Observation of High-Energy Astrophysical Neutrinos in Three Years of IceCube Data

A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV - PeV range at the level of $10^{-8}\, \mathrm{GeV}\, \mathrm{cm}^{-2}\, \mathrm{s}^{-1}\, \mathrm{sr}^{-1}$ per flavor and reject a purely atmospheric explanation for the combined 3-year data at $5.7 \sigma$. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year dataset, with a livetime of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000 TeV event is the highest-energy neutrino interaction ever observed.Comment: 8 pages, 5 figures. Accepted by PRL. The event catalog, event displays, and other data tables are included after the final page of the article. Changed from the initial submission to reflect referee comments, expanding the section on atmospheric backgrounds, and fixes offsets of up to 0.9 seconds in reported event times. Address correspondence to: J. Feintzeig, C. Kopper, N. Whitehor

Performance of the prototype Silicon Tracking System of the CBM experiment tested with heavy-ion beams at SIS18

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) is a heavy-ion experiment designed to study nuclear matter at the highest baryonic density. For high-statistics measurements of rare probes, collision rates of up to 10 MHz are targeted. The experiment, therefore, requires fast and radiation-hard detectors, self-triggered detector front-ends, free-streaming readout architecture, and online event reconstruction. The Silicon Tracking System (STS) is the main tracking detector of CBM, designed to reconstruct the trajectories of charged particles with efficiency larger than 95%, a relative momentum uncertainty better than 2% for particle momenta larger than 1 GeV/c inside a 1 Tm magnetic field, and to identify complex decay topologies. It comprises 876 double-sided silicon strip modules arranged in 8 tracking stations. A prototype of this detector, consisting of 12 modules arranged in three tracking stations, is installed in the mini-CBM demonstrator. This experimental setup is a small-scale precursor to the full CBM detector, composed of sub-units of all major CBM systems installed on the SIS18 beamline. In various beam campaigns taken between 2021 and 2024, heavy ion collisions at 1–2 AGeV with an average collision rate of 500 kHz have been recorded. This allows for the evaluation of the operational performance of the STS detector, including signal-to-noise ratio, charge distribution, time and position resolution, hit reconstruction efficiency, and its potential for track and vertex reconstruction

PINGU: a vision for neutrino and particle physics at the South Pole

The Precision IceCube Next Generation Upgrade (PINGU) is a proposed lowenergy in-fill extension to the IceCube Neutrino Observatory. With detection technology modeled closely on the successful IceCube example, PINGU will provide a 6 Mton effective mass for neutrino detection with an energy threshold of a few GeV. With an unprecedented sample of over 60 000 atmospheric neutrinos per year in this energy range, PINGU will make highly competitive measurements of neutrino oscillation parameters in an energy range over an order of magnitude higher than long-baseline neutrino beam experiments. PINGU will measure the mixing parameters Θ23 and Δm232, including the octant of Θ23 for a wide range of values, and determine the neutrino mass ordering at 3σ median significance within five years of operation. PINGU's high precision measurement of the rate of nt appearance will provide essential tests of the unitarity of the 3 ×3 PMNS neutrino mixing matrix. PINGU will also improve the sensitivity of searches for low mass dark matter in the Sun, use neutrino tomography to directly probe the composition of the Earth's core, and improve IceCube's sensitivity to neutrinos from Galactic supernovae. Reoptimization of the PINGU design has permitted substantial reduction in both cost and logistical requirements while delivering performance nearly identical to configurations previously studied

Sensitivity to cno cycle solar neutrinos in borexino

Parallel Contributed Talk at the 'XIX International Workshop on Neutrino Telescopes' on line - 18-26 February, 202

Measurement of pppp and CNO cycle solar neutrinos with Borexino

This work mainly deals with the study and measurement of solar neutrinos with the liquid scintillator detector Borexino, which is located at the Laboratori Nazionali del Gran Sasso (LNGS) in L'Aquila, Italy. Solar neutrinos are particles, which are created in the core of the Sun as a result of fusion reactions. This involves the proton-proton or $pp$ fusion as the main mechanism and the carbon-nitrogen-oxygen or CNO cycle as a secondary one. Both processes explain how energy is produced in the Sun or stars in general, i.e. how hydrogen is burned into helium. In the $pp$ fusion, two hydrogen nuclei or protons fuse together and initiate the so-called $pp$ chain. The CNO cycle on the other hand is initiated by the fusion of protons with carbon-12 isotopes. As a result of these reactions, solar neutrinos are produced, which need about eight minutes to reach the earth and thus represent a direct source of information to observe the solar interior. The energy and flux distribution, i.e. the number of emitted neutrinos per square centimeter and per second, of these neutrinos can be predicted precisely with the help of nuclear physics and the Standard Solar Model. This information can be used to determine the energy distribution of scattered electrons induced by solar neutrinos. These spectra can be used as a model to describe the data measured with the Borexino detector, keeping the scintillator background to a minimum and knowing its components precisely. This work is mainly concerned with the measurement of $pp$-, $pep$-, $^{7}\textrm{Be}$- and $^{8}\textrm{B}$-neutrinos from the $pp$ chain, and CNO neutrinos from the CNO cycle. \newline The second topic of this work is a study about the measurement of the shape factor of the $\beta^{-}$ radioactive source $^{144}\textrm{Pr}$ using a plastic scintillator setup located at the research center CEA in Paris-Saclay, France. The investigation of the $^{144}\textrm{Pr}$ source was developed for the SOX project (SOX = short distance neutrino oscillations with Borexino) and represented a sample source with lower activity. The main source, which was in production and ultimately could not be made available, was to be placed under the Borexino detector to study neutrino oscillations at short distances with respect to the existence of sterile neutrinos. However, the project was officially cancelled at the beginning of $2018$ as it was not possible to prepare the main source. As a consequence, the focus on this topic had to be significantly reduced within this work

Measurement of pp-chain Solar Neutrinos with Borexino

The Borexino detector, located at the Laboratori Nazionali del Gran Sasso in Italy, is a liquid scintillator detector with a primary goal to measure low-energy neutrinos created in the core of the Sun. In comparison to photons which need around hundred thousand years to reach the surface of the Sun, solar neutrinos are able to reach the earth around eight minutes after their creation. Thus, the solar neutrino measurement opens the window to understand the properties of the Sun, namely the fusion mechanisms (pp-chain and CNO cycle) or the metallicity problem, and generally to test the predictions of the standard solar model. Furthermore, it is possible to study neutrino oscillation parameters and search for non-standard interactions through the deviations from the Mikheyev-Smirnov-Wolfenstein-Large-Mixing-Angle scenario (MSW-LMA). To increase the sensitivity for pep and CNO neutrinos, the multivariate fit technique has been developed, which takes into account additional information of the radial and pulse shape distributions of events. The talk gives an introduction to the solar neutrino physics and discusses the recently published results for the pp, pep, 7Be and 8B neutrino rates as well as the perspective to measure the neutrinos from the CNO cycle. This talk is presented in the name of the Borexino Collaboration