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 Abhijit Samanta Physics , 2009, DOI: 10.1103/PhysRevD.81.037302 Abstract: We have studied the mass hierarchy with atmospheric neutrinos considering the muon energy and zenith angle of the event at the magnetized iron calorimeter detector. For $\chi^2$ analysis we have migrated the number of events from neutrino energy and zenith angle bins to muon energy and zenith angle bins using the two-dimensional energy-angle correlated resolution functions. The binning of data is made in two-dimensional grids of $\log_{10} E - L^{0.4}$ plane to get a better reflection of the oscillation pattern in the $\chi^2$ analysis. Then the $\chi^2$ is marginalized considering all possible systematic uncertainties of the atmospheric neutrino flux and cross section. The effects of the ranges of oscillation parameters on the marginalization are also studied. The lower limit of the range of $\theta_{13}$ for marginalization is found to be very crucial in determining the sensitivity of hierarchy for a given $\theta_{13}$. Finally, we show that one can discriminate atmospheric neutrino mass hierarchy at $>$90% C.L. if the lower limit of $\theta_{13} \ge 5^\circ$.
 Physics , 2014, Abstract: This Letter of Intent (LoI) describes the outline and plan for the Neutrino Telescope Array (NTA) project. High-energy neutrinos provide unique and indisputable evidence for hadronic acceleration. Recently, IceCube has reported astronomical neutrino candidates in excess of expectation from atmospheric secondaries, but is limited by the water Cherenkov detection method. A next generation high-energy neutrino telescope should be capable of establishing indisputable evidence for cosmic high-energy neutrinos. It should not only have orders-of-magnitude larger sensitivity, but also enough pointing accuracy to probe known or unknown astronomical objects, without suffering from atmospheric secondaries. The proposed installation is a large array of compound eye stations of imaging atmospheric Cherenkov and fluorescence detectors, with wide field of view and refined observational ability of air showers from cosmic tau neutrinos in the PeV-EeV energy range. This advanced optical complex system is based substantially on the development of All-sky Survey High Resolution Air-shower detector (Ashra) and applies the tau shower Earth-skimming method to survey PeV-EeV tau neutrinos. It allows wide (30 deg x 360 deg) and deep (~400 Mpc) survey observation for PeV-EeV tau neutrinos assuming the standard GRB neutrino fluence.In addition, it enjoys the pointing accuracy of better than 0.2 deg in essentially background-free conditions. With the advanced imaging of Earth-skimming tau showers in the wide field of view, we aim for clear discovery and identification of astronomical tau neutrino sources, providing inescapable evidence of the astrophysical hadronic model for acceleration and/or propagation of extremely high energy protons in the precisely determined direction.
 Physics , 1994, DOI: 10.1016/0370-1573(95)00003-Y Abstract: The topic of this review is the particle astrophysics of high energy neutrinos. High energy is defined as $E_{\nu} > 100$~MeV. Main topics include: -- atmospheric neutrinos and muons from $\pi$, $K$ and charm decay. They probe uncharted territory in neutrino oscillations and constitute both the background and calibration of high energy neutrino telescopes, -- sources of high energy neutrino beams: the galactic plane, the sun, X-ray binaries, supernova remnants and interactions of extra-galactic cosmic rays with background photons, -- an extensive review of the mechanisms by which active galaxies may produce high energy particle beams, -- high energy neutrino signatures of cold dark matter and, -- a brief review of detection techniques (water and ice Cherenkov detectors, surface detectors, radio- and acoustic detectors, horizontal airshower arrays) and the instruments under construction.
 Ioana Anghel Physics , 2013, Abstract: Many of the yet unanswered questions in neutrino physics, such as CP violation in the lepton sector or neutrino mass hierarchy, could be answered with higher sensitivity neutrino experiments. New photodetectors based on micro-channel plates are being developed by the Large-Area Picosecond Photo Detector (LAPPD) Collaboration. These photosensors have been shown to have excellent spatial and timing resolution. Using these devices in massive water Cherenkov detectors, we could significantly improve the vertex resolution for neutrinos enhancing background rejection for neutrino oscillation experiments. We present preliminary results on the reconstruction capabilities for single particles in water Cherenkov detectors using fast photosensors.
