Background simulations for the Large Area Detector onboard LOFT     

Riccardo Campana  Marco Feroci  Ettore Del Monte  Teresa Mineo  Niels Lund  George W. Fraser 《Experimental Astronomy》2013,36(3):451-477

The Large Observatory For X-ray Timing (LOFT), currently in an assessment phase in the framework the ESA M3 Cosmic Vision programme, is an innovative medium-class mission specifically designed to answer fundamental questions about the behaviour of matter, in the very strong gravitational and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of ～10 m² at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2?30 keV, achieving about 5 mCrab in the most important 2–10 keV energy band. Moreover, simulations show an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than the requirement of 1 %, and actually meeting the 0.25 % science goal.  相似文献   

The Water and Energy Connection: A Recent Dialogue     

byMichael E. Campana 《Ground water》2009,47(6):763-765

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Geomaterials related to photovoltaics: a nanostructured Fe-bearing kuramite,Cu<Subscript>3</Subscript>SnS<Subscript>4</Subscript>     

Francesco Di Benedetto  Ilaria Bencistà  Francesco D’Acapito  Silvia Frizzera  Andrea Caneschi  Massimo Innocenti  Alessandro Lavacchi  Giordano Montegrossi  Werner Oberhauser  Maurizio Romanelli  Herbert Dittrich  Luca A. Pardi  Gerold Tippelt  Georg Amthauer 《Physics and Chemistry of Minerals》2016,43(8):535-544

The successful synthesis of nanoparticles of Fe-bearing kuramite, (Cu,Fe)₃SnS₄, is reported in this study. Nanocrystalline powders were obtained through a mild, environmentally friendly and scalable solvothermal approach, in a single run. The sample was the object of a multidisciplinary investigation, including X-ray diffraction and absorption, scanning electron microscopy and microanalysis, electron paramagnetic resonance, diffuse reflectance and Mössbauer spectroscopy as well as SQUID magnetometry. The nanoparticles consist of pure Fe-bearing kuramite, exhibiting tetragonal structure. The valence state of the metal cations was assessed to be Cu⁺, Sn⁴⁺ and Fe³⁺. The material presents a band gap value of 1.6 eV, which is fully compatible with solar cell applications. The uptake of Fe by nanokuramite opens a compositional field where the physical properties can be tuned. We thus foster the application of Fe-bearing nanokuramite for photovoltaics and energy storage purposes.  相似文献   

Application of the MST clustering to the high energy γ-ray sky. IV—Blazar candidates found as possible counterparts of photon clusters     

R. Campana  E. Massaro  E. Bernieri 《Astrophysics and Space Science》2016,361(11):367

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Multiproxy record for the last 4500 years from Lake Shkodra (Albania/Montenegro)     

Giovanni Zanchetta  Aurelien Van Welden  Ilaria Baneschi  Russell Drysdale  Laura Sadori  Neil Roberts  Marco Giardini  Christian Beck  Vincenzo Pascucci  Roberto Sulpizio 《第四纪科学杂志》2012,27(8):780-789

A multi‐proxy record is presented for approximately the last 4500 cal a BP from Lake Shkodra, Albania/Montenegro. Lithological analyses, C/N ratio and δ¹³C of the organic and inorganic carbon component suggest that organic matter and bulk carbonate are predominantly authigenic. The δ¹⁸O record of bulk carbonate indicates the presence of two prominent wet periods: one at ca. 4300 cal a BP and one at ca. 2500–2000 cal a BP. The latter phase is also found in southern Spain and Central Italy, and represents a prominent event in the western and central Mediterranean. In the last 2000 years, four relatively wet intervals occurred between ca. 1800 and 1500 cal a BP (150–450 AD), 1350–1250 (600–700 AD), 1100–800 (850–1150 AD), and at ca. 90 cal a BP (1860 AD). Between ca. 4100 and 2500 cal a BP δ¹⁸O values are relatively high, with three prominent peaks indicating drier conditions at ca. 4100–4000 cal a BP, ca. 3500 and at ca. 3300 cal a BP. Four additional drier events are identified at 1850 (ca. 100 AD), 1400 (ca. 550 AD), 1150 (800 AD) and ca.750 cal a BP (1200 AD). The pollen record does not show changes in accordance with these episodes owing to the poor sensitivity of vegetation in this area, which is dominated by an orographic rainfall effect and where changes in altitudinal vegetation belts do not affect the pollen rain in the lake catchment. However, since ca. 900 cal a BP a significant decrease in the percentage arboreal pollen and in pollen concentrations suggest major deforestation produced by human activities. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Ordovician system     

Maxwell R. Banks  A. H. Blissett  K. L. Burns  B. Campana  R. G. Elms  I. B. Jennings 《Australian Journal of Earth Sciences》2013,60(2):147-176

Rocks in the Brungle‐Darbalara area of the Tumut Trough form two distinct domains: basement (mainly Bullawyarra Schist), of Cambrian‐Ordovician age, and an Ordovician ‐ Early Silurian sedimentary and volcanic cover sequence. These two domains are separated by a sharp discontinuity that marks an abrupt change in rock type, structure, metamorphic grade and deformation style. Cover sequences have undergone only one major penetrative deformation during the Late Silurian, involving sub‐greenschist facies metamorphism and upright folding. In contrast, the basement also underwent at least two older deformations at greenschist facies and contains distinct high‐strain zones subconcordant with the basement‐cover contact. The high‐strain zones, characterized by a ubiquitous south‐southeast trending mineral lineation, record a discontinuous history of ductile followed by brittle behaviour, consistent with an extensional origin.

