Our latest publications
A list of our 100 latest publications, taken from Cristin. The list is not complete.
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Zwalinski, L.; Zormpa, O.; Zorbas, T. G.; Zografos, A.; Zoch, K. & Zoccoli, A.
[Show all 2,915 contributors for this article]
(2026).
Electroweak diboson production in association with a high-mass dijet system in semileptonic final states from pp collisions at √s=13 TeV with the ATLAS detector.
European Physical Journal C.
ISSN 1434-6044.
86(4).
doi:
10.1140/epjc/s10052-025-15217-3.
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This paper reports the observation of electroweak diboson (WW/WZ/ZZ) production in association with a high-mass dijet system, in which final states with one boson decaying leptonically and the other boson decaying hadronically are studied. The hadronically decaying W/Z boson is reconstructed as either two small-radius jets or one large-radius
jet with jet substructure requirements. The data analyzed correspond to an integrated luminosity of 140 fb−1 of proton–proton collisions at a center-of-mass energy of
√s = 13 TeV collected with the ATLAS detector during the 2015-2018 data taking at the Large Hadron Collider. The electroweak production of WW/WZ/ZZ in association
with two jets is observed in a phase space dominated by vector-boson scattering with a significance of 7.4σ (expected 6.1σ) and the signal strength is determined to be 1.28+0.23
−0.21. The corresponding production cross section in a fiducial phase space is measured in addition. The signal strengths of both electroweak and QCD associated diboson productions are furthermore measured in a two-dimensional fit, the result of which agrees with the Standard Model prediction. The data are interpreted in the context of a dimension-8 effective field theory to probe anomalous quartic gauge couplings resulting in the first set of exclusion limits on the Wilson coefficients in the semileptonic channel reported by the ATLAS Collaboration. The observed limits for the S02, T0 and M0 operators are (−3.96 < fS02/4 < 3.96) TeV−4, (−0.25 < fT 0/4 < 0.22) TeV−4, (−1.26 < fM0/4 < 1.25) TeV−4.
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Zwalinski, L.; Zormpa, O.; Zorbas, T. G.; Zografos, A.; Zoch, K. & Zoccoli, A.
[Show all 2,928 contributors for this article]
(2026).
Measurement of the W-boson angular coefficients and transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector.
European Physical Journal C.
ISSN 1434-6044.
86(5).
doi:
10.1140/epjc/s10052-025-15264-w.
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The angular distributions of Drell–Yan lepton pairs provide sensitive probes of the underlying dynamics of quantum chromodynamics (QCD) effects in vector-boson production. This paper presents for the first time the measurement of the full set of angular coefficients together with the differential cross-section as a function of the transverse
momentum of the W boson, in the full phase space of the decay leptons. The measurements are performed separately for the W− and W+ channels. The analysis uses proton–
proton collision data recorded by the ATLAS experiment at the Large Hadron Collider in 2017 and 2018, during special low-luminosity runs with a reduced number of interactions
per bunch crossings (pile-up). The data correspond to an integrated luminosity of 338 pb−1 at a centre-of-mass energy of √s = 13 TeV. The low pile-up environment provides
excellent experimental conditions for high-precision measurements ofW-boson production. All results agree with theoretical predictions incorporating finite-order QCD corrections
up to order α2S.
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Aad, G.; Aakvaag, Erlend; Abbott, B.; Abdelhameed, S.; Abeling, K. & Abicht, N. J.
[Show all 2,850 contributors for this article]
(2026).
Search for long-lived charginos and τ-sleptons using final states with a disappearing track in pp collisions at √s=13 TeV with the ATLAS detector.
Journal of High Energy Physics (JHEP).
ISSN 1126-6708.
2026(7).
doi:
10.1007/JHEP07(2026)152.
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This paper reports a search for decays of long-lived charginos or τ-sleptons to final states containing a short disappearing track, a single high-energy jet, and missing transverse momentum. The search uses 137 fb−1 of data from 13 TeV proton–proton collisions recorded by the ATLAS detector during Run 2 of the LHC. Multiple search regions are defined, all requiring the presence of a track reconstructed from either three or four measurements in the innermost layers of the ATLAS detector. Regions with tracks having only three measurements are further characterised by the absence or presence of a low-energy charged pion reconstructed using a dedicated algorithm, leveraging machine learning. Data-driven methods are used to estimate the background contributions in the search regions. No significant excesses are found and 95% CL lower limits are placed on the masses of charginos and τ-sleptons in the lifetime range 0.01–10 ns. Observed (expected) mass limits of up to 225 GeV (250 GeV) are set for pure-higgsino charginos in scenarios with lifetimes below 0.03 ns, where the electroweakino mass splitting is entirely due to loop corrections involving the Standard Model bosons, and up to 720 GeV (840 GeV) for charginos with a lifetime of around 1 ns. For wino production, charginos with masses up to 880 GeV (1020 GeV) are excluded for lifetimes of around 1 ns. For τ-sleptons with lifetimes of around 1 ns, masses are excluded up to 320 GeV (390 GeV) in Constrained Minimal Supersymmetric Standard Model scenarios and 300 GeV (380 GeV) in Gauge-Mediated Supersymmetry-Breaking scenarios.
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Zwalinski, L.; Zorbas, T. G.; Zografos, A.; Zoch, K.; Zoccoli, A. & Živković, L.
[Show all 2,855 contributors for this article]
(2026).
Breaking barriers: the impact of ATLAS Virtual Visits in science communication.
The European Physical Journal Plus.
141(7).
doi:
10.1140/epjp/s13360-026-07771-w.
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The ATLAS Collaboration at CERN’s Large Hadron Collider is at the forefront of particle physics research and is equally committed to bridging the gap between cutting-edge science and the wider public. Since 2010, the ATLAS Virtual Visits programme has provided live, interactive tours of the ATLAS detector and control room to global audiences in their language, without the need to travel. The programme has grown significantly since its inception, as demonstrated by quantitative data collected since January 2019 and case studies of large-scale implementations in Brazil and Greece. The impact on individual participants is also discussed.
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Aad, G.; Aakvaag, Erlend; Abbott, B.; Abdelhameed, S.; Abeling, K. & Abicht, N. J.
[Show all 2,928 contributors for this article]
(2026).
Measurement of the azimuthal anisotropy of charged particles in √sNN = 5.36 TeV<sup>16</sup>O+<sup>16</sup>O and<sup>20</sup>Ne+<sup>20</sup>Ne collisions with the ATLAS detector.
Physical Review C.
ISSN 2469-9985.
113(4).
doi:
10.1103/XQXZ-8BHF.
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Petersen, Clemens; Vogt, Sofie; Fernandez, Javier Garcia; Vines, Lasse; Kano, Taisei & Grundmann, Marius
[Show all 8 contributors for this article]
(2026).
Single-domain, semiconducting κ-Ga2O3 grown on isostructural ε-GaFeO3 templates.
Applied Physics Letters.
ISSN 0003-6951.
129(17).
doi:
10.1063/5.0343866.
