Review of Scientific Instruments最新文献

We report on a new versatile transportable endstation for controlled molecule (eCOMO) experiments providing a combination of molecular beam purification by electrostatic deflection and simultaneous ion and electron detection using velocity-map imaging (VMI). The b-type electrostatic deflector provides spatial dispersion of species based on their effective-dipole-moment-to-mass ratio. This enables selective investigation of molecular rotational quantum states, conformers, and molecular clusters. Furthermore, the double-sided VMI spectrometer equipped with two high-temporal-resolution event-driven Timepix3 cameras provides detection of all generated ions independently of their mass-over-charge ratio and electrons. To demonstrate the potential of this novel apparatus, we present experimental results from our investigation of carbonyl sulfide (OCS) after ionization. In particular, we provide the characterization of the molecular beam, electrostatic deflector, and electron- and ion-VMI spectrometer. The eCOMO endstation delivers a platform for ultrafast dynamics studies using a wide range of light sources from table-top lasers to free-electron-laser and synchrotron-radiation facilities. This makes it suitable for research activities spanning from atomic, molecular, and cluster physics, over energy science and chemistry, to structural biology.

Laboratory studies of rock rheology rely on purpose-built devices that can apply planetarily relevant pressures, temperatures, and non-hydrostatic stresses. Generating these pressures and stresses requires the application of large forces over small specimen areas. However, because rocks are generally polymineralic and deformation microstructures form across many length scales, it is advantageous to study relatively large (millimetric) specimens. In addition, many microstructures continue to evolve with progressive strain, so it is vital that some apparatus are able to generate enough shear strain to study these deformation phenomena. This contribution describes two new rock deformation apparatus-the Large Volume Torsion apparatus-at Washington University in St. Louis, which are capable of deforming geological specimens at high pressure and temperature (P = 3 GPa; T = 1800 K). Deformation is imposed in a torsional geometry, which enables the generation of extremely large shear strains (γ > 100) relevant to Earth's plate boundaries and convecting mantle. A large specimen (diameter up to 4.2 mm) permits detailed postmortem microstructural analysis. Apparatus design, calibration, experimental procedures, and some examples of applications are reviewed.

Here, we present a Monte Carlo toolkit for validating step range filter (SRF) spectrometer designs. Geant4 is used to transport charged particles through the SRF filters to generate synthetic SRF data that include realistic CR-39 effects. Synthetic SRF spectra generated by this method inherently account for instrument response and allow for the quantification of SRF performance before shots. The usefulness of this toolkit is demonstrated through its application to a number of problems. A new broadband SRF for the ∼10 MeV wide 3He3He proton spectrum is validated, and an analysis method for analyzing 3He3He-p SRF data that accounts for instrument response is put forth. In addition, an SRF design for the compact recoil-proton spectrometer (CRS) on the Z-machine is validated. Finally, a new calibration technique for the DD-p SRF is proposed and validated.

Angle-resolved photoemission spectroscopy (ARPES) with spatial resolution is emerging as a powerful investigative tool for the study of operational mesoscale devices and quantum materials. Here, we introduce AU-SGM4, an extreme ultraviolet beamline based at the ASTRID2 synchrotron, which is designed around an achromatic elliptical capillary optic that focuses the synchrotron light down to a lateral beam spot size of 4 μm. The beamline offers a low photon energy range of 12-150 eV, ideal for probing detailed energy- and momentum-resolved electronic structures of materials. We utilize a custom-made piezoelectric motor system with 11 degrees of freedom for precisely moving the sample and capillary optic. We demonstrate exceptional stability in beam positioning on samples across the entire available photon energy range. To showcase the capabilities of the AU-SGM4 beamline, we present simultaneous ARPES measurements and in situ gating of a graphene device and probe the nominally inaccessible microscopic-sized domains of MnBi6Te10 to obtain the energy- and momentum-dependent dispersion for each domain.

Two-dimensional (2D) quantum materials, including several analogs of graphene ("X-enes"), are of great current research interest. However, some of the potentially most exciting ones are reactive and sensitive to exposure to the atmosphere, which hampered the experimental study of their key physical properties. Here, we introduce an experimental setup that integrates sub-atomic-layer-resolved molecular beam epitaxy (MBE) synthesis, real-time low-energy electron microscopy (LEEM) and low-energy electron diffraction (LEED), and in situ six-probe electrical transport measurements. The six-probe apparatus is equipped with a dry cryocooler for reaching cryogenic temperatures, a piezoelectric XYZ nano-positioning stage for high-precision motion of the six probes, and an in situ device fabrication system for the deposition of custom-shaped gold electrodes. This design enables the six-probe system to perform both AC and DC resistance measurements on 2D quantum materials along multiple orientations within the temperature range of 5K < T < 400 K. The modules are interconnected under ultrahigh vacuum (UHV), and the samples can be synthesized by MBE, imaged by LEEM, and R(T) dependence measured without any surface contamination. We present the first experimental results that test and validate the performance of the six-probe system by transport measurements on several materials, including semiconductors and superconductors. This new instrument is proven to be a versatile platform for studying atmosphere-sensitive quantum materials.

