Magnetic Sector Research Articles

New beam delivery system design for industrial electron accelerator at Nuclear Science and Technology Research Institute, Iran

The output beams generated by industrial electron accelerators should be swept over the product. It is necessary to determine the exact scan length in order to ensure that an efficient dose reaches the product and to avoid the loss of the beam in contact with the sides of the product. Another challenge associated with scanning beams is the non-uniformity of the dose across the entire product during irradiation. In this study, the use of beam correction magnets is proposed for correcting products that receive a non-uniform dose. These magnets correct beams that are not swept in parallel. In addition, we simulated the dose received by the products in two non-uniform and uniform modes (modified by beam correction magnets) using the Monte Carlo method, and compared the results to assess the importance of using an appropriate irradiation system. Among the proposed magnets, a modified sector magnet is recommended for correcting the beam path and reducing the side effect. Using this magnet for a long horn does not require a cooling system, but using it for a short horn increases the need for a water-cooling system.

Surface Analysis by Secondary Ion Mass Spectrometry (SIMS): Principles and Applications from Swiss laboratories

Secondary Ion Mass Spectrometry (SIMS) extracts chemical, elemental, or isotopic information about a localized area of a solid target by performing mass spectrometry on secondary ions sputtered from its surface by the impact of a beam of charged particles. This primary beam sputters ionized atoms and small molecules (as well as many neutral particles) from the upper few nanometers of the sample surface. The physical basis of SIMS has been applied to a large range of applications utilizing instruments optimized with different types of mass analyzer, either dynamic SIMS with a double focusing mass spectrometer or static SIMS with a Time of Flight (TOF) analyzer. Here, we present a short review of the principles and major applications of three different SIMS instruments located in Switzerland.

Quasinormal modes of Proca fields in a Schwarzschild-AdS spacetime

We present new results concerning the Proca massive vector field in a Schwarzschild-AdS black hole geometry. We provide a first principles analysis of Proca vector fields in this geometry using both the vector spherical harmonic (VSH) separation method and the Frolov-Krtou\v{s}-Kubiz\v{n}\'{a}k-Santos (FKKS) method that separates the relevant equations in spinning geometries. The analysis in the VSH method shows, on one hand, that it is arduous to separate the scalar-type from the vector-type polarizations of the electric sector of the Proca field, and on the other hand, it displays clearly the electric and the magnetic mode sectors. The analysis in the FKKS method is performed by taking the nonrotating limit of the Kerr-AdS spacetime, and shows that the ansatz decouples the polarizations in the electric mode sector even in the nonrotating limit. On the other hand, it captures only two of the three possible polarizations, the magnetic mode sector is missing. The reason for the absence of this polarization is related to the degeneracy of the principal tensor in static spherical symmetric spacetimes. The degrees of freedom and quasinormal modes in both separation methods of the Proca field are found. The frequencies of the quasinormal modes are also computed. For the electric mode sector in the VSH method the frequencies are found through an extension, which substitutes number coefficients by matrix coefficients, of the Horowitz-Hubeny numerical procedure, whereas for the magnetic mode sector in the VSH method and the electric sector of the FKKS method it is shown that a direct use of the procedure can be made. The values of the quasinormal mode frequencies obtained for each method are compared and showed to be in good agreement with each other. This further supports the analytical approaches presented here for the behavior of the Proca field in a Schwarzschild-AdS black hole background.

