Opacity Measurements Research Articles

Testing the optical components for the National Ignition Facility time-resolved soft x-ray opacity spectrometer (OpSpecTR).

Opacity measurements are being carried out at the Z-facility at Sandia National Laboratories and at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. The current soft x-ray Opacity Spectrometer (OpSpec) used on the NIF uses two elliptically bent crystals in time-integrated mode on either an image plate or a film. Plans are under way to expand these opacity measurements into a mode of time-resolved detection, called OpSpecTR. Previously, considerations for the available hCMOS detector size and photometrics led to a crystal geometry redesign and the use of a grazing angle x-ray mirror. The mirror acts as a low-pass x-ray energy filter, reducing the contribution of higher energy x rays. The first tests of the mirror and the crystal for OpSpecTR are presented here. The size of the mirror reflection and the reflectivity is tested using a Manson x-ray source. The mirror coupled with the new elliptical crystal shape demonstrates OpSpecTR's spectral coverage. The results from the x-ray optics performance testing are shown along with the intended design.

An Imaging and Spectroscopic Exploration of the Dusty Compact Obscured Nucleus Galaxy Zw 049.057* *Based in part on observations obtained with the Southern African Large Telescope (SALT).

Zw 049.057 is a moderate-mass, dusty, early-type galaxy that hosts a powerful compact obscured nucleus (CON, L FIR,CON ≥ 1011 L ⊙). The resolution of the Hubble Space Telescope enabled measurements of the stellar light distribution and characterization of dust features. Zw 049.057 is inclined with a prominent three-zone disk; the R ≈ 1 kpc star-forming inner dusty disk contains molecular gas, a main disk with less dust and an older stellar population, and a newly detected outer stellar region at R > 6 kpc with circular isophotes. Previously unknown polar dust lanes are signatures of a past minor merger that could have warped the outer disk to near face-on. Dust transmission measurements provide lower limit gas mass estimates for dust features. An extended region with moderate optical depth and M ≥ 2 × 108 M ⊙ obscures the central 2 kpc. Optical spectra show strong interstellar Na D absorption with a constant velocity across the main disk, likely arising in this extraplanar medium. Opacity measurements of the two linear dust features, pillars, give a total mass of ≥106 M ⊙, flow rates of ≥2 M ⊙ yr−1, and few Myr flow times. Dust pillars are associated with the CON and are visible signs of its role in driving large-scale feedback. Our assessments of feedback processes suggest gas recycling sustains the CON. However, radiation pressure driven mass loss and efficient star formation must be avoided for the active galactic nucleus to retain sufficient gas over its lifespan to produce substantial mass growth of the central black hole.

Development of improved higher-order correction for the NIF opacity spectrometer.

X-ray opacity measurements on the National Ignition Facility (NIF) are in the process of reproducing earlier measurements from the Sandia Z Facility, in particular for oxygen and iron plasmas. These measurements have the potential to revise our understanding of the "solar problem" and of the hot degenerate Q class white dwarf structure by probing plasma conditions near the base of their convection zones. Accurate opacity measurements using soft x-ray Bragg crystal spectrometers require correction for higher-order diffraction effects. Extending prior work in this area [Dutra etal., Review of Scientific Instruments 93, 113527 (2022)], we have developed a new method to remove higher-order spectral components from NIF opacity spectrometer data. By modeling absorption and backlighting continuum spectra and subtracting the second- and third-order components from the measured data, we are able to perform this correction while avoiding imprinting first-order model line features onto the data.

Reusable, Green, Portable Ionogels Based on Terpyridine-Imidazole Salt for Visual Monitoring of Pork Spoilage.