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The epitaxial growth of a phase-pure, single-domain, semiconducting κ-Ga2O3 thin film is demonstrated. Multiferroic ε-GaFeO3, being isostructural to κ-Ga2O3, was used as a substrate and was initially covered by a high-temperature MIST-CVD κ-Ga2O3 seed layer. Subsequently, tin-assisted pulsed laser deposition at 550 °C was applied to grow the single-crystalline epilayer with a thickness of 400 nm. The structural properties were investigated by x-ray diffraction and transmission electron microscopy. A reciprocal space map revealed that the κ-Ga2O3 layer sustains residual strain and is only partially relaxed. Consistently, misfit dislocations were observed, indicating ongoing but incomplete strain relaxation. Secondary ion mass spectrometry confirmed efficient Sn incorporation and revealed Fe diffusion from the ε-GaFeO3 substrate. The Fe impurities segregate predominantly at the advancing growth front, resulting in only moderate bulk compensation of the κ-Ga2O3/ε-GaFeO3 layer. Temperature-dependent in-plane transport measurements revealed freeze out of free electrons with activation energies of Ea,1=48 meV and Ea,2=253 meV at intermediate and high temperatures, respectively. No measurable in-plane conductivity was observed for a reference sample deposited on c-plane sapphire, which exhibited in-plane rotational domains and nanocolumnar growth. These results demonstrate that epitaxial growth on isostructural ε-GaFeO3 enables single-crystalline, semiconducting κ-Ga2O3 and establishes the κ-Ga2O3/ε-GaFeO3 heterostructure as a promising platform for exploring polarization-charge-induced two-dimensional electron gases in multifunctional ferroelectric/ferrimagnetic oxide systems.
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Salucci, Clara Bertinelli; Reiersrud, Hedvig Borgen; Read, A. L.; Kvellestad, Anders & Bin, Riccardo De
(2026).
The asymptotic distribution of the likelihood ratio test statistic in two-peak discovery experiments.
European Physical Journal C.
ISSN 1434-6044.
86(10).
doi:
10.1140/epjc/s10052-026-16439-9.
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Abstract Likelihood ratio tests are widely used in high-energy physics, where the test statistic is usually assumed to follow a chi-squared distribution with a number of degrees of freedom specified by Wilks’ theorem. This assumption breaks down when parameters such as signal or coupling strengths are restricted to be non-negative and their values under the null hypothesis lie on the boundary of the parameter space. Based on a recent clarification concerning the correct asymptotic distribution of the likelihood ratio test statistic for cases where two of the parameters are on the boundary, we revisit the the question of significance estimation for two-peak signal-plus-background counting experiments. In the high-energy physics literature, such experiments are commonly analyzed using Wilks’ chi-squared distribution or the one-parameter Chernoff limit. We demonstrate that these approaches can lead to strongly miscalibrated significances, and that the test statistic distribution is instead well described by a chi-squared mixture with weights determined by the Fisher information matrix. Our results highlight the need for boundary-aware asymptotics in the analysis of two-peak counting experiments.
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Grevillot, Loïc; Jäkel, Oliver; Qubala, Abdallah; Horn, Julian; Aitkenhead, Adam H. & Liang, Xiaoying
[Show all 32 contributors for this article]
(2026).
ESTRO-EPTN guidelines for independent dose calculation and log file-based patient-specific quality assurance in scanned particle therapy.
Physics and imaging in radiation oncology (PIRO).
41,
p. 1–8.
doi:
10.1016/j.phro.2026.101109.
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Jin, Yaqi; Kotova, Daria; Lanabere, Vanina; Spicher, Andres; Clausen, Lasse & Buchert, Stephan
[Show all 9 contributors for this article]
(2026).
Does bursty bulk flow affect F-region irregularities in the auroral ionosphere?
Advances in Space Research.
ISSN 0273-1177.
doi:
10.1016/j.asr.2026.09.075.
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In this paper, we investigate the relationship between bursty bulk flows (BBFs) in the magnetotail and ionospheric irregularities at Swarm altitude in the nightside auroral ionosphere. A database of 487 BBF-Swarm conjunction events during 2017–2024 is constructed by mapping BBFs to the ionosphere using Tsyganenko magnetic field models and selecting Swarm passes within 200 km and 15 min of the mapped BBF centroids. We make use of relevant Swarm datasets, including plasma density, temperature, density fluctuations and gradients at multiple scales, field-aligned currents (FACs), and cross-track ion velocities. Two case studies in the Northern and Southern Hemispheres show that BBFs can coincide with enhanced FACs, strong and rapidly varying ion flows, and intensified F-region ionospheric irregularities. However, enhanced F-region irregularities can also occur outside of the BBF conjunction time. Before presenting the statistical study, we show that ionospheric irregularities are highly variable and depend on solar and geomagnetic activity, local time, and season. The statistical comparison of upper-quartile F-region irregularity parameters near BBFs with the surrounding nightside auroral region shows only negligible differences. However, there are also large extreme values of differences between BBF and background, where the BBF intervals show clear enhancement of more than 100%. We further conduct a superposed epoch analysis. Though the analysis shows that BBFs have a clear FAC signature, there is no distinct enhancement of F-region irregularity indices near BBFs as compared to the nightside auroral region. These results suggest that while BBFs can locally generate or intensify F-region irregularities, their statistical impact is not stronger than that of other auroral processes. Uncertainties in BBF footpoint mapping, limitations in auroral region identification, uneven sampling over the solar cycle, season, and longitude, and the presence of multiple unresolved BBFs and auroral structures likely contribute to the weak statistical signature. Overall, BBFs are one of several contributors to F-region irregularities at auroral latitudes, but their effect cannot be uniquely isolated from the general nightside auroral environment in F-region irregularities observed by Swarm.
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Hunnestad, Kasper; Dubourdieu, Catherine; Gruverman, Alexei & Meier, Dennis
(2026).
Atom Probe Tomography as an Emerging Tool for Understanding Defect‑Driven Mechanisms in HfO<inf>2</inf>‑Based Ferroelectrics.
Advanced Functional Materials.
ISSN 1616-301X.
36(81).
doi:
10.1002/adfm.77492.
Full text in Research Archive
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Avsajanishvili, Olga & Grøn, Øyvind Geelmuyden
(2026).
The Linear Response of the CMB-Inferred Hubble Constant to Perturbations in the Expansion History.
Universe.
12(9).
doi:
10.3390/universe12090286.
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We develop a model-independent response-window formalism that describes how small perturbations of the cosmological expansion history around that of the standard ΛCDM model affect the Hubble constant, H0, inferred from the cosmic microwave background (CMB) acoustic-scale constraint. The formalism is independent of the physical origin of the perturbation, which may, for example, arise from a modification of the dark-energy contribution to the expansion history. By considering perturbations at fixed physical matter and radiation densities, we derive a first-order functional relation in which the response is determined by a single projection of the expansion-history perturbation onto a signed response kernel. The kernel is normalized by the difference between the pre-recombination sound-horizon and post-recombination distance contributions, with the latter dominating for the fiducial cosmology. We show that the resulting response window is strongly localized at late times, with an effective redshift zeff ≃ 0.46 and a dominant contribution concentrated near the present epoch. Numerical tests demonstrate substantial sensitivity to the temporal profile of smooth perturbations, while perturbations with identical kernel projections are linearly equivalent in their effect on the inferred H0. The formalism provides a model-independent framework for quantifying and comparing the CMB response to modifications of the late-time expansion history.
