K. Helbing
A5068223009- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Particle physics theoretical and experimental studies
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Particle accelerators and beam dynamics
- Radio Wave Propagation Studies
- Nuclear Physics and Applications
- Nuclear physics research studies
- Ionosphere and magnetosphere dynamics
- Quantum Chromodynamics and Particle Interactions
- Radiation Detection and Scintillator Technologies
- Scientific Research and Discoveries
- Cryospheric studies and observations
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
- Gyrotron and Vacuum Electronics Research
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Atomic and Subatomic Physics Research
- X-ray Spectroscopy and Fluorescence Analysis
- Precipitation Measurement and Analysis
University of Wuppertal
2016-2025
The University of Texas at Arlington
2018-2024
Lawrence Berkeley National Laboratory
2004-2024
Southern University and Agricultural and Mechanical College
2013-2024
Clark Atlanta University
2006-2024
University of Alaska Anchorage
2007-2024
Providence College
2006-2024
UCLouvain
2023
TU Dortmund University
2023
Tufts University
2023
We have remotely mapped optical scattering and absorption in glacial ice at the South Pole for wavelengths between 313 560 nm depths 1100 2350 m. used pulsed continuous light sources embedded with AMANDA neutrino telescope, an array of more than six hundred photomultiplier tubes buried deep ice. At greater 1300 m, both coefficient absorptivity follow vertical variations concentration dust impurities, which are seen cores from other Antarctic sites track climatological changes. The varies by...
We report on the neutrino mass measurement result from first four-week science run of Karlsruhe Tritium Neutrino experiment KATRIN in spring 2019. Beta-decay electrons a high-purity gaseous molecular tritium source are energy analyzed by high-resolution MAC-E filter. A fit integrated electron spectrum over narrow interval around kinematic endpoint at 18.57 keV gives an effective square value $(-1.0^{+0.9}_{-1.1})$ eV$^2$. From this we derive upper limit 1.1 eV (90$\%$ confidence level)...
Abstract Since the discovery of neutrino oscillations, we know that neutrinos have non-zero mass. However, absolute neutrino-mass scale remains unknown. Here report upper limits on effective electron anti-neutrino mass, m ν , from second physics run Karlsruhe Tritium Neutrino experiment. In this experiment, is probed via a high-precision measurement tritium β -decay spectrum close to its endpoint. This method independent any cosmological model and does not rely assumptions whether Dirac or...
That neutrinos carry a nonvanishing rest mass is evidence of physics beyond the Standard Model elementary particles. Their absolute holds relevance in fields from particle to cosmology. We report on search for effective electron antineutrino with KATRIN experiment. performs precision spectroscopy tritium β-decay close kinematic endpoint. On basis first five measurement campaigns, we derived best-fit value <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow>...
A measurement of the atmospheric muon neutrino energy spectrum from 100 GeV to 400 TeV was performed using a data sample about 18 000 up-going events in IceCube. Boosted decision trees were used for event selection reject misreconstructed muons and obtain events. Background contamination final is less than 1%. This first neutrinos up TeV, fundamental understanding impact this background on astrophysical observations with The measured consistent predictions...
A search for muon neutrinos from neutralino annihilations in the Sun has been performed with IceCube 22-string neutrino detector using data collected 104.3 days of live time 2007. No excess over expected atmospheric background observed. Upper limits have obtained on annihilation rate captured neutralinos and converted to weakly interacting massive particle (WIMP) proton cross sections WIMP masses range 250-5000 GeV. These results are most stringent date Sun.
We present the results of time-integrated searches for astrophysical neutrino sources in both northern and southern skies. Data were collected using partially completed IceCube detector 40-string configuration recorded between 2008 April 5 2009 May 20, totaling 375.5 days livetime. An unbinned maximum likelihood ratio method is used to search signals. The data sample contains 36,900 events: 14,121 from sky, mostly muons induced by atmospheric neutrinos, 22,779 high-energy muons. analysis...
We report the first observation of an anisotropy in arrival direction cosmic rays with energies multi TeV region Southern sky using data from IceCube detector. Between June 2007 and March 2008, partially-deployed detector was operated a configuration 1320 digital optical sensors distributed over 22 strings at depths between 1450 2450 meters inside Antarctic ice. is neutrino detector, but are dominated by large background ray muons. Therefore, suitable for high-statistics studies sky. The...
IceCube has become the first neutrino telescope with a sensitivity below TeV flux predicted from gamma-ray bursts if are responsible for observed cosmic-ray above 10(18) eV. Two separate analyses using half-complete detector, one dedicated search neutrinos pγ interactions in prompt phase of burst fireball and other generic any emission these sources over wide range energies times, produced no evidence emission, excluding prevailing models at 90% confidence.
