66 research outputs found
The 1999-2000 seismic experiment of Macas swarm (Ecuador) in relation with rift inversion in Subandean foothills
International audienceWe propose to explain the origin of the double trend in seismicity of the Macas swarm in the Subandean Cordillera of CutucĂș (Ecuador) and characterize the corresponding active deformation of that region. For that purpose, seismological and geological data have been used, with the deployment of a temporary seismological array, with geological field observations and image processing. We found that some earthquakes are aligned on a well known NNE SSW trend corresponding to the orientation of the nodal planes of the reverse focal mechanism of the Mw=7.0 1995 Macas earthquake as for its aftershocks. Nevertheless, many smaller events are aligned on an unexpected NNW SSE trend inside the CutucĂș Cordillera. We interpret these two orientations of the Macas swarm as linked to Subandean basement thrusts inherited from the inversion tectonics of a NNE SSW trending Triassic Jurassic rift, which has been uplifted and partly extruded in the CutucĂș Cordillera. The present partitioning of this part of the Subandean deformation is controlled by pre-existing NNE SSW to NNW SSE Triassic Jurassic normal faults that have been subsequently compressed transpressed and reactivated into reverse faults. Major boundary faults of the rift were NNE SSW oriented and correspond now to some main Subandean thrusts as confirms the focal mechanism of the 1995 main shock located on the eastern border (Morona frontal thrust) and the orientation of its aftershocks. In the CutucĂș Cordillera, the double orientation of present swarm can be interpreted as the result of accommodation of deformation along NNW SSE pre-existing faults inside the inverted rift system, linked to the motion of the Morona frontal NNE SSW thrust
Experimental study of a liquid Xenon PET prototype module
A detector using liquid Xenon in the scintillation mode is studied for
Positron Emission Tomography (PET). The specific design aims at taking full
advantage of the liquid Xenon properties. It does feature a promising
insensitive to any parallax effect. This work reports on the performances of
the first LXe prototype module, equipped with a position sensitive PMT
operating in the VUV range (178 nm).Comment: Proc. of the 7th International Workshops on Radiation Imaging
Detectors (IWORID-7), Grenoble, France 4-7 July 200
Theoretical study and experimental result of the RF coupler prototypes of Spiral2
JACoW web site THPCH160International audienceSpiral2 is a 40 MeV-5mA deuterons and a 14.5 MeV/u-1mA heavy ions superconducting linac under construction at GANIL. The RF couplers have to provide 12 kW CW power to the cavities at 88 MHz for an accelerating field of 6.5 MV/m. Two solutions corresponding to two different technologies have been designed and two prototypes have been built. We present the technical proposals ans issues as well as the results (manufacturing, test at low and high power, multipacting...) leading to the final choice
Design and construction of a Cherenkov imager for charge measurement of nuclear cosmic rays
A proximity focusing Cherenkov imager called CHERCAM, has been built for the
charge measurement of nuclear cosmic rays with the CREAM instrument. It
consists of a silica aerogel radiator plane across from a detector plane
equipped with 1,600 1" diameter photomultipliers. The two planes are separated
by a ring expansion gap. The Cherenkov light yield is proportional to the
charge squared of the incident particle. The expected relative light collection
accuracy is in the few percents range. It leads to an expected single element
separation over the range of nuclear charge Z of main interest 1 < Z < 26.
