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Double Resonance is a powerful spectroscopic method that unambiguously assigns the rigorous quantum numbers of one state of a transition. However, there is often ambiguity as to the branch (ΔJ) of that transition. Spectroscopists have resolved this ambiguity by using the dependence of the double resonance intensity on the relative polarization directions of pump and probe radiation. However, published theoretical predictions for this ratio are based upon a weak (i.e., non-saturating) field approximation. This paper presents theoretical predictions for these intensity ratios for cases where the pump field is strongly saturating in the two limits of transitions dominated by homogeneous or of inhomogeneous broadening. Saturation reduces but does not eliminate the magnitude of the polarization effect (driving the intensity ratio closer to unity) even with strong pump saturation. For the case of an inhomogeneously broadened line, such as when Doppler broadened linewidth dominates over the power-broadened homogeneous line width, a large fraction of the low pump power polarization anisotropy remains. This paper reports predicted polarization ratios for both linear and circular pump and probe field polarizations. The present predictions are compared with experimental measurements on CH4 ground state → ν3 → 3ν3 transitions recently reported by de Oliveira et al.63 and these are in better agreement than with the weak field predictions. [ABSTRACT FROM AUTHOR]

In this article, we present a simulation study of the linear and nonlinear spectroscopy of dense atomic vapors. Motivated by recent experiments, we focus on double quantum spectroscopy, which directly probes dipole–dipole interactions. By explicitly including thermal velocity, we show that temperature has an important impact on the self-broadening mechanisms of the linear and nonlinear spectra. We also provide analytical expressions for the response functions in the short time limit using the two-body approximation, which shows that double quantum spectroscopy for atomic vapors directly probes the transition amplitude of the electronic excitation between two atoms. We also propose an expression for the double quantum spectrum that includes the effect of Doppler broadening, and we discuss the effect of density on the spectrum. We show that when Doppler broadening is negligible compared to self-broadening, the double quantum spectrum scales with the atomic density, while when Doppler broadening dominates, it scales as the square of the density. [ABSTRACT FROM AUTHOR]

We have applied the empirical Green's function (EGF) method to 53 pairs of earthquakes, with magnitudes ranging from M = 0.4 to M = 3.4, induced by gas production from the Groningen field in the Netherlands. For a subset of the events processed, we find that the relative source time functions obtained by the EGF deconvolution show clear indications of a horizontal component of rupture propagation. The earthquake monitoring network used has dense azimuthal coverage for nearly all events such that wavelet duration times can be picked as a function of source-station azimuth and inverted using the usual Doppler broadening model to estimate rupture propagation strike, distance, and velocity. Average slip velocities have also been estimated and found to be in agreement with typical published values. We have used synthetic data, from both a simple convolutional model of the seismogram and more sophisticated finite difference rupture simulations, to validate our data processing workflow and develop kinematic models which can explain the observed characteristics of the field data. Using a measure based on the L1-norm to discriminate results of differing quality, we find that the highest quality results show very good alignment of the rupture propagation with directions of the detailed fault map, obtained from the full-field 3D seismic data. The dip direction rupture extents were estimated from the horizontal rupture propagation distances and catalogue magnitudes showing that, for all but the largest magnitude event (the M = 3.4 event of 8th January 2018), the dip-direction extent is sufficiently small to be contained wholly within the reservoir. [ABSTRACT FROM AUTHOR]

In this work, the evolution of superparamagnetism (SPM) at room temperature is observed in the reactive magnetron sputter deposited amorphous Al-N-O alloy thin films after irradiation with oxygen ions (O−). Energy dispersive X-ray (EDX) analysis reveals the presence of notable Al-vacancy (V Al) in as-grown Al-N-O alloy thin film. X-ray photoelectron spectroscopy (XPS) confirms nitrogen trapping at V Al sites for thermodynamic stability, forming the Al(NO y) x phase. Upon the irradiation using O− at low fluence, i.e. 5 × 1013 ions/cm2, mainly V Al -O N complexes emerged. Here O N refers to nitrogen replaced by oxygen. Furthermore, an increase in oxygen fluence from 1 × 1015 to 2 × 1016 ions/cm2 yields the cross-over from V Al -O N complexes to mainly V Al , due to knocking off the trapped nitrogen atoms at V Al sites. From depth-resolved positron beam-based Doppler broadening measurements, the greater density of V Al sites is noticed in the film irradiated with the highest fluence of O− ion, i.e., 2 × 1016 ions/cm2. The correlation between the elevation of V Al sites with O− irradiation dose is in excellent agreement with the emergence of superparamagnetism (SPM) in the films. Hence, the emergence of SPM in the film after irradiation has been attributed to the creation of V Al sites, which leads to a localized magnetic moment. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation of the electrochemical characteristics and structural properties of novel nanocomposites with varying compositions of (In 2 O 3) x /(Fe 2 O 3) 1-x , where x ranges from 1 to 0. These nanocomposites were synthesized using a versatile and cost-effective co-precipitation method. The crystallographic structure and morphology of the synthesized samples were thoroughly analyzed using Powder X-ray diffraction (PXRD) and Tunneling Electron Microscopy (TEM). Advanced analytical techniques were employed including Positron Annihilation Lifetime Spectroscopy (PALS) and Coincidence Doppler Broadening Spectroscopy (CDBS) to uncover critical insights into the structural and molecular properties of these nanocomposites. PALS analysis revealed valuable insights into the pore characteristics of the nanocomposites, while CDBS identified crucial molecular interactions within the materials. Electrochemical characterization of the nanocomposites is carried out using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical-impedance-spectroscopy (EIS) measurements. The (In 2 O 3) 0.3 /(Fe 2 O 3) 0.7 nanocomposite exhibits a remarkable specific capacitance of 945 F g-1 at 1 A g-1 and exceptional rate performance, retaining 93.6% of its specific capacitance at a six-fold higher current density. Moreover, this nanocomposite electrode demonstrates outstanding cyclic stability, maintaining 92.1% of its specific capacitance even after 3000 GCD cycles at 8 A g-1. These findings suggest that the novel composition and integrated electrochemical properties of the (In 2 O 3) 0.3 /(Fe 2 O 3) 0.7 nanocomposite hold great promise for enhancing the performance of next-generation electrochemical capacitors. This research contributes valuable insights into the design and development of advanced energy storage materials with applications in various high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

