Search results for "detector"
showing 10 items of 3491 documents
The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory
2011
We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than $60^\circ$, detected at the Pierre Auger Observatory. The geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the ~2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution t…
The Large Area Detector of LOFT: the Large Observatory for X-ray Timing
2014
LOFT (Large Observatory for X-ray Timing) is one of the five candidates that were considered by ESA as an M3 mission (with launch in 2022-2024) and has been studied during an extensive assessment phase. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. Its pointed instrument is the Large Area Detector (LAD), a 10 m 2 -class instrument operating in the 2-30keV range, which holds the capability to revolutionise studies of variability from X-ray sources on the millisecond time scales. The LAD instrument has now completed the assessment phase but was not down-selected for launch. However, during the assessment, most o…
Snapshot imaging of postpulse transient molecular alignment revivals
2008
Laser induced field-free alignment of linear molecules is investigated by using a single-shot spatial imaging technique. The measurements are achieved by femtosecond time-resolved optical polarigraphy (FTOP). Individual alignment revivals recorded at high resolution in ${\text{CO}}_{2}$, as well as simultaneous observation of several alignment revivals produced within the rotational period of the ${\text{O}}_{2}$ molecule are reported. The data are analyzed with a theoretical model describing the alignment experienced by each molecule standing within the interaction region observed by the detector. The temporal dynamics, intensity dependence, and degree of alignment are measured and compare…
Si and Si-rich silicon-nitride waveguides for optical transmissions and nonlinear applications around 2 µm
2019
We show that cm-long silicon and silicon-rich silicon nitride waveguides with subwavelength transverse dimensions can efficiently sustain high-speed transmissions at 2 μm. We report the transmission of a 10 Gbit/s signal with negligible power penalty. Parametric conversion in both continuous and pulsed pump regimes is also demonstrated, as well as the spectral broadening of picosecond pulses.
Single photon MIR upconversion detector at room temperature with a PPLN ridge waveguide
2019
International audience; In this paper we describe an upconversion detector in the mid infrared (around 3.5 μm). We take advantage of the PPLN ridge waveguide technology to achieve single photon detection at room temperature on a single spatial mode. With a pump power of 192 mW we obtain a detection efficiency of 0.4% for 22k dark count per second, which corresponds to a noise equivalent power of 3.0 fW · Hz−1/2 and an internal conversion efficiency of 85 %/W of pump.
Upper limit on the diffuse flux of ultrahigh energy tau neutrinos from the Pierre Auger Observatory
2008
The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth’s crust. Tau leptons from ντ charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 are used to place an upper limit on the diffuse flux of ντ at EeV energies. Assuming an E−2ν differential energy spectrum the limit set at 90% C.L. is E2νdNντdEν<1.3×10−7 GeV cm−2 s−1 sr−1 in the energy range 2×1017 eV<E<2×1019 eV.
Zenith distribution and flux of atmospheric muons measured with the 5-line ANTARES detector
2010
The ANTARES high energy neutrino telescope is a three-dimensional array of about 900 photomultipliers distributed over 12 mooring lines installed in the Mediterranean Sea. Between February and November 2007 it acquired data in a 5-line configuration. The zenith angular distribution of the atmospheric muon flux and the associated depth-intensity relation are measured and compared with previous measurements and Monte Carlo expectations. An evaluation of the systematic effects due to uncertainties on environmental and detector parameters is presented.
Large-scale distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory
2012
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 1018 eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 1018 eV from stationary Galactic …
Reactive and organic halogen species in three different European coastal environments
2005
We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was partly re-evaluated. During the recent field campaigns volatile halogenated organic compounds (VHOCs) were determined by a capillary gas chromatograph coupled with an electron capture detector and an inductively coupled plasma mass spectrometer (GC/ECD-ICPMS) in air and wat…
Acoustic properties of plates with unevenly distributed macro perforations backed by woven meshes
2012
A hybrid model describing the acoustic properties of plates with macro-perforations that can be unevenly distributed on the plate surface and backed by woven or precision woven meshes with microscopic perforations is proposed. The plate perforations may be of circular or rectangular shapes. Since the perforated plate may not necessarily be considered as an equivalent fluid, its surface impedance is calculated by the Maa model [Noise Control Eng. J. 29, 77-84 (1987)], whereas the Johnson-Champoux-Allard model [J. Appl. Phys. 70, 1975-1979 (1991)] is used for the mesh. It is observed that the absorption of the carrying plate seems to depend on the hydraulic diameter of the perforations and no…