CHERCAM is designed to fly with the CREAM balloon experiment. The design of the
instrument and the implemented technical solutions allowing its safe operation
in high altitude conditions (radiations, low pressure, cold) are presented.Comment: 24 pages, 19 figure
The secondary eclipses of WASP-19b as seen by the ASTEP 400 telescope from Antarctica
The ASTEP (Antarctica Search for Transiting ExoPlanets) program was
originally aimed at probing the quality of the Dome C, Antarctica for the
discovery and characterization of exoplanets by photometry. In the first year
of operation of the 40 cm ASTEP 400 telescope (austral winter 2010), we
targeted the known transiting planet WASP-19b in order to try to detect its
secondary transits in the visible. This is made possible by the excellent
sub-millimagnitude precision of the binned data. The WASP-19 system was
observed during 24 nights in May 2010. The photometric variability level due to
starspots is about 1.8% (peak-to-peak), in line with the SuperWASP data from
2007 (1.4%) and larger than in 2008 (0.07%). We find a rotation period of
WASP-19 of 10.7 +/- 0.5 days, in agreement with the SuperWASP determination of
10.5 +/- 0.2 days. Theoretical models show that this can only be explained if
tidal dissipation in the star is weak, i.e. the tidal dissipation factor Q'star
> 3.10^7. Separately, we find evidence for a secondary eclipse of depth 390 +/-
190 ppm with a 2.0 sigma significance, a phase consistent with a circular orbit
and a 3% false positive probability. Given the wavelength range of the
observations (420 to 950 nm), the secondary transit depth translates into a day
side brightness temperature of 2690(-220/+150) K, in line with measurements in
the z' and K bands. The day side emission observed in the visible could be due
either to thermal emission of an extremely hot day side with very little
redistribution of heat to the night side, or to direct reflection of stellar
light with a maximum geometrical albedo Ag=0.27 +/- 0.13. We also report a
low-frequency oscillation well in phase at the planet orbital period, but with
a lower-limit amplitude that could not be attributed to the planet phase alone,
and possibly contaminated with residual lightcurve trends.Comment: Accepted for publication in Astronomy and Astrophysics, 13 pages, 13
figure
ASTEP South: An Antarctic Search for Transiting ExoPlanets around the celestial South pole
ASTEP South is the first phase of the ASTEP project (Antarctic Search for
Transiting ExoPlanets). The instrument is a fixed 10 cm refractor with a 4kx4k
CCD camera in a thermalized box, pointing continuously a 3.88 degree x 3.88
degree field of view centered on the celestial South pole. ASTEP South became
fully functional in June 2008 and obtained 1592 hours of data during the 2008
Antarctic winter. The data are of good quality but the analysis has to account
for changes in the point spread function due to rapid ground seeing variations
and instrumental effects. The pointing direction is stable within 10 arcseconds
on a daily timescale and drifts by only 34 arcseconds in 50 days. A truly
continuous photometry of bright stars is possible in June (the noon sky
background peaks at a magnitude R=15 arcsec-2 on June 22), but becomes
challenging in July (the noon sky background magnitude is R=12.5 arcsec?2 on
July 20). The weather conditions are estimated from the number of stars
detected in the field. For the 2008 winter, the statistics are between 56.3 %
and 68.4 % of excellent weather, 17.9 % to 30 % of veiled weather and 13.7 % of
bad weather. Using these results in a probabilistic analysis of transit
detection, we show that the detection efficiency of transiting exoplanets in
one given field is improved at Dome C compared to a temperate site such as La
Silla. For example we estimate that a year-long campaign of 10 cm refractor
could reach an efficiency of 69 % at Dome C versus 45 % at La Silla for
detecting 2-day period giant planets around target stars from magnitude 10 to
15. This shows the high potential of Dome C for photometry and future planet
discoveries. [Short abstract
Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data
The Mw 7.7 2007 November 14 earthquake had an epicentre located close to the city of Tocopilla, at the southern end of a known seismic gap in North Chile. Through modelling of Global Positioning System (GPS) and radar interferometry (InSAR) data, we show that this event ruptured the deeper part of the seismogenic interface (30â50 km) and did not reach the surface. The earthquake initiated at the hypocentre and was arrested ~150 km south, beneath the Mejillones Peninsula, an area already identified as an important structural barrier between two segments of the PeruâChile subduction zone. Our preferred models for the Tocopilla main shock show slip concentrated in two main asperities, consistent with previous inversions of seismological data. Slip appears to have propagated towards relatively shallow depths at its southern extremity, under the Mejillones Peninsula. Our analysis of post-seismic deformation suggests that small but still significant post-seismic slip occurred within the first 10 d after the main shock, and that it was mostly concentrated at the southern end of the rupture. The post-seismic deformation occurring in this period represents ~12â19 per cent of the coseismic deformation, of which ~30â55 per cent has been released aseismically. Post-seismic slip appears to concentrate within regions that exhibit low coseismic slip, suggesting that the afterslip distribution during the first month of the post-seismic interval complements the coseismic slip. The 2007 Tocopilla earthquake released only ~2.5 per cent of the moment deficit accumulated on the interface during the past 130 yr and may be regarded as a possible precursor of a larger subduction earthquake rupturing partially or completely the 500-km-long North Chile seismic gap
Predictive Modelling Of Temperature And Water Activity (Solutes) On The In Vitro Radial Growth Of Botrytis Cinerea Pers
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