Hydrothermal treatments of soda–lime silicate glass cause a remarkable improvement in the resistance to flaw formation with an increase of the critical load to ≈1 kgf. This remarkable effect is achieved even if the reaction layer between the glass and water solution is well below 1 µm. Positron Doppler broadening spectroscopy (DBS) reveals that the hydrothermal treatment causes a drop in the free volume of the glass network near the surface connected with the diffusion of molecular water whose presence was further confirmed by Fourier transformed infrared (FTIR) spectroscopy and secondary ion mass spectrometry (SIMS). Based on FTIR and SIMS, we also argue that the hydrothermal ion exchange is a double‐step process: first H+ substitutes Na+ in the network, and following molecular water permeates the system. Moreover, we show that the presence of water in the network is fundamental in stabilizing the modified glass surface leading to toughening. Once molecular water is released, the network is quickly polymerized and becomes more brittle. Hydrothermal toughening is only a partially reversible process, once water is released it is not possible to reobtain the same properties with a second treatment. Finally, it is shown that air and tin side of the float glass perform differently as a result of different water diffusion kinetics related to dissimilarities in the network density. [ABSTRACT FROM AUTHOR]

In the development of atomic physics, laser sources with Frequencies corresponding to atomic transition and high stability are essential. The Faraday laser is a special diode laser using the Faraday anomalous dispersion optical filter (FADOF) to realize frequency selection, so the output laser frequency is automatically limited to the atomic Doppler broadening. However, the frequency of a Faraday laser corresponds to the range around only one atomic hyperfine transition. Here, we realize a switchable Faraday laser with two isotopes laser frequencies corresponding to 85Rb 5 2 S 1 / 2 (F = 3) → 5 2 P 3 / 2 and 87Rb 5 2 S 1 / 2 (F = 2) → 5 2 P 3 / 2 transitions based on a single isotope 87Rb-FADOF. The laser has good robustness against the fluctuation of diode current and temperature, with wavelength fluctuating within 0.8 pm from 16 to 30 °C of diode temperature, and has a free-running linewidth of 18 kHz. We also lock the laser frequency to the two cycling transitions of 85Rb 5 2 S 1 / 2 (F = 3) → 5 2 P 3 / 2 (F ′ = 4) and 87Rb 5 2 S 1 / 2 (F = 2) → 5 2 P 3 / 2 (F ′ = 3) by the modulation transfer spectroscopy technique. The Allan deviation of the residual error signal is 3 × 10 − 14 / τ , and the frequency stability of the beat detection reaches 2.8 × 10 − 12 at 1 s integration time. This 780 nm switchable Faraday laser expands the application scenarios of Faraday lasers, which can be used in laser cooling atoms, optical frequency standards, and other quantum precision measurement fields. [ABSTRACT FROM AUTHOR]

A new x-ray imaging crystal spectrometer (XICS) has been installed, aligned, and used during experimental campaigns on the WEST tokamak. It has three interchangeable crystals for measuring the Ar XVII, Ar XVIII, and Fe XXV spectra, respectively. A patented rotating table holding the crystals is used to monitor the crystal facing the plasma remotely and without changing the position of the camera. Here, the focus is made on the Ar XVII spectrum, between 3.93 and 4.00 Å. The design of the diagnostic is presented, and a synthetic diagnostic, implemented with the Python library ToFu, is used to show the instrument's operational performance and limits. The instrument function exhibits the following two main features: a distortion for the Ar XVII spectrum, presumably due to the crystal manufacturing in two parts, and the measurement of three W spectral lines on the Ar XVI spectrum. Line of sight-integrated profiles of the electron and ion temperatures are thus extracted from the Ar XVII spectrum from two distinct spectral line ratios and from the Doppler broadening, respectively. The bremsstrahlung emission and the W line measurements are the two main limitations to compute the electron temperature. Tomographic inversions are also implemented with the library ToFu and used in order to obtain the local electron and ion temperature profiles, which are compared to other measurements from the WEST ECE (electron cyclotron emission) diagnostic. It is shown that both the XICS line-integrated and ECE Te measurements are in better agreement. Systematic differences are shown between the electron temperature profiles calculated from the two available line ratios. [ABSTRACT FROM AUTHOR]

In a vapor cell, υ is the average velocity of the moving atoms. When υ ≪ c , the in-homogeneous broadening of the atomic spectral lines is important when taking into account thermal Doppler broadening. We also discover that the narrowing mechanism for inter-atomic with different components has more influence on the Doppler line-shape. Thus, the spectral line broadening of two-level and three-level multi-mer 8 5 R b atom is not only influenced by the in-homogeneous Doppler broadening, but also affected by the Dicke narrowing effect. The fluorescence spectrum affords a good possibility for a detailed study of Dicke narrowing effect and thermal Doppler broadening effect. We analyze the influence of multi-mer 8 5 R b atomic system component on resonance fluorescence spectrum (RFS). Based on the quantum regression theorem, we develop a method and derive a general analytical expression for the two-dimensional (2D) fluorescence correlation spectrum of three-level 8 5 R b atomic system. [ABSTRACT FROM AUTHOR]

Point defects in methylammonium lead iodide (MAPbI3) are believed to be the source of its room-temperature ferromagnetic behavior. The existence of room-temperature ferromagnetism observed through the hysteresis in the M-H (magnetization vs. magnetic field) curve proves that ferromagnetism is possible even at room temperature in the tetragonal phases of MAPbI3 system. Employing positron annihilation spectroscopy, the presence of a significant amount of point defects in the ball-mill ground MAPbI3 sample has been identified. Coincidence Doppler broadening spectroscopy identifies that the point defects are mostly iodine vacancy (V˙I) in MAPbI3. Experimental data supports the theoretical prediction of iodine vacancy (V˙I)-induced ferromagnetism in the cubic phase which exists at a little higher temperature than the room-temperature tetragonal phase for MAPbI3. Moreover, the ab-initio band structure calculation shows the n-/p-type semiconducting behavior due to the vacancy formation in MAPbI3. Ferromagnetism along with semiconducting properties makes it viable for spintronics applications. [ABSTRACT FROM AUTHOR]

