The Atomic Lighthouse Effect

We investigate the deflection of light by a cold atomic cloud when the light-matter interaction is locally tuned via the Zeeman effect using magnetic field gradients. This "lighthouse" effect is strongest in the single-scattering regime, where deviation of the incident field is largest. For optically dense samples, the deviation is reduced by collective effects, as the increase in linewidth leads to a decrease of the magnetic field efficiency

Mirror-assisted coherent backscattering from the Mollow sidebands

In front of a mirror, the radiation of weakly driven large disordered clouds presents an interference fringe in the backward direction, on top of an incoherent background. Although strongly driven atoms usually present little coherent scattering, we here show that the mirror-assisted version can produce high contrast fringes, for arbitrarily high saturation parameters. The contrast of the fringes oscillates with the Rabi frequency of the atomic transition and the distance between the mirror and the atoms, due to the coherent interference between the carrier and the Mollow sidebands of the saturated resonant fluorescence spectrum emitted by the atoms. The setup thus represents a powerful platform to study the spectral properties of ensembles of correlated scatterers

Symmetrization and enhancement of the continuous Morlet transform

The forward and inverse wavelet transform using the continuous Morlet basis may be symmetrized by using an appropriate normalization factor. The loss of response due to wavelet truncation is addressed through a renormalization of the wavelet based on power. The spectral density has physical units which may be related to the squared amplitude of the signal, as do its margins the mean wavelet power and the integrated instant power, giving a quantitative estimate of the power density with temporal resolution. Deconvolution with the wavelet response matrix reduces the spectral leakage and produces an enhanced wavelet spectrum providing maximum resolution of the harmonic content of a signal. Applications to data analysis are discussed.Comment: 12 pages, 8 figures, 2 tables, minor revision, final versio

Calculation of Texas Lignite Resources Using the National Coal Resources Data System

Calculation of Texas lignite resources, according to U.S. Geological Survey (USGS) methodology, using the National Coal Resources Data System (NCRDS) and software, began in 1979 and is now complete with reporting here of resources in three new regions—Jackson-Yegua east, Jackson south, and Wilcox south. In these regions, site files containing well locations and total lignite thicknesses were created using Ingres, a relational database software. Resources were calculated using the Geographic Resources Analysis Support System (GRASS) GIS. Texas lignite resources were calculated from a database of 4,700 density and lithologic logs in terms of three USGS thickness categories (2.5 to 5 ft, >5 to 10 ft, and > 10 ft) and one Bureau of Economic Geology (BEG) category (≥3 ft). NCRDS resources, calculated using USGS methodology, total 46,979 million tons, of which 15,767 million tons (34 percent) are demonstrated resources. Most of them are in beds 2.5 to 5 ft thick. Two-thirds of the resources are in the Wilcox trend and one-third in the Jackson-Yegua trend. The state's richest lignite regions are Jackson-Yegua east and Wilcox east-central. In a comparison of NCRDS and BEG resource estimates, made using the same database and thickness category (≥3 ft), the USGS inflated inferred resources, whereas the BEG, using geologic models, constrained inferred resources and maximized demonstrated resources, which are 13,691 and 20,383 million tons, respectively. The USGS method is highly data dependent and can make no allowance for demonstrated resources as defined and estimated by the BEG with moderate certainty using geologic models. The computerized and geologic methods could be combined to improve resource estimates from limited data.Bureau of Economic Geolog

Texas lignite : near-surface and deep-basin resources

Figure 7 : Distribution of Central Texas Wilcox lignite. Figure 8 : Distribution of Southeast Texas Yegua lignite. Figure 9 : Distribution of Southeast Texas Jackson (Manning) lignite. Figure 13 : Distribution of South Texas Yegua - Jackson ligniteUT Librarie