Optimizing 40Ar/39Ar analyses using an Isotopx NGX-600 mass spectrometer

40Ar/39Ar geochronology relies on magnetic sector mass spectrometers to determine relative isotopic abundances. Ongoing technological developments within noble gas mass spectrometers over the last decade have led to analysis of increasingly smaller samples and higher precision, but also result in more complex data correction and interpretation. We describe a new multi-collector noble gas spectrometer, the Isotopx NGX-600, that is configured to optimize 40Ar/39Ar measurements. The NGX-600 is equipped with 9 Faraday collectors and one ion counting electron multiplier. Each Faraday is equipped with Isotopx ATONA® amplifier technology, enabling measurements spanning a dynamic range of amplified beam current from below 10−16 A to above 10−9 A. The performance of the NGX-600 is evaluated using both a conventional Nier-type ion source, and a next generation low temperature ion source, which allows for trap current variation from 200 μA to 1000 μA. We have performed over 3000 analyses of atmospheric argon to: (1) assess optimal measurement and integration times for blanks, baselines, and air aliquots of various ion intensities, (2) quantify the sensitivity via measurements of first principles 40Ar/39Ar standards, (3) compare the sensitivity between the conventional and new low temperature Nier-type ion sources, and (4) evaluate corrections associated with inter-Faraday biases, instrumental mass bias, and Faraday-multiplier gain. In addition to optimization experiments, we report a comparative analysis of both single crystal fusion and incremental heating data from Quaternary volcanic rocks obtained using both the 5-collector Nu Instruments Noblesse and the NGX-600 spectrometers.

Refractory elements in the gas phase for comet 67P/Churyumov-Gerasimenko

Context. Gas-phase sodium, silicon, potassium, and calcium were previously identified in mass spectra recorded in the coma of comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency’s Rosetta mission. The major release process for these atoms was identified as sputtering by the solar wind. More recently, remote observations of numerous comets over a range in heliocentric distances revealed the presence of metal atoms of iron and nickel that had been released either from the nucleus or from a distributed source with a short scale length. Sputtering, however, has been dismissed as a major release process due to the attenuation of the solar wind in the comae of some of the observed targets. Aims. We investigated the presence of refractory species in the gas phase of the coma of 67P/Churyumov-Gerasimenko. This investigation includes a period close to perihelion when the solar wind was likely absent from the near-nucleus region due to the increased cometary activity. Additionally, we extended our search to iron and nickel. Methods. We analyzed in situ data from the Rosetta/ROSINA Double Focusing Mass Spectrometer DFMS. Results. We found that gas-phase silicon was present throughout the Rosetta mission. Furthermore, the presence of sodium and iron atoms near the comet’s perihelion confirms that sputtering cannot be the sole release process for refractory elements into the gas phase. Nickel was found to be below the detection limit. The search for parent species of any of the identified gas phase refractories has not been successful. Upper limits for a suite of possible fragment species (SiH, SiC, NaH, etc.) of larger parent and daughter species have been obtained. Furthermore, Si did not exhibit the same drop in signal as do common cometary gases when the spacecraft is pointed away from the nucleus. The combined results suggest that a direct release of elemental species from small grains on the surface of the nucleus or from small grains in the surrounding coma is a more likely explanation than the previous assumption of release via the dissociation of gaseous parent molecules.

High-temperature mass spectrometric study of the thermodynamic properties in the Sm2 O3 -ZrO2 -HfO2 system.

The Sm2 O3 -ZrO2 -HfO2 system is a promising base for the development of a wide spectrum of new refractory materials. Reliable data on thermodynamic properties in this system are of significant importance for planning the preparation and application of high-temperature ceramics. Especially, they can be useful for calculation of the unknown phase equilibria in this system. The thermodynamic properties of the Sm2 O3 -ZrO2 -HfO2 system were studied by the high-temperature mass spectrometric method. The samples in the system under consideration synthesized by the solid-state method were vaporized from a tungsten twin effusion cell using a MS-1301 magnetic sector mass spectrometer. Ionization of the vapor species effusing from the cell was carried out by electrons at an energy of 25 eV. It was shown that, at temperatures below 2500 K, the main vapor species over the ceramics based on the Sm2 O3 -ZrO2 -HfO2 system were SmO, Sm, and O corresponding to vapor composition over pure Sm2 O3 . The SmO, Sm, and O partial vapor pressures over the samples and the Sm2 O3 activities were obtained in the temperature range 2319-2530 K. This allowed the excess Gibbs energy values to be determined. For comparison, the excess Gibbs energies in the Sm2 O3 -ZrO2 -HfO2 system were also calculated by the semi-empirical Kohler, Toop, Redlich-Kister, and Wilson methods and optimized by the statistical thermodynamic Generalized Lattice Theory of Associated Solutions (GLTAS). The thermodynamic data calculated by the semi-empirical approaches at 2423 K were shown to be lower than the experimental values. However, the Toop and Wilson methods were found to be useful for evaluation of the excess Gibbs energy values at the Sm2 O3 mole fraction less and higher than 0.32, respectively. The self-consistent thermodynamic description of the Sm2 O3 -ZrO2 -HfO2 system was derived at high temperatures by optimization of the experimental results using the GLTAS.

