keV Source Research Articles

Deep learning based x-ray spectrometer for high repetition rate characterization of betatron radiation

Betatron radiation produced from a laser-wakefield accelerator is a broadband, hard x-ray (>1 keV) source that has been used in a variety of applications in medicine, engineering, and fundamental science. Further development and optimization of stable, high repetition rate (HRR) (>1 Hz) betatron sources will provide a means to extend their application base to include single-shot dynamical measurements of ultrafast processes or dense materials. Recent advances in laser technology used in such experiments have enabled increases in shot-rate and system stability, providing improved statistical analysis and detailed parameter scans. However, unique challenges exist at high repetition rate, where data throughput and source optimization are now limited by diagnostic acquisition rates and analysis. Here, we present the development of a machine-learning algorithm for the real-time analysis of betatron radiation. We report on the fielding of this deep learning algorithm for online source characterization at the Institut National de la Recherche Scientifique's Advanced Laser Light Source. By fine-tuning an algorithm originally trained on a fully synthetic dataset using a subset of experimental data, the algorithm can predict the betatron critical energy with a percent error of 7.2 % with a reconstruction time of 1.5 ms, providing a valuable tool for real-time, multi-objective optimization at HRR.

Low-luminosity accretion of Be/X-ray pulsar MAXI J1409−619

ABSTRACT This paper used Nuclear Spectroscopic Telescope Array observations to examine the temporal and spectral features of the Be/X-ray binary pulsar MAXI J1409−619. The timing analysis of the light curve finds the pulsation of the source at $(501.23\,\,\pm \,\,0.01)$ s. The pulse profile of the source in various energy bands was analysed and showed weak dependence on energy exhibiting asymmetric character and generally suggests a source accretion in the subcritical regime. The variation of pulse fraction with photon energy in general shows an increasing trend. Assuming a distance of 14.5 kpc, we calculated the 3–30 keV source luminosity to be $\sim 6.13\,\,\times \,\,10^{34}\,\,$ erg s$^{-1}$. The long-term spin evolution of the source was carried out, where the source underwent torque reversal.

High performance fluoroelastomer composites filled with graphite and/or bismuth oxide for applications in gamma‐ray shielding

AbstractFluoroelastomer‐based composites with nano‐sized bismuth oxide (B) and/or graphite (G) as fillers were prepared and characterized using FKM type 1 fluoroelastomer as a matrix. The effects of these fillers used singly or in combination on the crosslinking process, mechanical, thermal, dynamic mechanical, electrical, optical, and high‐energy radiation attenuation properties of FKM were investigated. The results showed that graphite significantly increased the moduli E50 (MPa) of FKM/G and FKM/GB composites by 1026% and 1459%, respectively, compared to FKM. On the other hand, bismuth(III) oxide did not affect the stiffness or elongation at break of FKM significantly. Graphite also imparted electrical conductivity to FKM (10−6 Scm−1), which was reduced by bismuth oxide to 10−12 Scm−1. Furthermore, the linear attenuation coefficients (μ), half‐value layer (HVL), and tenth‐value layer (THV) of pure FKM and FKM composites were evaluated using a 137Cs (662 keV) source, revealing that FKM/B and FKM/GB composites show 47.4% and 35.8% higher μ values, respectively, than FKM. Taking into consideration that the attenuation coefficient of FKM is 10 times higher than conventional elastomers such as natural rubber, these results indicate that thin flexible shielding against high electromagnetic radiation can be achieved to protect different sensitive equipment such as electronic devices used in nuclear power plants, gamma radiation facilities, telescopes, and artificial satellites.Highlights A fluoroelastomer‐based composite containing 40 phr of bismuth(III) oxide nanopowder presents a gamma attenuation coefficient 47.4% higher than that of the polymer matrix. A fluoroelastomer‐based composite containing bismuth(III) presents a band gap of 2.40 eV. Bismuth(III) oxide nanopowder hinders the electrical conductivity imparted by a conducting filler contained in the fluoroelastomer‐based composite. Fluoroelastomer‐based composites containing graphite or bismuth(III) oxide present enhanced mechanical and thermal properties.

