, D.; Nikroo, A.; Pino, J.; Sangster, T. C.; Séguin, F. H.; Seka, W.; Sio, H.; Stoeckl, C.; Petrasso, R. D.

    2016-07-01

    Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of 6Li in in low-metallicity stars. Using high-energy-density plasmas we measure the T (3He, ,γ )6Li reaction rate, a candidate for anomalously high 6Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.

  3. Trojan Horse particle invariance for 2H(d,p3H reaction: a detailed study

    Pizzone R.G.

    2014-03-01

    Full Text Available In the last decades the Trojan Horse method has played a crucial role for the measurement of several charged particle induced reactions cross sections of astrophysical interest. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The Trojan Horse nucleus invariance for the binary d(d,pt reaction was therefore tested using the quasi free 2H(6Li, pt4He and 2H(3He,ptH reactions after 6Li and 3He break-up, respectively. The astrophysical S(E-factor for the d(d,pt binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the plane wave approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case.

  4. Trojan Horse particle invariance for 2H(d,p)3H reaction: a detailed study

    Pizzone, R. G.; Spitaleri, C.; Bertulani, C. A.; Mukhamedzhanov, A. M.; Blokhintsev, L.; La Cognata, M.; Lamia, L.; Rinollo, A.; Spartá, R.; Tumino, A.

    2014-03-01

    In the last decades the Trojan Horse method has played a crucial role for the measurement of several charged particle induced reactions cross sections of astrophysical interest. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was therefore tested using the quasi free 2H(6Li, pt)4He and 2H(3He,pt)H reactions after 6Li and 3He break-up, respectively. The astrophysical S(E)-factor for the d(d,p)t binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the plane wave approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case.

  5. Transport properties derived from ion-atom collisions: 6Li-6Li+ and 6Li-7Li+ Cases

    Bouledroua, Moncef; Bouchelaghem, Fouzia; LPR Team

    2014-10-01

    This investigation treats quantum-mechanically the ion- atom collisions and computes the transport coefficients, such as the coefficients of mobility and diffusion. For the case of lithium, the calculations start by determining the gerade and ungerade potential curves through which ionic lithium approaches ground lithium. Then, by considering the isotopic effects and nuclear spins, the elastic and charge-transfer cross sections are calculated for the case of 6Li+and7Li+ colliding with 6Li. Finally, the temperature-dependent diffusion and mobility coefficients are analyzed, and the results are contrasted with those obtained from literature. The main results of this work have been recently published in. This work has been realized within the frames of the CNEPRU Project D01120110036 of the Algerian Ministry of Higher Education.

  6. Feshbach resonances in fermionic 6Li

    Feshbach resonances in 6Li were experimentally studied and theoretically analyzed. In addition to two previously known s-wave resonances, three p-wave resonances were found. Four of these resonances are narrow and yield a precise value of the singlet scattering length. The position of the broad s-wave resonance near 83 mT is mostly sensitive to the triplet potential. It was previously determined in a molecule-dissociation experiment for which we, here, discuss systematic shifts

  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. Thermal neutron detection using a silicon pad detector and 6LiF removable converters

    A semiconductor detector coupled with a neutron converter is a good candidate for neutron detection, especially for its compactness and reliability if compared with other devices, such as 3He tubes, even though its intrinsic efficiency is rather lower. In this paper we show a neutron detector design consisting of a 3 cm × 3 cm silicon pad detector coupled with one or two external 6LiF layers, enriched in 6Li at 95%, placed in contact with the Si active surfaces. This prototype, first characterized and tested at INFN Laboratori Nazionali del Sud and then at JRC Ispra, was successfully shown to detect thermal neutrons with the expected efficiency and an outstanding gamma rejection capability.

  9. Enhancement of the CP-odd effect in the nuclear electric dipole moment of $^6$Li

    Yamanaka, Nodoka

    2015-01-01

    We calculate for the first time the electric dipole moment (EDM) of the $^6$Li nucleus within the alpha + p + n three-body cluster model using the Gaussian expansion method, assuming the one meson exchange P, CP-odd nuclear forces. It is found that the EDM of the $^6$Li is 2 times more sensitive on the isovector pion exchange P, CP-odd nuclear force than the deuteron EDM, due to the CP-odd interaction between the nucleons and the alpha cluster. The $^9$Be EDM is also calculated in the same framework as an alpha + alpha + n three-body system. We also test the ab initio calculation of the EDM of the deuteron, $^3$H and $^3$He nuclei using the realistic Argonne $v18$ nuclear force. In the ab initio calculations, good agreements with previous studies are obtained. We finally discuss the prospects for the new physics beyond the standard model.

  10. Primordial α +d →6Li+γ reaction and second lithium puzzle

    Mukhamedzhanov, A. M.; Shubhchintak, Bertulani, C. A.

    2016-04-01

    During the Big Bang, 6Li was synthesized via the 2H(α ,γ ) 6Li reaction. After almost 25 years of the failed attempts to measure the 2H(α ,γ ) 6Li reaction in the laboratory at Big Bang energies, just recently the LUNA Collaboration presented the first successful measurements at two different Big Bang energies [Anders et al., Phys. Rev. Lett. 113, 042501 (2014), 10.1103/PhysRevLett.113.042501]. In this paper we will discuss how to improve the accuracy of the direct experiment. To this end the photon's angular distribution is calculated in the potential model. It contains contributions from electric dipole and quadrupole transitions and their interference, which dramatically changes the photon's angular distribution. The calculated distributions at different Big Bang energies have a single peak at ˜50∘ . These calculations provide the best kinematic conditions to measure the 2H(α ,γ ) 6Li reaction. The expressions for the total cross section and astrophysical factor are also derived by integrating the differential cross section over the photon's solid angle. The LUNA data are in excellent agreement with our calculations using a potential approach combined with a well established asymptotic normalization coefficient for 6Li→α +d . Comparisons of the available experimental data for the S24 astrophysical factor and different calculations are presented. The Big Bang lithium isotopic ratio 6Li/7Li=(1.5 ±0.3 ) ×10-5 following from the LUNA data and the present analysis are discussed in the context of the disagreement between the observational data and the standard Big Bang model, which constitutes the second lithium problem.

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

    Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr

    2015-05-29

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

  12. Resonances in the proton-6Li scattering

    The differential cross section and the analyzing power of the p+6Li scattering were measured in the laboratory energy range from 1.6 respectively 2.8 MeV to 10 MeV at 45 respectively 40 energies in full angular distributions. The data were subjected both to an analysis in the optical model which yielded already hints to resonance effects and to a comphrehensive scattering-phase analysis for L=0, 1, and 2 under inclusion of channel spin and orbital angular momentum mixings. The consistent description of all data required the assumption of broad resonance structures. An approximate parametrization by a Breit-Wigner formula allowed the estimation of the resonance parameters. (orig./HSI)

  13. 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.

  14. 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

  15. 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...

  16. Enhanced cosmological 6Li abundance as a potential signature of residual dark matter annihilations

    Residual late-time dark matter particle annihilations during and after big-bang nucleosynthesis may alter the predicted cosmological abundances of the light elements. Within the constrained minimal supersymmetric extension of the standard model with a neutralino as the lightest supersymmetric particle, we find negligible effects on the abundances of deuterium, 3He, 4He, and 7Li predicted by homogeneous big-bang nucleosynthesis, but potentially a large enhancement in the predicted abundance of 6Li. This enhancement may be as much as 2 orders of magnitude in the focus-point WMAP strip and in the coannihilation and funnel regions for large tanβ for small m1/2, and the effect is still significant at large m1/2. However, the potential 6Li enhancement is negligible in the part of the coannihilation strip for tanβ=10 that survives the latest LHC constraints. A similar enhancement of the 6Li abundance may also be found in a model with common, nonuniversal Higgs masses (the NUHM1).

  17. Neutron detector based on Particles of 6Li glass scintillator dispersed in organic lightguide matrix

    Most 3He replacement neutron detector technologies today have overlapping neutron–gamma pulse-height distributions, which limits their usefulness and performance. Different techniques are used to mitigate this shortcoming, including Pulse Shape Discrimination (PSD) or threshold settings that suppress all gammas as well as much of the neutrons. As a result, count rates are limited and dead times are high when PSD is used, and the detection efficiency for neutron events is reduced due to the high threshold. This is a problem in most applications where the neutron–gamma separation of 3He detectors had been essential. This challenge is especially severe for neutron coincidence and multiplicity measurements that have numerous conflicting requirements such as high detection efficiency, short die-away time, short dead time, and high stability. 6Li-glass scintillators have excellent light output and a single peak distribution, but they are difficult to implement because of their gamma sensitivity. The idea of reducing the gamma sensitivity of 6Li-glass scintillators by embedding small glass particles in an organic light-guide medium was first presented by L.M. Bollinger in the early 60s but, to the best of our knowledge, has never been reduced to practice. We present a proof of principle detector design and experimental data that develop this concept to a large-area neutron detector. This is achieved by using a multi-component optical medium (6Li glass particles attached to a glass supporting structure and a mineral oil light guide) which matches the indices of refraction and minimizes the absorption of the 395 nm scintillator light. The detector design comprises a 10 in. long tube with dual end readout with about 3% volume density of 6Li glass particles installed. The presented experimental data with various neutron and gamma sources show the desired wide gap between the neutron and gamma pulse height distributions, resulting in a true plateau in the counting

  18. Neutron detector based on Particles of 6Li glass scintillator dispersed in organic lightguide matrix

    Ianakiev, K. D.; Hehlen, M. P.; Swinhoe, M. T.; Favalli, A.; Iliev, M. L.; Lin, T. C.; Bennett, B. L.; Barker, M. T.

    2015-06-01

    Most 3He replacement neutron detector technologies today have overlapping neutron-gamma pulse-height distributions, which limits their usefulness and performance. Different techniques are used to mitigate this shortcoming, including Pulse Shape Discrimination (PSD) or threshold settings that suppress all gammas as well as much of the neutrons. As a result, count rates are limited and dead times are high when PSD is used, and the detection efficiency for neutron events is reduced due to the high threshold. This is a problem in most applications where the neutron-gamma separation of 3He detectors had been essential. This challenge is especially severe for neutron coincidence and multiplicity measurements that have numerous conflicting requirements such as high detection efficiency, short die-away time, short dead time, and high stability. 6Li-glass scintillators have excellent light output and a single peak distribution, but they are difficult to implement because of their gamma sensitivity. The idea of reducing the gamma sensitivity of 6Li-glass scintillators by embedding small glass particles in an organic light-guide medium was first presented by L.M. Bollinger in the early 60s but, to the best of our knowledge, has never been reduced to practice. We present a proof of principle detector design and experimental data that develop this concept to a large-area neutron detector. This is achieved by using a multi-component optical medium (6Li glass particles attached to a glass supporting structure and a mineral oil light guide) which matches the indices of refraction and minimizes the absorption of the 395 nm scintillator light. The detector design comprises a 10 in. long tube with dual end readout with about 3% volume density of 6Li glass particles installed. The presented experimental data with various neutron and gamma sources show the desired wide gap between the neutron and gamma pulse height distributions, resulting in a true plateau in the counting

  19. The evaluation of cross sections for n + 6Li reaction

    Neutron nuclear data of 6Li are important for fusion neutronics calculation. Therefore, the cross sections for n + 6Li reaction are evaluated in the energy range from 10-5 eV to 20 MeV. In the evaluation, 6Li(n, d+n)4He and 6Li(n, n+d)4He reactions are included. It is concluded that there is really only the second excited level (3.562 MeV) in the inelastic scattering, no assumed levels were taken into account. The evaluated data describe the real process of n + 6Li reactions and improve the existing evaluated libraries such as ENDF/B-6 and JENDL-3

  20. 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

  1. Study of the {sup 3} He(d, p){sup 4} He reaction through the Trojan Horse Method

    La Cognata, M. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Musumarra, A. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Spitaleri, C. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy)] (and others)

    2005-07-25

    The astrophysically relevant {sup 3} He(d, p){sup 4} He reaction was indirectly studied by means of the Trojan Horse Method applied to the {sup 6} Li({sup 3} He, p{alpha}){sup 4} He three body process performed at 5 and 6 MeV. The bare astrophysical S(E)-factor extracted in Modified Plane Wave Born Approximation was compared with the free behaviour and an independent estimate of the screening potential was obtained, confirming the discrepancy with the adiabatic limit.

  2. 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

  3. Studies of the D state of 6Li using the FSU polarized 6Li Beam

    One way to quantify the D-state component of the wave function of a nucleus is by the quantity η, the ratio of the D- and S-state asymptotic normalization constants. Analyses of the analyzing powers from transfer reactions induced by polarized ions have been useful for the determination of η in the A=2-4 systems. In an effort to determine η for the d+α relative motion in 6Li we have measured analyzing powers for (6L rvec i,d) reactions on 58Ni and 40Ca at E(6Li)=34 and h;MeV. The experiments were performed at Florida State University using the Optically Pumped Polarized Lithium Ion Source. We compared the data with the results of well-constrained DWBA calculations assuming a direct α-particle transfer mechanism. With η the only free parameter in the calculations, a best fit to the tensor analyzing power data results in an average value of η=+0.0003±0.0009, much smaller than previous determinations. copyright 1999 American Institute of Physics

  4. 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

  5. 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

  6. X particle effect for 6Li reaction rates calculations

    The inferred primordial 6Li-7Li abundances are different from standard big bang nucleosynthesis results, 6Li is 1000 times larger and 7Li is 3 times smaller than the big bang prediction. In big bang nucleosynthesis, negatively charged massive X particles a possible solution to explain this primordial Li abundances problem [1]. In this study, we consider only X particle effect for nuclear reactions to obtain S-factor and reaction rates for Li. All S-factors calculated within the Optical Model framework for d(α,γ)6Li system. We showed that the enhancement effect of massive negatively charged X particle for 6Li system reaction rate.(author)

  7. 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.

  8. 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.)

  9. 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

  10. 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

  11. 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)

  12. 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

  13. 6^Li in the atmosphere of GJ 117 Revisited

    Christian, D J; Jevremovic, D

    2008-01-01

    Detection of 6^Li has been shown for energetic solar events, one chromospherically active binary, and several dwarf halo stars. We had previously found a 6^Li/7^Li = 0.03+/-0.01 for active K dwarf GJ 117 using VLT UVES observations. Here we present high signal-to-noise (>1000) high spectral resolution observations taken with the McDonald Observatory's 2.7m and echelle spectrometer of GJ 117. We have used the solar spectrum and template stars to eliminate possible blends, such as Ti I, in the 6^Li spectral region. Our new analysis, using an updated PHOENIX model atmosphere finds 6^Li/7^Li = 0.05+/-0.02. Additionally, bisector analysis showed no significant red asymmetries that would affect the lithium line profile. No changes above the statistical uncertainties are found between the VLT and McDonald data. The amount of 6^Li derived for GJ 117 is consistent with creation in spallation reactions on the stellar surface, but we caution that uncertainties in the continuum level may cause additional uncertainty in t...

  14. 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.)

  15. 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

  16. CDCC calculations of elastic scattering for the systems 6Li+144Sm and 6Li+208Pb. Effect of resonances of 6Li on elastic scattering angular distributions

    Calculations of elastic scattering angular distributions for reactions of the weakly bound projectile 6Li with targets 144Sm and 208Pb at energies above the barrier, are performed with the Continuum Discretized Coupled-Channel method (CDCC). Ground, resonant and nonresonant continuum states of 6Li are included up to some maximum energy εmax for which convergence is achieved. In the three-body system, global interactions are used for the α-target and d - target sub-systems. The effect of continuum resonant states of 6Li, i.e., l = 2, jπ = 3+, 2+ and 1+ on elastic scattering angular distributions is investigated by extracting these states from the continuum space. It is found that the calculated elastic scattering angular distributions are in good agreement with the measurements for most of the cases studied where consideration of couplings to continuum states is essential. It is also found that the resonance character of the continuum states is in some cases important to obtain agreement with the data

  17. 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).

  18. Sequential mechanism for the Li7 (He3, α)6 Li(d)α reaction at incident energy between 2.5 and 11.5 MeV

    A strictly sequential mechanism appears to appropriate for the Li7 (3He,α)6Li(d)α reaction in the energy range between 2.5 and 11.5 MeV. It can be described by a first direct emission mechanism and a second delayed emission

  19. H-2, H-3, He-3 production in solar flares. [using updated cross sections and kinematics

    Ramaty, R.; Kozlovsky, B.

    1974-01-01

    The production of deuterium, tritium, and helium-3 from nuclear reactions of accelerated charged particles is evaluated with the ambient solar atmosphere. Updated cross sections and kinematics are used, calculations are extended to very low energies (approximates 0.1 MeV/nucleon), and the angular distribution of the secondary particles is calculated. The calculations are compared with data on accelerated isotopes from solar flares. In particular, the August 1972 events are considered for which both He-3 and nuclear gamma rays were observed. An explanation for He-3-rich events is provided in terms of the angular distributions of secondary isotopes, and the flux of 2.2 MeV gamma rays from such flares are also predicted.

  20. 6Li-doped silicate glass for thermal neutron shielding

    Glass formulations are described that contain high concentrations of 6Li and are suitable for use as thermal neutron shielding. One formulation contained 31 mol% of 6Li2O and 69 mol% of SiO2. Studies were performed on a second formulation that contained as much as 37 mol% of 6Li2O and 59 mol% of SiO2, with 4 mol% Al2O3 added to prevent crystallization at such high 6Li2O concentrations. These lithium silicate glasses can be formed into a variety of shapes using conventional glass fabrication techniques. Examples include flat plates, disks, hollow cylinders, and other more complex geometries. Both in-beam and in-core experiments have been performed to study the use and durability of Li silicate glasses. In-core experiments show the glass can withstand the intense radiation fields near the core of a reactor. The neutron attenuation of the glasses used in these studies was 90%/mm. In-beam studies show that the glass is effective for reducing the gamma-ray and neutron fields near experiments. ((orig.))

  1. Reaction mechanisms in the 6Li+ 52Cr system

    Pandey Bhawna

    2015-01-01

    Full Text Available Reactions induced by the weakly bound 6Li projectile interacting with the intermediate mass target 52Cr are investigated. The choice of this particular reaction in our study is because it is proposed as a surrogate reaction [6Li(52Cr, d56Fe*] for the measurement of 55Fe(n,p reaction cross-section, which has been found to be very important in fusion reactor studies. All the conditions which have to be satisfied for using the surrogate method have been checked. The energy of 6Li beam is selected in a way so as to get equivalent neutron energy in the region of 9-14 MeV, which is of primary interest in fusion reactor application. In the present work, statistical model calculations PACE (Projection-Angular-Momentum-Coupled-Evaporation, ALICE and Continuum-Discretized–Coupled-Channel (CDCC: FRESCO have been used to provide information for the 6Li + 52Cr system and the respective contributions of different reaction mechanisms. The present theoretical work is an important step in the direction towards studying the cross-section of the 55Fe(n, p55Mn reaction by surrogate method.

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. Unusual Threshold Anomaly in the 6Li+208Pb System

    ZHANG Chun-Lei; JIA Hui-Ming; WU Zhen-Dong; XU Xin-Xing; BAI Chun-Lin; ZHANG Huan-Qiao; LIN Cheng-Jian; RUAN Ming; LIU Zu-Hua; YANG Feng; WU Xiu-Kun; ZHOU Ping; AN Guang-Peng

    2006-01-01

    @@ The angular distributions of elastic scattering for the 6Li +208Pb system have been measured at several energies around the Coulomb barrier. The parameters of optical potential are extracted by means of a phenomenological optical model analysis. It is found that the real and imaginal potentials show a pronounced energy dependence.The behaviour of the potential at the nearly especially sub-barrier energies in the 6Li+208Pb system is quite different from the results of some previous reports observed in other systems, such as 19 F +208 Pb and 16 O+208 Pb.This unusual threshold phenomenon indicates that breakup channel is strongly coupled with the elastic channel and has obvious effects on optical potential.

  8. Feshbach resonances in mixtures of 6Li and 40K

    We report on the measurement of Feshbach resonances in Fermi-Fermi mixtures. For this purpose we have created an ultracold mixture of the fermionic alkali isotopes 6Li and 40K in an optical dipole trap. In the same trap we have realized a three-component degenerate spin mixture of 40K -atoms at T 0.3TF. To create the mixture we start by loading a two-species magneto-optical trap (MOT) from two separate 2D-MOT sources. We realized for the first time a 2D-MOT source for lithium, yielding a large cold flux of up to 109 s-1. The mixture is then captured in an optically-plugged magnetic quadrupole trap. After sympathetic cooling of 6Li by 40K to T∝10μK the mixture is loaded into optical tweezers. The mixture is optically transported over a distance of 21.5 cm into a science cell where we measure Feshbach resonances using magnetic field coils designed for high homogeneity. We report on our progress measuring the width of Feshbach resonances in 6Li -40K mixtures and locating resonances in mixtures of 40K.

