Penetration Of Rays Research Articles

Self-consistent theory of cosmic ray penetration into molecular clouds: Relativistic case

We study penetration of interstellar cosmic rays (CRs) into molecular clouds surrounded by nonuniform diffuse envelopes. The present work generalizes our earlier model of CR self-modulation [Ivlev ; Dogiel ], in which the value for the envelope’s gas density where CRs excite MHD waves was treated as a free parameter. Now, we investigate the case where the density monotonically increases toward the center. Assuming that CRs are relativistic, we obtain a universal analytical solution which does not depend on the particular shape of gas distribution in the envelope, and self-consistently derive boundaries of the diffusion zone formed within the envelope, where CRs are scattered at the self-excited waves. The values of the gas density at the boundaries are found to be substantially smaller than those assumed in the earlier model, which leads to a significantly stronger modulation of penetrating CRs. We compute the impact of CR self-modulation on the gamma-ray emission and show that the results of our theoretical model are in excellent agreement with recent observations of nearby giant molecular clouds by Yang []. Published by the American Physical Society 2024

Variations in the Solar Modulation Parameter Over the Last 9.5 Thousand Years and the Tilt of the Geomagnetic Dipole

Background: Calculations of the solar modulation parameter (Φ) over the past millennia typically use the relationship between the production rate of cosmogenic isotopes, the earth's dipole moment, and the magnitude of Φ. The cosmogenic isotopes 14C and 10Be are typically used in these studies. When studying solar modulation, the cyclic change in dipole tilt is usually not taken into account, which affects estimates of past solar activity. Methods: Tree rings are a reliable basis for obtaining a radiocarbon time scale (IntCal13). However, determining the concentration of 14C in tree rings is a difficult and controversial task. The time scale derived from the 10Be production rate simulation (GICC05) is less reliable. Nevertheless, there is a way to combine the accuracy of the radiocarbon time scale with the reliability of estimates of the 10Be production rate. This method is the synchronization of the radiocarbon and beryllium-10 series. We have selected the most relevant methods for calculating the solar modulation parameter Φ for the Holocene. When calculating Φ, 10Be data synchronized with 14C data were used. The latest data on the earth's dipole moment were considered. Empirical Mode Decomposition (EMD) was used in the analysis of Φ. Results: It has been shown that the first two decomposition modes are oscillating components with periods of 710 and 208 years, the amplitudes of which increase with time, reaching a maximum of 2500 BP. From contemplation, it follows that the 710-year oscillations are apparently caused by fluctuations in the tilt of the earth's dipole. After excluding the EMD component associated with the 710-year cyclicity, a corrected series was obtained for the solar modulation parameter, free from the influence of changes in the tilt of the magnetic dipole. Conclusion: The rate of formation of cosmogenic radionuclides depends on the intensity of penetration of Galactic Cosmic Rays (GCRs) into the earth's atmosphere. Before reaching earth, GCRs must cross the heliosphere, where they are exposed to solar modulation. Adequate consideration of solar modulation parameters is important for the correct interpretation of the rate of production of cosmogenic isotopes and solar activity.

Optimizing Sensor Positions in the Stress Wave Tomography of Internal Defects in Hardwood

Stress wave tomography technology uses instruments to collect stress wave velocity data via sensors, visualizes those velocity data, and reconstructs an image of internal defects using estimated velocity distribution. This technology can be used to detect the size, position, and shape of internal defects in hardwood, and it has increasingly attracted the attention of researchers. In order to obtain enough stress wave signals, 12 sensors are usually equidistantly positioned around the cross-section of trunks like a clock. Although this strategy is reasonable and convenient, it is obviously not the optimal signal acquisition strategy for all defects. In this paper, a novel sensor position’s optimization method for high-quality stress wave tomography is proposed. The relationship between the shape of defects and the planar distribution of sensors is established by taking the ray penetration ratio and degree of equidistant distribution of sensors as indicators. Through the construction of the fitness function and optimization conditions, the optimal strategy for the planar distribution of sensors was determined using the Genetic Algorithm. Seven samples containing simulated defects and real tree trunks were used to test the proposed algorithm, and the comparison results show that the image of internal defects in hardwood can be reconstructed with high accuracy after optimizing the sensor positions.