Ionogels have emerged as a promising approach because they combine the advantageous properties of ionic liquids and gels. Herein, a novel gelator bearing terpyridine and imidazolium salt units was designed and synthesized, which assembled into ionogels in three ionic liquids by a heating-cooling procedure. The properties of ionogels were characterized by FT-IR, UV-vis spectroscopy, POM, XRD, and rheology, and resonance light scattering and opacity measurements were conducted to investigate the gelation kinetics. Furthermore, the ionogels incorporating pH-sensitive dyes (BTB and MR) were exploited as colorimetric sensor to monitor total volatile basic nitrogen (TVB-N) of meat at -4 °C, which can easily and reliably estimate the quality of meat by naked eye recognition, and the results demonstrated a positive correlation between the color variation and TVB-N levels. Notably, the hydrophobic ionogel indicators are more suitable for potential application at high humidity thanks to their antiswelling advantage, which could prevent the inaccurate information produced by hydrogel indicators. In addition, the ionogels could be reused up to three times as colorimetric indicators, suggesting potential applications and competitiveness. Our research sheds new light on the novel application of ionogels in the food industry.

Measurement of 2p-3d absorption in a hot molybdenum plasma

We present measurements of the 2p-3d transition opacity of a hot molybdenum–scandium sample with nearly half-vacant molybdenum M-shell configurations. A plastic-tamped molybdenum–scandium foil sample is radiatively heated to high temperature in a compact D-shaped gold Hohlraum driven by ∼30 kJ laser energy at the SG-100 kJ laser facility. X rays transmitted through the molybdenum and scandium plasmas are diffracted by crystals and finally recorded by image plates. The electron temperatures in the sample in particular spatial and temporal zones are determined by the K-shell absorption of the scandium plasma. A combination of the IRAD3D view factor code and the MULTI hydrodynamic code is used to simulate the spatial distribution and temporal behavior of the sample temperature and density. The inferred temperature in the molybdenum plasma reaches a average of 138 ± 11 eV. A detailed configuration-accounting calculation of the n = 2–3 transition absorption of the molybdenum plasma is compared with experimental measurements and quite good agreement is found. The present measurements provide an opportunity to test opacity models for complicated M-shell configurations.

Bank opacity, systemic risk and financial stability

This paper examines the impact of bank opacity on European financial stability. Based on a panel dataset of listed European banks covering the period 2002–2018, I find that bank opacity has a significant influence on the institution-specific contribution to the ∆Conditional Value at Risk and Marginal Expected Shortfall. The enforcement mechanism and the policies introduced by accounting standard setters and regulators for the risk disclosure of banks have a positive impact on the reduction of systemic risk. Both the risk reporting in accordance with IFRS 7 and the measures introduced by the Basel Committee in the form of the Basel Pillar 3 regulation led to an increase in transparency and thus an improvement in financial market stability. As an independent enforcement mechanism, the country-specific strength of the external auditing profession plays a significant role in fostering stability. The results are robust, by using both alternative opacity measures and instrumental-variable estimations (2SLS) to control for potential endogeneity.

Quantitative analysis of the Martian atmospheric dust cycle: Transported mass, surface dust lifting and sedimentation rates

The atmospheric dust cycle on Mars plays a dominant role in the planetary radiative balance, atmospheric photochemistry escape, and redistribution of materials on the surface. Although this planetary dust cycle has been extensively modelled and characterized with both orbital and in situ observations, to date little is known about the total mass of dust that is circulated, the actual dust lifting and settling rates, and the main dust sources and sinks. Using orbital global and seasonal measurements of atmospheric dust opacity, a data reduction methodology that can describe the annual dust redistribution cycle on a planetary scale with 95% accuracy is presented. The method was applied to the 9.3 μm infrared observations of the Thermal Emission Spectrometer (TES) aboard the Mars Global Surveyor (MGS) during two full Martian Years (MY) 25 and 26, and partly MY 24 and MY 27, disregarding the global dust storm that occurred in MY 25. By comparison with terrestrial observations, a mass-to-extinction conversion factor of 1.9 ± 0.3 g m−2 is proposed, assuming a dust density of 2.6 g cm−3. The analysis shows an estimation of 400 1012 g of dust transported globally in the atmosphere for a typical Mars year, which is comparable to the minimum total annual mass of dust transported on Earth. The methodology proposed here is based on remote sensing and cannot disentangle completely local surface lifting and sedimentation rates from dust advection. However, this analysis provides upper bounds which can be compared with in-situ observations. The analysis of the dust sedimentation cycle suggests that the annual cycle might produce a dust layer of about 50–100 μm on the surface of some particular zones, as Valle Marineris or Meridiani Planum. This estimation agrees with in-situ observations of rovers on Mars. The potential dust sources are mainly located from latitudes of 20°S to 60°S. Our results find the 70% of the sources previously identified by the existing planetary circulation models. This kind of large-scale analysis can be applied to other remote sensing observations to refine these calculations and study the annual and geographical variability of the dust-mass transport on Mars.

