| 1. |
- Abbasi, R., et al.
(författare)
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Acceptance Tests of more than 10 000 Photomultiplier Tubes for the multi-PMT Digital Optical Modules of the IceCube Upgrade
- 2024
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 19:7
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Tidskriftsartikel (refereegranskat)abstract
- More than 10 000 photomultiplier tubes (PMTs) with a diameter of 80 mm will be installed in multi-PMT Digital Optical Modules (mDOMs) of the IceCube Upgrade. These have been tested and pre-calibrated at two sites. A throughput of more than 1000 PMTs per week with both sites was achieved with a modular design of the testing facilities and highly automated testing procedures. The testing facilities can easily be adapted to other PMTs, such that they can, e.g., be re-used for testing the PMTs for IceCube-Gen2. Single photoelectron response, high voltage dependence, time resolution, prepulse, late pulse, afterpulse probabilities, and dark rates were measured for each PMT. We describe the design of the testing facilities, the testing procedures, and the results of the acceptance tests.
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| 2. |
- Abbasi, R., et al.
(författare)
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Characterization of the astrophysical diffuse neutrino flux using starting track events in IceCube
- 2024
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 2470-0010 .- 2470-0029. ; 110:2
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Tidskriftsartikel (refereegranskat)abstract
- A measurement of the diffuse astrophysical neutrino spectrum is presented using IceCube data collected from 2011-2022 (10.3 years). We developed novel detection techniques to search for events with a contained vertex and exiting track induced by muon neutrinos undergoing a charged-current interaction. Searching for these starting track events allows us to not only more effectively reject atmospheric muons but also atmospheric neutrino backgrounds in the southern sky, opening a new window to the sub-100 TeV astrophysical neutrino sky. The event selection is constructed using a dynamic starting track veto and machine learning algorithms. We use this data to measure the astrophysical diffuse flux as a single power law flux (SPL) with a best-fit spectral index of γ=2.58-0.09+0.10 and per-flavor normalization of φper-flavorAstro=1.68-0.22+0.19×10-18×GeV-1 cm-2 s-1 sr-1 (at 100 TeV). The sensitive energy range for this dataset is 3-550 TeV under the SPL assumption. This data was also used to measure the flux under a broken power law, however we did not find any evidence of a low energy cutoff.
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| 3. |
- Abbasi, R., et al.
(författare)
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Improved modeling of in-ice particle showers for IceCube event reconstruction
- 2024
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 19:6
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Tidskriftsartikel (refereegranskat)abstract
- The IceCube Neutrino Observatory relies on an array of photomultiplier tubes to detect Cherenkov light produced by charged particles in the South Pole ice. IceCube data analyses depend on an in-depth characterization of the glacial ice, and on novel approaches in event reconstruction that utilize fast approximations of photoelectron yields. Here, a more accurate model is derived for event reconstruction that better captures our current knowledge of ice optical properties. When evaluated on a Monte Carlo simulation set, the median angular resolution for in-ice particle showers improves by over a factor of three compared to a reconstruction based on a simplified model of the ice. The most substantial improvement is obtained when including effects of birefringence due to the polycrystalline structure of the ice. When evaluated on data classified as particle showers in the high-energy starting events sample, a significantly improved description of the events is observed.
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| 4. |
- Antel, C., et al.
(författare)
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Feebly-interacting particles : FIPs 2022 Workshop Report
- 2023
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Ingår i: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 83:12
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Forskningsöversikt (refereegranskat)abstract
- Particle physics today faces the challenge of explaining the mystery of dark matter, the origin of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent fine-tuning of the electro-weak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves new physics at mass scales comparable to familiar matter, below the GeV-scale, or even radically below, down to sub-eV scales, and with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and indeed, existing data provide numerous hints for such possibility. A vibrant experimental program to discover such physics is under way, guided by a systematic theoretical approach firmly grounded on the underlying principles of the Standard Model. This document represents the report of the FIPs 2022 workshop, held at CERN between the 17 and 21 October 2022 and aims to give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs.
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| 5. |
- Abdullahi, Asli M., et al.
