Feasibility of acoustic neutrino detection with the South Pole Acoustic Test Setup

Current experiments in astroparticle physics span over more than 13 orders of magnitude in energy and 28 orders of magnitude in flux. They make use of the detection of all types of messengers in order to learn more about the sources of these cosmic rays, the properties of the interstellar medium, as well as the nature of the particles themselves. The feeble interaction of neutrinos with matter makes them uniquely valuable as astronomical messengers. Unlike photons or charged particles, neutrinos can emerge from deep inside their sources and travel across the universe without interference.However, this same trait makes cosmic neutrinos extremely difficult to detect. Immense instruments, using natural resources as detector medium, are required to find them in sufficient numbers. Antarctic polar ice has turned out to be an ideal medium for detecting neutrinos. It is exceptionally pure, transparent and free of radioactivity. The density of detectors in such large neutrino telescopes is dictated by the attenuation length of the observable signal that is generated by the neutrino interaction with the medium. The optically transparent ice at the geographic South Pole has optical attenuation lengths in the order of 100m. This has allowed the construction and operation of the kilometer-scale neutrino detector, IceCube. However, the optical attenuation length and therefore detector cost is prohibitive to a possible extension towards the even larger detector volumes that are needed to detect the astrophysical neutrinos of the highest energies. Both the attenuation length of radio and acoustic waves are predicted to be larger than 1km in ice and both signatures are generated in an UHE neutrino interaction. Hence, this interaction in ice could be detected by an hybrid detector array consisting of optical, radio and acoustic sensors. The aim of presented work is to investigate the feasibility of an acoustic neutrino detection array situated in th South Polar ice. To this end, the acoustic properties of the ice in the 1 to 100kHz region were measured with a dedicated acoustic test setup:the South Pole Acoustic Test Setup (SPATS). The SPATS measurement of the acoustic attenuation length of the Antarctic ice using inter-string data is presented. This attenuation length is a fundamental quantity in determining the design and sensitivity of a future acoustic neutrino detector at South Pole

Measurement of sound speed versus depth in Antarctic ice with the South Pole Acoustic Test Setup

The feasibility and design of an acoustic neutrino detection array in the South Pole ice depend on the acoustic properties of the ice. The South Pole Acoustic Test Setup (SPATS) was built to evaluate the acoustic characteristics of the ice in the 1 to 100kHz frequency range. The vertical sound speed profile relates to the level of refraction of the surface noise and determines the reconstruction precision of the neutrino direction. The SPATS speed of sound analysis for pressure and shear waves is presented.Comment: To appear in the proceedings of the Acoustic and Radio EeV Neutrino detection Activities (ARENA) 2008 conferenc

Nucleotide sequence of the ARGRII regulatory gene and amino acid sequence homologies between ARGRII PPRI and GAL4 regulatory proteins.

We report here the DNA sequence of the ARGRII gene, one of the three regulatory genes involved in controlling the anabolism and catabolism of arginine in yeast. This gene encodes a protein of 880 amino acids with a deduced molecular mass of about 100 kDa. The ARGRII protein shows significant homology with two other regulatory proteins of yeast, PPRI and GAL4.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Characterization of two new genes essential for vegetative growth in Saccharomyces cerevisiae: nucleotide sequence determination and chromosome mapping.

Based on nucleotide sequence determination, we have identified two new yeast genes FUN80 and FUN81 located on chromosome XIII. They are both essential for cellular growth but their function is still unknown. FUN80 is closely linked to the ARGRI (or ARG80) gene while FUN81 is located next to the ARGRII (or ARG81) gene. Interestingly, the proteins encoded by these two genes have a long stretch of acidic amino acids within their C-terminal portions.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Limiting envelopes of a limestone under true triaxial stress state

info:eu-repo/semantics/publishe

Limits on the high-energy gamma and neutrino fluxes from the SGR 1806-20 giant flare of 27 December 2004 with the AMANDA-II detector

On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m(-2) s(-1) for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m(-2) s(-1) for gamma=-1.47 (-2) in the high-energy neutrino flux

Status of the SOUTH POLE ACOUSTIC TEST SETUP

Due to the low flux of ultrahigh energetic neutrinos induced in interactions of cosmic rays with the cosmic microwave background, very large instrumented volumes and new registration techniques are necessary for their detection. The south polar ice offers the unique opportunity to implement existing Cherenkov techniques as well as registration of radio and acoustic waves from the neutrino interaction. A simulation of a similar to 120km(3) hybrid optical/radio/acoustic detector showed that event rates of similar to 10 per year can be achieved. In this simulation the ultrasonic parameters of antarctic ice regarding absorption, scattering and environmental noise pose the key uncertainty. To evaluate the acoustic properties in-situ, the SOUTH POLE ACOUSTIC TEST SETUP (SPATS) has been created. An array of custom-made ultrasonic sensors and transmitters will be deployed on three strings in the upper 400 m of the holes of the ICECUBE experiment. The status of the experiment and a first evaluation of its performance axe presented here

The South Pole Acoustic Test Setup: Calibrations and lake test

In order to detect the small neutrino fluxes expected at ultra-high energies, large volumes of materials have to be instrumented with inexpensive but sensitive acoustic sensors. The South Pole Acoustic Test Setup (SPATS) will be installed in the Antarctic ice during the polar season 2006/2007 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 accomplished in Lake Tornetrisk, Abisko (Sweden). This allowed verification of the DAQ system, transmitter range and sensor performance. Here the results of the calibrations and the Abisko lake measurements are reported