Iron Nuclei Research Articles

Investigating the Cherenkov light lateral distribution function for primary proton and iron nuclei in extensive air showers

The lateral distribution function (LDF) of Cherenkov radiation in extensive air showers (EAS) was simulated by CORSIKA program for the conditions of Yakutsk Cherenkov array at the high energy range (1013–1016) eV for two primary particles (p and Fe) for different zenith angles. By depending on Breit-Wigner function for analyzing of Cherenkov light LDF, a parameterization of Cherenkov light LDF was reconstructed by depending on CORSIKA simulation as a function of primary energy. The comparison between the estimated Cherenkov light LDF with the LDF that measured on the Yakutsk EAS array gives the ability of particle identification that initiated the shower and determination of particle’s energy around the knee region. The extrapolation of approximated Cherenkov light LDF for energies 20 and 30 PeV was obtained for primary particles (p and Fe).

Influence of Reduction Condition on the Morphology of Newly Formed Metallic Iron During the Fluidized Bed Reduction of Fine Iron Ores and its Corresponding Agglomeration Behavior

The fine iron ores from Chile are reduced in a laboratory fluidized bed at 973–1173 K with CO–H2–CO2 mixtures to investigate the influence of reduction condition on the morphology of newly formed metallic iron and its corresponding agglomeration behavior. The results reveal that the addition of H2 in CO accelerates the moving rate of the Fe/Fe1–xO interface and increases the amount of the iron nucleus formed during the initial reduction period, which induce the transformation of iron morphology from fibrous to dense. The presence of CO2 in CO makes the fibrous iron shorter and sparser, especially when the content of CO2 is 30% (by volume), the iron appears as “cactus‐like.” The increase of reduction temperature makes the fibrous iron stronger and more active. The sticking index indicates that the long and strong iron whiskers are prone to form stable agglomerates even at a low metallization degree, but the dense iron trends to behave separate. Furthermore, based on the precipitation mechanism of iron proposed by the authors, it is manifested that the agglomeration behavior of the fine iron ores could be controlled by pre‐reduction in H2‐rich reducing gas (H2/(H2 + CO) ≥ 30%, by volume).

Development of Yangbajing air shower core detector for a new EAS hybrid experiment**Supported by grants from the National Natural Science Foundation of China (11078002, 11275212, 11165013), the Chinese Academy of Sciences (H9291450S3, Y4293211S5) and the Knowledge Innovation Fund of Institute of High Energy Physics (IHEP), China (H95451D0U2, H8515530U1)

Aiming at the observation of cosmic-ray chemical composition in the “knee” energy region, we have been developing a new type of air-shower core detector (YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing (90.522° E, 30.102° N, 4300 m above sea level, atmospheric depth: 606 g/m2) in Tibet, China. YAC works together with the Tibet air-shower array (Tibet-III) and an underground water Cherenkov muon detector array (MD) as a hybrid experiment. Each YAC detector unit consists of lead plates of 3.5 cm thickness and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores. The burst size can be measured from 1 MIP (Minimum Ionization Particle) to 106 MIPs. The first phase of this experiment, named “YAC- I”, consists of 16 YAC detectors each with a size of 40 cm×50 cm and distributed in a grid with an effective area of 10 m2. YAC- I is used to check hadronic interaction models. The second phase of the experiment, called “YAC- II”, consists of 124 YAC detectors with coverage of about 500 m2. The inner 100 detectors of 80 cm×50 cm each are deployed in a 10×10 matrix with a 1.9 m separation; the outer 24 detectors of 100 cm×50 cm each are distributed around these to reject non-core events whose shower cores are far from the YAC- II array. YAC- II is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of protons, helium and iron nuclei between 5×1013 eV and 1016 eV, covering the “knee” and also connected with direct observations at energies around 100 TeV. We present the design and performance of YAC- II in this paper.

Measurement of the cosmic-ray energy spectrum above 1016 eV with the LOFAR Radboud Air Shower Array

The energy reconstruction of extensive air showers measured with the LOFAR Radboud Air Shower Array (LORA) is presented in detail. LORA is a particle detector array located in the center of the LOFAR radio telescope in the Netherlands. The aim of this work is to provide an accurate and independent energy measurement for the air showers measured through their radio signal with the LOFAR antennas. The energy reconstruction is performed using a parameterized relation between the measured shower size and the cosmic-ray energy obtained from air shower simulations. In order to illustrate the capabilities of LORA, the all-particle cosmic-ray energy spectrum has been reconstructed, assuming that cosmic rays are composed only of protons or iron nuclei in the energy range between ∼2 × 1016 and 2 × 1018 eV. The results are compatible with literature values and a changing mass composition in the transition region from a Galactic to an extragalactic origin of cosmic rays.