Development of innovative equipment for milk microflora inactivation

The article is dedicated to the development of innovative equipment for the inactivation of milk microflora. It provides an analysis of existing methods to suppress the growth and destruction of microorganisms in milk, aiming to enhance product quality indicators. The advantages and disadvantages of current pasteurization equipment are highlighted. An overview of alternative methods for milk inactivation is presented, focusing on the impact of ultraviolet radiation on bacteria and lower organisms. It is concluded that a major advantage of ultraviolet (UV) milk treatment, in addition to its bactericidal effect, is its minimal impact on proteins under efficient operating conditions. Considering the limited penetration of UV rays into milk, a device is proposed—a milk disinfection separator that separates microorganisms from the main product by placing them in the form of a thin laminar film accessible for effective irradiation. Special attention is given to justifying the parameters of the UV irradiation section. The methodology for hydraulic calculation of device movement is presented, along with a method for determining the bactericidal effectiveness of UV irradiation on microorganisms and the necessary lethal dose for this purpose. By specifying the system's productivity, knowing the bactericidal dose required to deactivate bacteria, and considering the irradiation intensity of the UV source, the dimensions of the irradiation section and the required electrical power of the equipment are determined. The article proposes modern LED arrays with the necessary UV wavelength range, along with diagrams for their connection and equipment control.

The GEM-handle as convenient labeling strategy for bimodal single-domain antibody-based tracers carrying 99mTc and a near-infrared fluorescent dye for intra-operative decision-making.

Intra-operative fluorescence imaging has demonstrated its ability to improve tumor lesion identification. However, the limited tissue penetration of the fluorescent signals hinders the detection of deep-lying or occult lesions. Integrating fluorescence imaging with SPECT and/or intra-operative gamma-probing synergistically combines the deep tissue penetration of gamma rays for tumor localization with the precision of fluorescence imaging for precise tumor resection. In this study, we detail the use of a genetically encoded multifunctional handle, henceforth referred to as a GEM-handle, for the development of fluorescent/radioactive bimodal single-domain antibody (sdAb)-based tracers. A sdAb that targets the urokinase plasminogen activator receptor (uPAR) was engineered to carry a GEM-handle containing a carboxy-terminal hexahistidine-tag and cysteine-tag. A two-step labeling strategy was optimized and applied to site-specifically label IRDye800CW and 99mTc to the sdAb. Bimodal labeling of the sdAbs proved straightforward and successful. 99mTc activity was however restricted to 18.5 MBq per nmol fluorescently-labeled sdAb to prevent radiobleaching of IRDye800CW without impeding SPECT/CT imaging. Subsequently, the in vivo biodistribution and tumor-targeting capacity of the bimodal tracer were evaluated in uPAR-positive tumor-bearing mice using SPECT/CT and fluorescence imaging. The bimodal sdAb showed expected renal background signals due to tracer clearance, along with slightly elevated non-specific liver signals. Four hours post-injection, both SPECT/CT and fluorescent images achieved satisfactory tumor uptake and contrast, with significantly higher values observed for the anti-uPAR bimodal sdAb compared to a control non-targeting sdAb. In conclusion, the GEM-handle is a convenient method for designing and producing bimodal sdAb-based tracers with adequate in vivo characteristics.