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Myhrehagen, Henning Vinjusveen; Odden, Tor Ole Bigton & Henriksen, Ellen Karoline
(2026).
Integrating Programming into Norwegian Upper-Secondary Science Instruction: Teachers’ Backgrounds and Perceived Challenges.
Nordic Studies in Science Education (NorDiNa).
ISSN 1504-4556.
23(2),
p. 234–254.
doi:
10.5617/nordina.12186.
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In 2020, Norway introduced a science curriculum reform integrating programming into upper-secondary natural science, biology, chemistry, and physics subjects. However, many teachers had limited programming experience, and it is therefore of interest to investigate how they have implemented it. We surveyed 260 science teachers three years after initial implementation to assess their programming backgrounds and perceived challenges with integrating programming into their instruction. We identified significant disciplinary differences: Physics teachers had the strongest programming foundation, while biology, chemistry, and natural science teachers struggled with learning programming and finding relevant disciplinary applications. Across all subjects, teachers cited insufficient knowledge among themselves and their students, lack of time, and limited resources as major challenges. While professional development (PD) courses have helped some get started, access to these courses is limited. Based on these results we argue that to ensure effective and continued programming integration, teachers need targeted, subject-specific PD that addresses both programming skills, science applications, and pedagogical strategies.
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Younesi, Ali Tayefeh; Luu, Minh Tuan; Linderälv, Christopher; Zalandauskas, Vytautas; Bathen, Marianne Etzelmüller & Son, Nguyen Tien
[Show all 10 contributors for this article]
(2026).
Unraveling the Electronic Structure of Silicon Vacancy Centers in 4H-SiC.
Advanced Functional Materials.
ISSN 1616-301X.
36(58).
doi:
10.1002/adfm.76183.
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Point defects in silicon carbide (SiC), particularly the negatively-charged silicon vacancy (V−Si) in 4H-SiC, are leading candidates for scalable quantum technologies due to their favorable spin–optical properties and compatibility with industrial semiconductor fabrication processes. Comprehensive knowledge of a defect's electronic structure is essential for interpreting spin–optical dynamics and for the reliable design and optimization of defect-based quantum devices. Despite extensive study, our knowledge of the electronic structure of V−Si is limited since key excited-state manifolds have remained inaccessible to conventional steady-state spectroscopy. In this study, transient absorption spectroscopy is utilized to probe non-equilibrium electronic transitions of V−Si and to uncover previously unobserved excited states. The first direct observation of the elusive V2′ quartet transition is presented, with its broad spectral signature attributed to nonadiabatic vibronic coupling. Within the spin-doublet manifold, which is central to optically detected magnetic resonance (ODMR) but has remained unresolved spectroscopically, multiple optical transitions are identified. The complete electronic level structure in the relevant energy range is elucidated by combining polarization-resolved spectroscopy, group-theoretical analysis, quantum embedding calculations, and first-principles optical lineshape modeling. Collectively, these results provide a microscopic understanding of the V−Si electronic structure. Our approach also establishes a general framework for resolving and understanding complex excited-state manifolds in wide-bandgap color centers.
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Shafizadeh, Danial; Ghezellou, Misagh; Bobal, Viktor; Vines, Lasse; Ul-Hassan, Jawad & Jokubavicius, Valdas
[Show all 8 contributors for this article]
(2026).
Spin-active chlorine-related centers in 4H-SiC with telecom band emissions.
Applied Physics Letters.
ISSN 0003-6951.
129(10).
doi:
10.1063/5.0351442.
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In chlorine-implanted 4H-SiC, a photoluminescence (PL) band with four narrow zero-phonon lines (ZPLs) in the range of 1350–1540 nm, labeled Cl1–Cl4, is observed. Among these, two ZPLs in the telecom C-band, Cl1 and Cl2 at 1539.2 and 1533.3 nm, respectively, exhibit high Debye–Waller factors (∼59% and ∼41%, respectively). Optically detected magnetic resonance confirms that the Cl-related center is spin active and stable at room temperature with zero-field splitting in the range of 1.0–1.4 GHz. The combined favorable optical and spin properties and advantages of an industrially established SiC material suggest this Cl-related center to be a highly promising candidate for scalable quantum networks.
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Medeiros, Helton Goncalves de; Ulibarri, Agatha Christie; Kumar, Piyush; Martins, Maria Mendes; Bathen, Marianne Etzelmüller & Grossner, Ulrike
(2026).
Postprocessing lattice strain in 4H-SiC.
Physical Review Applied.
26.
doi:
10.1103/tnjl-xzgr.
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Processing steps, such as thermal oxidation, creation of p- and n-doped regions via ion implantation, and postoxidation and postimplantation annealing, are essential for successful and reliable fabrication of devices based on 4𝐻-SiC. These processing steps are known to introduce crystalline defects or even modifications within the SiC base material that can potentially compromise device operation and reliability. In this work, we systematically study the strain introduced in the 4𝐻-SiC crystal by SiC-specific manufacturing methods. The results show that tensile strain is present after ion implantation, thermal oxidation, and subsequent annealing processes. Interestingly, aluminum implanted samples show compressive strain near the surface in addition to the presence of an additional Raman signature, while nitrogen and phosphorus implanted samples experience tensile strain. Density functional theory calculations were performed to corroborate the experimental data and connect the type of strain to the microscopic impact that different dopants have on the SiC lattice. These results contribute to the understanding of processing-induced modifications within the crystal and show that Raman spectroscopy is a powerful tool to assess modifications to the 4𝐻-SiC crystal.
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Snedker-Nielsen, Arnulf J.; Gongora, David Rivas; Madsen, Magnus L.; Christiansen, Christian H.; Piehorsch, Eike L. & Augustesen, Mathias Ø.
[Show all 16 contributors for this article]
(2026).
Colour Centre Formation in Silicon-On-Insulator for On-Chip Photonic Integration.
Advanced Optical Materials.
14.
doi:
10.1002/adom.71387.
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Color centers in silicon have great potential as single photon sources for quantum technologies. Some of them – like the T center – also possess optically-active spins that enable spin-photon interfaces for generating entangled photons and multi-spin registers. This paper explores the generation of several types of color centers in silicon for mass-manufacturable silicon-on-insulator quantum devices. We investigate how different processes in the device development affect the presence of the quantum emitters, including thermal annealing and fabrication steps for optical nanostructures. The study reveals coupled formation dynamics between different color centers, identifies optimal parameters for annealing processes, and reports on the sensitivity to annealing duration and nanofabrication procedures for photonic integrated circuits. Furthermore, we observe signals from unidentified color centers, which we suggest originate from the CN center.
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Ousdal, Erlend Lemva; Bathen, Marianne Etzelmüller; Rongve, Anna Stray; Pedersen, Benedicte Allum; Selnesaunet, Gard Momrak & Kjeldby, Snorre Braathen
[Show all 9 contributors for this article]
(2026).
Mapping Emission Directionality of Color Centers in Silicon Carbide Microparticles.
