Search results for "oscillation"
showing 10 items of 1257 documents
Determining the neutrino mass with cyclotron radiation emission spectroscopy—Project 8
2017
The most sensitive direct method to establish the absolute neutrino mass is observation of the endpoint of the tritium beta-decay spectrum. Cyclotron Radiation Emission Spectroscopy (CRES) is a precision spectrographic technique that can probe much of the unexplored neutrino mass range with $\mathcal{O}({\rm eV})$ resolution. A lower bound of $m(\nu_e) \gtrsim 9(0.1)\, {\rm meV}$ is set by observations of neutrino oscillations, while the KATRIN Experiment - the current-generation tritium beta-decay experiment that is based on Magnetic Adiabatic Collimation with an Electrostatic (MAC-E) filter - will achieve a sensitivity of $m(\nu_e) \lesssim 0.2\,{\rm eV}$. The CRES technique aims to avoid…
Detecting the Diffuse Supernova Neutrino Background with LENA
2014
Low energy neutrino astronomy (LENA) has been proposed as a next generation 50 kt liquid scintillator detector. Its large target mass allows us to search for the diffuse supernova neutrino background (DSNB), which was generated by the cumulative emissions of all core-collapse supernovae throughout the Universe. Indistinguishable background from reactor and atmospheric electron antineutrinos limits the detection window to the energy range between 9.5 MeV and 25 MeV. Depending on the mean supernova neutrino energy, about 5 to 10 events per year are expected in this energy window. The background from neutral current reactions of atmospheric neutrinos surpasses the DSNB by more than one order m…
New constraints on coupled dark energy from the Planck satellite experiment
2013
We present new constraints on coupled dark energy from the recent measurements of the cosmic microwave background anisotropies from the Planck satellite mission. We found that a coupled dark energy model is fully compatible with the Planck measurements, deriving a weak bound on the dark matter-dark energy coupling parameter xi = -0.49(-0.31)(+0.19) at 68% C.L. Moreover if Planck data are fitted to a coupled dark energy scenario, the constraint on the Hubble constant is relaxed to H-0 = 72.1(-2.3)(+3.2) km/s/Mpc, solving the tension with the Hubble Space Telescope (HST) value. We show that a combined PLANCK + HST analysis provides significant evidence for coupled dark energy finding a nonzer…
Quantum decoherence and neutrino data
2006
In this work we perform global fits of microscopic decoherence models of neutrinos to all available current data, including LSND and KamLAND spectral distortion results. In previous works on related issues the models used were supposed to explain LSND results by means of quantum gravity induced decoherence. However those models were purely phenomenological without any underlying microscopic basis. It is one of the main purposes of this article to use detailed microscopic decoherence models with complete positivity, to fit the data.The decoherence in these models has contributions not only from stochastic quantum gravity vacua operating as a medium, but also from conventional uncertainties i…
Recent Developments in Neutrino/Antineutrino-Nucleus Interactions
2012
Recent experimental results and developments in the theoretical treatment of neutrino-nucleus interactions in the energy range of 1–10 GeV are discussed. Difficulties in extracting neutrino-nucleon cross sections from neutrino-nucleus scattering data are explained and significance of understanding nuclear effects for neutrino oscillation experiments is stressed. Detailed discussions of the status of two-body current contribution in the kinematic region dominated by quasielastic scattering and specific features of partonic nuclear effects in weak DIS scattering are presented.
BeppoSAX observation of the transient X-ray pulsar GS 1843+009
1999
Abstract The transient X-ray pulsar GS 1843+009 was observed by BeppoSAX satellite on 1997 April 4, while it was at flux level of 50 mCrab in the 20–200 keV energy band. Using the MECS and LECS concentrators, the source position was measured with unprecedented accuracy of 30. In this poster we present results on both spectral and temporal analysis.
Medium effects for terrestrial and atmospheric neutrino oscillations
2001
Matter effects in neutrino propagation translate into effective parameters for the oscillation and fake CP- and CPT-odd quantities, even in a scenario, such as $\Delta_{12}=0$, where no genuine CP violation is present. This fact seems to impose severe restrictions on the determination of intrinsic parameters of the system from long-baseline experiments. We show, however, that the resonance in the effective mixing $\tilde{\theta}_{13}$ can be observed for a certain range of baselines. This provides a way to measure the vacuum mixing angle $\theta_{13}$ and the sign of $\Delta m_{23}^2$ from atmospheric neutrinos, using a detector with energy resolution and charge discrimination.
The INTEGRAL experiment
1998
The International Gamma-ray Astrophysics Laboratory (INTEGRAL) is conceived as the next logical step in gamma-ray astronomy after the US Compton Gamma-Ray Observatory (CGRO) and the French/Russian SIGMA mission. The INTEGRAL scientific payload consists of two main instruments (Imager and Spectrometer) and two monitor instruments (X-Ray Monitor and Optical Transient Camera). The INTEGRAL spectrometer "SPI" is optimized for detailed measurements of gamma-ray lines and mapping of diffuse sources. It combines a coded aperture mask with an array of large volume, high-purity germanium detectors. The detectors make precise measurements of the gamma-ray energies over the 20 keV-8 MeV energy range. …
Performance of long modules of silicon microstrip detectors
1998
This note describes the performance of modules assembled with up to twelve silicon microstrip detectors. These modules were built for the instrumented Silicon Target (STAR) that has been installed in the NOMAD spectrometer. Laboratory and test beam results are compared with model predictions. For a module of nine detectors, test beam results indicate a signal--to--noise ratio of 19, a hit finding efficiency of 99.8\% and a spatial resolution of 6.0 $\mu$m. Laboratory measurements indicate that modules of twelve detectors exhibit a signal--to--noise ratio of the order of 16.
Oscillations of Dirac and Majorana neutrinos in matter and a magnetic field
2008
We study the evolution of massive mixed Dirac and Majorana neutrinos in matter under the influence of a transversal magnetic field. The analysis is based on relativistic quantum mechanics. We solve exactly the evolution equation for relativistic neutrinos, find the neutrino wave functions, and calculate the transition probability for spin-flavor oscillations. We analyze the dependence of the transition probability on the external fields and compare the cases of Dirac and Majorana neutrinos. The evolution of Majorana particles in vacuum is also studied and correction terms to the standard oscillation formula are derived and discussed. As a possible application of our results we discuss the s…