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Sample records for dineutrons

  1. First Observation of Ground State Dineutron Decay: Be16

    NASA Astrophysics Data System (ADS)

    Spyrou, A.; Kohley, Z.; Baumann, T.; Bazin, D.; Brown, B. A.; Christian, G.; Deyoung, P. A.; Finck, J. E.; Frank, N.; Lunderberg, E.; Mosby, S.; Peters, W. A.; Schiller, A.; Smith, J. K.; Snyder, J.; Strongman, M. J.; Thoennessen, M.; Volya, A.

    2012-03-01

    We report on the first observation of dineutron emission in the decay of Be16. A single-proton knockout reaction from a 53MeV/u B17 beam was used to populate the ground state of Be16. Be16 is bound with respect to the emission of one neutron and unbound to two-neutron emission. The dineutron character of the decay is evidenced by a small emission angle between the two neutrons. The two-neutron separation energy of Be16 was measured to be 1.35(10) MeV, in good agreement with shell model calculations, using standard interactions for this mass region.

  2. Constraints on a possible dineutron state from pionless EFT

    NASA Astrophysics Data System (ADS)

    Hammer, H.-W.; König, Sebastian

    2014-09-01

    We investigate the sensitivity of the three-nucleon system to changes in the neutron-neutron scattering length to next-to-leading order in the pionless effective field theory, focusing on the triton-3He binding energy difference and neutron-deuteron elastic scattering. Due to the appearance of a proton-deuteron three-body counterterm at this order, the triton-3He binding energy difference remains consistent with the experimental value even for large positive neutron-neutron scattering lengths while the elastic neutron-deuteron scattering phase shifts are insensitive. We conclude that a bound dineutron cannot be excluded to next-to-leading order in pionless EFT.

  3. Conventional BCS, unconventional BCS, and non-BCS hidden dineutron phases in neutron matter

    NASA Astrophysics Data System (ADS)

    Khodel, V. A.; Clark, J. W.; Shaginyan, V. R.; Zverev, M. V.

    2014-09-01

    The nature of pairing correlations in neutron matter is re-examined. Working within the conventional approximation in which the nn pairing interaction is provided by a realistic bare nn potential fitted to scattering data, it is demonstrated that the standard BCS theory fails in regions of neutron number density, where the pairing constant λ, depending crucially on density, has a non-BCS negative sign. We are led to propose a non-BCS scenario for pairing phenomena in neutron matter that involves the formation of a hidden dineutron state. In low-density neutron matter, where the pairing constant has the standard BCS sign, two phases organized by pairing correlations are possible and compete energetically: a conventional BCS phase and a dineutron phase. In dense neutron matter, where λ changes sign, only the dineutron phase survives and exists until the critical density for termination of pairing correlations is reached at approximately twice the neutron density in heavy atomic nuclei.

  4. Dineutron correlations in quasi-two-dimensional systems in a simplified model, and possible relation to neutron-rich nuclei

    SciTech Connect

    Kanada-En'yo, Yoshiko; Hinohara, Nobuo; Suhara, Tadahiro; Schuck, Peter

    2009-05-15

    Two-neutron correlation in the {sup 1}S channel in quasi-two-dimensional (2D) neutron systems at zero temperature is studied by means of the BCS theory with finite-range effective nuclear forces. The dineutron correlation in low density neutron systems confined in an infinite slab is investigated in a simplified model that neutron motion of one direction is frozen. When the slab is thin enough, two neutrons form a tightly bound dineutron with a small size in the quasi-2D system, and a Bose dineutron gas is found in low density limit. With increase of Fermi momentum, the neutron system changes from the Bose-gas phase to the superfluid Cooper pair phase. The density dependence of the neutron pairing shows the BCS-BEC crossover phenomena at finite low-density region. In the transition region, the size shrinking of neutron pair and enhancement of pairing gap are found. The relation to dineutron correlation at surface of neutron-rich nuclei is also discussed.

  5. Cluster aspects of p-shell and sd-shell nuclei

    SciTech Connect

    Kanada-En'yo, Y.; Kobayashi, F.; Suhara, T.; Kimura, M.; Taniguchi, Y.

    2011-05-06

    We report some topics on cluster structures studied by using a theoretical method of antisymmetrized molecular dynamics(AMD). Cluster features of p-shell and sd-shell nuclei are discussed. In particular, three alpha cluster structures in the excited states of {sup 12}C and {sup 14}C are focused. Dineutron correlations in neutron-rich nuclei are also discussed.

  6. Big bang nucleosynthesis: The strong nuclear force meets the weak anthropic principle

    SciTech Connect

    MacDonald, J.; Mullan, D. J.

    2009-08-15

    Contrary to a common argument that a small increase in the strength of the strong force would lead to destruction of all hydrogen in the big bang due to binding of the diproton and the dineutron with a catastrophic impact on life as we know it, we show that provided the increase in strong force coupling constant is less than about 50% substantial amounts of hydrogen remain. The reason is that an increase in strong force strength leads to tighter binding of the deuteron, permitting nucleosynthesis to occur earlier in the big bang at higher temperature than in the standard big bang. Photodestruction of the less tightly bound diproton and dineutron delays their production to after the bulk of nucleosynthesis is complete. The decay of the diproton can, however, lead to relatively large abundances of deuterium.

  7. Observation of gravity decays of multiple-neutron nuclei during cold fusion

    SciTech Connect

    Matsumoto, T. . Dept. of Nuclear Engineering)

    1992-08-01

    The Nattoh model predicted that multiple-neutron nuclei such as quad-neutrons can be produced during cold fusion, and the gravity decays of the quad-neutrons were recorded on nuclear emulsions. Several different traces that might be produced by the gravity decays of di-neutron and multiple-neutron nuclei have been successfully observed. The mechanisms of the production of multiple-neutron nuclei are discussed in this paper.

  8. Structure of the spatial periphery of the 11Li and 11Be isobars

    NASA Astrophysics Data System (ADS)

    Galanina, L. I.; Zelenskaya, N. S.

    2016-07-01

    On the basis of the shell model with an extended basis, the structure of 9Li-9Be to 11Li-11Be nuclei is examined with allowance for the competition of jj coupling and Majorana exchange forces via considering the sequential addition of neutrons, and the respective wave functions are determined. A formalism for calculating the spectroscopic factor for a dineutron and for individual neutrons in nuclei whose wave functions incorporate the mixing of shell configurations is developed. The reactions 9Li( t, p)11Li and 9Be( t, p)11Be treated with allowance for the mechanisms of dineutron stripping and a sequential transfer of two neutrons are considered as an indicator of the proposed structure of lithium and berylliumisotopes. The parameters of the optical potentials, the wave functions for the bound states of transferred particles, and the interaction potentials corresponding to them are determined from a comparison of the theoretical angular distribution of protons from the reaction 9Be( t, p)11Be with its experimental counterpart. It is shown that a dineutron periphery of size about 6.4 fm is present in the 11Li nucleus and that a single-neutron periphery of size about 8 fm is present in the 11Be nucleus.

  9. Structure of the spatial periphery of the {sup 11}Li and {sup 11}Be isobars

    SciTech Connect

    Galanina, L. I. Zelenskaya, N. S.