ACS Nanoscience Au.
6(4),
p. 523–529.
doi:
10.1021/acsnanoscienceau.5c00187.
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Color centers in semiconductors constitute a promising platform for developing quantum technology applications. To fully mature the platform, strict requirements on controlling the directionality of photon emission must be met. This work presents a method for studying and evaluating geometric features that can impact the directionality of emission from color centers in semiconductors by leveraging different nanostructures in silicon carbide (SiC) microparticles. Using spectrally resolved and angle-resolved cathodoluminescence measurements, we demonstrate decoupling of the color center emission from other luminescence sources and investigate how geometric features affect emission directionality. Combined with finite difference time domain simulations, geometric effects on emission directionality in the SiC particles are explored using simulations of luminescence from idealized geometries. As such, we present a holistic approach to evaluate the directionality of emission from color centers, independent of the material system, by combining experimental measurements and numerical simulations, using SiC as a benchmark case.
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Yuan, Zimo; Metreveli, Alex; Vines, Lasse; Samperi, Orazio; Ghezellou, Misagh & Ul-Hassan, Jawad
[Show all 7 contributors for this article]
(2026).
Investigating the Temperature Dependence of Charge Carrier Lifetime in Low-Doped Epitaxial 4H-SiC Layers.
Defect and Diffusion Forum.
ISSN 1012-0386.
452,
p. 45–51.
doi:
10.4028/p-xjp7QK.
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In this paper, the temperature dependence of charge carrier lifetimes in n-type 4H-SiC epitaxial layers is studied in a temperature range of 300-500 K. It is assumed that shallow (B) and deep (D) boron-related defects are the dominating lifetime killers in as-grown epitaxial layers. The thermodynamic behavior of these two types of defects is obtained from DLTS measurements, and implemented in the Shockley-Read-Hall (SRH) model to calculate lifetimes, using Gibbs free energies to describe the accurate temperature dependence for capture and emission processes of the defects. Calculation results show that the lifetimes controlled by shallow boron defects increase with increasing temperature, while D-defects give the opposite temperature dependence. The theoretical results are also compared to measured data from 10 kV 4H-SiC PiN-structures, showing that the temperature dependence of the effective lifetime can be changed by proton implantations, which gives rise to additional Z1/2 defects that have similar temperature effects on lifetimes as D-related defects.
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Danieli, Krubeal & Lepperød, Mikkel Elle
(2026).
Flexible navigation with neuromodulated cognitive maps.
PLoS Computational Biology.
ISSN 1553-734X.
22(7),
p. 1013487–1013487.
doi:
10.1371/journal.pcbi.1013487.
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Animals develop specialized cognitive maps during navigation, constructing environmental representations that facilitate efficient exploration and goal-directed planning. The hippocampal CA1 region is implicated as the primary neural substrate for cognitive mapping, housing spatially tuned cells that adapt based on behavioral patterns and internal states. Computational approaches to modeling these biological systems have employed various methodologies. Although labeled graphs with local spatial information and deep neural networks have provided computational frameworks for spatial navigation, significant limitations persist in modeling one-shot adaptive mapping. We introduce a biologically inspired place cell architecture that develops cognitive maps during exploration of novel environments. Our model implements a simulated agent for reward-driven navigation that forms spatial representations online. The architecture incorporates behaviorally relevant information through neuromodulatory signals that respond to environmental boundaries and reward locations. Learning combines rapid Hebbian plasticity, lateral competition, and targeted modulation of place cells. Analysis of the model across a variety of environments demonstrates that online map formation and reward-directed navigation can emerge within a single simulated trial, without the multi-epoch training typically required by reinforcement-learning approaches. The simulation results show that the agent successfully explores and navigates to target locations in various environments, adapting when reward positions change. Analysis of neuromodulated place cells reveals dynamic changes in neuronal density and place field size after behaviorally significant events. These findings align with experimental observations of reward effects on hippocampal spatial cells while providing computational support for the efficacy of biologically inspired approaches to cognitive mapping.
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Totland, Lasse; Bendiksen, Bård Andre; Nordén, Einar Sjaastad; Hauge-Iversen, Ida Marie; Bergo, Kaja Knudsen & Zhang, Lili
[Show all 8 contributors for this article]
(2026).
Strain Rate Angle Distribution as an Indicator of Post-Infarct Myocardial Remodeling: Proof-of-Concept of a Novel Application of the MRI Derived Strain Rate Tensor Field.
Magnetic Resonance in Medicine.
ISSN 0740-3194.
p. 1–14.
doi:
10.1002/mrm.70607.
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Lunde, Jenny; Anderson, E.K.; Bartulović, P.; Baudot, J.; Berdalović, I. & Dorokhov, A.
[Show all 13 contributors for this article]
(2026).
Exploring effects of geometrical parameters for CASSIA, a monolithic sensor with internal amplification.
Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment.
ISSN 0168-9002.
1091.
doi:
10.1016/j.nima.2026.171784.
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Tracking in future High Energy Physics collider experiments requires high timing and high spatial resolution while keeping the material budget low. The CMOS Active SenSor with Internal Amplification (CASSIA) project addresses these requirements by developing a monolithic CMOS sensor with internal amplification. The sensor is designed to have two operational modes, a low gain amplification region with a gain in the range of 10–100 before breakdown, and a single photon avalanche mode with gain in the order of 1000 after breakdown. In this article, changes to the gain layer radius and implant structures are analyzed, showing a difference in breakdown voltage of tens of volts depending on implant structures and gain layer radius. Dark count rates also show a clear dependence on the combination of n+-electrode and gain layer implants.
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Pernegger, H.; Anderson, E.K.; Bartulović, P.; Berdalović, I.; Brown, M. Giroux de Foiard & Haberl, S.
[Show all 11 contributors for this article]
(2026).
First results of a monolithic active pixel sensor with internal signal gain fully integrated in a 180 nm CMOS technology.
Journal of Instrumentation (JINST).
21.
doi:
10.1088/1748-0221/21/05/p05022.
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Dense tracking environments in experiments at CERN's High-Luminosity LHC and future FCC experiments call for an increased use of timing information in addition to the position measurement of pixel detectors. This adds one dimension to the information available, and is essential for pile-up mitigation at high luminosity. The CASSIA sensor project ( C MOS A ctive S en S or with I nternal A mplification) focuses on the development of pixel matrices with internal charge multiplication, based on monolithic CMOS sensor technologies, suitable for application as charged particle tracking and timing detectors. CMOS sensors with in-pixel internal amplification would provide higher signal amplitudes, an improved signal-to-noise ratio, better time resolution and increased sensitivity, making them attractive for high-radiation environments. Their monolithic integration in small pixels reduces the parallel capacitance presented to a front-end amplifier and the power dissipation making it suitable for fine-pitch low-power detectors. Fast signal rise time due to internal charge amplification improves the response time and timing resolution, all of which make such a technology attractive for future 4D tracking applications in HEP experiments. This paper presents the first results of the CASSIA sensor, a novel MAPS which uses gain layers fully integrated in a 180nm imaging process to achieve internal signal amplification. In the first measurements presented here we demonstrate the gain behaviour of different pixel implant designs and show that the sensor can be operated as LGAD sensor with low gain in proportional mode at lower voltages and as SPAD sensor at higher voltages.
