Status and First Results of the Acoustic Detection Test System AMADEUS

The AMADEUS system is integrated in the ANTARES neutrino telescope in the Mediterranean Sea and aims for the investigation of acoustic particle detection techniques in the deep sea. Installed at a depth of more than 2000m, the acoustic sensors of AMADEUS are using piezo-ceramic elements for the broad-band recording of acoustic signals with frequencies ranging up to 125kHz. AMADEUS consists of six clusters, each one comprising six acoustic sensors that are arranged at distances of roughly 1m from each other. Three acoustic clusters are installed along a vertical mechanical structure (a so-called Line) of ANTARES with spacings of about 15m and 110m, respectively. The remaining 3 clusters are installed with vertical spacings of 15m on a further Line of the ANTARES detector. The horizontal distance between the two lines is 240m. Each acoustic cluster allows for the suppression of random noise by requiring local coincidences and the reconstruction of the arrival direction of acoustic waves. Source positions can then be reconstructed using the precise time correlations between the clusters provided by the ANTARES clock system. AMADEUS thus allows for extensive acoustic background studies including signal correlations on several length scales as well as source localisation. The system is therefore excellently suited for feasibility studies for a potential future large scale acoustic neutrino telescope in sea water. Since the start of data taking on December 5th, 2007 a wealth of data has been recorded. The AMADEUS system will be described and some first results will be presented.Comment: Proceedings of the ARENA 2008 workshop (http://www.roma1.infn.it/arena2008/), June 2008. 8 pages, 10 figure

Deep-Sea Acoustic Neutrino Detection and the AMADEUS System as a Multi-Purpose Acoustic Array

The use of conventional neutrino telescope methods and technology for detecting neutrinos with energies above 1 EeV from astrophysical sources would be prohibitively expensive and may turn out to be technically not feasible. Acoustic detection is a promising alternative for future deep-sea neutrino telescopes operating in this energy regime. It utilises the effect that the energy deposit of the particle cascade evolving from a neutrino interaction in water generates a coherently emitted sound wave with frequency components in the range between about 1 and 50 kHz. The AMADEUS (Antares Modules for Acoustic DEtection Under the Sea) project is integrated into the ANTARES neutrino telescope and aims at the investigation of techniques for acoustic particle detection in sea water. The acoustic sensors of AMADEUS are using piezo elements and are recording a broad-band signal with frequencies ranging up to 125 kHz. After an introduction to acoustic neutrino detection it will be shown how an acoustic array similar to AMADEUS can be used for positioning as well as acoustic particle detection. Experience from AMADEUS and possibilities for a future large scale neutrino telescope in the Mediterranean Sea will be discussed.Comment: Proceedings of the VLVnT08 workshop (http://marwww.in2p3.fr/VLVnT08/), April 200

Attenuation of acoustic waves in glacial ice and salt domes

Two classes of natural solid media (glacial ice and salt domes) are under consideration as media in which to deploy instruments for detection of neutrinos with energy >1e18 eV. Though insensitive to 1e11 to 1e16 eV neutrinos for which observatories (e.g., AMANDA and IceCube) that utilize optical Cherenkov radiation detectors are designed, radio and acoustic methods are suited for searches for the very low fluxes of neutrinos with energies >1017 eV. This is because, due to the very long attenuation lengths of radio and acoustic waves in ice and salt, detection modules can be spaced very far apart. In this paper, I calculate the absorption and scattering coefficients as a function of frequency and grain size for acoustic waves in glacial ice and salt domes and show that experimental measurements on laboratory samples and in glacial ice and salt domes are consistent with theory. For South Pole ice with grain size 0.2 cm at -51 degrees C, scattering lengths are calculated to be 2000 km and 25 km at 10 kHz and 30 kHz, respectively, and the absorption length is calculated to be 9 km at frequencies above 100 Hz. For NaCl (rock salt) with grain size 0.75 cm, scattering lengths are calculated to be 120 km and 1.4 km at 10 kHz and 30 kHz, and absorption lengths are calculated to be 30,000 km and 3300 km at 10 kHz and 30 kHz. Existing measurements are consistent with theory. For ice, absorption is the limiting factor; for salt, scattering is the limiting factor.Comment: 16 pages, 7 figures, submitted to Journal of Geophysical Research - Solid Eart