Relativistic X-ray reflection and highly ionized absorption in the spectrum of NS LMXB 1A 1744−361

ABSTRACT We present the results from the spectral and timing analysis of the accreting neutron star (NS) 1A 1744−361 from the Nuclear Spectroscopic Telescope ARray observation performed in its 2022 outbursts. The unabsorbed bolometric X-ray luminosity during this observation in the energy band 0.1–100 keV is 3.9 × 1037 erg s−1, assuming a distance of 9 kpc. During this observation, the source was in the banana branch of the atoll track. The source spectrum exhibits relativistic disc reflection and clear absorption features when an absorbed blackbody and cut-off power-law model describes the continuum emission. The 3–50 keV source spectrum is well fitted using a model combination consisting of an absorbed single-temperature blackbody and a reflection model along with the addition of a warm absorber component. The inner-disc radius, Rin, obtained from the reflection fit is ∼(1.61–2.86)RISCO = (8.4–14.9)Rg (17.6–31.2 km for a 1.4 M⊙ NS). This measurement allowed us to further constrain the magnetic field strength to B ≲ 0.94 × 109 G. The strong absorption features ∼6.91 keV and ∼7.99 keV imply the presence of highly ionized absorbing material with a column density NH of ∼3 × 1022 cm−2, emanating from the accretion disc in the form of disc wind with an outflow velocity of vout ≃ 0.021c ≃ 6300 km s−1.

Investigating the effect of H+-ion irradiation on layered α-MoO3 flakes by defect engineering

Ion irradiation is a versatile and convenient tool for modifying the optical, electrical, and catalytic properties of two-dimensional (2D) materials through controlled induction of impurities and defects. The behavior of 2D materials under ion irradiation is interesting, which needs to be explored in the contest of their optoelectronic applications. In the present work, we have reported the effect of H+-ion irradiation on layered α-MoO3 flakes by defect engineering. Initially, the α-MoO3 crystals were synthesized using the physical vapor deposition technique followed by mechanical exfoliation of an as-grown crystal to obtain α-MoO3 flakes of different thicknesses. Then, the exfoliated flakes were exposed to H+-ion/proton irradiation with a fluence of 1 × 1016 ions/cm2 using a 30 keV source. After irradiation, new photoluminescence (PL) emission peaks were observed at different positions in the range of ∼2.4–1.9 eV, which was found to be absent in pristine flakes. Raman studies revealed non-uniform oxygen vacancy distribution in H+-ion irradiated α-MoO3 flakes, which affected the PL peak positions. Additionally, first-principle calculations and Bader charge analysis were performed to identify the origin of the new PL peaks. Our findings indicate that oxygen vacancies positioning at different locations of the α-MoO3 lead to the emergence of new absorption peaks within the range of ∼2.2–1.25 eV, which is consistent with our experimental findings. The present study gives insight into exploring the use of ion-irradiated α-MoO3 in optoelectronics applications with tunable properties.

Effect of heavy-weight recycled materials on radiation shielding and properties of high-strength concrete with CEM III