From lab to technical scale: Ultraviolet C treatment for the reduction of Lactococcus lactis bacteriophage P008 in whey

UV–C irradiation is a powerful non-thermal principle to inactivate lactococcal bacteriophages, which pose a high risk for fermentation failures in dairies. However, milk products limit ray penetration with their turbidity and absorption properties. In reactor design, attention must be paid to uniform and effective dose distribution, which can be achieved by thin fluid layers and/or turbulence. Preliminary tests performed in a lab-scale batch mode irradiation chamber showed filtered whey to be the most suitable application site. In a subsequent larger-scale feasibility study, two continuous flow-through reactors (lab-scale and technical-scale) were investigated. A bacteriophage reduction of 5 log units required a volume-related UV–C dose of 10.6 J mL−1 in the irradiation chamber, but only 1.8 J mL−1 in the continuous lab-scale reactor and 2.4 J mL−1 in the continuous technical-scale reactor. These data show that upscaling is feasible and that an effective bacteriophage inactivation with gentle product treatment is allowed.

Shielding Properties of Al- Cu- Pb Alloys by XCOM and Experimental Data

The current study, the efficiency of many binary and triple aluminum alloys was examined for the alloy’s samples consisting of (Al-Cu-Pb). These alloys were manufactured in the laboratories of the physics Department and the manufacture of melting furnaces as well as the design of casting molds, and then we used the gamma ray penetration technique to study the behavior of radiation attenuation by the manufactured alloys. The shielding properties of the prepared samples include mass attenuation coefficient ( ), radiation protection efficiency (RPE), half-value layer (HVL), and mean free path (MFP), Which were calculated theoretically using XCOM software. Experimental measurements were made at 60Co (1173, 1332 keV) 137Cs (662 keV) using a Gama spectrometer, which it contains the NaI (Tl) detector. It found that there is a good agreement between the experimental and theoretical values.

Investigation of the limitations and applicability of the method of homogeneous functions for solving the inverse kinematic problem of seismic exploration

The results of the application of the variational ray tracing algorithm to study the possibilities and limitations of one of the methods for solving the inverse kinematic problem of seismic exploration — the method of homogeneous functions developed at the Department of Seismometry and Geoacoustics of Moscow State University are presented. As a result of the calculations carried out on synthetic models and field material, conclusions were drawn about the exploration possibilities and areas of application of the method of homogeneous functions. Model examples show that the method of homogeneous functions gives correct results only for simple media: vertically inhomogeneous or layered with slightly inclined boundaries, and folds or inclusions can be restored only at a qualitative level. When working with real field data, the method of homogeneous functions correctly restores the velocity structure of the section to a depth of 1/3-1/2 of the maximum depth of ray penetration. At the same time, it makes sense to interpret only large anomalies with contrasting velocity values on the obtained velocity sections.

Magnetically regulated collapse in the B335 protostar?

Context. Whether or not magnetic fields play a key role in dynamically shaping the products of the star formation process is still largely debated. For example, in magnetized protostellar formation models, magnetic braking plays a major role in the regulation of the angular momentum transported from large envelope scales to the inner envelope, and is expected to be responsible for the resulting protostellar disk sizes. However, non-ideal magnetohydrodynamic effects that rule the coupling of the magnetic field to the gas also depend heavily on the local physical conditions, such as the ionization fraction of the gas. Aims. The purpose of this work is to observationally characterize the level of ionization of the gas at small envelope radii and to investigate its relation to the efficiency of the coupling between the star-forming gas and the magnetic field in the Class 0 protostar B335. Methods. We obtained molecular line emission maps of B335 with ALMA, which we use to measure the deuteration fraction of the gas, RD, its ionization fraction, χe, and the cosmic-ray ionization rate, ζCR, at envelope radii ≲1000 au. Results. We find large fractions of ionized gas, χe ≃ 1–8 × 10−6. Our observations also reveal an enhanced ionization that increases at small envelope radii, reaching values up to ζCR ≃ 10−14 s−1 at a few hundred astronomical units (au) from the central protostellar object. We show that this extreme ζCR can be attributed to the presence of cosmic rays accelerated close to the protostar. Conclusions. We report the first resolved map of ζCR at scales ≲1000 au in a solar-type Class 0 protostar, finding remarkably high values. Our observations suggest that local acceleration of cosmic rays, and not the penetration of interstellar Galactic cosmic rays, may be responsible for the gas ionization in the inner envelope, potentially down to disk-forming scales. If confirmed, our findings imply that protostellar disk properties may also be determined by local processes that set the coupling between the gas and the magnetic field, and not only by the amount of angular momentum available at large envelope scales and the magnetic field strength in protostellar cores. We stress that the gas ionization we find in B335 significantly stands out from the typical values routinely used in state-of-the-art models of protostellar formation and evolution. If the local processes of ionization uncovered in B335 are prototypical to low-mass protostars, our results call for a revision of the treatment of ionizing processes in magnetized models for star and disk formation.

