Mass Bias Research Articles

Interferences and Matrix Effects on Iron Isotopic Composition Measurements by 57Fe-58Fe Double-Spike Multi-Collector Inductively Coupled Plasma Mass Spectrometry; the Importance of Calcium and Aluminum Interferences

Multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS) are widely used for Fe isotope measurements. The latter may be perturbed by interferences (notably from Cr and Ni) and matrix effects (notably from major elements), caused by elements remaining in the samples after purification. We quantified some of these perturbations and our ability to correct them whenever possible, using Thermo Neptune and Neptune Plus MC-ICPMS with a 57-58Fe double-spike mass bias correction. 54Cr and 58Ni isobaric interference corrections were found to be extremely efficient up to Cr/Fe=0.12 and Ni/Fe=0.04 (g/g natural Fe). Matrix effects were found negligible up to at least Na/Fe=175, Mg/Fe=10, K/Fe=1.5, and Mo/Fe=75 (g/g natural Fe). 28Si2+ interference was found negligible up to Si/Fe=50. Finally, we found that calcium and aluminum could cause significant interferences (e.g., 40Ca16O and 27Al2+), for Ca/Fe ≥ 2.5 and Al/Fe ≥ 2.5. The perturbation intensity relative to the Ca/Fe ratio was found dependent on the measurement conditions (plateau width). While working with samples with potentially high calcium or aluminum contents (such as calcite minerals or tests, bones and teeth, or marine samples and crustal rocks), we recommend to carefully take into account Ca and Al while tuning the instrument and checking the measurement accuracy with isotopic standards (i.e., doping the isotopic standard with Ca and Al levels comparable to those of the samples).

Single-Stage Extraction Technique for Ce Stable Isotopes and Measurement by MC-ICP-MS

The separation of Ce from other rare earth elements has not been well established because of their similar geochemical properties. In this study, we report a single-stage extraction technique to purify Ce from natural samples with Eichrom DGA resin. This method separates Ce effectively from matrices and interfering elements, such as Ba, La, and Nd. The Ce elution curve would not drift with different Ce loading masses and rock types. The Ce isotope compositions were measured using a Thermo Scientific Neptune Plus multicollector (MC)-inductively coupled plasma (ICP)-mass spectrometry (MS) instrument. The instrumental mass bias of Ce isotopes was corrected with a sample-standard bracketing combined with a Sm-doping method. The δ142Ce values of standard solutions (CDUT-Ce and JMC304) relative to National Institute of Standards and Technology SRM 3110 measured were +0.128 ± 0.028‰ (2SD, N = 30) and 0.005 ± 0.038‰ (2SD, N = 30), respectively. The reproducibility for δ142Ce was better than 0.040‰. The Ce isotopic compositions of nine United States Geological Survey standard rocks, including carbonatite, basalt, andesite, quartz latite, dolerite, rhyolite, and granodiorite, were measured in this study. Our result showed that δ142Ce values of these rocks varied slightly, indicating that insignificant fractionation occurred during igneous processes. The technique proposed in this study is simple and time-efficient, which is beneficial for further studies on Ce isotope geochemistry.

Novel nickel isolation procedure for a wide range of sample matrices without using dimethylglyoxime for isotope measurements using MC-ICP-MS

Nickel isotope ratios have traditionally been used as an important tracer in cosmochemistry, and recently, it has gained attention in geochemistry, biochemistry, and environmental sciences with the development of MC-ICP-MS. Purification of Ni before isotope measurement is mandatory for obtaining precise data, which has been commonly achieved with ion-exchange chromatography, employing dimethylglyoxime (DMG) as a chelating agent for Ni. However, it has been pointed out that the use of DMG can adversely affect the isotope measurement due to insufficient Ni recovery and mass bias during measurement caused by the remaining DMG. Ni isolation procedures without the usage of DMG were innovated, but they have disadvantages such as the necessity of complex separation methods, high Ni blank, and matrix-dependent Ni recovery. Here, we present a simple Ni isolation procedure without using DMG but with the aid of oxalic acid along with common inorganic acids, achieving near-complete recovery of Ni with low blanks [0.7 ± 0.3 ng (2SD, n = 4)] only using three ion exchange column steps. To validate our method and strengthen the Ni isotope database of reference materials, 60Ni/58Ni of 20 geological reference materials, covering wide matrix compositions, were measured by MC-ICP-MS using the double-spike method. The results have shown that high recovery of Ni, independent of the sample matrix elements was achieved (98 ± 4%) and the 60Ni/58Ni was measured with a 2SD of 0.006–0.084‰ from samples containing 100–200 ng Ni.

