An active dipole for cosmic ray radiodetection with CODALEMA

A paraître dans NIM AInternational audienceThe CODALEMA experiment detects the electromagnetic pulses radiated during the development of Extensive Air Showers (EAS). Since 2005, in addition to spiral log-periodic antennas, ultra broad bandwidth active dipoles have been designed to detect the full electric pulse shape of these signals. A few performances of these new detectors are presented

Predictors of inappropriate hospital days in a department of internal medicine

Background This study aimed to identify predictors of inappropriate hospital days in a deparUnent of internal medicine, as a basis for quality improvement interventions. Methods The appropriateness of 5665 hospital days contributed by 500 patients admitted to the Department of Internal Medicine, Geneva University Hospitals, Switzerland, was assessed by means of the Appropriateness Evaluation Protocol. Predictor variables included patient's age and sex, manner of admission and discharge, and characteristics of hospital days (weekend, holiday, sequence). Results Overall, 15% of hospital admissions and 28% of hospital days were rated as inappropriate. In multivariate models, inappropriate hospital days were more frequent among patients whose admission was inappropriate (odds ratio [OR] = 5.3, 95% CI: 3.1-8.4) and among older patients (80-95 years: OR = 3.6. 95% CI: 1.7-7.0, versus <50 years). The likelihood of inappropriateness also increased with each subsequent hospital day, culminating on the day of discharge, regardless of the total length of stay. Conclusions This study identified both the admission and the discharge processes as important sources of inappropriate hospital use in a department of internal medicine. The oldest patients were also at high risk of remaining in the hospital inappropriately. Surprisingly, long hospital stays did not generate a higher proportion of inappropriate days than short hospital stays. This information proved useful in developing interventions to improve the hospitalization proces

CODALEMA: a cosmic ray air shower radio detection experiment

International audienceThe CODALEMA experimental device currently detects and characterizes the radio contribution of cosmic ray air showers : arrival directions and electric field topologies of radio transient signals associated to cosmic rays are extracted from the antenna signals. The measured rate, about 1 event per day, corresponds to an energy threshold around 5.10$^{16}$eV. These results allow to determine the perspectives offered by the present experimental design for radiodetection of Ultra High Energy Cosmic Rays at a larger scale

Evidence for Radio Detection of Extensive Air Showers Induced by Ultra High Energy Cosmic Rays

Firm evidence for a radio emission counterpart of cosmic ray air showers is presented. By the use of an antenna array set up in coincidence with ground particle detectors, we find a collection of events for which both time and arrival direction coincidences between particle and radio signals are observed. The counting rate corresponds to shower energies $\gtrsim 5\times 10^{16}$ eV. These results open overwhelming perspectives to complete existing detection methods for the observation of ultra high-energy cosmic rays.Comment: 4 pages, 4 figure

Gas characterization based on a snapshot interferometric imaging spectrometer

International audienceModern atmospheric gas monitoring applications demand progressively better performances with regards to spatial, spectral and temporal resolutions. In this context, great potential is shown by a newly developed family of cutting-edge snapshot imaging spectrometers based on Fabry-Perot interferometry, whose conceptual design was patented under the name ImSPOC. Three different sensor prototypes based on the ImSPOC concept are under development: 1) in the near infrared wavelength range for CH4 or H2S detection, 2) in ultraviolet and visible range for NO2 , O4 , O3 and O2 characterisation and 3) specifically for CO2 monitoring. After the realisation of these prototypes there is the need arose to provide intelligible and well-calibrated acquisitions for the final users. This study presents the ImSPOC concept from the signal processing point of view, framing the optical transformations performed in the instruments under an appropriate mathematical model formulation. Additionally, preliminary developments are presented to address the first step of the signal processing pipeline for this instrument: the estimation of the thickness of each interferometer. This is a fundamental step for obtaining calibrated acquisitions that could then be used for gas monitoring

Features of radio-detected Extensive Air Shower with CODALEMA

International audienc

Features of radio-detected Extensive Air Shower with CODALEMA

International audienc

Features of radio-detected Extensive Air Shower with CODALEMA

International audienc

Features of radio detected Extensive Air Showers with CODALEMA

4 pages, 3 figures, proceeding des rencontres de l'astrophysique francaise, Strasbourg, 2005International audienceData acquisition and analysis for the CODALEMA experiment, in operation for more than one year, has provided improved knowledge of the characteristics of this new device. At the same time, an important effort has been made to develop processing techniques for extracting transient signals from data containing interference

Radiodetection signature of high-energy cosmic rays by the CODALEMA experiment

Taking advantage of recent technical progress which has overcome some of the difficulties encountered in the 1960’s in the radio detection of extensive air showers induced by ultra high energy cosmic rays (UHECR), a new experimental apparatus (CODALEMA) has been built and operated. We will present the characteristics of this device and the analysis techniques that have been developed for observing electrical transients associated with cosmic rays. We find a collection of events for which both time and arrival direction coincidences between particle and radio signals are observed. The counting rate corresponds to shower energies ≥ 5 × 10 16 eV. The performance level which has been reached considerably enlarges the perspectives for studying UHECR events using radio detection