    2016-07-15

    On the basis of the shell model with an extended basis, the structure of {sup 9}Li-{sup 9}Be to {sup 11}Li-{sup 11}Be nuclei is examined with allowance for the competition of {sup jj} coupling and Majorana exchange forces via considering the sequential addition of neutrons, and the respective wave functions are determined. A formalism for calculating the spectroscopic factor for a dineutron and for individual neutrons in nuclei whose wave functions incorporate the mixing of shell configurations is developed. The reactions {sup 9}Li(t, p){sup 11}Li and {sup 9}Be(t, p){sup 11}Be treated with allowance for the mechanisms of dineutron stripping and a sequential transfer of two neutrons are considered as an indicator of the proposed structure of lithium and berylliumisotopes. The parameters of the optical potentials, the wave functions for the bound states of transferred particles, and the interaction potentials corresponding to them are determined from a comparison of the theoretical angular distribution of protons from the reaction {sup 9}Be(t, p){sup 11}Be with its experimental counterpart. It is shown that a dineutron periphery of size about 6.4 fm is present in the {sup 11}Li nucleus and that a single-neutron periphery of size about 8 fm is present in the {sup 11}Be nucleus.

  10. Cold Fusion Dark Matter and Dark Energy

    NASA Astrophysics Data System (ADS)

    Levi, Mark

    2009-05-01

    Explanation of Cold Fusion [1] ``It is k-capture forming dineutrons followed by absorption by palladium.'' with excess heat energy no more than about .15 MeV per nucleon. Experimentally [1], ^1H and electrons are at high pressure at the center of a palladium wire sample, ``After hours of loading with ^1H, bubbles were present on the wire surface and the wire's resistance had stopped increasing, there was a fizz of hydrogen from the wire within a few seconds after loading current and large bubbles were stopped.'' a repeatable cycle. K-capture rate is affected by environment at the 1/10000 level has has been known since 1946 ( ref. [6]in [1]); and recently has been seen at the 0.35% level for 7Be in C60 [2]. Neutron halos have been seen recently in 8He [3], 6He [4] and others long ago. Conclusions: 1) the evidence for dineutrons is fairly good and as in all K-captures is accompanied by a neutrino emission. collapse of a star to a neutron star has a succession of K-captures in conditions like cold fusion i.e. high pressure. 2)Dark matter is dineutrons from formation of neutron stars and black holes, and dark energy of neutrinos generated in neutron stars, ordinary stars and black holes. If in the latter, then their mass must be zero for an infinite horizon. References: [1] M. Levi, DAMOP Meeting poster paper, session WP, 16-19 May,1995 [2]T. Ohtsuku et al., Phys. Rev. Lett. 98, 252501 (2007) [3] V. I. Ryjkov et al., Phys. Rev. Lett. 101, 01901 (2008) [4] L. B. Wang et al., Phys. Rev. Lett. 93 ,142501 (2004).

  11. {alpha}-condensed state with a core nucleus

    SciTech Connect

    Itagaki, N.; Kimura, M.; Kurokawa, C.; Ito, M.; Oertzen, W. von

    2007-03-15

    We demonstrate based on a microscopic {alpha}-cluster model that {alpha}-condensed states appear not only in light nuclei such as {sup 12}C and {sup 16}O but also in heavier nuclei with a core at excitation energies corresponding to multi-{alpha}-threshold energies. To extend the study of normal {alpha}-condensed state to the cases of heavier nuclei with an inner strongly bound core ({sup 16}O) and also to non-4N-nuclei (e.g., 2{alpha}+dineutron), we introduce a Monte Carlo technique for the description of the Schuck wave function, which are called ''virtual Schuck'' wave function.

  12. Neutron correlations in the decay of the first excited state of 11Li

    NASA Astrophysics Data System (ADS)

    Smith, J. K.; Baumann, T.; Bazin, D.; Brown, J.; DeYoung, P. A.; Frank, N.; Jones, M. D.; Kohley, Z.; Luther, B.; Marks, B.; Spyrou, A.; Stephenson, S. L.; Thoennessen, M.; Volya, A.

    2016-11-01

    The decay of unbound excited 11Li was measured after being populated by a two-proton removal from a 13B beam at 71 MeV/nucleon. Decay energy spectra and Jacobi plots were obtained from measurements of the momentum vectors of the 9Li fragment and neutrons. A resonance at an excitation energy of ∼1.2 MeV was observed. The kinematics of the decay are equally well fit by a simple dineutron-like model or a phase-space model that includes final state interactions. A sequential decay model can be excluded.

  13. Cold dilute neutron matter on the lattice. II. Results in the unitary limit

    SciTech Connect

    Lee, Dean; Schaefer, Thomas

    2006-01-15

    This is the second of two articles that investigate cold dilute neutron matter on the lattice using pionless effective field theory. In the unitary limit, where the effective range is zero and scattering length is infinite, simple scaling relations relate thermodynamic functions at different temperatures. When the second virial coefficient is properly tuned, we find that the lattice results obey these scaling relations. We compute the energy per particle, pressure, spin susceptibility, dineutron correlation function, and an upper bound for the superfluid critical temperature.

  14. Higher-order dynamical effects in Coulomb dissociation

    SciTech Connect

    Esbensen, H.; Bertsch, G.F.; Bertulani, C.A.

    1995-08-01

    Coulomb dissociation is a technique commonly used to extract the dipole response of nuclei far from stability. This technique is applicable if the dissociation is dominated by dipole transitions and if first-order perturbation theory is valid. In order to assess the significance of higher-order processes we solve numerically the time evolution of the wave function for a two-body breakup in the Coulomb field from a high Z target. We applied this method to the breakup reactions: {sup 11}Be {yields} {sup 10}Be + n and {sup 11}Li {yields} +2n. The latter is treated as a two-body breakup, using a di-neutron model.

  15. Light Nuclei and HyperNuclei from Quantum Chromodynamics in the Limit of SU(3) Flavor Symmetry

    SciTech Connect

    Beane, S R; Cohen, S D; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Walker-Loud, A

    2013-02-01

    The binding energies of a range of nuclei and hypernuclei with atomic number A <= 4 and strangeness |s| <= 2, including the deuteron, di-neutron, H-dibaryon, {sup 3}He, {sub {Lambda}}{sup 3}He, {sub {Lambda}}{sup 4}He, and {sub {Lambda}{Lambda}}{sup 4}He, are calculated in the limit of flavor-SU(3) symmetry at the physical strange quark mass with quantum chromodynamics (without electromagnetic interactions). The nuclear states are extracted from Lattice QCD calculations performed with n{sub f}=3 dynamical light quarks using an isotropic clover discretization of the quark-action in three lattice volumes of spatial extent L ~ 3.4 fm, 4.5 fm and 6.7 fm, and with a single lattice spacing b ~ 0.145 fm.

  16. Structure of the spatial periphery of the isotopes {sup 9,11}Li

    SciTech Connect

    Galanina, L. I. Zelenskaya, N. S.