 Physics , 1995, DOI: 10.1016/0370-2693(95)01246-X Abstract: Due to their weak interactions, neutrinos can polarize a medium and acquire an induced charge. We consider the Cherenkov radiation emitted by neutrinos due to their effective electromagnetic interactions as they pass through a polarizable medium. The effect exists even for massless, chiral neutrinos, where no physics beyond the standard model needs to be assumed.
 Physics , 1999, Abstract: We discuss the Cherenkov process $\nu\to\nu\gamma$ in the presence of a homogeneous magnetic field. The neutrinos are taken to be massless with only standard-model couplings. The magnetic field fulfills the dual purpose of inducing an effective neutrino-photon vertex and of modifying the photon dispersion relation such that the Cherenkov condition $\omega<|{\bf k}|$ is fulfilled. For a field strength $B_{\rm crit}=m_e^2/e=4.41\times10^{13} Gauss$ and for $E=2m_e$ the Cherenkov rate is about $6\times10^{-11}s^{-1}$.
 Physics , 2015, Abstract: Bolometric detectors are excellent devices for the investigation of neutrinoless double-beta decay (0$\nu\beta\beta$). The observation of such decay would demonstrate the violation of lepton number, and at the same time it would necessarily imply that neutrinos have a Majorana character. The sensitivity of cryogenic detectors based on TeO$_2$ is strongly limited by the alpha background in the region of interest for the 0$\nu\beta\beta$ of $^{130}$Te. It has been demonstrated that particle discrimination in TeO$_2$ bolometers is possible measuring the Cherenkov light produced by particle interactions. However an event-by-event discrimination with NTD-based light detectors has to be demonstrated. We will discuss the performance of a highly-sensitive light detector exploiting the Neganov-Luke effect for signal amplification. The detector, being operated with NTD-thermistor and coupled to a 750 g TeO$_2$ crystal, shows the ability for an event-by-event identification of electron/gamma and alpha particles. The extremely low detector baseline noise, RMS 19 eV, demonstrates the possibility to enhance the sensitivity of TeO$_2$-based 0$\nu\beta\beta$ experiment to an unprecedented level.
 Franz Muheim Physics , 2000, Abstract: The 64-channel Multianode Photo Multiplier has been evaluated as a possible choice for the photo detectors of the LHCb Ring Imaging Cherenkov detector.
 Frank Krennrich Physics , 1999, DOI: 10.1016/S0927-6505(99)00056-0 Abstract: High energy gamma-ray astronomy has been established during the last decade through the launch of the Compton Gamma Ray Observatory (CGRO) and the success of its ground-based counterpart, the imaging atmospheric Cherenkov technique. In the aftermath of their important and surprising scientific results a worldwide effort developing and designing new generation atmospheric Cherenkov detectors is underway. These novel instruments will have higher sensitivity at E > 250 GeV, but most importantly, will be able to close the unexplored energy gap between 20 GeV and 250 GeV. Several ground-based detectors are proposed or under construction. Aspects of the techniques used and sensitivity are discussed in this overview paper. The instruments cover largely complementary energy ranges and together are expected to explore the gamma-ray sky between 20 GeV and 100 TeV with unprecedented sensitivity.
 Physics , 2007, DOI: 10.1103/PhysRevD.77.032003 Abstract: The atmospheric neutrino background for proton decay to positron and neutral pion in ring imaging water Cherenkov detectors is studied with an artificial accelerator neutrino beam for the first time. In total, about 314,000 neutrino events corresponding to about 10 megaton-years of atmospheric neutrino interactions were collected by a 1,000 ton water Cherenkov detector (KT). The KT charged-current single neutral pion production data are well reproduced by simulation programs of neutrino and secondary hadronic interactions used in the Super-Kamiokande (SK) proton decay search. The obtained proton to positron and neutral pion background rate by the KT data for SK from the atmospheric neutrinos whose energies are below 3 GeV is about two per megaton-year. This result is also relevant to possible future, megaton-scale water Cherenkov detectors.
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