As the energy of an incident neutrino cannot be accessed experimentally, muon neutrino energy spectra have to be inferred from energy-dependent observables, using deconvolution algorithms. This paper ...discusses the challenges associated with the application of deconvolution algorithms and presents two examples of spectral measurements obtained using the IceCube neutrino telescope in the 59- and 79-string configuration.
With very high energy (VHE) gamma-ray astronomy becoming a mature branch of observational astrophysics, and the multi-messenger sky being opened up by neutrino observatories and gravitational wave ...detectors, we here propose to set up a ring of imaging air Cherenkov telescopes – the Cherenkov Telescope Ring (CTR). The aim of this proposed project would be to facilitate continuous monitoring of sources on the VHE- and multi-messenger sky with minimal time delays and with high sensitivity. Development time and construction cost could be kept comparatively low by both including existing facilities into the monitoring effort, and by relying on substantial previous expertise gained in the community on the road towards the Cherenkov Telescope Array (CTA). This way, the Ring could prove to be a highly efficient facility greatly enhancing the science prospects for future ground-based high-energy astrophysics.
Spectra in astroparticle physics are commonly approximated by simple power laws. The steeply falling nature of these power laws, however, makes the detection of additional components rather ...challenging. This holds true especially, if the additional components are small compared to the established ones. Energy spectra of muon neutrinos are an interesting example of such a scenario, where the conventional and astrophysical components to the spectra have been established by the use of different analysis methods, such as likelihood fits or spectral deconvolution. The prompt component, although expected from theoretical models, has not yet been experimentally observed. Furthermore, the extraction of physics parameters is challenged by the large systematic uncertainties, especially at high energies. This contribution presents a different approach to the analysis of power-law spectra, which is based on functional data analysis. The method itself and its implications are discussed using muon and neutrino energy spectra as an example.
Relic neutrinos from the early universe are predicted to have a relatively
large number density, but extremely low energies. Hence, the only possible
interaction proceeds via neutrino capture on ...beta-decaying nuclei. In case
relic neutrinos are captured by beta-decaying nuclei in the Sun, the neutrinos
normally emerging from the decay of these nuclei will be missing from the
overall number of solar neutrinos registered in neutrino experiments. Within
the Sun, ^8\mathrm{B}$ and three nuclei from the CNO cycle are found to be
suitable for this kind of process. Their cross section as well as the possible
impact on the observed number of solar neutrinos are discussed. Assuming
standard neutrino oscillations, no deviations of neutrino flux measurements
from the predictions of the solar standard model are observed and upper limits
are derived accordingly.
The IceCube Neutrino Observatory measures high energy atmospheric neutrinos with high statistics. These atmospheric neutrinos are produced in cosmic ray interactions in the atmosphere, mainly by the ...decay of pions and kaons. The rate of the measured neutrinos is affected by seasonal temperature variations in the stratosphere, which are expected to increase with the energy of the particle. In this contribution, seasonal energy spectra are obtained using a novel spectrum unfolding approach, the Dortmund Spectrum Estimation Algorithm (DSEA+), in which the energy distribution from 125 GeV to 10 TeV is estimated from measured quantities with machine learning algorithms. The seasonal spectral difference to the annual average flux will be discussed based on preliminary results from IceCube's atmospheric muon neutrino data.
The IceCube Neutrino Observatory is a detector array at the South Pole with the central aim of studying astrophysical neutrinos. However, the majority of the detected neutrinos originates from cosmic ...ray interactions in the atmosphere. The rate of these atmospheric neutrinos shows a seasonal variation indicating that the rate changes with the temperature in the stratosphere. These seasonal changes of the atmospheric neutrino energy spectrum will be investigated using the Dortmund Spectrum Estimation Algorithm (DSEA). Based on results obtained from 10% of IceCube's atmospheric muon neutrino data, taken between 2011 and 2018, the differences of the measured fluxes during the Austral summer and winter will be discussed.
Obtaining the distribution of a physical quantity is a frequent objective in experimental physics. In cases where the distribution of the relevant quantity cannot be accessed experimentally, it has ...to be reconstructed from distributions of correlated quantities that are measured, instead. This reconstruction is called deconvolution. Cherenkov astronomy is a deconvolution use case which studies the energy distribution of cosmic gamma radiation to reason about the characteristics of celestial objects emitting such radiation. We present a novel unified view on deconvolution methods, rephrasing them in the language of data science. Based on our unified formulation, we propose a novel stopping condition that guarantees fast convergence. We compare existing and new methods on synthetic and real-world data, showing that our method converges faster and more accurately than the existing machine learning based approach.
Relic neutrinos from the early universe are predicted to have a relatively large number density, but extremely low energies. Hence, the only possible interaction proceeds via neutrino capture on ...beta-decaying nuclei. In case relic neutrinos are captured by beta-decaying nuclei in the Sun, the neutrinos normally emerging from the decay of these nuclei will be missing from the overall number of solar neutrinos registered in neutrino experiments. Within the Sun, \({}^8\mathrm{B}\) and three nuclei from the CNO cycle are found to be suitable for this kind of process. Their cross section as well as the possible impact on the observed number of solar neutrinos are discussed. Assuming standard neutrino oscillations, no deviations of neutrino flux measurements from the predictions of the solar standard model are observed and upper limits are derived accordingly.
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