    2015-07-15

    The cross sections for the (t, p) reactions on the lithium isotopes {sup 9,11}Li were calculated within a theoretical approach based on employing integral equations of the four-body problem in the Alt—Grassberger-Sandhas formalism and the multiparticle shell model. This made it possible to determine the wave functions for the relative motion of various clusters and the nuclear core and to calculate, on their basis, the root-mean-square radii of nuclei of the isotopes {sup 9,11}Li and the spatial structure of their neutron periphery. It is shown that the {sup 9}Li nucleus has virtually no neutron halo. The {sup 11}Li nucleus is a Borromean halo nucleus. The two-neutron periphery of this nucleus manifests itself in both spatial configurations, a dineutron and a cigar one, the respective root-mean-square radii being large (about 6.5 to 6.9 fm)

  17. Two-neutron decay of excited states of 11Li

    NASA Astrophysics Data System (ADS)

    Smith, Jenna; MoNA Collaboration

    2013-10-01

    One prominent example of a Borromean nucleus is the two-neutron halo nucleus, 11Li. All excited states of this nucleus are unbound to two-neutron decay. Many theories propose that the two valence neutrons exhibit dineutron behavior in the ground state, but it is unclear what effect such a structure would have on the decay of the excited states. We have recently completed an experiment designed to study the decay of one of these excited states. Unbound 11Li was populated via a two-proton knockout from 13B. The two emitted neutrons were detected with the Modular Neutron Array (MoNA) and the Large-area multi-Institutional Scintillator Array (LISA) in coincidence with the daughter fragment, 9Li. Preliminary results will be discussed.

  18. Recent results from MoNA-LISA

    NASA Astrophysics Data System (ADS)

    Spyrou, Artemisia

    2012-03-01

    Studies of the nuclear properties of nuclei close and even beyond the limits of stability have revealed exotic modes of decay and new structural characteristics. The MoNA-LISA array is used at the National Superconducting Cyclotron Laboratory at Michigan State University to study nuclei along the neutron dripline. In a typical experiment, a radioactive beam is employed to produce the neutron-unbound state of interest. This state/resonance immediately decay into a neutron, which is detected by MoNA-LISA and a remaining charged nucleus detected by the sweeper magnet detector suite. In this talk, new exciting findings from recent MoNA-LISA experiments will be presented. These include the first observation of a dineutron decay from ^16Be, the exploration of the ``south shore'' of the Island of Inversion and the first evidence of the decay of the troubling nucleus ^26O.

  19. Investigation of the reaction d + d → {sup 2}He + {sup 2}n at the deuteron energy of 15 MeV

    SciTech Connect

    Konobeevski, E. S. Zuyev, S. V.; Kasparov, A. A.; Lebedev, V. M.; Mordovskoy, M. V.; Spassky, A. V.

    2015-07-15

    An experimental setup for studying the reaction d + d → {sup 2}He + {sup 2}n is described, and the first preliminary results of measurements at a deuteron energy of 15 MeV are presented. The experiment was aimed at determining the energies of quasibound singlet states of two-nucleon systems (nn and pp), these energies being important features of nucleon–nucleon (NN) interaction. The measurements in question were performed at a deuteron beamfrom the U-120 cyclotron of the Skobeltsyn Institute ofNuclear Physics (Moscow State University). Two protons and one of the neutrons fromthe breakup of the dineutron system were detected in the experiment. A simulation of the reaction in question and preliminary experimental results reveal the possibility of determining the energy of quasibound singlet states on the basis of the form of the energy spectra of particles originating from their breakup.

  20. Estimation of the Breakup Cross-Sections in 6He + 12C Reaction Within High-Energy Approximation and Microscopic Optical Potential

    NASA Astrophysics Data System (ADS)

    Lukyanov, V. K.; Zemlyanaya, E. V.; Lukyanov, K. V.

    The breakup cross-sections in the reaction 6He + 12C are calculated at about 40 MeV/nucleon using the high-energy approximation (HEA) and with the help of microscopic optical potentials (OP) of interaction with the target nucleus 12C of the projectile nucleus fragments 4He and 2n. Considering the di-neutron h = 2n as a single particle the relative motion hα wave function is estimated so that to explain both the separation energy of h in 6He and the rms radius of the latter. The stripping and absorbtion total cross-sections are calculated and their sum is compared with the total reaction cross-section obtained within a double-folding microscopic OP for the 6He + 12C scattering. It is concluded that the breakup cross-sections contribute to about 50% of the total reaction cross-section.

  1. Experiments of one-point cold fusion

    SciTech Connect

    Matsumoto, Takaaki )

    1993-11-01

    Experiments of one-point cold fusion have been performed by electrical discharging in ordinary and heavy water mixed with 0.6 mol/l potassium carbonate. A platinum pin anode was located perpendicular to a copper plate cathode. After discharge, the surfaces of the copper plates were examined by an optical microscope. Many ring spots caused by gravity decay of single and di-neutrons were separately distributed on the plates. Furthermore, several kinds of traces that might be produced by itonic hydrogen clusters and by tiny black and white holes were observed. The mechanisms of cold fusion by electrical discharge are also discussed in terms of the Nattoh model. 13 refs., 12 figs.

  2. 1n and 2n transfer with the Borromean nucleus 6He near the Coulomb barrier.

    PubMed

    Chatterjee, A; Navin, A; Shrivastava, A; Bhattacharyya, S; Rejmund, M; Keeley, N; Nanal, V; Nyberg, J; Pillay, R G; Ramachandran, K; Stefan, I; Bazin, D; Beaumel, D; Blumenfeld, Y; de France, G; Gupta, D; Labiche, M; Lemasson, A; Lemmon, R; Raabe, R; Scarpaci, J A; Simenel, C; Timis, C

    2008-07-18

    Angular distributions for 1n and 2n transfer are reported for the 6He+65Cu system at E_{lab}=22.6 MeV. For the first time, triple coincidences between alpha particles, neutrons, and characteristic gamma rays from the targetlike residues were used to separate the contributions arising from 1n and 2n transfer. The differential cross sections for these channels, elastic scattering, and fusion were analyzed using a coupled reaction channels approach. The large measured ratio of the 2n-to-1n cross section and the strong influence of 2n transfer on other channels indicate that the dineutron configuration of 6He plays a dominant role in the reaction mechanism.

  3. Nuclear Sturcture Along the Neutron Dripline: MoNa-LISA and the dinueutron system

    SciTech Connect

    Spyou, Artemis

    2012-09-05

    Nuclei with extreme neutron-to-proton ratios were found to present different structures from what was known for the stable ones. With the current facilities we can now study nuclei that lie even beyond the neutron drip line. At the National Superconducting Cyclotron Laboratory at Michigan State University we use the MoNA/Sweeper setup to perform such studies of neutron unbound nuclei. In a typical experiment, a radioactive beam is employed to produce the nucleus of interest. This unbound nucleus immediately decays into a neutron and a remaining charged fragment, both of which are detected and used to reconstruct the original nucleus and study its properties. In this Colloquium, new exciting findings from recent experiments will be presented. These include the first observation of a dineutron decay from 16Be, the exploration of the “south shore” of the Island of Inversion and the first evidence of the decay of the troubling nucleus 26O.

  4. Analytical potential for the elastic scattering of light halo nuclei below and close to the Coulomb barrier

    SciTech Connect

    Borowska, L.; Terenetsky, K.; Verbitsky, V.; Fritzsche, S.

    2009-04-15

    An analytical expression for the dynamic polarization potential is derived for the elastic scattering of light halo nuclei in the Coulomb field of heavy targets. The derivation is based on the adiabatic motion of the projectile below and close to the Coulomb barrier together with a uniform approximation for the Coulomb functions. Detailed computations have been carried out for the elastic scattering of d+{sup 208}Pb and {sup 6}He+{sup 208}Pb at collision energies of 8 and 17.8 MeV and are compared with measurements as far as available. The obtained expression for the dynamic polarization potential is simple and can be applied for any arbitrary system with a dineutron configuration.