Our previous work [X. Yu et al., Rev. Sci. Instrum. 93, 083518 (2022)] demonstrated that high field side (HFS) electron cyclotron emission (ECE) diagnostics can effectively measure electron temperature (T) information in the harmonic overlap region, where the electron distribution follows a Maxwellian. However, this requires relativistic shift corrections, which can be provided by simulation codes. Using a synthetic ECE code, we performed a statistical analysis to examine the relationship between relativistic shifts and plasma parameters, including T, electron density (n), magnetic field (B), and major radius (R0). For the first time, we proposed a scaling law for the relativistic shift in HFS ECE diagnostics, enabling direct calculation of these shifts from diagnostic data. Simulation results from both HL-3 (Huan Liu Qi-3) and ITER (International Thermonuclear Experimental Reactor) plasmas showed that this scaling law agrees well with simulated relativistic shifts (DR), even under varying pedestal heights. Furthermore, applying this scaling law, we demonstrated that it can provide results nearly identical to the preset T, even at the right-hand cutoff in high densities ITER plasmas. Finally, qualitative simulations suggest that HFS ECE can accurately localize the position of the neoclassical tearing modes (NTMs). The introduction of this scaling law represents a significant advancement in the practical application of HFS ECE diagnostics for measuring T profiles. It is expected to enhance the capabilities of ECE in high-β, high-density plasma scenarios.

This study delves into the method of qualitative analysis of terpenoid esters using near-infrared spectroscopy technology. Terpenoid esters are bioactive compounds widely used in the pharmaceutical and cosmetics industries. Near-infrared spectroscopy technology enables rapid and accurate component analysis without compromising the integrity of the sample, which is particularly important for valuable samples that need to be preserved intact or require subsequent analysis. This research combines machine learning techniques, such as K-Nearest Neighbors (K-NN) classifier, Random Forests algorithm, and Back Propagation Neural Networks (BPNN), to analyze terpenoid ester samples extracted from different concentrations of eluents, and compares and evaluates these algorithms. This study results show that in the test set, the prediction accuracy of the K-NN classifier is 96.154% and BPNN is 94.231%, and the Random Forest algorithm performs the best with a prediction accuracy of 100%. Additionally, this study utilizes the Random Forest algorithm to predict the characteristic spectra of terpenoid esters, demonstrating the effectiveness of feature spectrum extraction by ensuring a prediction accuracy of 100% while reducing the number of spectral features.

We have conducted a set of experiments on a TES (Transition-Edge Superconductor) bolometer detector array, demonstrating that a flux measurement stability better than 5 parts per million (ppm) over periods of hours to days, can be achieved with modest thermal stability requirements. This level of measurement stability is critical in enabling measurements of the atmospheric signatures of terrestrial-sized exoplanets around nearby K and M stars, including those in the star's habitable zone. The demonstration uses a simple tungsten filament light bulb as the source, a photo diode operating at 0.5 μm as a stability monitor for the light bulb, and a grating spectrometer in the 5-15 μm wavelength range.

An activity of the TRIUMF automatic beam tuning program, the Bayesian optimization for Ion Steering (BOIS) method has been developed to perform corrective centroid steering of beams at the TRIUMF ISAC facility. BOIS exclusively controls the steerers for centroid correction after the transverse optics have been set according to theory. The method is fully online, easy to deploy, and has been tested in low energy and post-accelerated beams at ISAC, achieving results comparable to human operators. scaleBOIS and boundBOIS are naïve proof-of-concept solutions to preferably select beam paths with minimal steering. Repeatable and robust automated steering reduces reliance on operator expertise and operational overhead, ensuring reliable beam delivery to the experiments and thereby supporting TRIUMF's scientific mission.

A new stick-slip piezoelectric actuator using bending deformation based on a hammer-type driving foot is proposed. Ten pieces of piezoelectric ceramic plates instead of a piezoelectric stack are clamped as a sandwich configuration to be served as an actuation unit in this work. The actuator can generate bending deformation by exciting the piezoelectric ceramic plates. Then the bending deformation is converted into the pressing and lateral displacements to press and drive the slider simultaneously due to the special structure of the hammer-type driving foot. The proposed piezoelectric actuator is introduced, and its working principle is clarified. The actuator is designed, and its main sizes are determined by means of the simulation method. A prototype is fabricated, and its output characteristics are measured. The measured results show that the proposed actuator obtained the output speed of 4.44 mm/s when the voltage and frequency are 200Vp-p and 1940 Hz. These results verify the feasibility of the proposed piezoelectric actuator based on a hammer-type driving foot in this work.