Study of a high spatial resolution 10B-based thermal neutron detector for application in neutron reflectometry: the Multi-Blade prototype

Although for large area detectors it is crucial to find an alternative to detect thermal neutrons because of the 3He shortage, this is not the case for small area detectors. Neutron scattering science is still growing its instruments' power and the neutron flux a detector must tolerate is increasing. For small area detectors the main effort is to expand the detectors' performances. At Institut Laue-Langevin (ILL) we developed the Multi-Blade detector which wants to increase the spatial resolution of 3He-based detectors for high flux applications. We developed a high spatial resolution prototype suitable for neutron reflectometry instruments. It exploits solid 10B-films employed in a proportional gas chamber. Two prototypes have been constructed at ILL and the results obtained on our monochromatic test beam line are presented here

Phase separation of binary fluids with dynamic temperature

Phase separation of binary fluids quenched by contact with cold external walls is considered. Navier-Stokes, convection-diffusion, and energy equations are solved by lattice Boltzmann method coupled with finite-difference schemes. At high viscosity, different morphologies are observed by varying the thermal diffusivity. In the range of thermal diffusivities with domains growing parallel to the walls, temperature and phase separation fronts propagate towards the inner of the system with power-law behavior. At low viscosity hydrodynamics favors rounded shapes, and complex patterns with different lengthscales appear. Off-symmetrical systems behave similarly but with more ordered configurations.Comment: Accepted for publication in Phys. Rev. E, 11 figures, best quality figures available on reques

Electrical resistivity tomography for studying liquefaction induced by the May 2012 Emilia-Romagna earthquake (Mw = 6.1, northern Italy)

Abstract. This work shows the result of an electrical resistivity tomography (ERT) survey carried out for imaging and characterizing the shallow subsurface affected by the coseismic effects of the Mw = 6.1 Emilia-Romagna (northern Italy) earthquake that occurred on 20 May 2012. The most characteristic coseismic effects were ground failure, lateral spreading and liquefaction that occurred extensively along the paleo-Reno River in the urban areas of San Carlo and Mirabello (southwestern portion of Ferrara Province). In total, six electrical resistivity tomographies were performed and calibrated with surface geological surveys, exploratory boreholes and aerial photo interpretations. This was one of first applications of the electrical resistivity tomography method in investigating coseismic liquefaction

Fluctuation relations in non-equilibrium stationary states of Ising models

Fluctuation relations for the entropy production in non equilibrium stationary states of Ising models are investigated by Monte Carlo simulations. Systems in contact with heat baths at two different temperatures or subject to external driving will be studied. In the first case, by considering different kinetic rules and couplings with the baths, the behavior of the probability distributions of the heat exchanged in a time $\tau$ with the thermostats, both in the disordered and in the low temperature phase, are discussed. The fluctuation relation is always verified in the large $\tau$ limit and deviations from linear response theory are observed. Finite-$\tau$ corrections are shown to obey a scaling behavior. In the other case the system is in contact with a single heat bath but work is done by shearing it. Also for this system the statistics collected for the mechanical work shows the validity of the fluctuation relation and preasymptotic corrections behave analogously to the case with two baths.Comment: 9 figure

Some Restrictions Abroad Affecting Corporations

A neutron detector concept based on solid layers of boron carbide enriched in 1 B has been in development for the last few years as an alternative for He-3 by collaboration between the ILL, ESS and Linkoping University. This Multi-Grid detector uses layers of aluminum substrates coated with (B4C)-B-10 on both sides that are traversed by the incoming neutrons. Detection is achieved using a gas counter readout principle. By segmenting the substrate and using multiple anode wires, the detector is made inherently position sensitive. This development is aimed primarily at neutron scattering instruments with large detector areas, such as time-of-flight chopper spectrometers. The most recent prototype has been built to be interchangeable with the He-3 detectors of IN6 at ILL. The 1 B detector has an active area of 32 x 48 cm(2). It was installed at the IN6 instrument and operated for several weeks, collecting data in parallel with the regularly scheduled experiments, thus providing the first side-by-side comparison with the conventional He-3 detectors. Results include an efficiency comparison, assessment of the in-detector scattering contribution, sensitivity to gamma-rays and the signal-to-noise ratio in time-of-flight spectra. The good expected performance has been confirmed with the exception of an unexpected background count rate. This has been identified as natural alpha activity in aluminum. New convertor substrates are under study to eliminate this source of background