  5. Distorted-wave Born approximation study of the 11Li(p,t)9Li reaction

    NASA Astrophysics Data System (ADS)

    Cowley, A. A.

    2016-06-01

    The reaction 11Li(p,t)9Li(gs) at an incident energy of 4 MeV is treated in terms of a simplistic distorted-wave Born approximation transfer. The halo neutrons involved in the reaction are treated as a di-neutron cluster transferred in a simultaneous process. This appears to be a good approximation of the mechanism. The dominant contribution to the reaction comes from the known (1s 1/2)2 structure component of the ground state of 11Li, and the cross section angular distribution seems to be relatively insensitive to the fact that 11 Li has an anomalously large radius due to its Borromean halo properties. Significantly this simple treatment of the reaction is in much better agreement with the experimental angular distribution than a more sophisticated calculation.

  6. Analysis of elastic scattering and breakup of {sup 11}li in collisions with protons using a dynamical two-cluster model

    SciTech Connect

    Lukyanov, V. K. Zemlyanaya, E. V.; Lukyanov, K. V.

    2015-01-15

    The {sup 11}Li scattering and breakup on protons is considered under the assumption that the {sup 11}Li nucleus consists of two interacting clusters, which are a c = {sup 9}Li core and a h = 2n dineutron halo. The single-particle density of the {sup 11}Li nucleus, amicroscopic optical potential, and the cross section for {sup 11}Li+p scattering for various choices of cluster shape are obtained and analyzed by folding the density distribution for either cluster with the probability density for the relative motion of two clusters. A comparison with experimental data of the scattering cross section at low, 60–75 MeV, and intermediate, 700 MeV, energies is performed. The momentum distribution of c fragments upon {sup 11}Li breakup is calculated and studied with a help of the obtained p + c and p + h microscopic optical potentials.

  7. Bound and unbound nuclear systems at the drip lines: a one-dimensional model

    NASA Astrophysics Data System (ADS)

    Moschini, L.; Pérez-Bernal, F.; Vitturi, A.

    2016-08-01

    We construct a one-dimensional toy model to describe the main features of Borromean nuclei at the continuum threshold. The model consists of a core and two valence neutrons, unbound in the mean potential, that are bound by a residual point contact density-dependent interaction. Different discretization procedures are used (harmonic oscillator and transformed harmonic oscillator bases, or use of large rigid wall box). Resulting energies and wave functions, as well as inelastic transition intensities, are compared within the different discretization techniques, as well as with the exact results in the case of one particle and with the results of the di-neutron cluster model in the two particles case. Despite its simplicity, this model includes the main physical features of the structure of Borromean nuclei in an intuitive and computationally affordable framework, and will be extended to direct reaction calculations.

  8. Muon capture on the deuteron and the neutron-neutron scattering length

    NASA Astrophysics Data System (ADS)

    Marcucci, L. E.; Machleidt, R.

    2014-11-01

    Background: We consider the muon capture reaction μ-+2H→νμ+n +n , which presents a "clean" two-neutron (n n ) system in the final state. We study here its capture rate in the doublet hyperfine initial state (ΓD). The total capture rate for the muon capture μ-+3He→νμ+3H (Γ0) is also analyzed, although, in this case, the n n system is not so clean anymore. Purpose: We investigate whether ΓD (and Γ0) could be sensitive to the n n S -wave scattering length (an n), and we check on the possibility to extract an n from an accurate measurement of ΓD. Method: The muon capture reactions are studied with nuclear potentials and charge-changing weak currents, derived within chiral effective field theory. The next-to-next-to-next-to-leading-order chiral potential with cutoff parameter Λ =500 MeV is used, but the low-energy constant (LEC) determining an n is varied so as to obtain an n=-18.95 ,-16.0 ,-22.0 , and +18.22 fm. The first value is the present empirical one, while the last one is chosen such as to lead to a di-neutron bound system with a binding energy of 139 keV. The LEC's cD and cE, present in the three-nucleon potential and axial-vector current (cD), are constrained to reproduce the A =3 binding energies and the triton Gamow-Teller matrix element. Results: The capture rate ΓD is found to be 399 (3 ) s-1 for an n=-18.95 and -16.0 fm; and 400 (3 ) s-1 for an n=-22.0 fm. However, in the case of an n=+18.22 fm, the result of 275 (3 ) s-1 [ 135 (3 ) s-1 ] is obtained, when the di-neutron system in the final state is unbound (bound). The total capture rate Γ0 for muon capture on 3He is found to be 1494(15), 1491(16), 1488(18), and 1475(16) s-1 for an n=-18.95 ,-16.0 ,-22.0 , and +18.22 fm, respectively. All the theoretical uncertainties are due to the fitting procedure and radiative corrections. Conclusions: Our results seem to exclude the possibility of constraining a negative an n with an uncertainty of less than ˜±3 fm through an accurate

  9. Mechanisms of sequential particle transfer and characteristics of light neutron-excess and oriented nuclei

    NASA Astrophysics Data System (ADS)

    Galanina, L. I.; Zelenskaya, N. S.

    2012-03-01

    The procedure for evaluating the second-order corrections to the matrix elements of the reaction A( x, y) B, which are obtained using the method of distorted waves with a finite radius of intercluster interaction (DWBAFR), is developed. It is based on the assumption of a virtual cluster structure of light nuclei and uses integral equations for a four-body problem in the Alt-Grassberger-Sandhas formalism. These corrections are related with the mechanisms of sequential particles transfer. The latter are represented by the quadrangle diagrams. Their matrix elements are summed up coherently with those given by the pole and triangle diagrams which were calculated by using DWBAFR. The computer code QUADRO is written for the numerical implementation of the method proposed. The statistical tensors of nucleus B formed in the reaction A( x, y) B at incident particle energies of about 10 MeV/nucleon in the center of mass frame are determined. Specific calculations allowed for description of both the experimental cross sections (0-rank statistical tensors) of various reactions (including those where nucleus B has some excess neutrons) and polarized characteristics of nucleus B* (in the case of the latter produced in the exited state). A two-neutron periphery of nuclei 6He, 10Be, 12B (both in dineutron and cigarlike configurations) is restored by analyzing the differential cross sections of elastic alpha-6He-scattering and 9Be( d, p)10Be and 10B( t, p)12B reactions. It is shown that the structure of neutron peripheries is fundamentally different for these nuclei and its feature depends on the way those neutron-excess nuclei are formed: in 6He both configurations contribute to a two-neutron halo, while in 10Be there is a barely noticeable one-neutron halo, and in 12B there is a "dineutron skin". Orientation characteristics of nuclei B* are calculated. Their comparison with experimental data made it possible to draw important conclusions about a contribution to the statistical

  10. Simulation of two neutron detection for invariant mass spectroscopy of unstable nuclei

    NASA Astrophysics Data System (ADS)

    Tsubota, Jyunichi; Samuraicommissioning Collaboration

    2014-09-01

    Two neutron detection in invariant mass spectroscopy is essential to study neutron rich nuclei near and beyond neutron drip line. Recently, Coulomb breakup measurements of 19B and 22C, and study of the unbound nucleus 26O were performed at RIBF. Goal of the Coulomb breakup measurements is to study di-neutron like correlation, while 26O is interesting as a candidate of two neutron radioactivity. In these measurements, decay products, 24O and two neutrons from 26O, for example, are detected in coincidence by SAMURAI spectrometer. The neutrons are detected by large acceptance plastic scintillator array NEBULA. If a neutron scatters twice or more, this may cause a fake signal (crosstalk), and become a background. The crosstalk background can be eliminated by causality cut using time, position, pulse height information. The cut condition is investigated by a Monte-Carlo simulation based on the Geant4 tool kit to obtain high detection efficiency with small crosstalk background. The simulation is compared with experimental data of quasi-monoenergetic neutrons at 200 MeV and 250 MeV produced in the 7Li(p,n)7Be(g.s. + 0.43 MeV) reaction. A new algorithm of crosstalk cut will also be discussed.