  9. Study of the {sup 9}Be(p,{alpha}){sup 6}Li reaction via the Trojan Horse Method

    Romano, S.; Lamia, L.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Tumino, A. [INFN, Laboratori Nazionali del Sud, Catania (Italy); Universita di Catania, Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Catania (Italy); Li, C.; Pizzone, R.G. [INFN, Laboratori Nazionali del Sud, Catania (Italy)

    2006-03-15

    The Trojan Horse Method has been applied to the {sup 2}H({sup 9}Be,{sup 6}Li{alpha})n three-body reaction in order to investigate the {sup 9}Be(p,{alpha}){sup 6}Li two-body reaction, which is involved in the study of light element abundances (lithium, beryllium and boron). A coincidence measurement was performed in order to identify the presence of the quasi-free mechanism in the three-body reaction, needed for the application of the method. The astrophysical S(E)-factor was extracted and compared to direct data. No information about electron screening effects can be extracted due to the poor resolution of the indirect data. (orig.)

  10. 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.

  11. Neutron spectrometry using artificial neural networks for a Bonner sphere spectrometer with a 3He detector

    Neutron spectra unfolding and dose equivalent calculation are complicated tasks in radiation protection, are highly dependent of the neutron energy, and a precise knowledge on neutron spectrometry is essential for all dosimetry-related studies as well as many nuclear physics experiments. In previous works have been reported neutron spectrometry and dosimetry results, by using the artificial neural networks (Ann) technology as alternative solution, starting from the count rates of a Bonner spheres system with a 6LiI(Eu) thermal neutrons detector, 7 polyethylene spheres and the UTA4 response matrix with 31 energy bins. In this work, an Ann was designed and optimized by using the RDAnn methodology for the Bonner spheres system used at CIEMAT Spain, which is composed of a 3He neutron detector, 12 moderator spheres and a response matrix for 72 energy bins. For the Ann design process a neutrons spectra catalogue compiled by the IAEA was used. From this compilation, the neutrons spectra were converted from lethargy to energy spectra. Then, the resulting energy fluence spectra were re-bin ned by using the MCNP code to the corresponding energy bins of the 3He response matrix before mentioned. With the response matrix and the re-bin ned spectra the counts rate of the Bonner spheres system were calculated and the resulting re-bin ned neutrons spectra and calculated counts rate were used as the Ann training data set. (Author)

  12. 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

  13. Measurement of the 2H(d ,p ) 3H reaction at astrophysical energies via the Trojan-horse method

    Li, Chengbo; Wen, Qungang; Fu, Yuanyong; Zhou, Jing; Zhou, Shuhua; Meng, Qiuying; Spitaleri, C.; Tumino, A.; Pizzone, R. G.; Lamia, L.

    2015-08-01

    The study of the 2H(d ,p ) 3H reaction is very important for the nucleosynthesis in both the standard Big Bang and stellar evolution, as well as for the future fusion reactor's planning of energy production. The 2H(d ,p ) 3H bare nucleus astrophysical S (E ) factor has been measured indirectly at energies from about 400 keV down to several keV by means of the Trojan-horse method applied to the quasifree process 2H(6Li ,p t ) 4He induced at a lithium beam energy of 9.5 MeV, which is closer to the zero-quasifree-energy point. An accurate analysis leads to the determination of the Sbare(0 ) =56.7 ±2.0 keV b and of the corresponding electron screening potential Ue=13.2 ±4.3 eV. In addition, this work gives an updated test for the Trojan-horse nucleus invariance by comparing with previous indirect investigations using the 3He=(d +p ) breakup.

  14. 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.

  15. 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

  16. 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

  17. 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)

  18. Tensor polarization of 6Li*(2.186 MeV, 3+) in the 9Be(p,α)6Li reaction at 40 MeV

    Tensor moments tkq have been determined for the 6Li*(2.186 MeV, 3+) state produced in the 9Be(p,α1)6Li reaction at 40 MeV. Angular correlation measurements were made between α1 and the α-particle or deuteron fragment from the breakup of 6Li*. Comparison of the tkq are made with the predictions of a model that includes direct and exchange processes. Angular distributions of the differential cross sections for the 9Be(p,α)6Li reaction for the g.s. and first two excited states are presented. (orig.)

  19. Resonant and nonresonant Coulomb break up of 6Li

    The resonant and nonresonant cross section for break up of 6Li in the Coulomb field of a heavy nucleus is theoretically studied on the basis of a DWBA approach and analysed in view of a possible experimental access to electromagnetic transition matrix elements between the ground state of the projectile and α+d continuum states at small relative energies. The calculation explicitly uses some simplifications appearing in the particular case of quadrupole transitions which dominate the considered case. Various sensitivities of the cross sections are discussed. (orig.)

  20. 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

  1. 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

  2. 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

  3. 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.

  4. Ab initio no-core solutions for $^6$Li

    Shin, Ik Jae; Maris, Pieter; Vary, James P; Forssén, Christian; Rotureau, Jimmy; Michel, Nicolas

    2016-01-01

    We solve for properties of $^6$Li in the ab initio No-Core Full Configuration approach and we separately solve for its ground state and $J^{\\pi}=2_{2}^{+}$ resonance with the Gamow Shell Model in the Berggren basis. We employ both the JISP16 and chiral NNLO$_{opt}$ realistic nucleon-nucleon interactions and investigate the ground state energy, excitation energies, point proton root-mean-square radius and a suite of electroweak observables. We also extend and test methods to extrapolate the ground state energy, point proton root-mean-square radius, and electric quadrupole moment. We attain improved estimates of these observables in the No-Core Full Configuration approach by using basis spaces up through N$_{max}$=18 that enable more definitive comparisons with experiment. Using the Density Matrix Renormalization Group approach with the JISP16 interaction, we find that we can significantly improve the convergence of the Gamow Shell Model treatment of the $^6$Li ground state and $J^{\\pi}=2_{2}^{+}$ resonance by ...

  5. Photoassociative creation of ultracold heteronuclear 6Li40K* molecules

    Ridinger, Armin; Salez, Thomas; Fernandes, Diogo Rio; Bouloufa, Nadia; Dulieu, Olivier; Salomon, Christophe; Chevy, Frederic

    2011-01-01

    We investigate the formation of weakly bound, electronically excited, heteronuclear 6Li40K* molecules by single-photon photoassociation in a magneto-optical trap. We performed trap loss spectroscopy within a range of 325 GHz below the Li(2S_(1/2))+K(4P_(3/2)) and Li(2S_(1/2))+K(4P_(1/2)) asymptotic states and observed more than 60 resonances, which we identify as rovibrational levels of 7 of 8 attractive long-range molecular potentials. The long-range dispersion coefficients and rotational constants are derived. We find large molecule formation rates of up to ~3.5x10^7s^(-1), which are shown to be comparable to those for homonuclear 40K_2*. Using a theoretical model we infer decay rates to the deeply bound electronic ground-state vibrational level X^1\\Sigma^+(v'=3) of ~5x10^4s^(-1). Our results pave the way for the production of ultracold bosonic ground-state 6Li40K molecules which exhibit a large intrinsic permanent electric dipole moment.

  6. Measurement of differential cross section for the 6Li(n,t)4He reaction by using gridded ionization chamber

    By using a gridded ionization chamber, the differential cross sections and angle integrated cross sections for the 6Li(n,t)4He reaction were measured at neutron energies of 3.67 and 4.42 MeV. The neutrons were produced through D(d,n)3He reaction by a deuteron gas target. Absolute neutron flux was determined through 238U(n,f) and H(n,p) reactions. At 3.67 MeV the differential cross section for triton is almost 90 degree symmetric but it is obviously forward peaked at 4.42 MeV in the center-of-mass reference system

  7. 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

  8. ZnS/6Li scintillation material as an alternative to 6Li-glass scintillators for neutron detection in time focusing geometry

    As an alternative of using 6Li-glass scintillators for neutron detection in time focusing geometry the effects of ZnS/6Li scintillation material on the measuring efficiency will be discussed on example of the high resolution RTOF device FSS at GKSS Geesthacht, Germany. ((orig.))

  9. Novel 4{pi} Detection System for the Measurement of the {sup 6}Li(n,{alpha}){sup 3}H Reaction Cross Section

    Giorginis, Georgios; Bencardino, Raffaele [European Commission, Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Geel (Belgium)

    2011-12-13

    A dedicated one-dimensional Time Projection Chamber (1D-TPC) was designed and produced at IRMM to determine the {sup 6}Li(n,{alpha}){sup 3}H cross section in the 0.4-2.8 MeV energy range, aiming at 5% accuracy. The basic TPC components were a twin gridded ionisation chamber (GIC) with interwired electrodes and fast digitisation of the anode and cathode signals. The energy of both reaction products emitted from a thin {sup 6}LiF sample at the common TPC cathode was measured. A Kr(97%)CO{sub 2}(3%) mixture was used as the detector gas at a pressure up to 3.5 bar. A {sup 238}U sample mounted on the cathode of an ionisation chamber without grid was used as the neutron flux monitor. Special care was taken to reduce the experimental sources of uncertainty. The beam-monitor {sup 238}U sample was characterised at IRMM by low-geometry {alpha}-counting with an accuracy of 0.1%. A {sup 6}Li sample was produced at IRMM by vacuum evaporation of {sup 6}LiF onto transparent aluminium backing. The number of {sup 6}Li atoms will be measured via Thermal Neutron Depth Profiling with an expected accuracy of 2% with respect to an IRMM Standard Reference Material. First test measurements were performed using a monoenergetic neutron beam produced by the T(p,n){sup 3}He reaction at the IRMM 7 MV Van de Graaff accelerator. The experimental method and preliminary results are presented.

  10. 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.

  11. A Cluster Model of ^6He and ^6Li

    Armstrong, Jeremy; Sakharuk, Alexander; Zelevinsky, Vladimir

    2007-10-01

    Small nuclei provide an ideal testing ground of few-body theories. ^6He is particularly interesting in that it shows an extended particle distribution similar to a halo nucleus, is loosely bound, and is a Borromean system. We apply the Brink Formalism in secondary quantization to study the structure of ^6He. This formalism allows for the proper treatment of Fermi statistics and correct projection into eigenstates of angular momentum. The alpha plus dineutron configuration and ``cigar'' (neutron, alpha, neutron chain) configuration were studied to obtain binding energies, charge radii, matter radii, and B(E2) for ^6He. The same configurations were used to obtain the same observables for ^6Li. We were then able to calculate the log ft value for the beta decay of ^6He. We now examine the effects of different nucleon-nucleon interactions on our systems.

  12. Neutron spectrum measurements in CFRMF by 6Li spectrometry

    The neutron energy spectrum of the Couples Fast Reactivity Measurements Facility (CFRMF) has been measured by the 6Li(n,α)t spectrometry technique between the energies of 10 keV and 8 MeV. These measurements were made in order to improve the knowledge of this benchmark neutron field as related to dosimetry and other integral cross sections. Energy spectra of both the α + t and t responses were obtained simultaneously using two-parameter multichannel pulse height analysis. Spectrometers of different design and resolution characteristics were applied. The data were reduced using recently evaluated cross section information. The results are compared with the neutron spectrum calculated using recently evaluated cross section information. (author)

  13. 6Li electromagnetic form factors and phenomenological cluster models

    The longitudinal form factors of the ground and 2.18 MeV (3+, T = 0) states, and the transverse form factors of the 3.56 MeV (0+, T = 1) and 5.37 MeV (2+, T = 1) states of 6Li are compared with the predictions based on fully antisymmetrized α-d and t-tau cluster models. The longitudinal form factors are adequately described by the α-d model, but the transverse form factors seem to be more consistent with a t-tau model which is close to the shell-model limit. Estimates are made for the ground state t and α spectroscopic factors. The 3.56 MeV M1 transition current density is calculated for both models and compared with experiment. (Auth.)

  14. 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...

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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)

  20. 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.

  1. 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.

  2. 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...

  3. 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 ...

  4. 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

  5. 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)

  6. 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

  7. 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

  8. 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

  9. 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

  10. Quantum effects in the case of (6)Li+ and (7)Li+ ions evolving in a neutral (6)Li gas at a wide range of temperatures.

    Bouchelaghem, F; Bouledroua, M

    2014-02-01

    This work deals with the quantum-mechanical calculation of the temperature-dependent mobility of ionic lithium atoms diffusing in their parent gas. The computation of the quantal phase shifts in connection with the gerade and ungerade potential-energy curves, through which Li(+) approaches Li(2s), leads to the computation of the charge-transfer and diffusion cross sections. The behavior of the coefficients of diffusion and mobility with temperature is also examined. Throughout this work, the isotopic effects in the (6)Li(+)-(6)Li and (7)Li(+)-(6)Li collisions are emphasized. PMID:24326775

  11. 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...

  12. Ultracold neutron detection with 6Li-doped glass scintillators, NANOSC: a fast ultracold neutron detector for the nEDM experiment at the Paul Scherrer Institute

    Ban, G; Bodek, K; Chowdhuri, Z; Geltenbort, P; Griffith, W C; Hélaine, V; Henneck, R; Kasprzak, M; Kermaidic, Y; Kirch, K; Komposch, S; Koss, P A; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Musgrave, M; Naviliat-Cuncic, O; Piegsa, F M; Pierre, E; Pignol, G; Quéméner, G; Rawlik, M; Ries, D; Rebreyend, D; Roccia, S; Rogel, G; Schmidt-Wellenburg, P; Severijns, N; Wursten, E; Zejma, J; Zsigmond, G

    2016-01-01

    This paper summarizes the results from measurements aiming to characterize ultracold neutron detection with 6Li-doped glass scintillators. Single GS10 or GS20 scintillators, with a thickness of 100-200 micrometer, fulfill the ultracold neutron detection requirements with an acceptable neutron-gamma discrimination. This discrimination is clearly improved with a stack of two scintillators: a 6Li-depleted glass bonded to a 6Li-enriched glass. The optical contact bonding is used between the scintillators in order to obtain a perfect optical contact. The scintillator's detection efficiency is similar to that of a 3He Strelkov gas detector. Coupled to a digital data acquisition system, counting rates up to a few 10^5 counts/s can be handled. A detector based on such a scintillator stack arrangement was built and has been used in the neutron electric dipole moment experiment at the Paul Scherrer Institute since 2010. Its response for the regular runs of the neutron electric dipole moment experiment is presented.

  13. Astrophysical S-factors of radiative capture of protons on 2H, 3H, 6Li and 12C nuclei

    Dubovichenko, S. B.; Dzhazairov-Kakhramanov, A. V.

    2010-01-01

    We have considered the possibility to describe the astrophysical S-factors of some light atomic nuclei on the basis of the potential cluster model by taking into account the supermultiplet symmetry of wave functions and splitting the orbital states according to Young's schemes. Such an approach allows analyzing the structure of inter-cluster interactions, to determine the presence of allowed and forbidden states in the interaction potential and so the number of nodes of the orbital wave funct...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. The Proton- 3He - And α-Particle-Induced Nuclear Reactions At Low And Extremely Low Energies For Astrophysics

    Full text: The present report is devoted to brief discussion of the following subjects. The modern methods of definition of nuclear vertex constants (NVC) (or respective asymptotic normalization coefficients (ANC)): a) the modified DWBA; b) the modified two-body potential approach for direct radiative b(c, γ )c capture reactions. About accuracy of the available 'indirectly' measured values of the NVC's and ANC's for the specific nuclei such as 3He,6,7Li, 7Be, 8B, 13,14N and 17F obtained by different methods. Use of ANCs for determination of the astrophysical S factors of the radiative capture A(p,γ )B and A(α, γ)B reactions relevant for astrophysics. About prospects of using of the available experimental facilities of INP (Almaty, Kazakhstan), RIAP (Tashkent, Uzbekistan) and CNRTC (Istanbul, Turkey) for the precise measurements of the radiative capture 6Li(p,γ )7Be, d(α,γ )6Li and 10B(p, γ)11C and 12C(p, γ)13N and A(α, γ)B reactions relevant for astrophysics. (authors)

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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)

  9. 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.))

  10. 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

  11. 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.)

  12. 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.

  13. 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...

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

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

    2012-01-01

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

  15. Towards 6Li-40K ground state molecules

    The production of a quantum gas with strong long - range dipolar interactions is a major scientific goal in the research field of ultracold gases. In their ro - vibrational ground state Li-K dimers possess a large permanent dipole moment, which could possibly be exploited for the realization of such a quantum gas. A production of these molecules can be achieved by the association of Li and K at a Feshbach resonance, followed by a coherent state transfer. In this thesis, detailed theoretical an experimental preparations to achieve state transfer by means of Stimulated Raman Adiabatic Passage (STIRAP) are described. The theoretical preparations focus on the selection of an electronically excited molecular state that is suitable for STIRAP transfer. In this context, molecular transition dipole moments for both transitions involved in STIRAP transfer are predicted for the first time. This is achieved by the calculation of Franck-Condon factors and a determination of the state in which the 6Li-40K Feshbach molecules are produced. The calculations show that state transfer by use of a single STIRAP sequence is experimentally very well feasible. Further, the optical wavelengths that are needed to address the selected states are calculated. The high accuracy of the data will allow to carry out the molecular spectroscopy in a fast and efficient manner. Further, only a comparatively narrow wavelength tuneability of the spectroscopy lasers is needed. The most suitable Feshbach resonance for the production of 6Li-40K molecules at experimentally manageable magnetic field strengths is occurring at 155 G. Experimentally, this resonance is investigated by means of cross-dimensional relaxation. The application of the technique at various magnetic field strengths in the vicinity of the 155 G Feshbach resonance allows a determination of the resonance position and width with so far unreached precision. This reveals the production of molecules on the atomic side of the resonance

  16. 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

  17. 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.)

  18. 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.

  19. 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)

  20. 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...

  1. 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 ...

  2. 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.

  3. 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

  4. 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)

  5. 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.

  6. 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

  7. 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)

  8. 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.)

  9. Development of {sup 6}LiF thermal neutron shield for PGNAA

    Kim, M. S.; Park, J. H.; Hong, K. W.; Jun, B. J. [KAERI, Taejon (Korea, Republic of); Bun, S. H.; Choi, H. D. [Seoul National Univ., Seoul (Korea, Republic of)

    2001-05-01

    The {sup 6}LiF tile which will be utilized as the neutron shield of the gamma ray detector at the prompt gamma neutron activation analysis facility of KAERI-HANARO is developed. The {sup 6}LiF powder is obtained by the reaction of hydrofluoric acid with the {sup 6}Li{sub 2}CO{sub 3} powder, and the yield of the {sup 6}LiF is 86% of the theoretical value. In order to fabricate the stable tile from toxic and irritant LiF powder, the optimum sintering procedure is developed using the LiF powder with naturally abundant {sup 6}Li. The sintering temperature is 720 .deg. C, and the heating rate is 120 .deg. C/h. The preliminary heating process at 500 .deg. C is added in fabricating the {sup 6}LiF tile. The density of fabricated LiF tile is 2.4{approx}2.5 g/cm{sup 3}, and it is above 90% of theoretical density. The density of fabricated {sup 6}LiF tile is 2.25 g/cm{sup 3}, and the neutron transmission rate is below 10{sup -8}, so the thermal neutron transmission is negligible. Therefore, the tile is confirmed to be useful for PGNAA facility.

  10. Electroexcitation of the 0+ (3.562 MeV) level of 6Li and its application to the reaction 6Li(γ,π+)6He

    The M1 form factor for the 0+ (3.562 MeV, T=1) level in 6Li has been measured in the momentum transfer range q=0.26-1.15 fm-1. The radiative width is found to be GAMMAsub(γ0)=8.16+-0.19eV by extrapolation to the photon point. Phenomenological configuration amplitudes have been obtained for the ground and 3.562 MeV level, and it is shown that the 1p harmonic oscillator radial wave functions do not give a good description of the inelastic form factor. The results have been applied to the reaction 6Li(γ,π+)6He near threshold. The theoretical cross section is 24% higher than the data. The muon capture rate in 6Li and Fsub(A)(0) are also evaluated. (Auth.)