Lanthanoid analysis in seawater by seaFAST-SP3™ system in off-line mode and magnetic sector high-resolution inductively coupled plasma source mass spectrometer

Analysis of lanthanoids in seawater is challenging due to the complex matrix (∼35 g L−1 TDS) and low dissolved concentrations (in ng L−1). A 4-step strict analytical protocol and state-of-the-art technology were implemented and validated in this study. The 4-steps method involves the 1) sample filtration and acidification (pH<2); 2) pre-concentration by the matrix separation system, 3) off-line injection of the eluted sample; and 4) determination of lanthanoids by high-resolution inductively coupled plasma mass spectrometer (HR-ICP-MS). Since there are no certified values for lanthanoids in seawater are available, the method validation was done by analyzing SLEW-3 (estuarine water reference samples) and comparing with other reports and artificial seawater (100 ng L−1 lanthanoid multi-element standard solutions). SLEW-3 recovery varied from 78.6% to 106% and in artificial samples it ranged from 87 to 110%. Low recovery can be explained by complex organic in seawater, because the UV oxidation was not performed in the acidified samples. The variation was ≤10%, except for Gd, Tb, and Yb (11–13.75%). Blanks varied between 0.01 and 0.07 ng L−1, except for La and Ce (0.13–0.21 ng L−1). Blanks represent <5% SLEW-3 values and <1% synthetic seawater. The procedural detection limit varied from 0.01 to 0.03 ng L−1.•Lanthanoids as geochemical tracers in seawaters•A 4-step strict analytical protocol and state-of-the-art technology for lanthanoids analyses in seawaters•Sample pre-concentration system for matrix separation for the detection of ultra-low lanthanoids levels

Specialized mass spectrometer for determining the isotopic composition of lithium by ERIAD (electrospray with in source atomization)

A specialized isotope mass spectrometer for determining the isotopic ratio of lithium by ERIAD (electrospray with atomization in an ion source) is described. The device uses a Mattuha-Herzog-type mass analyzer with double focusing to use ion beams with a large spread in energy and simultaneous registration of signals of both lithium isotopes (6Li and 7Li), and a two-channel receiver based on a doublet of microchannel plates. The gas-dynamic interface is built according to the Kontorowitz-Gray scheme; from the gas-dynamic point of view, it is "long", that is, the distance between the nozzle and the skimmer is 4 times the size of the "Mach barrel" at the operating pressure (200 Pa). The device is desktop, its weight does not exceed 20 kg. The measurement time is 1000 s, sample replacement time is 100 s, measurement accuracy is ~ 0.1%. Keywords: mass spectrometry, electrospray, ion source, isotopes of lithium.

Panther — the new thermal neutron time-of-flight spectrometer at the ILL

Panther is a new high-flux medium-resolution direct-geometry thermal-neutron time-of-flight spectrometer at the Institut Laue-Langevin (ILL). It is designed for inelastic neutron-scattering measurements of excitations in condensed matter using single crystals, polycrystalline samples, and liquids. Panther uses double focusing graphite or Cu monochromators, a Fermi chopper, and position-sensitive 3He detectors covering 2 steradians of solid angle. A system of disc choppers and an optional sapphire filter are used to reduce the epithermal neutron background. Thermal neutron background is reduced by a radial oscillating collimator, a beam dump, and an elaborate set of Cd shielding inside the evacuated detector tank. The outside of the tank is covered by a 0.3 m thick layer of borated high-density polyethylene to reduce ambient and cosmic background. The design and performance of the instrument in its current status are described, as well as planned developments.