Addition of the apical oblique projection increases the detection of acute traumatic shoulder abnormalities in adults

Purpose Plain radiographic evaluation of acute shoulder trauma in adults requires a minimum of two projections, commonly the anteroposterior (AP) and lateral scapular projections, with additional projections taken for diagnosis. The aim of this retrospective study was to determine whether the addition of the apical oblique (AO) projection to the AP and lateral scapular projections increases the number and/or alters the types of abnormalities detected in the examination of acute shoulder trauma. Methods Examinations of 56 adults who had undergone three-projection (AP, lateral scapular, AO) radiographic shoulder examination for acute trauma were allocated into two-projection (AP, lateral scapular) and three-projection cases and assessed by a radiologist. The differences in number and types of abnormalities between the two-projection and three-projection cases were quantified using the one-tailed t test and chi-square goodness-of-fit test, respectively. Results Test-retest reliability was moderate (intra-class correlation coefficient [95%CI], 0.56 [0.15 to 0.80]) for number, and almost perfect (kappa [95%CI], 0.94 [0.85 to 1.00]) for types, of abnormalities detected. There was a significant increase in the number of abnormalities detected across all three-projection versus two-projection cases (difference in means [95%CI], 0.20 [0.01 to 0.39]) and for fractures (difference in means [95%CI], 0.30 [0.11 to 0.49]), but no difference in the types of abnormalities detected (χ 2 = 4.7, p = 0.19). Conclusion This study suggests that adding the AO projection to two-projection examination of acute shoulder trauma increases the number of abnormalities detected; this has potential implications for patient management. Further research investigating differences in types of abnormalities detected between two-projection and three-projection cases is warranted

Bio-herbicidal potential of the essential oils from different Rosmarinus Officinalis L. chemotypes in laboratory assays

The current study aimed to assess the allelopathic effect of Rosmarinus officinalis L. essential oils (EOs) to define the potent effect against weed species, by exploring distinct chemotypes and their main compounds. The EOs from eight accessions were characterized. Their components were identified by gas chromatography, and four chemotypes were defined; C1 (α-pinene), C2 (camphor), C3 (α-pinene/1,8-cineole), and C4 (α-pinene/1,8-cineole/camphor). Four concentrations of the EOs (400, 800, 1200, and 2400 μL/L) and the main compounds of each chemotype were tested in a laboratory assay against Amaranthus retroflexus L. and Lolium perenne L. in pre-and post-germination. The results showed that the EOs significantly affected all the tested parameters (germination, early growth, and physiological and histological parameters of the weeds under study) in a dose, chemotype, and species dependent manner. A. retroflexus was more sensitive than L. perenne at germination level being significantly inhibited at the lowest dose of all the chemotypes. The latter all exhibited significant effects but with a higher potency of C2 (camphor chemotype) and C3 (α-pinene/1,8-cineole chemotype), as well qualitative differences in the induced damage. Our results thus increase knowledge about the role of the monoterpene composition in bioherbicidal effect, which can help in the development of EO based bio-herbicides

Time dynamics of background noise in geoelectrical and geochemical signals: an application in a seismic area of Southern Italy

We analyse geoelectrical and geochemical time series jointly measured by means of a multiparametric automatic station close to an anomalous fluid emission in Val d’Agri (Basilicata, Italy). The investigated area is located on Southern Apennine chain that in past and recent years was interested by destructive earthquakes. After a complete pre-processing of time series, we analyse the fluctuations triggered by the seasonal cycles and focus our attention on the possible link between geoelectrical and geochemical signals. In order to extract quantitative dynamical information from experimental time series, we detect scaling laws in power spectra that are typical fingerprints of fractional Brownian processes. After this analysis, the problem of the identification of extreme events in the time series has been approached. We consider significant anomalous patterns only when more consecutive values are above/below a fixed threshold in almost two of the time series jointly measured. We give the first preliminary results about the comparison between anomalous patterns detected in geoelectrical and geochemical parameters and the local seismic activity and, finally, analyse the implications with the earthquake prediction problem