  11. Direct measurement of the spin-dependent capture and scattering of slow neutrons by 6Li

    The spin-dependent capture cross section sigma/sup c//sub +/-sigma/sup c//sub -/ of slow neutrons (lambda = 1.074 A) by 6Li has been determined from the flipping ratio of a transmitted polarized neutron beam as a function of 6Li polarization. We used two methods, one of which also enabled us to measure the spin-dependent scattering length b/sub +/-b/sub -/ of 6Li. We find sigma/sub +//sup c/-sigma/sub -//sup c/ = -1170 +- 50 b and b/sub +/-b/sub -/ = (-0.38 +- 0.05) x 10-12 cm

  12. Spin-dipole excitations of 6Li in charged pion photoproduction

    In the framework of bound shell model the photoproduction cross sections of charged pions on 6Li are calculated when spin-isospin dipole resonance is excited. It is shown that the transition strenqth concentrates in several energy regions. Such a gross-structure of the excitation spectrum is gaverned by the confiqurational splittinq of the resonance. The excitation spectrum in 6Li(γ, π)-reaction is compared with the 6Li(π, γ), (e, e') and (n, p) reaction spe;tra where spin-isospin transitions are dominating too

  13. Effect of the breakup process on the direct reaction with a 6Li projectile

    We investigate the effect of the breakup process on the direct reaction (DR) for 6Li. In order to study this effect, we introduce the experimental and semiexperimental ratio factors Rexpt and Rth by using the semiexperimental and experimental α-production cross sections and DR cross sections. The average values of the ratio Rexpt (Rth) for the 6Li+208Pb and 6Li+209Bi systems are 0.90 (0.91) and 0.86 (0.85), respectively. From these results, it can be seen that the α-production cross sections are the main contribution to the DR cross sections.

  14. 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

  15. 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.

  16. 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.)

  17. 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.)

  18. 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)).

  19. 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)

  20. 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.))

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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.)

  6. 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.

  7. 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.)

  8. 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

  9. 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)

  10. 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.

  11. 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 ...

  12. 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.

  13. 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 ...

  14. 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.

  15. 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

  16. 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)

  17. Diffraction proton scattering on 6Li nucleus and its cluster structure

    Elastic and inelastic scattering of 600 and 1040 MeV protons on 6Li nucleus without suggesting equality of pp-and pn-amplitudes of elastic scattering are investigated within the frames of diffraction approximation. Parameters of 6Li nucleus wave functions, parameters of amplitude of elastic NN scattering at given proton energies are given, differential cross sections of elastic and inelastic proton scattering with excitation of 3+ level for four types of 6Li wave functions are presented graphically. It is obvious from the given calculations that none of the simplest 6Li wave functions can explain the present experimental data. The whole complex of experimental data on elastic and inelastic proton scattering cannot be explained within the frames of a simple αd cluster model using known at present sets of parameters of elastic NN scattering amplitude

  18. 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.

  19. Effects of nuclear breakup channel on fusion of 6Li+64Zn system around barrier energies

    We have studied the effects of breakup, occurring due to the nuclear interaction between weakly bound 6Li and tightly bound 64Zn isotopes, on the fusion reaction at near barrier energies within the framework of dynamic polarization potential (DPP) approach. When the nuclear induced dynamic polarization potential is taken into account sub barrier enhancement and above barrier suppression have been found which improves the matching between the fusion excitation function data and predictions for 6Li+64Zn system significantly. (author)

  20. Multi-particle correlation effect at intermediate-energy proton scattering by 6Li

    In the framework of the Glauber-Sitenko theory study is made of the elastic proton scattering by 6Li at the energy of 0.6 and 1.04 GeV using the realistic phenomenological wave functions for different sets of parameters of the elastic scattering NN-amplitudes. An essential cross-sections on a form of the 6Li wave function is shown

  1. Lines in the spectrum of 6LiH (2985--5158 A)

    The emission spectra of the A1Σ+--X1Σ+ bands of 6LiH were photographed in the 2985 - 5158 A region with a 3.4 meter Ebert Spectrograph of theoretical resolution of about 0.07 cm-1. High-purity 6LiH crystals were obtained from Oak Ridge National Laboratory. The atomic percent of 6Li in 6LiH was 95.58 percent. The discharge source was a demountable stainless steel hollow cathode lamp. The lithium hydride crystals were packed into the cathode. Pressure in the discharge tube was about 10 to 20 torr of H2. The disharge was run at about 600 volts and 1.25 to 1.75 amperes. Acceptable spectra were obtained with exposure time of 6 hours. A Westinghouse iron hollow cathode was used to produce the iron spectrum for calibration. The plates were measured on the Gaertner photoplate comparator with an encoder system and on-line computer service at Argonne National Laboratory. The measured lines in the spectra of 6LiH are given in this report (COO-2326-17). Similar spectra for 6LiD and 7LiH are given in companion reports (COO-2326-18) and (COO-2326-19), respectively. The relative intensities of the lines are applicable only to short regions and do not extend over the whole spectrum

  2. Lines in the spectrum of 6LiD (3086--5156 A)

    The emission spectra of A1Σ+--X1Σ+ bands of 6LiD were photographed in the 3086 A - 5156 A region with a 3.4 meter Ebert Spectrograph of theoretical resolution of about 0.07 cm-1. High-purity 6LiD crystals were obtained from Oak Ridge National Laboratory. The atomic percent of 6Li in 6LiD was 95.58 percent. The discharge source is a demountable stainless steel hollow cathode lamp. The lithium deuteride crystals were packed into the cathode. Pressure in the discharge tube was about 10 to 20 torr of D2. The discharge was run at about 600 volts and 1.25 to 1.75 amperes. Acceptable spectra were obtained with exposure time of 6 hours. A Westinghouse iron hollow cathode was used to produce the iron spectrum for calibration. The plates were measured on the Gaertner photoplate comparator with an encoder system and on-line computer service at Argonne National Laboratory. The measured lines in the spectra of 6LiD are given in this report (COO-2326-18). Similar spectra for 6LiH and 7LiH are given in companion reports (COO-2326-17) and (COO-2326-19), respectively. The relative intensities of the lines are applicable only to short regions and do not extend over the whole spectrum

  3. Indirect Study of the (2)H(d,p)(3)H and (2)H(d,n)(3)He Reactions at Astrophysical Energies via the Trojan Horse Method

    Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A.; Typel, S.; Aliotta, M.; Burjan, Václav; Del Santo, M. G.; Kiss, G.G.; Kroha, Václav; Hons, Zdeněk; La Cognata, M.; Lamia, L.; Mrázek, Jaromír; Pizzone, R. G.; Piskoř, Štěpán; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Sparta, R.

    2011-01-01

    Roč. 50, 1-4 (2011), s. 323-325. ISSN 0177-7963. [21st European Conference on Few-Body Problems in Physics Location. Salamanca, 30.08.2010-03092010] R&D Projects: GA ČR GAP203/10/0310 Institutional research plan: CEZ:AV0Z10480505 Keywords : CROSS-SECTIONS * REACTION-RATES * COMPILATION * D+D Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.438, year: 2011

  4. 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.

  5. 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).

  6. 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.)

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.).

  14. 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

  15. 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)

  16. 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.

  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 16-ch module for thermal neutron detection using ZnS:${}^6$LiF scintillator with embedded WLS fibers coupled to SiPMs and its dedicated readout electronics

    Mosset, J -B; Greuter, U; Gromov, A; Hildebrandt, M; Panzner, T; Schlumpf, N

    2016-01-01

    A scalable 16-ch thermal neutron detection system has been developed in the framework of the upgrade of a neutron diffractometer. The detector is based on ZnS:${}^6$LiF scintillator with embedded WLS fibers which are read out with SiPMs. In this paper, we present the 16-ch module, the dedicated readout electronics, a direct comparison between the performance of the diffractometer obtained with the current ${}^3$He detector and with the 16-ch detection module, and the channel-to-channel uniformity.

  19. Global optical model potentials for symmetrical lithium systems: 6Li+6Li, 7Li+7Li at Elab = 5-40 MeV

    Angular distributions of 6Li+6Li elastic scattering were measured for Elab=5-40 MeV. An optical model analysis of these data together with older data of 7Li+7Li elastic scattering taken at Elab = 8-17 MeV was performed with the aim to search for a ''global'' OM potential which describes elastic scattering in both Li-Li systems in a broad energy range. Both surface and volume absorbing potentials can be found which fulfill this requirement if a linear energy dependence is assumed of the depths of the real as well as the imaginary potential. These depths, if fitted to individual angular distributions, are found to vary in a correlated manner with the beam energy. This is taken as indication of strong coupling between elastic, inelastic, and reaction channels. This is corroborated by the existence of resonances in reaction channels at these energies where the potential depths are most pronouncedly changing. (orig.)

  20. Electroexcitation of 6Li with application to the reactions 6Li(π-,γ)/sub 1s/ 6He(0+,2+)

    The transverse form factor for the 5.37 MeV(2+,T=1) level of 6Li is analyzed in terms of a phenomenological model to give the configuration amplitudes and transition density. Radiative pion capture rates for the 1s atomic orbital of 6Li leading to the two lowest states of 6He are estimated using the phenomenological functions. The radiative pion capture rate to 6He(g.s.) agrees with experiment, but the rate to 6He(2+,1.8 MeV) is larger than the measured value. It is shown that if the longitudinal form factor is small at q approx. = m/sub π/, the transverse 5.37 MeV form factor gives the radiative pion capture matrix elements directly. As part of this study, the C2 form factor was measured near q=m/sub π/, and its implications on the wave functions are considered

  1. 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.

  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. 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.

  4. 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)

  5. 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

  6. 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)

  7. 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.

  8. Determining the 6Li Doped Side of a Glass Scintillator for Ultra Cold Neutrons

    Jamieson, Blair

    2015-01-01

    Ultracold neutron (UCN) detectors using two visually very similar, to the microscopic level, pieces of optically contacted Cerium doped lithium glasses have been proposed for high rate UCN experiments. The chief difference between the two glass scintillators is that one side is 6Li depleted and the other side Li doped. This note outlines a method to determine which side of the glass stack is doped with 6Li using AmBe and 252Cf neutron sources, and a Si surface barrier detector. The method sees an excess of events around the alpha and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.

  9. Effect of nucleon momentum inside cluster nuclei 6Li and 6He

    6Li and 6He are cluster nuclei including a tightly bound alpha (4He) core surrounded by two loosely bound nucleons. The One-Nucleon Exchange (ONE) process in p(6He, 4He+n)d and p(6Li, 4He+p)d reactions has been measured for the first time in inverse kinematics to study nucleon-nucleon correlations at rather short range of two nucleon system in 6He and 6Li. In frame of this work we are concentrated in analyzing the effect of Fermi nucleon momentum inside two these nuclei on kinematics of the ONE reaction mentioned above via calculation and measurement for angular distribution of the emitted alpha particles with respect to the beam direction. (author)

  10. Study of direct and sequential break-up reactions in 6Li+ 112Sn system

    The 6Li projectile while moving in the field of a target nucleus can not only dissociate into α+d but it can also first exchange a few nucleon with the target and then break up into two fragments. Identification of all these processes is important to understand the break-up mechanism of 6Li projectile and also to find the origin of the high yield of alpha particle production in such a reaction. In this paper, we present the exclusive measurement of breakup cross sections in 6Li+112Sn reaction exploring the above possibilities. Cross sections for both sequential as well as direct breakup are measured and compared with the theoretical calculations. The measured elastic scattering angular distributions were used as a constraint to the potential parameters that were used in the calculations to explain both elastic scattering and the breakup processes simultaneously

  11. (6)Li, (7)Li Nuclear Magnetic Resonance Investigation of Lithium Coordination in Binary Phosphate Glasses

    Alam, T.M.; Boyle, T.J.; Brow, R.K.; Conzone, S.

    1999-02-08

    {sup 6}Li and {sup 7}Li solid state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy has been used to investigate the local coordination environment of lithium in a series of xLi{sub 2}O {center_dot} (1-x)P{sub 2}O{sub 5} glasses, where 0.05 {le} x {le} 0.55. Both the {sup 6}Li and {sup 7}Li show chemical shift variations with changes in the Li{sub 2}O concentration, but the observed {sup 6}Li NMR chemical shifts closely approximate the true isotropic chemical shift and can provide a measure of the lithium bonding environment. The {sup 6}Li NMR results indicate that in this series of lithium phosphate glasses the Li atoms have an average coordination between four and five. The results for the metaphosphate glass agree with the coordination number and range of chemical shifts observed for crystalline LiPO{sub 3}. An increase in the {sup 6}Li NMR chemical shift with increasing Li{sub 2}O content was observed for the entire concentration range investigated, correlating with increased cross-linking of the phosphate tetrahedral network by O-Li-O bridges. The {sup 6}Li chemical shifts were also observed to vary monotonically through the anomalous glass transition temperature (T{sub g}) minimum. This continuous chemical shift variation shows that abrupt changes in the Li coordination environment do not occur as the Li{sub 2}O concentration is increased, and such abrupt changes can not be used to explain the T{sub g} minimum.

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

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

    2012-11-12

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

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

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

    2016-03-01

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

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

    Maris P.

    2016-01-01

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

  15. The In Situ Polymerization and Characterization of PA6/LiCl Composites

    Dandan Sun

    2013-01-01

    Full Text Available PA6/LiCl composites were synthesized by in situ anionic polymerization based on the interaction between the inorganic salts and PA6. Sodium hydroxide as initiator and N-acetylcaprolactam as activator were used in the preparation of PA6/LiCl composites with variety of LiCl content. X-ray diffraction (XRD and differential scanning calorimeter (DSC testing results showed that both of degree of crystallinity and melting temperature of the composites were decreased under the influence of LiCl. And the γ crystal phase proportion increased with increasing the LiCl content to appropriate amount.

  16. 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)

  17. 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

  18. Role of projectile breakup in {sup 6}He and {sup 6}Li induced fusion reactions around barrier energies

    Kumari, Anju; Kharab, Rajesh, E-mail: kharabrajesh@rediffmail.com

    2015-09-15

    The influence of projectile breakup on fusion cross section for {sup 6}He + {sup 209}Bi, {sup 6}He + {sup 64}Zn, {sup 6}Li + {sup 209}Bi and {sup 6}Li + {sup 64}Zn reactions at near barrier energies is studied within the framework of quantum diffusion approach. The breakup does not affect the fusion induced by {sup 6}He, whereas a significant suppression for {sup 6}Li induced reaction is observed in below barrier energy region.

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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-

  4. 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.

  5. Requirements for charged-particle reaction cross sections in the d-d, d-t, t-t, and d-3He fuel cycles

    This paper reviews the status of experimental data and data evaluations for charged-particle reactions of interest in fusion-reactor design. In particular, the 2H(t,α)n, 2H(d,p)3H, 2H(d,3He)n, 3H(t,α)nn and 3He(d,p)4He reactions at low energies are studied. Other secondary reactions are considered. The conclusion is that such cross sections are well known for the near and medium term, and that no crucial experimental lack exists. There is a serious lack of standard evaluations of these reactions, which should be in an internationally acceptable format and easily accessible. Support for generating such evaluations should be given serious consideration

  6. 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)

  7. 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)

  8. Basic technology for {sup 6}Li enrichment using an ionic-liquid impregnated organic membrane

    Hoshino, Tsuyoshi, E-mail: hoshino.tsuyoshi@jaea.go.jp [Blanket Irradiation and Analysis Group, Fusion Research and Development Directorate, Japan Atomic Energy Agency, 4002, Narita-cho, Oarai-machi, Higashi Ibaraki-gun, Ibaraki 311-1393 (Japan); Terai, Takayuki [The Institute of Engineering Innovation and Department of Nuclear Engineering and Management School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2011-10-01

    The tritium needed as a fuel for fusion reactors is produced by the neutron capture reaction of lithium-6 ({sup 6}Li) in tritium breeding materials. However, natural Li contains only about 7.6 at.% {sup 6}Li. In this paper, a new lithium isotope separation technique using an ionic-liquid impregnated organic membrane is proposed. In order to separate and concentrate lithium isotopes, only lithium ions are able to move through the membrane by electrodialysis between the cathode and the anode in lithium solutions. Preliminary experiments of lithium isotope separation were conducted using this phenomenon. Organic membranes impregnated with TMPA-TFSI and PP13-TFSI as ionic liquids were prepared, and the relationship between the {sup 6}Li separation coefficient and the applied electrodialytic conditions was evaluated using them. The results showed that the {sup 6}Li isotope separation coefficient in this method (about 1.1-1.4) was larger than that in the mercury amalgam method (about 1.06).

  9. Optical model studies of 6Li elastic scattering at 156 MeV

    Differential cross sections for 6Li elastic scattering at 156 MeV from 12C, 40Ca 90Zr and 208Pb are presented. The sensitivity to various potential forms is established by using Saxon Woods, Saxon-Woods-squred, density independent and density dependent folded potentials. The extent to which the experimental data determine the potentials and related quantities is discussed. (orig.)

  10. 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

  11. Nuclear reactions of the system {sup 6} Li on {sup 58} Ni near the Coulomb barrier; Reacciones nucleares del sistema {sup 6} Li sobre {sup 58} Ni cerca de la barrera de Coulomb

    Lizcano, D.; Aguilera, E.F.; Garcia M, H.; Martinez Q, E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    Protons, alpha particles and deuterons coming from the reactions {sup 6} Li + {sup 58} Ni are detected to three different energy around the Coulomb barrier. The possible effects of the weakly bound character of the projectile are studied and the results are compared with previous data for the system {sup 6} Li + {sup 59} Co. (Author)

  12. 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

  13. 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

  14. Gamow shell model description of radiative capture reactions $^6$Li$(p,\\gamma)$$^7$Be and $^6$Li$(n,\\gamma)$$^7$Li

    Dong, G X; Fossez, K; Płoszajczak, M; Jaganathen, Y; Betan, R M Id

    2016-01-01

    According to standard stellar evolution, lithium abundance is believed to be a useful indicator of the stellar age. However, many evolved stars like red giants show huge fluctuations around expected theoretical abundances that are not yet fully understood. The better knowledge of nuclear reactions that contribute to the creation and destruction of lithium can help to solve this puzzle. In this work we apply the Gamow shell model (GSM) formulated in the coupled-channel representation (GSM-CC) to investigate the mirror radiative capture reactions $^6$Li$(p,\\gamma)$$^7$Be and $^6$Li$(n,\\gamma)$$^7$Li. The cross-sections are calculated using a translationally invariant Hamiltonian with the finite-range interaction which is adjusted to reproduce spectra, binding energies and one-nucleon separation energies in $^{6-7}$Li, $^7$Be. All relevant $E1$, $M1$, and $E2$ transitions from the initial continuum states to the final bound states $J={3/2}_1^-$ and $J={1/2}^-$ of $^7$Li and $^7$Be are included. We demonstrate th...

  15. Production of antimatter 5,6Li nuclei in central Au+Au collisions at sNN=200 GeV

    Kai-Jia Sun

    2015-12-01

    Full Text Available Combining the covariant coalescence model and a blast-wave-like analytical parametrization for (anti-nucleon phase–space freezeout configuration, we explore light (anti-nucleus production in central Au+Au collisions at sNN=200 GeV. Using the nucleon freezeout configuration (denoted by FO1 determined from the measured spectra of protons (p, deutrons (d and 3He, we find the predicted yield of 4He is significantly smaller than the experimental data. We show this disagreement can be removed by using a nucleon freezeout configuration (denoted by FO2 in which the nucleons are assumed to freeze out earlier than those in FO1 to effectively consider the effect of large binding energy value of 4He. Assuming the binding energy effect also exists for the production of 5Li, Li‾5, 6Li and Li‾6 due to their similar binding energy values as 4He, we find the yields of these heavier (anti-nuclei can be enhanced by a factor of about one order, implying that although the stable (anti-6Li nucleus is unlikely to be observed, the unstable (anti-5Li nucleus could be produced in observable abundance in Au+Au collisions at sNN=200 GeV where it may be identified through the p–4He (p‾–He‾4 invariant mass spectrum. The future experimental measurement on (anti-5Li would be very useful to understand the production mechanism of heavier antimatter.