Calculation of Spatial Response of a Collimated Segmented HPGe Detector for Gamma Emission Tomography by MCNP Simulations

We have proposed a planar electronically segmented high-purity germanium (HPGe) detector concept in combination with a multislit collimator for gamma emission tomography. In this work, the spatial resolution achievable using the collimated segmented HPGe detector was evaluated, prior to the manufacture and operation of the detector. The spatial response of a collimated segmented HPGe detector concept was evaluated using simulations performed with Monte Carlo N-Particle (MCNP) transport code MCNP6. The full detector and multislit collimator system were modeled, and for the quantification of the spatial response, the modulation transfer function (MTF) was chosen as a performance metric. The MTF curve was obtained through the calculation of the line spread function (LSF) by analyzing the simulated projection data. In addition, tomographic reconstructions of the simulated simplified test objects were made to demonstrate the performance of the segmented HPGe detector in planned application. For 662-keV photons, the spatial resolution obtained was approximately the same as the collimator slit width for both the 100- and 150-mm-long collimators. The corresponding spatial resolution at 1596-keV photon energy was almost twice the slit width for the 100-mm collimator, due to the partial penetration of the high-energy gamma rays through the collimator bulk. For a 150-mm-long collimator, an improved resolution was obtained.

FORMULATION OF SOLAR CREAM EXTRACT ETHANOL GANGGANG GREEN (Ulva lactuca L.) AND IN VITRO TEST OF SPF VALUE (SUN PROTECTING FACTOR)

<p>Excessive ultraviolet radiation or UV rays will make the epidermal tissue in the skin unable to resist the harmful effects. Sunscreen is a cosmetic ingredient that functions as a physical or chemical function as a barrier to the penetration of UV rays into the skin. Plants that can function as sunscreens because they have phenolic compounds, one of which is green algae (<em>Ulva lactuca</em> L).</p><p>This type of research is an experimental study using UV-Vis spectrophotometry to determine the ability of sun cream to inhibit UV radiation to the skin. The purpose of this study was to formulate sunscreen cream from ethanol extract of green algae (<em>Ulva lactuca</em> L.) and measure the best SPF (<em>Sun Protecting Factor</em>) value of various concentrations of green algae (Ulva lactuca L.) ethanol extract sunscreen cream.</p><p>The results of the study the SPF value of formula 1 (cream base) was 1.5077, which means formula 1 has no activity as sunscreen, formula 2 (3% green algae extract) with formula 2 (3% extract extract) with an SPF value of 7,311 which is classified as in the extra protection category, formula 3 (4% extract concentration) has an SPF value of 13,427 which is included in the maximum protection category and formula 4 with an SPF value of 19,282 which belongs to the ultra protection category. The cream formulation with the highest SPF value was formula 4. The higher the extract concentration, the higher the SPF value.</p>