Computerized Calcuation and Cahrarcterization of Lignite Resources in Texas

This project aimed to complete the calculation of lignite resources in Texas according to USGS Circular 891 and begin providing petrographic data on Texas lignite. To date, no resource calculations have been done; however, considerable petrographic data have been collected. There is no progress to report on the calculation of resources in the East Texas Jackson/Yegua trend because we are awaiting completion of data entry and digitization by the USGS. In July 1984, resource and lithologic data and geographical locations for data points in the East Texas Jackson/Yegua trend were submitted to the USGS, who is responsible for entering these data into the PR1ME computer database (TXSTRAT) and digitizing the geographical locations. At present, data have been entered for 23 of the 40 quadrangles submitted to the USGS (see attached figure). This represents 45 percent of the approximately 6,137 points submitted. Twenty-one of the 40 quadrangles have been digitized, representing 53 percent of the approximately 1,102 geographic locations submitted. Upon completion of data entry and digitization, we can begin the calculation of resources as outlined in our October 1985 proposal.Bureau of Economic Geolog

Cross-Formational Flow in the Palo Duro Basin, Texas Panhandle

Permian evaporite strata have been proposed as media for nuclear waste storage. Repository integrity is dependent on the extent of cross-formational flow, or leakage, through the Evaporite aquitard into the underlying Deep-Basin Brine aquifer. Pertinent data were reviewed and integrated to evaluate potential leakage. The Deep-Basin Brine aquifer is underpressured and has hydraulic heads hundreds of meters below those of the fresh-water Upper aquifer, indicating potential for downward flow between the Upper and Deep-Basin Brine aquifers. In the northwestern part of the basin, water in the Deep-Basin Brine aquifer has a meteoric isotopic signature, and its presence is cited as evidence for leakage from the Upper aquifer downward through the Evaporite aquitard. A plausible alternative source is lateral recharge from eastern New Mexico. Darcian leakage rates calculated from numerical models are very small (hundredths to thousandths of a μm/d) and depend primarily on the permeability of salt, which is stress dependent and overestimated in testing. If salt permeability is 10^-5 md, as measured recently in situ in competent New Mexico bedded salt, leakage through the Evaporite aquitard would be 6 x 10^-9 m/d and flow through an area of 25 km^2 (9 mi^2) approximately 0.15 m^3/d (40 gal/d). Though fractured, the Evaporite aquitard probably behaves regionally as an extremely low-permeability, low-flux porous medium. Basinal brines are compositionally stratified, ruling out substantial vertical mixing or mass transfer. Hydrologic isolation of the salt is further indicated by the inferred presence of Permian connate water in the aquitard, high bromide content of halite, and dominance of syndepositional and early diagenetic halite textures. Only the salt dissolution zone, atop the aquitard, has experienced post-Permian dissolution. Available geochemical and petrographic evidence shows that cross-formational flow, or leakage, through the Evaporite aquitard is very slight.Bureau of Economic Geolog

Evaluating the Geology and Ground Water Hydrology of Deep-Basin Lignite in Texas

Lignite resources in Texas are currently estimated at 58 billion short tons (755 quadrillion Btu's or Quads [Q]) of energy, constituting just over one-fourth or 26 percent of the State's energy endowment of 2,915 Q. Resources of near-surface lignite, those at depths between 20 and 200 feet (6.1 and 61 meters), are about 23 billion tons (300 Q), of which some 8.6 to 11.1 billion tons are exploitable by current surface mining methods. Near-surface reserves are adequate to meet the demand for lignite in this century. Meeting the demand in the next century and beyond will require the recovery of deep-basin lignite, occurring between depths of 200 and 2,000 feet (61 and 610 meters) below the surface. Resources of deep-basin lignite at these depths and in seams greater than 5 feet (1.5 meters) thick are about 35 billion tons (455 Q) or 16 percent of the State's energy endowment. These resources occur mainly in East Texas north of the Colorado River (about 70 percent) in two geologic units, primarily in the lower Eocene Wilcox Group (55 percent) and secondarily in the upper Eocene Jackson Group (15 percent).Bureau of Economic Geolog