Amphibious Seismic Survey Images Plate Interface at 1960 Chile Earthquake

The southern central Chilean margin at the site of the largest historically recorded earthquake in the Valdivia region, in 1960 (Mw = 9.5), is part of the 5000-km-long active subduction system whose geodynamic evolution is controversially debated and poorly understood. Covering the area between 36° and 40°S, the oceanic crust is segmented by prominent fracture zones. The offshore forearc and its onshore continuation show a complex image with segments of varying geophysical character, and several fault systems active during the past 24 m.y. In autumn 2001, the project SPOC was organized to study the Subduction Processes Off Chile, with a focus on the seismogenic coupling zone and the forearc. The acquired seismic data crossing the Chilean subduction system were gathered in a combined offshore-onshore survey and provide new insights into the lithospheric structure and evolution of active margins with insignificant frontal accretion

Lifetimes of heavy leptons and hadrons

Recent measurements of the lifetimes of the tau lepton and charm and beauty particles are reviewed, with emphasis on the experimental techniques used for vertex detection. 32 refs., 10 figs

CP violation in the B system: Physics at a high luminosity B Factory

CP Violation remains one of the unsolved puzzles in particle physics. Measurements of CP violating asymmetries in {beta} meson decay will test the Standard Model of electro-weak interactions and tell whether this phenomenon can be explained simply through the non-zero angles and phase in the CKM matrix. A high luminosity, energy asymmetric e{sup +}e{sup {minus}} storage ring provides the most versatile and best opportunity to measure CP violating effects and to test the consistency of the Standard Model, and should discrepancies occur, information will be available to establish the origin of CP violation outside the model. Such a machine is a very challenging, though technically achievable device, that when complemented with a suitable detector will represent a very exiting laboratory for studies of many aspects of beauty, charm, and {tau}{sup +-} physics in the coming decade. 26 refs., 11 figs., 5 tabs

Vertex detectors

The purpose of a vertex detector is to measure position and angles of charged particle tracks to sufficient precision so as to be able to separate tracks originating from decay vertices from those produced at the interaction vertex. Such measurements are interesting because they permit the detection of weakly decaying particles with lifetimes down to 10{sup {minus}13} s, among them the {tau} lepton and charm and beauty hadrons. These two lectures are intended to introduce the reader to the different techniques for the detection of secondary vertices that have been developed over the past decades. The first lecture includes a brief introduction to the methods used to detect secondary vertices and to estimate particle lifetimes. It describes the traditional technologies, based on photographic recording in emulsions and on film of bubble chambers, and introduces fast electronic registration of signals derived from scintillating fibers, drift chambers and gaseous micro-strip chambers. The second lecture is devoted to solid state detectors. It begins with a brief introduction into semiconductor devices, and then describes the application of large arrays of strip and pixel diodes for charged particle tracking. These lectures can only serve as an introduction the topic of vertex detectors. Time and space do not allow for an in-depth coverage of many of the interesting aspects of vertex detector design and operation

Results from the Mark II detector at SPEAR: SLAC-LBL collaboration

Recent results from the Mark II include measurements of the rho +- ..nu.. decay of the tau +- lepton, two-photon production of the eta'(958) meson, charmed meson decays, and the first observation of charmed baryons in e/sup +/e/sup -/ annihilation. 19 figures, 4 tables

Lifetimes of heavy flavour particles

Recent measurements of the lifetimes of charm and beauty particles are reviewed, with emphasis on the experimental techniques used for vertex detection. 44 refs., 9 figs., 3 tabs

“Sour gas” hydrothermal jarosite: ancient to modern acid-sulfate mineralization in the southern Rio Grande Rift

As many as 29 mining districts along the Rio Grande Rift in southern New Mexico contain Rio Grande Rift-type (RGR) deposits consisting of fluorite–barite±sulfide–jarosite, and additional RGR deposits occur to the south in the Basin and Range province near Chihuahua, Mexico. Jarosite occurs in many of these deposits as a late-stage hydrothermal mineral coprecipitated with fluorite, or in veinlets that crosscut barite. In these deposits, many of which are limestone-hosted, jarosite is followed by natrojarosite and is nested within silicified or argillized wallrock and a sequence of fluorite–barite±sulfide and late hematite–gypsum. These deposits range in age from ~10 to 0.4 Ma on the basis of 40Ar/39Ar dating of jarosite. There is a crude north–south distribution of ages, with older deposits concentrated toward the south. Recent deposits also occur in the south, but are confined to the central axis of the rift and are associated with modern geothermal systems. The duration of hydrothermal jarosite mineralization in one of the deposits was approximately 1.0 my. Most ?18OSO4–OH values indicate that jarosite precipitated between 80 and 240 °C, which is consistent with the range of filling temperatures of fluid inclusions in late fluorite throughout the rift, and in jarosite (180 °C) from Peña Blanca, Chihuahua, Mexico. These temperatures, along with mineral occurrence, require that the jarosite have had a hydrothermal origin in a shallow steam-heated environment wherein the low pH necessary for the precipitation of jarosite was achieved by the oxidation of H2S derived from deeper hydrothermal fluids. The jarosite also has high trace-element contents (notably As and F), and the jarosite parental fluids have calculated isotopic signatures similar to those of modern geothermal waters along the southern rift; isotopic ..