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Chang, Christopher Jackson; Farmer, Benjamin; Fowlie, Andrew & Kvellestad, Anders
(2026).
Exact inference from noisy simulations in collider physics.
Physical Review D.
ISSN 2470-0010.
113(7).
doi:
10.1103/2d39-gsjp.
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Stange, Marit Synnøve Sæverud; Bumke, Lars; Quandt, Eckhard; Kušnír, Jakub; Grabec, Tomáš & Seiner, Hanuš
[Show all 11 contributors for this article]
(2026).
Screening for new elastocaloric materials in a compositionally graded NiCuTiZr thin film.
Materialia.
50,
p. 1–16.
doi:
10.1016/j.mtla.2026.102896.
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NiTi-based shape memory alloys can be used as the active material in elastocaloric cooling devices. For optimal performance, they should simultaneously exhibit high reversibility and low temperature hysteresis, which can be achieved by ensuring that the middle eigenvalue of the primary stretch matrix λ2=1. Also, an adequate transformation temperature and a high enthalpy of transformation are required. In this study, a systematic screening for highly reversible shape memory alloys was performed, using compositionally graded Ni-Cu-Ti-Zr thin films generated by magnetron sputtering. Based on experimental data from the literature, a model predicting λ2 from the quaternary film compositions indicated a range of targeted compositions with λ2=1. The properties of the thin-film compositions were experimentally investigated to corroborate the theoretical possibilities. Martensitic phase transformations were observed with differential scanning calorimetry, demonstrating a systematic change in transformation temperatures with composition. X-ray diffraction confirmed a transition
between B2 austenite and B19’ martensite structures, similar to binary NiTi compounds. The targeted compositions did not exhibit the expected temperature-driven phase transformations with low hysteresis. Tensile testing revealed superelastic behaviour, but the samples were intrinsically brittle with large hysteresis and mechanical instability. This was explained by phase separation and the formation of Ti2Ni- and Ni4Ti3-like minority phases. Despite the failure to demonstrate new shape memory alloys with high reversibility, the study suggests a path to efficient searches for new alloys with novel functional properties.
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Grandcolas, Mathieu; Løvoll, Marte; Dahl, Øystein; Thøgersen, Annett; Svenum, Ingeborg-Helene & Wenckstern, Holger Von
[Show all 7 contributors for this article]
(2026).
Rapid thermal processing of photoanodes for solar water splitting: status, challenges and opportunities.
Solar Energy Materials and Solar Cells.
ISSN 0927-0248.
309,
p. 1–9.
doi:
10.1016/j.solmat.2026.114728.
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Rapid thermal processing (RTP) is gaining attention as an efficient alternative to conventional annealing of materials for photoelectrochemical (PEC) water splitting. By delivering ultrafast heating and precise temperature control, RTP introduces non-equilibrium conditions that enable metastable phase formation, defect engineering, and interfacial control, while preserving transparent conductive oxides (TCOs) essential for PEC architectures. These advantages improve crystallinity, activate dopants, and enhance interfacial quality without the drawbacks of prolonged furnace treatments. Recent studies report two- to fourfold increases in photocurrent density and negative onset potential shifts up to 300 mV for RTP-treated photoanodes, highlighting RTP's potential to accelerate PEC performance toward industrial benchmarks. Despite these advantages, RTP remains underutilized in PEC research, with challenges in process optimization, atmosphere control, and scalability still unresolved. This review summarizes current progress on RTP for several oxide photoanodes, compares its performance with that of conventional annealing processes, and discusses mechanistic insights. Future directions include hybrid thermal strategies, real-time diagnostics, and data-driven design to enable scalable PEC device manufacturing and sustainable solar hydrogen production.
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Reis, Paula Kozlowski Pitombeira; Flekkøy, Eirik Grude; Toussaint, Renaud & Måløy, Knut Jørgen
(2026).
Linear response theory of front back-contraction during a single Haines jump.
Journal of Fluid Mechanics.
ISSN 0022-1120.
1041.
doi:
10.1017/jfm.2026.11960.
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We study the linear response of a fluid–fluid interface in a porous medium subjected to a localised, transient perturbation. A single pore is driven out of mechanical equilibrium by a small displacement, initiating a back-contraction of the interface. Assuming negligible total flow, the interface relaxes with a time- and space-dependent profile h(x,t), modelled for a flat geometry. This set-up reflects conditions achievable experimentally using a localised heterogeneity in pore-throat sizes. We determine the evolving interface shape during the relaxation process, together with the associated pressure and velocity fields, using both analytical calculations and pore-network simulations.
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Mikheenko, Pavlo
(2026).
Artificial quantum brain: A bold proposal.
Low Temperature Physics.
ISSN 1063-777X.
52(7),
p. 900–904.
doi:
10.1063/10.0044252.
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The paper discusses the possibility of building an elemental unit of an artificial quantum brain using self-assembly, featuring resonant synchronization and the spontaneous development of an action-potential response to coherent electromagnetic radiation. This unit will be suitable for incorporation into bionic robotic systems and/or natural biological organisms. It is proposed that the unit be formed through the self-assembly of superconducting microtubules on a rigid polymer scaffolding, with a spatial periodicity of 9 μm, to allow synchronization by infrared radiation at this wavelength, making it compatible with the natural brains of biological organisms. The paper describes the available experiments on the controlled self-assembly of such microtubules. Additionally, it suggests methods for training the artificial brain unit and exploring its emerging quantum consciousness.
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Ali, Ahmed Farag; Inan, Nader; Laukkonen, Ruben & Mikheenko, Pavlo
(2026).
A Coherence–Dissipation Framework for Brain Dynamics and Consciousness.
Entropy.
28(10).
doi:
10.3390/e28101074.
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We develop a theoretical proposal linking vacuum stability and brain dynamics through superconductivity-inspired coherence, symmetry reduction, and the thermodynamic stabilization of low-entropy regimes. We take an unbroken SU(3) structure as a candidate stable residue of the low-temperature vacuum. At the neural level, we formulate a coarse-grained analog in which a two-fluid model with dissipative and coherence-supporting components describes brain dynamics. Specifically, the coherence-supporting component is proposed as a possible basis for the efficient binding and integration required to sustain a stable, unified conscious state. The proposal offers a common geometric language for relating physics and neuroscience with falsifiable signatures in coherence and state-dependent transitions. The main technical contribution is a computational algebraic model of conscious-state dynamics, where neural data are mapped to reconstructed state trajectories. Effective generators are inferred from those trajectories, and the two-fluid split is tested as a Cartan–root decomposition of su(3), with a rank-two commuting sector for coherence-preserving balance and six root directions for state transitions. This structure can be tested on neural data and contrasted with alternative dynamical models.
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Holen, Gaute Arnesson; Mishra, Rinku; Miyake, Y. & Miloch, Wojciech Jacek
(2026).
Ion trapping around small positively charged objects in magnetized plasma.
Physics of Plasmas.
ISSN 1070-664X.
