Small and Large Diameter, Water-Table Observation Wells Compared

SHALLOW ground-water investigations usually involve the use of various sizes of perforated observation wells and/or sometimes batteries of piezometer tubes. Such equipment is used to determine the position of the water table, defined as the upper surface of the saturation zone and also the surface of atmospheric pressure (3, 4) 0 . The zone of saturation, however, often extends above the surface of atmospheric pressure a distance dependent primarily on the soil texture

Photoproduction of mesons off nuclei

Recent results for the photoproduction of mesons off nuclei are reviewed. These experiments have been performed for two major lines of research related to the properties of the strong interaction. The investigation of nucleon resonances requires light nuclei as targets for the extraction of the isospin composition of the electromagnetic excitations. This is done with quasi-free meson photoproduction off the bound neutron and supplemented with the measurement of coherent photoproduction reactions, serving as spin and/or isospin filters. Furthermore, photoproduction from light and heavy nuclei is a very efficient tool for the study of the interactions of mesons with nuclear matter and the in-medium properties of hadrons. Experiments are currently rapidly developing due to the combination of high quality tagged (and polarized) photon beams with state-of-the-art 4pi detectors and polarized targets