An underwater acoustic sensor array spanning ~1500 km^3 is used to search for cosmic-ray neutrinos of ultra-high energies (UHE, E > 10^18 eV). Approximately 328 million triggers accumulated over an ...integrated 130 days of data taking are analysed. The sensitivity of the experiment is determined from a Monte Carlo simulation of the array using recorded noise conditions and expected waveforms. Two events are found to have properties compatible with showers in the energy range 10^24 to 5x10^24 eV and 10^22 to 5x10^22 eV. Since the understanding of impulsive backgrounds is limited, a flux upper limit is set providing the most sensitive limit on UHE neutrinos using the acoustic technique.
In 2014 the number of active cell phones worldwide for the first time surpassed the number of humans. Cell phone camera quality and onboard processing power (both CPU and GPU) continue to improve ...rapidly. In addition to their primary purpose of detecting photons, camera image sensors on cell phones and other ubiquitous devices such as tablets, laptops and digital cameras can detect ionizing radiation produced by cosmic rays and radioactive decays. While cosmic rays have long been understood and characterized as a nuisance in astronomical cameras, they can also be identified as a signal in idle camera image sensors. We present the Distributed Electronic Cosmic-ray Observatory (DECO), a platform for outreach and education as well as for citizen science. Consisting of an app and associated database and web site, DECO harnesses the power of distributed camera image sensors for cosmic-ray detection.
We have developed an application-specific integrated circui (ASIC) for photomultipler tube (PMT) waveform digitization which is well-suited for the Schwarzschild-Couder optical system under ...development for the Cherenkov Telescope Array (CTA) project. The key feature of the "TARGET" ASIC is the ability to read 16 channels in parallel at a sampling speed of 1 GSa/s or faster. In combination with a focal plane instrumented with 64-channel multi-anode PMTs (MAPMTs), TARGET digitizers will enable CTA to achieve a wider field of view than the current Cherenkov telescopes and significantly reduce the cost per channel of the camera and readout electronics. We have also developed a prototype camera module, consisting of 4 TARGET ASICs and a 64-channel MAPMT. We report results from performance testing of the camera module and of the TARGET ASIC itself.
The South Pole Acoustic Test Setup (SPATS) was built to evaluate the acoustic characteristics of the South Pole ice in the 10 kHz to 100 kHz frequency range, for the purpose of assessing the ...feasibility of an acoustic neutrino detection array at the South Pole. The SPATS hardware consists of four vertical strings deployed in the upper 500 m of the South Pole ice cap. The strings form a trapezoidal array with a maximum baseline of 543 m. Each string has 7 stages equipped with one transmitter and one sensor module. Sound is detected or generated by piezoelectric ceramic elements inside the modules. Analogue signals are sent to the surface on electric cables where they are digitized by a PC-based data acquisition system. The data from all strings are collected on a central computer in the IceCube Laboratory from where they are send to a central data storage facility via a satellite link or stored locally on tape. A technical overview of SPATS and its performance is presented.
Acoustic detection of ultra-high energy neutrinos Vandenbroucke, J.; Lehtinen, N.; Zhao, Y. ...
Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492),
2003, Letnik:
3
Conference Proceeding
Over the past two years, data have been collected at an array of hydrophones in a search for acoustic signatures of ultra-high energy neutrinos from space. The Study of Acoustic Ultra-high energy ...Neutrino Detection (SAUND) is a first step towards developing a novel detection method for one of the outstanding problems of both particle physics and astrophysics. The project has produced the first measurement of the ultra-high energy neutrino flux with an acoustic array. It has also provided important technical information that could be used to design a new array dedicated entirely to cosmic ray neutrino detection. In the past decade several groups have developed undersea arrays of instruments to detect subatomic particles from cosmic radiation. Most of these experiments use arrays of photo-multiplier tubes that detect light emitted by the particles as they traverse water at the speed of light. In July 2001, SAUND equipped seven hydrophones at this facility, the Atlantic Undersea Test and Evaluation Center (AUTEC) for neutrino detection. AUTEC features several arrays of bottom-mounted hydrophones spanning 250 km/sup 2/ in the Tongue of the Ocean (TOTO) in the Bahamas. The TOTO is a good environment for underwater acoustics: it is a deep-sea cul-de-sac, attaining depths of 1-2 km within several miles of shore; and it has very little boat traffic. At AUTEC we have been able to run the SAUND system in parasitic mode, turning it on whenever no AUTEC activities are scheduled. In practice this has allowed us to run the neutrino detector with 70% live time. Our detection strategy is to monitor all 7 hydrophones continuously and pass the pressure level of each through a digital filter matched to the theoretical neutrino waveform. The neutrino waveform is predicted to be a simple bi-polar pulse. Research conducted by SAUND will aid in the development of a large-scale acoustic neutrino detector, should one be built. Because the neutrino path is a line source, the acoustic radiation of neutrinos is confined to a disk 100 times wider than it is thick. We have determined a successful method of acoustic source localization for the specific situation of neutrino detection. This is necessary both for background rejection and for reconstructing the neutrino energy. We have studied the effects of sound-ray refraction, a difficult effect to account for and one that was not previously considered for neutrino detection. Finally, we have studied how to optimize array location relative to the sea floor and surface, interphone spacing, and geometric configuration.
Extracellular vesicles (EVs) can be functionalized to display specific protein receptors on their surface. However, surface-display technology typically labels only a small fraction of the EV ...population. Here, we show that the joint display of two different therapeutically relevant protein receptors on EVs can be optimized by systematically screening EV-loading protein moieties. We used cytokine-binding domains derived from tumour necrosis factor receptor 1 (TNFR1) and interleukin-6 signal transducer (IL-6ST), which can act as decoy receptors for the pro-inflammatory cytokines tumour necrosis factor alpha (TNF-α) and IL-6, respectively. We found that the genetic engineering of EV-producing cells to express oligomerized exosomal sorting domains and the N-terminal fragment of syntenin (a cytosolic adaptor of the single transmembrane domain protein syndecan) increased the display efficiency and inhibitory activity of TNFR1 and IL-6ST and facilitated their joint display on EVs. In mouse models of systemic inflammation, neuroinflammation and intestinal inflammation, EVs displaying the cytokine decoys ameliorated the disease phenotypes with higher efficacy as compared with clinically approved biopharmaceutical agents targeting the TNF-α and IL-6 pathways.
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