6,789 research outputs found

    Rocket experiments for spectral estimation of electron density fine structure in the auroral and equatorial ionosphere and preliminary results

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    Sounding rockets equipped to monitor electron density and its fine structure were launched into the auroral and equatorial ionosphere in 1980 and 1983, respectively. The measurement electronics are based on the Langmuir probe and are described in detail. An approach to the spectral analysis of the density irregularities is addressed and a software algorithm implementing the approach is given. Preliminary results of the analysis are presented

    First Results from the HDMS experiment in the Final Setup

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    The Heidelberg Dark Matter Search (HDMS) is an experiment designed for the search for WIMP dark matter. It is using a special configuration of Ge detectors, to efficiently reduce the background in the low-energy region below 100 keV. After one year of running the HDMS detector prototype in the Gran Sasso Underground Laboratory, the inner crystal of the detector has been replaced with a HPGe crystal of enriched 73^{73}Ge. The final setup started data taking in Gran Sasso in August 2000. The performance and the first results of the measurement with the final setup are discussed.Comment: 8 pages, revtex, 7 figures, Home Page of Heidelberg Non-Accelerator Particle Physics Group: http://www.mpi-hd.mpg.de/non_acc

    A case of post–traumatic cervicogenic headache treated by cervical cord stimulation

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    The case of a 26–year–old woman suffering from cervical trauma with disc herniation presenting with arm and neck pain is presented. She underwent cervical discectomy with fusion because the pain did not improve with medical therapies; as the neck pain resumed after surgery, a cervical cord neurostimulator was implanted, with improvement for cervicogenic headache. This report underlines the presence of two pathologies and the relationship between C2 and trigeminal pathways

    Measurements and optimization of the light yield of a TeO2_2 crystal

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    Bolometers have proven to be good instruments to search for rare processes because of their excellent energy resolution and their extremely low intrinsic background. In this kind of detectors, the capability of discriminating alpha particles from electrons represents an important aspect for the background reduction. One possibility for obtaining such a discrimination is provided by the detection of the Cherenkov light which, at the low energies of the natural radioactivity, is only emitted by electrons. This paper describes the method developed to evaluate the amount of light produced by a crystal of TeO2_2 when hit by a 511 keV photon. The experimental measurements and the results of a detailed simulation of the crystal and the readout system are shown and compared. A light yield of about 52 Cherenkov photons per deposited MeV was measured. The effect of wrapping the crystal with a PTFE layer, with the aim of maximizing the light collection, is also presented

    The vulnerability of refrigerated food to unstable power supplies

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    This paper describes a simplified model for estimating the vulnerability to spoilage of a number of refrigerated foods in households, resulting from interruptions to the electricity power grid. The tool is demonstrated on a sample of three foods (milk, chicken and fish) in India, which historically has suffered significant interruptions. The effect of interruptions is quantified in terms of tonnage and monetary value of potential losses, in a number of simple scenarios. These losses are estimated for rural and urban areas of each Indian state. Our model indicates that extensions to the duration of power supply interruptions increases potential losses in domestic refrigerators, and that these losses are considerable when compared to losses expected in previous stages of the food supply chain. The current model’s estimation of weight of food lost may be converted to a nutritional value, which opens an opportunity for new multidisciplinary areas of research

    Mense e personale addetto alle cucine: valutazione dei rischi occupazionali

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    The aim of the study is to evaluate the occupational risks among food service workers and cooks. During the occupational risks assessment the following risk factors must be evaluated: musculoskeletal disorders, chemical risk (cleaning kitchen work surface, dishes, utensils ecc.) biological risk (contact with foods or biological agents) cancerogenic risk (by baking smoke inhalation), and psycho-social stress. In this study the preventive measures and protective equipment to prevent health hazards for these workers have been evaluated (i.e. aspiration hood, adapted ventilation, chosen of less harmful methods of baking, ecc.). In particular the performance of rigid behavioural norms and hygienic procedures is very important for cooks and food service workers to reduce the risk of occupational infections

    New application of superconductors: high sensitivity cryogenic light detectors

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    In this paper we describe the current status of the CALDER project, which is developing ultra-sensitive light detectors based on superconductors for cryogenic applications. When we apply an AC current to a superconductor, the Cooper pairs oscillate and acquire kinetic inductance, that can be measured by inserting the superconductor in a LC circuit with high merit factor. Interactions in the superconductor can break the Cooper pairs, causing sizable variations in the kinetic inductance and, thus, in the response of the LC circuit. The continuous monitoring of the amplitude and frequency modulation allows to reconstruct the incident energy with excellent sensitivity. This concept is at the basis of Kinetic Inductance Detectors (KIDs), that are characterized by natural aptitude to multiplexed read-out (several sensors can be tuned to different resonant frequencies and coupled to the same line), resolution of few eV, stable behavior over a wide temperature range, and ease in fabrication. We present the results obtained by the CALDER collaboration with 2x2 cm2 substrates sampled by 1 or 4 Aluminum KIDs. We show that the performances of the first prototypes are already competitive with those of other commonly used light detectors, and we discuss the strategies for a further improvement

    Characterization of the KID-Based Light Detectors of CALDER

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    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5×55\times5 cm2^2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0-30 keV

    Energy resolution and efficiency of phonon-mediated Kinetic Inductance Detectors for light detection

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    The development of sensitive cryogenic light detectors is of primary interest for bolometric experiments searching for rare events like dark matter interactions or neutrino-less double beta decay. Thanks to their good energy resolution and the natural multiplexed read-out, Kinetic Inductance Detectors (KIDs) are particularly suitable for this purpose. To efficiently couple KIDs-based light detectors to the large crystals used by the most advanced bolometric detectors, active surfaces of several cm2^2 are needed. For this reason, we are developing phonon-mediated detectors. In this paper we present the results obtained with a prototype consisting of four 40 nm thick aluminum resonators patterned on a 2×\times2 cm2^2 silicon chip, and calibrated with optical pulses and X-rays. The detector features a noise resolution σE=154±7\sigma_E=154\pm7 eV and an (18±\pm2)%\% efficiency.Comment: 5 pages, 5 figure
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