Formation of accumulative component of general mandatory state pension insurance as a direction of pension system reform

For more than thirty years, the problem of achieving an adequate level of pension benefits for citizens of Ukraine remains extremely relevant. Unfortunately, the current socio-economic and military-political situation indicates only a deterioration in the factors influencing the national pension system. The article analyzes the negative factors influencing the pension system, in particular the solidarity component. Thus, in recent years, the demographic situation in Ukraine has only worsened, as along with the natural processes of population depopulation, labor migration abroad continues, which, unfortunately, was supplemented by waves of refugees with the beginning of the war. The processes of de-shadowing of the economy, in particular the labor market, are also rather slow and inconsistent. Thus, in some sectors, about half of the workers may be informally employed. The pace of economic growth and the development of financial sector instruments have also not been very encouraging in recent years. Therefore, it is pointed out that all these factors have an extremely negative impact on the functioning of the joint pension system, moreover, for its financial stability, a significant share of funds from the state budget is redistributed annually. However, despite such significant financial costs, the level of adequacy of benefits for most retirees is extremely low. It is noted that one of the effective options to improve the level of pension provision of citizens is the introduction of a mandatory funded pension system, which in its content is designed: first - to supplement pension benefits to participants, and secondly - to diversify the risks of material impoverishment of such persons old age. The article analyzes the existing scenario for the introduction of such an accumulative component and the relevant government bill. The main advantages of the proposed system of mandatory pension capitalization are highlighted, as well as the main threats that may arise if it is implemented in its original form. Based on the results of the analysis, appropriate conclusions and recommendations were made.

Non-covalent anion structures in dissociative electron attachment to some brominated biphenyls.

The present work combines experiment and theory to reveal the behavior of bromo-substituted-biphenyls after an electron attachment. We experimentally determine anion lifetimes using an electron attachment-magnetic sector mass spectrometer instrument. Branching ratios of dissociative electron attachment fragments on longer timescales are determined using the electron attachment-quadrupole mass spectrometer instrument. In all cases, fragmentation is low: Only the Br- and [M-Br]- ions are detected, and [M-H]- is observed only in the case of 4-Br-biphenyl and parent anion lifetimes as long as 165 µs are observed. Such lifetimes are contradictory to the dissociation rates of 2- and 4-bromobiphenyl, as measured by the pulse radiolysis method to be 3.2 × 1010 and >5 × 1010s-1, respectively. The discrepancy is plausibly explained by our calculation of the potential energy surface of the dissociating anion. Isolated in vacuum, the bromide anion can orbit the polarized aromatic radical at a long distance. A series of local minima on the potential energy surface allows for a roaming mechanism prolonging the detection time of such weakly bound complex anions. The present results illuminate the behavior recently observed in a series of bromo-substituted compounds of biological as well as technological relevance.

Microanalysis using secondary ion emission By Raimond Castaing and Georges Slodzian

Secondary ion mass spectrometry (SIMS) is an analytical technique used to probe the composition of solids through the sputtering of the sample with a focussed primary ion beam and analyzing the emitted secondary ions generated under impact. These secondary ions ranging from elementals to low molecular weight organics offer precious information on the molecular composition and spatial organization within samples. Today, the combination of modern SIMS methodologies and instrumentation offers the most sensitive surface analysis approach, with elemental detection limits ranging from parts per million to parts per billion. In this month’s special feature article, we retrace the steps taken by Raimond Castaing and Georges Slodzian who in the early 1960’s developed a SIMS instrument based on a magnetic double focusing sector field mass spectrometer and using argon for the primary ion beam. This seminal work was first published in 1962, in French, in the Journal de Microscopie, which limited access to the scientific community at large. This article is now available in English and is beautifully prefaced by Georges Slodzian who revisits his steps as a young graduate student in the Castaing laboratory and discusses the scientific legacy of this article in the development of modern SIMS instrumentation.