Certification of a Natural Silicon Reference Material with SI‐Traceable Isotopic Composition

Silicon (Si) is the second most abundant element in the continental crust. Studies have illustrated that silicon isotopes have a potential to be tracers in the biogeochemical silica cycle. This paper details a developed method for the production and certification of a new Si reference material with natural‐like isotopic composition using a fully calibrated multi‐collector inductively coupled plasma‐mass spectrometer (MC‐ICP‐MS). To correct for the mass bias effect, three blend solutions were gravimetrically prepared with isotopically enriched 28Si, 29Si and 30Si materials. Homogeneity and stability tests were performed, and no significant influences were found. Uncertainties of property values were evaluated, and the traceability to the International System of Units (SI) was established. The developed certified reference material (GBW04503) is a silicon powder (≈ 300 mesh) with high purity (≈ 0.999 99 kg kg−1), which can be used in silicon isotopic measurement to support validation of analytical procedures and/or quality control of gas source mass spectrometry (GS‐MS) or MC‐ICP‐MS. The certified isotope amount ratios of n(29Si)/n(28Si) and n(30Si)/n(28Si) are 0.050291(12) mol mol−1 and 0.033397(16) mol mol−1, respectively, (k = 2), and the certified isotope amount fractions of silicon are 92.2776(20)% (28Si), 4.6407(10) % (29Si) and 3.0818(14)% (30Si) (k = 2). Meanwhile, the delta value of δ30/28SiNBS 28 = 1.679(17)‰ was obtained (k = 2).

Neutron-induced mass shift of tin isotopes recognized using inductively coupled plasma mass spectrometry as an isotopic fingerprint on neutron reactions

The phenomenon of isotope shift in response to neutron irradiation was investigated. The high fission-neutron fluence of 1.44×1018 cm−2 from the second Egyptian research reactor (ETRR-2) was used to induce a mass shift in a metallic tin sample. A triple-quadrupole inductively coupled plasma mass spectrometry system was used to analyze the isotope abundances in the mass range from A=111 to A=125. The problem of mass bias due to kinetic fractionation on use of the inductively coupled plasma mass spectrometry system was treated by our calibrating the mass bias with a standard reference tin solution and building a response function. The response function was used to obtain absolute abundances in each mass range instead of isotope ratios. The results show that the mass shifts in the irradiated sample are dependent on the cross section of the neutron capture reaction in the tin isotopes.

Accurate analysis of Fe isotopes in Fe- dominated minerals by excimer laser ablation MC-ICP-MS on wet plasma conditions

The Fe isotope ratios can be a useful tracer of geochemistry, biogeochemistry, and the environmental redox state. In this study, we investigated the feasibility of Fe isotopic analysis in Fe-dominated minerals by 193 nm excimer ns laser ablation combined with Nu Plasma 1700 high resolution MC-ICP-MS without matrix-match calibration. Several important instrument parameters were investigated, such as the effect of the addition of nitrogen gas and water vapor, the effects of analytical parameters such as ablation mode, laser fluence, pulse repetition rate, spot size on Fe isotopic mass bias during analysis were investigated as well. The results showed that the effects of ablation mode, spot size, laser pulse repetition rate, and line scan speed can be neglected, while laser fluence and matrix effects had significant influence on the Fe isotopic mass bias at dry plasma condition. These problems can be minimized using consistent lower fluence (1.5‒3.5 J·cm-2), as well as the wet plasma conditions can significantly reduce the matrix effect in Fe isotopic analysis. Fortunately, with the water vapor and nitrogen gas addition after the ablation cell, an accurate and precise Fe isotope in pyrite, manganite, hematite, and chalcopyrite analysis by ns-LA-MC-ICP-MS can be achieved with non-matrix-matched calibration. The obtained accuracy and reproducibility of the in situ determinations of δ56FeIRMM-014 were both better than ± 0.10‰ (2 SD). This study indicated that there was a serious matrix effect in the Fe isotopic analysis of Fe-dominated minerals by ns- LA-MC-ICP-MS, and nitrogen gas mixed with water vapor-assisted ns- LA-MC-ICP-MS were an appealing option for the in situ Fe isotope analysis of Fe-dominated minerals with non-matrix-matched calibration.