We present a materials analysis method to enable in-situ Doppler broadening spectroscopy (DBS) of the 511 keV annihilation line in matter during tensile tests. This technique allows the correlation between the formation of lattice defects on an atomic scale and the macroscopic physical materials properties stress and strain. By implanting a monoenergetic positron beam into samples of AlMg3 (3.3535) and AlMgSi (3.3206) the onset of plastic deformation was clearly observed in the recorded annihilation spectra during the measurement of the corresponding stress–strain curves. The changes of the DBS spectra are attributed to positron annihilation in (open-volume) defects—predominantly vacancies elastically bound to dislocation lines—formed during plastic deformation. The elastic strain (Hook's region), however, does not lead to changes in DBS spectra. [ABSTRACT FROM AUTHOR]

We conduct a comprehensive spectro-temporal analysis of repeating fast radio bursts (FRBs) utilizing nine distinct sources, the largest sample to date. Our data set includes 175 sub-bursts and 31 multicomponent bursts from 11 data sets, with centre frequencies ranging from 149 to 7144  MHz and durations spanning from 73 µs to 13 ms. Our findings are consistent with the predictions of the triggered relativistic dynamical model (TRDM) of FRB emission. We affirm the predicted quadratic relationship between sub-burst slope and central frequency, as well as a linear dependence of the sub-burst bandwidth on central frequency that is consistent with mildly relativistic Doppler broadening of narrow-band emission. Most importantly, we confirm the sub-burst slope law, a predicted inverse relationship between sub-burst slope and duration, to hold consistently across different sources. Remarkably, we also discover that the drift rates of multicomponent bursts follow the same law as the sub-burst slopes, an unexplained result that warrants further investigation. These findings not only support the TRDM as a viable framework for explaining several aspects of FRB emission, but also provide new insights into the complex spectro-temporal properties of FRBs. [ABSTRACT FROM AUTHOR]

The angular interrogation of sensitivity of the surface plasmon polariton waves (SPPs) is investigated at the interface under the effect of Doppler broadening dielectric medium and silver metal using prism geometry. A useful manipulation over the sensitivity of SPPs is obtained with Doppler broadening effect and parameters of the probe and control fields. The maximum sensitivity is investigated to 3000 deg/RIU with control field detuning, while the manimum sensitivity is reported to 300 deg/RIU with doppler width. The modified result of sensitivity of this manuscript shows potential applications in radiations guiding, photovoltaic devices, and solar cells devices. [ABSTRACT FROM AUTHOR]

Minute examination of local lattice structures in matter affected by impurity doping is of special importance for the development of functional materials. In order to obtain microscopic information on spinel ferrites, in the present work, we introduced nonmagnetic In3+ ions in Fe3O4 and probed their site selectivity and the doping effect on the local lattice structures and bulk magnetism by means of 57Fe Mössbauer spectroscopy and positron annihilation spectroscopies. The Mössbauer parameters of the area intensity and isomer shift (IS) show that In3+ ions predominantly reside in the tetrahedral A site, especially at low doping level. With increasing concentration of In ions, however, they gradually occupy the octahedral B site replacing Fe3+ ions. Along with the site information, the IS values confirmed that the introduced In ions squeeze the B-site Fe ions at their nearest neighbors. Supporting results were obtained from positron annihilation lifetime spectroscopy; positron lifetimes become shorter with increasing In concentration, signifying that the oxygen ions are pressed by the introduced In ions resulting in lowering the volume of the adjacent lattice vacancies. The results of Doppler broadening spectroscopy also support the squeezing effect; the positrons in the vacancies adjacent to In ions are more likely to annihilate with the inner shell electrons of the surrounding oxygen ions as a result of a reduction in the vacancy volume. [ABSTRACT FROM AUTHOR]

Electron beam powder bed fusion (E-PBF) is an attractive technology for the additive manufacturing of metal parts. However, process improvements require precise control of the energy transferred to the powder by the electron beam. Here, we used tunable diode laser absorption spectroscopy (TD-LAS) to measure the velocity distribution functions of titanium atoms evaporated during E-PBF. The narrow spectral ranges emitted by laser diodes allow for high-resolution absorption profiles of the evaporated atoms and thus accurate determinations of their Doppler broadening, density, and temperature during melting. The obtained vapor temperature reveals overheating at the surface of the melt pool relative to the low-pressure (0.1 Pa) boiling point of titanium, indicating that evaporation occurs under nonequilibrium conditions. We characterized the influence of the linear energy density on titanium evaporation and found it to be consistent with the saturation vapor pressure. Our characterization of the vapor properties provides reliable inputs for melt pool simulations. Furthermore, TD-LAS may be further exploited to prevent the evaporation of low-concentration alloy elements, which can induce defects in the printed part. [ABSTRACT FROM AUTHOR]

Stark broadening parameters, line widths and shifts, for 15 N VI multiplets are calculated using semiclassical perturbation theory for temperatures from 50,000 K to 2,000,000 K, and perturber density of 10 16 cm − 3 . As perturbers have been taken electrons, protons and He III ions (alpha particles), which are of interest particularly for white dwarfs. Moreover, B III, B IV, B V and B VI ions have been taken as well, due to their significance for proton-boron fusion investigations. An example of the importance of Stark broadening in comparison with thermal Doppler broadening in atmospheres of spectral class DO white dwarfs is also presented. The obtained results are of interest particularly for white dwarf atmospheres modelling and analysis and synthesis of their spectra as well as for laser driven plasma in proton-boron fusion investigations. [ABSTRACT FROM AUTHOR]

Coherent microwave-to-optical conversion is crucial for transferring quantum information generated in the microwave domain to optical frequencies, where propagation losses can be minimized. Coherent, atom-based transducers have shown rapid progress in recent years. This paper reports an experimental demonstration of coherent microwave-to-optical conversion that maps a microwave signal to a large, tunable 550(30) MHz range of optical frequencies using room-temperature 87Rb atoms. The inhomogeneous Doppler broadening of the atomic vapor advantageously supports the tunability of an input microwave channel to any optical frequency channel within the Doppler width, along with the simultaneous conversion of a multi-channel input microwave field to corresponding optical channels. In addition, we demonstrate phase-correlated amplitude control of select channels, providing an analog to a frequency domain beam splitter across five orders of magnitude in frequency. With these capabilities, neutral atomic systems may also be effective quantum processors for quantum information encoded in frequency-bin qubits. Coherent microwave-to-optical conversion is crucial for networking physically separated quantum devices. This paper demonstrates coherent conversion of microwaves to a wide, tuneable optical frequency range using room-temperature Rb atoms, supporting frequency division multiplexing and coherent frequency channel control. [ABSTRACT FROM AUTHOR]