  16. Measurement of the 1H(6He,6Li)n reaction in inverse kinematics

    The 1H(6He,6Li)n reaction was studied at 0 degree with the NSCL A1200 fragment separator in the energy loss mode. A 6He secondary beam at E/A=93 MeV was used to measure the Gamow-Teller and Fermi strengths between the ground state of 6He and the ground and excited states of 6Li, in inverse kinematics. At 0 degree the ground-state cross section is measured to be dσGS/(dΩ)=43±16 mb/sr, which is dominated by systematic error in the secondary beam flux. The ratio of Gamow-Teller to Fermi strength is not sensitive to this error and is found to be (87±6)% of that expected from (p,n) systematics and β decay. Angular distributions have been measured between 0 degree and 10 degree in the center of mass. copyright 1996 The American Physical Society

  17. Effect of target deformation and projectile breakup in complete fusion of 6Li + 152Sm

    Nuclear reaction induced by weakly bound (stable or radioactive) nuclei is a subject of current experimental and theoretical interest. Measurements of fusion cross section involving loosely bound projectile 6Li and 9Be exist with different conclusion about the enhancement or suppression of fusion cross section. Recently we have measured the fusion cross section for 6Li + 144Sm, where it has been found that there is an enhancement of fusion cross section below the barrier in comparison with single BPM calculation, where as there is an overall suppression in fusion cross section as compared to CCFULL calculation in the entire energy range measured. With this motivation, we chose a deformed target, 152Sm, with β2 = 0.24 to compare with the results of 144Sm which is a spherical target. It will also be interesting to see effect of target deformation (enhancement) versus projectile breakup (suppression) specially at subbarrier energy

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

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

    2016-03-01

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

  19. Neutron assay in mixed radiation fields with a 6Li-loaded plastic scintillator

    A novel technique for assay of thermal and fast neutrons in a 6Li-loaded plastic scintillator is presented. Existing capture-gated thermal neutron detection techniques were evaluated with the 6Li-loaded plastic scintillator studied in this work. Using simulations and experimental work, shortcomings in its performance were highlighted. As a result, it was proposed that by separating the combined fast and thermal neutron events from gamma events, using established pulse shape discrimination techniques, the thermal neutron events could then be assayed. Experiments were conducted at the National Physical Laboratory, Teddington, performing neutron assays with seven different neutron fields using the proposed technique. For each field, thermal and fast neutron content was estimated and were shown to corroborate with the seven synthesised fields

  20. Electron-scattering form factors for 6Li in the ab initio symmetry-guided framework

    Dytrych, T; Launey, K D; Draayer, J P; Maris, P; Vary, J P; Langr, D; Oberhuber, T

    2015-01-01

    We present an ab initio symmetry-adapted no-core shell-model description for $^{6}$Li. We study the structure of the ground state of $^{6}$Li and the impact of the symmetry-guided space selection on the charge density components for this state in momentum space, including the effect of higher shells. We accomplish this by investigating the electron scattering charge form factor for momentum transfers up to $q \\sim 4$ fm$^{-1}$. We demonstrate that this symmetry-adapted framework can achieve significantly reduced dimensions for equivalent large shell-model spaces while retaining the accuracy of the form factor for any momentum transfer. These new results confirm the previous outcomes for selected spectroscopy observables in light nuclei, such as binding energies, excitation energies, electromagnetic moments, E2 and M1 reduced transition probabilities, as well as point-nucleon matter rms radii.

  1. The 6Li(γ,p) reaction at intermediate photon energies

    The 6Li(γ,p) reaction was measured at average tagged photon energies of left angle Eγ right angle =59 and 75 MeV. Protons were detected at 5 different angles between 30 circle and 150 circle. Most of the observed strength is apparently due to the three-body breakup channels. In particular the semi-inclusive (γ,p(n)) and (γ,p(t)) channels are discussed. ((orig.))

  2. Fusion and nonfusion phenomena in the 6Li+40Ca reaction at 156 MeV

    Reaction products from 6Li-induced reactions on 40Ca at 156 MeV have been studied using the dE x E identification as well as the inclusive γ-ray method. The complete fusion cross-section has been found to be σsub(f)=(77 +- 11)mb. The Z distribution of fusion evaporation residues is compared with statistical model predictions. The Z spectrum of reaction products shows a maximum at 156Li break-up. (author)

  3. Investigation of the selection of the selectively heated ions of 6Li isotope from lithium plasma

    Results of experiments on preparation of enriched lithium by means of plasma isotope separation method using ion cyclotron resonance (ICR) are presented. Two types of collectors were compared: cylindrical and plane ones. Both collectors were placed just as in homogeneous magnetic field immediately after the zone of selective ICR heating, so in diverging weakened one, closer to solenoid end. In cylindrical collector higher lithium enrichment by 6Li (up to 83 %) is observed. That corresponds to distribution coefficient ≅60

  4. Formation of eta'(958) Meson Bound States by the 6Li(gamma,d) reaction

    Miyatani, M; Nagahiro, H; Hirenzaki, S

    2016-01-01

    We have investigated the 6Li(gamma,d) reaction theoretically for the formation of the eta'(958) mesic nucleus close to the recoilless kinematics. We have developed the theoretical formula and reported the quantitative results of the formation spectra for various cases in this article. We have found that the formation cross sections are reduced by the effects of the fragile deuteron form factor.

  5. BEC of 41 K in a Fermi sea of 6 Li

    Lous, Rianne S.; Fritsche, Isabella; Huang, Bo; Jag, Michael; Cetina, Marko; Walraven, Jook T. M.; Grimm, Rudolf

    2016-05-01

    We report on the production of a 41 K Bose-Einstein condensate (BEC) immersed in a degenerate two-component 6 Li Fermi sea. After evaporation in an optical dipole trap, we obtain 1 . 2 ×104 41 K atoms with a 55% BEC fraction and a Fermi sea with T /TF work is supported by the Austrian Science Fund FWF within the collaborative research grant FoQuS.

  6. Measurement of interaction energy near a Feshbach resonance in a 6Li Fermi gas

    Bourdel, T; Cubizolles, J.; Khaykovich, L.; Magalhaes, K. M. F.; Kokkelmans, S. J. J. M. F.; G. V. Shlyapnikov; Salomon, C

    2003-01-01

    We investigate the strongly interacting regime in an optically trapped $^6$Li Fermi mixture near a Feshbach resonance. The resonance is found at $800(40) $G in good agreement with theory. Anisotropic expansion of the gas is interpreted by collisional hydrodynamics. We observe an unexpected and large shift ($80 $G) between the resonance peak and both the maximum of atom loss and the change of sign of the interaction energy.

  7. Development of a mini high efficiency neutron detector based on 6LiI (Eu) scintillator

    A mini neutron detector with the dimension of φ25 mm ×20 mm is developed based on a 6LiI( Eu) scintillator with a Hamamatsu S3590-08 photodiode. The detector was used to detect thermal neutrons from a paraffin shielded 252Cf neutron source and the detect efficiency to thermal neutron was calculated to be 95% with a resolution of thermal neutron peak about 16%. (authors)

  8. Understanding the effect of channel coupling on fusion of 6Li+64Ni

    Moin Shaikh, Md.; Roy, Subinit

    2016-07-01

    The effect of inelastic excitation and single particle transfer reactions on fusion have been investigated for the system 6Li+64Ni at near barrier energies. The calculations show that a simultaneous coupling to the inelastic excitation of projectile and target along with positive Q-value 1n- and 1p-stripping channels, describes the experimental CF cross sections reasonably well in the below barrier region.

  9. 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

  10. 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.

  11. 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.

  12. THE NEW DETECTIONS OF 7Li/6Li ISOTOPIC RATIO IN THE INTERSTELLAR MEDIA

    We have determined the isotopic abundance ratio of 7Li/6Li in the interstellar media (ISMs) along lines of sight to HD169454 and HD250290 using the High-Dispersion Spectrograph on the Subaru Telescope. We also observed ζ Oph for comparison with previous data. The observed abundance ratios were 7Li/6Li = 8.1+3.6-1.8 and 6.3+3.0-1.7 for HD169454 and HD250290, respectively. These values are in reasonable agreement with those observed previously in the solar neighborhood ISMs within ±2σ error bars and are also consistent with our measurement of 7Li/6Li = 7.1+2.9-1.6 for a cloud along the line of sight to ζ Oph. This is good evidence for homogeneous mixing and instantaneous recycling of the gas component in the Galactic disk. We also discuss several source compositions of 7Li, Galactic cosmic-ray interactions, stellar nucleosynthesis, and big bang nucleosynthesis.

  13. 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.

  14. 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.).

  15. 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...

  16. 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.

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. 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)

  2. Elastic break-up of 156 MeV 6Li projectiles with large asymptotic relative momenta of the fragments

    The triple differential cross sections for elastic break-up of 156 MeV 6Li projectiles by the reactions 208Pb (6Li, ad) 208Pbg.s., and 12C (6Li, ad) 12Cg.s. have been measured with large asymptotic relative momenta of the outgoing fragments. The data exhibit rather unfamiliar shapes of the energy spectra, often replacing the usual bell-shape distributions by double-peaked structures and varying rapidly with the relative emission angles. The origin of these features has been explored and the cross sections have been analysed on the basis of a diffractive disintegration approach. (orig.)

  3. Standard model contribution to the electric dipole moment of the deuteron, 3H, and 3He nuclei

    Yamanaka, Nodoka; Hiyama, Emiko

    2016-02-01

    We calculate for the first time the electric dipole moment (EDM) of the deuteron, 3H, and 3He nuclei generated by the one-meson exchange CP-odd nuclear force in the standard model. The effective |Δ S| = 1 four-quark operators are matched to the |Δ S| = 1 standard model processes involving the CP phase of the Cabibbo-Kobayashi-Maskawa matrix at the electroweak scale and run down to the hadronic scale μ = 1 GeV according to the renormalization group evolution in the next-to-leading logarithmic order. At the hadronic scale, the hadron matrix elements are modeled in the factorization approach. We then obtain the one-meson (pion, eta meson, and kaon) exchange CP-odd nuclear force, which is the combination of the |Δ S| = 1 meson-baryon vertices which issue from the penguin operator and the hyperon-nucleon transition. From this CP-odd nuclear force, the nuclear EDM is calculated with the realistic Argonne v18 interaction and the CP-odd nuclear force using the Gaussian expansion method. It is found that the EDMs of light nuclear systems are of order O (10-31) e cm. We also estimate the standard model contribution to other hadronic CP violating observables such as the EDMs of 6Li, 9Be nuclei, and the atomic EDMs of 129Xe, 199Hg, 211Rn, and 225Ra generated through the nuclear Schiff moment. We then analyze the source of theoretical uncertainties and show some possible ways to overcome them.

  4. Triple-differential cross section of the 208Pb(6Li, αd)208 Pb Coulomb breakup and astrophysical S-factor of the d(α,γ)6 Li reaction at extremely low energies

    A method of calculation of the triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup at astrophysically relevant energies E of the relative motion of the breakup fragments, taking into account the three-body (α - d - 208Pb) Coulomb effects and the contributions from the E1- and E2- multipoles, including their interference, has been proposed. The new results for the astrophysical S-factor of the direct radiative capture d(α, γ)6 Li reaction at E ≤ 250 keV have been obtained. It is shown that the experimental triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup can also be used to give information about the value of the modulus squared of the nuclear vertex constant for the virtual 6Li → α + d. (author)

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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...

  11. 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].

  12. 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.

  13. 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

  14. 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.

  15. 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.)

  16. 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.

  17. 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.

  18. 16O resonances near 4α threshold through 12C(6Li,d) reaction

    Several narrow alpha resonant 16O states were detected through the 12C(6Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)

  19. Comparative analysis of pulse shape discrimination methods in a 6Li loaded plastic scintillator

    Three algorithms for discriminating between fast neutrons, thermal neutrons and gamma rays in a 6Li loaded plastic scintillator have been compared. Following a literature review of existing pulse shape discrimination techniques, the performance of the charge comparison method, triangular filtering and frequency gradient analysis were investigated in this work. The scintillator was exposed to three different mixed gamma/neutron radiation fields. The figure of merit of neutron/gamma separation was investigated over a broad energy range, as well as for the neutron capture energy region. After optimisation, all three methods were found to perform similarly in terms of neutron/gamma separation

  20. Model Calculation of n + 6Li Reactions Below 20 MeV

    ZHANG Jing-Shang; HAN Yin-Lu

    2001-01-01

    Based on the unified Hauser-Feshbach and exciton model for light nuclei, the calculations of reaction cross sections and the double-differential cross sections for n + 6Li are performed. Since all of the first-particle emissions are from the compound nucleus to the discrete levels, the angular momentum coupling effect in pre-equilibrium mechanism must be taken into account. The fitting of the measured data indicates that the three-body break-up process needs to be involved, and the pre-equilibrium reaction mechanism dominates the reaction processes. In light nucleus reactions the recoil effect must be taken into account.``

  1. The scattering of 136 MeV protons from 6Li

    Differential cross sections have been measured for the elastic scattering of 136 MeV protons from 6Li, and for inelastic scattering to the first two excited states. The optical model fit to the elastic scattering differential cross section gave parameters which were retained for the analysis of the two inelastic transitions. The latter differential cross sections were fairly well fitted in shape, but in both cases there is a discrepancy in absolute magnitude of a factor between 1.5 and 4

  2. Elastic scattering for the system {sup 6}Li+p at near barrier energies with MAGNEX

    Soukeras, V.; Pakou, A.; Sgouros, O. [Department of Physics and HINP, The University of Ioannina, 45110 Ioannina (Greece); Cappuzzello, F.; Bondi, M.; Nicolosi, D. [INFN Laboratory Nazionali del Sud, via S. Sofia 62, 95125, Catania, Italy and Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, 95125, Catania (Italy); Acosta, L.; Marquinez-Duran, G.; Martel, I. [Departamento di Fisica Aplicada, Universidad de Huelva, E-21071, Huelva (Spain); Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; Di Pietro, A.; Fernández-García, J. P.; Figuera, P.; Fisichella, M. [INFN Laboratory Nazionali del Sud, via S. Sofia 62, 95125, Catania (Italy); Alamanos, N. [CEA-Saclay, DAPNIA-SPhN, 91191, Gif-sur-Yvette (France); De Napoli, M. [INFN - Sezione di Catania, via S. Sofia 64, 95125, Catania (Italy); Foti, A. [Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, 95125, Catania, Italy and INFN - Sezione di Catania, via S. Sofia 64, 95125, Catania (Italy); and others

    2015-02-24

    Elastic scattering measurements have been performed for the {sup 6}Li+p system in inverse kinematics at the energies of 16, 20, 25 and 29 MeV. The heavy ejectile was detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS) in Catania, in the angular range between ∼2{sup 0} and 12{sup 0} in the laboratory system, giving us the possibility to span almost a full angular range in the center of mass system. Results will be presented and discussed for one of the energies.

  3. Nuclear Reaction 6Li(n,4He)T as Radiation Source

    Our investigation was based on the reaction 6Li(n,4He)T, most convenient for the generation of high intensity flow of tritons by the use of thermal neutron flux in atomic reactor. This reaction has high cross section (sigma=953 b), practically no threshold, is rather exothermic (Q=4.78 MeV) and kinetic energy of charged particles (Et=2,74 MeV) is sufficient for the penetration through potential barrier of light elements with Z11C, 13N, 18F, 28Mg, 34mCI and more long lived 3H for medical purposes

  4. Tritium production in a sphere of 6LiD irradiated by 14-MeV neutrons

    The specific production of tritium in samples of 6LiH and 7LiH embedded in a 600-mm-diam sphere of 6LiD irradiated by a central source of 14-MeV neutrons was determined by measuring the activity of the hydrogen evolved from the samples of each isotope at each of five different radii in the 6LiD assembly. The entire process of decomposing the LiH, transferring the evolved gas into counters, and determining the decay rate was standardized by processing LiH samples irradiated by thermal neutrons for which the 6Li(n,α) cross section is well known. The specific production of tritium in 6LiH and 7LiH (embedded samples) and the activation of radiochemical detector foils of 45Sc, 89Y, 90Zr, 169Tm, 191Ir 373, 193Ir 627, 197Au, 235U, and 238U placed at various positions in the 6LiD sphere were calculated and compared with the experimental data. One- and three-dimensional Monte Carlo and S/sub n/ neutron-transport calculations were performed. The most reliable (three-dimensional Monte Carlo) calculation is in reasonable agreement with both the tritium-production and the radiochemical-activation data. The existing discrepancies between calculation and experiment appear largely attributable to uncertainties in some tritium-production and radiochemical-activation cross sections. 15 references

  5. 6Li detection in metal-poor stars: can 3D model atmospheres solve the second lithium problem?

    Steffen, M; Caffau, E; Bonifacio, P; Ludwig, H -G; Spite, M

    2012-01-01

    The presence of 6Li in the atmospheres of metal-poor halo stars is usually inferred from the detection of a subtle extra depression in the red wing of the 7Li doublet line at 670.8 nm. However, the intrinsic line asymmetry caused by convective flows in the photospheres of cool stars is almost indistinguishable from the asymmetry produced by a weak 6Li blend on a (presumed) symmetric 7Li profile. Previous determinations of the 6Li/ 7Li isotopic ratio based on 1D model atmospheres, ignoring the convection-induced line asymmetry, must therefore be considered as upper limits. By comparing synthetic 1D LTE and 3D non-LTE line profiles of the Li 670.8 nm feature, we quantify the differential effect of the convective line asymmetry on the derived 6Li abundance as a function of effective temperature, gravity, and metallicity. As expected, we find that the asymmetry effect systematically reduces the resulting 6Li/7Li ratios. Depending on the stellar parameters, the 3D-1D offset in 6Li/7Li ranges between -0.005 and -0....

  6. 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.

  7. Measurement of 6Li(n,α)3H reaction cross section

    The 6Li(n,α)3H reaction cross section was measured at 12 discrete neutron energies between 80 KeV and 470 KeV by using the Oak Ridge Linear Acelerator (ORELA) as a pulsed neutron source. The neutron beam was filtered through 20 cm or 30 cm of Armco iron which produces several monoenergetic energies groups (iron windows) between 20 KeV and 1000 KeV about 2 KeV wide. The (n,α) events were detected by a 1 mm thick Li-glass scintillator and the neutron flux was measured with a NE110 plastic scintillator 6,6 cm thick and 10 cm in diameter. Multiple scattering corrections in the Li-glass and the NE110 scintillator efficiency were determined theoretically by using Monte Carlo technique. The 6Li content in the Li-glasses was determined by transmission measurements with low energy neutrons. A theoretical fit was applied to the results by the R-matrix theory. (Author)

  8. Detection efficiency simulation and measurement of 6LiI/natLiI scintillation detector

    Background: Being of very high detection efficiency and small size, Lithium iodide (LiI) scintillator detector is used extensively in neutron measurement and environmental monitoring. Purpose: Using thermal reactor, neutron detectors will be tested and calibrated. And a new neutron detector device will be designed and studied. Methods: The relationship between the size and detection efficiency of the thermal neutron detector 6LiI/natLil was studied using Monte Carlo code GEANT4 and MCNP5 package, and the thermal neutron efficiency of detector was calibrated by reactor neutrons. Results: The theoretical simulation shows that the thermal neutron detection efficiency of detector of 10-mm thickness is relatively high, the enriched 6Lil is up to 98% and the nature natLiI 65%. The thermal neutron efficiency of detector is calibrated by reactor thermal neutrons. Considering the neutron scattering by the lead brick, high density polythene and environment neutron contribution, the detection efficiency of 6LiI detector is about 90% and natLiI detector 70%. Conclusion: The detector efficiency can reach the efficiency value of theoretical calculations. (authors)

  9. Measuring the absorption mean cross section in 6Li relative to 235U fission

    Due to the fact that the neutron absorption cross section in 6Li is used as one of standards for determinaton of neutron-physical characteristics of fast reactors the ratio of mean cross sections for absorption by 6Li (A6) and 235U fission F25 are experimentalli investigated. The measurements have been performed in the KBR-8, KBR-10,BFS/39/1 bfs-44, BFS/45a-1 and BFS-46 critical assemblies which are characterized by various neutron spectra by means of a lithium counter with semiconductor detectors. Ratios A6/F25 for investigated assemblies constituted respectively 0.605+-0.009; 0.604+-0.004; 0.581+-0.009; 0.590+-0.574+-0.005. The values of 235U diffusion mean cross sections obtained on the base of these fata and calculated using the CRAB-1 program (given in brackets) are equal respectively 1.53+-0.005 (1.51) 2.38+-0.08 (2.42); 1.935+-0.060 (1.95); 1.89+-0.08 (1.95); 1.780+-0.11 (1.69); 1.90+-0.06 (1.89)

  10. Moderator type neutron spectrometer using 6LiF thermoluminescence dosimeter (TLD)

    For epithermal neutron spectroscopy, one of the important problems in neutron and health physics, a few methods have been considered, but each has difficulties, respectively. To overcome these difficulties and obtain the simple and stable detector operation, a moderator type simultaneous multi-detector has been developed, which has 15 6LiF TLD's embedded in polyethylene moderator. (It is called Filter Transmission Detector (FTD) by the author.) This gives 15 simultaneous data, different in moderating filter sensitivity. Also, the dynamic range of measurement can be large, and the perturbation in the moderator by the detectors can be made small. The paper first describes on the characteristics of 6LiF TLD, then gives the specifications of FTD and reports on the calculated results of response function. In the measurement using a 252Cf neutron source, the spatial distribution of reactivity composed from the response functions and neutron spectra comparatively well agreed with the experimental values. The results of verification in actual neutron field (after transmitted in the fast column and concrete of the reactor ''Yayoi'') showed relatively good agreement with other spectrometrical results in the energy range of tens of keV to MeV. (Wakatsuki, Y.)