Precise analysis of antimony isotopic composition in geochemical materials by MC-ICP-MS

Antimony (Sb) isotopes have been shown to be promising tracers for studying Sb cycling in the environment and its impact on ecosystem and human health. Yet precise measurements of Sb isotopic composition have been challenged by low Sb concentrations and high matrix effect and by the lack of a common reference material (zero-delta). Here we report an improved analytical scheme that is capable of high-precision measurement of Sb isotopes in environmental and geochemical samples. The method employs a two-column ion exchange set-up to remove interfering matrix elements to allow Sb isotopic measurements with low Sb (< 0.15 μg/g) and high matrix content. The instrument mass bias is corrected by combining the sample-standard bracketing method with internal normalization of cadmium. To allow for interlaboratory comparisons, a standard reference material certified for the total Sb concentration, NIST SRM 3102a, is recommended as the reference standard (“zero-delta”) for Sb isotope measurements. The improved method is applied for high-precision and high-accuracy Sb isotope composition measurements in environmental and geochemical reference samples with a minimum Sb required per analysis as low as 3.0 ng. By expressing our data and previously reported literature data against the same reference standard (NIST SRM 3102a), we provide an update on isotopic compositions of various types of environmental, geological and anthropogenic materials. The improved analytical method and database aid further studies on the mechanisms of Sb isotope fractionation and its application as a tracer for the study of the sources, processes and fate of Sb in the environment.

Scaling the peak and steady-state aerobic power of running and walking humans.

The first aim of this experiment was to evaluate the appropriateness of linear and non-linear (allometric) models to scale peak aerobic power (oxygen consumption) against body mass. The possibilities that oxygen consumption would scale allometrically across the complete metabolic range, and that the scaling exponents would differ significantly between basal and maximal-exercise states, were then evaluated. It was further hypothesised that the scaling exponent would increase in a stepwise manner with elevations in exercise intensity. Finally, the utility of applying the scaling exponent derived for peak aerobic power to another population sample was evaluated. Basal, steady-state walking and peak (treadmill) oxygen-consumption data were measured using 60 relatively homogeneous men (18-40year; 56.0-117.1kg), recruited across five mass classes. Linear and allometric regressions were applied, with the utility of each scaling method evaluated. Oxygen consumption scaled allometrically with body mass across the complete metabolic range, and was always superior to both ratiometric analysis and linear regression. The scaling exponent increased significantly from rest (mass0.57) to maximal exercise (mass0.75; P < 0.05), but not between steady-state walking (mass0.87) and maximal exercise (P > 0.05). When used with an historical database, the maximal-exercise exponent successfully removed the mass bias. It has been demonstrated that the oxygen consumption of healthy humans scales allometrically with body mass across the entire metabolic range. Moreover, only two scaling exponents (rest and exercise) were required to produce mass-independent outcomes from those data. Accordingly, ratiometric and linear regression analyses are not recommended as scaling methods.

