Search results for "Detector"
showing 10 items of 3491 documents
Comparative assessment of solid-phase extraction clean-up procedures, GC columns and perfluoroacylation reagents for determination of type B trichoth…
2005
Abstract Various solid-phase extraction (SPE) procedures for clean-up, two perfluoroacylation reagents (pentafluoropropionic anhydride (PFPA) and heptafluorobutyric anhydride (HFBA)) and two chromatographic columns (HP-1701 and HP-5) have been assessed comparatively to achieve the determination of type B trichothecenes (deoxynivalenol (DON), nivalenol (NIV), 3- and 15-acetyldeoxynivalenol (3- and 15-ADON)) in wheat grain by gas chromatography (GC)–electron-capture detection (ECD). Spiked wheat samples were extracted with acetonitrile–water (84:16, v/v). Tested SPE procedures were MycoSep 225 column, Florisil and different cartridges prepared in the laboratory with mixtures of various sorben…
Biogenic volatile organoiodine and organobromine hydrocarbons in the Atlantic Ocean from 42°N to 72°S
1997
During the cruise ANT X/1 and 2 of the research vessel Polarstern from November 1991 to March 1992, 39 surface water samples of the Atlantic Ocean from 42°N to 72.5°S were collected and analysed for their concentration of volatile iodinated and brominated hydrocarbons. The concentration of chlorophyll-a was used as an indicator for phytoplankton, which is one of the main producers of iodinated and brominated compounds in the ocean. For determination of chlorophyll-a, fluorescence spectroscopy was applied, whereas the measurement of halogenated volatile hydrocarbons was carried out by a purge and trap system with subsequent gas chromatographic separation and detection by an electron capture …
Risk assessment of beauvericin, enniatins and fusaproliferin present in follow-up infant formula by in vitro evaluation of the duodenal and colonic b…
2014
Abstract In this study, 72 samples of follow-up infant formula of Spanish origin were analyzed for the presence of the mycotoxins beauvericin (BEA), enniatins (ENs) (A, A1, B, B1), and fusaproliferin (FUS). The samples analyzed were extracted three times with ethyl acetate and then the mycotoxins were identified and quantified using a liquid chromatography (LC) coupled to a diode array detector (DAD). The positive samples analyzed in this study were digested through a simulated gastrointestinal digestion model, which permit to simulate the physiological condition of the human gastrointestinal tract (duodenal and colonic compartments) in order to assess the bioaccessibility of the bioactive …
The detection efficiency of the clover Ge-detectors array at the RITU-GREAT facility
2015
Absolute detection efficiency depending upon its position along the beam line is determined for three germanium detectors, that are part of the GREAT spectrometer at the RITU separator focal plane. The efficiency is determined for an energy range from 80 keV to 1400 keV for all three detectors as an array and also individually using digital electronics. The optimal position for the detector array has been defined for two configurations of the GREAT spectrometer: with planar detector and without it. The obtained results have been compared with three references: a simulation prepared especially for this setup by another student, a previous study that was carried out by applying analogue elect…
Upper limits on the isotropic gravitational-wave background from Advanced LIGO and Advanced Virgo's third observing run
2021
We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO's and Advanced Virgo's third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density $\Omega_{\rm GW}\leq 5.8\times 10^{-9}$ at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform in the log of the strength of the GWB, with 99% of the sensitivity comi…
Solid-state-biased coherent detection of ultra-broadband terahertz pulses
2017
Significant progress in nonlinear and ultrafast optics has recently opened new and exciting opportunities for terahertz (THz) science and technology, which require the development of reliable THz sources, detectors, and supporting devices. In this work, we demonstrate the first solid-state technique for the coherent detection of ultra-broadband THz pulses (0.1-10 THz), relying on the electric-field-induced second-harmonic generation in a thin layer of ultraviolet fused silica. The proposed CMOS-compatible devices, which can be realized with standard microfabrication techniques, allow us to perform ultra-broadband detection with a high dynamic range by employing probe laser powers and bias v…
Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications
2009
Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector…
Thermoelectric Radiation Detector Based on Superconductor-Ferromagnet Systems
2017
We suggest an ultrasensitive detector of electromagnetic fields exploiting the giant thermoelectric effect recently found in superconductor-ferromagnet hybrid structures. Compared with other types of superconducting detectors where the detected signal is based on variations of the detector impedance, the thermoelectric detector has the advantage of requiring no external driving fields. This is especially relevant in multipixel detectors, where the number of bias lines and the heating induced by them are an issue. We propose different material combinations to implement the detector and provide a detailed analysis of its sensitivity and speed. In particular, we perform a proper noise analysis…
Search for Cosmic Neutrino Point Sources with Four Year Data of the ANTARES Telescope
2012
In this paper, a time-integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E ¿2 n; spectrum, these flux limits are at 1-10 ¿10¿8 GeV cm¿2 s¿1 for declinations ranging from ¿90° to 40°. Limits for specific models of RX J1713.7¿3946 and Vela X, which include information on the source morphology and spectrum, are also given.
Measurement of the cosmic-ray energy spectrum above 2.5×1018 eV using the Pierre Auger Observatory
2020
We report a measurement of the energy spectrum of cosmic rays for energies above 2.5×10^18 eV based on 215,030 events recorded with zenith angles below 60°. A key feature of the work is that the estimates of the energies are independent of assumptions about the unknown hadronic physics or of the primary mass composition. The measurement is the most precise made hitherto with the accumulated exposure being so large that the measurements of the flux are dominated by systematic uncertainties except at energies above 5×10^19 eV. The principal conclusions are(1) The flattening of the spectrum near 5×10^18 eV, the so-called "ankle,"is confirmed.(2) The steepening of the spectrum at around 5×10^19…