  11. Alpha cluster states in light nuclei populated through the (6Li,d) reaction

    Full text: The alpha cluster correlation is an important concept in the nuclear physics of light nuclei. The main purpose of the research program in progress is the investigation of the alpha clustering phenomenon in (xα) and(xα+ν) nuclei through the (6Li,d) alpha transfer reaction. In fact, there is scarce experimental information on the subject, in particular associated with resonant states predicted near (xα) and (xα+ν) thresholds. Measurements of the 12,13C(6Li,d) 16,17O reactions, at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique. The work is under way and an experimental energy resolution of 30 keV was obtained. Near the (4α) breakup threshold in 16O, three narrow alpha resonances, not previously measured, were detected, revealing important α + 12C(G.S.) components. One of these resonances corresponds to the known 0+ state at 15.1 MeV[5] of excitation that has probably, according to Funaki et al., the gas like configuration of the 4α condensate state, with a very dilute density and a large component of α + 12C(Hoyle) configuration. As was already mentioned, our experimental information points to the necessity of including the α + 12C(G.S.) component in the wave function. (author)

  12. 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.

  13. 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...

  14. 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.

  15. 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.)

  16. 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

  17. 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

  18. 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.)

  19. 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

  20. 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.

  1. 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

  2. Nuclear reaction analysis of 1H and 2H in hafnium silicate films on Si

    The 1H(15N,αγ)12C and 2H(3He,p)4He nuclear reactions were employed to detect, respectively, 1H and 2H in hafnium silicates films on Si. The methods employed to achieve quantitative analyses are described. Moreover, by performing annealing sequences in vacuum or O2 followed by 1H2 or 2H2, it was observed that the O2-preanneled films incorporate less H, either 1H or 2H. This was explained by O-deficient, H-trapping sites that are eliminated by the O2 preannealing

  3. 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.)

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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}.

  10. 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.

  11. 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.

  12. 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)

  13. 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...

  14. 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

  15. 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...

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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

  3. 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.)

  4. 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.)

  5. Reanalysis of tritium production in a sphere of 6LiD irradiated by 14-MeV neutrons

    Tritium production and activation of radiochemical detector foils in a sphere of 6LiD irradiated by a central source of 14-MeV neutrons has been reanalyzed. The 6LiD sphere consisted of 10 solid hemispherical nested shells with ampules of 6LiH, 7LiH, and activation foils located 2.2, 5, 7.7, 12.6, 20, and 30 cm from the center. The Los Alamos Monte Carlo Neutron Photon Transport Code (MCNP) was used to calculate neutron transport through the 6LiD, tritium production in the ampules, and foil activation. The MCNP input model was three-dimensional and employed ENDF/B-V cross sections for transport, tritium production, and (where available) foil activation. The reanalyzed experimentally observed-to-calculated values of tritium production were 1.053 +- 2.1% in 6LiH and 0.999 +- 2.1% in 7LiH. The recalculated foil activation observed-to-calculated ratios were not generally improved over those reported in the original analysis

  6. MeV Neutron Production from Thermal Neutron Capture in {6}^Li Simulated with Geant4

    Santoro, Valentina; Bentley, Phillip M

    2015-01-01

    Various Li compounds are commonly used at neutron facilities as neutron absorbers. These compounds provide one of the highest ratios of neutron attenuation to $\\gamma$-ray production. Unfortunately, the usage of these compounds can also give rise to fast neutron emission with energies up to almost 16 MeV. Historically, some details in this fast neutron production mechanism can be absent from some modeling packages under some optimization scenarios. In this work, we tested Geant4 to assess the performance of this simulation toolkit for the fast neutron generation mechanism. We compare the results of simulations performed with Geant4 to available measurements. The outcome of our study shows that results of the Geant4 simulations are in good agreement with the available measurements for $^6$Li fast neutron production, and suitable for neutron instrument background evaluation at spallation neutron sources.

  7. Nuclear shell-model calculations for 6Li and 14N with different NN potentials

    Two ''phase-shift equivalent'' local NN potentials with different parametrizations, Reid93 and NijmII, which were found to give nearly identical results for the triton by Friar et al., are shown to yield remarkably similar results for 6Li and 14N in a (0+2)ℎΩ no-core space shell-model calculation. The results are compared with those for the widely used Hamada-Johnson hard-core and the original Reid soft-core potentials, which have larger deuteron D-state percentages. The strong correlation between the tensor strength and the nuclear binding energy is confirmed. However, many nuclear structure properties seem to be rather insensitive to the details of the NN potential and, therefore, cannot be used to test various NN potentials

  8. Investigation of α-cluster states in 13C via the (6Li,d) reaction

    Rodrigues, M R D; Horodynski-Matsushigue, L B; Cunsolo, A; Cappuzzello, F; Duarte, J L M; Rodrigues, C L; Ukita, G M; Souza, M A; Miyake, H

    2010-01-01

    The 9Be(6Li,d)13C reaction was used to investigate possible α-cluster states in 13C. The reaction was measured at 25.5 MeV incident energy, employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion detection technique. Ten out of sixteen known levels of 13C, up to 11 MeV of excitation, were observed and, due to the much improved energy resolution of 50 keV, at least three doublets could be resolved. This work presents a preliminary analysis of five of the most intensely populated states, also in comparison with the results of former transfer studies.

  9. Alpha Resonances in 13C Excited by the 9Be (6Li,d) Reaction

    The 9Be(6Li,d)13C reaction was used to investigate alpha resonant states in 13C up to 13 MeV of excitation. The reaction was measured at a bombarding energy of 25.5 MeV employing the Sao Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion detection technique. The resolution of 50 keV allowed for the separation of the resonant contributions to the known 7/2- at 10.753 MeV and (5/2-) at 10.818 MeV 13C states. The alpha resonance seen at the (3α+n) threshold was not previously reported. The experimental angular distributions are presented in comparison with DWBA predictions.

  10. Resonances excited by the 9Be(6Li,d)13C reaction

    Alpha resonant states in 13C up to 15 MeV were excited by the 9Be(6Li,d)13C reaction. The data were taken at a bombarding energy of 25.5 MeV employing the Sao Paulo-Pelletron-Enge Split Pole facility and the nuclear emulsion technique. The resolution of 50 keV allowed for the separation of the resonant contributions to the known 7/2- and (5/2-) states near the 9Be + α threshold both associated with an L = 4 transfer. Several narrow alpha resonant states not previously measured were detected, in particular the one at the 3α + n threshold populated by an L = 2 transfer, revealing a 9Be + α component for the 1/2- cluster state candidate at this threshold. (author)

  11. Thermal neutron detection by entrapping 6LiF nanocrystals in siloxane scintillators

    Carturan, S. M.; Marchi, T.; Maggioni, G.; Gramegna, F.; Degerlier, M.; Cinausero, M.; Dalla Palma, M.; Quaranta, A.

    2015-06-01

    Exploiting the long experience in design and production of scintillating mixtures based on siloxane matrices with combinations of primary dye and waveshifter, a first set of 6LiF loaded scintillator disks has been produced. The synthesis is herein described and reported, as well as preliminary results on their light response towards thermal neutrons. The preservation of transparency and mechanical integrity of the scintillator material is challenging when introducing the inorganic salt LiF which is a "foreign body" to the organic polysiloxane host matrix Different strategies such as synthesis of nanoparticles and surface functionalization have been pursued to succeed in the entrapment of the neutron converter whilst maintaining moderate light output, optical transparency and flexibility of the base scintillator.

  12. Study of reaction products of d + 6Li at 0,18 MeV

    The study of continuous spectra of low energy particles, and more particularly of their shape and intensity allows a better understanding and knowledge of the structure of nuclei as they interact when encountering. As previous studies performed in Saclay had been interpreted by introducing the new notions of nuclear molecule or activated complex followed by a dissymmetric breaking, and in order to better understand the formation of these molecules, this research thesis reports the study of the d + 6Li reaction at 0,18 MeV. After a description of the experimental installation and of the processing of nuclear emulsions, the author presents and discusses the obtained results and calculations resulting from the fact that the different particles cannot be discriminated in the continuum. Theoretical results for the continuous spectrum are compared with experimental results, and the author reports angular distributions of alpha particles and p0 and p1 protons

  13. 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

  14. Asymptotic and near-target direct breakup of 6Li and 7Li

    Kalkal, Sunil; Simpson, E. C.; Luong, D. H.; Cook, K. J.; Dasgupta, M.; Hinde, D. J.; Carter, I. P.; Jeung, D. Y.; Mohanto, G.; Palshetkar, C. S.; Prasad, E.; Rafferty, D. C.; Simenel, C.; Vo-Phuoc, K.; Williams, E.; Gasques, L. R.; Gomes, P. R. S.; Linares, R.

    2016-04-01

    Background: Li,76 and 9Be are weakly bound against breakup into their cluster constituents. Breakup location is important for determining the role of breakup in above-barrier complete fusion suppression. Recent works have pointed out that experimental observables can be used to separate near-target and asymptotic breakup. Purpose: Our purpose is to distinguish near-target and asymptotic direct breakup of Li,76 in reactions with nuclei in different mass regions. Method: Charged particle coincidence measurements are carried out with pulsed Li,76 beams on 58Ni and 64Zn targets at sub-barrier energies and compared with previous measurements using 208Pb and 209Bi targets. A detector array providing a large angular coverage is used, along with time-of-flight information to give definitive particle identification of the direct breakup fragments. Results: In interactions of 6Li with 58Ni and 64Zn, direct breakup occurs only asymptotically far away from the target. However, in interactions with 208Pb and 209Bi, near-target breakup occurs in addition to asymptotic breakup. Direct breakup of 7Li into α -t is not observed in interactions with 58Ni and 64Zn. However, near-target dominated direct breakup was observed in measurements with 208Pb and 209Bi. A modified version of the Monte Carlo classical trajectory model code platypus, which explicitly takes into account lifetimes associated with unbound states, is used to simulate sub-barrier breakup reactions. Conclusions: Near-target breakup in interactions with Li,76 is an important mechanism only for the heavy targets 208Pb and 209Bi. There is insignificant near-target direct breakup of 6Li and no direct breakup of 7Li in reactions with 58Ni and 64Zn. Therefore, direct breakup is unlikely to suppress the above-barrier fusion cross section in reactions of Li,76 with 58Ni and 64Zn nuclei.

  15. Fast neutron measurements with 7Li and 6Li enriched CLYC scintillators

    Giaz, A.; Blasi, N.; Boiano, C.; Brambilla, S.; Camera, F.; Cattadori, C.; Ceruti, S.; Gramegna, F.; Marchi, T.; Mattei, I.; Mentana, A.; Million, B.; Pellegri, L.; Rebai, M.; Riboldi, S.; Salamida, F.; Tardocchi, M.

    2016-07-01

    The recently developed Cs2LiYCl6:Ce (CLYC) crystals are interesting scintillation detectors not only for their gamma energy resolution (neutrons. The thermal neutrons were detected by the 6Li(n,α)t reaction while for the fast neutrons the 35Cl(n,p)35S and 35Cl(n,α)32P neutron-capture reactions were exploited. The energy of the outgoing proton or α particle scales linearly with the incident neutron energy. The kinetic energy of the fast neutrons can be measured using both the Time Of Flight (TOF) technique and using the CLYC energy signal. In this work, the response to monochromatic fast neutrons (1.9-3.8 MeV) of two CLYC 1″×1″ crystals was measured using both the TOF and the energy signal. The observables were combined to identify fast neutrons, to subtract the thermal neutron background and to identify different fast neutron-capture reactions on 35Cl, in other words to understand if the detected particle is an α or a proton. We performed a dedicated measurement at the CN accelerator facility of the INFN Legnaro National Laboratories (Italy), where the fast neutrons were produced by impinging a proton beam (4.5, 5.0 and 5.5 MeV) on a 7LiF target. We tested a CLYC detector 6Li-enriched at about 95%, which is ideal for thermal neutron measurements, in parallel with another CLYC detector 7Li-enriched at more than 99%, which is suitable for fast neutron measurements.

  16. Portable gamma and thermal neutron probe using a {sup 6}LiI(Eu) crystal

    Carneiro, Clemente J.G.; Araujo, Geraldo P.; Milian, Felix M.; Barbosa, Jurandir C.; Garcia, Fermin [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil). Centro de Pesquisas em Ciencias e Tecnologias das Radiacoes (CPqCTR); Oliveira, Arno H.; Silva, Mario R.S.; Penna, Rodrigo [Universidade Federal de Minas Gerais (DEN-UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Nuclear

    2011-07-01

    Europium-activated lithium-6 iodide is a scintillator used for gamma and neutron counting. A portable detection system was built based on this scintillator. This system has three modules: the scintillator, a 10 m liquid light guide, and a Hamamatsu photon counting head H9319 used as a light pulse digitizer. Data transfer, measurement time and other necessary adjustment can be controlled by software from the PC through the RS-232C interface. The scintillator, a crystal of {sup 6}LiI(Eu), is a small cylinder with 3 mm diameter and 40 mm length completely sealed in an aluminum tube coupled to the light guide. The small size of the scintillator increases the neutron/gamma count ratio, since 2 to 3 mm of thickness of this crystal absorbs all thermal neutrons. Intensities of X and gamma rays, and thermal neutrons can be recorded for time intervals of 10 ms to 1 s storing up to 10000 countings. The system was calibrated for measuring radiation doses for validating numerical models in dosimetry. Two characteristic reinforce this application, measurements can be done at several meters away from the radiation source and also inside of water. In addition, it was used to build nuclear probes based on Compton scattering or neutron moderation in porous media by attaching an AmBe source to the top of the aluminum tube. Tests were done to determine the reproducibility of counting rates. Background counting was measured at several temperatures to verify the influence of dark current of PMT. Sealed AmBe, low activity Am, and X rays sources were used for studies of radiation counting statistics. X rays apparatus was used to correlate counting rates measured with the {sup 6}LiI(Eu) detection system and doses measured with an ionization chamber at several distances from the X ray source. (author)

  17. Alpha cluster states in light nuclei populated through the (6Li,d) reaction

    Borello-Lewin, Thereza; Rodrigues, M.R.D.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Souza, M.A. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Cunsolo, A.; Cappuzzello, F. [Universita di Catania (Italy). Istituto Nazionale di Fisica Nucleare. Lab. Nazionali del Sud; Ukita, Gilberto Mitsuo [Universidade de Santo Amaro (UNISA), Sao Paulo, SP (Brazil). Fac. de Psicologia

    2011-07-01

    Full text: The alpha cluster correlation is an important concept in the nuclear physics of light nuclei. The main purpose of the research program in progress is the investigation of the alpha clustering phenomenon in (x{alpha}) and(x{alpha}+{nu}) nuclei through the ({sup 6}Li,d) alpha transfer reaction. In fact, there is scarce experimental information on the subject, in particular associated with resonant states predicted near (x{alpha}) and (x{alpha}+{nu}) thresholds. Measurements of the {sup 12},{sup 13}C({sup 6}Li,d) {sup 16},{sup 17}O reactions, at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique. The work is under way and an experimental energy resolution of 30 keV was obtained. Near the (4{alpha}) breakup threshold in {sup 16}O, three narrow alpha resonances, not previously measured, were detected, revealing important {alpha} + {sup 12}C(G.S.) components. One of these resonances corresponds to the known 0{sup +} state at 15.1 MeV[5] of excitation that has probably, according to Funaki et al., the gas like configuration of the 4{alpha} condensate state, with a very dilute density and a large component of {alpha} + {sup 12}C(Hoyle) configuration. As was already mentioned, our experimental information points to the necessity of including the {alpha} + {sup 12}C(G.S.) component in the wave function. (author)

  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. Investigations of 6LiIn1-xGaxSe2 semi-insulating crystals for neutron detection

    Wiggins, Brenden; Bell, Joseph; Burger, Arnold; Stassun, Keivan; Stowe, Ashley C.

    2015-08-01

    Neutron detectors are used for illicit material detection, neutron radiography, stellar investigations of chemical content including biological compounds in planetary terrain and to monitor nuclear power plant fuel products and radioactive waste. Li-containing chalcogenide materials are promising alternative thermal neutron detection materials due to the incorporation of the 6Li isotope at high density. 6LiInSe2 is limited in its effective thermal neutron efficiency by 115In neutron capture which results in gamma decay rather than charge creation. This study includes investigations of mixed crystalline material 6LiIn1-xGaxSe2 where the indium concentration is reduced by Ga substitution. The optical properties have been tuned by gallium substitution and radiation response has been observed.

  3. Photoassociation spectroscopy of long-range molecular states below the 2s + 3p 6Li2 asymptote

    Gross, Christian; Chaudhuri, Saptarishi; Gan, Jaren; Dieckmann, Kai

    2015-05-01

    We present photoassociation spectra of high-lying vibrational states of the interatomic potentials correlating to the 2s + 3p asymptote of 6Li2 . Starting from an atomic cloud in a magneto-optical trap we first drive a free-to-bound transition into a molecular bound state using a tunable ultra-violet laser. Thereafter we ionize these long-range molecules using a 532 nm laser and detect the resulting ions with a channeltron. We determine the absolute positions of the transitions with MHz precision utilizing a frequency comb based calibration. Lithium dimers are extensively studied theoretically using various models and methods. Spectroscopic measurements are crucial to test and benchmark these methods and are available for various electronic states and inter-nuclear distances of 6Li2 molecule. Our study provides the first experimental observation of long-range states of the 2s + 3p asymptote of 6Li2 .

  4. Integrated readout of organic scintillator and ZnS:Ag/6LiF for segmented antineutrino detectors.

    Kiff, Scott D.; Reyna, David; Monahan, James; Bowden, Nathaniel S.

    2010-11-01

    Antineutrino detection using inverse beta decay conversion has demonstrated the capability to measure nuclear reactor power and fissile material content for nuclear safeguards. Current efforts focus on aboveground deployment scenarios, for which highly efficient capture and identification of neutrons is needed to measure the anticipated antineutrino event rates in an elevated background environment. In this submission, we report on initial characterization of a new scintillation-based segmented design that uses layers of ZnS:Ag/{sup 6}LiF and an integrated readout technique to capture and identify neutrons created in the inverse beta decay reaction. Laboratory studies with multiple organic scintillator and ZnS:Ag/{sup 6}LiF configurations reliably identify {sup 6}Li neutron captures in 60 cm-long segments using pulse shape discrimination.

  5. Integrated readout of organic scintillator and ZnS:Ag/6LiF for segmented antineutrino detectors.

    Kiff, Scott D.; Reyna, David; Monahan, James (Drexel University, Philadelphia, PA); Bowden, Nathaniel S. (Lawrence Livermore National Laboratory, Livermore, CA)

    2010-10-01

    Antineutrino detection using inverse beta decay conversion has demonstrated the capability to measure nuclear reactor power and fissile material content for nuclear safeguards. Current efforts focus on aboveground deployment scenarios, for which highly efficient capture and identification of neutrons is needed to measure the anticipated antineutrino event rates in an elevated background environment. In this submission, we report on initial characterization of a new scintillation-based segmented design that uses layers of ZnS:Ag/{sup 6}LiF and an integrated readout technique to capture and identify neutrons created in the inverse beta decay reaction. Laboratory studies with multiple organic scintillator and ZnS:Ag/{sup 6}LiF configurations reliably identify {sup 6}Li neutron captures in 60 cm-long segments using pulse shape discrimination.

  6. Double-folding analysis of the 6Li + 58Ni reaction using the ab initio density distribution

    The elastic scattering angular distributions of the 6 Li + 58 Ni reaction are reanalyzed by using the double-folding model (DFM) within the framework of the optical model (OM) at energies near the Coulomb barrier, ELab = 9.9, 11.2, 12.1, 13.0 and 14.0 MeV. With this goal, for the first time, the no-core full configuration (NCFC) density distribution (DD) of the 6 Li nucleus is used in order to obtain the real potentials. Also, in order to see the validity of NCFC DD, another density distribution (Gaussian shape) of the 6 Li nucleus is used to obtain the real potentials in DF calculations. The results with NCFC DD are compared with Gaussian shape (GS) DD as well as the experimental data. It has been seen that the NCFC DD results are in agreement with the experimental data, giving better results than GS DD. (orig.)

  7. Energy loss of high velocity 6Li2+ ions in carbon foils in charge state non-equilibrium region

    Mean energy losses of high velocity H-like Li ions in thin carbon foils were measured in the charge state non-equilibrium region. Owing to the screening effect of the bound electron, the fixed-charge stopping power for 6Li2+ was smaller than that for 6Li3+. The projectile atomic number dependence of the fixed-charge stopping powers for H-like ions is discussed including our previous data of He, C and O ions with the same velocity. The present result is also compared with the theoretical prediction. (orig.)

  8. 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...

  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. 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.

  11. /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.

  12. 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)

  13. 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.)

  14. 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.

  15. 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

  16. 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...

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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...

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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...

  9. 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

  10. 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.

  11. 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.