Tracing the origin and core formation of the enstatite achondrite parent bodies using Cr isotopes

Enstatite achondrites (including aubrites) are the only differentiated meteorites that have similar isotope compositions to the Earth-Moon system for most of the elements. However, the origin and differentiation of enstatite achondrites and their parent bodies remain poorly understood. Here, we report high-precision mass-independent and mass-dependent Cr isotope data for 10 enstatite achondrites, including eight aubrites, Itqiy and one enstatite-rich clast in Almahatta Sitta, to further constrain the origin and evolution of their parent bodies. The ε54Cr (per 10,000 deviation of the mass bias corrected 54Cr/52Cr ratio from a terrestrial standard) systematics define three groups: main-group aubrites with ε54Cr = 0.06 ± 0.12 (2SD, N = 7) that is similar to the enstatite chondrites and the Earth-Moon system, Shallowater aubrite with ε54Cr = −0.12 ± 0.04 and Itqiy-type meteorites with ε54Cr = −0.26 ± 0.03 (2SD, N = 2). This shows that there were at least three enstatite achondrite parent bodies in the Solar System. This is confirmed by their distinguished mass-dependent Cr isotope compositions (δ53Cr values): 0.24 ± 0.03‰, 0.10 ± 0.03‰ and −0.03 ± 0.03‰ for main-group, Shallowater and Itqiy parent bodies, respectively. Aubrites are isotopically heavier than chondrites (δ53Cr = −0.12 ± 0.04‰), which likely results from the formation of an isotopically light sulfur-rich core. We also obtained the abundance of the radiogenic 53Cr (produced by the radioactive decay of 53Mn, T1/2 = 3.7 million years). The radiogenic ε53Cr excesses correlate with the 55Mn/52Cr ratios for aubrites (except Shallowater and Bustee) and also the Cr stable isotope compositions (δ53Cr values). We show that these correlations represent mixing lines that also hold chronological significance since they are controlled by the crystallization of sulfides and silicates, which mostly reflect the main-group aubrite parent body differentiation at 4562.5 ± 1.1 Ma (i.e., 4.8 ± 1.1 Ma after Solar System formation). Furthermore, the intercept of these lines with the ordinate axis which represent the initial ε53Cr value of main-group aubrites (0.50 ± 0.16, 2σ) is much higher than the average ε53Cr value of enstatite chondrites (0.15 ± 0.10, 2SD), suggesting an early sulfur-rich core formation that effectively increased the Mn/Cr ratio of the silicate fraction of the main-group aubrite parent body.

SPX Flow Inc, USA

Antimony (Sb) isotopes have been shown to be promising tracers for studying Sb cycling in the environment and its impact on ecosystem and human health. Yet precise measurements of Sb isotopic composition have been challenged by low Sb concentrations and high matrix effect and by the lack of a common reference material (zero-delta). Here we report an improved analytical scheme that is capable of high-precision measurement of Sb isotopes in environmental and geochemical samples. The method employs a two-column ion exchange set-up to remove interfering matrix elements to allow Sb isotopic measurements with low Sb (< 0.15 μg/g) and high matrix content. The instrument mass bias is corrected by combining the sample-standard bracketing method with internal normalization of cadmium. To allow for interlaboratory comparisons, a standard reference material certified for the total Sb concentration, NIST SRM 3102a, is recommended as the reference standard (“zero-delta”) for Sb isotope measurements. The improved method is applied for high-precision and high-accuracy Sb isotope composition measurements in environmental and geochemical reference samples with a minimum Sb required per analysis as low as 3.0 ng. By expressing our data and previously reported literature data against the same reference standard (NIST SRM 3102a), we provide an update on isotopic compositions of various types of environmental, geological and anthropogenic materials. The improved analytical method and database aid further studies on the mechanisms of Sb isotope fractionation and its application as a tracer for the study of the sources, processes and fate of Sb in the environment.

Factors Affecting the Robustness of Data Inversion for Stable Isotope Measurement Using the Double Spike Method: Insights from Chromium Isotope Analysis.

