Abstracts
Optimal Radio Window for the Detection of Ultra-High-Energy Cosmic Rays and Neutrinos
O. Scholten, J. Bacelar, R. Braun, A.G. de Bruyn, H. Falcke, B. Stappers, R.G. StromWhen high-energy cosmic rays impinge on a dense dielectric medium, radio waves are produced through the Askaryan effect. We show that at wavelengths comparable to the length of the shower produced by an Ultra-High Energy cosmic ray or neutrino, radio signals are an extremely efficient way to detect these particles. Through an example it is shown that this new approach offers, for the first time, the realistic possibility to measure UHE neutrino fluxes below the Waxman-Bahcall limit using an existing facility. It is shown that in only one month of observation with the upcoming LOFAR radio telescope, cosmic-ray events can be measured beyond the GZK-limit, at a flux level of three orders of magnitude below that of the highest-energy events ever measured.
Status of Hawaii Askaryan in Salt Radio Array (HASRA) Experiment
Radovan MilincicThe exploration of GZK neutrinos through their interactions with matter via produced radio signals requires highly homogeneous material with small attenuation for radio frequencies. Rock salt in some salt dome formations provide dielectric material with great potential to host a large scale (100 Km^3) water-equivalent ultra-high energy neutrino detector. The Hawaii Askaryan in Salt Radio Array (HASRA) detector was built as a testbed for exploration of coherent radio Cherenkov emission in salt from interaction of cosmic ray induced cascades. We report results of 1 year of measurements of Askaryan effect with HASRA detector. Performance of the detector, its sensitivity and analysis of a newest data set will be presented.
Results from the RICE experiment at the South Pole
D. BessonWe discuss results on the UHE neutrino flux using the radio cherenkov technique at the South Pole. Limits on the diffuse UHE neutrino flux, searches for coincidences with Gamma-Ray Bursts, and searches for highly ionizing particles (monopoles) will be discussed.
Retrofitted IceCube Modules for Radio Detection in Ice
Dawn WilliamsIn the 2006/2007 polar season, the radio detection work previously carried out by the RICE collaboration at the South Pole will be expanded by co-deployment in IceCube holes. The antennas will be read out using a Digital Radio Module (DRM), a retrofitted IceCube module. The DRM digitizes radio waveforms in the ice and uses the existing IceCube architecture to move data to the surface. I will describe the DRM hardware, triggering algorithms, and surface data acquisition.
Air Shower Radio Measurements of Distant Events with LOPES
Andreas Haungs for the LOPES CollaborationLOPES is set up at the location of the KASCADE-Grande extensive air shower experiment in Karlsruhe, Germany and aims to measure and calibrate radio pulses from Extensive Air Showers (EAS). LOPES is designed as a digital radio interferometer using high bandwidths and fast data processing and profits from the reconstructed air shower observables of KASCADE-Grande. Data taken during half a year of operation of 10 LOPES antennas (LOPES-10), triggered by EAS observed with KASCADE-Grande have been analysed.
We report about the analysis of correlations present in the radio signals measured by LOPES-10 with cores at large distances. The efficiency of detecting radio signals induced by air showers up to distances of 700m from the shower axis has been investigated. The results are discussed with special emphasis on the effects of the reconstruction accuracy for shower core and arrival direction on the coherence of the measured radio signal. In addition, the correlations of the radio pulse amplitude with the primary cosmic ray energy and with the lateral distance from the shower core are studied.
Status and Perspectives of the LOPES experiment at KASCADE-Grande
Andreas Haungs for the LOPES CollaborationThe detection of radio pulses emitted in the atmosphere during the air shower development of high-energy primary cosmic rays is the task of the LOPES project. LOPES is set up to operate in conjunction with an existing air shower experiment (KASCADE-Grande) and consists of 30 LOFAR- type antennas (LOPES-30) which are calibrated using a reference radio source resulting in amplification factors representing the system behaviour in the environment of the KASCADE-Grande experiment.
Additionally, LOPES operates antennas of a different type (LOPES-STAR) which are optimized for an application at the Pierre Auger Observatory. Status and perspectives as well as first results of LOPES will be presented.
Measurement of attenuation length for radio wave in natural rock salt and the performance of detecting ultra high energy neutrinos
Masami ChibaAttenuation length of natural rock salts are measured at 0.3 and 1.0GHz. Some show a longer attenuation length than 300m. We simulated the performance of detecting GZK neutrinos using the attenuation length. We find the GZK event rate is 8-62/year in a 3km x 3km x 3km salt neutrino detector.
