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Development of systematic uncertainty-aware neural network trainings for binned-likelihood analyses at the LHC
No full textWe propose a neural network training method capable of accounting for the effects of systematic variations of the data model in the training process and describe its extension towards neural network multiclass classification. The procedure is evaluated on the realistic case of the measurement of Higgs boson production via gluon fusion and vector boson fusion in the decay channel at the CMS experiment. The neural network output functions are used to infer the signal strengths for inclusive production of Higgs bosons as well as for their production via gluon fusion and vector boson fusion. We observe improvements of 12 and 16% in the uncertainty in the signal strengths for gluon and vector-boson fusion, respectively, compared with a conventional neural network training based on cross-entropy
Electron thermalization and ion acceleration in XUV-produced plasma from nanoparticles in He gas environment
No full textWe use intense femtosecond extreme ultraviolet (XUV) pulses with a photon energy of 92 eV from the FLASH free electron laser to irradiate substrate-free CsCl nanoparticles surrounded by a He gas with a number density of around 10 cm. By simultaneously detecting electrons and energetic ions from the laser-irradiated micron-size target we study the acceleration mechanism of light ions at the microplasma-vacuum boundary as well as at the layer close to the nanoparticle surface. When the XUV pulse interacts with the gas alone, helium ions are accelerated to energies exceeding 100 eV. In the presence of the nanoparticle, light ions gain additional energy in the electric field around the ionized nanoparticle and their energy spectrum changes considerably. We present an electrostatic model to explain the ion acceleration mechanisms both with and without the nanoparticle and discuss the role of the gas environment in experiments
Tungsten solubility and speciation in hydrothermal solutions revealed by in situ X-ray absorption spectroscopy
No full textTungsten (W) concentrations in fluids in equilibrium with crystalline tungsten oxide are used to determine thermodynamic parameters for W solubility and W species in hydrothermal fluids. The solubility data were measured in situ at high pressures and temperatures using X-ray absorption. X-ray spectroscopic data measured in situ – with X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) – were applied to characterize the symmetry and the type of atoms of the first coordination shell of W aqueous complexes present in the fluid at given temperatures and pressures. Experiments were performed at up to 400 °C and at pressures of 40, 50 and 60 MPa. With this dataset, we were able to improve constraints for the already-suggested fluid species WO, HWO, HWO, NaWO and NaHWO. Further, we were able to introduce the HWO species that is found to be dominant in acidic fluids. No evidence was found for W species involving Cl as a ligand. The ionic W species found in the fluid are characterized by a tetrahedral complex at alkaline conditions. In neutral to acidic conditions, W complexes with distorted octahedral symmetry are formed. These complexes may be polymerized at temperatures ≤200 °C and W concentrations > 10 mol kg HO. X-ray spectroscopy as well as thermodynamic modeling suggests that polytungstate species are not relevant at equilibrium concentrations found in the solubility experiments of this study ( 10mol W kg HO in equilibrium with tungsten oxide) or at concentrations reported for natural systems. Using the thermodynamic properties of the species mentioned above, in situ data on the solubility of scheelite can be successfully described. Thermodynamic modeling shows that scheelite solubility and wolframite solubility strongly increase with increasing salinity, especially up to 1 m NaCl (m denotes molality), and vary with pH, which is consistent with earlier reports. Overall, this study provides improved thermodynamic properties for a set of W fluid species that cover a wide range of fluid compositions, which is necessary for understanding the complex processes of W enrichment and mineralization in hydrothermal systems
Measurements of Gravitational Attractions at small Accelerations
No full textGravitational interactions were studied by measuring the influence of small external field masses on a microwave resonator. It consisted of two spherical mirrors, which acted as independent pendulumsindividually suspended by strings. Two identical field masses weremoved along the axis of the resonator symmetrically and periodically betweena near and a far position. Their gravitational interaction altered the distance between the mirrors, changing the resonance frequency, which was measured and found consistent with Newton's law of gravity. The acceleration of a single mirror caused by the two field masses at the closest position varied from to
Measurement of the integrated luminosity of data samples collected during 2019-2022 by the Belle II experiment
No full textA series of data samples was collected with the Belle~II detector at the SuperKEKB collider from March 2019 to June 2022. We determine the integrated luminosities of these data samples using three distinct methodologies involving Bhabha (), digamma (), and dimuon () events. The total integrated luminosity obtained with Bhabha, digamma, and dimuon events is ({426.88} 0.03 {2.61})~fb, ({429.28} 0.03 {2.62})~fb, and ({423.99} 0.04 {3.83})~fb, where the first uncertainties are statistical and the second are systematic. The resulting total integrated luminosity obtained from the combination of the three methods is ({427.87 2.01})~fb
Adaptive observation cost control for variational quantum Eigensolvers