Manufacture Shield from nano-rubber composite to protection from X-ray radiation

prepared The compound rubber material by reinforcing it with nanoparticle powder (N Pb) for protective shields in hospital X-ray units for the purpose of protecting fetuses from congenital deformity in pregnant women and workers in X-ray rays. The addition of chlorophyll extracted from tree leaves and plants as a plasticizer and anti-oxidant with different ratios of (20 - 100 pphr) and (20 pphr) was chosen as a percentage that achieves the purpose, but prevented it from penetrating the X-ray radiation is very little even at high ratios, as well as TiO_2 of (20 - 100 pphr) was added. 20 as a micro-filler for the purpose of obtaining good mechanical properties such as tensile strength, elasticity and hardness with different ratios (20 -100 pphr). 20 pphr was chosen as a ratio that achieves the purpose, but it prevents it from penetrating the X-ray rays. Very few even at high ratios. And by adding nanoparticles lead (40 – 350 pphr) good results in cutting the radiation penetrate the X-ray and the best ratios (100, 200, 300, 350 pphr) as adding (100 pphr) of N Pb to the rubber with a thickness (2 mm) the rays were penetrated and cut at (60 KV). Whereas, adding (200 pphr) of N Pb to the rubber with a thickness of (2 mm) prevented the penetration of X-Ray rays and cut them at (80 KV). Whereas, adding (300 pphr) of N Pb to the rubber with a thickness of (mm3) prevented the penetration of X-ray rays and cut them at (100KV). Whereas, adding (350 pphr) of N Pb to the rubber with a thickness of (3 mm) prevented the penetration of X-Ray rays and cut them at (110KV). In this way, the purpose of protecting the fetuses of pregnant women when they are exposed to radiation in the X-Ray units and their workers when using this material as a cover or shield with a thickness of (3 mm) was achieved.

A quantitative study on the effects of external geomagnetic fields by using the GeoMagSphere back-tracing code

Evaluation of cosmic ray trajectories and penetration inside the Earth environment is mandatory for estimation of flux by on-orbit detectors as well as of radiation damage on electronics devices and biological tissues, like those of astronauts onboard the International Space Station. We studied the impact of the external magnetic field on the calculation of some parameters like the rigidity cut-off, by a quantitative comparison among several geomagnetic field models. For this purpose we used GeoMagSphere back-tracing code, performing the particle trajectory reconstruction back-in-time from the chosen position and time up to the borders of the magnetosphere. The analysis done points out the need to combine an external magnetic field model with the internal one (usually IGRF). Several external field models have a different impact on the accuracy as well as on the time needed for calculation, important in case of a large amount of back-traced particles. We also studied cosmic ray propagation inside the magnetosphere, separately for quiet and disturbed solar activity periods. We found that during highly disturbed periods and during magnetic storms, rigidity cut-off, as well as cosmic ray flux, can be appropriately evaluated only by using external field models, like that one proposed by Tsyganenko and Sitnov (2005), well describing those particular conditions.

Gamma-ray induced photo emission from GaN single crystal wafer

Gamma-ray-induced photoemissions from GaN are investigated for as-grown and gamma-ray-irradiated single crystal wafers at room temperature. The GaN crystals are irradiated with gamma rays of 1.17 and 1.33 MeV from a cobalt-60 source. The gamma-ray-induced photoemission is analyzed by a spectroscope using the optical fiber cable placed in front of GaN. In the gamma-ray-induced photoemission from as-grown GaN wafers, the yellow luminescence (YL) is observed with a peak at around 600 nm in the spectrum around 440 nm–900 nm. The main YL peak is attributed to the Ga vacancy. The emission intensity increases almost in proportion to the wafer thickness when the thickness of the single crystal wafer increases from 0.25 mm to 0.75 mm due to the strong penetration of gamma rays in the crystal. In He–Cd laser excitation, the emission intensity does not depend on the thickness of the sample because the penetration of He–Cd laser light is near the surface. On the other hand, a gamma-ray-induced photoemission from GaN irradiated with a total gamma-ray dose of 990 kGy is observed with a peak at around 700 nm in the spectrum around 450 nm to 850 nm. The energy of the emission peak is close to the transition energy (1.83 eV) from the +1 state to the +2 state of the Ga interstitial. The gamma-ray-induced photoemission from GaN at room temperature suggests the possibility of GaN single crystal wafers to be used as a gamma-ray detector.