Status of the ANITA Experiment
Stephen Hoover for the ANITA CollaborationANITA is a NASA-sponsored long-duration balloon experiment designed to detect radio Cherenkov from particle showers initiated by UHE neutrinos in the Antarctic ice. ANITA is scheduled to fly during this Antarctic summer (Dec 2006 - Jan 2007). We present an overview of the ANITA experiment and its goals. We will also give an update on the experiment's current status. Milestones in the past year include an engineering flight in August 2005 and a beamtest using an ice target at SLAC in June 2006.
Investigation of acoustic phenomena from extensive atmospheric showers
Vladimir LyashukInvestigation of acoustic effects from extensive atmospheric showers was carried out in the expeditions to Baikal from 2001 year. The registration was realized in the trigger scheme of sound files recording when atmospheric showers were detected by the scintillation installation. Two methods were proposed for search of weak acoustic effects: 1) the method of peaks and noncoincidences (an algorithm of the method is amplitude independent) and 2) the method of small peaks. In processing of a great body of data it were revealed the analogous phenomena at the instant of time of expected sound signals from showers. The results (which were obtained at different geometries and different noise background) indicate on the registration of the acoustic effects from extensive atmospheric showers.
Acoustic Signal Computations in the Mediterranean Sea
V. Bertin, V. NiessWe investigated the acoustic detection method of 10^{18-20} eV neutrinos in a Mediterranean Sea environment. The acoustic signal was 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. Estimations for the effective volume of detection for a single hydrophone are 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.
SPATS- Calibration and outdoor lake test
S. Böser, C. Bohm, F. Descamps, J. Fischer , A. Hallgren,R. Heller, S. Hundertmark, K. Krieger, R. Nahnhauer, M. Pohl, P. B. Price, K. Sulanke, J. VandenbrouckeThe South Pole Acoustic Test Setup (SPATS) will be installed in the polar season 06/07 after which the collected data will be used to reveal the acoustic properties of the south polar ice cap. The developed piezoceramic based ultrasound sensors and transmitters that are part of this system have been extensively studied during calibration measurements in water, using a commercial hydrophone as reference. Also, a SPATS system test was recently accomplished in Lake Tornetrask, Abisko (Sweden). This allowed verification of ,for instance ,the DAQ system and transmitter range. Results of the calibrations and the Abisko lake measurement will be presented.
Geosynchrotron radio emission from CORSIKA-simulated air showers
T. Huege, R. Ulrich, R. EngelThe simulations of radio emission from extensive air showers we have published so far were performed with a Monte Carlo code using analytical parametrisations to describe the spatial, temporal, energetical and angular particle distributions in the air shower. A new version of our simulation code which replaces these parametrisations with precise, multi-dimensional histograms derived from per-shower CORSIKA simulations, is now available. The new code allows for an independent selection between parametrisation and histogram for each of the relevant distributions, enabling us to study the changes arising from the more realistic air shower model in detail. I will describe the new simulation strategy, present some initial results and discuss the new possibilities arising.
Status of the South Pole Acoustic Test Setup
S. Böser for the SPATS Group: S.Boser, C. Bohm, F. Descamps, J. Fischer, A. Hallgren, R. Heller, S. Hundertmark, K. Krieger, R. Nahnhauer, M. Pohl, P. B. Price, K. Sulanke, J. VandenbrouckeAcoustic detection of ultra high energy cascades via the thermoacoustic effect in the antarctic ice sheet seems to be promising due to the large expected absorption and scattering length. Simulations of a ~100 km^3 hybrid detector yield rates of ~10 events per year from neutrinos generated by interactions of highest energy cosmic rays with the cosmic microwave background (GZK effect), which is considered a 'guaranteed' flux at these energies. Apart from the properties of the glaciophones, which were modeled according to recent developements, the main uncertainty in the simulation comes from the acoustic properties of the south polar ice itself, which have only been theoretically derived so far. The South Pole Acoustic Test Setup has been created to measure absorption, refraction and background noise in situ at South Pole. The status of the project and results of various system verification tests will be reported.