On the determination of source spectrum of ultra high energy cosmic rays

The calculations of source spectra of extragalactic cosmic rays with ultra high energies are made based on the solution of inverse problem for a system of transport equations that describes the propagation of protons and nuclei with energies 1018 to 1021 eV in the expanding Universe filled with the background radiation. It is assumed that protons and Iron nuclei are the most abundant species in the sources. The data from the Auger experiment is used to illustrate the method.

Cosmic rays: the spectrum and chemical composition from 1010 to 1020 eV

The production of energetic particles in the universe remains one of the great mysteries of modern science. The mechanisms of acceleration in astrophysical sources and the details about the propagation through the galactic and extragalactic media are still to be defined. In recent years, the cosmic ray flux has been measured with high precision in the energy range from 1010 to 1020.5 eV by several experiments using different techniques. In some energy ranges, it has been possible to determine the flux of individual elements (hydrogen to iron nuclei). This paper explores an astrophysical scenario in which only our Galaxy and the radio galaxy Cen A produce all particles measured on Earth in the energy range from 1010 to 1020.5 eV . Data from AMS-02, CREAM, KASCADE, KASCADE-Grande and the Pierre Auger Observatories are considered. The model developed here is compared to the total and if available to the individual particle flux of the experiments considered.The flux of each element as determined by AMS-02, CREAM, KASCADE and KASCADE-Grande and the mass sensitivity parameter Xmax measured by the Pierre Auger Observatory above 10^ eV are also explored within the framework of the model. The transition from 1016 to 1018 eV is carefully analyzed. It is shown that the flux measured in this energy range suggest the existence of an extra component of cosmic rays yet to be understood.

Ensemble fluctuations of the cosmic ray energy spectrum and the intergalactic magnetic field

The origin of the most energetic cosmic ray particles is one of the most important open problems in astrophysics. Despite a big experimental effort done in the past years, the sources of these very energetic particles remain unidentified. Therefore, their distribution on the Universe and even their space density are still unknown. It has been shown that different spatial configurations of the sources lead to different energy spectra and composition profiles (in the case of sources injecting heavy nuclei) at Earth. These ensemble fluctuations are more important at the highest energies, because only nearby sources, which are necessarily few, can contribute to the flux observed at Earth. This is due to the interaction of the cosmic rays with the low energy photons of the radiation field, present in the intergalactic medium, during propagation. It is believed that the intergalactic medium is permeated by a turbulent magnetic field. Although at present it is still unknown, there are several constraints for its intensity and coherence length obtained from different observational techniques. Charged cosmic rays are affected by the intergalactic magnetic field because of the bending of their trajectories during propagation through the intergalactic medium. In this work, the influence of the intergalactic magnetic field on the ensemble fluctuations is studied. Sources injecting only protons and only iron nuclei are considered. The ensemble fluctuations are studied for different values of the density of sources compatible with the constraints recently obtained from cosmic ray data. Also, the possible detection of the ensemble fluctuations in the context of the future JEM-EUSO mission is discussed.

Cavity with Iron Nuclei Slows Down X Rays

In vacuum, the propagation of photons proceeds with the same speed for each color (or frequency) of light. A laser pulse, corresponding to a broad range of frequencies, will thus propagate in vacuum without any deformation or delay. However, if the pulse enters a medium with an index of refraction that depends strongly on the frequency, then some colors will travel faster than others, causing a change in the overall pulse. In some cases this dispersion can slow down light [1, 2], so that photons at the end of the pulse catch up to those at the front of the pulse. In this way, slow light propagation can yield higher densities of photons, i.e., higher intensities, inside the medium, which can be used to explore nonlinear and/or quantum effects in the light-matter interactions. Slow light has been studied extensively at visible frequencies, but recent work has begun to explore related phenomena in x rays [3]. Kilian Heeg of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, and his colleagues have measured slow x rays in a dispersive system [4]. The team directed x rays from a synchrotron source into a specially designed cavity and recorded a time delay in the outgoing light, which implied a speed decrease by 4 orders of magnitude. Further progress will help to concentrate high-energy light for nonlinear x-ray optics with possible applications, e.g., in super-resolved imaging or in quantum optics and quantum cryptography in the x-ray regime.