We infer the ultrahigh energy neutrino source by using the Glashow resonance candidate event recently identified by the IceCube Observatory. For the calculation of the cross section for the Glashow resonance, we incorporate both the atomic Doppler broadening effect and initial state radiation ν ¯ e e − → W − γ , which correct the original cross section considerably. Using available experimental information, we have set a generic constraint on the ν ¯ e fraction of astrophysical neutrinos, which excludes the μ-damped pγ source around 2σ confidence level under the assumption that neutrino production is dominated by the ∆-resonance. While a weak preference has been found for the pp source, next-generation measurements will be able to distinguish between ideal pp and pγ sources with a high significance assuming an optimistic single power-law neutrino spectrum. The inclusion of multi-pion production at very high energies for the neutrino source can weaken the discrimination power. In this case additional multimessenger information is needed to distinguish between pp and pγ sources. [ABSTRACT FROM AUTHOR]

As part of efforts to develop coupled multiphysics experiments for the benchmark of modern multiphysics reactor simulators, a low-power and open-pool type of light water reactor at the Walthousen Reactor Critical Facility (RCF) was reconfigured with additional equipment, and its neutronic characteristics were fully surveyed. A water loop system was designed and installed to pass through the central region of the reactor core, making the central region overmoderated. The overmoderation would lead to a positive temperature reactivity feedback in the modified reactor configuration. This phenomenon is observed when the system temperature is between 10.69°C and 28.70°C. The inversion point of the isothermal reactivity coefficient is at 28.70°C ± 1.07°C. At this temperature, competition between the negative and positive thermal effects on reactivity compensate each other, and the isothermal reactivity coefficient becomes negative at temperatures higher than the inversion point. This paper presents the experimental determination of the isothermal reactivity and reactivity coefficient at different temperatures as well as the inversion point in the modified RCF reactor configuration. To obtain the best-quality results possible, special attention is given to the choice and adaptation of all the available methods for data postprocessing of experiment measurements. Neutron flux denoising is performed with multivariate wavelet transforms and principal component analysis. The Inverse Kinetics Method is applied to derive reactivity from the neutron flux measurements. To provide accurate and high-fidelity experiment benchmark data for modern code validation, in-depth experimental uncertainty quantification is developed. The results of the experiments show the mixed effects of system temperature on reactor reactivity due to the combined effects of Doppler broadening in the fuel, S(α,β) thermal scattering physics, and change in water density and can be used to validate previously developed cross-section interpolation models in the low-temperature range and positive isothermal reactivity coefficient conditions. [ABSTRACT FROM AUTHOR]

Organic pollutants in water remain a hazard to the ecosystem, emphasizing the ongoing concern. Therefore, this study focused on the nano-sized spinel ferrite as a photocatalyst for dye degradation and probing how ferrite microstructure influences the photo-degradation efficiency. The NiFe2O4 and ZnFe2O4 nanoparticles (NPs) were synthesized using the co-precipitation and sol–gel methods, respectively. The effects of microstructure changes of pristine and annealed (450, 600, and 800 °C) ferrites were systematically examined using the positron annihilation lifetime (PAL) and Doppler broadening (DB) techniques. Rigorous analysis, featuring X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM), confirmed the cubic spinel nanostructure for the synthesized ferrite samples as a major phase. The optical properties of the prepared ferrite NPs were studied using the UV–Vis spectroscopy. Particle size ranged from 5.0 to 34.7 nm for NiFe2O4 and from 11.8 to 50.4 nm for ZnFe2O4. UV–Vis spectra unveiled bandgap energy ranges of 3.76–4.34 and 4.31–4.60 eV for Ni and Zn ferrites, respectively. The photo-degradation efficiency of methylene blue dye catalyzed by the prepared Ni and Zn ferrite NPs was investigated. Comparing PAL and DB parameters revealed notable differences, attributed to distinct crystallinity arising from varied synthesis methods. Remarkably, the highest photo-degradation efficiency was observed in the annealed NiFe2O4 at 800 °C and pristine ZnFe2O4 samples, surpassing others. This achievement was attributed to factors such as enhanced ordered crystallinity, increased vibrational modes, optimal particle size, fitting optical properties, and favorable defect characteristics. This study's novelty lies in highlighting the pivotal role of microstructure in governing ferrite NPs photocatalyst performance. We underscore the significance of the defect reduction, regardless of its type, size or concentration, to substantially enhance the photo-degradation efficiency. [ABSTRACT FROM AUTHOR]

Fe–Cr alloys are at the forefront for high radiation tolerant materials with long-standing validated performance. Yet, the detailed mechanism behind their high radiation resistance is in question and understanding the effect of varying Cr percentage is a grand challenge limiting further improvements. Here, we applied depth-resolved positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy to study the effect of Cr alloying on the formation and evolution of atomic size clusters induced by ion-irradiation in Fe. We also used atom probe tomography to investigate the possible presence of Cr clusters or α′ phase precipitates with high Cr composition. The study reveals that the well-known resistance to radiation in Fe–Cr alloys may arise from the stabilization of vacancy clusters around Cr atoms, which act as sinks for radiation-induced defects. This implies that Cr atoms do not provide a direct sink for interstitials; rather defect complexes that consist of Cr atoms and vacancies, in turn, act as sinks for irradiation-induced vacancies and interstitials. we also find that lower amounts of Cr create smaller defect clusters that act as efficient sinks for radiation damage, but larger quantities of Cr form a defect structure that is less homogenous and larger in size, resulting in less efficient damage recombination. No evidence of α′ was found before or after irradiation, which indicates that it does not contribute to the observed radiation tolerance. [ABSTRACT FROM AUTHOR]

The equilibrium FeNi alloy prefers face centered cubic (fcc) phase whereas the formation of metastable phases through certain low‐temperature synthesis methods is obscure. FeNi alloy exhibiting nonequilibrium body centered cubic (bcc) structure beyond 5 at% Ni is obtained through chemical reduction at 453 K with noticeable lattice shrinkage. Positron lifetime analysis and Doppler broadening spectroscopy are employed to probe the correlation between defects and phase stability. The mean lifetime of the chemically synthesized alloys is larger than 300 ps, implying an average of 7‐vacancy cluster. The modified two‐state trapping model reveals defect concentration in the range of 1022 m−3$\left(10\right)^{22} \left(\text{ m}\right)^{- 3}$, on par with irradiated alloys. Significant deviation in the high‐momentum component between the bulk and chemically synthesized samples is correlated to the changes in 3d electrons. The Fe and FeNi alloy uncover significant contraction in d‐band of Fe which facilitates bcc phase stabilization above 5 at% Ni through cluster vacancy formation. [ABSTRACT FROM AUTHOR]