AURA: The Askaryan Underice Radio Array
Kara Hoffman for the AURA CollaborationThe abundant cold ice covering the Antarctic provides a tantalizing medium for detecting ultra high energy neutrinos due to it's excellent rf transparency, as characterized by RICE, a first generation radio array buried between 100 and 300 m near the geographic South Pole. However, an array large enough to be sensitive to the low flux of neutrinos at UHE would have to overcome the technical challenges associated with designing and operating a sparse array in a hostile environment, including power distribution, time calibration, triggering and readout over a scale of kilometers in temperatures of -50 C and pressures that can reach hundreds of atmospheres during freeze-in. The IceCube Collaboration faced similar challenges in engineering a kilometer cubed optical Cherenkov array. IceCube is now more than 10% complete and is successfully taking data in the deep ice near the Pole. The novel technologies contained within IceCube's digital optical module may be retrofitted, at low cost, for radio. Further, clusters of radio antennas could be installed parasitically on IceCube's cables, with minimal impact on IceCube's deployment operations. In the coming austral summer, the AURA collaboration will begin co-deploying antenna clusters with IceCube strings, as a prelude to a 100 kilometer scale array.
Measurement and simulation studies of piezoceramics for acoustic particle detection
K. Salomon, Anton, Deffner, Graf, Hössl, Kappes, Katz, Lahmann, Naumann, RichardThe standard sensitive elements for acoustic sensors are piezo active elements, e.g. piezoceramics. We calculate the mechanical and electrical behaviour of these piezoceramics using finite element simulations and proof the calculations with measurements. The mechanical properties at the surface of the sensors, the displacement, are needed in order to calculate the pressure produced by these sensors when used as acoustic transmitters. On the other side the electrical properties are needed to know the impedance matching needed to design preamplifiers for receivers. Furthermore the coupling of these sensors to water is simulated. To minimize calculation time non reflecting surface conditions are implemented in the calculations.
Calibration of Sensors for Acoustic Detection of Neutrinos
M. Ardid, M. Bou-Cabo, V. Espinosa, J. Ramis, J. Redondo, J. Martínez-Mora, F. Camarena, J. Alba, V. Sánchez-MorcilloCalibration of sensors is an important task for the acoustic detection of neutrinos. Different approaches have been tried and used (calibrated hydrophones, resistors, powerful lasers, light bulbs explosion, etc.) We propose some methods for calibration that can be used in both the lab and the telescope ("in situ"). In this communication, different studies following these methods and their results are reported. First, we describe the reciprocity calibration method for acoustic sensors. Since it is a simple method and calibrated hydrophones are not needed, this technique is accessible for any lab. Moreover, the technique could be used to calibrate the sensors of a neutrino telescope just by using themselves (reciprocally). A comparison of this technique using different kind of signals (tone bursts, MLS, TSP, white noise), and in different propagation conditions is presented. The limitations of the technique are shown, as well as some possibilities to overcome them. The second aspect treated is the obtaining of neutrino-like signals for calibration. Probably, the most convenient would be to generate these signals from transducers directly. Since transducers do not usually have a flat frequency response, distortion is produced, and neutrino-like signals could be difficult to achieve. We present some equalization techniques to offset this effect. In this sense, the use of inverse filter based in Mourjopoulos theory seems to be quite convenient.
Novel micro-pixel avalanche photodiodes and their possible application in physical/astrophysical researches
Z.Ya. Sadygov (JINR, Dubna) and I.M. Zheleznykh (INR, Moscow)Discussions on the production and use of avalanche photodiodes (APDs) as solid state analogs of the photo multiplier tubes (PMTs) in DUMAND-type experiments had started in INR in 1978. In 80th a new type of APDs with negative local feedback the metal-resistive layer-semiconductor (MRS) APDs - was developed in INR by Sadygov et al. in the frameworks of the Soviet DUMAND program led by M.A. Markov. In 90th and during the last few years some new kinds of the Micro-channel/pixel Avalanche PhotoDiodes (M-APDs), which have high signal gain, high photon detection efficiency, very good single electron resolution, were developed in INR and JINR. In this report characteristics of the novel M-APDs which were constructed, produced and tested by -Dubna APD - collaboration (JINR - INR - PSI - IP AZ "Micron" factory) are described. Prospects for using the M-APDs in different fields of Physics and Astrophysics are also discussed.