Investigating the Characteristics of Longitudinal Profile of Primary Particles in Extensive Air Showers

One of the characteristics of longitudinal development of extensive air showers is the number of charged particles and depth of shower maximum in extensive air showers as a function of primary energy, which is often used to reconstruct the elemental composition of primary cosmic rays. Studying of extensive air shower characteristics was performed by investigating the longitudinal development parameters depending on Heitler model for different primary particles. The simulation of the number of charged particles and depth of shower maximum (NandXmax) in extensive air showers of particle cascades was performed using AIRES code for SIBYLL hadronic model for different primary particles like electron, positron, gamma quanta and iron nuclei at the energy range 1014-1019eV. The comparison between the simulated longitudinal development ofNandXmaxusing SIBYLL hadronic model with two hadronic models (QGSJET99 ans SIBYLL16) has shown an opportunity for determination of cosmic ray cascade interactions in extensive air showers.

Estimating of Cherenkov Radiation in Extensive Air Showers Using CORSIKA Code for Tunka133 EAS Cherenkov Array

The simulation of Cherenkov light Lateral distribution function (LDF) in Extensive Air Showers (EAS) initiated primary particles such as primary calcium, argon, proton iron nuclei, neutron and nitrogen have been performed using CORSIKA program for conditions and configurations of Tunka133 EAS Cherenkov array. The simulation was fulfilled at the high energy range 1014-1016eV for four different zenith angles 0o, 10o, 15oand 30o. The results of the simulated Cherenkov light LDF are compared with the measurements of Tunka133 EAS array for the same particles and energy range mentioned above. This comparison may give the good ability to reconstruct the energy spectrum and mass composition of the primary cosmic ray particles in EAS. The main feature of the given approach consists of the possibility to make a library of Cherenkov light LDF samples which could be utilized for analysis of real events which can be detected with different EAS arrays and reconstruction of the primary cosmic rays energy spectrum and mass composition of EAS particles.

Hyperfine fields at 57Fe in dilute iron-based alloys determined by Mössbauer spectroscopy

The room temperature Mössbauer spectra of 57Fe were measured for several dilute iron-based alloys, Fe1−xDx (D = Co, Cr, Mn, Mo, Pt, Re, Ta, V, W), annealed at 1270 K for 2 h before the measurements. The analysis of the spectra shows that the effective hyperfine field B at 57Fe nuclei depends on the concentration x of the minority component of the alloys under consideration and the dependence is different for iron nuclei having unlike numbers of impurities in their neighbourhood. The latter is at variance with previously published data, which suggest that the general B(x) dependence is common for all impurity configurations present in the vicinity of iron nuclei.

Inverse problem for extragalactic transport of ultra-high energy cosmic rays

The energy spectra and composition of ultra-high energy cosmic rays are changing in a course of propagation in the expanding Universe filled with background radiation. We developed a numerical code for solution of inverse problem for cosmic-ray transport equations that allows the determination of average source spectra of different nuclei from the cosmic ray spectra observed at the Earth. Employing this approach, the injection spectra of protons and Iron nuclei in extragalactic sources are found assuming that only these species are accelerated at the source. The data from the Auger experiment and the combined data from the Telescope Array + HiRes experiments are used to illustrate the method.

Spectra of abundant nuclei in sources, according to the ATIC experiment

One of the most important results from the ATIC experiment is its collection of the energy spectra of abundant cosmicray nuclei: protons, He, C, O, Ne , Mg, Si, and Fe, measured in terms of energy per par� ticle in the energy range of 50 GeV to tens of TeV. Starting with the spectra measured in the ATIC experiment, abundant nuclei spectra in sources are calculated using a number of propagation models. The results from comparing the spectra in sources of different nuclei are shown to depend only weakly on the propagation model. The spectrum of helium in sources is found to be harder than that of protons; this result is of high sta� tistical significance and is virtually modelindependent. From helium up to iron nuclei, the steepness of the spectra in sources is seen to grow notably as the charge of nuclei rises.