No full textThe objective to be minimized in the variational quantum eigensolver (VQE) has a restricted form, which allows a specialized sequential minimal optimization (SMO) that requires only a few observations in each iteration. However, the SMO iteration is still costly due to the observation noise-- one observation at a point typically requires averaging over hundreds to thousands of repeated quantum measurement shots for achieving a reasonable noise level. In this paper, we propose an adaptive cost control method, named subspace in confident region (SubsCoRe), for SMO. SubsCoRe uses the Gaussian process (GP) surrogate, and requires it to have low uncertainty over the subspace being updated, so that optimization in each iteration is performed with guaranteed accuracy. The adaptive cost control is performed by first setting the required accuracy according to the progress of the optimization, and then choosing the minimum number of measurement shots and their distribution such that the required accuracy is satisfied. We demonstrate that SubsCoRe significantly improves the efficiency of SMO, and outperforms the state-of-the-art methods
-doped tetrathia[7]helicenes: synthesis and property-change induced by “BO bond inversion”
No full textHelical distortion of polyaromatic hydrocarbons gives rise to a special class of π-conjugated systems, namely helicenes. Owing to their configurational stability and easily tunable optoelectronic properties (via heteroatom-doping), helicenes have recently come to the fore as building blocks for applications in materials science (CP-OLEDs, chiroptical switches). In this context, boron-doped helicenes are particularly promising. Herein, we report the synthesis of the new (BO)2-doped tetrathia[7]helicene 2, derived by the formal inversion of (Mes)B–O moieties in the (previously reported) isomer 1. Theoretical characterization of 2, and comparison with 1, revealed that the inversion of the BO vectors promotes the extension of the LUMO via the central thiophene–benzene–thiophene fragment (and not via the terminal thiophene rings, as in 1), resulting in a considerable lowering of the LUMO energy (ELUMO(2) = −2.22 eV vs. ELUMO(1) = −1.65 eV). Spectroscopic studies revealed that the “BO bond inversion” also contributes to the narrowing of the energy gap (Eoptg (2) = 2.90 eV vs. Eoptg (1) = 3.16 eV) and causes a significant red-shift of the absorption/emission bands (≈40 nm). Interestingly, besides low fluorescence quantum yield (ΦPL(2) = 7%), 2 shows detectable circularly polarized luminescence (glum = 0.8 × 10−3) and pronounced phosphorescence at low temperature (77 K). (P)-/(M)-enantiomers of 2 were successfully separated by CSP-UHPLC and proved to be stable (ΔG‡enant = 29.4 ± 0.1 kcal mol−1 at 353 K). Racemization studies combined with theoretical calculations confirmed that BO-doping is an extremely perturbative tool for tuning the mechanical rigidity of tetrathia[7]helicenes (ΔG‡enant (2) is 10 kcal mol−1 lower than ΔG‡enant (7TH))
Impact of carbon segregation on transition carbides and cementite precipitation during tempering of low carbon steels: Experiments and modeling
No full textTempering of low-carbon steels (less than about 0.3 wt.% C) may differ from the traditional precipitation sequence, which includes transition carbide precipitation, retained austenite decomposition and cementite precipitation. The main difference is the partial or total absence of transition carbides. In the present work, the effect of the carbon segregation on the mitigation of the precipitation of the latter is analyzed by combining multi-scale experimental investigations with a new precipitation model accounting for the carbon heterogeneities induced by the segregation. The full precipitation sequence is considered in order to study the impact of the segregation not only on the transition carbides, but also on the cementite which forms afterwards. The experimental work includes APT characterization of carbon segregation, in-situ HEXRD experiments to reveal precipitation kinetics, and TEM observations for carbide size measurements.The here-in developed precipitation mean-field and physics-based model combines two previous ones dedicated to the nucleation and growth of transition carbides and cementite and to the segregation of carbon at dislocations. It is shown that, even after water-quench, carbon atoms are already segregated on dislocations. The mitigation of transition carbide precipitation is caused by the presence of such segregations, which decrease the driving force for the transition carbide nucleation and enhance cementite precipitation. In agreement with previous experiments, the model also demonstrates that inside a martensitic microstructure, the precipitation sequence is different between the first (formed close to Ms temperature) and the last martensite (formed at room temperature) formed upon cooling, because of the difference in dislocation density, which influences the intensity of the segregation phenomenon
Neutral Sulfur Atom Formation in Decay of Deep Core Holes in
No full textDissociation upon sulfur -shell excitation or ionization of SF6 is studied by sulfur -shell emission spectroscopy using synchrotron radiation and multiconfiguration Dirac-Hartree-Fock calculations of emission energies and transition rates. The decay path involves in particular Auger emission with the ejection of one or more electrons, leading to singly or multiply charged intermediate states. Nevertheless, the results of the study show that the observed photon emission at 151–152 eV following excitation at 2485–2489 eV originates dominantly from transitions in neutral sulfur. This clearly indicates that the central atom retains its electrons in a dissociation process where all fluorine atoms detach before the S 2 decay