  11. Two nucleon systems at mπ~450MeV from lattice QCD

    SciTech Connect

    Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Beane, Silas R.; Chang, Emmanuel; Detmold, William

    2015-12-23

    Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass of $m_\\pi\\sim 450~{\\rm MeV}$ in three spatial volumes using $n_f=2+1$ flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be $B_d = 14.4^{+3.2}_{-2.6} ~{\\rm MeV}$, while the dineutron is bound by $B_{nn} = 12.5^{+3.0}_{-5.0}~{\\rm MeV}$. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the 1S0 and 3S1-3D1 channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent with phenomenological nucleon-nucleon interactions. In both channels, the phase shifts are determined at three energies that lie within the radius of convergence of the effective range expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. Thus, the extracted phase shifts allow for matching to nuclear effective field theories, from which low energy counterterms are extracted and issues of convergence are investigated. As part of the analysis, a detailed investigation of the single hadron sector is performed, enabling a precise determination of the violation of the Gell-Mann–Okubo mass relation.

  12. Two nucleon systems at mπ~450MeV from lattice QCD

    DOE PAGES

    Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; ...

    2015-12-23

    Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass ofmore » $$m_\\pi\\sim 450~{\\rm MeV}$$ in three spatial volumes using $$n_f=2+1$$ flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be $$B_d = 14.4^{+3.2}_{-2.6} ~{\\rm MeV}$$, while the dineutron is bound by $$B_{nn} = 12.5^{+3.0}_{-5.0}~{\\rm MeV}$$. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the 1S0 and 3S1-3D1 channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent with phenomenological nucleon-nucleon interactions. In both channels, the phase shifts are determined at three energies that lie within the radius of convergence of the effective range expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. Thus, the extracted phase shifts allow for matching to nuclear effective field theories, from which low energy counterterms are extracted and issues of convergence are investigated. As part of the analysis, a detailed investigation of the single hadron sector is performed, enabling a precise determination of the violation of the Gell-Mann–Okubo mass relation.« less

  13. Changes in the structure of nuclei between the magic neutron numbers 50 and 82 as indicated by a rotating-cluster analysis of the energy values of the first 2j excited states of isotopes of cadmium

    SciTech Connect

    Pauling, L.

    1981-09-01

    Values of R, the radius of rotation of the rotating cluster, are calculated from the observed values of the energy of the lowest 2/sup +/ states of the even isotopes of Cd, Sn, and Te with the assumption that the cluster is ..cap alpha.., pb, and ..cap alpha.., respectively. R shows a maximum at approx. N = 58, a minimum at approx. N = 62, and a second maximum at approx. N = 70. The increase to the first maximum is interpreted as resulting from the overcrowding of spherons (alphas and tritons) in the mantle (outer layer) of the nuclei, causing the cluster to change from rotating in the mantle to skimming over its surface; the decrease to the minimum results from the addition of three dineutrons to the core, expanding the mantle and permitting the rotating cluster to begin to drop back into it; and the increase to the second maximum results from the overcrowding of the larger mantle surrounding the core containing the semimagic number 14 of neutrons rather than the magic numbers 8 for N = 50. The decrease after the second maximum results from the further increase in the number of core neutrons to 20, corresponding to the magic number 82. Some additional evidence for the change to an intermediate structure between N = 50 and N = 82 is also discussed.

  14. Three-body model for the two-neutron emission of Be16 [Three-body model for the two-neutron decay of 16Be

    DOE PAGES

    Lovell, A. E.; Nunes, F. M.; Thompson, I. J.

    2017-03-10

    While diproton emission was first theorized in 1960 and first measured in 2002, it was first observed only in 2012. The measurement of 14Be in coincidence with two neutrons suggests that 16Be does decay through the simultaneous emission of two strongly correlated neutrons. In this study, we construct a full three-body model of 16Be (as 14Be + n + n) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Here, in order to describe the three-body system, effective n – 14Be potentials were constructed, constrained by the experimental information on 15Be.more » The hyperspherical R-matrix method was used to solve the three-body scattering problem, and the resonance energy of 16Be was extracted from a phase-shift analysis. As a result, in order to reproduce the experimental resonance energy of 16Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of 16Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. In conclusion, our results confirm a dineutron structure for 16Be, dependent on the internal structure of the subsystem 15Be.« less

  15. Existence of diproton-like particles in 3+1 lattice QCD with two flavors and strong coupling

    SciTech Connect

    Faria da Veiga, Paulo A.; O'Carroll, Michael; Neto, A. Francisco

    2011-02-01

    Starting from quarks, gluons, and their dynamics, we consider the existence of two-baryon bound states of total isospin I=1 in an imaginary-time formulation of a strongly coupled 3+1-dimensional SU(3){sub c} lattice QCD with two flavors and 4x4 spin matrices, defined using the Wilson action. For a small hopping parameter {kappa}>0 and a much smaller gauge coupling 0<{beta}<<{kappa}<<1 (heavy quarks and large glueball mass), using a ladder approximation to a lattice Bethe-Salpeter equation, diproton-like bound states are found in the I=1 isospin sector, with asymptotic masses -6ln{kappa} and binding energies of order {kappa}{sup 2}. By isospin symmetry, for each diproton there is also a dineutron bound state with the same mass and binding energy. The dominant two-baryon interaction is an energy-independent spatial range-one potential with an O({kappa}{sup 2}) strength. There is also an attraction arising from gauge field correlations associated with six overlapping bonds, but it is subdominant. The overall range-one potential results from a quark-antiquark exchange with no meson exchange interpretation (wrong spin indices). The repulsive or attractive nature of the interaction does depend on the isospin and spin of the two-baryon states. A novel representation in term of permanents is obtained for the spin, isospin interaction between the baryons, which is valid for any isospin sector.

  16. Ground-state properties of 5H from the 6He(d ,3He)5H reaction

    NASA Astrophysics Data System (ADS)

    Wuosmaa, A. H.; Bedoor, S.; Brown, K. W.; Buhro, W. W.; Chajecki, Z.; Charity, R. J.; Lynch, W. G.; Manfredi, J.; Marley, S. T.; McNeel, D. G.; Newton, A. S.; Shetty, D. V.; Showalter, R. H.; Sobotka, L. G.; Tsang, M. B.; Winkelbauer, J. R.; Wiringa, R. B.

    2017-01-01

    We have studied the ground state of the unbound, very neutron-rich isotope of hydrogen 5H, using the 6He(d ,3He )5H reaction in inverse kinematics at a bombarding energy of E (6He)=55 A MeV. The present results suggest a ground-state resonance energy ER=2.4 ±0.3 MeV above the 3H +2 n threshold, with an intrinsic width of Γ =5.3 ±0.4 MeV in the 5H system. Both the resonance energy and width are higher than those reported in some, but not all previous studies of 5H. The previously unreported 6He(d ,t )g.s.5He reaction is observed in the same measurement, providing a check on the understanding of the response of the apparatus. The data are compared to expectations from direct two-neutron and dineutron decay. The possibility of excited states of 5H populated in this reaction is discussed using different calculations of the 6He→5H +p spectroscopic overlaps from shell-model and ab initio nuclear-structure calculations.