Planetary Mass Spectrometry for Agnostic Life Detection in the Solar System

For the past fifty years of space exploration, mass spectrometry has provided unique chemical and physical insights on the characteristics of other planetary bodies in the Solar System. A variety of mass spectrometer types, including magnetic sector, quadrupole, time-of-flight, and ion trap, have and will continue to deepen our understanding of the formation and evolution of exploration targets like the surfaces and atmospheres of planets and their moons. An important impetus for the continuing exploration of Mars, Europa, Enceladus, Titan, and Venus involves assessing the habitability of solar system bodies and, ultimately, the search for life—a monumental effort that can be advanced by mass spectrometry. Modern flight-capable mass spectrometers, in combination with various sample processing, separation, and ionization techniques enable sensitive detection of chemical biosignatures. While our canonical knowledge of biosignatures is rooted in Terran-based examples, agnostic approaches in astrobiology can cast a wider net, to search for signs of life that may not be based on Terran-like biochemistry. Here, we delve into the search for extraterrestrial chemical and morphological biosignatures and examine several possible approaches to agnostic life detection using mass spectrometry. We discuss how future missions can help ensure that our search strategies are inclusive of unfamiliar life forms.

Characteristic Scales of Magnetic Switchback Patches Near the Sun and Their Possible Association With Solar Supergranulation and Granulation

Abstract Parker Solar Probe (PSP) data recorded within a heliocentric radial distance of 0.3 au have revealed a magnetic field dominated by Alfvénic structures that undergo large local variations or even reversals of the radial magnetic field. They are called magnetic switchbacks, they are consistent with folds in magnetic field lines within a same magnetic sector and are associated with velocity spikes during an otherwise calmer background. They are thought to originate either in the low solar atmosphere through magnetic reconnection processes or result from the evolution of turbulence or velocity shears in the expanding solar wind. In this work, we investigate the temporal and spatial characteristic scales of magnetic switchback patches. We define switchbacks as a deviation from the nominal Parker spiral direction and detect them automatically for PSP encounters 1, 2, 4, and 5. We focus in particular on a 5.1 day interval dominated by switchbacks during E5. We perform a wavelet transform of the solid angle between the magnetic field and the Parker spiral and find periodic spatial modulations with two distinct wavelengths, respectively consistent with solar granulation and supergranulation scales. In addition we find that switchback occurrence and spectral properties seem to depend on the source region of the solar wind rather than on the radial distance of PSP. These results suggest that switchbacks are formed in the low corona and modulated by the solar surface convection pattern.

Ion Kappa Distribution Parameters in the Magnetosphere of the Earth at Geocentric Distances Smaller Than 20 RE During Quiet Geomagnetic Conditions

AbstractThe Earth's magnetosphere is mainly a collisionless plasma system with non‐Maxwellian particle distributions, which are often fitted by the kappa function. While the Maxwell distribution function is described by two parameters (density and temperature), the kappa distribution function has three parameters: density, core energy, and the kappa index that characterizes the slope at high energies. In this study, we fitted an ion flux measured by the five Time History of Events and Macroscale Interactions during Substorms satellites in the Earth's magnetosphere during quiet geomagnetic conditions by a single kappa distribution function. The data were constrained to the following regions: from seven Earth Radii (7 ) to the Earth's magnetopause at the dayside, and up to 20 for other magnetic local time sectors. The two‐dimensional spatial distribution of the fitted parameters and their radial dependencies were analyzed. Regions of high and low ‐parameter are selected and their formation is discussed.

Elliptical Pearcey beam

In this paper, we extend a circular Pearcey beam (CPB) to an elliptical Pearcey beam (EPB) with the elliptical parameters t and θ theoretically and experimentally. In contrast to the CPB and the elliptical Airy beam, the EPB is more diverse and tunable, endowed with double focusing property due to the convergence process out of synchronization along the short axis and the long axis. We can flexibly adjust the normalized focusing intensity, the beam shape, the focusing position of the EPB by controlling the elliptical parameter. The experiment results match well with the theoretical ones. Additionally, the optical bottle is verified by embedding the vortex into the EPB, which can variegate the optical tweezers applications for multi microparticle manipulation.

