15268276
Zone determinant expansions for nuclear lattice simulations
We introduce a new approximation to nucleon matrix determinants that is physically motivated by chiral effective theory. The method involves breaking the lattice into spatial zones and expanding the determinant in powers of the boundary hopping parameter.
119868800
Ab initio lattice results for Fermi polarons in two and three dimensions
We investigate the attractive Fermi polaron problem in two and three dimensions using non-perturbative Monte Carlo simulations. We introduce a new Monte Carlo algorithm called the impurity lattice Monte Carlo method. This algorithm samples the path integral in a computationally efficient manner and has only small sign oscillations for systems with a single impurity. To benchmark the method, we calculate the universal polaron energy in three dimensions in the scale-invariant unitarity limit and find agreement with published results. We then present the first fully non-perturbative calculations of the polaron energy in two dimensions in the limit of zero range interactions. We find evidence for a smooth crossover transition from a fermionic quasiparticle to a molecular state as a function of interaction strength with significant mixing between the two descriptions in the crossover region.
13972554
A non-perturbative analysis of symmetry breaking in two-dimensional φ4 theory using periodic field methods
Abstract We describe the generalization of spherical field theory to other modal expansion methods. The main approach remains the same, to reduce a d -dimensional field theory into a set of coupled one-dimensional systems. The method we discuss here uses an expansion with respect to periodic-box modes. We apply the method to φ 4 theory in two dimensions and compute the critical coupling and critical exponents. We compare with lattice results and predictions via universality and the two-dimensional Ising model.
125749692
Nuclear lattice simulations
We review recent progress on nuclear lattice simulations using chiral effective field theory. We discuss lattice results for dilute neutron matter at next-to-leading order, three-body forces at next-to-next-to- leading order, isospin-breaking and Coulomb effects, and the binding energy of light nuclei.
15307965
The role of Monte Carlo within a diagonalization/Monte Carlo scheme
Abstract We review the method of stochastic error correction which eliminates the truncation error associated with any subspace diagonalization. Monte Carlo sampling is used to compute the contribution of the remaining basis vectors not included in the initial diagonalization. The method is part of a new approach to computational quantum physics which combines both diagonalization and Monte Carlo techniques.
118374917
Lattice calculations for A = 3 , 4, 6, 12 nuclei using chiral effective field theory
Abstract.We present lattice calculations for the ground-state energies of tritium, helium-3, helium-4, lithium-6, and carbon-12 nuclei. Our results were previously summarized in a letter publication. This paper provides full details of the calculations. We include isospin-breaking, Coulomb effects, and interactions up to next-to-next-to-leading order in chiral effective field theory.
123008932
The response of drift tubes to variations in wire diameter and gas filling
Abstract A systematic study of the response of single-wire drift tubes to variations in the wire diameter and gas fillings has been conducted. Gas gain as a function of applied voltage and pulse-shape characteristics were measured for both the proportional and streamer modes. Argon gas fillings with mixtures of ethane, methane, isobutane, and carbon dioxide were studied. Ethanol and isopropyl alcohol admixtures were added to determine effects on stability. Additional studies were conducted on nonstandard gas mixtures such as Freon and neon fillings, and “magic gas”. Wire diameters included in the study were 20, 25, 50, and 100 μm. The results demonstrate that streamer operation can be achieved with most gases and wire diameters. However, in most cases, admixtures of alcohol were necessary to obtain adequate streamer mode plateaus for the smaller diameter wires.
124265140
Low-energy neutron shielding
The attenuation of low-energy neutrons (< 20 MeV) through a 120-cm-thick slab shield of various mixtures of concrete, boron compounds, and water has been investigated. A Monte Carlo code was used to sample the neutron probability distribution and track the neutrons through the shield.
120631837
A bifilar helical multiware proportional chamber for position sensitive detection of minimum ionizing particles
Abstract A new type of multiware proportional chamber with a helical cathode for delay line readout has been developed and studied in detail. It gives cathode delay line pulses nearly as large as the anode pulses, and hence is well-suited for minimum ionizing particles. Measurements on such a chamber yielded spatial resolution better than 0.33 mm fwhm for 90 Sr β particles, a resolving time less than 30 ns, and maximum counting rate greater than 2 MHz. The most probable pulse height induced on the delay line by minimum ionizing particles in this chamber is approximately 8 mV.
110046760
The readout and DAQ system of the L3 silicon microstrip detector
Abstract In 1993 the L3 detector at LEP has been equipped with a Silicon Microstrip Detector (SMD). In this paper we give a full description of the various components of the SMD readout and DAQ system.
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.