123479705
Design and construction of double-sided silicon ladders for the L3 microvertex detector
Abstract The techniques used in the construction of the double-sided ladders for the L3 Silicon Microvertex Detector (SMD) are presented. The detector consists of two cylindrical layers, each of 12 ladders, with double-sided silicon detectors which provide r -phi and z coordinates measurements. This description includes ladder mechanical design and the assembly. A novel solution to readout the z -coordinates is presented. It optimizes very effectively the removal of heat generated by the readout electronics and minimizes the radiation length in the central region. Some results from the survey of the individual ladders are also discussed.
110905526
The GEM Silicon Tracking System
The GEM Collaboration has produced a baseline design for the GEM detector. The baseline design of the GEM Silicon Tracking System (STS) is discussed in this article. Mechanical and electrical engineering progress on the GEM STS is described. Results from simulations of detector performance and the implications on engineering issues are described.
89609083
Evidence for a New Phase of Solid He-3
)Permanent address: Faculte des Sciences, Orsay, France. See, for exaxnple, I. Prigogine, Non Equi/ibrinm Statistica/ Mechanics (Wiley, New York, 1962); P. Resibois, in-Many Pmticle Physics, edited by K. Meeron (Gordon and Breach, New York, 1966). J. Van der Waals, Dissertation, University of Leiden, 1873 (unpublished) . See M. Kac, G. Uhlenbeck, and P. Hemmer, J. Math. Phys. 4, 216, 229 (1963), and 5, 60 (1964); J. Lebowitz, G. Steli, and S. Baer, J. Math. Phys. (N.Y.) 4, 1282 (1965). See K. Kawasaki, Progr. Theor. Phys. 41, 1190 (1969), snd references quoted therein. ~H. Mori, Progr. Theor. Phys. 28, 763 (1962}. P. Resibois, J. Chem. Phys. 41, 2979 (1964). P. Resibois, J. Stat. Phys. 2, 21 (1970). J. Dorfman and E. Cohen, Phys. Rev. Lett. 25, 1257 (1970). L. Kadanoff and J. Swift, Phys. Rev. 166, 89 (1968). M. Ernst, E. Hauge, and J. Van Leeuwen, Phys. Rev. Lett. 25, 1254 (1970), and Phys. Rev. A 4, 2055 (1971). "B.Alder and T. Wainwright, Phys. Rev. A 1, 18 (1970); see also Refs. 8 and 10; and Y. Pomeau, to be published.
121875662
Correlated neutron-deuteron and neutron-triton emission after pion capture on 12C
Abstract Energy and angle measurements of neutron-deuteron and neutron-triton pairs emitted following negative-pion capture on 12 C have been made. Strong 180° correlation is observed in the angular distributions of both types of pairs, indicating substantial absorption by clusters in the 12 C nucleus.
110867317
Fail-safe ion chamber errant beam detector tailored for personnel protection
A description is given of a fail-safe ion chamber system designed to be part of the personnel safety system (PSS) for the Los Alamos Neutron Scattering Center (LANSCE) at the Los Alamos National Laboratory. It protects the occupants of experiment areas from large radiation doses caused by errant beam conditions during beam transport from the proton storage ring to the LANSCE neutron spallation target. The layered system consists of three types of highly reliable detector systems: a current limiter system located in the beam line, a neutron detector system located in experimental areas, and an ion chamber system located on the walls of the beam line tunnels. The ion chamber system is capable of shutting off the beam in less that 0.5 s, resulting in a worst-case personnel exposure of 0.005 Gys (0.5 rd).<<ETX>>
119883715
Negative pion capture on 12C with emission of neutron-proton pairs
Abstract Energy and angle measurements of neutron-proton pairs emitted after π − capture in 12 C have been made. The data are in partial agreement with several theories. Some evidence indicates that limits on the short-range correlation parameters might be determined from the nn/np ratio at backward angles.
2109187
Lattice effective field theory calculations for A = 3, 4, 6, 12 nuclei.
We present lattice results for the ground state energies of tritium, helium-3, helium-4, lithium-6, and carbon-12 nuclei. Our analysis includes isospin breaking, Coulomb effects, and interactions up to next-to-next-to-leading order in chiral effective field theory.
125682846
Nuclear Lattice simulations with Chiral Effective Field Theory
118940430
Temperature-dependent errors in nuclear lattice simulations
We study the temperature dependence of discretization errors in nuclear lattice simulations. We find that for systems with strong attractive interactions the predominant error arises from the breaking of Galilean invariance. We propose a local 'well-tempered' lattice action which eliminates much of this error. The well-tempered action can be readily implemented in lattice simulations for nuclear systems as well as cold atomic Fermi systems.
118573105
Effective Field Theory for Bound State Reflection
Abstract Elastic quantum bound-state reflection from a hard-wall boundary provides direct information regarding the structure and compressibility of quantum bound states. We discuss elastic quantum bound-state reflection and derive a general theory for elastic reflection of shallow dimers from hard-wall surfaces using effective field theory. We show that there is a small expansion parameter for analytic calculations of the reflection scattering length. We present a calculation up to second order in the effective Hamiltonian in one, two, and three dimensions. We also provide numerical lattice results for all three cases as a comparison with our effective field theory results. Finally, we provide an analysis of the compressibility of the alpha particle confined to a cubic lattice with vanishing Dirichlet boundaries.
18725629
Singularities of massless planar diagrams, large-N_c mesons in 3+1 dimensions, and the 't Hooft model
We study the singular Landau surfaces of planar diagrams contributing to scattering of a massless quark and antiquark in 3+1 dimensions. In particular, we look at singularities which remain after integration with respect to the various angular degrees of freedom. We derive a general relation between these singularities and the singularities of quark- antiquark scattering in 1+1 dimensions. We then classify all Landau surfaces of the 1+1 dimensional system. Combining these results, we deduce that the singular surfaces of the angle- integrated 3+1 dimensional amplitude must satisfy at least one of three conditions, which we call the planar light-cone conditions. We discuss the extension of our results to non-perturbative processes by means of the non-perturbative operator product expansion. Our findings offer new insights into the connection between the 't Hooft model and large-N_c mesons in 3+1 dimensions and may prove useful in studies of confinement in relativistic meson systems.