348 research outputs found
Design, characterization and installation of the NEXT-100 cathode and electroluminescence regions
NEXT-100 is currently being constructed at the Laboratorio Subterr\'aneo de
Canfranc in the Spanish Pyrenees and will search for neutrinoless double beta
decay using a high-pressure gaseous time projection chamber (TPC) with 100 kg
of xenon. Charge amplification is carried out via electroluminescence (EL)
which is the process of accelerating electrons in a high electric field region
causing secondary scintillation of the medium proportional to the initial
charge. The NEXT-100 EL and cathode regions are made from tensioned hexagonal
meshes of 1 m diameter. This paper describes the design, characterization, and
installation of these parts for NEXT-100. Simulations of the electric field are
performed to model the drift and amplification of ionization electrons produced
in the detector under various EL region alignments and rotations. Measurements
of the electrostatic breakdown voltage in air characterize performance under
high voltage conditions and identify breakdown points. The electrostatic
deflection of the mesh is quantified and fit to a first-principles mechanical
model. Measurements were performed with both a standalone test EL region and
with the NEXT-100 EL region before its installation in the detector. Finally,
we describe the parts as installed in NEXT-100, following their deployment in
Summer 2023.Comment: 35 pages, 25 Figures, update includes accepted version in JINS
Update on the Combined Analysis of Muon Measurements from Nine Air Shower Experiments
Over the last two decades, various experiments have measured muon densities in extensive air showers over several orders of magnitude in primary energy. While some experiments observed differences in the muon densities between simulated and experimentally measured air showers, others reported no discrepancies. We will present an update of the meta-analysis of muon measurements from nine air shower experiments, covering shower energies between a few PeV and tens of EeV and muon threshold energies from a few 100 MeV to about 10GeV. In order to compare measurements from different experiments, their energy scale was cross-calibrated and the experimental data has been compared using a universal reference scale based on air shower simulations. Above 10 PeV, we find a muon excess with respect to simulations for all hadronic interaction models, which is increasing with shower energy. For EPOS-LHC and QGSJet-II.04 the significance of the slope of the increase is analyzed in detail under different assumptions of the individual experimental uncertainties
Search for Spatial Correlations of Neutrinos with Ultra-high-energy Cosmic Rays
For several decades, the origin of ultra-high-energy cosmic rays (UHECRs) has been an unsolved question of high-energy astrophysics. One approach for solving this puzzle is to correlate UHECRs with high-energy neutrinos, since neutrinos are a direct probe of hadronic interactions of cosmic rays and are not deflected by magnetic fields. In this paper, we present three different approaches for correlating the arrival directions of neutrinos with the arrival directions of UHECRs. The neutrino data are provided by the IceCube Neutrino Observatory and ANTARES, while the UHECR data with energies above ∼50 EeV are provided by the Pierre Auger Observatory and the Telescope Array. All experiments provide increased statistics and improved reconstructions with respect to our previous results reported in 2015. The first analysis uses a high-statistics neutrino sample optimized for point-source searches to search for excesses of neutrino clustering in the vicinity of UHECR directions. The second analysis searches for an excess of UHECRs in the direction of the highest-energy neutrinos. The third analysis searches for an excess of pairs of UHECRs and highest-energy neutrinos on different angular scales. None of the analyses have found a significant excess, and previously reported overfluctuations are reduced in significance. Based on these results, we further constrain the neutrino flux spatially correlated with UHECRs
Measurement of atmospheric neutrino mixing with improved IceCube DeepCore calibration and data processing
We describe a new data sample of IceCube DeepCore and report on the latest measurement of atmospheric neutrino oscillations obtained with data recorded between 2011–2019. The sample includes significant improvements in data calibration, detector simulation, and data processing, and the analysis benefits from a sophisticated treatment of systematic uncertainties, with significantly greater level of detail since our last study. By measuring the relative fluxes of neutrino flavors as a function of their reconstructed energies and arrival directions we constrain the atmospheric neutrino mixing parameters to be sin2θ23=0.51±0.05 and Δm232=2.41±0.07×10−3 eV2, assuming a normal mass ordering. The errors include both statistical and systematic uncertainties. The resulting 40% reduction in the error of both parameters with respect to our previous result makes this the most precise measurement of oscillation parameters using atmospheric neutrinos. Our results are also compatible and complementary to those obtained using neutrino beams from accelerators, which are obtained at lower neutrino energies and are subject to different sources of uncertainties
Measurement of Atmospheric Neutrino Mixing with Improved IceCube DeepCore Calibration and Data Processing
We describe a new data sample of IceCube DeepCore and report on the latest
measurement of atmospheric neutrino oscillations obtained with data recorded
between 2011-2019. The sample includes significant improvements in data
calibration, detector simulation, and data processing, and the analysis
benefits from a detailed treatment of systematic uncertainties, with
significantly higher level of detail since our last study. By measuring the
relative fluxes of neutrino flavors as a function of their reconstructed
energies and arrival directions we constrain the atmospheric neutrino mixing
