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Spectro-Microscopy of Individual Pt–Rh Core–Shell Nanoparticles during Competing Oxidation and Alloying
No full textThe surface chemical composition of supported single Pt-Rh core-shell nanoparticles was studied to understand the Rh behavior in oxidizing and reducing gas environments using spectro-microscopy with high spatial resolution. We combined in situ X-ray photoemission electron microscopy with ex situ scanning electron-, atomic force- and scanning Auger-microscopy to distinguish Rh oxidation-reduction, dewetting-sintering and alloying-segregation during the course of the experiment. A more than 20% higher Rh 3d oxide to metal photoemission intensity ratio for the Rh layer on top of the Pt-core was found as compared to the bare strontium titanate (STO) oxide catalyst support in close vicinity, where Rh/RhO nanoparticles are forming. At elevated temperatures, Rh diffuses into the Pt particle, and this alloying at the Pt metal surface competes with the Rh oxidation, whereas the Rh/RhO nanoparticles on the STO support are observed to sinter under identical oxidizing and temperature environments. A nanoparticle facet dependent analysis of selected Pt-core nanoparticles suggests that Rh oxidation is most advanced on a small nanoparticle with a low coordination top facet that we indexed by electron back scatter diffraction, demonstrating the strength of our correlative approach
Transferability and interpretability of vibrational normalizing-flow coordinates
No full textThe choice of vibrational coordinates is crucial for the accuracy, efficiency, and interpretability of molecular vibrational dynamics and spectra calculations. We explore the recently proposed normalizing-flow vibrational coordinates, which are learned molecule-specific coordinate transformations optimized for a given basis set. Much like how spherical coordinates naturally simplify the hydrogen atom by embedding physical insight into the coordinate system, normalizing-flow coordinates offload complexity from the basis functions into the coordinate transformation itself. This shift not only improves basis-set convergence, but also enhances interpretability of vibrational motions. We provide an analysis of the utility, interpretation and associated constraints of normalizing-flow vibrational coordinates. Moreover, we demonstrate that these coordinates can be generalized across different isotopologues, and even structurally related molecules, achieved with minimal fine-tuning of selected output parameters
A Linear Collider Vision for the Future of Particle Physics
No full textIn this paper we review the physics opportunities at linear colliders with a special focus on high centre-of-mass energies and beam polarisation, take a fresh look at the various accelerator technologies available or under development and, for the first time, discuss how a facility first equipped with a technology mature today could be upgraded with technologies of tomorrow to reach much higher energies and/or luminosities. In addition, we will discuss detectors and alternative collider modes, as well as opportunities for beyond-collider experiments and R&D facilities as part of a linear collider facility (LCF). The material of this paper will support all plans for linear colliders and additional opportunities they offer, independently of technology choice or proposed site, as well as R&D for advanced accelerator technologies. This joint perspective on the physics goals, early technologies and upgrade strategies has been developed by the LCVision team based on an initial discussion at LCWS2024 in Tokyo and a follow-up at the LCVision Community Event at CERN in January 2025. It heavily builds on decades of achievements of the global linear collider community, in particular in the context of CLIC and ILC
Photo- and Hadrodisintegration constraints on massive relics decaying into neutrinos
No full textWe perform a detailed study of the cosmological constraints on the decay of a relic particle into neutrinos, , in particular those arising from the observed light-element abundances in the early Universe. We focus on the late-time disintegration of the light elements previously synthesised during BBN. Several processes are relevant, including final-state radiation associated with the decay, as well as subsequent interactions of the injected neutrinos with the thermal background neutrinos or between themselves. All processes generically contribute to the production of electromagnetic and often also hadronic material and may therefore induce late-time photodisintegration and hadrodisintegration reactions, i.e.~the destruction of light elements that have previously been formed during BBN. Here, we examine this scenario with a Monte-Carlo inspired probabilistic approach rather than Boltzmann techniques, taking into account all of these different reactions as well as their interplay. We find the resulting constraints to be very significant, covering a broad range of previously unexplored masses and lifetimes of the relic source particle
Bracketing the soliton-halo relation of ultralight dark matter
No full textIn theories of ultralight dark matter, solitons form in the inner regions of galactic halos. The observational implications of these depend on the soliton mass. Various relations between the mass of the soliton and properties of the halo have been proposed. We analyze the implications of these relations, and test them with a suite of numerical simulations. The relation of Schive et al. 2014 is equivalent to where and are the energy and mass of the soliton (halo). If the halo is approximately virialized, this relation is parametrically similar to the evaporation/growth threshold of Chan et al. 2022, and it thus gives a rough lower bound on the soliton mass. A different relation has been proposed by Mocz et al. 2017, which is equivalent to , so is an upper bound on the soliton mass provided the halo energy can be estimated reliably. Our simulations provide evidence for this picture, and are in broad consistency with the literature, in particular after accounting for ambiguities in the definition of at finite volume
Simulation and measurement of Black Body Radiation background in a Transition Edge Sensor
No full textThe Any Light Particle Search~II (ALPS~II) experiment at DESY, Hamburg, is a Light-Shining-through-a-Wall (LSW) experiment aiming to probe the existence of axions and axion-like particles (ALPs), which are candidates for dark matter. Data collection in ALPS~II is underway utilizing a heterodyne-based detection scheme. A complementary run for confirmation or as an alternative method is planned using single photon detection, requiring a sensor capable of measuring low-energy photons (, ) with high efficiency (higher than ) and a low background rate (below ). To meet these requirements, we are investigating a tungsten Transition Edge Sensor (TES) provided by NIST, which operates in its superconducting transition region at millikelvin temperatures. This sensor exploits the drastic change in resistance caused by the absorption of a single photon.We find that the background observed in the setup with a fiber-coupled TES is consistent with Black Body Radiation (BBR) as the primary background contributor.A framework was developed to simulate BBR propagation to the TES under realistic conditions.The framework not only allows the exploration of background reduction strategies, such as improving the TES energy resolution, but also reproduces, within uncertainties, the spectral distribution of the observed background. These simulations have been validated with experimental data, confirming the modeled background distribution and thatthe improved energy resolutionreduces the background rate in the signal region by one order of magnitude to a rate in the order of .However, this rate must be reduced to meet the ALPS II requirements
