Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session H13: Structure and Reactions of Few-Nucleon Systems |
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Sponsoring Units: DNP GFB Chair: Judith McGover, University of Manchester Room: Plaza Court 2 |
Sunday, April 14, 2013 10:45AM - 10:57AM |
H13.00001: New precision era of strong interaction studies of the antikaon-nucleon interaction Johann Marton The antikaon interaction on nucleons and nuclei in the low-energy regime is a challenging research field in experiment as well as in theory. New precise data are available from x-ray spectroscopy of the lightest hadronic atoms with strangeness performed at DAFNE of LNF/INFN-Frascati by the SIDDHARAT International Collaboration. From the measurement of the x-ray transitions to low-lying levels the up-to-now most precise values for strong interaction parameters (hadronic shifts and widths) were extracted. The new precision data are crucial input for theory. The SIDDHARTA experimental method, the final results and the implications for our understanding of strong interaction with strangeness as well as future plans will be presented. [Preview Abstract] |
Sunday, April 14, 2013 10:57AM - 11:09AM |
H13.00002: Cross sections for neutron-deuteron elastic scattering in the energy range 135-250 MeV J.L. Matthews, M.B. Chtangeev, W.A. Franklin, T. Akdogan, E. Ertan, M.A. Kovash, M. Yuly New measurements are reported of the neutron-deuteron elastic scattering cross section at incident neutron energies from 135 to 250 MeV and center-of-mass angles from 80$^{\circ}$ to 130$^{\circ}$. Cross sections for neutron-proton elastic scattering were also measured with the same experimental setup for normalization purposes. The $nd$ cross section results are compared with predictions based on Faddeev calculations with and without the inclusion of three-nucleon forces (3NF), and with cross sections previously measured with charged particle and neutron beams at comparable energies. The effect of 3NF is clearly seen in the present work. The data at angles near the minimum in the cross section, where the 3NF contribution is most effective, are in excellent agreement at all energies with the theoretical predictions. [Preview Abstract] |
Sunday, April 14, 2013 11:09AM - 11:21AM |
H13.00003: Faddeev calculation for breakup neutron-deuteron scattering at 14.1 MeV lab energy Vladimir Suslov, Mikhail Braun, Igor Filikhin, Ivo Slaus, Branislav Vlahovic A new computational method for solving nucleon-deuteron breakup scattering problem has been applied to study inelastic neutron-deuteron scattering in the framework of configuration-space Faddeev-Noyes-Noble-Merkuriev equations. This method is based on the spline-decomposition in angular variable and on a generalization of the Numerov method for hyperradius. The Merkuriev-Gignoux-Laverne approach has been generalized for arbitrary nucleon-nucleon potentials and arbitrary number of partial waves. Neutron-deuteron observables at the incident nucleon energy 14.1 MeV have been calculated using the charge-independent Argonne AV14 nucleon-nucleon potential. Results have been compared with those of other authors and with experimental nucleon-deuteron scattering data. [Preview Abstract] |
Sunday, April 14, 2013 11:21AM - 11:33AM |
H13.00004: T-T Neutron Spectrum from Inertial Confinement Implosions Joseph Caggiano, Maria Gatu Johnson, Andrew Bacher, Denns McNabb Measurements of the T(2n,)$^4$He reaction (TT) have been conducted using high-purity tritium, gas-filled capsules in inertial confinement fusion (ICF) implosions. At the OMEGA laser facility, TT neutron spectra were measured using two instruments: the neutron-time-of-flight (nTOF) facility and the Magnetic Recoil Spectrometer (MRS) facility. The resolutions of these systems were improved for nTOF by using a crystal with much faster decay time and for MRS by using a thinner, more uniform CD2 recoil foil. Measurements at c.m. energies of 10-30 keV can be used to study the TT three-body reaction mechanism near astrophysical energies. With both nTOF and MRS, we observe a small, narrow peak starting at the 9.44 MeV endpoint, corresponding to the n + $^5$He (g.s.) reaction channel. Most of the TT reaction proceeds through other reaction channels which produce broad, continuous neutron spectra in the range 0 - 9.5 MeV. Implications for ICF experiments at the National Ignition Facility will be discussed. Work in collaboration with J. A. Frenje, D. T. Casey, M. J.-E. Manuel, N. Sinenian, A. B. Zylstra, F. H. Seguin, C. K. Li, R. D. Petrasso, V. Yu Glebov, P. B. Radha, D. D. Meyerhofer, T. C. Sangster, P. A. Amendt, R. Hatarik, D. B. Sayre, J. R. Rygg, H. W. Herrmann and Y. H. Kim. [Preview Abstract] |