parameters to be and , assuming a normal mass ordering. The
resulting 40\% reduction in the error of both parameters with respect to our
previous result makes this the most precise measurement of oscillation
parameters using atmospheric neutrinos. Our results are also compatible and
complementary to those obtained using neutrino beams from accelerators, which
are obtained at lower neutrino energies and are subject to different sources of
uncertainties
A Search for Coincident Neutrino Emission from Fast Radio Bursts with Seven Years of IceCube Cascade Events
This paper presents the results of a search for neutrinos that are spatially
and temporally coincident with 22 unique, non-repeating Fast Radio Bursts
(FRBs) and one repeating FRB (FRB121102). FRBs are a rapidly growing class of
Galactic and extragalactic astrophysical objects that are considered a
potential source of high-energy neutrinos. The IceCube Neutrino Observatory's
previous FRB analyses have solely used track events. This search utilizes seven
years of IceCube's cascade events which are statistically independent of the
track events. This event selection allows probing of a longer range of extended
timescales due to the low background rate. No statistically significant
clustering of neutrinos was observed. Upper limits are set on the
time-integrated neutrino flux emitted by FRBs for a range of extended
time-windows
Searches for Neutrinos from LHAASO ultra-high-energy {\gamma}-ray sources using the IceCube Neutrino Observatory
Galactic PeVatrons are Galactic sources theorized to accelerate cosmic rays
up to PeV in energy. The accelerated cosmic rays are expected to interact
hadronically with nearby ambient gas or the interstellar medium, resulting in
{\gamma}-rays and neutrinos. Recently, the Large High Altitude Air Shower
Observatory (LHAASO) identified 12 {\gamma}-ray sources with emissions above
100 TeV, making them candidates for PeV cosmic-ray accelerators (PeVatrons).
While at these high energies the Klein-Nishina effect suppresses exponentially
leptonic emission from Galactic sources, evidence for neutrino emission would
unequivocally confirm hadronic acceleration. Here, we present the results of a
search for neutrinos from these {\gamma}-ray sources and stacking searches
testing for excess neutrino emission from all 12 sources as well as their
subcatalogs of supernova remnants and pulsar wind nebulae with 11 years of
track events from the IceCube Neutrino Observatory. No significant emissions
were found. Based on the resulting limits, we place constraints on the fraction
of {\gamma}-ray flux originating from the hadronic processes in the Crab Nebula
and LHAASOJ2226+6057
Limits on Neutrino Emission from GRB 221009A from MeV to PeV using the IceCube Neutrino Observatory
Gamma-ray bursts (GRBs) have long been considered a possible source of
high-energy neutrinos. While no correlations have yet been detected between
high-energy neutrinos and GRBs, the recent observation of GRB 221009A - the
brightest GRB observed by Fermi-GBM to date and the first one to be observed
above an energy of 10 TeV - provides a unique opportunity to test for hadronic
emission. In this paper, we leverage the wide energy range of the IceCube
Neutrino Observatory to search for neutrinos from GRB 221009A. We find no
significant deviation from background expectation across event samples ranging
from MeV to PeV energies, placing stringent upper limits on the neutrino
emission from this source.Comment: Version in ApJ Letters Focus on the Ultra-luminous Gamma-Ray Burst
GRB 221009
Multimessenger Gamma-Ray and Neutrino Coincidence Alerts using HAWC and IceCube sub-threshold Data
The High Altitude Water Cherenkov (HAWC) and IceCube observatories, through
the Astrophysical Multimessenger Observatory Network (AMON) framework, have
developed a multimessenger joint search for extragalactic astrophysical
sources. This analysis looks for sources that emit both cosmic neutrinos and
gamma rays that are produced in photo-hadronic or hadronic interactions. The
AMON system is running continuously, receiving sub-threshold data (i.e. data
that is not suited on its own to do astrophysical searches) from HAWC and
IceCube, and combining them in real-time. We present here the analysis
algorithm, as well as results from archival data collected between June 2015
and August 2018, with a total live-time of 3.0 years. During this period we
found two coincident events that have a false alarm rate (FAR) of
coincidence per year, consistent with the background expectations. The
real-time implementation of the analysis in the AMON system began on November
20th, 2019, and issues alerts to the community through the Gamma-ray
Coordinates Network with a FAR threshold of coincidences per year.Comment: 14 pages, 5 figures, 3 table
IceCat-1: The IceCube Event Catalog of Alert Tracks
We present a catalog of likely astrophysical neutrino track-like events from the IceCube Neutrino Observatory. IceCube began reporting likely astrophysical neutrinos in 2016, and this system was updated in 2019. The catalog presented here includes events that were reported in real time since 2019, as well as events identified in archival data samples starting from 2011. We report 275 neutrino events from two selection channels as the first entries in the catalog, the IceCube Event Catalog of Alert Tracks, which will see ongoing extensions with additional alerts. The Gold and Bronze alert channels respectively provide neutrino candidates with a 50% and 30% probability of being astrophysical, on average assuming an astrophysical neutrino power-law energy spectral index of 2.19. For each neutrino alert, we provide the reconstructed energy, direction, false-alarm rate, probability of being astrophysical in origin, and likelihood contours describing the spatial uncertainty in the alert\u27s reconstructed location. We also investigate a directional correlation of these neutrino events with gamma-ray and X-ray catalogs, including 4FGL, 3HWC, TeVCat, and Swift-BAT
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