Stable isotope ratios are widely used to solve environmental, geological, medical, and forensic problems. The double spike technique is considered to be one of the most robust and efficient methods to correct for instrumental mass bias and isotopic fractionation that may occur during sample preparation. However, various hidden errors can arise from data processing and have been largely overlooked in previous studies. Several of these hidden errors were investigated in this work using measurement and synthetic data. Double spike inversion of chromium isotope raw data from 1116 natural samples demonstrated that averaging raw isotope ratios before double spike inversion can add significant errors to inverted isotope values, and such errors can be 1.5 times larger than the true analytical precision. Synthetic data were used to investigate the errors on inverted Cr isotope data caused by spike:analyte ratio and Fe-Ti-V interferences, and the following threshold values are recommended to minimize such errors: 54Crspike/52Crsample ratio greater than 0.5, 56Fe/52Cr less than 0.2, 49Ti/52Cr less than 0.04, and 51V/52Cr less than 1. Sample preparation can potentially lead to large errors in inverted Cr isotope data if preparation-induced isotope fractionation deviates from the exponential law used in the double spike inversion, but such errors can be minimized by achieving >70% Cr yield. Our findings provide important insights for the double spike inversion procedure and assessing the reliability of inverted isotope data for not only the chromium isotope system but also other elements commonly analyzed using the double spike technique.

Characterizing hydrostatic mass bias with mock-X

ABSTRACT Surveys in the next decade will deliver large samples of galaxy clusters that transform our understanding of their formation. Cluster astrophysics and cosmology studies will become systematics limited with samples of this magnitude. With known properties, hydrodynamical simulations of clusters provide a vital resource for investigating potential systematics. However, this is only realized if we compare simulations to observations in the correct way. Here we introduce the mock-X analysis framework, a multiwavelength tool that generates synthetic images from cosmological simulations and derives halo properties via observational methods. We detail our methods for generating optical, Compton-y and X-ray images. Outlining our synthetic X-ray image analysis method, we demonstrate the capabilities of the framework by exploring hydrostatic mass bias for the IllustrisTNG, BAHAMAS, and MACSIS simulations. Using simulation derived profiles we find an approximately constant bias b ≈ 0.13 with cluster mass, independent of hydrodynamical method, or subgrid physics. However, the hydrostatic bias derived from synthetic observations is mass-dependent, increasing to b = 0.3 for the most massive clusters. This result is driven by a single temperature fit to a spectrum produced by gas with a wide temperature distribution in quasi-pressure equilibrium. The spectroscopic temperature and mass estimate are biased low by cooler gas dominating the emission, due to its quadratic density dependence. The bias and the scatter in estimated mass remain independent of the numerical method and subgrid physics. Our results are consistent with current observations and future surveys will contain sufficient samples of massive clusters to confirm the mass dependence of the hydrostatic bias.

The Effects of Social Identities and Issue Involvement on Perceptions of Media Bias Against Gun Owners and Intention to Participate in Discursive Activities: In the Context of the Media Coverage of Mass Shootings

ABSTRACT This study examined how news audience’s predispositions (value and outcome involvement, political and gun ownership identities) predicted perceived media bias in mass shooting coverage against gun owners and intention to participate in discursive activities concerning gun issues. Republicans, strong identifiers of gun ownership, and those who perceived the outcome of tightening gun ownership would affect their lives predicted perceptions of media bias. Strong party identifiers, gun ownership identifiers, and those who displayed outcome involvement predicted intention to participate in discursive activities. Perceived media bias was not found to predict the intention to participate in discursive activities concerning gun issues. The results extended the theoretical discussion of corrective action hypothesis and increased our understanding of both individual-level (personal involvement) and social-psychological level (social identities) factors relevant to biased media perception.

Oxide Formation and Instrumental Mass Bias in MC‐ICP‐MS: An Isotopic Case Study of Neodymium

High rates of oxide formation affect the magnitude and behaviour of instrumental mass bias for Nd isotopic measurements performed with multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS) instruments, causing the traditional correction methods (e.g., internal and external normalisation) to fail. Here, we investigate the instrumental conditions that govern oxide formation and provide an extensive data set describing how different oxide formation rates affect the measurement error of Nd isotopic ratios. Results are reported for several instrumental set‐ups including wet and dry plasma, different introduction methods, the addition of N2, and various sampler and skimmer cone geometries. The differences in the behaviour of Nd isotopic ratios observed for dry and wet plasma require several reaction mechanisms to explain why oxide formation is associated with a non‐linear mass bias for some rare earth elements. We developed a simple mathematical model to describe the behaviour of Nd isotopic ratios for a range of oxide formation rates and different instrumental settings and present a qualitative model that predicts the isotopic offsets of Nd ratios based on the cumulative contributions of the major sources of mass bias. A series of analytical recommendations for the determination of accurate and precise Nd ratios by MC‐ICP‐MS is presented.