A direct measurement of the helicity dependence total photoabsorption cross section on proton was carried out at MAMI (Mainz) in energy range 200<Eγ<800MeV. The experiment used a 4π detection system, circularly polarized tagged photon beam, and frozen spin target. contributions to Gerasimov-Drell-Hearn sum rule forward polarizability γ0 determined from data are 226±5(stat)±12(syst)μb −187±8(stat)±10(syst)×10−6fm4, respectively, for 200<Eγ<800MeV.Received 13 March...
Self-annihilating or decaying dark matter in the Galactic halo might produce high energy neutrinos detectable with neutrino telescopes. We have conducted a search for such signal using 276 days of data from IceCube 22-string configuration detector acquired during 2007 and 2008. The effect model choice extracted limit is reduced by performing that considers outer region not Center. constrain any large scale anisotropy are able to set on self-annihilation cross section <\sigma_{A}v> \simeq...
A search for TeV-PeV muon neutrinos from unresolved sources was performed on AMANDA-II data collected between 2000 and 2003 with an equivalent live time of 807 days. This diffuse analysis sought to find extraterrestrial neutrino flux nonthermal components. The signal is expected have a harder spectrum than the atmospheric backgrounds. Since no excess events seen in over background, upper limit...
A search for sidereal modulation in the flux of atmospheric muon neutrinos IceCube was performed. Such a signal could be an indication Lorentz-violating physics. Neutrino oscillation models, derivable from extensions to standard model, allow neutrino oscillations that depend on neutrino's direction propagation. No such direction-dependent variation found. discrete Fourier transform method used constrain Lorentz and $CPT$-violating coefficients one these models. Because unique high energy...
We present the results of searches for high-energy muon neutrinos from 41 gamma-ray bursts (GRBs) in northern sky with IceCube detector its 22-string configuration active 2007/2008. The cover both prompt and a possible precursor emission as well model-independent, wide time window -1 h to +3 around each GRB. In contrast previous large GRB population, we do not utilize standard Waxman-Bahcall flux but calculate individual neutrino spectra all GRBs burst parameters measured by satellites. none...
We report on a search for extremely-high energy neutrinos with energies greater than 106 GeV using the data taken IceCube detector at South Pole. The was collected between April 2008 and May 2009 half-completed array. absence of signal candidate events in sample 333.5 days live time significantly improves model-independent limits from previous searches allows to place limit diffuse flux cosmic an E−2 spectrum range 2.0×106−6.3×109 level E2ϕ≤3.6×10−8 cm−2 sec−1 sr−1.Received 22 March...
The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is complex experiment with many components. More than 15 years ago, we published technical design report (TDR) [https://publikationen.bibliothek.kit.edu/270060419] describe hardware requirements achieve our sensitivity goal 0.2 eV at 90% C.L. on mass. Since then there has been considerable progress, culminating in publication first results...
We report on the data set, handling, and detailed analysis techniques of first neutrino-mass measurement by Karlsruhe Tritium Neutrino (KATRIN) experiment, which probes absolute scale via $\beta$-decay kinematics molecular tritium. The source is highly pure, cryogenic T$_2$ gas. $\beta$ electrons are guided along magnetic field lines toward a high-resolution, integrating spectrometer for energy analysis. A silicon detector counts above threshold spectrometer, so that scan thresholds produces...
We present the results of light sterile neutrino search from second KATRIN measurement campaign in 2019. Approaching nominal activity, $3.76 \times 10^6$ tritium $\beta$-electrons are analyzed an energy window extending down to $40\,$eV below endpoint at $E_0 = 18.57\,$keV. consider $3\nu+1$ framework with three active and one flavor. The analysis is sensitive a fourth mass eigenstate $m_4^2\lesssim1600\,$eV$^2$ active-to-sterile mixing $|U_{e4}|^2 \gtrsim 6 10^{-3}$. As no sterile-neutrino...
We report on the direct search for cosmic relic neutrinos using data acquired during first two science campaigns of KATRIN experiment in 2019. Beta-decay electrons from a high-purity molecular tritium gas source are analyzed by high-resolution MAC-E filter around end point at 18.57 keV. The analysis is sensitive to local neutrino overdensity ratio η<9.7×10^{10}/α (1.1×10^{11}/α) 90% (95%) confidence level with α=1 (0.5) Majorana (Dirac) neutrinos. A fit integrated electron spectrum over...