High-precision room temperature Fe opacity measurements at 1000-2000eV photon energies

Prior measurements of room temperature (cold) Fe opacity have errors as high as ±10 % and a spread in values that exceeds the uncertainties. These data, along with current cold opacity databases, were used for comparison with experimental solar Fe opacity. The solar Fe opacity is expected to be lower than cold Fe opacity in the ∼1500–2000 eV photon energy range. However, results from this comparison contradicted this assumption and prompted an investigation of the precision and accuracy of cold Fe opacity measurements. Cold Fe opacity is determined here with high precision using transmission measurements of Fe foils at three characteristic line energies in the soft X-ray range (1000–2000 eV). The present opacities are determined with ≲1 % overall uncertainties. This is achieved through precise measurements of transmission and areal density which are related to opacity by the Beer-Lambert Law. Transmission is measured with overall individual uncertainties of ≲1 % and is obtained through simultaneous measurements of attenuated and unattenuated spectra using an X-ray source and a Bragg crystal spectrometer. The required areal density is indepen-dently measured using two different techniques: Rutherford Backscattering Spectroscopy and a recently-developed technique using calibrated cold absorption in the 3–17 keV range. The final areal density used in the opacity determination is an average between both methods. The measured opacity at 1188 eV is in agreement with current opacity databases but is higher by around 5–10 % at the highest photon energy (1924 eV) and lower by around 2–4 % at the lowest photon energy (1012 eV). A caveat is that opacity accuracy is linearly dependent on the areal density. We performed the first direct comparison between the two areal density methods which revealed a 7–11 % discrepancy. If one of the methods is proven correct in future studies, it may impact the opacity accuracy reported here since we use the average of the two methods. This result affects the solar Fe opacity measurements as they also rely on the accuracy of these areal density measurement techniques.

Probing Dust and Water in Martian Atmosphere with Far-Infrared Frequency Spacecraft Occultation

Airborne dust plays an active role in determining the thermal structure and chemical composition of the present-day atmosphere of Mars and possibly the planet’s climate evolution over time through radiative–convective and cloud microphysics processes. Thus, accurate measurements of the distribution and variability of dust are required. Observations from the Mars Global Surveyor/Thermal Emission Spectrometer Mars Mars Reconnaissance Orbiter/Mars Climate Sounder and Mars Express/Fourier Transform Spectrometer and the Curiosity Rover have limited capability to measure dust. We show that spacecraft occultation of the Martian atmosphere at far-infrared frequencies between 1 and 10 THz can provide the needed global and temporal data on atmospheric dust by providing co-located measurements of temperature and dust opacity from the top of the atmosphere all the way down to the surface. In addition, spacecraft occultation by a small-satellite constellation could provide global measurements of the development of dust storms.