Investigation of laser-powder interaction in laser powder bed fusion process in additive manufacturing

Laser powder bed fusion (LPBF) is one of the most promising additive manufacturing (AM) technologies to fabricate metal components using laser beams. To understand the underlying thermal and physical phenomena in LPBF process, discrete element method (DEM) is applied to generate the randomly packed powder, then computational fluid dynamics (CFD) coupled with volume of fluid (VOF) is adopted to simulate the laser-powder interaction. The penetration and multiple reflection of laser rays is traced. The physics of melting and solidification is captured. The temperature profile indicates the laser travel path and the adsorption and transmission of laser rays with the powder. The wetting behaviour of the melt pool driven by the capillary forces leads to the formation of pores at the connection zone. It has been demonstrated that the developed model can capture the laser-powder interaction for further understanding of LPBF process.

The Galactic cosmic ray intensity at the evolving Earth and young exoplanets

ABSTRACT Cosmic rays may have contributed to the start of life on the Earth. Here, we investigate the evolution of the Galactic cosmic ray spectrum at the Earth from ages t = 0.6−6.0 Gyr. We use a 1D cosmic ray transport model and a 1.5D stellar wind model to derive the evolving wind properties of a solar-type star. At $t=1\,$ Gyr, approximately when life is thought to have begun on the Earth, we find that the intensity of ∼GeV Galactic cosmic rays would have been ∼10 times smaller than the present-day value. At lower kinetic energies, Galactic cosmic ray modulation would have been even more severe. More generally, we find that the differential intensity of low-energy Galactic cosmic rays decreases at younger ages and is well described by a broken power law in solar rotation rate. We provide an analytic formula of our Galactic cosmic ray spectra at the Earth’s orbit for different ages. Our model is also applicable to other solar-type stars with exoplanets orbiting at different radii. Specifically, we use our Galactic cosmic ray spectrum at 20 au for $t=600\,$ Myr to estimate the penetration of cosmic rays in the atmosphere of HR 2562b, a directly imaged exoplanet orbiting a young solar-type star. We find that the majority of particles <0.1 GeV are attenuated at pressures ≳10−5 bar and thus do not reach altitudes below ∼100 km. Observationally constraining the Galactic cosmic ray spectrum in the atmosphere of a warm Jupiter would in turn help constrain the flux of cosmic rays reaching young Earth-like exoplanets.

Resistance against Penetration of Electromagnetic Radiation for Ultra-light Cu/Ni-Coated Polyester Fibrous Materials.

Resistance against penetration of various rays including electromagnetic waves (EM), infrared rays (IR), and ultraviolet rays (UV) has been realized by using copper (Cu)-coated fabrics. However, the corrosion of the Cu on coated fabrics influenced the shielding effectiveness of the various rays. Besides, the metal-coated fabrics have high density and are unbreathable. This work aims to solve the problem by incorporating nickel (Ni) into the Cu coating on the ultra-light polyester fibrous materials (Milife® composite nonwoven fabric—10 g/m2, abbreviation Milife) via electroless plating. The electromagnetic interference (EMI), IR test, ultraviolet protection factor (UPF), water contact angle, and air permeability of the Cu/Ni-coated Milife fabric were measured. All the samples were assumed as ultra-light and breathable by obtaining the similar fabric density (~10.57 g/m2) and large air permeability (600–1050 mm/s). The Cu/Ni deposition on the Milife fabrics only covered the fibers. The EM shielding effectiveness (SE) decreased from 26 to 20 dB, the IR reflectance (Rinfrared) decreased from 0.570 to 0.473 with increasing wNi from 0 to 19.5 wt %, while the wNi improved the UPF from 9 to 48. Besides, addition of Ni changed the Cu/Ni-coated Milife fabric from hydrophilicity to the hydrophobicity by observing WCA from 77.7° to 114°.

