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Impact of high-pressure hydrogen charging on mechanical behavior and lattice parameters of a polycrystalline CoNiCr-based superalloy
No full textResponsive Magnetic Polymer Nanocomposites through Thermal-Induced Structural Reorganization
No full textPolymer nanocomposites (PNCs), which feature a hybrid network of soft polymers filled with nanoparticles, hold promise for application in soft robots due to their tunable physiochemical properties. Under certain environmental conditions, PNCs undergo stimuli-responsive structural rearrangement and transform the energy of the ambient environment into diverse uses, for example, repairing the injuries and reconfiguring the shapes of the materials. We develop PNCs with the ability of thermal-responsive restructuring by the stepwise assembly of functional components, including magnetite nanoparticles, silylated cellulose, and polydimethylsiloxane. We investigate the dynamic changes of the nano- and submicron structure of the magnetic PNCs upon the stimulation of heating based on a combined analytical approach: using dynamic mechanical analysis to interpret the viscoelastic properties of the PNC and in situ small-angle X-ray scattering to quantify the clustering of NPs. Based on these results, we formulate a structural model for the heating-induced evolution of the nano- to submicrometer assemblies in the magnetic PNC. Moreover, thermal-induced restructuring of magnetic PNCs leads to additional favorable functions, such as the abilities of healing, welding, reprocessing, and responses to photo and magneto stimuli. Our design provides a versatile means to develop responsive PNCs for applications in soft robots, sensors, and actuators
Optical and Upconversion Properties of AY(PO):Pr (A = Sr, Ba) Phosphors
No full textThe development of new ultraviolet (UV) phosphors is critical to unlocking the full potential of UV technologies to address global challenges related to healthcare, indoor air quality, and environmental sustainability. This work presents effective UV-C phosphors SrY(PO):Pr and BaY(PO):Pr, synthesized by the solid-state method. The luminescent properties, including both down- and upconversion, were investigated under X-ray, UV, and visible excitation. Crystallites of AY(PO) (A = Sr, Ba) activated by Pr demonstrate effective ultraviolet 5d–4f emission and weak 4f–4f emission (mainly red D → H luminescence) upon ultraviolet excitation. Selective excitation of the P level of the Pr ion in the crystallites leads to emissions in the blue, red-orange, and near-infrared regions, as well as broadband ultraviolet upconverted luminescence. The dependence of the integral intensity of Stokes and anti-Stokes emission on the concentration of the activator has been studied. The optimal concentrations of Pr ions are determined to be 1 and 1.5 mol %, and the mechanisms of concentration quenching are discussed. To elucidate the upconversion mechanism, the intensity of upconversion emission was analyzed as a function of pumping. BaY(PO):Pr shows a 6-fold increase in upconversion emission compared to YPO:Pr known from the literature, while SrY(PO):Pr exhibits a 3.5-fold increase over the same material. The spectral-luminescent and luminescence-kinetic properties of pure and Pr-doped AY(PO) (A = Sr, Ba) crystallites under excitation by X-rays up to 40 keV have been studied. The mechanism of energy transfer to Pr ions in the crystallites upon X-ray excitation is discussed. Additionally, in the temperature range of 80–730 K, the optical thermometric characteristics of AY(PO):Pr crystallites were studied using the luminescence intensity ratio between two Pr emission bands (P → H and P → H)
Measurement of inclusive and differential cross sections of single top quark production in association with a W boson in proton-proton collisions at = 13.6 TeV
No full textThe first measurement of the inclusive and normalised differential cross sections of single top quark production in association with a W boson in proton-proton collisions at a centre-of-mass energy of 13.6 TeV is presented. The data were recorded with the CMS detector at the LHC in 2022, and correspond to an integrated luminosity of 34.7 fb. The analysed events contain one muon and one electron in the final state. For the inclusive measurement, multivariate discriminants exploiting the kinematic properties of the events are used to separate the signal from the dominant top quark-antiquark production background. A cross section of pb is obtained, consistent with the predictions of the standard model. A fiducial region is defined according to the detector acceptance to perform the differential measurements. The resulting differential distributions are unfolded to particle level and show good agreement with the predictions at next-to-leading order in perturbative quantum chromodynamics.[graphic not available: see fulltext
Search for light long-lived particles decaying to displaced jets in proton–proton collisions at