Alkali metal ion (Li+ and Na+)-doped CuO nanocrystallites were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), positron annihilation lifetime (PAL), and Doppler broadening annihilation radiation (DBAR) spectroscopy methods. A comparative analysis of XRD, TEM, average lifetime, and electron momentum variation is presented based on defect formation and curing. DBAR studies divulge the positron trapping sites as Cu vacancies and vacancy complex clusters in undoped CuO. The study also reveals lattice defect and migration of point defect in the doped CuO lattice. The positron lifetimes of undoped CuO show extended point defects, VCu–VO vacancy complexes, and voids. These defects are reduced to Cu interstitial (Cui) type point defects upon annealing. The lifetime confirms the VCu recovery and cluster vacancies for annealed Li- and Na-doped CuO. Higher Li concentrations showed a significant point defect of isolated oxygen vacancies as well as Li interstitials. Antisite and oxygen interstitial-type defects are prominent for all the Na concentrations. [ABSTRACT FROM AUTHOR]

The monitoring of the alpha irradiation effect on the microstructural deformation of CR39 via the variation of free volumes has been studied. CR39 samples have been irradiated with alpha particles at fluencies Φ of 2.6×108, 5.27×108, 7.91×108, 1.3×109, 1.84×109, and 3.6×109 α/cm². The samples have been investigated with positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy. The analysis of positron annihilation spectra has shown a variation of the ortho-positronium component τ3 and the parameters S and W as a function of the fluence Φ. This variation is related to a change in the size and number of free volumes, which is created via the evolution of chemical chains. From the values of τ3, the free volume radius has been estimated using the Tao–Eldrup model. Moreover, theoretical calculation of the radial dose distribution has been also performed using the Waligorski formulation to get the track core radius. After an etching of 5 min, the positron annihilation spectroscopy technique was again used to investigate the microstructural changes in etched samples subjected to alpha radiation. A clear variation of τ3, S and W parameters, and free volume radius has been noted when compared to the non-etched samples. [ABSTRACT FROM AUTHOR]

The Full Law Analysis Scattering System Hub (FLASSH) is a modern, advanced code that evaluates the thermal scattering law (TSL) along with accompanying cross sections. FLASSH features generalized methods that accommodate any material structure. Historical approximations including incoherent and cubic approximations have been removed. Instead, the latest release of FLASSH features advanced physics options including distinct effect corrections (one-phonon contributions) and noncubic formulations. Noncubic elastic and inelastic contributions are necessary to accurately evaluate one-phonon contributions. Both noncubic and one-phonon calculations require high-density sampling of the various scattering directions. Optimization and parallelization of these routines were therefore necessary to produce results in a reasonable computational time frame. With these notable improvements to the generalized TSL, FLASSH 1.0 can meet benchmark requirements by permitting realistic comparisons with experiments for both TSLs and the resulting integrated cross sections. Within FLASSH, these high-fidelity TSLs can be applied also to the resonance region to evaluate accurate, material structure-dependent Doppler broadening that captures the observed experimental behavior. Additional features including a graphical user interface (GUI), plotting diagnostics, and formatted output options including ACE files allow users to complete a TSL evaluation with minimal input and maximum flexibility. The user GUI creates input files for FLASSH, reducing user error and also providing built-in error checks. Autofill options and suggested input values help make TSL evaluation accessible to novice users. The FLASSH code is compiled to run on both Windows and Linux platforms with automatic parallelization. [ABSTRACT FROM AUTHOR]

The Doppler coefficient represents the primary source of passive and instantaneous negative reactivity feedback to limit peak power excursion during reactivity-initiated accidents as well as a nonnegligible negative reactivity source that changes between cold zero-power and hot zero-power conditions. Furthermore, the mechanism behind the Doppler coefficient may also contribute to an increase in the buildup of Pu under normal operating conditions. As such, its treatment is critical in the design and evaluation of the safety and control of nuclear systems. This paper provides a brief overview of the physical source of the Doppler effect through resonance broadening from first principles as well as an exploration of some recent developments in the treatment of elastic scattering in the Monte Carlo codes Tripoli4® and MCNP. This exploration results in a detailed look at the effect different elastic scattering kernels have on the radiative capture, fission, and elastic scattering rates as they directly tie into the calculation of the Doppler coefficient via the six-factor formula. Also provided is some insight into the propagation of the a priori uncertainty of 238U resonance parameters. This work is performed pursuant to the development of a new experimental program to measure the Doppler coefficient in a zero-power reactor both more accurately and to higher temperatures (1500°C to 2000°C) than has been done in the past at the MINERVE facility at Cadarache. [ABSTRACT FROM AUTHOR]

Data on microporosity (micropore size distribution) in the range from several angstroms to several nanometers, obtained by measuring the positron annihilation lifetime (PALS method) and by measuring CO2 sorption (low-temperature gas sorption, LTGS) are collated for a number of polymers with amorphous (polyetherimides, PEI) and semicrystalline (polyphenylene oxides, PPO) structures. The microporosity estimates based on the positron annihilation and CO2 sorption data are compared with published data obtained both experimentally and by the group contribution method for the permeability of these materials. The discrepancies found and their possible causes are discussed. [ABSTRACT FROM AUTHOR]

The pressure in an underwater discharge channel is the main parameter that influences all its applications. In this study, we investigate a relatively large gap with a plane-to-plane electrode geometry that uses the assistance of an injected gas bubble for breakdown. The delay in the application of high voltage following the injection of a gas bubble from a grounded electrode determines the initial dimensions of the bubble. We examined three types of discharge: (a) a large bubble with easy triggering, (b) a medium bubble, and (c) a small bubble with difficult triggering. The main diagnostic tool is H α line broadening. It is shown that (i) Doppler broadening plays no role; (ii) at pressure broadening, the resonance and van der Waals broadenings must be considered; (iii) the impact approximation is not applicable, and hence the quasi-static high-pressure (namely 'nearest neighbour') approximation must be used; and (iv) the Stark broadening plays the dominant role. Because a mixture of two gases (evaporated water vapour and nitrogen from bubble injection) is present in the discharge channel, simple thermodynamic considerations were applied to estimate the ratio of the contributions of resonance and van der Waals broadening. The larger the bubble, the smaller the pressure detected in the discharge channel. This is in agreement with the measurements of the pressure wave amplitude at a certain distance from the discharge channel using a piezoelectric pressure probe. [ABSTRACT FROM AUTHOR]