Neutrino mass constraints beyond linear order: cosmology dependence and systematic biases

We demonstrate the impact on forecasted neutrino mass constraints of improving galaxy clustering and CMB lensing predictions from linear to next-to-leading-order power spectra. The redshift-space 1-loop power spectrum model we adopt requires an additional four free bias parameters, a velocity bias parameter and two new stochastic parameters. These additional nuisance parameters appreciably weaken the constraints on M ν . CMB lensing plays a significant role in helping to alleviate these degeneracies and tighten the final constraints. The constraint on the optical depth to reionisation τ has a strong effect on the constraint on M ν , but only when CMB lensing is included in the analysis to keep the degeneracies with the nuisance parameters under control. We also extract constraints when 1) using the BAO signature only as a distance probe, and 2) isolating the scale-dependence of the power spectrum, which, as shown in previous work, provides a cosmology-independent probe of M ν . All constraints except the latter remain strongly sensitive to the assumption of a flat ΛCDM universe. We perform an analysis of the magnitude of the shift introduced in the inferred M ν value when neglecting nonlinear corrections, and show that, for a Euclid-like survey, this shift becomes roughly equal to the 1σ constraint itself even with a conservative cut-off scale of k max = 0.1 h Mpc-1. We also perform a calculation of the approximate expected bias in neutrino mass caused by not including the next, 2-loop order and expect a shift of only about 20% of the 1σ error for k max = 0.2 h Mpc-1 in a Euclid-like survey.

Cosmological Constraints from Galaxy Cluster Sparsity, Cluster Gas Mass Fraction, and Baryon Acoustic Oscillation Data

Abstract In recent years, the availability of large, complete cluster samples has enabled numerous cosmological parameter inference analyses using cluster number counts. These have provided constraints on the cosmic matter density Ω m and the amplitude of matter density fluctuations σ 8 alternative to that obtained from other standard probes. However, systematics uncertainties, such as the mass calibration bias and selection effects, may still significantly affect these data analyses. Hence, it is timely to explore other proxies of galaxy cluster cosmology that can provide cosmological constraints complementary to those obtained from cluster number counts. Here we use measurements of the cluster sparsity from weak-lensing mass estimates of the LC2-single and HSC-XXL cluster catalogs to infer constraints on a flat ΛCDM model. The cluster sparsity has the advantage of being insensitive to selection and mass calibration bias. On the other hand, it primarily constrains a degenerate combination of Ω m and σ 8 (along approximately constant curves of and, to a lesser extent, the reduced Hubble parameter h. Hence, in order to break the internal parameter degeneracies, we perform a combined likelihood analysis of the cluster sparsity estimates with cluster gas mass fraction measurements and BAO data. We find marginal constraints that are competitive with those from other standard cosmic probes: Ω m = 0.316 ± 0.013, σ 8 = 0.757 ± 0.067 (corresponding to S 8 = 0.776 ± 0.064), and h = 0.696 ± 0.017 at 1σ. Moreover, assuming a conservative Gaussian prior on the mass bias of gas mass fraction data, we find a lower limit on the gas depletion factor Y b,500c ≳ 0.89.

Accuracy and reliability of the InBody 270 multi-frequency body composition analyser in 10-12-year-old children.