Underwater Acoustic Detection of Ultra High Energy Neutrinos

We investigate the acoustic detection method of 10^18-20 eV neutrinos in a Mediterranean Sea environment. The acoustic signal is re-evaluated according to dedicated cascade simulations and a complex phase dependant absorption model, and compared to previous studies. We detail the evolution of the acoustic signal as function of the primary shower characteristics and of the acoustic propagation range. The effective volume of detection for a single hydrophone is given taking into account the limitations due to sea bed and surface boundaries as well as refraction effects. For this 'benchmark detector' we present sensitivity limits to astrophysical neutrino fluxes, from which sensitivity bounds for a larger acoustic detector can be derived. Results suggest that with a limited instrumentation the acoustic method would be more efficient at extreme energies, above 10^20 eV.Comment: 15 pages, 11 figure

Development of Acoustic Sensors for the ANTARES Experiment

In order to study the possibility of acoustic detection of ultra-high energy neutrinos in water, our group is planning to deploy and operate an array of acoustic sensors using the ANTARES Neutrino telescope in the Mediterranean Sea. Therefore, acoustic sensor hardware has to be developed which is both capable of operation under the hostile conditions of the deep sea and at the same time provides the high sensitivity necessary to detect the weak pressure signals resulting from the neutrino's interaction in water. In this paper, two different approaches to building such sensors, as well as performance studies in the laboratory and in situ, are presented.Comment: 5 pages, 3 figures. Proceedings of the ARENA 2005 Worksho

Testing Thermo-acoustic Sound Generation in Water with Proton and Laser Beams

Experiments were performed at a proton accelerator and an infrared laser acility to investigate the sound generation caused by the energy deposition of pulsed particle and laser beams in water. The beams with an energy range of 1 PeV to 400 PeV per proton beam spill and up to 10 EeV for the laser pulse were dumped into a water volume and the resulting acoustic signals were recorded with pressure sensitive sensors. Measurements were performed at varying pulse energies, sensor positions, beam diameters and temperatures. The data is well described by simulations based on the thermo-acoustic model. This implies that the primary mechanism for sound generation by the energy deposition of particles propagating in water is the local heating of the media giving rise to an expansion or contraction of the medium resulting in a pressure pulse with bipolar shape. A possible application of this effect would be the acoustical detection of neutrinos with energies greater than 1 EeV.Comment: 5 pages, 2 figures, to appear in the proceedings of the 1st International ARENA Workshop, May 17-19th, 2005, DESY Zeuthe

A compact acoustic calibrator for ultra-high energy neutrino detection

With the aim to optimize and test the method of acoustic detection of ultra-high energy neutrinos in underwater telescopes a compact acoustic transmitter array has been developed. The acoustic parametric effect is used to reproduce the acoustic signature of an ultra-high-energy neutrino interaction. Different R&D studies are presented in order to show the viability of the parametric sources technique to deal with the difficulties of the acoustic signal generation: a very directive transient bipolar signal with 'pancake' directivity. The design, construction and characterization of the prototype are described, including simulation of the propagation of an experimental signal, measured in a pool, over a distance of 1 km. Following these studies, next steps will be testing the device in situ, in underwater neutrino telescope, or from a vessel in a sea campaign. (c) 2012 Elsevier B.V. All rights reserved.This work has been supported by the Ministerio de Ciencia e Innovacion (Spanish Government), project references FPA2009-13983-C02-02, ACI2009-1067, Consolider-Ingenio Multidark (CSD2009-00064). It has also been funded by Generalitat Valenciana, Prometeo/2009/26.Adrián Martínez, S.; Ardid Ramírez, M.; Bou Cabo, M.; Larosa, G.; Llorens Alvarez, CD.; Martínez Mora, JA. (2013). A compact acoustic calibrator for ultra-high energy neutrino detection. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 725:219-222. https://doi.org/10.1016/j.nima.2012.11.142S21922272