This research aims to study the effect of replacing up to 100% of recycled coarse aggregates with heavyweight aggregates. In addition to the effect of adding heavyweight aggregate slag on the efficiency of shielding against radiation and on the mechanical physical properties and elevated temperature of heavyweight high-strength concrete (HWHSC). In this investigation, HWHSC mixtures incorporate lead slag (LS), copper slag (CS), and steel slag (SS) as coarse aggregate. Recycled heavyweight coarse aggregates are added to concrete mixtures at volume ratios of 0%, 25%, 50%, 75%, and 100%. Slump test, compressive strength, flexural strength, tensile strength, elastic modulus, and bulk density tests were carried out. Three different gamma-ray energies at 137Cs 662, 60Co 1173, and 60Co 1332 (keV) sources were used to evaluate the mass attenuation coefficient, linear attenuation coefficient, half and tenth-value layer, and mean free path. To evaluate the impact of elevated temperature on density, compressive strength, and radiation shielding properties, concrete mixtures were exposed to 22 °C, 300 °C, 500 °C, and 800 °C. Compared to basalt-based concrete, heavy-weight concrete (HWC) incorporating LS, CS, and SS coarse aggregate has a significantly higher density. The results show a good effect of recycled heavyweight coarse aggregates on fresh, mechanical, and radiation-shielding properties. The density of the developed high-strength concrete (HSC) mixes ranges between 2400 and 3370 kg/m3, and the increase in recycled heavyweight coarse aggregates replacement ratio up to 75% increased all mechanical characteristics of HWC mixtures. Using LS as a replacement of basalt by 75% resulted in the highest compressive strength, splitting tensile strength, flexural strength, and elastic modulus of 105.8 MPa, 14.2 MPa, 19.5 MPa, and 45.76 GPa, respectively. Compared to basalt, LS, CS, and SS eliminate the impact of elevated temperatures on HSHWC strength. The best radiation protection properties were achieved with the complete replacement of basalt by LS.

Small-sized bright point-like source of picosecond soft x-ray pulses based on a high-voltage vacuum discharge

A small-sized soft x-ray (energy ≤ 1 keV) source based on a high-voltage vacuum discharge with a current of 20 kA and an ultrashort pulse duration of about 10 ps has been developed. It was shown that the radiation was emitted by a micropinch, which was formed in the discharge plasma and had a size of the order of a micrometer. In a single shot, an image of the test object was obtained with a resolution of several micrometers.

Multiscale Monte Carlo simulations of gold nanoparticle dose-enhanced radiotherapy II. Cellular dose enhancement within macroscopic tumor models.

Gold NanoParticle (GNP) dose-enhanced radiation therapy (GNPT) requires consideration of physics across macro- to microscopic length scales, however, this presents computational challenges that have limited previousinvestigations. To develop and apply multiscale Monte Carlo (MC) simulations to assess variations in nucleus and cytoplasm dose enhancement factors (n,cDEFs) over tumor-scalevolumes. The intrinsic variation of n,cDEFs (due to fluctuations in local gold concentration and cell/nucleus size variation) are estimated via MC modeling of varied cellular GNP uptake and cell/nucleus sizes. Then, the Heterogeneous MultiScale (HetMS) model is implemented in MC simulations by combining detailed models of populations of cells containing GNPs within simplified macroscopic tissue models to evaluate n,cDEFs. Simulations of tumors with spatially uniform gold concentrations (5, 10, or 20mgAu /gtissue ) and spatially varying gold concentrations eluted from a point are performed to determine n,cDEFs as a function of distance from the source for 10 to 370 keV photons. All simulations are performed for three different intracellular GNP configurations: GNPs distributed on the surface of the nucleus (perinuclear) and GNPs packed into one or four endosome(s). Intrinsic variations in n,cDEFs can be substantial, for example, if GNP uptake and cell/nucleus radii are varied by 20%, variations of up to 52% in nDEF and 25% in cDEF are observed compared to the nominal values for uniform cell/nucleus size and GNP concentration. In HetMS models of macroscopic tumors, subunity n,cDEFs (i.e., dose decreases) can occur for low energies and high gold concentrations due to attenuation of primary photons through the gold-filled volumes, for example, n,cDEF<1 is observed 3mm from a 20 keV source for the four endosome configuration. In HetMS simulations of tumors with spatially uniform gold concentrations, n,cDEFs decrease with depth into the tumor as photons are attenuated, with relative differences between GNP models remaining approximately constant with depth in the tumor. Similar initial n,cDEF decreases with radius are seen in the tumors with spatially varying gold concentrations, but the n,cDEFs for all of the GNP configurations converge to a single value for each energy as gold concentration reacheszero. The HetMS framework has been implemented for multiscale MC simulations of GNPT to compute n,cDEFs over tumor-scale volumes, with results demonstrating that cellular doses are highly sensitive to cell/nucleus size, GNP intracellular distribution, gold concentration, and cell position in tumor. This work demonstrates the importance of proper choice of computational model when simulating GNPT scenarios and the need to account for intrinsic variations in n,cDEFs due to variations in cell/nucleus size and goldconcentration.