33(5).
doi:
10.1063/5.0309574.
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We present a novel trapping mechanism for ions around small positively charged objects in magnetized plasma. Here, the Larmor radius is larger than the object, but approximately equal to the characteristic radial length of the object's electrostatic structure. The resulting steady state solution from state-of-the-art particle-in-cell simulations shows a bipolar electric field around the object, with a density enhancement in the quasi-neutral region. Test particle simulations explore the mechanism behind the ion trapping by focusing on single-particle-motion, and transforming the particles to gyro-center, Larmor radius space. We also observe a kinetic energy gradient in the quasi-neutral region, where the ions organize themselves with respect to distance from the object according to their velocity, where the gyro-centers of particles are nearly coincident with the object's position. This leads to a shift in the velocity distribution. Analysis of test particles' temporal evolution in the gyro-center, Larmor radius space reveals regions of instability and stability, which correspondwell with the density enhancement and ion depletion. The results are similar for spherical and cylindrical objects, suggesting that the trapping mechanism is fundamental. These findings have implications for understanding plasma interactions with small objects, with potential applications in space physics, fusion devices, and plasma diagnostics.
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Harris, Caley M.; Spyrou, Artemis; Denissenkov, Pavel; Herwig, Falk; Richard, Andrea L. & Uthayakumaar, Sivahami
[Show all 23 contributors for this article]
(2026).
Influence of neutron-capture reactions on the nucleosynthesis of strontium.
Communications Physics.
9(1).
doi:
10.1038/s42005-026-02713-5.
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The astrophysical intermediate neutron-capture process (i process) has been reinvoked in recent years to describe stellar observations that cannot be explained by the traditional nucleosynthesis processes. Despite its success, significant uncertainties still remain including the exact astrophysical conditions and site, as well as the nuclear physics input. Available i-process models strongly underproduce the abundance of strontium (Sr) compared to observational data, while successfully describing neighboring elements, like yttrium (Y) and zirconium (Zr). This discrepancy has been attributed to nuclear physics uncertainties, specifically to the unconstrained reaction rate of the neutron-capture on the isotope krypton-88. Here we present an experimental investigation of this reaction and show that our result provides a possible solution to the aforementioned Sr underproduction in i-process models.
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Zwalinski, L.; Zou, W.; Zormpa, O.; Zorbas, T. G.; Zoch, K. & Zoccoli, A.
[Show all 2,931 contributors for this article]
(2026).
Erratum to: Precision measurement of the B<sup>0</sup>meson lifetime using B<sup>0</sup>→ J/ ψ K<sup>*0</sup>decays with the ATLAS detector (The European Physical Journal C, (2025), 85, 7, (736), 10.1140/epjc/s10052-025-14232-8).
European Physical Journal C.
ISSN 1434-6044.
86(1).
doi:
10.1140/epjc/s10052-025-15188-5.
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Zwalinski, L.; Zormpa, O.; Zorbas, T. G.; Zografos, A.; Zoch, K. & Zoccoli, A.
[Show all 2,939 contributors for this article]
(2026).
Erratum: The environmental impact, carbon emissions and sustainability of computing in the ATLAS experiment (The European Physical Journal C, (2025), 85, 12, (1397), 10.1140/epjc/s10052-025-14976-3).
European Physical Journal C.
ISSN 1434-6044.
86(3).
doi:
10.1140/epjc/s10052-026-15357-0.
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Zwalinski, L.; Zormpa, O.; Zorbas, T. G.; Zografos, A.; Zoch, K. & Zoccoli, A.
[Show all 2,854 contributors for this article]
(2026).
Publisher Correction: Calibration of the jet energy scale and resolution of small-radius jets using semileptonic tt¯ events with the ATLAS detector.
European Physical Journal C.
ISSN 1434-6044.
86(10).
doi:
10.1140/epjc/s10052-026-16348-x.
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In the originally published article, several typographical and formatting errors were identified. In the PDF version, on page 10 (bottom left), the terms “POWHEGinterfaced” and
“POWHEGsettings” should read “POWHEGinterfaced” and “POWHEG settings”, respectively. In the online version, instances of “T{eV}” and “G{eV}” throughout the text should
read “TeV” and “GeV”, respectively. The publisher regrets these errors and any inconvenience they may have caused.
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Dahle, Lars & Holm, Sverre
(2026).
Leonhard Euler, den kreative matematikeren – med Sverre Holm (4:3).
doi:
https:/open.spotify.com/episode/7EAhDo185Ufb6e53LYNh0S.
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Episoden utforsker hvordan matematikeren Leonhard Euler forente banebrytende vitenskap med en tydelig kristen tro, og forsvarte Jesu oppstandelse og Bibelens troverdighet. Samtalen mellom fysiker Sverre Holm og teolog Lars Dahle drøfter også hvordan synet på forholdet mellom tro og vitenskap har preget ettertidens fremstilling av Euler.
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Bøe, Maria Vetleseter & Sørborg, Øystein
(2026).
Kjerner og stjerner.
Show summary
Vi presenterer «Kjerner og stjerner», en interaktiv, digital læringssti på viten.no om dannelse av grunnstoff i stjerner og stjernekollisjoner. viten.no/kjerner-og-stjerner
Målgruppe: Fysikk programfag
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Frøland, Mariann Carlsen; Langørgen, Amanda; Løvoll, Marte & Teien, Aurora
(2026).
Jenter og teknologi UiO 2026 - Besøk på MiNaLab.
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Dahle, Lars & Holm, Sverre
(2026).
Nicolaus Steno, Niels Steensen, det ukjente universalgeniet – med Sverre Holm (4:2).
doi:
https:/open.spotify.com/episode/0PfOkoyWjOWxwAtcG4FWpY.
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I denne episoden fortsetter Lars Dahle sine engasjerende samtaler med fysiker Sverre Holm om sentrale kristne naturforskere og deres tro. Denne gangen er det universalgeniet Nicolaus Steno (1638–1686) som er i fokus. Utgangspunktet for samtalene er boka Vitenskap med overtoner (2025).
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Boivinet, Xavier; Rukan, Isak Cecil Onsager; Gulla, Jan & Skaar, Johannes
(2026).
Ils ont essayé de couper un photon en deux | Epsiloon.
[Journal].
Epsiloon magazine.
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En théorie, c’est impossible –le photon est une particule élémentaire! Pourtant, de jeunes physiciens s’amusent à relever le défi.
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Bøe, Maria Vetleseter & Henriksen, Ellen Karoline
(2026).
Fysikk frå roterommet til klasserommet.
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I god roteromstradisjon slår vi eit slag for forsøk med enkelt utstyr for å skape undring, engasjement og læring i fysikk og fysikkdelen av naturfaget på Vg1. Sesjonen vil by på praktiske aktiviteter og eksempler på ulike måter å bruke forsøk i undervisninga på.
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Dahle, Lars & Holm, Sverre
(2026).
Veien fra «Den innbilte konflikten» til «Vitenskap med overtoner» - med Sverre Holm (4:1) - Apologetikkprofessoren | Podcast on Spotify.
doi:
https:/open.spotify.com/show/5z4NPFzfvCzX4SZf8VDuM4.