  12. Quasi-bound alpha resonant states populated by the 12C(6Li, d) reaction

    Full text: The alpha cluster phenomenon in the light nuclei structure has been the subject of a long time investigation since the proposal of the Ikeda diagrams [1]. The main purpose of the research program in progress is the investigation of this phenomenon in (xα) and (xα+n) nuclei through the (6Li, d) alpha transfer reaction [2-4]. Alpha resonant states around the (4α) threshold in the nucleus 16O are the focus of the present contribution. In fact, the importance of these resonances at the elements production in stars is recognized, as primarily pointed out by Hoyle in 12C [6]. The existence of a rotational band with the α +12 C (Hoyle) cluster state structure was recently demonstrated by Ohkubo and Hirabayashi [6]. In order to explore this region of interest, measurements of the 12C(6Li, d)16O reaction up to 17 MeV of excitation at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique (plates Fuji G6B, 50 μm thick). Spectra associated with six scattering angles, from 5 deg to 29 deg in the laboratory frame, each one 50 cm along the focal surface, were measured. Several narrow resonances with a quasi-bound behavior embedded in the continuum were detected and the resolution of 25 keV allowed for the separation of doublets not resolved before [7,8]. The absolute cross sections and the respective deuteron angular distributions were determined and the analysis is in progress. [1] K. Ikeda et al., Prog. Theor. Phys. Suppl. E 68, 464 (1968); H. Horiuchi, K. Ikeda, and Y. Suzuki, ibid. 44, 225 (1978). [2] M.R.D.Rodrigues et al., in12th International Conference on Nuclear Reaction Mechanism, Varenna, Italy, edited by F. Cerutti and A. Ferrari , CERN Proceedings, 2010-2, pp. 331- 335. [3] T. Borello-Lewin et al., Proceedings of SOTANCP2, Brussels, Belgium 2010, edited by P. Descouvemount et al., Int. J. Mod. Mod. Phys E 20, 1018-1021 (2011). [4] T. Borello-Lewin et

  13. Alpha resonances excited in13C and 16O by the (6Li,d) reaction

    The investigation of a cluster correlations is the main purpose of the research program in progress, focusing on xα and xα + ν nuclei. The reactions 9Be(6Li,d)13C and 12C(6Li,d)16O measured at the bombarding energy of 25.5 MeV, employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique, were used to enhance a resonant states in 13C and 16O. An energy resolution of 20-40 keV was obtained and up to 15.5 MeV of excitation, in both nuclei, several resonances not previously measured, revealing a quasi-bound behavior, were detected. Focusing on 13C, the experimental angular distributions associated with the resonances just above the 9Be + α and 3α + ν thresholds[2] were compared with DWBA predictions. Seen at the 9Be + α threshold, a pure L = 4 transfer is indicated for each transition to the known 7/2- and (5/2-) states instead of L = 2 obtained in the former fit[3] to the integrated contribution. The narrow resonance detected at 12.3 MeV of excitation, close to the 3α + ν threshold and populated by an L = 2 transfer, reveals a 9Be(G.S.) + α component for the 1/2- cluster state candidate, 12C(Hoyle) + ν, at this threshold. Considering the 16O, states were revealed around the 4α threshold (14.44 MeV) and the upper limit resonant widths were obtained. The resonance at 14.670 MeV was reached by an L = 5 direct transfer in agreement with the 5- attribution. The upper limit width obtained, near the experimental resolution, is inconsistent with the usual experimental[4,5] and theoretical[6-7] interpretations of the 5- state revealed as a broad resonance in the same excitation energy region and considered to be a member of the Kπ = 0- band with the 12C(G.S.) + α structure. In the same excitation energy range, a narrow 5- resonance decaying to 12C(2+ 1), was predicted by Suzuki using a comprehensive semi-microscopic alpha cluster calculation, in agreement with the present findings. Haigh et al., in the investigation of the 12C

  14. 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

  15. 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.

  16. 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.)

  17. 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.

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

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

    2003-01-01

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

  19. NMR measurements of hyperpolarized 3He gas diffusion in high porosity silica aerogels

    Tastevin, Geneviève; Nacher, Pierre-Jean

    2005-01-01

    Hyperpolarized 3He is used to nondestructively probe by NMR the structure of custom-made and commercial silica aerogels (97% and 98.5% porous). Large spin-echo signals are obtained at room temperature and very low magnetic field (2mT) even with small mounts of gas. Attenuation induced by applied field gradients results from the combined effects of gas diffusion and confinement by the porous medium on atomic motion. Nitrogen is used as a buffer gas to reach equivalent 3He pressures ranging fro...

  20. 3He[pol](rvec e, e')X and the neutron electromagnetic form factors

    Recent data for the spin-dependent AT, and ATL, asymmetries in 3He[pol](rvec e, e') quasielastic scattering are reviewed. The neutron electric and magnetic form factors are extracted from the data using a plane wave impulse approximation (PWIA) model, and the model uncertainties are estimated. The extracted GMn is in agreement with the dipole prediction as well as with other recent experiments. No meaningful result for GEn is obtained due to large uncertainties and possible final-state interaction effects. At higher Q2, the determination of GEn in 3He[pol](rvec e,e') does appear feasible based on the plane wave impulse approximation (PWIA) predictions

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

    Hampson, T.M.M.; Bowley, R.M.; Brugel, D.; McHale, G.

    1988-12-01

    We have calculated the viscosity, thermal conductivity, and longitudinal spin diffusion coefficient in /sup 3/He-/sup 4/He 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 /sup 3/He 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. Application of gaseous absorbers for testing the fuel elements in nonstationary regimes. [/sup 3/He

    Andreev, V.I.; Egorenkov, P.M.; Kolyadin, V.I.; Kosilov, A.N.; Kuznetsov, Eh.M.; Potapenko, P.T.; Sivokon, V.P.; Fokin, A.B.; Yakovlev, V.V.

    1981-11-01

    A possibility of operative local control of power release in loop channels of a research reactor MR by means of a gaseous neutron absorber with /sup 3/He being of use as absorber is studied. The gas control system intended for the study of the WWER-1000 reactor fuel element serviceability in transients is described. The calculation-experimental investigation results of the dependence of power change of an experimental heat-generating assembly and reactivity on /sup 3/He pressure in the channel are presented. A conclusion on satisfactory efficiency of the described gas control system is made on the base of the analysis of the results obtained.

  3. Is there an {eta}{sup 3}He quasi-bound state?

    Wilkin, C. [Physics and Astronomy Department, UCL, London, WC1E 6BT (United Kingdom)], E-mail: cw@hep.ucl.ac.uk; Buescher, M. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Chiladze, D. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia (United States); Dymov, S. [Laboratory of Nuclear Problems, JINR, 141980 Dubna (Russian Federation); Hanhart, C.; Hartmann, M.; Hejny, V. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Kacharava, A. [High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia (United States); Physikalisches Institut II, Universitaet Erlangen-Nuernberg, 91058 Erlangen (Germany); Keshelashvili, I. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia (United States); Khoukaz, A. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Maeda, Y. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Mersmann, T.; Mielke, M. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Mikirtychiants, S. [High Energy Physics Department, Petersburg Nuclear Physics Institute, 188350 Gatchina (Russian Federation); Papenbrock, M. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Rathmann, F. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Rausmann, T. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany); Schleichert, R.; Stroeher, H. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Taeschner, A. [Institut fuer Kernphysik, Universitaet Muenster, 48149 Muenster (Germany)] (and others)

    2007-10-11

    The observed variation of the total cross section for the dp{yields}{sup 3}He{eta} reaction near threshold means that the magnitude of the s-wave amplitude falls very rapidly with the {eta} centre-of-mass momentum. It is shown here that recent measurements of the momentum dependence of the angular distribution imply a strong variation also in the phase of this amplitude. Such a behaviour is that expected from a quasi-bound or virtual {eta}{sup 3}He state. The interpretation can be investigated further through measurements of the deuteron or proton analysing powers and/or spin-correlations.

  4. Polarisation and compression of 3He for Magnetic Resonance Imaging purposes

    Magnetic Resonance Imaging is often used in medical science as a diagnostic tool for the human body. Conventional MRI uses the NMR signal from the protons of water molecules in tissue to image the interior of the patient's body. However, for certain areas such as the lungs and airways, the usage of a highly polarised gas yields better results. We are currently constructing an apparatus that uses polarised 3He gas to produce detailed images of those signal-deficient moyeties. We also plan to study possible uptake of polarised 3He gas by the circulatory system to image other organs

  5. Thermodynamic measurement of the magnetization curve of liquid 3He up to 200 Tesla

    The study of spin polarised liquid 3He provides new insight in the physics of Fermi liquids. The rapid melting technique offers a way to obtain transiently strongly polarised liquid 3He. We have improved this technique by melting the solid in a silver sinter. This opens the way to experiments on highly polarised liquid (up to 70%) at low temperatures (<100 mK). The use of this sinter results in a good thermal homogeneity of the sample. We applied our technique to measure the magnetisation curve up to fields as large as 200 T, providing essential information on the magnetism of this Fermi liquid. Other possible experiments are briefly discussed. (orig.)

  6. Precision Measurement of the n-3He Incoherent Scattering Length Using Neutron Interferometry

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

    2008-01-01

    We report the first measurement of the low-energy neutron-$^3$He incoherent scattering length using neutron interferometry: $b_i' = (-2.512\\pm 0.012{statistical}\\pm0.014{systematic})$ fm. This is in good agreement with a recent calculation using the AV18+3N potential. The neutron-$^3$He scattering lengths are important for testing and developing nuclear potential models that include three nucleon forces, effective field theories for few-body nuclear systems, and neutron scattering measurement...

  7. Optical generation of the first and second sounds in superfluid 3He-4He solutions

    An optical method of generation of the first and second sounds in superfluid 3He-4He solutions is proposed. The method is based on illumination by amplitude-modulated laser beam with wavelength corresponding to a region of absorption. Numerical calculations of pressure and temperature as a function of time are carried out. It was found that the presence of 3He isotopes in the solution provides strong coupling between these parameters and, as a result, the waves of the first sound involve oscillations of the temperature, while the waves of the second sound involve oscillations of the pressure

  8. An Approach to Unfold Neutron Spectra Measured by a 3He Semiconductor Detector

    In measurements of fast neutron spectra by a 3He semiconductor detector, the unfolding method is not usually required. The unfolding method based on principle of maximum likelihood that incorporates the Gaussian approximation of counting statistics is developed and implemented in the MLMHE31 numerical code for application in fast neutron spectrometry by 3He semiconductor detectors. The derived likelihood equations have been solved using method of the singular value decomposition of the response matrix. For this inverse problem, the detector responses were generated by the Monte Carlo technique. (author)

  9. The Nuclear Response in Delta-Isobar Region in the ($^3\\!$He,t) Reaction

    Dmitriev, V. F.

    1992-01-01

    The excitation of a $\\Delta$-isobar in a finite nucleus in charge--exchange ($^3\\!$He,t) reaction is discussed in terms of a nuclear response function. The medium effects modifying a $\\Delta$- and a pion propagation were considered for a finite size nucleus. The Glauber approach has been used for distortion of a $^3\\!$He and a triton in the initial and the final states. The effects determining the peak positions and its width are discussed. Large displacement width for the $\\Delta$ - h excita...

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

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

    2016-06-01

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

  11. 3He detector design for low-level transuranic waste assay

    From this study it appears that a logical configuration of 3He detectors imbedded in CH2 for nondestructive assay of low-level transuranic waste is: rho = 1 atmosphere, d = 2.54 cm, x = 5.08 cm, t = 15.24 cm, h = 61 cm, and N = 5. If a greater detector response is desired, the best way to achieve it is to first double the detector height, h, and then to increase the number of tubes, N, and/or increase the 3He density, rho

  12. Decoupling between first sound and second sound in $^3$He - superfluid $^4$He mixtures

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

    2016-01-01

    Bulk superfluid helium supports two sound modes: first sound is an ordinary pressure wave, while second sound is a temperature wave, unique to inviscid superfluid systems. These sound modes do not usually exist independently, but rather variations in pressure are accompanied by variations in temperature, and vice versa. We studied the coupling between first and second sound in dilute $^3$He - superfluid $^4$He mixtures, between 1.6 K and 2.2 K, at $^3$He concentrations ranging from 0 to 11 %,...

  13. SEOP polarized 3He Neutron Spin Filters for the JCNS user program

    Babcock, Earl; Salhi, Zahir; Theisselmann, Tobias; Starostin, Denis; Schmeissner, Johann; Feoktystov, Artem; Mattauch, Stefan; Pistel, Patrick; Radulescu, Aurel; Ioffe, Alexander

    2016-04-01

    Over the past several years the JCNS has been developing in-house applications for neutron polarization analysis (PA). These methods include PA for separation of incoherent from coherent scattering in soft matter studies (SANS), and online polarization for analysis for neutron reflectometry, SANS, GISANS and eventually spectroscopy. This paper will present an overview of the user activities at the JCNS at the MLZ and gives an overview of the polarization 3He methods and devices used. Additionally we will summarise current projects which will further support the user activities using polarised 3He spin filters.

  14. B phase with polar distortion in superfluid {sup 3}He in “ordered” aerogel

    Dmitriev, V. V., E-mail: dmitriev@kapitza.ras.ru; Senin, A. A.; Soldatov, A. A.; Surovtsev, E. V.; Yudin, A. N. [Russian Academy of Sciences, Kapitza Institute for Physical Problems (Russian Federation)

    2014-12-15

    The properties of the low-temperature superfluid phase of {sup 3}He in “nematically ordered” aerogel in which strands are almost parallel to one another are investigated by nuclear magnetic resonance methods. Such a strong anisotropy of the aerogel affects the phase diagram of {sup 3}He and the structure of superfluid phases. A theoretical model of the B phase with polar distortion is developed. It is shown that this model successfully describes the observed properties of the low-temperature phase.

  15. Neutron fluence determination at reactor filters by 3He proportional counters: Comparison of unfolding algorithms

    Multichannel pulse height measurements with a cylindrical 3He proportional counter obtained at a reactor filter of natural iron are taken to investigate the properties of three algorithms for neutron spectrum unfolding. For a systematic application of uncertainty propagation the covariance matrix of previously determined 3He response functions is evaluated. The calculated filter transmission function together with a covariance matrix estimated from cross-section uncertainties of the filter material is used as fluence pre-information. The results obtained from algorithms with and without pre-information differ in shape and uncertainties for single group fluence values, but there is sufficient agreement when evaluating integrals over neutron energy intervals

  16. Two-step mechanism of meson production in pd → 3HeX reaction

    It is shown that the two-step model of the reaction pd→3HeX (X η, η', ω, φ), involving the subprocesses pp → dπ+ and π+n →Xp allows to explain the form of energy dependence of experimental cross sections above the thresholds under assumption that the singlet part of the pp→dπ+ amplitude dominates in collinear kinematics. The spin-spin asymmetry for the reaction dp→3HeX has been found to be ∼ -1 in the forward-backward approximation. (author)

  17. Multi-elemental characterization of organic liquid samples by use of a 13 MeV 6Li3+ beam

    Evaporated amniotic fluid (AF) targets have been bombarded with a 13 MeV 6Li3+ beam. Forward angle data have served to identify the 1H(6Li,1H)6Li reaction as an alternative for hydrogen characterization of such organic samples. Detected 6Li ions elastically scattered from C, N, O, Na and Cl can also be used to determine the concentrations of these elements in AF. The analyzed AF samples have been diluted with distilled water. The effect of sample dilution on the improvement of spectrum energy resolution has been observed, confirming previous reports. The hydrogen concentration determined in the studied AF targets is shown to vary linearly with sample dilution. Two detector arrangements have been used to find out which detection scheme is the most convenient. The combination of a counter telescope and a single detector, set up at the same polar angle on the opposite side of the beam, seems to be the best choice to have a reliable particle identification and an adequate energy resolution simultaneously.

  18. Evaluation of repulsive core parameters in heavy ion interactions from an analysis of the 6Li+28Si elastic scattering

    An attempt has been made to evaluate short-range repulsive core parameters in the potential of 6Li and 28Si nuclei interaction. The required data are obtained as a result of simultaneous analysis of experimental angular distributions of 6Li+28Si elastic scattering at the collision energy Esub(Li)=30 and 154 MeV. The evaluation calculations for Esub(Li)=5.8-154 MeV are performed. The relation of the repulsive core with the equation of nuclear matter state is discussed. From the analysis of experimental data on elastic scattering of 6Li+28Si at Esub(Li)=30 and 154 MeV an optical potential describing elastic scattering 30 MeV of 6Li+28Si in a wide angle range THETA <= 172 deg is obtained. The most specific peculiarity of the potential obtained is the presence of strong repulsion at short distances (r <= 3.5 f) between nuclei mass centres. It is shown that the parameters of the repulsive core obtained can be roughly evaluated using the equations of state of nuclear matter while the depth of the potential real part (approximately 30 MeV) is in qualitative agreement with some other approaches in which ion-ion interaction is calculated theoretically

  19. On the hyperfine structures of the ground state(s) in the ${}^{6}$Li and ${}^{7}$Li atoms

    Frolov, Alexei M

    2016-01-01

    Hyperfine structure of the ground $2^{2}S-$states of the three-electron atoms and ions is investigated. By using our recent numerical values for the doublet electron density at the atomic nucleus we determine the hyperfine structure of the ground (doublet) $2^{2}S-$state(s) in the ${}^{6}$Li and ${}^{7}$Li atoms.

  20. Reactions 7Li(e,6He) pe' and 7Li(e,6Li) ne' at intermediate excitation energies

    The reactions 7Li(e,6He) pe' and 7Li(e,6Li) ne' have been studied at intermediate excitation energies. Angular distributions as well as energy distributions are presented. The experimental cross sections are compared to the results obtained from a simple model

  1. Neutron total and scattering cross sections of 6Li in the few MeV region

    Neutron total cross sections of 6Li are measured from approx. 0.5 to approx. 4.8 MeV at intervals of approx. 10 scattering angles and at incident-neutron intervals of approx.< 100 keV. Neutron differential inelastic-scattering cross sections are measured in the incident-energy range 3.5 to 4.0 MeV. The experimental results are extended to lower energies using measured neutron total cross sections recently reported elsewhere by the authors. The composite experimental data (total cross sections from 0.1 to 4.8 MeV and scattering cross sections from 0.22 to 4.0 MeV) are interpreted in terms of a simple two-level R-matrix model which describes the observed cross sections and implies the reaction cross section in unobserved channels; notably the (n;α)t reaction (Q = 4.783 MeV). The experimental and calculational results are compared with previously reported results as summarized in the ENDF/B-V evaluated nuclear data file

  2. Direct measurements of the absorption and spin-dependent scattering of thermal neutrons by 6Li

    To describe the interaction of slow neutrons (s waves) with nuclei of non-zero spin I it is necessary to introduce four parameters: b+, b- (scattering length for bound nuclei) and sigma+sub(c), sigma-sub(c) (capture cross section), the indices + and - referring respectively to the two possible channels for the interaction: I+1/2 and I-1/2. Having introduced the formalism of slow neutron scattering by a polarized target it is shown how B=(b+-b-)/(2I+1) and (sigma+sub(c)-sigma-sub(c)) may be determined by two kinds of experiments: analysis of the transmission of a polarized neutron beam as a function of the target polarization, and the pseudo-magnetism measurements. The notions of spin temperature, thermodynamics spin reservoirs and phenomena of nuclear relaxation and dynamic polarization in solids are reviewed and the experimental equipment is described briefly. The methods are applied to the measurement of capture and spin-dependent scattering amplitude for 6Li nuclei on a polycrystalline metallic sample and a monocrystalline lithium fluoride sample. The values found are: b+-b-=(0.38+-0.05) 10-12cm and sigma+sub(c)-sigma-sub(c)=(-1190+-40w) barn

  3. Analysis of 6Li Scattering at 240 MeV Using Different Nuclear Potentials

    Al-Ghamdi, A. H.; Ibraheem, Awad A.

    2016-06-01

    Angular distributions of the elastic and inelastic scattering cross sections of 6Li projectile on different heavy ion target nuclei including the 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn at energy of 240 MeV have been analyzed by using two different folded potentials based on the CDM3Y6 and São Paulo potentials for the real part of the optical potential, while the imaginary parts have a phenomenological Woods-Saxon shape. Coupled channel calculations for the low-lying 2+ state at 1.369, 1.779, 3.832, 1.454, 2.186, and 1.29 MeV for 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn, respectively, have been carried out, and the best fit values for B(EL) with the above models have been extracted by fitting the inelastic scattering cross section and compared with the values of previous works. The total reaction cross section and real and imaginary volume integrals have also been investigated.