No full textA search for light long-lived particles (LLPs) decaying to displaced jets is presented, using a data sample of proton–proton collisions at a center-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 34.7 fb, collected with the CMS detector at the CERN LHC in 2022. Novel trigger, reconstruction, and machine-learning techniques were developed for and employed in this search. After all selections, the observations are consistent with the background predictions. Limits are presented on the branching fraction of the Higgs boson to LLPs that subsequently decay to quark pairs or tau lepton pairs. An improvement by up to a factor of 10 is achieved over previous limits for models with LLP masses smaller than 60 GeV and proper decay lengths smaller than 1 m. The first constraints are placed on the fraternal twin Higgs (FTH) and folded supersymmetry (FSUSY) models, where the lower bounds on the top quark partner mass reach up to 350 GeV for the FTH model and 250 GeV for the FSUSY model
X-ray microscopy and talbot imaging with the matter in extreme conditions X-ray imager at LCLS
No full textPerformance Evaluation of the FASTPIX Silicon Pixel SensorTechnology Demonstrator for High-PrecisionTracking and Timing
No full textThe advancement of particle physics through current and future collider facilities pushes theboundaries of technology in HEP instrumentation. Experiments at the energy and intensityfrontier focus on high-precision measurements of Standard Model physics and searches forphysics beyond the Standard Model. The physics programs and operational conditions atfuture colliders necessitate sophisticated improvements in all detector subsystems. Detectorsin the inner layers of future experiments face stringent requirements, needing to detect singleionizing particles with small (99% are observed in test-beam for samples with processmodifications for improved charge collection.The FASTPIX results match or surpass most analog performance requirements for futurepixel detectors. A larger pixel-matrix size and the integration of full front-end and readoutfunctionality can be envisaged for future HEP applications, taking advantage of advancementsin smaller feature-size CMOS processes
Results on meson-meson scattering at large
No full textWe present results on the large scaling of meson-meson scattering amplitudes. We work in a theory with degenerate quark flavors and run lattice simulations with and pion mass MeV. We focus on three different scattering channels, two of which have the same quantum numbers as some tetraquark candidates recently found at LHCb. Finite-volume energies are extracted using a large set of operators, containing two-particle operators corresponding to two pions or two vector mesons, and local tetraquark operators. Using Lüscher's quantization condition, we constrain the infinite-volume scattering amplitudes and investigate subleading corrections to the large limit. For one of the channels, we find indications of a virtual bound state at , which may be related to one of the aforementioned exotic states
Probing gluon fluctuations in nuclei with the first energy-dependent measurement of incoherent photoproduction in ultraperipheral PbPb collisions
No full textIncoherent J/ photoproduction in heavy ion ultraperipheral collisions (UPCs), in which the photon interacts with localized, fluctuating gluonic hotspots rather than the entire nucleus, provides a unique probe of those fluctuations. This study presents the first measurement of the dependence of this photoproduction yield on the photon-nucleon center-of-mass energy (), using PbPb UPCs at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The data corresponds to an integrated luminosity of 1.52 nb, recorded by the CMS experiment. The measurement covers a wide range of 40-400 GeV, probing gluons carrying a fraction of nucleon momentum in the range between 5.9 10 and 6.5 10. The measured incoherent J/ photoproduction cross section is suppressed relative to theoretical predictions without nuclear effects. However, the ratio of incoherent to coherent photoproduction remains constant across the probed and range. Together, these results pose significant challenges to current theoretical models which include gluon saturation or nuclear shadowing effects
Evidence of the P(4459) in Upsilon(1S, 2S) inclusive decays at Belle
No full textUsing data samples of 102 million Upsilon(1S) events and 158 million Upsilon(2S) events collected by the Belle detector at the KEKB asymmetric-energy collider, we search for [udsccbar] pentaquark states decaying to Jpsi Lambda. Using the first observations of Upsilon(1S, 2S) inclusive decays to Jpsi Lambda, we find evidence of the P_ccbars(4459)0 state with a significance of 3.3 standard deviations, including statistical and systematic uncertainties. We measure the mass and width of the Pccbars(4459)0 to be (4471.7 +- 4.8 +- 0.6) MeV/c2 and (21.9 +- 13.1 +- 2.7) MeV, respectively. The branching fractions for P_ccbars(4459)0 production are measured to be B[Upsilon(1S) -> P_ccbars(4459)0/ Pbar_ccbars(4459)0 + anything] = (3.5 +- 2.0 +- 0.2)*10-6 and B[Upsilin(2S) -> P_ccbars(4459)0/ Pbar_ccbars(4459)0 +anything] = (2.9 +- 1.7 +- 0.4)*10-6. The inclusive branching fractions of Upsilon(1S, 2S) -> Jpsi Lambda/Lambdabar are measured to be B[Upsilin(1S) -> Jpsi Lambda/Lambdabar + anything] = (36.9 +- 5.3 +- 2.4)*10-6 and B[Upsilon(2S) -> Jpsi Lambda/Lambdabar + anything] = (22.3 +- 5.7 +- 3.1)*10-6. We measure the visible cross section + anything) = (90 +- 14 +- 6) fb for the continuum production at GeV. In all cases, the first uncertainties are statistical and the second are systematic