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I denne første episoden av sesong 4 av Apologetikkprofessoren møter vi Sverre Holm i samtale med Lars Dahle. Utgangspunkt for samtalen er Vitenskap med overtoner (2025, medforfatter Sven Aasmundtveit).
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Krichevskiy, Daniil; Kolesova, Helena; Melkild, Halvor; Bringmann, Torsten & Pomper, Joachim
(2026).
Beyond 3→2: Towards Realistic SIMP Dark Matter.
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Strongly interacting dark sectors with pseudo–Nambu–Goldstone bosons provide a versatile framework for sub-GeV dark matter. While the original SIMP paradigm emphasises number-changing 3 to 2 processes as the origin of the relic abundance, the phenomenology of pionic dark matter is considerably richer. Depending on the spectrum and couplings, the relic density can instead be controlled by 2 to 2 annihilations (WIMP-like regime), semi-annihilation channels involving vector mesons and further processes like \pi\pi\pi to \pi\rho. A consistent treatment therefore requires a framework that simultaneously captures pion dynamics, vector mesons, anomalous interactions, and portal effects.
We consider QCD-like dark sectors in which the dark matter candidates are pions stabilized by unbroken dark flavor symmetries. The effective theory is formulated using the Hidden Local Symmetry (HLS) approach. The HLS Lagrangian, supplemented by the gauged Wess–Zumino–Witten term, is constructed in a representation-independent manner and is applicable to complex, real, and pseudo-real fermion theories.
As a minimal benchmark, we focus on the pseudo-real symmetry-breaking pattern SU(2N_f)/Sp(2N_f) with Nf=2. We incorporate lattice results for Sp(N_c=4) to obtain realistic relations between m_\pi/f_\pi and m_\rho/m_\pi. A dark photon portal is included to maintain thermal equilibrium with the visible sector and to assess its impact on relic abundance and dark matter stability within the HLS framework.
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Reis, Paula Kozlowski Pitombeira; Moura, Marcel; Pierce, Kevin; Måløy, Knut Jørgen & Linga, Gaute
(2026).
Secondary imbibition in 2D porous media: The role of flow direction in trapping.
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Reis, Paula Kozlowski Pitombeira; Flekkøy, Eirik Grude; Toussaint, Renaud & Måløy, Knut Jørgen
(2026).
Linear Response Theory of Front-Back Contraction During a Single Haines Jump.
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Reis, Paula Kozlowski Pitombeira & Måløy, Knut Jørgen
(2026).
A Theoretical Model for Stable Drainage Fronts in 3D Porous Media.
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Boukraa, Mohamed Aziz; Karabiyik, Yücel; Austeng, Andreas; Holm, Sverre & Näsholm, Sven Peter
(2026).
Improved Full-Waveform Inversion in Time-Harmonic Elastography.
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Siem, Sunniva
(2026).
Presentation of The Norwegian Nuclear Research Centre (NNRC) and new BSc and MSc program in Nuclear Science.
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Siem, Sunniva & Pellegri, Luna
(2026).
Almost 15 years of fruitful Nuclear Physics collaboration between South Africa and Norway.
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Siem, Sunniva & Stavik-Døvle, Grete
(2026).
Studieprogrammene i nukleære fag: Studentenes kompetanse når de begynner på masteroppgaven.
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Tomkiv, Yevgeniya & Meir, Michaela Georgine
(2026).
15 Years After Fukushima - Advancing Science & Global Collaboration.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7440366580175187968.
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It is 15 years since a tsunami and earthquake devastated the coast of the Fukushima prefecture, and led to the accident at the Fukushima Daichi Nuclear Power Plant. A team led by NNRC's Deputy Director Prof. Deborah Oughton is currently visiting the Institute of Environmental Radioactivity at Fukushima University (IER) to attend the 12th Annual Symposium, “Fukushima Voices: 15 years of Nature and Humanity” (https://lnkd.in/egm5JVFz), and to discuss future collaboration in research and education.
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Hou, Jie; Martinsen, Ørjan Grøttem & Steen, Jørgen
(2026).
Towards an Affordable Dielectric
Spectroscopy System: Design
and Testing.
Universitetet i Oslo.
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A dielectric spectroscopy measurement system recovers a material’s complex permittivity, but commercial systems are costly; even the most affordable one found is a high-precision instrument at about 184 000 NOK, which limits access. To increase the availability of these systems, a more affordable, open version was developed with a custom probe, an open-source Vector Network Analyzer (VNA), and open-source post-processing for about 16 200 NOK. This thesis develops a post-processing pipeline that extracts permittivity from the VNA’s reflection coefficient, compares four extraction methods, and validates the results against a commercial reference for polar liquids across temperature. The affordable system tracked the reference closely, with more noise and weaker accuracy at higher frequencies. Overall, it delivered results comparable to the commercial reference at an order of magnitude lower cost, with the probe and cable the clearest targets for improvement.
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Storehaug, Ida Torkjellsdatter; Tveter, Trine Spedstad; Arsene, Ionut Cristian; Fionda, Fiorella Maria Celeste & Röhrich, Dieter Rudolf Christian
(2026).
The beauty of heavy-quark hadronization: Measurement of charged B meson production in proton–proton collisions at √ s = 13.6 TeV with the ALICE experiment.
Universitetet i Oslo.
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Quarks are fundamental building blocks of matter, but free quarks have never been observed. Instead, they are bound together in hadrons. Exactly how quarks combine into hadrons — a process called hadronization — is still not fully understood. Storehaug's thesis addresses the fundamental question: how do quarks form the hadrons we observe?
Beauty quarks are particularly useful for studying this process because they are heavy, allowing their production to be calculated with reasonable precision. After production, a beauty quark hadronizes and can form a B meson. Measuring the yield of B mesons therefore tests both calculations of beauty-quark production and our description of their hadronization.
The thesis presents the first measurement at the LHC of fully reconstructed charged B mesons in a previously unexplored kinematic region that is particularly sensitive to hadronization. The measurement uses data from proton–proton collisions collected with the ALICE experiment in 2023 and 2024. The main result is that the measurement is compatible with several models of beauty-quark production and hadronization, but that the theoretical calculations are not yet precise enough to distinguish between different hadronization mechanisms. This work contributes to a broader program of beauty-hadron measurements in ALICE, opening new possibilities for studying beauty-quark hadronization.
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Heines, Johannes Sørby; Görgen, Andreas; Modamio, Victor & Sahin, Eda
(2026).
On Triaxiality: Lifetime Measurements in Ruthenium, Molybdenum and Zirconium.
Universitetet i Oslo.
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The atomic nucleus is challenging to understand. The wave functions of the constituent nucleons come together to generate phenomena very similar to the deformation, rotation and vibration of macroscopic bodies. Change the number of protons or neutrons, however, and the quantum nature of the nucleus becomes apparent. This duality is at the centre of nuclear structure physics: macroscopic descriptions fail to capture the strong quantum effects inherent in the system, but equally, single-particle descriptions cannot account for the collective effects, which are just as apparent. The region of neutron-rich nuclei around mass 100 has garnered particular interest as a testing ground for theory due to its variety of shape-related phenomena: a sudden onset of deformation, with some nuclei showing mixing of two coexisting shapes, and some breaking axial symmetry, becoming triaxial.
