Low-energy electron transport with the method of discrete ordinates

The one-dimensional discrete ordinates code ANISN was adapted to transport low energy (a few MeV) electrons. Calculated results obtained with ANISN were compared with experimental data for transmitted electron energy and angular distribution data for electrons normally incident on aluminum slabs of various thicknesses. The calculated and experimental results are in good agreement for a thin slab (0.2 of the electron range), but not for the thicker slabs (0.6 of the electron range). Calculated results obtained with ANISN were also compared with results obtained using Monte Carlo methods

Equivalent flaw time-of-flight diffraction sizing with ultrasonic phased arrays

Ultrasonic phased array transducers can be used to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained. Traditional TOFD yields a single length parameter, while the equivalent flaw time-of-flight diffraction crack sizing method (EFTOFD) described here uses data from multiple look-angles to fit an equivalent degenerate ellipsoid to the crack. The size and orientation of the equivalent flaw can be used to estimate the actual crack size

Ultrasonic flaw sizing—An overview

The time-of-flight diffraction (TOFD) technique is one of the most common sizing methods in practical use by industry today. This method was developed over 40 years ago and is based on the technology and state of knowledge present at that time. A combination of phased arrays and equivalent flaw sizing methods are proposed as the foundation for a new generation of sizing methods that go beyond TOFD sizing

Design of Asymmetric 4π Shields for Space Reactors.

A one-dimensional shield optimization program based on the method of discrete ordinates has been developed and is used to determine material thicknesses used in asymmetric 4π shields for space power reactors. The two-dimensional discrete ordinates program DOT is used to check the design and the information generated in the DOT calculation is used as guide in shaping the shield which may be considered a first step in two-dimensional shield optimization

Specifications for the JASPER Program attenuation experiment

An integral shielding experiment has been designed to investigate neutron penetration through benchmark and representative mockups of the radial shield designs for advanced sodium-cooled reactor concepts. The experiment will be performed in FY 1986 at the ORNL Tower Shielding Facility to study neutron penetration through various combinations of graphite, boron carbide, and steel configurations using representative near-core and sodium-pool source spectra. Detailed configuration descriptions and measurement specifications for the experiment are included

Liquid Metal Reactor Program: JASPER USDOE/PNC Shielding Research Program: Technical progress report, August 1-September 30, 1986

This report details activities on the JASPER Shielding Program for the time period of August 1, 1986 through September 30, 1986. This report contains the measurements in phases VI and VII, a graphite benchmark study and an alternate loop type shield design study for the Liquid Metal Reactor (LMR), respectively. This report also includes the results of analyses for phases I, II, III, V, and VI

Resistivity peak values at transition between fractional quantum Hall states

Experimental data available in the literature for peak values of the diagonal resistivity in the transitions between fractional quantum Hall states are compared with the theoretical predictions. It is found that the majority of the peak values are close to the theoretical values for two-dimensional systems with moderate mobilities.Comment: 3 pages, 1 figur

Nuclear Anapole Moments

Nuclear anapole moments are parity-odd, time-reversal-even E1 moments of the electromagnetic current operator. Although the existence of this moment was recognized theoretically soon after the discovery of parity nonconservation (PNC), its experimental isolation was achieved only recently, when a new level of precision was reached in a measurement of the hyperfine dependence of atomic PNC in 133Cs. An important anapole moment bound in 205Tl also exists. In this paper, we present the details of the first calculation of these anapole moments in the framework commonly used in other studies of hadronic PNC, a meson exchange potential that includes long-range pion exchange and enough degrees of freedom to describe the five independent $S-P$ amplitudes induced by short-range interactions. The resulting contributions of pi-, rho-, and omega-exchange to the single-nucleon anapole moment, to parity admixtures in the nuclear ground state, and to PNC exchange currents are evaluated, using configuration-mixed shell-model wave functions. The experimental anapole moment constraints on the PNC meson-nucleon coupling constants are derived and compared with those from other tests of the hadronic weak interaction. While the bounds obtained from the anapole moment results are consistent with the broad ``reasonable ranges'' defined by theory, they are not in good agreement with the constraints from the other experiments. We explore possible explanations for the discrepancy and comment on the potential importance of new experiments.Comment: 53 pages; 10 figures; revtex; submitted to Phys Rev