  17. Two-neutron correlations in {sup 6}He in a Coulomb breakup reaction

    SciTech Connect

    Kikuchi, Yuma; Kato, Kiyoshi; Myo, Takayuki; Takashina, Masaaki; Ikeda, Kiyomi

    2010-04-15

    We investigate the three-body Coulomb breakup of a two-neutron halo nucleus, {sup 6}He. Based on the alpha+n+n model, the three-body scattering states of {sup 6}He are described by using the combined methods of the complex scaling and the Lippmann-Schwinger equation. We calculate the breakup cross section, the two-dimensional energy distributions, and the invariant mass spectra for the E1 transition of {sup 6}He. We discuss the relations between the structures in these strengths and the n-n and alpha-n correlations of {sup 6}He. It is found that the {sup 5}He resonance in the final states contributes to make a low-energy enhancement of the strength. The n-n final-state interaction also contributes to enhance the strength globally. However, the ground-state correlations of {sup 6}He, such as a dineutron, are difficult to recognize in the strength because of the dominant effect of the final-state interaction.

  18. Ground-state properties of H5 from the He6(d,He3)H5 reaction

    SciTech Connect

    Wuosmaa, A. H.; Bedoor, S.; Brown, K. W.; Buhro, W. W.; Chajecki, Z.; Charity, R. J.; Lynch, W. G.; Manfredi, J.; Marley, S. T.; McNeel, D. G.; Newton, A. S.; Shetty, D. V.; Showalter, R. H.; Sobotka, L. G.; Tsang, M. B.; Winkelbauer, J. R.; Wiringa, R. B.

    2017-01-01

    We have studied the ground state of the unbound, very neutron-rich isotope of hydrogen 5H, using the 6He(d,3He)5H reaction in inverse kinematics at a bombarding energy of E(6He)=55A MeV. The present results suggest a ground-state resonance energy ER=2.4±0.3 MeV above the 3H+2n threshold, with an intrinsic width of Γ=5.3±0.4 MeV in the 5H system. Both the resonance energy and width are higher than those reported in some, but not all previous studies of 5H. The previously unreported 6He(d,t)5Heg.s. reaction is observed in the same measurement, providing a check on the understanding of the response of the apparatus. The data are compared to expectations from direct two-neutron and dineutron decay. The possibility of excited states of 5H populated in this reaction is discussed using different calculations of the 6He→5H+p spectroscopic overlaps from shell-model and ab initio nuclear-structure calculations.

  19. Understanding {sup 6}He induced reactions at energies around the Coulomb barrier

    SciTech Connect

    Moro, A. M.; Arias, J. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Borge, M. J. G.; Escrig, D.; Tengblad, O.; Gomez-Camacho, J.; Rodriguez-Gallardo, M.

    2009-06-03

    Recent developments aimed to understand the observed features arising in the scattering of the Borromean nucleus {sup 6}He on heavy targets are discussed and compared with recent data for {sup 6}He+{sup 208}Pb measured at the RIB facility at Louvain-la-Neuve at energies around the Coulomb barrier. The analysis of the elastic scattering data in terms of the optical model, reveals the presence of a long range absorption mechanism, that manifests in the form of a large value of the imaginary diffuseness parameter. The elastic data have been also compared with three--body CDCC calculations, based on a di-neutron model of {sup 6}He, and four--body CDCC calculations, based on a more realistic three-body model of this nucleus. Finally, the angular and energy distribution of {alpha} particles emitted at backward angles are discussed and compared with different theoretical approaches. We find that these {alpha} particles are produced mainly by a two-neutron transfer mechanism to very excited states in the residual nucleus.

  20. Three-body model for the two-neutron emission of Be16 [Three-body model for the two-neutron decay of 16Be

    DOE PAGES

    Lovell, A. E.; Nunes, F. M.; Thompson, I. J.

    2017-03-10

    While diproton emission was first theorized in 1960 and first measured in 2002, it was first observed only in 2012. The measurement of 14Be in coincidence with two neutrons suggests that 16Be does decay through the simultaneous emission of two strongly correlated neutrons. In this study, we construct a full three-body model of 16Be (as 14Be + n + n) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Here, in order to describe the three-body system, effective n – 14Be potentials were constructed, constrained by the experimental information on 15Be.more » The hyperspherical R-matrix method was used to solve the three-body scattering problem, and the resonance energy of 16Be was extracted from a phase-shift analysis. As a result, in order to reproduce the experimental resonance energy of 16Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of 16Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. In conclusion, our results confirm a dineutron structure for 16Be, dependent on the internal structure of the subsystem 15Be.« less

  1. Invariant-mass spectroscopy of 10Li and 11Li

    NASA Astrophysics Data System (ADS)

    Zinser, M.; Humbert, F.; Nilsson, T.; Schwab, W.; Simon, H.; Aumann, T.; Borge, M. J. G.; Chulkov, L. V.; Cub, J.; Elze, Th. W.; Emling, H.; Geissel, H.; Guillemaud-Mueller, D.; Hansen, P. G.; Holzmann, R.; Irnich, H.; Jonson, B.; Kratz, J. V.; Kulessa, R.; Leifels, Y.; Lenske, H.; Magel, A.; Mueller, A. C.; Münzenberg, G.; Nickel, F.; Nyman, G.; Richter, A.; Riisager, K.; Scheidenberger, C.; Schrieder, G.; Stelzer, K.; Stroth, J.; Surowiec, A.; Tengblad, O.; Wajda, E.; Zude, E.

    1997-02-01

    Break-up of secondary 11Li ion beams (280 MeV/nucleon) on C and Pb targets into 9Li and neutrons is studied experimentally. Cross sections and neutron multiplicity distributions are obtained, characterizing different reaction mechanisms. Invariant-mass spectroscopy for 11Li and 10Li is performed. The E1 strength distribution, deduced from electromagnetic excitation of 11Li up to an excitation energy of 4 MeV comprises ˜8% of the Thomas-Reiche-Kuhn energy-weighted sumrule strength. Two low-lying resonance-like structures are observed for 10Li at decay energies of 0.21(5) and 0.62(10) MeV, the former one carrying 26(10)% of the strength and likely to be associated with an s-wave neutron decay. A strong di-neutron correlation in 11Li can be discarded. Calculations in a quasi-particle RPA approach are compared with the experimental results for 10Li and 11Li.

  2. Decay dynamics of the unbound 25O and 26O nuclei

    NASA Astrophysics Data System (ADS)

    Hagino, K.; Sagawa, H.

    2016-03-01

    We study the ground and excited resonance states of 26O with a three-body model of 24O+n +n taking into account the coupling to the continuum. To this end, we use the new experimental data for the invariant mass spectroscopy of the unbound 25O and 26O nuclei, and present an update of three-body model calculations for the two-neutron decay of the 26O nucleus. With the new model inputs determined with the ground-state decay of 26O, we discuss the dineutron correlations and a halo nature of this nucleus, as well as the structure of the excited states. For the energy of the 2+ state, we achieve an excellent agreement with the experimental data with this calculation. We show that the 2+ state consists predominantly of the (d3/2) 2 configuration, for which the pairing interaction between the valence neutrons slightly decreases its energy from the unperturbed one. We also discuss the structure of excited 0+ states of the 26O nucleus. In particular, we show the existence of an excited 0+ state at 3.38 MeV, which is mainly composed of the (f7/2) 2 configuration.