Identifying the spectra of ultrahigh energy cosmic rays from extragalactic sources

The energy spectra of extragalactic sources of cosmic rays are calculated by solving an inverse problem of the transport of cosmic rays with energies of 1018–1021 eV in a Universe filled with background electromagnetic radiation. Calculations are performed using cosmic-ray spectra measured on Earth in Auger experiments. It is assumed that protons and iron nuclei dominate in the composition of a source.

Determining the depth of the maximum of the cascade curve from the muon component at the Yakutsk EAS array

The lateral distribution of muons with threshold Eμ ≈ 1.0secθ GeV in extensive air showers with energies E0 ≥ 1017 eV for the observation period of 2011–2013 is investigated. The observations show that in the energy range of 1–5 ×1017 eV, the depth of the maximum Xm on the cascade curve grows relatively quickly, due to the composition of cosmic rays changing from predominantly iron nuclei to protons at E0 ≈ 1017 eV.

Acceleration of the iron nuclei by light

光，すなわち超高強度短パルスレーザーと，固体薄膜とを相互作用させることで，ほぼフルストリップ状態の鉄の原子核を0.9GeVで加速して取り出すことに成功した。既存の加速器イオン源技術ではなかなか達成が難しいと考えられる多価重イオンを数十フェムト秒という極短時間で作り出し，同時に高エネルギーに加速できることを実験的に示した。まったく新しいタイプの小型のイオン源開発に一歩前進したと言える。

Depth of maximum of air-shower profiles at the Pierre Auger Observatory. II. Composition implications

Using the data taken at the Pierre Auger Observatory between December 2004 and December 2012, we have examined the implications of the distributions of depths of atmospheric shower maximum (Xmax), using a hybrid technique, for composition and hadronic interaction models. We do this by fitting the distributions with predictions from a variety of hadronic interaction models for variations in the composition of the primary cosmic rays and examining the quality of the fit. Regardless of what interaction model is assumed, we find that our data are not well described by a mix of protons and iron nuclei over most of the energy range. Acceptable fits can be obtained when intermediate masses are included, and when this is done consistent results for the proton and iron-nuclei contributions can be found using the available models. We observe a strong energy dependence of the resulting proton fractions, and find no support from any of the models for a significant contribution from iron nuclei. However, we also observe a significant disagreement between the models with respect to the relative contributions of the intermediate components.

Dependence of the muon pseudorapidity on the cosmic ray mass composition around the knee

In order to identify the mass composition of cosmic rays (CRs), we have investigated the mean muon pseudorapidity (〈η〉) values of muonic component in extensive air showers (EASs). For this purpose we have simulated EASs by CORSIKA 7.4 code for Hydrogen, Oxygen and Iron nucleus. The energy range was selected between 1014 eV and 1016 eV with zenith angle from 0°–18°. We have compared our calculations with KASCADE muon tracking detector (MTD) measurements to obtain results on the primary mass relationship with mean muon pseudorapidity values of EASs muonic component. It is shown that after the knee energies, experimental data tend to the heavy primaries and mass composition becomes heavier. Finally, linear equations between the mass of primary and mean η values for different energies are obtained.

Study of solid state reactions during mechanical alloying of Si–Fe system with first-principles calculation

Former experiments showed that, at early stages, mechanical alloying of iron with silicon produces a disilicide α-FeSi2. First-principles calculations of isomer shift and quadrupole splitting (electric field gradient) at iron nuclei have been conducted for α-FeSi2 with account of different defects of lattice. The results obtained have been used for interpretation of a row of recent experiments on mechanical alloying of Si–Fe system. The results on the hyperfine interactions can be used in studying the solid state reactions that occur during mechanical alloying and further annealing, with the help of Mossbauer spectroscopy.

Determination of the cascade-curve maximum depth from the muon component on the Yakutsk EAS array

The lateral distribution of muons with a threshold E µ secθ GeV in extensive air showers with E 0 ≥ 1017 eV over the period of observations on the Yakutsk array from November 2011 to June 2013 has been investigated. It follows from this distribution that the cascade-curve maximum depth X m in the energy range (1–5) × 1017 eV increases relatively rapidly, because the cosmic-ray composition changes from iron nuclei dominating at E 0 ≈ 1017 eV to protons.