Search results for " X-ray imaging"
showing 10 items of 18 documents
Distribution, redox state and (bio)geochemical implications of arsenic in present day microbialites of Laguna Brava, Salar de Atacama
2018
Understanding how microorganisms adapted to the high arsenic concentration present on early Earth requires understanding of the processes involved in the arsenic biogeochemical cycle operating in living microbial mats. To this end, we investigated a living microbial mat from Laguna Brava (Salar de Atacama, Chile), a hypersaline lake with high arsenic concentration, using an array of conventional geochemical techniques, such as X-ray diffraction, SEM-EDX and Confocal Laser Scanning Microscopy (CLSM), combined with state-of-the-art high resolution scanning imaging techniques, including X-ray micro-fluorescence (μXRF) and X-ray Absorption Near Edge Structure (XANES) mapping. This experimental …
The NHXM observatory
2011
Exploration of the X-ray sky has established X-ray astronomy as a fundamental astrophysical discipline. While our knowledge of the sky below 10 keV has increased dramatically (∼8 orders of magnitude) by use of grazing incidence optics, we still await a similar improvement above 10 keV, where to date only collimated instruments have been used. Also ripe for exploration is the field of X-ray polarimetry, an unused fundamental tool to understand the physics and morphology of X-ray sources. Here we present a novel mission, the New Hard X-ray Mission (NHXM) that brings together for the first time simultaneous high-sensitivity, hard-X-ray imaging, broadband spectroscopy and polarimetry. NHXM will…
Geochemical evidence for arsenic cycling in living microbialites of a High Altitude Andean Lake (Laguna Diamante, Argentina)
2020
Arsenic is best known as an environmental toxin, but this element could also serve as a metabolic energy source to certain microorganisms. Moreover, As cycling may have driven microbial life on early Earth prior to oxygenation of the atmosphere. Still, little is known about the arsenic cycling processes occurring in the presence of microorganisms and the possible traces that could be preserved in the rock record. To advance our understanding of this we studied the geochemical proxies of microbial As metabolism in living microbialites from Laguna Diamante, a likely Precambrian ecosystem analogue (Catamarca, Argentina). In this study, we show that the coexistence of As(III) and As(V) strongly…
Thin-shell plastic lenses for space and laboratory applications
2004
We have identified an inexpensive, readily available, mechanically stable, extremely smooth, elastic, and mechanically uniform plastic suitable for thin film X-ray optics. Polyethylene terephthalate (PET) is easily deformed without losing its elastic properties or surface smoothness. Most important, PET can be coated with mono- or multilayers that reflect X-rays at grazing incidence. We have used these properties to produce X-ray optics made either as a concentric nest of cylinders or as a spiral. We have produced accurately formed shells in precisely machined vacuum mandresl or used a pin and wheel structure to form a continuously wound spiral. The wide range of medical, industrial and sci…
Room-temperature performance of 3 mm-thick cadmium-zinc-telluride pixel detectors with sub-millimetre pixelization.
2020
Cadmium–zinc–telluride (CZT) pixel detectors represent a consolidated choice for the development of room-temperature spectroscopic X-ray imagers, finding important applications in medical imaging, often as detection modules of a variety of new SPECT and CT systems. Detectors with 3–5 mm thicknesses are able to efficiently detect X-rays up to 140 keV giving reasonable room-temperature energy resolution. In this work, the room-temperature performance of 3 mm-thick CZT pixel detectors, recently developed at IMEM/CNR of Parma (Italy), is presented. Sub-millimetre detector arrays with pixel pitch less than 500 µm were fabricated. The detectors are characterized by good room-temperature performan…
Room-Temperature X-ray response of cadmium-zinc-Telluride pixel detectors grown by the vertical Bridgman technique
2020
In this work, the spectroscopic performances of new cadmium–zinc–telluride (CZT) pixel detectors recently developed at IMEM-CNR of Parma (Italy) are presented. Sub-millimetre arrays with pixel pitch less than 500 µm, based on boron oxide encapsulated vertical Bridgman grown CZT crystals, were fabricated. Excellent room-temperature performance characterizes the detectors even at high-bias-voltage operation (9000 V cm−1), with energy resolutions (FWHM) of 4% (0.9 keV), 1.7% (1 keV) and 1.3% (1.6 keV) at 22.1, 59.5 and 122.1 keV, respectively. Charge-sharing investigations were performed with both uncollimated and collimated synchrotron X-ray beams with particular attention to the mitigation o…
Lobster eye optics for nano-satellite x-ray monitor
2011
The Lobster eye design for a grazing incidence X-ray optics provides wide field of view of the order of many degrees, for this reason it would be a convenient approach for the construction of space X-ray monitors. In this paper, we compare previously reported measurements of prototype lobster eye X-ray optics called P-25 with computer simulations and discuss differences between the theoretical end experimentally obtained results. Usability of this prototype lobster eye and manufacturing technology for the nano-satellite mission is assessed. The specific scientific goals are proposed.
Tests of Lobster Eye Optics for Small Space X-ray Telescope
2011
Abstract The Lobster eye design for a grazing incidence X-ray optics provides wide field of view of the order of many degrees, for this reason it can be a convenient approach for the construction of space all-sky X-ray monitors. We present preliminary results of tests of prototype lobster eye X-ray optics in quasi parallel beam full imaging mode conducted using the 35 m long X-ray beam-line of INAF-OAPA in Palermo (Italy). X-ray images at the focal plane have been taken with a microchannel plate (MCP) detector at several energy values from 0.3 to 8 keV. The gain, the field of view and the angular resolution have been measured and compared with theoretical values.
Simbol-X Mirror Module Thermal Shields: II-Small Angle X-Ray Scattering Measurements
2009
The formation flight configuration of the Simbol-X mission implies that the X-ray mirror module will be open to Space on both ends. In order to reduce the power required to maintain the thermal stability and, therefore, the high angular resolution of the shell optics, a thin foil thermal shield will cover the mirror module. Different options are presently being studied for the foil material of these shields. We report results of an experimental investigation conducted to verify that the scattering of X-rays, by interaction with the thin foil material of the thermal shield, will not significantly affect the performances of the telescope.
Thin plastic shell x-ray optics: an update
2003
We present new results from a program to develop large area X-ray telescopes that are made from thin plastic shells. We use multi-shell cylindrical lenses in a point-to-point configuration to form full aperture images of the small focal spot in a an X-ray tube on a microchannel plate detector. The image data are analyzed to yield radial profiles and encircled energy curves. The derived parameters can be extrapolated to the case of a telescope that is a conical approximation to Wolter 1 optics. The plastic shells can be coated with suitable mono- or multilayers that allow for a wideband coverage of X-ray energies. Our current program is focused on the development of a large area, hard X-ray …