The dynamics and spectral characteristics of supernova ejecta reveal details of the supernova energetics, explosive nucleosynthesis, and evolution of the progenitor. However, in practice, this important diagnostic information is only derived from CCD-resolution X-ray spectra of shock-heated material. If the spectra were to be observed at higher resolution, then important clues to the explosion energetics would be obvious through measurements of bulk Doppler motions and turbulence in the ejecta. Likewise, the unshocked ejecta in supernovae and young remnants are responsible for obscuring the emission from ejecta on the back side of the remnant. In light of these important effects, we present line-of-sight spectral maps of core-collapse supernova remnant models. We explore the bulk Doppler broadening of spectral lines, including line-of-sight effects. We also explore the time-dependent absorption from both shocked and unshocked ejecta. Finally, we discuss how future X-ray missions such as XRISM and Athena will be able to resolve these effects in nearby and extragalactic supernovae and their remnants. [ABSTRACT FROM AUTHOR]

The current model for the polarized brightness (pB) spectrum has a decades-long history of progressively incorporating its dependence on electron density N e , temperature T e , and flow velocity in the radial direction V e . The pB N e spectrum follows the exact shape of the photosphere spectrum, which is not smooth, which is expected from the thermal Doppler broadening of the photosphere spectrum due to the high coronal T e ; the pB N e T e spectrum is smooth, but the free coronal electrons remain static and unaffected by solar wind, and the pB N e T e V e spectrum is red-shifted by electrons seeing a red-shifted photosphere spectrum as they flow away from the Sun as solar wind, which takes a radial direction above 2.5 R ⊙ from Sun center. In this article, we review the progress of the above three model pB spectra in describing the observations and highlight the differences, first by comparing the three model pB spectra against wavelength using a model for N e and constant values for T e and V e , and second by generating three model 2D pB maps by integrating over a selected wavelength region in the three model pB spectra along lines of sight passing through the 14 July 2000 ("Bastille Day") coronal mass ejection (CME) model, which contains 3D information on N e , T e , and V e . In this regard, the COronal Diagnostic EXperiment (CODEX) on the International Space Station (ISS) in 2024 will measure N e , T e , and V e by matching the measured pB with modeled pB N e T e V e in selected wavelength regions using multiple filters. [ABSTRACT FROM AUTHOR]

This work endeavours to bring out the role of initial microstructural features and alloying additions in the irradiation response of a material. Three Zr-based binary alloys, namely Zr-0.17 wt.% O, Zr-0.33 wt.% Sn and Zr-2.5 wt.% Nb, with starting microstructures exemplifying annealing, hot-extrusion and cold-pilgering operations, respectively, were selected. The alloys were irradiated at room temperature using 315 keV energy Ar9+ heavy ion. Depth-dependent microstructural evolution of the alloys upon irradiation was assessed through positron annihilation Doppler broadening spectroscopy and grazing incidence X-ray diffraction, while nanoindentation probed the mechanical behaviour. Irradiation responses of the alloys garnered in terms of S-parameter, coherently scattering domain size, microstrain, dislocation density and hardness were compared. The observed differences were rationalized on the basis of (i) starting microstructural attributes of the alloys, which posed as sinks to the irradiation-induced point defects, and (ii) impact of alloying additions on diffusion and annihilation of these defects. [ABSTRACT FROM AUTHOR]

Barium di-silicide (BaSi2) is a very promising absorber material for high-efficiency thin-film solar cells, due to its suitable bandgap, high light absorption coefficient, and long minority-carrier lifetime. In this study, we compare the nanostructure, layer composition, and point defects of BaSi2 thin films deposited by Radio Frequency (RF) sputtering, Thermal Evaporation (TE), and Molecular Beam Epitaxy (MBE), using Doppler Broadening Positron Annihilation Spectroscopy (DB-PAS) depth profiling, Raman spectroscopy, and x-ray diffraction. Our DB-PAS study on thermally annealed RF-sputter deposited and on TE-deposited BaSi2 layers, in a comparison with high quality BaSi2 films produced by MBE, points to the presence of vacancy-oxygen complexes and Si or Ba mono-vacancies, respectively, in the (poly)crystalline BaSi2 films. The degree of near-surface oxidation increases, going from MBE and TE to the industrially applicable RF-sputtered deposition synthesis. The use of a-Si capping layers on the thermally annealed RF-sputtered BaSi2 films leads to a clear reduction in sub-surface oxidation and improves the quality of the BaSi2 films, as judged from DB-PAS. [ABSTRACT FROM AUTHOR]

A comparative analysis of two popular spectroscopy techniques is conducted in a coaxial cylindrical capacitively coupled discharge designed for the plasma processing of superconducting radio frequency (SRF) cavities. The density of the metastable and resonant levels in Ar is measured in both Ar and Ar/Cl 2 discharges to properly characterize the unique discharge system and aid in the development of a cavity etching routine. The first method, deemed the "branching fraction method," utilizes the sensitivity of photon reabsorption of radiative decay to measure the lower state (metastable and resonant) densities by taking ratios of spectral lines with a common upper level. This method has been gaining popularity as it does not require any a priori knowledge about the electron energy distribution. The second method is a tunable diode laser absorption spectroscopy technique that measures the thermal Doppler broadening of spectral lines, from which the neutral gas temperature and lower state density of the transition can be evaluated. The two methods were conducted in tandem, while external parameters that were empirically determined to be important to the etching mechanism of SRF cavities are varied. Relationships between the excited state densities and the external parameters are presented for both spectroscopy methods and conclusions about the effects of these parameters on the discharge are stated when appropriate. [ABSTRACT FROM AUTHOR]