An extensive investigation on gamma shielding properties of PLA/Gd2O3 nanocomposites

This paper presents the gamma shielding performance of Poly lactic acid (PLA) composites doped with 4%, 8%, 12%, and 16% Gd2O3 to investigate the impact of dopant amount on gamma shielding with an energy of 241Am (59.5 keV), 133Ba (81.0, 276.4, 302.9, 356.0, 383.9 keV), 22Na (511.0,1274.5 keV), 137Cs (661.7 keV), and 60Co (1173.2, 1332.5 keV) sources. To characterize the radiation shielding properties of the samples, mass attenuation coefficient (μ/ρ), linear attenuation coefficient (μ), half-value layer (HVL), tenth-value layer (TVL), and effective atomic number (Zeff) parameters were calculated and compared with the values computed by WinXCOM software. It is revealed that theoretical and experimental results are in agreement and the radiation protection efficiency was enhanced with the increase of the dopant amount. Radiation effects on the structure and thermal stability of the samples were also studied by Attenuated total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) measurements and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The spectroscopy results showed a remarkable decrease in the absorbance value of the composites after gamma irradiation.

Multiwavelength studies of G298.6−0.0: An old GeV supernova remnant interacting with molecular clouds

Abstract Hadronic γ-ray sources associated with supernova remnants (SNRs) can serve as stopwatches for the escape of cosmic rays from SNRs, which gradually develops from highest-energy particles to lowest-energy particles with time. In this work, we analyze the 13.7 yr Fermi-LAT data to investigate the γ-ray feature in/around the SNR G298.6−0.0 region. With γ-ray spatial analyses, we detect three point-like components. Among them, Src-NE is at the eastern SNR shell, and Src-NW is adjacent to the western edge of this SNR. Src-NE and Src-NW demonstrate spectral breaks at energies around/below 1.8 GeV, suggesting an old SNR age of &amp;gt;10 kyr. We also look into the X-ray emission from the G298.6−0.0 region, with the Chandra-ACIS data. We detected an extended keV source having a centrally filled structure inside the radio shell. The X-ray spectra are well fitted by a model which assumes a collisional ionization equilibrium of the thermal plasma, further supporting an old SNR age. Based on our analyses of the NANTEN CO- and ATCA-Parkes H i-line data, we determined a kinematic distance of ∼10.1 kpc from us to G298.6−0.0. This distance entails a large physical radius of the SNR of ∼15.5 pc, which is additional evidence for an old age of &amp;gt;10 kyr. Besides this, the CO data cube enables us to three-dimensionally locate the molecular clouds (MCs) which are potentially interacting with SNR G298.6−0.0 and could account for the hadronic γ-rays detected at Src-NE or Src-NW. Furthermore, the multiwavelength observational properties unanimously imply that the SNR–MC interaction occurs mainly in the north-eastern direction.

Diffraction enhanced imaging utilizing a laser produced x-ray source.

Image formation by Fresnel diffraction utilizes both absorption and phase-contrast to measure electron density profiles. The low spatial and spectral coherence requirements allow the technique to be performed with a laser-produced x-ray source coupled with a narrow slit. This makes it an excellent candidate for probing interfaces between materials at extreme conditions, which can only be generated at large-scale laser or pulsed power facilities. Here, we present the results from a proof-of-principle experiment demonstrating an effective ∼2 μm laser-generated source at the OMEGA Laser Facility. This was achieved using slits of 1 ×30μm2 and 2 ×40μm2 geometry, which were milled into 30 μm thick Ta plates. Combining these slits with a vanadium He-like 5.2keV source created a 1D imaging system capable of micrometer-scale resolution. The principal obstacles to achieving an effective 1 μm source are the slit tilt and taper-where the use of a tapered slit is necessary to increase the alignment tolerance. We demonstrate an effective source size by imaging a 2 ± 0.2 μm radius tungsten wire.