  4. The Gas Motion Due To Non-Uniform Heating By 3He(n,p)3H Reactions In The Nuclear-Pumped3He -Lasers

    Çetin, Füsun

    2007-04-01

    In the nuclear pumped-lasers, the passage of these energetic charged particles through gas results in a non-uniform volumetric energy deposition. This spatial non-uniformity induces a gas motion, which results in density and hence refractive index gradients that affects the laser's optical behaviour. The motion of 3He gas in a closed cavity is studied when it experiences transient and spatially non-uniform volumetric heating caused by the passage of 3He(n,p)3H reaction products. Gas motion is described by the radial velocity field of gas flow. Spatial and temporal variations of radial gas velocity are calculated for various tube parameters by using a dynamic energy deposition model. In the calculations, it is assumed that the laser tube is irradiated with neutrons from the pulse at a peak power of 1200 MW corresponding to a maximum thermal neutron flux of 8×1016 n / cm2sn in the central channel of ITU TRIGA Mark II Reactor. Results are examined.

  5. 3D MRI of non-Gaussian 3He gas diffusion in the rat lung

    Jacob, Richard E.; Laicher, Gernot; Minard, Kevin R.

    2007-10-01

    In 3He magnetic resonance images of pulmonary air spaces, the confining architecture of the parenchymal tissue results in a non-Gaussian distribution of signal phase that non-exponentially attenuates image intensity as diffusion weighting is increased. Here, two approaches previously used for the analysis of non-Gaussian effects in the lung are compared and related using diffusion-weighted 3He MR images of mechanically ventilated rats. One approach is model-based and was presented by Yablonskiy et al., while the other approach utilizes the second order decay contribution that is predicted from the cumulant expansion theorem. Total lung coverage is achieved using a hybrid 3D pulse sequence that combines conventional phase encoding with sparse radial sampling for efficient gas usage. This enables the acquisition of nine 3D images using a total of only ˜1 L of hyperpolarized 3He gas. Diffusion weighting ranges from 0 s/cm 2 to 40 s/cm 2. Results show that the non-Gaussian effects of 3He gas diffusion in healthy rat lungs are directly attributed to the anisotropic geometry of lung microstructure as predicted by the Yablonskiy model, and that quantitative analysis over the entire lung can be reliably repeated in time-course studies of the same animal.

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

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

  7. Nuclear effects and neutron structure in deeply virtual Compton scattering off 3He

    Rinaldi, Matteo

    2014-01-01

    The study of nuclear generalized parton distributions (GPDs) could be a crucial achievement of hadronic physics since they open new ways to obtain new information on the structure of bound nucleons, in particular, to access the neutron GPDs. Here, the results of calculations of 3He GPDs in Impulse Approximation are presented. The calculation of the sum of GPDs H + E, and "tilde H", with the correct limits, will be shown. These quantities, at low momentum transfer, are largely dominated by the neutron contribution so that 3He is an ideal target for these kind of studies. Nevertheless the extraction of neutron information from future 3He data could be non trivial. A procedure, which takes into account nuclear effects encoded in IA, is presented. The calculation of H,E and "tilde H" allows also to evaluate the cross section asymmetries for deeply virtual compton scattering at Jefferson Lab kinematics. Thanks to these observations, DVCS off 3He could be an ideal process to access the neutron information in the ne...

  8. Study of the deeply bound hole states by the (3He,α) reaction

    The (3He,α) reactions at 110 - 120 MeV on even tin isotopes revealed the presence of the new (1g)-1 state at Ex = 6 -- 7 MeV with a spectroscopic factor comparable to the known (1g sub(9/2))-1 deeply bound hole state. (author)

  9. Observations of EUV Waves in 3He-Rich Solar Energetic Particle Events

    Bucik, R; Guo, L; Mason, G M; Wiedenbeck, M E

    2015-01-01

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

  10. Energy conversion options for ARIES-III - A conceptual D-3He tokamak reactor

    The potential for highly efficient conversion of fusion power to electricity provides one motivation for investigating D-3He fusion reactors. This stems from: (1) the large fraction of D-3He power produced in the forms of charged particles and synchrotron radiation which are amenable to direct conversion, and (2) the low neutron fluence and lack of tritium breeding constraints, which increase design flexibility. The design team for a conceptual D-3He tokamak reactor, ARIES-III, has investigated numerous energy conversion options at a scoping level in attempting to realize high efficiency. The energy conversion systems have been studied in the context of their use on one or more of three versions of a D-3He tokamak: a first stability regime device, a second stability regime device, and a spherical torus. The set of energy conversion options investigated includes bootstrap current conversion, compression-expansion cycles, direct electrodynamic conversion, electrostatic direct conversion, internal electric generator, liquid metal heat engine blanket, liquid metal MHD, plasma MHD, radiation boiler, scrape-off layer thermoelectric, synchrotron radiation conversion by rectennas, synchrotron radiation conversion by thermal cycles, thermionic/AMTEC/thermal systems, and traveling wave conversion. The original set of options is briefly discussed, and those selected for further study are described in more detail. The four selected are liquid metal MHD, plasma MHD, rectenna conversion, and direct electrodynamic conversion. Thermionic energy conversion is being considered, and some options may require a thermal cycle in parallel or series. 17 refs., 3 figs., 1 tab

  11. New type liquid He free {sup 3}He Cryostat using Commercial GM refrigerator

    Nishioka, T; Sumida, T; Takesaka, T; Kawamura, Y; Kato, H; Matsumura, M [Graduate School of Integrated Arts and Sciences, Kochi University, Kochi 780-8520 (Japan)], E-mail: nisioka@kochi-u.ac.jp

    2009-02-01

    We have succeeded to construct a novel {sup 3}He cryostat by improving a low cost commercial two stage Gifford-McMahon (GM) refrigerator whose cooling power is 0.3 W at 4.2 K. This main portion of this system consists of 4 K pot, 1 K pot, heat exchanger and {sup 3}He pot, which are connected to the second cold stage. The main portion is covered with the 1st radiation shield attached to the 1st cold stage and the {sup 3}He pot is covered with the 2nd radiation shield attached to the heat exchanger, where the 1st shield must be further covered with more than five layers of super-insulation films in order to realize {sup 3}He temperature. The achieved temperature is 0.4 K and persists over one day. The temperature oscillation is less than 1 mK below 4 K. The required time to attain the lowest temperature is typically about 8 hours. This system allows us to deal with almost all the low temperature experiments of condensed matter physics without requiring low temperature technique.

  12. 3He(α,γ7Be cross section measured using complementary techniques

    Carmona-Gallardo M.

    2014-03-01

    Full Text Available The astrophysical S-factor for the 3He(α,γ7Be reaction plays an important role in the Solar Standard Model and in the Big Bang Nucleosynthesis scenario. The advances from two recent experiments performed using complementary techniques at center of mass (C.M. energies between 1 and 3 MeV are discussed.

  13. The reaction mechanism of the (3HE,T) reaction and applications to nuclear structure

    1986-01-01

    In this thesis we present a study on the reaction meachanism of the (3He,t) reaction at 70-80 MeV bombarding energy and on structures of the residual nuclei excited in this reaction: 24-Al, 26-Al, 28-P, 32-Cl, 40-Sc, 42-Sc and 58-Cu... Zie: Summary

  14. Neutron scattering from liquid {sup 3}He at large momentum transfers

    Azuah, R.T. [Keele Univ. (United Kingdom). Dept. of Physics]|[Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Stirling, W.G. [Keele Univ. (United Kingdom). Dept. of Physics; Guckelsberger, K. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, Postfach 3345, 38116 Braunschweig (Germany); Scherm, R. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, Postfach 3345, 38116 Braunschweig (Germany)]|[Institut Laue-Langevin, BP 156X, F-38042 Grenoble (France); Glyde, H.R. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Bennington, S.M. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom); Taylor, A.D. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom)

    1995-08-01

    Neutron inelastic scattering measurements have been made on liquid {sup 3}He at 1.4 K for wave vectors between 9 and 20 A{sup -1}. The peak positions and widths are extracted and the mean kinetic energy determined. A new (theoretical) moment technique is used to investigate the momentum distribution and final-state effects. (orig.).

  15. sup 3 He neutron polarising filters -- theoretical comparison with supermirrors and Heusler alloy polarisers

    Cussen, L D; Hicks, T J

    2000-01-01

    There is currently intense interest in the development of gaseous sup 3 He neutron polarising transmission filters. The key areas of development are increasing the currently achievable levels of nuclear spin polarisation, pi, within the sup 3 He gas and improving the reliability of the devices. Recent work has identified 'quality factors' which can be used to determine the optimum thickness of such filters under various experimental conditions. The best achievable quality factor for a sup 3 He polariser with a given pi is determined. It is demonstrated that the optimum filter thickness depends only weakly on pi and is always approximately given by the dimensionless expression rho sigma lambda t=3.4 where rho is the density of sup 3 He atoms in the filter, sigma is the absorption cross section at a wavelength of 1 A, lambda is the neutron wavelength in A and t is the filter thickness. Quality factors are calculated for existing types of neutron polariser (supermirrors and Heusler alloy monochromators) as a fun...

  16. {sup 3}He neutron polarising filters -- theoretical comparison with supermirrors and Heusler alloy polarisers

    Cussen, L.D. E-mail: leocussen@vut.edu.au; Goossens, D.J.; Hicks, T.J

    2000-02-01

    There is currently intense interest in the development of gaseous {sup 3}He neutron polarising transmission filters. The key areas of development are increasing the currently achievable levels of nuclear spin polarisation, {pi}, within the {sup 3}He gas and improving the reliability of the devices. Recent work has identified 'quality factors' which can be used to determine the optimum thickness of such filters under various experimental conditions. The best achievable quality factor for a {sup 3}He polariser with a given {pi} is determined. It is demonstrated that the optimum filter thickness depends only weakly on {pi} and is always approximately given by the dimensionless expression {rho}{sigma}{lambda}t=3.4 where {rho} is the density of {sup 3}He atoms in the filter, {sigma} is the absorption cross section at a wavelength of 1 A, {lambda} is the neutron wavelength in A and t is the filter thickness. Quality factors are calculated for existing types of neutron polariser (supermirrors and Heusler alloy monochromators) as a function of instrumental parameters. These results are used to determine the 'break even' point for the new polarisers - the {pi} needed for the new polarisers to outperform existing types of polarisers. A quantitative discussion of regimes of usefulness of the different polariser types for all common instrument types is presented.

  17. Elastic scattering of 3He by 12C at 40.9 MeV energy

    The elastic scattering of 40.9 MeV 3He-particles from 12C was investigated in the framework of the simple one-channel optical model. An overall good fit could be obtained. The ambiguities of the real central potential are discussed. (author)

  18. Connection between the 3HE-enrichment and spectral index of solar energetic particles

    A model is presented which explains the observed tendency of events with large He-3/He-4 ratios to have steeper spectra. In this model preferential injection of He-3, acceleration by Alfven waves and Coulomb deceleration of ions are considered simultaneously. The observed tendency may be obtained as a result of competition between injection and acceleration processes

  19. η photoproduction off 3He: Search for η-mesic nuclei

    Photoproduction of η-mesons off 3He has been studied via the η→2γ and η→3π0 decay modes at the tagged photon beam of the Mainz MAMI accelerator using the combined 4π Crystal Ball/TAPS calorimeter. In a previous experiment, Pfeiffer et al. had reported evidence (although at low statistical significance) for the formation of a quasi-bound η-3He state. The present experiment aimed at an improved statistical quality for both the excitation function of coherent photoproduction on η-mesons off 3He and the peak-like structure in the excitation function of πo-p back-to-back pairs. The η-mesons have been identified by an invariant mass analysis of 2-photons (respectively 6-photons) events. In the both case also the constraints from the intermediate πo-invariant masses have been used. The coherent reaction γ3He→η3He has been selected by the suppression of events with observed recoil nucleons and by a missing energy analysis. Preliminary results for the excitation function show an extremely rapid rise at the production threshold similar to what has been observed in hadronic induced reactions at COSY. At the same time excitation function of π0-p pair shows the peak-like structure at the η-production threshold with much better statistic quality then the previous experiment. Also strong evidence for the existence of a resonance state has been formed.

  20. In situ polarized 3He system for the Magnetism Reflectometer at the Spallation Neutron Source.

    Tong, X; Jiang, C Y; Lauter, V; Ambaye, H; Brown, D; Crow, L; Gentile, T R; Goyette, R; Lee, W T; Parizzi, A; Robertson, J L

    2012-07-01

    We report on the in situ polarized (3)He neutron polarization analyzer developed for the time-of-flight Magnetism Reflectometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Using the spin exchange optical pumping method, we achieved a (3)He polarization of 76% ± 1% and maintained it for the entire three-day duration of the test experiment. Based on transmission measurements with unpolarized neutrons, we show that the average analyzing efficiency of the (3)He system is 98% for the neutron wavelength band of 2-5 Å. Using a highly polarized incident neutron beam produced by a supermirror bender polarizer, we obtained a flipping ratio of >100 with a transmission of 25% for polarized neutrons, averaged over the wavelength band of 2-5 Å. After the cell was depolarized for transmission measurements, it was reproducibly polarized and this performance was maintained for three weeks. A high quality polarization analysis experiment was performed on a reference sample of Fe/Cr multilayer with strong spin-flip off-specular scattering. Using a combination of the position sensitive detector, time-of-flight method, and the excellent parameters of the (3)He cell, the polarization analysis of the two-dimensional maps of reflected, refracted, and off-specular scattered intensity above and below the horizon were obtained, simultaneously. PMID:22852718

  1. Solar Sources of $^{3}$He-rich Solar Energetic Particle Events in Solar Cycle 24

    Nitta, Nariaki V; Wang, Linghua; Cohen, Christina M S; Wiedenbeck, Mark E

    2015-01-01

    Using high-cadence extreme-ultraviolet (EUV) images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we investigate the solar sources of 26 $^{3}$He-rich solar energetic particle (SEP) events at $\\lesssim$1 MeV nucleon$^{-1}$ that were well-observed by the Advanced Composition Explorer during solar cycle 24. Identification of the solar sources is based on the association of $^{3}$He-rich events with type III radio bursts and electron events as observed by Wind. The source locations are further verified in EUV images from the Solar and Terrestrial Relations Observatory, which provides information on solar activities in the regions not visible from the Earth. Based on AIA observations, $^{3}$He-rich events are not only associated with coronal jets as emphasized in solar cycle 23 studies, but also with more spatially extended eruptions. The properties of the $^{3}$He-rich events do not appear to be strongly correlated with those of the source regions. As in the previous...

  2. Precision measurement of thermal neutron beam densities using a 3He proportional counter

    Als-Nielsen, Jens Aage; Bahnsen, A.; Brown, W.K.

    1967-01-01

    of ±0.4%. Fundamental advantages of the method include the 1ν dependence of the 3He(n, p)T cross section up to 1 keV, and the assurance of homogeneity even for very small macroscopic cross sections, because of the gaseous detector material. Although the method requires a relatively clean neutron beam...

  3. Direct energy conversion and neutral beam injection for catalyzed D and D-3He tokamak reactors

    The calculated performance of single stage and Venetian blind direct energy converters for Catalyzed D and D-3He Tokamak reactors are discussed. Preliminary results on He pumping are outlined. The efficiency of D and T neutral beam injection is reviewed

  4. The effects of nuclear structure on generalized parton distributions of 3He

    Scopetta, S.

    2004-01-01

    The effect of the nuclear medium on generalized parton distributions (GPDs) is studied for the 3He nucleus, through a realistic microscopic analysis. In Impulse Approximation, Fermi motion and binding effects, evaluated by modern potentials, are found to be larger than in the forward case and very sensitive to the details of nuclear structure at short distances.

  5. First measurement of the vector analyzing power in muon capture by polarized muonic 3He

    This paper describes the first measurement of spin observables in nuclear muon capture by 3He. The sensitivity of spin observables to the pseudoscalar coupling is described. The triton asymmetry presented has to be corrected for small systematic effects in order to extract the vector analyzing power. The analysis of these effects is currently underway

  6. On temperature variations during 3He Polarization experiments in Pomeranchuk cells

    Geng, Q.; Rasmussen, Finn Berg

    1984-01-01

    Simple model calculations have been performed in relation to temperature changes in decompression experiments with Pomeranchuk cells, aiming at the production of spin polarized liquid **3He. Comparison with reported experiments indicates that thermal contact with the surroundings is too strong...

  7. Two dimensional sup 3 He adsorbed on Grafoil plated with a bilayer of HD

    Casey, A J

    2001-01-01

    sup 3 He films adsorbed on graphite preplated with a bilayer of hydrogen deuteride were studied by heat capacity measurements, in a nuclear demagnetisation cryostat down to temperatures below 1mK. The work focused on several areas of interest in 2D sup 3 He. Firstly coverages approaching solidification were investigated. Here we observed an apparent divergence in the effective mass of the sup 3 He quasi-particle as it approached solidification at a density in agreement with that predicted by the sq root 7x sq root 7 commensurate phase. We interpret this in terms of a Mott-Hubbard transition between a 2D Fermi liquid and a magnetically disordered solid occurring via the Brinkman-Rice scenario. We also observe finite temperature corrections to the linear heat capacity of the formT sup 2 going over to TlnT. Further investigations were carried out into solid coverages in which sup 3 He forms a two-dimensional quantum solid of spin 1/2 particles whose magnetism is influenced by reduced dimensionality, exchange and...

  8. Microscopic description of 3He - α scattering with density dependent interaction

    The elastic scattering for a light nuclear system 3He - α is analysed within the Generating Coordinates Method using a procedure formulated by Piza and Passos. The same numerical technique is used to describe the bond states and scattering properties. (A.C.A.S.)

  9. Kaonic {sup 3}He and {sup 4}He X-ray measurements in SIDDHARTA

    Ishiwatari, Tomoichi, E-mail: tomoichi.ishiwatari@assoc.oeaw.ac.at [Stefan-Meyer-Institut fuer subatomare Physik (Austria); Bazzi, M. [Laboratori Nazionali di Frascati, INFN (Italy); Beer, G. [University of Victoria, Department of Phys. and Astro. (Canada); Berucci, C. [Laboratori Nazionali di Frascati, INFN (Italy); Bombelli, L. [Politechno di Milano, Sez. di Elettronica (Italy); Bragadireanu, A. M. [Laboratori Nazionali di Frascati, INFN (Italy); Cargnelli, M. [Stefan-Meyer-Institut fuer subatomare Physik (Austria); Clozza, A.; Corradi, G.; Curceanu Petrascu, C.; D' Uffizi, A. [Laboratori Nazionali di Frascati, INFN (Italy); Fiorini, C. [Politechno di Milano, Sez. di Elettronica (Italy); Ghio, F.; Girolami, B. [INFN Sez. di Roma I and Inst. Superiore di Sanita (Italy); Guaraldo, C. [Laboratori Nazionali di Frascati, INFN (Italy); Hayano, R. S. [Univ. of Tokyo (Japan); Iliescu, M. [Laboratori Nazionali di Frascati, INFN (Italy); Iwasaki, M. [The Inst. of Phys. and Chem. Research, RIKEN (Japan); Kienle, P. [Tech. Univ. Muenchen, Physik Dep. (Germany); Levi Sandri, P. [Laboratori Nazionali di Frascati, INFN (Italy); and others

    2012-05-15

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

  10. The polarized 3He(d,p)4He reaction at Elab = 270Mev

    The 3He(d, p)4He reaction is one of the important processes in the primordial nuclearsynthesis of the universe. Furthermore, the reaction of a polarized 3He target with a polarized deuterium beam at E1ab = 270MeV would be an ambitious experiment in which a constraint on the deuteron D-state probability could be measured directly. Moreover, the reaction is interesting as an example of how to treat the five-body problem from a Faddeev theory point of view. Our approach involves coupled Faddeev equations for the 3He-p-n and d-d-p systems. Using two Faddeev equations, we obtained the scattering amplitudes 'Xhpn' and 'Xddp' for both the 3He-p-n and the d-d-p systems. Xhpn and Xddp were combined with each other by a proper normalization method. Finally, the differential cross section, the tensor analysing power, Ayy and Axx, the spin correlation coefficient, Cyy and Cxx, and the polarization correlation coefficient C// were investigated. We found that the amplitude Xhpn contributes mainly to the forward region of the differential cross section while Xddp contributes mainly to the backward region. Even for this calculation, the observables are smaller than the theoretical values at forward scattering angles. (author)

  11. Simulation of quantum field theory and gravity in superfluid 3He

    Superfluid phases of 3He are quantum liquids with the interacting fermionic and bosonic fields. In many respects they can simulate the interacting quantum fields in the physical vacuum. One can observe analogs of such phenomena as axial anomaly, vacuum polarization, zero-charge effect, fermionic charge of the vacuum, baryogenesis, ergo region, vacuum instability, etc. We discuss some topics using as an example several linear defects in 3He-A: (1) dis-gyration, which simulates the extremely massive cosmic string, (2) singular vortex, which is analogous to the spinning cosmic string, and (3) continuous vortex, whose motion causes the 'fermionic momentum' which is the analog of baryogenesis in early Universe. The production of the fermionic momentum by the vortex motion (the counterpart of the electroweak baryogenesis) has been recently measured in Manchester experiments on rotating superfluid 3He-A and 3He-B. To simulate the other phenomena, one needs a rather low temperature and high homogeneity, which probably can be attained under microgravity conditions