Sunday, April 14, 2013 11:33AM - 11:45AM |
H13.00005: Three-body photodisintegration of $^3$He using a longitudinally polarized target and a circularly polarized $\gamma$ beam at 12.8 and 14.7 MeV Georgios Laskaris We report on the first measurement of the three-body photodisintegration of longitudinally polarized $^3$He using a circularly polarized $\gamma$-ray beam at incident photon energies 12.8 MeV and 14.7 MeV. The experiment was carried out at the High Intensity $\gamma$-ray Source facility located at the Triangle Universities Nuclear Laboratory.A high-pressure $^3$He target, polarized via spin exchange optical pumping with alkali metals, was employed. The neutrons from the three-body photo-disintegration were detected using ten liquid scintillators positioned in the reaction plane at five different angles between 75$^\circ$ and 165$^\circ$. Results on the spin-dependent double- and single- differential cross sections, the spin-dependent total cross sections, as well as the asymmetries will be presented and compared with the state-of-the-art three-body calculations for both energies. The first data points below pion production threshold of the three-body photodisintegration part of the GDH sum rule integrand will be also presented. Contributions from three-body photodisintegration at the photon energies of this work to the $^3$He GDH integrand below the pion production threshold will also be presented for the first time. [Preview Abstract] |
Sunday, April 14, 2013 11:45AM - 11:57AM |
H13.00006: \textit{Ab initio} many-body calculations of the $^4$He photo-absorption cross section Micah Schuster, Sofia Quaglioni, Calvin Johnson, Eric Jurgenson, Petr Navr\'{a}til Working within the no-core shell model approach with a similarity renormalization group (SRG) evolved two- and three-nucleon (NN+NNN) Hamiltonian, we compute the dipole strength function of $^4$He, using the Lorentz integral transform (LIT) method to obtain the continuum response. We then compute the total photo-absorption cross section of $^4$He. We pay particular attention to the convergence of the total strength and of the LIT of the dipole response as we increase the size of the harmonic oscillator basis. [Preview Abstract] |
Sunday, April 14, 2013 11:57AM - 12:09PM |
H13.00007: Solution of the Schroedinger Eq. in the presence of very long-range potentials George Rawitscher Conventional finite difference methods usually do not provide the required accuracy for the relative motion wave function of two colliding atoms or molecules for the large distances required in the presence of long range potentials at low temperatures. An alternative method is presented that obtains two independent solutions at large distances, that can be matched to the conventional solution at short distances. The method is akin to the Born approximation applied iteratively in the large distance domain, and hence by-passes the conventional methods of solving a differential equation. With this method, for a potential of the form C$_{6}$/r$^{6}$, 10 iterations suffice to achieve an accuracy of 10$^{-10}$ in the radial domain [100,1000]a$_{\mathrm{0}}$ for a wave number k $=$ 10$^{-3}$(a$_{0})^{\mathrm{-1}}$. For the case C$_{3}$/(r$^{3})$ convergence still takes place, but is not as fast, and requires a smaller radial domain. For example, an accuracy of 10$^{-8}$ is obtained after 19 iterations in the domain [2500,3000]a$_{0}$, with k $=$ 10$^{-3}$ (a$_{0})^{-1}$. [Preview Abstract] |
Sunday, April 14, 2013 12:09PM - 12:21PM |
H13.00008: Low-energy fusion caused by an interference Boris Ivlev Fusion of two deuterons of room temperature energy is discussed. The nuclei are in vacuum with no connection to any external source(electric or magnetic field, illumination, surrounding matter, traps, etc.) which may accelerate them. The energy of two nuclei is conserved and remains small during the motion through the Coulomb barrier. The penetration through this barrier, which is the main obstacle for low-energy fusion, strongly depends on a form of the incident flux on the Coulomb center at large distances from it. In contrast to the usual scattering, the incident wave is not a single plane wave but the certain superposition of plane waves of the same energy and various directions, for example, a conergent conical wave. The wave function close to the Coulomb center is determined by cusp caustic which is probed by de Broglie waves. The particle flux gets away from the cusp and moves to the Coulomb center providing a not small probability of fusion (cusp driven tunneling). Getting away from a caustic cusp also occurs in optics and acoustics. arXiv:1211.1243 [Preview Abstract] |
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