Experimental study on fuel consumption and smoke opacity of defective coffee-bean-based biodiesel fuel engines

This experimental study aims to analyse the performance of sorted coffee beans-based biodiesel. This study is carried out in three main stages; (a) the preparation process of coffee beans raw material, (b) the biodiesel formation process, and (c) biodiesel performance analysis. In manufacturing process, the coffee bean powder is added with two chemical treatments sequentially; extraction-distillation and esterification/transesterification. Parameters of analysis in this study are the characteristics of the biodiesel and the performance of the biodiesel-diesel mixture in terms of fuel consumption efficiency and engine smoke opacity. Measurements of Engine Running Time (ERT) and smoke opacity were carried out on a single-piston diesel engine. There were five biodiesel-diesel mixture specimens; B0, B5, B10, B15, and B20 (20% biodiesel fraction). The experimental results show that mixing biodiesel with diesel fuel provides two main advantages; extending engine running time which means fuel consumption efficiency, and lowering the smoke opacity level. Therefore, it is more environmentally friendly. The efficiency of fuel consumption and smoke opacity depends on the biodiesel fraction in the fuel mixture. The results and methodology of this research are expected to be an additional reference in the development of biodiesel as an alternative fuel.

Societal trust and bank opacity

PurposeThis paper aims to examine the relationship between societal trust and bank asset opacity using an international sample of banks.Design/methodology/approachThe authors use an international data set of banks and panel regressions. For robustness purposes, the authors use multiple measures of both societal trust and bank opacity as well as two-stage least squares regressions to address endogeneity concerns.FindingsThe authors find that societal trust is negatively associated with the opacity of bank portfolios.Practical implicationsResults of this study inform regulators on the importance of trust for the banking sector and support policies towards enhancing trust in banks. Also, a sustained environment of high levels of trust in banks can prevent the introduction of extensive prudential regulations that policymakers often use to establish trust, as well as lower the additional resources required when trust levels are low.Originality/valueTo the best of the authors’ knowledge, this is the first study that examines this relationship. The literature provides only limited evidence and not for the banking sector, for which opacity is of outmost importance.

Laboratory measurements of the 15–46 cm wavelength opacity of water vapor under temperature conditions characteristic of the deep atmosphere of Jupiter

The Juno Microwave Radiometer (MWR) has six channels ranging from 600 MHz (50 cm) to 22 GHz (1.3 cm) and has the ability to peer deep into the Jovian atmosphere. Previous laboratory measurements determined the microwave opacity of ammonia and water vapor at pressures and temperatures corresponding to regions sensed by MWR channels 2–6 which function between 1.25 GHz and 22 GHz (Hanley et al., 2009, Devaraj et al., 2014, Bellotti et al., 2016/2017, Karpowicz and Steffes, 2011a, b). The discovery of significant ammonia and water variability at pressures >30 bars (Bolton et al., 2021) indicated the need to provide laboratory opacity measurements at the higher temperatures characteristic of the conditions at higher pressures. Of specific interest is the region sensed by MWR's lowest frequency which senses regions where the physical temperatures reach well above 750 K. Laboratory measurements of the microwave opacity of water vapor at 760 K have been conducted in the frequency range from 649 to 2001 MHz (wavelengths from 15 to 46 cm). These are the first such laboratory measurements known to be conducted at such high temperatures and long wavelengths, and can resolve the inconsistency between the water vapor self-continuum opacity components of the existing models. The results from these laboratory measurements provide better insight into the effects of water vapor on Jupiter's 50 cm wavelength emission and will provide more reliable retrievals of atmospheric composition in the deep atmosphere of Jupiter.Print.

The world price of macro opacity: Through the lens of nighttime satellites

This paper proposes a macro opacity measure from the perspective of macroeconomic data accuracy through the lens of nighttime satellites. Macro opacity varies with countries’ governance and culture, while higher macro opacity often relates to higher cost of capital.

Initial characterization of a dynamic hohlraum radiation source tailored for high-temperature opacity measurements at an 8-MA facility

This paper reports some important properties of a dynamic hohlraum radiation source intended to study the high-temperature opacity of medium-Z atoms. The time-resolved axial radiation power in two x-ray diodes gives the time-evolution of an equivalent black-body temperature that peaks at ∼260 eV at stagnation. Time-gated framing pinhole images show that the source comprises an intense high-temperature core that lasts for ∼2 ns preceded by a 10-ns-long lower-temperature implosion phase that emits mostly softer x rays. Combining pinhole images with soft x-ray power gives a time-resolved brightness radiation temperature that reaches 130 eV. Thus, the lower-temperature source could ionize an opacity sample, then the intense high-temperature radiation pulse could measure its opacity. Likewise, the time-integrated spectrum measured with a spherically bent crystal spectrometer is compatible with multiple blackbodies with different temperatures, from 176 to 185 eV. These characterizations suggest that this dynamic hohlraum can be used for high-temperature opacity measurements.