  12. Syntheses of [5-2H]-uracil, [5-2H]-cytosine, [6-2H]-uracil and [6-2H]-cytosine

    Syntheses of [5-2H]-, [6-2H]-uracil and [5-2H]-, [6-2H]-cytosine were investigated. The catalytic reaction of uracil or cytosine with 2H2 gas in alkaline media gave rise to [6-2H]-compounds almost exclusively. On the other hand, the reaction of 5-bromouracil or 5-bromocytosine with 2H2 gas gave rise to a mixture of [5-2H]-, [6-2H]- and [5-2H, 6-2H]-compounds depending on the experimental conditions. By controlling the temperature, the pressure of 2H2 gas and the amount of catalyst, [5-2H]-uracil and [5-2H]-cytosine were obtained. The isotopic distribution in each product was measured by 1H NMR spectroscopy combined with an HPLC method. (author)

  13. Towards {sup 6}Li-{sup 40}K ground state molecules

    Brachmann, Johannes Felix Simon

    2013-02-08

    The production of a quantum gas with strong long - range dipolar interactions is a major scientific goal in the research field of ultracold gases. In their ro - vibrational ground state Li-K dimers possess a large permanent dipole moment, which could possibly be exploited for the realization of such a quantum gas. A production of these molecules can be achieved by the association of Li and K at a Feshbach resonance, followed by a coherent state transfer. In this thesis, detailed theoretical an experimental preparations to achieve state transfer by means of Stimulated Raman Adiabatic Passage (STIRAP) are described. The theoretical preparations focus on the selection of an electronically excited molecular state that is suitable for STIRAP transfer. In this context, molecular transition dipole moments for both transitions involved in STIRAP transfer are predicted for the first time. This is achieved by the calculation of Franck-Condon factors and a determination of the state in which the {sup 6}Li-{sup 40}K Feshbach molecules are produced. The calculations show that state transfer by use of a single STIRAP sequence is experimentally very well feasible. Further, the optical wavelengths that are needed to address the selected states are calculated. The high accuracy of the data will allow to carry out the molecular spectroscopy in a fast and efficient manner. Further, only a comparatively narrow wavelength tuneability of the spectroscopy lasers is needed. The most suitable Feshbach resonance for the production of {sup 6}Li-{sup 40}K molecules at experimentally manageable magnetic field strengths is occurring at 155 G. Experimentally, this resonance is investigated by means of cross-dimensional relaxation. The application of the technique at various magnetic field strengths in the vicinity of the 155 G Feshbach resonance allows a determination of the resonance position and width with so far unreached precision. This reveals the production of molecules on the atomic side

  14. Studies on the light heavy ion system 6Li+16O

    In the present thesis the system 6Li+16O is studied in the range of the Coulomb threshold. The measured excitation functions exhibit almost without exception correlatedly occurring structures at Elab=5.4 MeV respectively 6.5 MeV (this corresponds to Ex(22Na)=18.5 MeV respectively 19.3 MeV). A detailed statistical analysis consisting of the calculation of the fluctuation band widths in the sense of the Ericson theory, the peak-counting analysis, the Fourier analysis, the auto-/cross-correlation analysis, as well as the calculation of the energy-dependent cross correlation and deviation functions identifies these phenomena as resonances (99% confidence limit). Further structures at Elab=4.7 and 7.8 MeV (corresponds toEx=17.9 respectively 20.2 MeV) reach the 90% confidence level. The mean coherence width resulted to Γ ≅ 130 keV and lies by this distinctly below the experimentally determined resonance widths of 350 keV ≤Γtot≤800 keV. The positions of the resonances can be well described by the assumption of a K=1 rotational band in the nucleus 22Na. Beside the model-dependent spin assignment the distribution of the angular momenta in the entrance channel suggests a negative parity of the band. By means of the experimentally determined linear cross correlation coefficients for isobaric analogue decay channels furthermore the Coulomb matrix element is determined to x>=1.5 keV. The comparison with the mean level width of the compound nucleus 22Na at excitation energies around 19 MeV indicates an extremely low Isospin violation. (orig./HSI)

  15. 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 electron energies E0=855, 675, 600, and 555 MeV. The overall features of the data for energy transfers of ω=370 to 430 MeV with pions detected along the momentum transfer axis 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 at Q2=0.045(GeV/c)2. The longitudinal part of the cross section in the π+ channel does not contradict with the assumption of a preformed Δ++. copyright 1996 The American Physical Society

  16. Measurement of the3He permeability of DT-filled fused silica inertial confinement fusion (ICF) targets to study the effects of3He on neutron emission during implosion

    A set of laser implosion experiments were conducted at the OMEGA laser at the Univ. of Rochester, Laboratory for Laser Energetics (LLE) to study the effect of He concentration in DT-filled target shells on fusion yield in ICF implosions.. Eleven laser fusion shells consisting of 1100-μm diameter, hollow, fused silica spheres with 4.6 to 4.7-μm-thick walls were loaded with 520 kPa of deuterium-tritium (DT) and then with 3He (101.3 or 520 kPa). The 3He permeabilities of the shells were determined by measuring the pressure rate of rise into a system with known volume. A mathematical method was developed that relied on the experimental fill pressure and time, and the rate of rise data to solve differential equations using MathCAD to simultaneously calculate 3He permeability and initial 3He partial pressure inside the shell. Because of the high permeation rate for 3He out of the shells compared to that for DT gas, shells had to be recharged with 3He immediately before being laser imploded or 'shot' at LLE. The 3He partial pressure in each individual shell at shot time was calculated from the measured 3He permeability. Two different partial pressures of 3He inside the shell were shown to reduce neutron and gamma yields during implosion. (authors)

  17. Precise determination of 6Li cold collision parameters by radio-frequency spectroscopy on weakly bound molecules

    We employ radio-frequency spectroscopy on weakly bound 6Li2 molecules to precisely determine the molecular binding energies and the energy splittings between molecular states for different magnetic fields. These measurements allow us to extract the interaction parameters of ultracold 6Li atoms based on a multichannel quantum scattering model. We determine the singlet and triplet scattering lengths to be as=45.167(8)a0 and at=-2140(18)a0 (1a0=0.052 917 7 nm), and the positions of the broad Feshbach resonances in the energetically lowest three s-wave scattering channels to be 83.41(15), 69.04(5), and 81.12(10) mT

  18. Li2TiO3 pebbles reprocessing, recovery of 6Li as Li2CO3

    A process for obtaining Li2CO3 from Li2TiO3 powder by wet chemistry was developed. This is considered useful in view of the recovery of 6Li isotope from a lithium titanate breeder burned up to its end of life in a fusion reactor. The process was optimized with respect to the chemical attack of titanate and the precipitation of carbonate from aqueous solutions to get a powder, with the chemical and morphological characteristics, suitable for its re-exploitation in the fabrication of Li2TiO3 pebbles. Reprocessing was also planned to adjust the 6Li concentration to the desired value and to obtain homogeneous distribution in the powder batch. Further development concerning reprocessing of sintered Li2TiO3 pebbles is in progress exploiting the results obtained with lithium titanate powders. (orig.)

  19. Li2TiO3 pebbles reprocessing, recovery of 6Li as Li2CO3

    A process for obtaining Li2CO3 from Li2TiO3 powder by wet chemistry was developed. This is considered useful in view of the recovery of the 6Li isotope from lithium titanate breeder burned to its end of life in a fusion reactor. The process was optimized with respect to the chemical attack of titanate and the precipitation of carbonate from aqueous solutions to get a powder with chemical and morphological characteristics suitable for its reexploitation in the fabrication of Li2TiO3 pebbles. Reprocessing was also planned to adjust the 6Li concentration to the desired value and to obtain a homogeneous distribution in the powder batch. Further development concerning reprocessing of sintered Li2TiO3 pebbles is in progress exploiting the results obtained with lithium titanate powders

  20. Astrophysical S-factor for $^6$Li$(p,\\gamma)$$^7$Be in the coupled-channel Gamow shell model

    Dong, G X; Michel, N; Płoszajczak, M

    2015-01-01

    We have applied the Gamow shell model (GSM) in the coupled-channel representation to study the astrophysical $S$-factor for the proton radiative capture reaction of $^6$Li. Reaction channels are built by coupling the proton wave function expanded in different partial waves with the GSM wave functions of the ground state ($1^+$) and the excited states ($3^+_1$, $0^+_1$ and $2^+_1$) of $^6$Li. All relevant $E1$, $M1$, and $E2$ transitions from the initial continuum states in $^7$Be to the final bound states (${3/2}^-_1$ and ${1/2}^-_1$) states are included. It is found that the calculated total astrophysical $S$ factor for this reaction agrees well with the experimental data.

  1. Astrophysical S-factor for 6Li(ρ, γ)7Be in the coupled-channel Gamow shell model

    Dong, G. X.; Fossez, K.; Michel, N.; Płoszajczak, M.

    2016-02-01

    We have applied the Gamow shell model (GSM) in the coupled-channel representation to study the astrophysical S-factor for the proton radiative capture reaction of 6Li. Reaction channels are built by coupling the proton wave function expanded in different partial waves with the GSM wave functions of the ground state (1+) and the excited states (31+, 01+ and 21+) of 6Li. All relevant E1, M1, and E2 transitions from the initial continuum states in 7Be to the final bound states (3/21- and 1/21-) are included. It is found that the calculated total astrophysical S factor for this reaction agrees well with the experimental data.

  2. Neutron detection and identification using ZnS:Ag/{sup 6}LiF in segmented antineutrino detectors

    Kiff, Scott D., E-mail: skiff@sandia.gov [Sandia National Laboratories, 7011 East Avenue, Livermore, CA 94550 (United States); Bowden, Nathaniel [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Lund, Jim; Reyna, David [Sandia National Laboratories, 7011 East Avenue, Livermore, CA 94550 (United States)

    2011-10-01

    Antineutrino detection using inverse beta-decay conversion has demonstrated capability to measure nuclear reactor power and fissile material content for nuclear safeguards. Current efforts focus on aboveground deployment scenarios, for which a successful background rejection strategy will be needed to measure the anticipated antineutrino event rates. In this paper, we report on initial studies to quantify the intrinsic capture efficiency and particle identification capabilities of a new scintillation-based segmented design that uses layers of ZnS:Ag/{sup 6}LiF to capture and identify neutrons created in the inverse beta-decay reaction. Laboratory efficiency measurements are consistent with MCNP5 calculations, estimating {sup 6}Li neutron conversion efficiency above 50% for practical full-scale detector configurations.

  3. Experiment E89-044 on the Quasielastic 3He(e,e'p) Reaction at Jefferson Laboratory

    E. Penel-Nottaris

    2004-07-07

    The Jefferson Lab Hall A E89-044 experiment has measured the 3He(e,e'p) reaction cross-sections. The extraction of the longitudinal and transverse response functions for the two-body break-up 3He(e,e'p)d reaction in parallel kinematics allows the study of the bound proton electromagnetic properties inside the 3He nucleus and the involved nuclear mechanisms beyond plane wave approximations.

  4. Simultaneous measurement of angular distribution of elastic scattering for 6Li, 7Be, and 8B in 58Ni

    The experimental angular distributions of elastic scattering for the projectiles 6Li, 7Be, 8B in 58Ni were obtained. Using the Optical model with a Woods-Saxon potential form, as much for the real part as for the imaginary one, an adjustment to the experimental data varying only the depth of the imaginary part of the potential is made. A comparison of the results obtained for each projectile is made. (Author)

  5. Influence of the separation of the centre-of-mass motion on the charge form factor of /sup 6/Li

    Bouten, M. (Limburgs Universitair Centrum (Belgium)); Bouten, M.C. (Centre d' Etude de l' Energie Nucleaire, Mol (Belgium))

    1982-12-01

    An exact calculation is carried out for the charge form factor of /sup 6/Li using a wavefunction for the ground state which depends on the internal coordinates only and which contains a short-range correlation factor of the Jastrow type. A very good fit to the experimental data can be obtained by adjusting the parameters in the wavefunction. It is found that the optimum value of these parameters depends sensitively on the way the centre-of-mass coordinate is eliminated.

  6. Probing Bogoliubov Quasiparticles in Superfluid ^3He with a `Vibrating-Wire Like' MEMS Device

    Defoort, M.; Dufresnes, S.; Ahlstrom, S. L.; Bradley, D. I.; Haley, R. P.; Guénault, A. M.; Guise, E. A.; Pickett, G. R.; Poole, M.; Woods, A. J.; Tsepelin, V.; Fisher, S. N.; Godfrin, H.; Collin, E.

    2016-05-01

    We have measured the interaction between superfluid ^3He-B and a micro-machined goalpost-shaped device at temperatures below 0.2 T_c. The measured damping follows well the theory developed for vibrating wires, in which the Andreev reflection of quasiparticles in the flow field around the moving structure leads to a nonlinear frictional force. At low velocities, the damping force is proportional to velocity, while it tends to saturate for larger excitations. Above a velocity of 2.6 mm s^{-1}, the damping abruptly increases, which is interpreted in terms of Cooper-pair breaking. Interestingly, this critical velocity is significantly lower than that reported with other mechanical probes immersed in superfluid ^3He. Furthermore, we report on a nonlinear resonance shape for large motion amplitudes that we interpret as an inertial effect due to quasiparticle friction, but other mechanisms could possibly be invoked as well.

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

    Second-sound velocities and osmotic pressures are analyzed to obtain the first experimental values for the Landau compressibility parameter F0/sup s/ in 3He-4He solutions. Data are presented as a function of pressure and 3He concentration, and are compared to theoretical predictions. The square of the second-sound velocity at finite temperature is found to be accurately proportional to the internal energy of a perfect Fermi gas. Using inertial effective masses given by the Landau-Pomeranchuk theory, the square of the velocity is found to separate into two parts: a temperature-dependent part characterized completely by ideal Fermi-gas behavior and a temperature-independent part containing all the Fermi-liquid corrections. This is related to a similar separation found in the osmotic pressure

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

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

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

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

  10. Constraining short-range spin-dependent forces with polarized $^3$He

    Guigue, Mathieu; Petukhov, Alexander K; Pignol, Guillaume

    2015-01-01

    We have searched for a short-range spin-dependent interaction using the spin relaxation of hyperpolarized $^3$He. Such a new interaction would be mediated by a hypothetical light scalar boson with \\CP-violating couplings to the neutron. The walls of the $^3$He cell would generate a pseudomagnetic field and induce an extra depolarization channel. We did not see any anomalous spin relaxation and we report the limit for interaction ranges $\\lambda$ between $1$ and $100~\\rm{\\mu m}$: $g_sg_p \\lambda ^2 \\leq 2.6\\times 10^{-28}~\\mathrm{m^2}\\, ( 95~\\%\\, \\mathrm{C.L.})$, where $g_s$($g_p$) are the (pseudo)scalar coupling constant, improving the previous best limit by 1 order of magnitude.

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

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

    2010-05-01

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

  12. Study of the pd(dp) -> 3He pi pi reactions close to threshold

    Bellemann, F; Bisplinghoff, J; Bohlscheid, G; Ernst, J; Henrich, C; Hinterberger, F; Ibald, R; Jahn, R; Joosten, R; Kilian, K; Kozela, A; Machner, H; Magiera, A; Munkel, J; von Neumann-Cosel, P; von Rossen, P; Schnitker, H; Scho, K; Smyrski, J; Toelle, R; Wilkin, C

    2016-01-01

    New experimental data on the pd -> 3He pi+ pi- reaction obtained with the COSY-MOMO detector below the three-pion threshold are presented. The reaction was also studied in inverse kinematics with a deuteron beam and the higher counting rates achieved were especially important at low excess energies. The comparison of these data with inclusive pd -> 3He+X rates allowed estimates also to be made of pi0 pi0 production. The results confirm our earlier findings that close to threshold there is no enhancement at low excitation energies in the pi+ pi- system, where the data seem largely suppressed compared to phase space. Possible explanations for this behavior, such as strong p- waves in the pi+pi- -system or the influence of two-step processes, are explored.

  13. Dynamical Behavior of Core 3 He Nuclear Reaction-Diffusion Systems and Sun's Gravitational Field

    DU Jiulin; SHEN Hong

    2005-01-01

    The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analyses of the system are made in this paper by using the theory of nonequilibrium dynamics. It is showed that, in the nuclear reaction regions extending from the center to about 0.38 times of the radius of the sun, the gravitational field enables the core 3He nuclear reaction-diffusion system to become unstable and, after the instability, new states to appear in the system have characteristic of time oscillation. This may change the production rates of both 7Be and 8B neutrinos.

  14. 7Li(3He,p)9Be reaction and primordial nucleosynthesis

    The differential cross section for the 7Li(3He, p)9Be reaction has been measured in 50 keV intervals at 8 angles (15deg-160deg) in the energy range from Ec.m.=0.5 to 2.0 MeV, and total cross sections were determined from these data. Since this reaction has been noted as being of possible importance in primordial nucleosynthesis, its astrophysical S-factor was calculated from the data. In addition, the S-factor for the 7Li(3H, n)9Be reaction, also of importance in primordial nucleosynthesis, was estimated from the 7Li(3He, p)9Be data and its thermonuclear reaction rate was calculated. (orig.)

  15. Neutron radiography of a static density gradient of 3He gas at cryogenic temperatures

    Wichmann, G.; Antognini, A.; Eggenberger, A.; Kirch, K.; Piegsa, F. M.; Soler, U.; Stahn, J.; Taqqu, D.

    2016-04-01

    We demonstrate a stationary helium gas density gradient which is needed for a proposed novel low-energy μ+ beam line. In a closed system with constant pressure the corresponding density gradient is only a function of the temperature. In a neutron radiography experiment two gas cells with different geometries were filled with 3He gas at constant pressures of about 10 mbar. Temperatures in the range from 6 K to 40 K were applied and density distributions with a maximum to minimum density ratio of larger than 3 were realized. The distribution was investigated employing the strongly neutron absorbing isotope 3He. A simple one-dimensional approach derived from Fourier's law describes the obtained gas density with a deviation < 2 %.

  16. Generalized Parton Distributions of 3He and the Neutron Orbital Structure

    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 effects included in the IA analysis in the extraction procedure, even at moderate values of the momentum transfer, is proposed. Coherent DVCS arises therefore as a crucial experiment to access, for the first time, the neutron GPDs and the orbital angular momentum of the partons in the neutron. (author)

  17. Generalized Parton Distributions of 3He and the Neutron Orbital Structure

    Rinaldi, M.; Scopetta, S.

    2013-08-01

    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 effects included in the IA analysis in the extraction procedure, even at moderate values of the momentum transfer, is proposed. Coherent DVCS arises therefore as a crucial experiment to access, for the first time, the neutron GPDs and the orbital angular momentum of the partons in the neutron.

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

    Rinaldi, Matteo; 10.1007/s00601-013-0603-7

    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 effects included in the IA analysis in the extraction procedure, even at moderate values of the momentum transfer, is proposed. Coherent DVCS arises therefore as a crucial experiment to access, for the first time, the neutron GPDs and the orbital angular momentum of the partons in the neutron.

  19. A Light-Front Approach to the 3He Spectral Function

    The analysis of semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, aimed at the extraction of the quark transverse-momentum distributions in the neutron, requires the use of a distorted spin-dependent spectral function for 3He, which takes care of the final state interaction effects. This quantity is introduced in the non-relativistic case, and its generalization in a Poincaré covariant framework, in plane wave impulse approximation for the moment being, is outlined. Studying the light-front spin-dependent spectral function for a J = 1/2 system, such as the nucleon, it is found that, within the light-front dynamics with a fixed number of constituents and in the valence approximation, only three of the six leading twist T-even transverse-momentum distributions are independent. (author)

  20. Concept definition of an FRC/DD-3He advanced fusion reactor

    Posibilities of advanced fusion fuel cycle reactors are investigated. Characteristics of various D - D fusion fuel cycles are clarified and which magnetic confinement method can fit the most efficient advanced fuel cycle reactor is examined. A concept definition is considered for an advanced fusion reactor with DD - 3He fuel cycle in which the plasma is confined in a field-reversed configuration or field-reversed mirror. The concept definition is developed with emphasis on the feasibility of a steady-state self-ignited DD - 3He plasma with temperatures of 100 keV, the production method, the formation of ambipolar potential in the ambient plasma and the design of plasma energy direct convertor. (author)