4 research outputs found
Impact of the lower Jurassic Dunlin Group depositional elements on the Aurora CO<sub>2</sub> storage site, EL001, northern North Sea, Norway
No full textNorthern Lights is the CO2 transport and storage component of Longship, the Norwegian full-scale CCS project. Injection is planned into an under-explored sloping saline aquifer in the northern North Sea, the Johansen and Cook formations of the Lower Jurassic Dunlin Group. To bridge the information gap, well 31/5-7 (Eos) was drilled. The comprehensive dataset acquired was fundamental to interpret the depositional environment and determine the scale and spatial distribution of heterogeneities, as input to 3-D models aimed at improving storage resource assessment and understanding the injected CO2 plume behaviour over time. The interpreted gross depositional environments of the storage units are marginal- to shallow-marine, arranged in three successive fining-upwards intervals. The lower interval includes coastal deposits with mixed wave- and river influence, correlatable over a large distance, dominated by meso-scale heterogeneities. The middle interval records paralic deposits with a wave- and tidal- interplay generating higher vertical and lateral variability. The upper interval is interpreted as tidal-dominated, predominantly with cm-scale heterogeneities. The repeated fining-upwards trends are ideal for plume redistribution and efficient CO2 storage, and the reconstructed lateral depositional trends associated with generally good properties indicate a high storage potential. The Eos well data enabled building the properties distribution model, highlighting the importance of well control for storage evaluation.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Applied Geolog
Observation of Seven Astrophysical Tau Neutrino Candidates with IceCube
No full textWe report on a measurement of astrophysical tau neutrinos with 9.7 years of IceCube data. Using convolutional neural networks trained on images derived from simulated events, seven candidate events were found with visible energies ranging from roughly 20 TeV to 1 PeV and a median expected parent energy of about 200 TeV. Considering backgrounds from astrophysical and atmospheric neutrinos, and muons from decays in atmospheric air showers, we obtain a total estimated background of about 0.5 events, dominated by non- astrophysical neutrinos. Thus, we rule out the absence of astrophysical at the level. The measured astrophysical flux is consistent with expectations based on previously published IceCube astrophysical neutrino flux measurements and neutrino oscillations.Accepted for publication in Physical Review Letters. This version includes full author list metadat
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Search for Neutrino Emission from Hard X-Ray AGN with IceCube
No full textActive galactic nuclei (AGN) are promising candidate sources of high-energy astrophysical neutrinos, since they provide environments rich in matter and photon targets where cosmic-ray interactions may lead to the production of gamma rays and neutrinos. We searched for high-energy neutrino emission from AGN using the Swift-BAT Spectroscopic Survey catalog of hard X-ray sources and 12 yr of IceCube muon track data. First, upon performing a stacked search, no significant emission was found. Second, we searched for neutrinos from a list of 43 candidate sources and found an excess from the direction of two sources, the Seyfert galaxies NGC 1068 and NGC 4151. We observed NGC 1068 at flux ϕνμ+ν¯μ = 4.02-+1.521.58 × 10-11 TeV−1 cm−2 s−1 normalized at 1 TeV, with a power-law spectral index γ = 3.10-+0.220.26, consistent with previous IceCube results. The observation of a neutrino excess from the direction of NGC 4151 is at a posttrial significance of 2.9σ. If interpreted as an astrophysical signal, the excess observed from NGC 4151 corresponds to a flux ϕνμ+ν¯μ = 1.51-+0.810.99 × 10-11 TeV−1 cm−2 s−1 normalized at 1 TeV and γ = 2.83-+0.280.3
GollumFit: An IceCube Open-Source Framework for Binned-Likelihood Neutrino Telescope Analyses
No full textWe present GollumFit, a framework designed for performing binned-likelihood analyses on neutrino telescope data. GollumFit incorporates model parameters common to any neutrino telescope and also model parameters specific to the IceCube Neutrino Observatory. We provide a high-level overview of its key features and how the code is organized. We then discuss the performance of the fitting in a typical analysis scenario, highlighting the ability to fit over tens of nuisance parameters. We present some examples showing how to use the package for likelihood minimization tasks. This framework uniquely incorporates the particular model parameters necessary for neutrino telescopes, and solves an associated likelihood problem in a time-efficient manner