(författare)
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The present and future status of heavy neutral leptons
- 2023
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Ingår i: Journal of Physics G. - : Institute of Physics Publishing (IOPP). - 0954-3899 .- 1361-6471. ; 50:2
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Tidskriftsartikel (refereegranskat)abstract
- The existence of nonzero neutrino masses points to the likely existence of multiple Standard Model neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, they are referred to as heavy neutral leptons (HNLs). In this white paper, we discuss the present experimental status of HNLs including colliders, beta decay, accelerators, as well as astrophysical and cosmological impacts. We discuss the importance of continuing to search for HNLs, and its potential impact on our understanding of key fundamental questions, and additionally we outline the future prospects for next-generation future experiments or upcoming accelerator run scenarios.
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| 6. |
- Goudzovski, Evgueni, et al.
(författare)
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New physics searches at kaon and hyperon factories
- 2023
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Ingår i: Reports on progress in physics (Print). - : Institute of Physics (IOP). - 0034-4885 .- 1361-6633. ; 86:1
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Forskningsöversikt (refereegranskat)abstract
- Rare meson decays are among the most sensitive probes of both heavy and light new physics. Among them, new physics searches using kaons benefit from their small total decay widths and the availability of very large datasets. On the other hand, useful complementary information is provided by hyperon decay measurements. We summarize the relevant phenomenological models and the status of the searches in a comprehensive list of kaon and hyperon decay channels. We identify new search strategies for under-explored signatures, and demonstrate that the improved sensitivities from current and next-generation experiments could lead to a qualitative leap in the exploration of light dark sectors.
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| 7. |
- Hostert, C, et al.
(författare)
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Ab-initio molecular dynamics model for density, elastic properties and short range order of Co-Fe-Ta-B metallic glass thin films
- 2011
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 23:47, s. 475401-
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Tidskriftsartikel (refereegranskat)abstract
- Density, elastic modulus and the pair distribution function of Co-Fe-Ta-B metallic glasses were obtained by ab-initio molecular dynamics simulations and measured for sputtered thin films using X-ray reflectivity, nanoindentation and X-ray diffraction using high energy photons. The computationally obtained density of 8.19 g/cm3 for Co43Fe20Ta5.5B31.5 and 8.42 g/cm3 for Co45.5Fe24Ta6B24.5, as well as the Young’s moduli of 273 and 251 GPa, respectively, are consistent with our experiments and literature data. These data, together with the good agreement between the theoretical and the experimental pair distribution functions, indicate that the here established model is useful to describe density, elasticity and short range order of Co-Fe-Ta-B metallic glass thin films. Irrespective of the investigated variation in chemical composition, (Co,Fe)-B cluster formation and Co-Fe interactions are identified by density of states analysis. Strong bonds within the structural units and between the metallic species may give rise to the comparatively large stiffness.
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| 8. |
- Hostert, Carolin, et al.
(författare)
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Density, elastic and magnetic properties of Co–Fe–Ta–Si metallic glasses by theory and experiment
- 2012
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Ingår i: Scripta Materialia. - : Elsevier. - 1359-6462 .- 1872-8456.
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio molecular dynamics simulations were employed to study the density, elastic and magnetic properties of Co–Fe–Ta–Si10 metallic glass thin films. A density of 8.03 g cm3, a Young’s modulus of 187 GPa and a volume magnetization of 0.089 lBA ˚ 3 werecalculated and validated by thin film experiments. The extensive stiffness of this glass may be related to the existence of strong(Fe,Co)–Si clusters as revealed by ab initio chemical short-range order data.
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| 9. |
- Yao, J. H., et al.
(författare)
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Synthesis and mechanical properties of Fe-Nb-B thin-film metallic glasses
- 2012
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 67:2, s. 181-184
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Tidskriftsartikel (refereegranskat)abstract
- Fe-Nb-B. thin-film metallic glasses (TFMGs) were synthesized via a combinatorial sputtering approach to probe the property-composition correlation. The boron content was found to dominate the mechanical properties of the TFMGs. The similar to 10% smaller strength of Fe-Nb-B TFMGs compared to existing bulk metallic glass with similar composition may be attributed to the absence of a network-like structure based on (Fe,M)(23)B-6 phase due to the extreme quenching conditions employed.
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