The structural and metamorphic discontinuity separating basement from Silurian cover is characterized by widespread cataclasis and alteration and is interpreted as a major detachment fault associated with lithospheric extension and the development of the Tumut Trough in the Early Silurian. During the main period of movement on the detachment, which took place prior to intrusion of the Blacks Flat Diorite into the Bullawyarra Schist, mafic and serpentinized ultramafic rocks either were tectonically emplaced or intruded into the high strain zones. This preceded and accompanied extensional faulting of the cover and deposition of Silurian trough sediments and volcanics which unconformably overlie and onlap older units.

The development of the Tumut Trough, in the Brungle‐Darbalara area, bears many similarities with that of Cordilleran metamorphic core complexes. Such a model is consistent with environments suggested for the trough by previous workers. The south‐southeast extension direction parallels the trough‐bounding faults and implies an overall strike‐slip tectonic setting.  相似文献   

The first outburst of the new magnetar candidate SGR 0501+4516     

N. Rea  G. L. Israel  R. Turolla  P. Esposito  S. Mereghetti  D. Götz  S. Zane  A. Tiengo  K. Hurley  M. Feroci  M. Still  V. Yershov  C. Winkler  R. Perna  F. Bernardini  P. Ubertini  L. Stella  S. Campana  M. van der Klis  P. Woods 《Monthly notices of the Royal Astronomical Society》2009,396(4):2419-2432

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A geostatistical approach for mapping and uncertainty assessment of geogenic radon gas in soil in an area of southern Italy   总被引：2，自引：2，他引：0  

Gabriele Buttafuoco  Adalisa Tallarico  Giovanni Falcone  Ilaria Guagliardi 《Environmental Earth Sciences》2010,61(3):491-505

Spatial distribution of concentrations of radon gas in the soil is important for defining high risk areas because geogenic radon is the major potential source of indoor radon concentrations regardless of the construction features of buildings. An area of southern Italy (Catanzaro-Lamezia plain) was surveyed to study the relationship between radon gas concentrations in the soil, geology and structural patterns. Moreover, the uncertainty associated with the mapping of geogenic radon in soil gas was assessed. Multi-Gaussian kriging was used to map the geogenic soil gas radon concentration, while conditional sequential Gaussian simulation was used to yield a series of stochastic images representing equally probable spatial distributions of soil radon across the study area. The stochastic images generated by the sequential Gaussian simulation were used to assess the uncertainty associated with the mapping of geogenic radon in the soil and they were combined to calculate the probability of exceeding a specified critical threshold that might cause concern for human health. The study showed that emanation of radon gas radon was also dependent on geological structure and lithology. The results have provided insight into the influence of basement geochemistry on the spatial distribution of radon levels at the soil/atmosphere interface and suggested that knowledge of the geology of the area may be helpful in understanding the distribution pattern of radon near the earth’s surface.  相似文献   

Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample     

D. Rizzuto  C. Guidorzi  P. Romano  S. Covino  S. Campana  M. Capalbi  G. Chincarini  G. Cusumano  D. Fugazza  V. Mangano  A. Moretti  M. Perri  G. Tagliaferri 《Monthly notices of the Royal Astronomical Society》2007,379(2):619-628

We test the gamma-ray burst (GRB) correlation between temporal variability and peak luminosity of the γ-ray profile on a homogeneous sample of 36 Swift /Burst Alert Telescope (BAT) GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the six GRBs with low luminosity (  <5 × 10⁵⁰   erg s⁻¹  in the rest-frame 100–1000 keV energy band) are ignored. We confirm that the considerable scatter of the correlation already known is not due to the combination of data from different instruments with different energy bands, but it is intrinsic to the correlation itself. Thanks to the unprecedented sensitivity of Swift /BAT, the variability/peak luminosity correlation is tested on low-luminosity GRBs. Our results show that these GRBs are definite outliers.  相似文献   

Esterase activities in the bivalve mollusc Adamussium colbecki as a biomarker for pollution monitoring in the Antarctic marine environment     

Bonacci S  Browne MA  Dissanayake A  Hagger JA  Corsi I  Focardi S  Galloway TS 《Marine pollution bulletin》2004,49(5-6):445-455

Marine environments are continuously being threatened by a large number of xenobiotics from anthropogenic sources. Even in sparsely populated and relatively pristine areas, such as Antarctica, hazardous chemicals can pose a serious environmental problem. The main aims of the present study were to (1) validate and optimize an analytical technique utilizing a microtitre-plate photometer to ascertain background levels of esterase activities in the Antarctic bivalve Adamussium colbecki, (2) carry out in situ monitoring of esterase activities to assess any potential environmental impacts of the Italian Scientific Antarctic Base "Terra Nova Bay" on the surrounding marine area. Results showed the presence of organophosphorous-sensitive cholinesterase (ChE) and carboxylesterase (CbE) activities in the gills of A. colbecki and optimal assay conditions were comparable with those found for bivalve species from temperate areas. A higher sensitivity of ChE versus acetylthiocholine activity in A. colbecki to chlorpyrifos compared to species from temperate areas may also be inferred. The in situ study indicated no differences in the environmental quality of the three study sites located around the Italian Base.  相似文献