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Corrigendum to “Structural pathways for ultrafast melting of optically excited thin polycrystalline Palladium films” [Acta Materialia, 276 (2024) 120043]
No full textSearch for a standard model-like Higgs boson in the mass range between 70 and 110 GeV in the diphoton final state in proton-proton collisions at = 13 TeV
No full textThe results of a search for a standard model-like Higgs boson decaying into two photons in the mass range between 70 and 110 GeV are presented. The analysis uses the data set collected by the CMS experiment in proton-proton collisions at s=13TeV corresponding to integrated luminosities of 36.3fb−1, 41.5fb−1 and 54.4fb−1 during the 2016, 2017, and 2018 LHC running periods, respectively. No significant excess over the background expectation is observed and 95% confidence level upper limits are set on the product of the cross section and branching fraction for decays of an additional Higgs boson into two photons. The maximum deviation with respect to the background is seen for a mass hypothesis of 95.4 GeV with a local (global) significance of 2.9 (1.3) standard deviations. The observed upper limit ranges from 15 to 73fb
Activating metastability engineering via control of initial microstructure in C-added CoCrFeNiMo medium-entropy alloy: in situ X-ray diffraction study
No full textDeformation-induced martensitic transformation (DIMT) from face-centered cubic to body-centered cubic or body-centered tetragonal martensite in metastable ferrous medium-entropy alloys (FeMEAs) can be effectively tuned by modifying initial microstructures to achieve the desired mechanical response. For example, partial recrystallization can promote a faster rate of DIMT by providing numerous nucleation sites for the martensite embryos, such as profuse shear bands and nanotwins. Precipitation-driven changes in matrix concentrations can also influence the phase stability and the DIMT kinetics. In this work, two Co18.5Cr12Fe55Ni9Mo3.5C2 (at%) FeMEA samples with different fractions of recrystallized regions and precipitate volume fractions were fabricated, and the difference in their DIMT behaviors and work hardening responses was investigated with in situ high energy X-ray diffraction analysis during tensile testing. The sample with a higher fraction of non-recrystallized regions and carbide precipitates showed low FCC phase stability mediated by the profuse nucleation sites in non-recrystallized regions and precipitation-driven metastability, and rapid DIMT to α′ martensite from the beginning of plastic deformation. Meanwhile, the other sample showed a delay in DIMT until the final stage of deformation. The lattice strain evolution demonstrated dynamic stress partitioning onto the newly born α′ martensite. Furthermore, the phase stress calculation showed that the stress partitioning creates a meaningful contribution to the enhancement of the work hardening and flow stress of the sample with the faster DIMT kinetics, validating our strategy to regulate DIMT via initial microstructure in search of improved mechanical performances
Long‐Term Stability and Oxidation of Ferroelectric AlScN Devices: An Operando Hard X‐ray Photoelectron Spectroscopy Study
No full textAluminum scandium nitride (Al1−xScxN) is a promising material for ferroelectric devices due to its large remanent polarization, scalability, and compatibility with semiconductor technology. By doping AlN with Sc, the bonds in the polar AlN structure are weakened, which enables ferroelectric switching below the dielectric breakdown field. However, one disadvantage of Sc doping is that it increases the material's tendency toward oxidation. Herein, the oxidation process of tungsten-capped and uncapped Al0.83Sc0.17N thin films is investigated by hard X-ray photoelectron spectroscopy (HAXPES). The samples is exposed to air for either 2 weeks or 6 months. HAXPES spectra indicate the replacement of nitrogen by oxygen and the tendency of oxygen to favor oxidation with Sc rather than Al. The appearance of an N2 spectral feature thus can be directly related to the oxidation process. An oxidation model that mimics these spectroscopic results of the element-specific oxidation processes within Al1−xScxN is presented. Finally, in operando HAXPES data of uncapped and capped AlScN-capacitor stacks are interpreted using the proposed model
Noninvasive cavity-based charge diagnostic forplasma accelerators
No full textThe charge of an electron bunch is one of the most important parameters in accelerator physics. Several techniques to measure the electron bunch charge exist. However, many conventional charge diagnostics face serious drawbacks when applied to plasma accelerators. For example, integrating current transformers (ICTs or toroids) have shown to be sensitive to the electromagnetic pulses (EMP) originating from the plasma, whereas scintillating screens are sensitive to background radiation such as betatron radiation or bremsstrahlung and only allow for a destructive measurement of the bunch charge. We show measurements of a noninvasive, cavity-based charge diagnostic (so-called DaMon), which demonstrate its high sensitivity, high dynamic range and resistance towards plasma EMP. The measurements are compared to both an ICT and an absolutely calibrated scintillator screen