OSCARS: Taking science research to the next level
No full textOpen Science Clusters’ Action for Research and Society (OSCARS) is a EU-funded project that will bring your research data to new audiences and target new use-cases. FAIR (Findable, Accessible, Interoperable and Reusable) data allows research data to be used in new and novel ways, with increased citations acknowledging the original researchers and facilities that provided that data.OSCARS covers a broad range of science activities, including Humanities and Social Sciences, Life Sciences, Environmental Sciences, Astronomy, and Neutron and Photon Science. This allows adoption and tailoring of existing software and services to match photon science needs.OSCARS builds on the EOSC (European Open-Science Cloud) science clusters outcomes to support open science, by enhancing communication between the science clusters (WP1), improving the outcomes of the science clusters software and services (WP2), connecting this activity with other EOSC funded activities (WP3) and providing direct funding for open science projects (WP4).WP1 will establish a specific domain-orientated community-based competence centre for the science clusters facilities. These competence centres will focus on the community's specific achievements and skills, addressing their scientific community’s needs. This will encourage and strengthen intra-cluster collaboration, the sharing of best practices, software, services and strategy development.WP2 takes a catalogue of existing services, data hubs and analysis platforms of varying maturity and will identify how they might be composed, possibly when enhanced, to provide broader support for scientific investigation. This might involve services and software from different science clusters, breaking down barriers that prevent cross-domain research and allowing new research. OSCARS will enhance specific tools to show the benefits to researchers.WP3 will build connections between OSCARS and other EOSC projects, task forces and related work. This ensures OSCARS benefits from existing work, aligns OSCARS activity with effort elsewhere, and increases the uptake of OSCARS outcomes. WP3 will also establish testing methodology to drive up the quality of the project’s outcomes.WP4 oversees a funding programme, split into two rounds. Each call will be open for two months and will accept a wide range of proposals that target open science and the FAIR data environment. At the time of SRI 2024, the first call will have closed; however, the second call will open in November 2024. Successful proposals will be funded for 1–2 years, with a budget of 100–250 k€.Here, we will present the strategy within OSCARS and provide the anticipated impact within the photon science community, as core members of the Photon and Neutron Open Science Cloud (PaNOSC)
Consolidation of Services in the Photon and Neutron Open Science Cluster
No full textThe EU project OSCARS (Open Science Clusters’ Action for Research and Society) brings your research data to new audiences and targets new use-cases in a broad range of scientific clusters including Photon and Neutron Sciences (PaN). As recommended by a new White Paper (submitted to IUCrJ) from the user organisations, ESUO and ENSA, adherence to the FAIR principles (Findable, Accessible, Interoperable, Reusable) facilitates the use of research data in novel ways, with increased citations acknowledging original researchers and facilities that provided that data. Further, increased (meta)data and software findability and accessibility promotes a better use of resources by reducing the duplication of experiments.We are currently engaged in the Consolidation task by cataloguing existing services and data sources, aiming to highlight common approaches between the clusters and to identify “composable” services. For the PaN Open Science Cluster (PaNOSC) this will create such a portfolio from scratch starting with link collections from the most relevant Research Infrastructures (RIs) of PaNOSC, e.g. LEAPS, LENS, and European Research Infrastructure Consortia (ERICs). The representatives of the different RIs within the PaNOSC Competence Center (also established within OSCARS) contributed significantly by adding new resources and also by completing information on already listed resources (e.g. TRL, licences). Currently, the portfolio contains more than 500 resources.The portfolio provides the basis to identify services required for a specific task within a specific research scenario. We are currently collecting PaNOSC-typical scenarios that can be simplified by composing and slightly adapting the involved services. One or two scenarios will be realised as demonstrators within the project. The services and data sources could be onboarded to the thematic PaN EOSC node, which is being proposed as candidate node of the EOSC Federation
Refining Two-Loop Corrections to Trilinear Higgs Couplings
No full textThe precise determination of the Higgs self-couplings is an essential task for understanding electroweak symmetry breaking and probing physics beyond the Standard Model (SM). The calculation of two-loop corrections is important to provide a critical test of the perturbative stability, especially in the case of large one-loop corrections that can occur in scenarios with extended scalar sectors. Morever, they need to be taken into account for the future perspective of precisely measuring the Higgs self-couplings. In this talk, we will present our work on the leading two-loop corrections to the trilinear Higgs couplings in the two-Higgs-doublet model (THDM) and other models beyond the SM. We focus in particular on the couplings hhh, hhH , which are the most important for di-Higgs production at the (HL-)LHC. In our calculation we adress the renormalization of the alignment limit in the Higgs basis. We give some insights into the technical details of the calculation and discuss the phenomenological impact of our results
Algebraic Structures and Open Problems in AdS/CFT Integrability
No full textSince the early 2000s, the discovery of integrable sectors in the AdS/CFT correspondence has established a deep connection between string theory, quantum groups, and exactly solvable models. In this framework, the R-matrix in specific representations encodes the scattering properties of interacting strings through quantum group symmetries. While integrability has led to major successes in computing the energy spectrum, a complete algebraic formulation in terms of a universal R-matrix is still needed to fully understand scattering amplitudes. In this talk, I will review the known structures and highlight key open problems, along with some recent ideas and potential directions that merit further investigation