1,906 research outputs found

    Recent Results from the RICE Experiment at the South Pole

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    We present a compilation of recent results, submitted to the 2003 International Cosmic Ray Conference (Tsukuba, Japan). These include: a) Revised Monte Carlo estimates of the radiofrequency signals produced by electromagnetic showers in ice, b) an updated search for ultra-high energy (UHE) neutrinos based on detection of radio-wavelength Cherenkov radiation; such radiation results from neutrino-induced electromagnetic showers in cold Polar ice, and c) An in situ measurement of the index of refraction through the South Polar firn.Comment: Compendium of RICE collaboration submissions to ICRC0

    Measurements of Radio Pulse Reception with Stations of the ARA Experiment based on the SpiceCore Pulser Data Set

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    The Askaryan Radio Array Experiment located near the South Pole works to pinpoint specific instances of neutrinos from outside the solar system interacting with nucleons inside the Antarctic ice. Neutrinos are a subatomic particle that has nearly no mass and a net neutral charge. As they are, neutrinos tend not to interact with anything as they travel through space which means they can provide us with information about events occurring far from Earth that might not be easily attained through other methods. Neutrinos are known to be emitted from a myriad of sources, including the Sun, the interaction between cosmic rays and the Earth’s atmosphere, supernovae and as cosmic neutrino background believed to be a result of the Big Bang. As the neutrinos pass through and interact with the ice, their collisions with nucleons will emit energy in the form of radio waves. ARA detectors measure these radio waves to determine the neutrino flux: how many neutrinos pass through a given area over a given time. Specifically, the ARA experiment aims to measure ultra-high energy (UHE) neutrinos with energies above 10^15 electron volts. These UHE neutrinos are predicted to directly originate from cosmological sources. The measurement of this flux would be useful as evidence proving/disproving existing physics theories that expect certain flux values. If the measured flux deviates considerably from theorized values, it could also stand as an indication of physical phenomena that are not currently known. Due to the bending of radio waves propagating close to the surface of the ice, a phenomenon occurring due to the dependence of the index of refraction on depth, radio waves are not able to propagate from certain regions of space to the receiving ARA stations, according to classical linear optics. It has been observed at ARA, however, that the classical picture is violated in practice. Although a shadow zone does exist, it is smaller than what theory predicts. In this UCARE project, I worked on mapping the shadow zones found in the Antarctic ice experimentally, using calibration data generated by a radio transmitter inside a hole made for the SpiceCore project, which was recorded by the ARA stations

    Polarization Angle Dependence of Vertically Propagating Radio-Frequency Signals in South Polar Ice

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    To better understand the effect of ice properties on the science reach of radio experiments designed to measure ultrahigh energy neutrinos (UHEN), we recently considered the timing and amplitude characteristics of radio-frequency (RF) signals propagating along multi-kilometer, primarily horizontal trajectories through cold Polar ice at the South Pole. That analysis indicated satisfactory agreement with a model of ice birefringence based on ice crystal (ĉ-axis) data culled from the South Pole Ice Core Experiment (SPICE). Here we explore the geometrically complementary case of signals propagating along primarily vertical trajectories, using extant data from the Askaryan Radio Array (ARA) experiment, supplemented by a refined analysis of older RICE experimental data. The timing characteristics of the South Polar data are in general agreement with the same birefringence model, although a several nanosecond discrepancy is found in comparison to Taylor Dome data. Re-analysis of older RICE data also confirm the correlation of signal amplitudes reflected from internal-layers with the direction of ice flow, similar to previous observations made along a traverse from Dome Fuji to the Antarctic coast. These results have two important implications for radio-based UHEN experiments: i) if birefringence can be locally calibrated, the timing characteristics of signals propagating from neutrino-ice interactions to a distant receiver might be used to infer the distance-to-vertex, which is necessary to estimate the energy of the progenitor neutrino, ii) the measured reflectivity of internal layers may result in previously-unanticipated backgrounds to UHEN searches, requiring significantly more modeling and analysis

    Protection of biological objects from electromagnetic radiation

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    The article deals with issues related to the impact of electromagnetic radiation (EMR) on humans and biological objects (bio-objects). Such types of radiation as electromagnetic fields of low frequency and microwave range, infrared and ultraviolet and ionizing radiation are considered. Data on the harmful effects of EMR on biological objects are given. The basic principles of protection against EMR are considered

    Comparison of Spider-Robot Information Models

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    The paper deduces a mathematical model of a spider-robot with six three-link limbs. Many limbs with a multi-link structure greatly complicate the process of synthesizing a model, since in total the robot has twenty-four degrees of freedom, i.e., three coordinates of the center of mass of the body in space, three angles of rotation of the body relative to its center of mass and three degrees of freedom for each limb, to describe the position of the links. The derived mathematical model is based on the Lagrange equations with a further transformation of the equations to the Cauchy normal form in a matrix form. To test the resulting model in a SimInTech environment, an information model is synthesized and two simple experiments ar carried out to simulate the behavior of real spiders: moving forward in a straight line and turning in place at a given angle. The experimental results demonstrate that the synthesized information model can well cope with the tasks and the mathematical model underlying it can be used for further research

    Search for New Physics with a Monojet and Missing Transverse Energy in pp Collisions at √s= 7 TeV

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    A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a center-of-mass energy of 7 TeV. The data were collected by the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb-1. An excess of these events over standard model contributions is a signature of new physics such as large extra dimensions and unparticles. The number of observed events is in good agreement with the prediction of the standard model, and significant extension of the current limits on parameters of new physics benchmark models is achieved

    Search for New Physics with a Monojet and Missing Transverse Energy in pp Collisions at √s= 7 TeV

    Get PDF
    A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a center-of-mass energy of 7 TeV. The data were collected by the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb-1. An excess of these events over standard model contributions is a signature of new physics such as large extra dimensions and unparticles. The number of observed events is in good agreement with the prediction of the standard model, and significant extension of the current limits on parameters of new physics benchmark models is achieved
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