An Interstellar Synthesis of Glycerol Phosphates

Abstract Glycerol phosphates define key molecules pertaining to the Origin of Life question and represent the essential stereo-dictating unit of phospholipids that may self-assemble in aqueous media into prebiotic cell membranes. However, the prebiotic formation pathways to glycerol phosphate have remained elusive to date. In this Letter, we expose a facile pathway toward the abiotic synthesis of glycerol phosphate isomers in phosphine (PH3) doped interstellar analog ices of methanol (CH3OH), carbon dioxide (CO2), or water (H2O) upon exposure to energetic electrons as a proxy of secondary electrons generated by the penetration of Galactic cosmic rays into interstellar ices at 10 K. The synthetic routes proposed here overcome obstacles of terrestrial-based scenarios that are inhibited by the low solubility of phosphates in water and the unfavorable nature of phosphorylation reactions in aqueous solution, thus revealing a potential pathway to prebiotic glycerol phosphates.

Muography for geological hazard assessment in the South Aegean active volcanic arc (SAAVA)

This article reviews the suitability of muography in identifying geological hazards in the southern Aegean active volcanic arc (SAAVA). Santorini and Nisyros, the most active members of SAAVA, exhibit critical structural failures which are controlled by the regional tectonic stress field. Comparable structural failures in other volcanic complexes (e.g. Canary Islands, Hawaii, Stromboli, etc.) are linked to high geological risk. However, the amount of hazard stemming from potential rupture of volcanoes in the Aegean Sea has not been fully assessed yet, because the volcanoes’ intricate structure challenges both conventional geological and geophysical mapping. On the other hand, muography constitutes a novel remote sensing technique which exploits the penetration of the cosmic rays in the upper solid earth to produce images of the upper solid earth at high spatial resolution. Here, the performance of muography in identifying geological hazards in the SAAVA is evaluated on the basis of available geological information and similar case studies with satisfactory results.

Characteristics of the Short-Period S-Wave Attenuation Field in the Source Zone of the Strongest Tohoku Earthquake of March 11, 2011 (Mw = 9.0)

The characteristics of the short-period S-wave attenuation field in the source zone of the strongest Tohoku earthquake of March 11, 2011 in the northeast of Japan are considered (Mw = 9.0). The records of shallow local earthquakes obtained by the MAJO station at distances of 250 to 700 km are processed. A method based on the analysis of the ratio of the maximum amplitudes of the Sn and Pn waves (the Sn/Pn parameter) is used. The source zone is divided into four regions bounded by coordinates 36°–37°, 37°–38°, 38°–39°, and 39°–40°18′ N; and 140°30ʹ–145° E. It is established that all the regions contain segments of a rapid decrease in the Sn/Pn values, which are followed by segments of their sharp growth at small epicentral distances in all the areas. Another segment of rapid decrease in the Sn/Pn parameter is identified in all regions at relatively large distances. It is assumed that the first segments of rapid decrease in the Sn/Pn values are related to the gradual sinking of the S-wave rays in the mantle wedge. In this case, the minimum values of the parameter correspond to rays partly moving along the foot of this wedge. Such an effect is explained by the fact that the biggest content of the deep-seated fluids ascending due to the dehydration of the oceanic crust rocks correspond to the bottom of the mantle wedge. The segments of a sharp increase in the Sn/Pn values are likely to correspond to the propagation of rays within the upper part of the plate characterized by very weak attenuation. The second segments of the rapid decrease in the Sn/Pn parameter are related to the ray penetration into the waveguide formed in the bottom part of the plate formed as a result of the dehydration of the mantle rocks. The mean values Sn/Pn(Δ) in the four areas are much lower than in the source zone of the strongest Maule earthquake of February 27, 2010 (Chile, Mw = 8.8). This effect agrees with the earlier assumption about the larger fluid content in the subduction zones in the west of the Pacific Ocean compared to the east. Furthermore, this allows us to explain the features of the aftershock processes in these two enormous regions of the Pacific Ring.