This thesis reports on lifetime measurements made with the recoil-distance Doppler-shift method (rdds) in zirconium, molybdenum and ruthenium isotopes, and their implications for triaxial shape transitions, with particular focus on 108Mo and 109–112Ru. The experiment, performed at ganil, populated a large number of nuclides in the region, and used the large-acceptance mass spectrometer vamos++ to identify them event-by-event. The γ-raytracking detector array agata obtained high-statistics γ-spectra of the recoiling nuclei.
To analyse these data, we have developed a new method that aims to be more consistent with the physics of the measurement, and to produce more accurate uncertainty estimates. We show that this method yields results consistent with previously measured values, and use it to extract several previously unmeasured lifetimes. Our results are consistent with an increase in triaxiality in ruthenium, reaching near maximum asymmetry in 112Ru. We find slightly less substantial triaxiality in 108Mo.
We outline further opportunities for research on the dataset – many hitherto unknown lifetimes can still be extracted – and suggest several ways in which rdds analyses could be improved beyond what we have done here.
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Reistad, Ole; Siem, Sunniva; Fratoni, Massimiliano; Peterson, Per & Hisanawi, Josef A. H.
(2026).
Nøytronfysisk analyse av en hybrid maritim–landbasert brenselssyklus i fluoridsaltkjølte høytemperaturreaktorer
Nøytronfysisk oppførsel, avbrenningskompromisser og gjenbrukspotensial for delvis utbrente brenselskuler.
Universitetet i Oslo.
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Compact reactor cores generally suffer poorer neutron economy and therefore lower achievable fuel burnup than larger cores. This thesis examines a hybrid fuel cycle using Monte Carlo transport and depletion to potentially alleviate the burnup penalty in graphite-moderated Pebble Bed Reactors (PBRs). It does so by irradiating fuel in the 50 MWth gHermes core and transferring representative discharged compositions to a 280 MWth gFHR, where their remaining burnup capability was calculated up to the criticality limit. To isolate the effect of core size, the two models use the same fuel specification and reflector thickness and approximately equal packing fraction, power density, and power per pebble; total power, active volume, and pebble inventory were scaled by approximately the same factor.
Nine gHermes discharge thresholds BU = {15, 25, . . . , 95} MWd/kgHM were simulated with pebble-resolved depletion and explicit pebble and TRISO geometry. Of those nine streams, eight were then loaded into the large core.
In separate operation, the small core cannot sustain criticality past a burnup of 115 MWd/kgHM against 181 in the larger core, a shortfall of 36 %. A logarithmic five-factor decomposition attributes the reactivity gap primarily to degraded thermal utilization, with leakage a secondary contribution and higher resonance escape partially compensating the penalty. The smaller core also exhibits weaker fertile conversion, with the conversionratio gap widening as fuel depletes. Its vessel leakage per fission is 2.6 times that of the larger core. The compact core also exhibits an inverted radial thermal-flux profile, with reflector-returned neutrons raising the flux in the outermost fuel layers to the central level, consistent with a larger share of thermal absorption occurring outside the fuel.
Cumulative burnup per initially fresh pebble falls monotonically as transfer is delayed, from 176.0 to 121.4 MWd/kgHM. Transfer at 35 and 45 MWd/kgHM yields 160.0 and 152.5 MWd/kgHM against a 148 MWd/kgHM equal initial inventory reference for separate operation, but neither case establishes a statistically resolved advantage under the present sensitivity treatment. This work establishes a mechanism and a trade-off curve, not an operational optimum.
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Lunde, Jenny; Sandaker, Heidi & Pernegger, Heinz
(2026).
ATLAS Inner Tracker and Monolithic Sensors for future applications.
Universitetet i Oslo.
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Future collider experiments will require trackers that can handle high luminosity environments. The requirements for future trackers include high spatial and temporal resolution, low material budget, radiation hardness and low power consumption. The High-Luminosity LHC is expected to start during the summer of 2030, and is expected to deliver an integrated luminosity up to 4000 fb−1 over 10 years of operation. In preparation for the increased luminosity, ATLAS will replace its current tracker, the Inner Detector, with a new all-silicon tracker called the Inner Tracker (ITk). The work presented in this thesis addresses the development of detectors for high luminosity environments, including testing and production of modules for the ITk, as well as developments for a monolithic sensor with internal amplification.
During the time of operation, the ITk detector can undergo large temperature variations, in case of power or cooling failures. The bump bond connections of hybrid pixel detectors need to be able to withstand the thermal stress due to differences in thermal expansion coefficients between the detector materials. To ensure the robustness of the bump bonds, a thermal cycling campaign was conducted, with an overestimation of the temperature variations and number of cycles expected for the lifetime of the ITk detector. After 100 thermal cycles, none of the modules showed a significant increase in disconnected bump bonds. The study led to the qualification of the hybridization vendors, which was needed to start full scale production of planar detector modules for ITk.
To cope with high pile-up in high-luminosity environments, timing information is becoming increasingly important. The CMOS Active SenSor with Internal Amplification (CASSIA) project aims to develop a monolithic sensor with gain, to be used for time tagging or 4D tracking, where temporal resolution within a bunch crossing is added to the 3 spatial tracking dimensions. The monolithic implementation may allow for a low material budget and low power consumption, while the internal amplification gives improved timing resolution, with an aim of reaching below 100 ps timing resolution. Initial measurements and simulations of CASSIA will be presented, with a focus on gain characteristics, breakdown mechanisms and dark count rate. Different sensor design parameters, including variations in electrode and gain layer implantation, are studied to see how they affect the sensor performance.
The work presents developments of pixel detectors for high luminosity collider experiments, from conceptualization and prototyping, to testing, verification and production of detector modules.
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Holen, Gaute Arnesson; Miloch, Wojciech Jacek & Mishra, Rinku
(2026).
Plasma-object interaction in plasma environments: Numerical studies of spacecraft charging, probe accuracy and complex plasma.
Universitetet i Oslo.
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The majority of space is made up of a sea of plasma, with island of solid matter such as planets, moons, dust, spacecraft or even astronauts. Immersing any solid object in plasma results in electric charging of the object, as well as significant disturbances to the surrounding plasma. Understanding the plasma-object interaction is crucial for many situations, including reliable operation of scientific instrumentation on sounding rockets and satellites.
This thesis has developed a complementary set of numerical codes to simulate and study the plasma-object interaction. These codes were used to simulate sounding rockets, probes and daughter-payloads in the ionosphere, as well as the lunar surface and ensembles of dust particles, allowing us to study the plasma-object interaction from different perspectives.
We uncover a new trapping mechanism for ions in magnetized plasma interacting with an object using a new analytical approach and validate the daughter-payload instrumentation on the ICI-5b sounding rocket mission. Simulations of dusty plasmas show that its spatial and temporal evolution and resulting dust structure is sensitive to small charge changes.
Our studies provide new insights to the complex dynamics of objects in plasma, both for specific applications and for the fundamental understanding of objects in plasma.
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