  3. Three-body model for the two-neutron emission of 16Be

    NASA Astrophysics Data System (ADS)

    Lovell, A. E.; Nunes, F. M.; Thompson, I. J.

    2017-03-01

    Background: While diproton emission was first theorized in 1960 and first measured in 2002, it was first observed only in 2012. The measurement of 14Be in coincidence with two neutrons suggests that 16Be does decay through the simultaneous emission of two strongly correlated neutrons. Purpose: In this work, we construct a full three-body model of 16Be (as 14Be+n +n ) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Method: In order to describe the three-body system, effective n -14Be potentials were constructed, constrained by the experimental information on 15Be. The hyperspherical R -matrix method was used to solve the three-body scattering problem, and the resonance energy of 16Be was extracted from a phase-shift analysis. Results: In order to reproduce the experimental resonance energy of 16Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of 16Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. Conclusions: Our results confirm a dineutron structure for 16Be, dependent on the internal structure of the subsystem 15Be.

  4. Spin-polarized neutron matter: Critical unpairing and BCS-BEC precursor

    NASA Astrophysics Data System (ADS)

    Stein, Martin; Sedrakian, Armen; Huang, Xu-Guang; Clark, John W.

    2016-01-01

    We obtain the critical magnetic field required for complete destruction of S -wave pairing in neutron matter, thereby setting limits on the pairing and superfluidity of neutrons in the crust and outer core of magnetars. We find that for fields B ≥1017 G the neutron fluid is nonsuperfluid—if weaker spin 1 superfluidity does not intervene—a result with profound consequences for the thermal, rotational, and oscillatory behavior of magnetars. Because the dineutron is not bound in vacuum, cold dilute neutron matter cannot exhibit a proper BCS-BEC crossover. Nevertheless, owing to the strongly resonant behavior of the n n interaction at low densities, neutron matter shows a precursor of the BEC state, as manifested in Cooper-pair correlation lengths being comparable to the interparticle distance. We make a systematic quantitative study of this type of BCS-BEC crossover in the presence of neutron fluid spin polarization induced by an ultrastrong magnetic field. We evaluate the Cooper-pair wave function, quasiparticle occupation numbers, and quasiparticle spectra for densities and temperatures spanning the BCS-BEC crossover region. The phase diagram of spin-polarized neutron matter is constructed and explored at different polarizations.

  5. Spectroscopy of neutron unbound states in 24O and 23N

    NASA Astrophysics Data System (ADS)

    Jones, Michael David

    Unbound states in 24O and 23N were populated from an 24O beam at 83.4 MeV/u via inelastic excitation and proton knockout on a liquid deuterium target. Using the MoNA-LISA-Sweeper setup, the decay of each nucleus could be fully reconstructed. The two-body decay energy of 23N exhibits two prominent peaks at E = 100 +/- 20 keV and E = 960 +/- 30 keV with respect to the neutron separation energy. However, due to the lack of gamma-ray detection, a definitive statement on the structure of 23N could not be made. Shell model calculations with the WBP and WBT interactions lead to several interpretations of the spectrum. Both a single state at 2.9 MeV in 23N, or two states at 2.9 MeV and 2.75 MeV are consistent with the shell model and data. In addition, a two-neutron unbound excited state of 24O, populated by (d,d'), was observed with a three-body excitation of E = 715 +/- 110 (stat) +/-45 (sys) keV, placing it at E = 7.65 +/- 0.2 MeV with respect to the ground state. Three-body correlations for the decay of 24O → 22O + 2n show clear evidence for a sequential decay through an intermediate state in 23O. Neither a di-neutron nor phase-space model were able to describe the observed correlations. This measurement constitutes the first observation of a two-neutron sequential decay through three-body energy and angular correlations, and provides valuable insight into few-body physics at the neutron dripline.

  6. Dependence of nuclear binding on hadronic mass variation

    SciTech Connect

    Flambaum, V. V.; Wiringa, R. B.

    2007-11-15

    We examine how the binding of light (A{<=}8) nuclei depends on possible variations of hadronic masses, including meson, nucleon, and nucleon-resonance masses. Small variations in hadronic masses may have occurred over time; the present results can help evaluate the consequences for big bang nucleosynthesis. Larger variations may be relevant to current attempts to extrapolate properties of nucleon-nucleon interactions from lattice QCD calculations. Results are presented as derivatives of the energy with respect to the different masses so they can be combined with different predictions of the hadronic mass-dependence on the underlying current-quark mass m{sub q}. As an example, we employ a particular set of relations obtained from a study of hadron masses and sigma terms based on Dyson-Schwinger equations and a Poincare-covariant Faddeev equation for confined quarks and diquarks. We find that nuclear binding decreases moderately rapidly as the quark mass increases, with the deuteron becoming unbound when the pion mass is increased by {approx}60% (corresponding to an increase in X{sub q}=m{sub q}/{lambda}{sub QCD} of 2.5). In the other direction, the dineutron becomes bound if the pion mass is decreased by {approx}15% (corresponding to a reduction of X{sub q} by {approx}30%). If we interpret the disagreement between big bang nucleosynthesis calculations and measurements to be the result of variation in X{sub q}, we obtain an estimate {delta}X{sub q}/X{sub q}=K{center_dot}(0.013{+-}0.002) where K{approx}1 (the expected accuracy in K is about a factor of 2). The result is dominated by {sup 7}Li data.

  7. Magnetic structure of light nuclei from lattice QCD

    SciTech Connect

    Chang, Emmanuel; Detmold, William; Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Tiburzi, Brian C.; Beane, Silas R.

    2015-12-09

    Lattice QCD with background magnetic fields is used to calculate the magnetic moments and magnetic polarizabilities of the nucleons and of light nuclei with $A\\le4$, along with the cross-section for the $M1$ transition $np\\rightarrow d\\gamma$, at the flavor SU(3)-symmetric point where the pion mass is $m_\\pi\\sim 806$ MeV. These magnetic properties are extracted from nucleon and nuclear energies in six uniform magnetic fields of varying strengths. The magnetic moments are presented in a recent Letter. For the charged states, the extraction of the polarizability requires careful treatment of Landau levels, which enter non-trivially in the method that is employed. The nucleon polarizabilities are found to be of similar magnitude to their physical values, with $\\beta_p=5.22(+0.66/-0.45)(0.23) \\times 10^{-4}$ fm$^3$ and $\\beta_n=1.253(+0.056/-0.067)(0.055) \\times 10^{-4}$ fm$^3$, exhibiting a significant isovector component. The dineutron is bound at these heavy quark masses and its magnetic polarizability, $\\beta_{nn}=1.872(+0.121/-0.113)(0.082) \\times 10^{-4}$ fm$^3$ differs significantly from twice that of the neutron. A linear combination of deuteron scalar and tensor polarizabilities is determined by the energies of the $j_z=\\pm 1$ deuteron states, and is found to be $\\beta_{d,\\pm 1}=4.4(+1.6/-1.5)(0.2) \\times 10^{-4}$ fm$^3$. The magnetic polarizabilities of the three-nucleon and four-nucleon systems are found to be positive and similar in size to those of the proton, $\\beta_{^{3}\\rm He}=5.4(+2.2/-2.1)(0.2) \\times 10^{-4}$ fm$^3$, $\\beta_{^{3}\\rm H}=2.6(1.7)(0.1) \\times 10^{-4}$ fm$^3$, $\\beta_{^{4}\\rm He}=3.4(+2.0/-1.9)(0.2) \\times 10^{-4}$ fm$^3$. Mixing between the $j_z=0$ deuteron state and the spin-singlet $np$ state induced by the background magnetic field is used to extract the short-distance two-nucleon counterterm, ${\\bar L}_1$, of the pionless effective theory for $NN$ systems (equivalent to the meson-exchange current

  8. Magnetic structure of light nuclei from lattice QCD

    DOE PAGES

    Chang, Emmanuel; Detmold, William; Orginos, Kostas; ...