The aim of this study was at examining the validity and reliability of a marketed bioimpedance (BIA) scale for body composition assessment, in children engaged in an educational football project (FIFA 11 for Health). One-hundred and twenty-seven children (70 boys and 57 girls; age 10.7±0.5 years, body mass 41.2±9.0 kg, Body mass index 18.5±3.3 kg·m-2 and stature 149±7 cm) were evaluated for total body mass, lean body mass, muscle mass, using BIA (InBody 270, Biospace, California, USA) and dual-energy X-ray absorptiometry (DEXA, Lunar Prodigy, GE Medical Systems, Madison, Wisconsin, USA), at baseline conditions. Data analyses were carried out separately for girls and boys. Nearly perfect associations (r = 0.97−0.99) and excellent absolute (TEM = 0.04−1.9%) and relative (ICC = 0.98−1.00) inter-device reliability were found between DEXA and BIA variables. Fat and lean body mass bias (p < .0001) were practically relevant both for the boys (2.56 and 11.22 kg, respectively) and the girls (2.33 and 10.49 kg, respectively). Muscle mass and body fat were underestimated and overestimated, respectively, for the boys and girls. InBody 270 is a valid BIA system for estimating body composition with an excellent inter-device relative and absolute reliability. However, the remarkable measurements bias of BIA fat and muscle mass values discourage its use for clinical prescription. The BIA body composition biases were sex dependent.

Determination of the Isotopic Composition of Zirconium Using MC-ICPMS and a Regression Model for Mass Bias Correction.

Measurements of zirconium isotopes provide insights into the formation of planetary bodies, dating nuclear explosions, or maintenance of nuclear reactors. Although many comparative measurements for the isotopic composition of zirconium have been performed using mass spectrometry, there is a lack of zirconium isotopic reference materials and only a single calibrated measurement has been reported to date by total evaporation thermal ionization mass spectrometry (TE-TIMS). In this study, we report an independent measurement of full zirconium isotopic composition in a new zirconium isotopic reference material by multicollector inductively coupled plasma MS using the regression method and two independent certified isotopic reference materials, NIST SRM 984 Rb and NIST SRM 987 Sr. Our results agree well with the recent TE-TIMS measurements and suggest a revision of the standard atomic weight of zirconium.

Charged black hole mergers: orbit circularisation and chirp mass bias

We consider the inspiral of black holes carrying U(1) charge that is not electromagnetic, but corresponds to some dark sector. In the weak-field, low-velocity regime, the components follow Keplerian orbits. We investigate how the orbital parameters evolve for dipole-dominated emission and find that the orbit quickly circularises, though not as efficiently as for a gravitationally dominated emission. We then regard circular orbits, and look for modifications in the gravitational waveform from the components carrying small charges. Taking this into account we populate the waveform with simplified LIGO noise and put it through a matched filtering procedure where the template bank only consists of uncharged templates, focusing on the charges’ effect on the chirp mass estimation. We find a consistent overestimation of the ‘generalised’ chirp mass, and a possible over- and underestimation of the actual chirp mass. Finally, we briefly consider the effect of such charges on hyperbolic encounters, finding again a bias arising from interpreting the generalised chirp mass as the actual chirp mass.

Super sample covariance of the thermal Sunyaev-Zel’dovich effect

The thermal Sunyaev-Zel'dovich (tSZ) effect is a powerful probe of cosmology. The statistical errors in the tSZ power spectrum measurements are dominated by the presence of massive clusters in a survey volume that are easy to identify on individual cluster basis. First, we study the impact of super sample covariance (SSC) on the tSZ power spectrum measurements, and find that the sample variance is dominated by the connected non-Gaussian (cNG) covariance arising mainly from Poisson number fluctuations of massive clusters in the survey volume. Second, we find that removing such individually-detected, massive clusters from the analysis significantly reduces the cNG contribution, thereby leading the SSC to be a leading source of the sample variance. We then show, based on Fisher analysis, that the power spectrum measured from the remaining diffuse tSZ effects can be used to obtain tight constraints on cosmological parameters as well as the hydrostatic mass bias parameter. Our method offers complementary use of individual tSZ cluster counts and the power spectrum measurements of diffuse tSZ signals for cosmology and intracluster gas physics.