A three-step photoionization has been theoretically studied for the laser isotope separation of 223Ra through the following photoionization scheme. 7 s 2 1 S 0 0.0 cm - 1 → 714.3185 nm 7 s 7 p 3 P 1 o 13999.3569 cm - 1 → 784.0270 nm 7 s 8 s 3 S 1 26754.02 cm - 1 → 558 / 581 nm Autoionization State → Ra + The effect of bandwidth, peak power density of the excitation and ionization lasers, Doppler broadening of the atomic ensemble, number density of the atoms, and charge exchange collisions on the laser isotope separation process has been studied. The optimum system parameters for the separation of 223Ra through this photoionization scheme have been derived. The effect of unknown parameters on the degree of enrichment has also been discussed. It has been theoretically shown that it is possible to produce 223Ra isotope with 98.5% radio-isotopic purity at a rate of 0.74 μg/h corresponding to the production rate of 435 patient doses per hour. This is the first ever study on the laser isotope separation of Radium isotopes. [ABSTRACT FROM AUTHOR]

The non‐stationary clutter phenomenon and the severe range ambiguity make space‐based early warning radar as an intricate model of received ground and sea clutter. The received clutter is severely broadened in Doppler dimension, and the degrees of freedom (DOFs) of the received clutter is severely increased. Because the DOFs of the system is always lower than the theoretical DOFs of the received clutter, the adaptive processing capability of the system is insufficient and the performance of clutter suppression is seriously degraded. A multi‐domain cascaded adaptive processing method is proposed in this study. The proposed method takes full advantage of the digital antenna array to suppress a portion of the clutter energy by introducing the transmit pulse coding domain, and the remaining influential clutter energy is suppressed by introducing the elevation‐dimensional receive channel domain. Finally, the clutter after the two‐dimensional (2D) pre‐processed is suppressed by the 2D adaptive processing in the azimuthal receive beam‐receive Doppler domain. This method pre‐processes the clutter data by extending the processing dimension to meet the freedom requirements of the adaptive signal processing, and the capability of clutter suppression is significantly improved. Simulation examples show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

We report on measurements of rotational and vibrational temperature, velocity, and concentrations of nitric oxide (NO) in freestream flows at the T5 reflected shock tunnel at California Instistute of Technology. Quantities were measured at 50 kHz by tunable diode laser absorption spectroscopy using five lasers simultaneously to sample 27 quantum state-specific transitions. To isolate core flow measurements from the shear flow surrounding it, optical flow-cutter arms were designed. Two sets of arms with differing optical path lengths were used to assess freestream spatial uniformity. This study consists of nine total experiments ("shots") spanning four nominal conditions with reservoir enthalpy 8-21 MJ/kg and flow velocity 3.5-5.5 km/s. Freestream measurements generally imply thermal equilibrium of the rotational and vibrational temperatures except at lower-enthalpy conditions. We compare temperature measurements with predictions from five species air simulations and find reasonable agreement at lower-enthalpy conditions but underprediction of NO concentrations. At higher-enthalpy conditions, we observed transitory agreement in temperature but overprediction of NO concentrations. Measured and simulated velocity generally agree well across all conditions. Carbon monoxide, water, and potassium were also detected in the T5 flow, and their concentrations are reported where relevant. [ABSTRACT FROM AUTHOR]

We develop a nonlinear theory of propagation of a monochromatic light wave in a gas of two-level atoms under the condition of inhomogeneous Doppler lineshape broadening, while considering a self-consistent solution of the Maxwell–Bloch equations in the mean-field approximation using a single atom density matrix formalism. Our approach shows a significant deformation of the Doppler resonant lineshape (shift, asymmetry), which depends on the atomic density. These effects are a consequence of only the free motion of atoms in a gas and is not associated with interatomic interaction. In particular, the frequency shift of the field-linear contribution to the transmission signal is more than an order of magnitude greater than the shift due to the interatomic dipole–dipole interaction, and the first nonlinear correction has an even stronger deformation, which exceeds the effect of the interatomic interaction by three orders of magnitude. The found effects caused by the free motion of atoms require a significant revision of the existing picture of spectroscopic effects, which depend on the atomic density in a gas. [ABSTRACT FROM AUTHOR]

In nuclear reactors, tracking the loss and production of neutrons is crucial for the safe operation of such devices. In this regard, the microscopic cross section with the Doppler broadening function is a way to represent the thermal agitation movement in a reactor core. This function usually considers the Maxwell–Boltzmann statistics for the velocity distribution. However, this distribution cannot be applied on every occasion, i.e., in conditions outside the thermal equilibrium. In order to overcome this potential limitation, Kaniadakis entropy has been used over the last seven years to generate generalised nuclear data. This short review article summarises what has been conducted so far and what has to be conducted yet. [ABSTRACT FROM AUTHOR]

This tutorial introduces the theoretical and experimental basics of electromagnetically induced transparency (EIT) in thermal alkali vapors. We first give a brief phenomenological description of EIT in simple three-level systems of stationary atoms and derive analytical expressions for optical absorption and dispersion under EIT conditions. Then we focus on how the thermal motion of atoms affects various parameters of the EIT system. Specifically, we analyze the Doppler broadening of optical transitions, ballistic versus diffusive atomic motion in a limited-volume interaction region, and collisional depopulation and decoherence. Finally, we discuss the common trade-offs important for optimizing an EIT experiment and give a brief 'walk-through' of a typical EIT experimental setup. We conclude with a brief overview of current and potential EIT applications. [ABSTRACT FROM AUTHOR]

A novel spectroscopy diagnostic for measuring internal magnetic fields in high temperature magnetized plasmas has been developed. It involves spectrally resolving the Balmer-α (656 nm) neutral beam radiation split by the motional Stark effect with a spatial heterodyne spectrometer (SHS). The unique combination of high optical throughput (3.7 mm2sr) and spectral resolution (δλ ∼ 0.1 nm) allows these measurements to be made with time resolution ≪1 ms. The high throughput is effectively utilized by incorporating a novel geometric Doppler broadening compensation technique in the spectrometer. The technique significantly reduces the spectral resolution penalty inherent to using large area, high-throughput optics while still collecting the large photon flux provided by such optics. In this work, fluxes of order 1010 s−1 support the measurement of deviations of < 5 mT (ΔλStark ∼ 10−4 nm) in the local magnetic field with 50 µs time resolution. Example high time resolution measurements of the pedestal magnetic field throughout the ELM cycle of a DIII-D tokamak plasma are presented. Local magnetic field measurements give access to the dynamics of the edge current density, which is essential to understanding stability limits, edge localized mode generation and suppression, and predicting performance of H-mode tokamaks. [ABSTRACT FROM AUTHOR]

