Contribution Of Shoots Research Articles

Tutorial: RTM image enhancement; bad models and mad physics

The final stage of a shot-based migration process is usually the imaging condition, which brings together elements of the upcoming and downgoing wavefield for each shot gather in order to form an image contribution. This procedure suffers limitations owing to the approximations made in representing the physics of the system, and in addition to that, the final summation of all shot contributions necessarily assumes that the subsurface parameter model was perfect, such that all image contributions align perfectly for summation (within a Fresnel zone), as well as ideally having recorded data that are noise free and adequately sampled. In this work, we assess the effect of unresolvable velocity error on the final image, and present a case study example of a technique for compensating for these errors via a localized phase alignment of each of the many thousands of elemental traces that can contribute to the final image.

Master equation approach of classical noise in intersubband detectors

Electronic transport in intersubband detectors is investigated theoretically and experimentally. Within the framework of inter--Wannier-Stark levels electron scattering, consistent dark current and low-frequency noise expressions are obtained through the resolution of the two first moments of a master equation for classical particles. In particular, the formulation of noise bridges over the vision of uncorrelated Johnson and shot contributions. Theoretical predictions are compared to measurements for five quantum well detectors, either photovoltaic or photoconductive, whose detection wavelength span from $8\phantom{\rule{0.222222em}{0ex}}\ensuremath{\mu}\text{m}$ to $17\phantom{\rule{0.222222em}{0ex}}\ensuremath{\mu}\text{m}$. Quantitative agreement with experiment is found for a broad range of biases and temperatures. Correlation effects are discussed and proven to either reduce or enhance the noise.