Deriving the performance of piezoelectric sensors from electromechanical properties
Christopher NaumannThe ANTARES collaboration is currently installing a neutrino telescope off the french mediterranean coast to measure diffuse fluxes and point sources of high energy cosmic neutrinos. The complete detector will consist of 900 photomultipliers on 12 detector lines, using 0.01km of sea water as target material. As part of the ANTARES deep-sea research infrastructure, the Erlangen group is planning to modify several ANTARES storeys by fitting them with acoustic receivers to study the feasibility of acoustic neutrino detection in the deep sea.
In this presentation, studies of the electromechanical properties of piezoelectric sensors are presented, based on an equivalent circuit diagram for the coupled mechanical and electrical oscillations of a piezoelectric element. A method for obtaining the system parameters as well as derivations of sensor properties like pressure sensitivity and intrinsic noise are treated and results compared to measurements. Finally, a possible application of these results for simulating system response and optimising reconstruction algorithms is discussed.
Simulating the Sensitivity of hypothetical km^3 hydrophone arrays to fluxes of UHE neutrinos
Jonathan Perkin (on behalf of the ACoRNE collaboration)Modifications have been made to the existing ACoRNE sensitivity code that incorporate the effects of refraction due to depth dependent sound velocity. In the presence of refraction, no analytical solution exists for reconstruction of point sources from the signal arrival times. Algorithms for vertex reconstruction using linear interpolation methods will be discussed as will progress with respects to energy reconstruction and pointing resolution. A framework for incorporating EeV neutrino induced hadronic showers, independent of parameterisations, will be introduced. This is achieved through the utilisation of an ACoRNE extension to the CORSIKA toolkit.
Integration of Acoustic Neutrino Detection Methods into ANTARES
K. Graf; G. Anton, J. Hößl, A. Kappes, U. Katz, R. Lahmann, C. Naumann, K. SalomonThe ANTARES Neutrino Telescope is a 0.01km³-scale water Cherenkov detector currently under construction in the Mediterranean Sea. It is also designed to serve as platform for the investigation of the deep-sea environment. In this context, the ANTARES group at the University of Erlangen is working towards the integration of acoustic sensors within the infrastructure of the experiment. With this dedicated setup, tests of acoustic particle detection methods and deep-sea background studies shall be performed. This talk will highlight the aims and the implementation of this project and the research in the field of acoustic detection leading to this setup. The focus will be on the technical realisation, which is governed by the premises and challenges set by the physics of acoustic particle detection and the integration into an existing infrastructure.
Acoustic Measurements in ANTARES: Status and Aim
Robert Lahmann et al.The installation of the ANTARES Neutrino Telescope in the Mediterranean Sea is currently being pursued. The first of a total of 12 mechanical structures (strings) holding photomultipliers has been deployed to date with completion being foreseen by the end of 2007. In the first half of 2007, after roughly half of the strings will have been deployed, a set of acoustic sensors will be incorporated into the ANTARES Detector. The aim of this setup is to develop acoustic particle detection methods and study deepsea background. In this talk, acoustic detection within the ANTARES Detector will be discussed, with special attention to the implications of the detector design and the time schedules of the ANTARES project for the acoustic measurements.
Status of SalSA
Amy ConnollyThe Salt Sensor Array (SalSA) is a proposed experiment that would deploy antennas in a large, naturally occuring salt formation with the aim to detect a sample of neutrinos in the ultra-high energy regime with the radio Cherenkov technique. I will discuss progress that has been made in selecting a site for the SalSA experiment, including recent developments regarding the possibility of deploying antennas in a salt mine. From simulations, I will present the expected sensitivity of a SalSA deployed in a mine compared to the one deployed in boreholes drilled from the surface. I will also discuss a recent trip to the Cote Blanche mine to measure attenuation lengths through salt.
Reconstruction Algorithms for UHE Neutrino Events in Sea Water
Simon BevanThis talk will focus on the techniques currently employed to reconstruct the vertex position of an event as detected by hydrophones in the RONA array.
Simulating Neutrino Interactions with CORSIKA
Terry SloanSimulations of interactions in water have been made with the shower program CORSIKA. The generation of neutrino showers will be described.
Results from the NEMO Test Site
Giorgio RiccobeneIn January 2005 the NEMO Collaboration installed at the NEMO Test Site location (25 km offshore the port of Catania, 2000 m depth) the underwater station ONDE to measure acoustic background at large depth. The station is equipped with 4 hydrophones operational in the range 30 Hz - 40 kHz. About one year of data have been acquired. The first results on noise level and variations as a function of time will be presented. Classification and tracking of transient signals is under way.