Observations of Turbulence and Particle Transport at Interplanetary Shocks: Transition of Transport Regimes
No full textThe transport of energetic particles is intimately related to the properties of plasma turbulence, a ubiquitous dynamic process that transfers energy across a broad range of spatial and temporal scales. However, the mechanisms governing the interactions between plasma turbulence and energetic particles are not completely understood. Here we present comprehensive observations from the upstream region of a quasi-perpendicular interplanetary (IP) shock on 2004 January 22, using data from four Cluster spacecraft to investigate the interplay between turbulence dynamics and energetic particle transport. Our observations reveal a transition in energetic proton fluxes from exponential to power-law decay with increasing distance from the IP shock. This result provides possible observational evidence of a shift in transport behavior from normal diffusion () to superdiffusion (, with ), where is particle displacement over the timescale . This transition correlates with an increase in the time ratio from to , where is the proton isotropization time, and is the turbulence correlation time. Additionally, the frequency-wavenumber distributions of magnetic energy in the power-law decay zone indicate that energetic particles excite linear Alfv\'en-like harmonic waves through gyroresonance, thereby modulating the original turbulence structure. These findings provide valuable insights for future studies on the propagation and acceleration of energetic particles in turbulent astrophysical and space plasma systems
Numerical model of broadband pulse amplification in cryogenic Yb:YLF regenerative amplifiers
No full textWe present a chromatic numerical model of gain dynamics based on rate equations in cryogenic 3+ amplifiers, experimentally verified with broadband amplification in Yb:YLF. The model includes saturation effects, spectral evolution, and gain element temperature
Modified Conjugate Quantum Natural Gradient
No full textThe efficient optimization of variational quantum algorithms (VQAs) is critical for their successful application in quantum computing. The Quantum Natural Gradient (QNG) method, which leverages the geometry of quantum state space, has demonstrated improved convergence compared to standard gradient descent [Quantum 4, 269 (2020)]. In this work, we introduce the Modified Conjugate Quantum Natural Gradient (CQNG), an optimization algorithm that integrates QNG with principles from the nonlinear conjugate gradient method. Unlike QNG, which employs a fixed learning rate, CQNG dynamically adjusts hyperparameters at each step, enhancing both efficiency and flexibility. Numerical simulations show that CQNG achieves faster convergence than QNG across various optimization scenarios, even when strict conjugacy conditions are not always satisfied -- hence the term ``Modified Conjugate.'' These results highlight CQNG as a promising optimization technique for improving the performance of VQAs
Influence of the Galactic Halo on the UHECR Multipoles
No full textWe examine the effects of a giant magnetized halo around the Galaxy on the angular distribution of the arriving ultra-high energy cosmic rays (UHECR) observed at Earth. We investigate three injection scenarios for UHECRs, and track them through isotropic turbulent magnetic fields of varying strengths in the Galactic halo. We calculate the resultant dipole and quadrupole amplitudes for the arriving UHECRs detected by an observer in the Galactic plane region. We find that, regardless of the injection scenario considered, when the scattering length of the particles is comparable to the size of the halo, the UHECRs skymap resembles a dipole. However, as the scattering length is increased, the dipolar moment always increases, and the quadrupolar moment increases rapidly for two of the three cases considered. Additionally, the quadrupole amplitude is highlighted to be a key discriminator in discerning the origin of the observed dipole. We conclude that, to understand the origin of the UHECR dipole, one has to measure the strength of the quadrupole amplitude as well
Estimation of Quantum Fisher Information via Stein's Identity in Variational Quantum Algorithms
No full textThe Quantum Fisher Information Matrix (QFIM) plays a crucial role in quantum optimization algorithms such as Variational Quantum Imaginary Time Evolution and Quantum Natural Gradient Descent. However, computing the full QFIM incurs a quadratic computational cost of O(d^2) with respect to the number of parameters d, limiting its scalability for high-dimensional quantum systems. To address this limitation, stochastic methods such as the Simultaneous Perturbation Stochastic Approximation (SPSA) have been employed to reduce computational complexity to a constant (Quantum 5, 567 (2021)). In this work, we propose an alternative estimation framework based on Stein's identity that also achieves constant computational complexity. Furthermore, our method reduces the quantum resources required for QFIM estimation compared to the SPSA approach. We provide numerical examples using the transverse-field Ising model and the lattice Schwinger model to demonstrate the feasibility of applying our method to realistic quantum systems