321034 research outputs found
Sort by
X-Ray Reflectivity measurement on Strontium(II) Chloride 0.4M
No full textX-Ray Reflectivity measurement on Strontium(II) Chloride 0.4M at P08 LISAX-Ray Reflectivity measurement on Strontium(II) Chloride 0.4M at P08 LIS
Study of interfacial engineering on exchange bias effect in NiO/CoFeO heterostructures
No full textIn the present work, the magnetic properties of NiO/CoFeO (CFO) bilayers, grown via pulsed laser deposition on Si (100) substrates, have been investigated. The NiO layer thickness has been varied to explore its effect on the structural, magnetic, and electronic properties of the studied bilayer. Structural characterization of the studied compound has been analyzed using X-ray diffraction, X-ray reflectivity, atomic force microscopy, and Raman spectroscopy. An exchange bias effect has been observed in the studied bilayer, and interestingly, it varies with the thickness of the NiO layer due to the formation of an intermixed layer at the NiO/CFO interface. Furthermore, soft X-ray absorption spectroscopy (SXAS) measurement has also been carried out to study the electronic structure, and the obtained data corroborate well with its structural results. The relationship between the thickness of NiO with exchange bias can be understood through the enhanced interfacial exchange coupling between the CFO and NiO layers
Charge calibration of MALTA2, a radiation hard depleted monolithic active pixel sensor
No full textMALTA2 is a depleted monolithic active pixel sensor (DMAPS) designed for tracking at high rates and typically low detection threshold of 200e−. Threshold calibration is crucial to understanding the charge collection in the pixel. A simple procedure is developed to calibrate the threshold to unit electrons making use of a dedicated charge injection circuit and an Fe-55 source with dominant charge deposition of 1611e−. The injection voltage corresponding to the signal under exposure of Fe-55 is determined and serves as the basis for charge calibration. The charge injection circuit incorporates a capacitance with design value of Cinj=230aF. Experimentally, the average capacitance value for non-irradiated samples is found to be Cinj,exp=255±35aF and varies between sensors by 14% in terms of standard deviation. The deviation from the design value as well as among sensors motivates the need for the presented calibration procedure, which is proposed to be performed for each MALTA2 sensor and reduces the uncertainty down to 3% depending on the sensor
Microwave spectroscopy of partially and fully deuterated HCl dihydrate clusters
No full textA detailed understanding of water’s remarkable ability to solvate small molecules is a central theme in chemistry. In this work, we have identified 12 new partially and fully deuterated isotopologues of the hydrochloric acid dihydrate cluster, (H2O)2 · HCl, by chirped-pulse Fourier transform microwave spectroscopy. We also performed high-level ab initio calculations relevant to the structure and dynamics of the cluster. The observation of singly substituted isotopologues at each unique hydrogen position enables a more detailed experimental characterization of the geometry than was possible previously. In addition, an analysis of splittings in the spectrum that are caused by population of more than one vibration-tunneling level enables a detailed characterization of hydrogen bond-breaking bifurcation tunneling motions that occur in the complex. Not only do our results confirm theoretical predictions about hydrogen atoms that are permuted by the tunneling motions—they also provide experimental evidence for concerted large-amplitude motions of other atoms. Finally, an analysis of the chlorine nuclear quadrupole coupling tensor suggests that the HCl bonding character might be influenced to a small extent by isotopic substitution of atoms involved in the Cl–H⋯O hydrogen bond due to zero-point vibrational effects
First exclusive reconstruction of the B, B, and B mesons and precise measurement of their masses
No full textUsing proton-proton collision data collected by the CMS experiment at = 13 TeV in 20162018, corresponding to an integrated luminosity of 140 fb, the first full reconstruction of the three vector B meson states, B, B, and B, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be = 45.277 0.039 0.027 MeV, = 45.471 0.056 0.028 MeV, and = 49.407 0.132 0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude
Anomalous Magnetization Dynamics After Dual Optical Excitation
