Spatial pattern of denudation in a lithologically controlled sub-tropical flat landscape: Insights from the Kimberley region, NW Australia

The Kimberley region, northwest Australia, is well known for its expansive and diverse collection of prehistorical aboriginal rock art that potentially dates back to 40,000 years ago. The region is characterized by a tropical, semiarid climate with a monsoonal rainfall distribution and a flat landscape interrupted by massive sandstone mesas and deeply incised bedrock river gorges. In order to constrain the chronology of the rock art it is necessary to quantify the spatial and temporal dimensions of landscape evolution. We report cosmogenic 10Be and 26Al concentrations in modern fluvial sediment collected from 27 catchments with areas spanning several orders of magnitude (13.6 – 13,900 km2 ). All catchments are characterized by a very low topographic gradient (average basin slopes < 3◦ ) and subdued local relief of at most 200m. Assuming negligible sediment storage times and rapid sediment transport driven by the annual monsoonal washout, we calculate 10Be based catchment-wide denudation rates ranging between 1.87 ± 0.23 and 9.48 ± 1.05 m.Myr−1 . These low rates are among the slowest recorded in the world, despite the strong climatic seasonality of the region. Our measured denudation rates exhibit a strong correlation with topographic gradient, which in the overall flat landscapes of the Kimberley, is controlled by the prevailing sandstone bedrock lithology and the presence of numerous escarpments adjacent to the river channels. We present a modelling approach that makes use of the 26Al/10Be ratio in the fluvial sediments as a source tracer (ie escarpment cliffs, river channels, plateau bedrocks), and use this to explore the control and retreat rate of the eroding escarpment cliffs in order to provide information on the spatial distribution of denudation in the landscape. © Author(s) 2016. CC Attribution 3.0 License

Electromagnetic characterization of the 990 ton gapless magnets for the OPERA experiment

The instrumented targets of the OPERA neutrino experiment are complemented by two massive spectrometers based on gapless iron magnets. In 2006, a systematic assessment of their electromagnetic properties have been carried out. In this document, we report the results of such characterization and demonstrate that the achieved performance fulfill the physics requirements for the study of νμ→ντ oscillations

Alternative Fourier Expansions for Inverse Square Law Forces

Few-body problems involving Coulomb or gravitational interactions between pairs of particles, whether in classical or quantum physics, are generally handled through a standard multipole expansion of the two-body potentials. We discuss an alternative based on a compact, cylindrical Green's function expansion that should have wide applicability throughout physics. Two-electron "direct" and "exchange" integrals in many-electron quantum systems are evaluated to illustrate the procedure which is more compact than the standard one using Wigner coefficients and Slater integrals.Comment: 10 pages, latex/Revtex4, 1 figure

Aged Drilled Cuttings Offshore Gabon: New Methodology for Assessing Their Impact

During E&amp;P offshore activities, and in particular during drilling operations, the living conditions of the flora and fauna on the seabed may be disturbed.The paper describes the study made for assessing the actual impact of the discharged cuttings, the regenerating capacity of the ecosystem and the medium and long-term recolonization processes, based on in situ measurements. A previous study undertaken on cuttings recently discharged offshore Congo measured kinetics of space and time restoration of the drilling site. To validate the results we carried out a similar study dedicated on aged cuttings offshore Gabon. Usual process for monitoring biological effects of cuttings includes several approaches such as benthic macrofauna (&gt; 1mm size) studies, physicochemical analysis of sediment and ecotoxicological tests. One of the key features of our study was to add, to this process, a study of the benthic meiofauna (0.1 to 1mm size). Experiments conducted demonstrated: -very low concentrations of hydrocarbons stemming out from the cuttings, -a very low toxicity of sediment, -no benthic macrofauna community alteration, -no change in the communities of actual and fossil foraminifera (meiofauna) and, -last but not least, that the study of the benthic meiofauna improves the quality of the assessment made

Axion searches with the EDELWEISS-II experiment

We present new constraints on the couplings of axions and more generic axion-like particles using data from the EDELWEISS-II experiment. The EDELWEISS experiment, located at the Underground Laboratory of Modane, primarily aims at the direct detection of WIMPs using germanium bolometers. It is also sensitive to the low-energy electron recoils that would be induced by solar or dark matter axions. Using a total exposure of up to 448 kg.d, we searched for axion-induced electron recoils down to 2.5 keV within four scenarios involving different hypotheses on the origin and couplings of axions. We set a 95% CL limit on the coupling to photons $g_{A\gamma}<2.13\times 10^{-9}$ GeV$^{-1}$ in a mass range not fully covered by axion helioscopes. We also constrain the coupling to electrons, $g_{Ae} < 2.56\times 10^{-11}$, similar to the more indirect solar neutrino bound. Finally we place a limit on $g_{Ae}\times g_{AN}^{\rm eff}<4.70 \times 10^{-17}$, where $g_{AN}^{\rm eff}$ is the effective axion-nucleon coupling for $^{57}$Fe. Combining these results we fully exclude the mass range $0.91\,{\rm eV}<m_A<80$ keV for DFSZ axions and $5.73\,{\rm eV}<m_A<40$ keV for KSVZ axions

The instrumented magnets for the OPERA experiment: construction and commissioning

The design and construction of the 990-ton gapless iron magnets for the OPERA experiment represent a major challenge from the point of view of mechanics, electric and heat engineering. Two of such magnets have been built in a deep underground hall of the Gran Sasso laboratories between 2003 and 2006 and they have been switched on for the first time in March 2006. In this paper we discuss the construction and characterization of these devices. First experience with the CNGS beam are also reported. © 2007 Elsevier B.V. All rights reserved

Measurement of Deeply Virtual Compton Scattering with a Polarized Proton Target

The longitudinal target-spin asymmetry A_UL for the exclusive electroproduction of high energy photons was measured for the first time in p(e,e'p\gamma). The data have been accumulated at Jefferson Lab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH_3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the Deeply Virtual Compton Scattering and Bethe-Heitler processes. The amplitude of the sin(phi) moment is 0.252 +/- 0.042(stat) +/- 0.020(sys). Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H-tilde.Comment: Modified text slightly, added reference

Electroproduction of ϕ(1020)\phi(1020) mesons at 1.4≤Q2≤1.4\leq Q^2\leq GeV2^2 measured with the CLAS spectrometer

Electroproduction of exclusive $\phi$ vector mesons has been studied with the CLAS detector in the kinematical range $1.4\leq Q^2\leq 3.8$ GeV$^{2}$, $0.0\leq t^{\prime}\leq 3.6$ GeV$^{2}$, and $2.0\leq W\leq 3.0$ GeV. The scaling exponent for the total cross section as $1/(Q^2+M_{\phi}^2)^n$ was determined to be $n=2.49\pm 0.33$. The slope of the four-momentum transfer $t'$ distribution is $b_{\phi}=0.98 \pm 0.17$ GeV$^{-2}$. Under the assumption of s-channel helicity conservation (SCHC), we determine the ratio of longitudinal to transverse cross sections to be $R=0.86 \pm 0.24$. A 2-gluon exchange model is able to reproduce the main features of the data.Comment: Phys Rev C, 15 pages, 18 figure