MWCNT nanocomposite films prepared using different ratios of PVC/PCL: Combined FT-IR/DFT, thermal and shape memory properties

Multi-wall carbon nanotube (MWCNT) mechanically strengthens the polymer and increases heat transfer within polymers as it increases its electrical properties. In this study, composites were produced by doping with poly ɛ-caprolactone (PCL) / poly vinyl chloride (PVC) blend prepared at different ratios, with a fixed MWCNTs ratio of 0.1%. By doing this, it is aimed to examine the effect of polymers, which are blend components, for the MWCNT polymer blend composite. It has been observed that all of the composites have shape-memory effects. When the thermal properties of the MWCNT blend composite were examined, it was observed that the melting temperature increased with increasing PCL ratio, in addition, two-step mass loss occurred in all composites. From the opacity measurements, it was seen that the transparency increased as the PVC ratio increased. Additionally, it was determined that the peaks overlapped when the density functional theory (DFT) and experimentally derived Fourier Transform Infrared spectroscopy (FTIR) spectra were compared.

Single-shot measurements of pulse-front tilt in intense ps laser pulses and its effect on accelerated electron and ion beam characteristics (invited).

We report recent single-shot spatiotemporal measurements of laser pulses, including pulse-front tilt (PFT) and spatial chirp, taken at the Compact Multipulse Terawatt laser at the Jupiter Laser Facility in Livermore, CA. STRIPED FISH, a device that measures the complete 3D electric field of fs to ps laser pulses on a single shot, was adapted to near infrared for these measurements. We present the design of the instrument used for these experiments, the on-shot measurements of systematic high-order PFT, and shot-to-shot variations in the measurements of spatiotemporal couplings. Finally, we simulate the effect of PFT in target normal sheath acceleration experiments. These simulations showed that pulse front tilt can steer hot electrons, shape the distribution of the accelerating sheath field, and increase the variability of cutoff energy in the resulting proton spectra. While these effects may be detrimental to experimental accuracy if the pulse front tilt is left unmeasured, hot electron steering shows promise for precision manipulation of the particle source for a range of applications, including irradiation of secondary targets for opacity measurements, radiography, or neutron generation.

Ocular surface disorders affect quality of life in patients with autoimmune blistering skin diseases: a cross-sectional study

BackgroundAutoimmune blistering skin diseases (AIBD) are a group of rare chronic autoimmune diseases which are associated with ocular surface diseases especially dry eye disease. This study is designed to investigate the relationship between ocular surface disorders and quality of life among patients with autoimmune blistering skin diseases.MethodsTwenty-four AIBD patients (18 pemphigus and 7 pemphigoid) and twenty-five non-AIBD controls were included. Ocular surface disease index (OSDI), ocular surface evaluation, including slit-lamp examination, Schirmer I test, tear break-up time, corneal fluorescein staining, lid-parallel conjunctival folds, meibomian gland evaluation, presence of symblepharon and corneal opacity were assessed. Life quality was evaluated by multiple questionnaires, including Medical Outcomes Study 36-Item Short Form Questionnaire (SF-36), Hospital Anxiety and Depression Scale (HADS), Pittsburgh Sleep Quality Index (PSQI) and Health Assessment Questionnaire-Disability Index (HAQ-DI). Ocular surface tests and quality of life were compared between AIBD patients and non-AIBD controls. In the AIBD patients, the associations between ocular surface parameters and quality of life were also evaluated.Results92% of AIBD patients and 87.5% of age- and sex-matched non-AIBD controls were diagnosed with dry eye in this study. Compared with non-AIBD controls, AIBD patients reported lower SF-36 scores (P < 0.05) and severer OSDI, Schirmer I test, tear break-up time, corneal fluorescein staining, presence of symblepharon and corneal opacity measures (P < 0.05). OSDI, Schirmer I test were correlated with SF-36 composite scores or scores on the SF-36 subscales.ConclusionsAIBD patients experience reduced quality of life and more severe ocular surface disorders including dry eye, symblepharon and corneal opacity. Early treatments of dry eye and collaborations among multidisciplinary physicians are necessary in patients with AIBD.