Risk Factors of Nasal Carriage of Methicillin-Resistant Staphylococcus Aureus and its Antibiotic Susceptibility Pattern in Namazi Hospital Healthcare Workers in Shiraz, Iran

Abstract: Background & Aims: Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide. The aim of this study was to determine the risk factors of nasal carriage of MRSA and its antibiotic susceptibility pattern among healthcare workers at Namazi Hospital (Shiraz-Iran) Methods: In a cross-sectional study from July to November 2006, nasal swabs were taken from 600 stratified randomly selected health care workers. The isolates were identified as S. aureus based on morphology, gram stains, catalase test, coauglase test and DNase Agar. To differentiate Methicillinsusceptible S. aureus (MSSA) and Methicillin Resistant S. aureus (MRSA), agar screen plate was used. All methicillin-resistant isolates were examined for mecA genes existence by PCR performance. The sensitivity patterns of S.aureus isolates were determined by disc diffusion and E-test method. Results: Nasal screening identified 186 (31%) S. aureus carriers of whom, 154 ones (82.8%) were MSSA and 32 ones (17.2%) were MRSA._There was no significant association between related risk factors and gender, age, years of healthcare service and level of education. In the univariate analysis, a statistically significant difference was found only based on occupation (P=0.032) between carriers of MSSA and MRSA. In multivariate analysis(logistic regression), having nursing occupation (p=0.012, OR=3.6, 95%CI=1.3-9.7) was independently associated with MRSA carriage. All of the MRSA strains were sensitive to mupirocin. Conclusion: This study revealed that having nursing occupation is independently associated with MRSA carriage since all S.aureus isolates were susceptible to mupirocin, topical mupirocin could be used successfully to eradicate nasal staphylococcal colonization and carriers. Keywords: Staphylococcus aureus, Methicillin, Risk factors, Carrier, Microbial sensitivity, Health care provider

Protective Effect of Zizphus Vulgaris Extract, on Liver Toxicity in Laboratory Rats

Introduction & Objective: Some of natural and synthetic products have antioxidant properties which protect the liver against the destructive factors. This study aimed to investigate the effect of Zizphus Vulgaris extracts on mice liver. Materials & Methods: This experimental study was conducted at Yasouj University of Medical Sciences in 2010 on 30 healthy adult male Wistar rats. Animals were randomly divided into five equal groups: the control group (receiving, olive oil), control group (receiving olive oil and carbon tetrachloride and three intervention groups (receiving different dose of carbon tetrachloride and olive oil) groups. The intervention group was given daily doses of 200, 400 and 600 mg per Kg of Zizphus Vulgaris extract by gavage respectively. After 45 days, the amount of liver enzymes, total protein, albumin and bilirubin in animal’s sera were measured. Data were analyzed by the SPSS software, using ANOVA and t-test. Results: The concentration of total protein, albumin, AST, ALT, ALP in test groups I, II and III receiving Z.Vulgaris extract (200, 400 and 600 mg/kg weight) compared with control group were statistically not significant. Consumption of Z.Vulgaris reduced the bilirubin concentration in test groups I and II but this decrease was significant only in the test group I Increasing of Z.Vulgaris dose in the test group III (600 mg Z.Vulgaris per kg body weight) showed increase in the level of serum bilirubin. Increase in the ratio of liver weight to body weight of rats in groups I and III in comparison with control groups was noticed although this difference was not statistically significant. Findings of this study revealed that dosage of 600 mg/kg extract of Z.Vulgaris caused significant improvements in CCl4 induced liver necrosis (P <0.01) and reduced portal cells inflammation (P <0.01). Dose of 400 mg/kg of Z.Vulgaris induced some destruction and necrosis of liver cells in animals but significant reduction of portal cells inflammation was seen. Conclusion: Considering the obtained results, it seems that Ziziphus vulgaris fruit extract has shielding effects against toxins on liver cells