    2015-12-09

    Lattice QCD with background magnetic fields is used to calculate the magnetic moments and magnetic polarizabilities of the nucleons and of light nuclei withmore » $$A\\le4$$, along with the cross-section for the $M1$ transition $$np\\rightarrow d\\gamma$$, at the flavor SU(3)-symmetric point where the pion mass is $$m_\\pi\\sim 806$$ MeV. These magnetic properties are extracted from nucleon and nuclear energies in six uniform magnetic fields of varying strengths. The magnetic moments are presented in a recent Letter. For the charged states, the extraction of the polarizability requires careful treatment of Landau levels, which enter non-trivially in the method that is employed. The nucleon polarizabilities are found to be of similar magnitude to their physical values, with $$\\beta_p=5.22(+0.66/-0.45)(0.23) \\times 10^{-4}$$ fm$^3$ and $$\\beta_n=1.253(+0.056/-0.067)(0.055) \\times 10^{-4}$$ fm$^3$, exhibiting a significant isovector component. The dineutron is bound at these heavy quark masses and its magnetic polarizability, $$\\beta_{nn}=1.872(+0.121/-0.113)(0.082) \\times 10^{-4}$$ fm$^3$ differs significantly from twice that of the neutron. A linear combination of deuteron scalar and tensor polarizabilities is determined by the energies of the $$j_z=\\pm 1$$ deuteron states, and is found to be $$\\beta_{d,\\pm 1}=4.4(+1.6/-1.5)(0.2) \\times 10^{-4}$$ fm$^3$. The magnetic polarizabilities of the three-nucleon and four-nucleon systems are found to be positive and similar in size to those of the proton, $$\\beta_{^{3}\\rm He}=5.4(+2.2/-2.1)(0.2) \\times 10^{-4}$$ fm$^3$, $$\\beta_{^{3}\\rm H}=2.6(1.7)(0.1) \\times 10^{-4}$$ fm$^3$, $$\\beta_{^{4}\\rm He}=3.4(+2.0/-1.9)(0.2) \\times 10^{-4}$$ fm$^3$. Mixing between the $$j_z=0$$ deuteron state and the spin-singlet $np$ state induced by the background magnetic field is used to extract the short-distance two-nucleon counterterm, $${\\bar L}_1$$, of the pionless effective theory for $NN$ systems (equivalent to the

  9. Physics of Unstable Nuclei

    NASA Astrophysics Data System (ADS)

    Khoa, Dao Tien; Egelhof, Peter; Gales, Sydney; Giai, Nguyen Van; Motobayashi, Tohru

    2008-04-01

    ]C([symbol], n)[symbol]O by the transfer reaction [symbol]C([symbol]Li, t)[symbol]O / F. Hammache et al. -- SPIRAL2 at GANIL: a world of leading ISOL facility for the physics of exotic nuclei / S. Gales -- Magnetic properties of light neutron-rich nuclei and shell evolution / T. Suzuki, T. Otsuka -- Multiple scattering effects in elastic and quasi free proton scattering from halo nuclei / R. Crespo et al. -- The dipole response of neutron halos and skins / T. Aumann -- Giant and pygmy resonances within axially-symmetric-deformed QRPA with the Gogny force / S. Péru, H. Goutte -- Soft K[symbol] = O+ modes unique to deformed neutron-rich unstable nuclei / K. Yoshida et al. -- Synthesis, decay properties, and identification of superheavy nuclei produced in [symbol]Ca-induced reactions / Yu. Ts. Oganessian et al. -- Highlights of the Brazilian RIB facility and its first results and hindrance of fusion cross section induced by [symbol]He / P. R. S. Gomes et al. -- Search for long fission times of super-heavy elements with Z = 114 / M. Morjean et al. -- Microscopic dynamics of shape coexistence phenomena around [symbol]Se and [symbol]Kr / N. Hinohara et al. -- [symbol]-cluster states and 4[symbol]-particle condensation in [symbol]O / Y. Funaki et al. -- Evolution of the N = 28 shell closure far from stability / O. Sorlin et al. -- Continuum QRPA approach and the surface di-neutron modes in nuclei near the neutron drip-line / M. Matsuo et al. -- Deformed relativistic Hartree-Bogoliubov model for exotic nuclei / S. G. Zhou et al. -- Two- and three-body correlations in three-body resonances and continuum states / K. Katō, K. Ikeda -- Pion- and Rho-Meson effects in relativistic Hartree-Fock and RPA / N. V. Giai et al. -- Study of the structure of neutron rich nuclei by using [symbol]-delayed neutron and gamma emission method / Y. Ye et al. -- Production of secondary radioactive [symbol] Na beam for the study of [symbol]Na([symbol], p)[symbol]Mg stellar reaction / D. N. Binh et al

  10. Condensed Matter Nuclear Science

    NASA Astrophysics Data System (ADS)

    Takahashi, Akito; Ota, Ken-Ichiro; Iwamura, Yashuhiro

    wave function near surface of palladium lattice / X. Z. Li ... [et al.]. Theoretical comparison between semi-classical and quantum tunneling effect / F. Frisone. New cooperative mechanisms of low-energy nuclear reactions using super low-energy external field / F. A. Gareev and I. E. Zhidkova. Polyneutron theory of transmutation / J. C. Fisher. The thermal conduction from the centers of the nuclear reactions in solids / K.-I. Tsuchiya. Four-body RST general nuclear wavefunctions and matrix elements / I. Chaudhary and P. L. Hagelstein. Study on formation of tetrahedral or octahedral symmetric condensation by hopping of alkali or alkaline-earth metal ion / H. Miura. Calculations of nuclear reactions probability in a crystal lattice of lanthanum deuteride / V. A. Kirkinskii and Yu. A. Novikov. Possible coupled electron and electron neutrino in nucleus and its physical catalysis effect on D-D cold fusion into helium in Pd / M. Fukuhara. Tunnel resonance of electron wave and force of fluctuation / M. Ban. Types of nuclear fusion in solids / N. Yabuuchi. Neutrino-dineutron reactions (low-energy nuclear reactions induced by D[symbol] gas permeation through Pd complexes - Y. Iwamura effect) / V. Muromtsev, V. Platonov and I. Savvatimova. An explanation of earthquakes by the blacklight process and hydrogen fusion / H. Yamamoto. Theoretical modeling of electron flow action on probability of nuclear fusion of deuterons / A. I. Goncharov and V. A. Kirkinskii.