Marchenko redatuming, imaging, and multiple elimination and their mutual relations

With the Marchenko method, it is possible to retrieve Green’s functions between virtual sources in the subsurface and receivers at the surface from reflection data at the surface and focusing functions. A macro model of the subsurface is needed to estimate the first arrival; the internal multiples are retrieved entirely from the reflection data. The retrieved Green’s functions form the input for redatuming by multidimensional deconvolution (MDD). The redatumed reflection response is free of internal multiples related to the overburden. Alternatively, the redatumed response can be obtained by applying a second focusing function to the retrieved Green’s functions. This process is called Marchenko redatuming by double focusing. It is more stable and better suited for an adaptive implementation than Marchenko redatuming by MDD, but it does not eliminate the multiples between the target and the overburden. An attractive efficient alternative is plane-wave Marchenko redatuming, which retrieves the responses to a limited number of plane-wave sources at the redatuming level. In all cases, an image of the subsurface can be obtained from the redatumed data, free of the artifacts caused by internal multiples. Another class of Marchenko methods aims at eliminating the internal multiples from the reflection data, while keeping the sources and receivers at the surface. A specific characteristic of this form of multiple elimination is that it predicts and subtracts all orders of internal multiples with the correct amplitude, without needing a macro subsurface model. Like Marchenko redatuming, Marchenko multiple elimination can be implemented as an MDD process, a double dereverberation process, or an efficient plane-wave oriented process. We have systematically examined the different approaches to Marchenko redatuming, imaging, and multiple elimination using a common mathematical framework.

The Scalable Plasma Ion Composition and Electron Density (SPICED) Model for Earth's Inner Magnetosphere

AbstractThe plasma mass loading of the terrestrial equatorial inner magnetosphere is a key determinant of the characteristics and propagation of ultra low frequency waves. Electron number density is also an important factor for other types of waves such as chorus, hiss and EMIC waves. In this paper, we use Van Allen Probe data from September 2012 to February 2019 to create average models of electron densities and average ion mass in the plasmasphere and plasmatrough, near the Earth's magnetic equator. These models are combined to provide an estimate of the most probable plasma mass density in the equatorial region. We then use machine learning to form a set of models which are parameterized by the SuperMAG ring current index based on the design of the average models. The resulting set of models are capable of predicting the average ion mass, electron density and plasma mass density in the range and over all magnetic local time sectors during a range of conditions where nT.

A New Ionospheric Index to Investigate Electron Temperature Small-Scale Variations in the Topside Ionosphere

The electron temperature (Te) behavior at small scales (both spatial and temporal) in the topside ionosphere is investigated through in situ observations collected by Langmuir Probes on-board the European Space Agency Swarm satellites from the beginning of 2014 to the end of 2020. Te observations are employed to calculate the Rate Of change of electron TEmperature Index (ROTEI), which represents the standard deviation of the Te time derivative calculated over a window of fixed width. As a consequence, ROTEI provides a description of the small-scale variations of Te along the Swarm satellites orbit. The extension of the dataset and the orbital configuration of the Swarm satellites allowed us to perform a statistical analysis of ROTEI to unveil its mean spatial, diurnal, seasonal, and solar activity variations. The main ROTEI statistical trends are presented and discussed in the light of the current knowledge of the phenomena affecting the distribution and dynamics of the ionospheric plasma, which play a key role in triggering Te small-scale variations. The appearance of unexpected high values of ROTEI at mid and low latitudes for specific magnetic local time sectors is revealed and discussed in association with the presence of Te spikes recorded by Swarm satellites under very specific conditions.

Observational Evidence of the Excitation of Magnetosonic Waves by an He++ Ion Ring Distribution

AbstractWe report plasma wave observations of equatorial magnetosonic waves at integer harmonics of the local gyrofrequency of doubly ionized helium (). The waves were observed by Van Allen Probe A on 08 Feb 2014 when the spacecraft was in the afternoon magnetic local time sector near inside of the plasmasphere. Analysis of the complementary in‐situ energetic ion measurements (1–300 keV) reveals the presence of a helium ion ring distribution centered near 30 keV. Theoretical linear growth rate calculations suggest that the local plasma and field conditions can support the excitation of the magnetosonic waves from the unstable ring distribution. This represents the first report of the generation of magnetosonic equatorial noise via a ring distribution in energetic ions in the near‐Earth space plasma environment.