Measurement of the K-band atmospheric opacity using the sky-dips method with a horn antenna

Measurement of the K-band atmospheric opacity using the sky-dips method with a horn antenna

2nd and 3rd order spectral energy corrections with penumbral de-blurring methodology for opacity platform used on the National Ignition Facility.

The Opacity Spectrometer (OpSpec) used in the National Ignition Facility's opacity experiments measures x-ray spectra from 0.9 to 2.1keV from the different experimental regions: the backlight source, emission source, and the absorption region with the transmission calculated from these regions. The OpSpec designs have gone through several iterations to help improve the signal-to-noise ratio, remove alternate crystal plane reflections, and improve spectral resolution, which helps to increase the validity of the opacity measurements. However, the source spans well outside the current working spectral range, and higher-order reflections are intrinsic to the crystal, which increases the overall signal seen in the data regions. The recorded data are the convolution of 1st order transmission, higher-order reflections, and the penumbra blurring. This work represents the details for deconvolving the 2nd and 3rd order spectral energy corrections with a penumbral de-blurring to correct the relative measurement of x-ray intensity of different spectral energies and further analysis of datasets relevant to the opacity experiments.

Experimental and numerical investigation of magneto-plasma optical properties toward measurements of opacity relevant for compact binary objects

Electromagnetic transients known as kilonovae (KN), are among the photonic messengers released in the post-merger phase of compact binary objects, for example, binary neutron stars, and they have been recently observed as the electromagnetic counterpart of related gravitational-wave (GW) events. Detection of the KN signal plays a fundamental role in the multi-messenger astronomy entering in a sophisticated GW-detecting network. The KN light curve also delivers precious information on the composition and dynamics of the neutron-rich post-merger plasma ejecta (relying on r-process nucleosynthesis yields). In this sense, studying KN becomes of great relevance for nuclear astrophysics. Because of the highly heterogeneous composition, plasma opacity has a great impact both on radiative transport and spectroscopic observation of KN. Theoretical models attempting in encoding the opacity of this system often fail, due to the complexity of blending plethora of both light- and heavy-r nuclei transition lines, requesting for more complete atomic database. Trapped magneto-plasmas conceived in PANDORA could answer to these requests, allowing experimental in-laboratory measurements of optical properties and opacities, at plasma electron densities and temperatures resembling early-stage plasma ejecta’s conditions, contributing to shed light on r-process metallic species abundance at the blue-KN diffusion time. A numerical study has been recently performed, supporting the choice of first physics cases to be investigated and the design of the experimental setup. In this article, we report on the feasibility of metallic plasmas on the basis of the results from the systematic numerical survey on optical spectra computed under non-local thermodynamic equilibrium (NLTE) for several light-r nuclei. Results show the great impact of the NLTE regime of laboratory magneto-plasmas on the gray opacity contribution contrasted with those under the astrophysical LTE assumption. A first experimental attempt of reproducing ejecta plasma conditions has been performed on the operative Flexible Plasma Trap (FPT) at the INFN-LNS and here presented, together with first plasma characterization of density and temperature, via non-invasive optical emission spectroscopy (OES). The measured plasma parameters have supported numerical simulations to explore optical properties of NLTE gaseous and metallic plasmas, in view of the near-future plasma opacity measurements through spectroscopic techniques. The novel work so far performed on these under-dense and low-temperature magneto-plasmas, opens the route for the first-time to future in-laboratory plasma opacity measurements of metallic plasma species relevant for KN light curve studies.