• Oxide film was formed after 350 °C/10 MPa water corrosion. • An obvious increment of S value was observed in irradiated & corroded specimens. • Irradiation promoted the production and accumulation of corrosion-related defects. • Corrosion-related defects induced the formation of cracks on the dense oxide films. To understand irradiation accelerated the corrosion behavior further, the early-stage aqueous corrosion-related behavior was investigated in heavy ion irradiated P92 ferritic/martensitic alloy by multiple characterization techniques. The oxide film was formed at 350 °C/10 MPa water for 80 h. The surface morphology of irradiated specimen was different from that of unirradiated specimen. Many grains were fused together in irradiated specimen. Doppler broadening spectroscopy of slow positron beam shows that the existence of irradiation defects could accelerate the production and accumulation of corrosion-related defects in the deeper region of the oxide film. [ABSTRACT FROM AUTHOR]

2S 0921−630 is an eclipsing low-mass X-ray binary (LMXB) with an orbital period of ∼9 d. Past X-ray observations have revealed that 2S 0921−630 has an extended accretion disk corona (ADC), from which most of the X-rays from the system are emitted. We report the result of our Suzaku archival data analysis of 2S 0921−630. The average X-ray spectrum is reproduced with a blackbody emission (kT bb ∼ 0.3 keV) Comptonized by optically thick gas ("Compton cloud"; optical depth τ ∼ 21) with a temperature of ∼2 keV, combined with 13 emission lines. We find that most of the emission lines correspond to highly ionized atoms: O, Ne, Mg, Si, S, Ar, and Fe. A Kα emission line and an absorption edge of semi-neutral iron (Fe  textsci– textscxvii) are also detected. The semi-neutral iron Kα line is significantly broad, with a width of 0.11 ± 0.02 keV in sigma, which corresponds to the Doppler broadening by the Kepler motion at a radius of ∼109 cm. We suggest that the observed semi-neutral iron line originates at the inner part of the accretion disk in the immediate outside of the Compton cloud, i.e., the Compton cloud may have a radius of ∼109 cm. [ABSTRACT FROM AUTHOR]

In this work, we studied the evolution of vacancy-like defects and the formation of brittle precipitates in a reduced-activation V−Cr−Mn medium-entropy alloy. The evolution of local electronic circumstances around Cr and Mn enrichments, the vacancy defects, and the CrMn3 precipitates were characterized by using scanning electron microscopy with energy-dispersive spectroscopy, X-ray diffraction, and positron annihilation spectroscopy. The microstructure measurements showed that the Mn and Cr enrichments in the as-cast sample significantly evolved with temperature, i.e., from 400 °C, the Cr/Mn-segregated regions gradually dissolved into the matrix and then disappeared, and from 900 °C to 1000 °C, they existed as CrMn3 precipitates. The crystallite size of the phase corresponding to CrMn3 precipitates was about 29.4 nm at 900 °C and 43.7 nm at 1000 °C. The positron annihilation lifetime results demonstrated that the vacancies mediated the migration of Cr and Mn, and Cr and Mn segregation finally led to the formation of CrMn3 precipitates. The coincidence Doppler broadening results showed that the characteristic peak moved to the low-momentum direction, due to an increase in the size of the vacancy defects at the interface and the formation of CrMn3 precipitates. [ABSTRACT FROM AUTHOR]

The characterization of polymeric nanocomposite thin films of polyvinyl alcohol (PVA) doped with various concentrations of copper nanoparticles (Cu–NPs) by the aid of casting technique is synthesis and detailed. The PVA/Cu nanocomposite thin films are containing wt.% = 0%, 0.04%, 0.08%, and 0.1% of (Cu–NPs). The X-ray diffraction (XRD) exhibits the semi-crystalline behavior of all polymeric films. The Fourier transform Infrared (FTIR) results show some remarkable changes in the spectral characteristics of the thin films after adding (Cu–NPs) to (PVA) solution. Scanning electron microscopy (SEM) shows partial homogeneity between the polymeric matrix and the nano filler. The Ultraviolet–Visible (UV–Vis) spectroscopy is used to measure the optical parameters. Tauc and Urbach models are used to predict optical bandgap energy (Eg), Urbach energy (Eu), and optoelectronic properties of PVA/ Cu–NPs nanocomposites. The dielectric characteristics of the nanocomposite thin films show an improvement when the nano-filler is added to the polymeric matrix. The changes in microstructure of the PVA/Cu–NPs composite thin films are analyzed by the positron annihilation lifetime (PAL) and the Doppler broadening (DB) techniques. [ABSTRACT FROM AUTHOR]

Atom gravimeters use locked lasers to manipulate atoms to achieve high-precision gravity measurements. Frequency modulation spectroscopy (FMS) is an accurate method of optical heterodyne spectroscopy, capable of the sensitive and rapid frequency locking of the laser. Because of the effective absorption coefficient, Doppler broadening and susceptibility depend on temperature, and the signal-to-noise ratio (SNR) of the spectroscopy could be affected by temperature. We present a detailed study of the influence of the temperature on FMS in atom gravimeters, and the experimental results show that the SNR of the spectroscopy is dependent on temperature. In this paper, the frequency of the reference laser is locked by tracking the set point of the fringe slope of FMS. The influence of the frequency-locking noise of the reference laser on the sensitivity of the atom gravimeter is investigated by changing the temperature of the Rb cell without extra operations. The method presented here could be useful for improving the sensitivity of quantum sensors that require laser spectroscopic techniques. [ABSTRACT FROM AUTHOR]

A double-chord ion Doppler spectroscopy (IDS) system was developed to measure the ion temperature and flow velocity of field-reversed configuration (FRC) plasmas in the FRC amplification via a translation-collisional merging (FAT-CM) device. Adopting a Czerny–Turner mount monochromator and 16-channel photomultiplier tube array, the developed IDS system achieves high wavelength resolution and fast time response. In addition, two vertically aligned optical paths share the optical system up to the monochromator and then branch just before the detector, successfully reducing crosstalk to <1%. The Doppler broadening was measured at two measurement points in the FAT-CM device, simultaneously, and ion temperatures of ∼50 eV were measured. Toroidal spin-up from 7 to 15 km/s and a steady flow velocity of ∼10 km/s were estimated from the Doppler shift obtained by the developed system. The observation of the toroidal flow velocity and the spatial profile of the ion temperature of the FRC plasma in the FAT-CM device were realized. These spectroscopic diagnostic's double chord capabilities will aid in understanding and improving the FRC plasmas. [ABSTRACT FROM AUTHOR]