No full textUltrafast optical excitation is widely used to manipulate electronic and magnetic properties of materials on femtosecondtimescales. In this study, we investigate the response of copper to circularly polarized femtosecond pulses using time-resolvedmagneto-optical Kerr effect measurements. We compare the dynamics induced by single-pulse excitation with those resultingfrom a dual-pump configuration, in which two pulses arrive simultaneously from different directions. Although the individualcontributions of the two pumps are similar when applied separately, their combined effect leads to a marked change in thespin/orbital dynamics. Specifically, we observe an approximately 2.5-fold increase in the decay time of the spin/orbital imbalancesignal under dual-pump excitation. This result indicates that the joint action of two optical pulses can qualitatively alter therelaxation pathways in the system, beyond a simple additive response. The observed behavior highlights a previously unexploredregime of light-induced dynamics and suggests new strategies for controlling ultrafast processes in solids
: A Carbide Hydride Phase Incorporating
No full textReactions between carbon and lithium hydride in a mixed metal europium/lithium flux led to the synthesis of EuLi(C)H. At room temperature, the compound crystallizes in the tetragonal space group (no. 127, Z = 2; CaLi(C)H type) and undergoes a second-order structural phase transition below ∼250 K to an orthorhombic low-temperature modification (no. 55, ; Z = 4), crystallizing in a new structure type. The phase transition was monitored by using single-crystal X-ray diffraction (SCXRD) and temperature-dependent high-resolution powder diffraction data. Infrared (IR) spectroscopy and gaschromatographic analysis (GC) of the hydrolysis products confirm the existence of a first europium compound with an allylenide anion (C). Magnetic susceptibility measurements and Eu Mössbauer spectroscopy reveal the presence of divalent europium, suggesting a charge-balanced carbide hydride (Eu)(Li)(C)(H). A transition to a (soft) ferromagnetic ground state is observed below 42 K. high-pressure, high-temperature (HPHT) investigations indicate a surprisingly high stability of EuLi(C)H and yield a bulk modulus = 65 GPa. Quantum chemical calculations (DFT + ) reveal a pseudogap at the Fermi level and allow the classification as a rare-earth metal Zintl phase exhibiting both ionic and covalent bonding contributions
The mechanisms underlying the enhanced high-temperature properties of GRX-810
No full textThe demand for metal alloys that can perform at extreme temperatures above1100 °C while remaining manufacturable has sparked renewed interest inprintable oxide dispersion strengthened (ODS) alloys. Recently, NASA devel-oped an ODS alloy designed for additive manufacturing, known as GRX-810,which has demonstrated exceptional tensile and creep performance at tem-peratures of 1093 °C and higher. In the present study, tensile tests of GRX-810are conducted up to 1316 °C and creep tests are performed in both the hor-izontal and vertical orientations, relative to the build direction. Thermalcycling is executed at 1100 °C, 1200 °C, and 1300 °C in air. The oxidationbehavior of GRX-810 is compared to that of alumina forming single crystal Ni-base superalloys and chromia-forming wrought alloys such as superalloys 718and 625. High resolution atomic-scale characterization and atomistic modelingare employed to explain the exceptional high temperature propertiesobserved in GRX-810, particularly in relation to the unique, finer trigonalyttrium oxides produced during the additive manufacturing proces
Influence of strangeness on the anisotropic flow of prompt D mesons in PbPb collisions at = 5.02 TeV
No full textThe azimuthal anisotropy of prompt D mesons produced in lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is measured using data obtained with the CMS detector. The dataset corresponds to an integrated luminosity of 0.58 nb. The azimuthal anisotropy of heavy charmed mesons provides a key constraint on the interactions of charm quarks with the quark-gluon plasma (QGP) medium. These interactions include coalescence mechanisms and parton energy loss in the QGP. The anisotropy is quantified by the second- () and third-order () Fourier coefficients of the azimuthal distribution of the D mesons. The coefficient is determined in the transverse momentum range 4 40 GeV for three event centrality classes, while the coefficient is measured in the range 4 20 GeV for a single event centrality class. The results for the D mesons are compared to those previously measured for D mesons. The azimuthal anisotropy coefficients for D and D mesons are found to be consistent within the precision of this measurement, suggesting that the strangeness content of the D meson does not significantly alter its azimuthal distribution within the measured range
X-ray induced grain boundary formation and grain rotation in BiSe
No full textOptimizing grain boundary characteristics in polycrystalline materials can improve their properties. Many processing methods have been developed for grain boundary manipulation, including the use of intense radiation in certain applications. In this work, we used X-ray free electron laser pulses to irradiate single-crystalline bismuth selenide (BiSe) and observed grain boundary formation and subsequent grain rotation in response to the X-ray radiation. Our observations with simultaneous transmission X-ray microscopy and X-ray diffraction demonstrate how intense X-ray radiation can rapidly change size and texture of grains