Flexible gamma ray shielding based on natural Rubber/BaSO4 nanocomposites

This study aims to fabricate lead-free, flexible gamma ray shielding based on natural rubber (NR) with the original-sized barium sulphate (BaSO4) and BaSO4 nanocomposites. The shielding composites were successfully fabricated with various fillers loading of 10, 20, 30 and 50 parts per hundred rubbers (phr). The physical and mechanical properties of the NR composites have been investigated. The gamma ray shielding properties were measured with 57Co (122.06 keV) and 133Ba (356.02 keV) sources. Our results indicated that additional filler concentrations into NR increased density, hardness (shore A), tensile modulus, tensile strength, and elongation at break of NR. Tensile properties and elongation at break of NR with BaSO4 nanoparticles were slightly lower than the ordinary-sized BaSO4. For the gamma ray shielding properties, the linear attenuation coefficient (μ) mass attenuation coefficient (μm) were increased with the increasing of fillers concentrations. The half value layer (HVL) was decreased with the increasing of BaSO4 and BaSO4 nanoparticles in NR. In comparison of shielding properties between NR with BaSO4 nanoparticles and the ordinary-sized BaSO4 showed that the NR with nanocomposites provided better gamma radiation shielding due to the large surface to volume area of nanocomposites. In conclusion, the novel developed shielding based on NR/BaSO4 nanocomposites showed a promising result for developing potential radiation shielding due to their flexibility, lightweight and lead-free shielding material.

Timing and spectral analysis of HMXB OAO 1657-415 with NuSTAR

ABSTRACT This work presents a comprehensive timing and spectral analysis of high-mass X-ray binary pulsar, OAO 1657-415 by using the observation made with Nuclear Spectroscopic Telescope Array on 2019 June. During this observation, OAO 1657-415 exhibited X-ray variability by a factor of about 3. X-ray pulsations at 37.03322(14) s were observed up to 70 keV. OAO 1657-415 was undergoing a spin-down phase with $\dot{P} = 9(1) \times 10^{-8}$ s s−1. This is an order of about 100 larger than the long-term spin-up rate. The pulse profile evolved marginally during the observation. We have discussed the long-term pulse period history of the source spanning a time-base of 43 yr, including the latest Fermi/GBM data. The 3–70 keV source spectrum is described by a partially covered cut-off power law, an Fe Kα line at 6.4 keV and a Compton shoulder at 6.3 keV. We report the presence of a cyclotron absorption feature around 40 keV, which is indicative of a surface magnetic field strength of 3.59 ± 0.06 (1 + $z$) × 1012 and $3.29_{-0.22}^{+0.23} \ (1 + z) \times 10^{12}$ G. This work shows the first robust presence of cyclotron absorption feature in the source.

Spectral and Timing Analysis of NuSTAR and Swift/XRT Observations of the X-Ray Transient MAXI J0637–430

Abstract We present results for the first observed outburst from the transient X-ray binary source MAXI J0637–430. This study is based on eight observations from the Nuclear Spectroscopic Telescope Array (NuSTAR) and six observations from the Neil Gehrels Swift Observatory X-Ray Telescope (Swift/XRT) collected from 2019 November 19 to 2020 April 26 as the 3–79 keV source flux declined from 8.2 × 10−10 to 1.4 × 10−12 erg cm−2 s−1. We see the source transition from a soft state with a strong disk-blackbody component to a hard state dominated by a power-law or thermal Comptonization component. NuSTAR provides the first reported coverage of MAXI J0637–430 above 10 keV, and these broadband spectra show that a two-component model does not provide an adequate description of the soft-state spectrum. As such, we test whether blackbody emission from the plunging region could explain the excess emission. As an alternative, we test a reflection model that includes a physical Comptonization continuum. Finally, we also test a spectral component based on reflection of a blackbody illumination spectrum, which can be interpreted as a simple approximation to the reflection produced by returning disk radiation due to the bending of light by the strong gravity of the black hole. We discuss the physical implications of each scenario and demonstrate the value of constraining the source distance.

Resolving Complex Inner X-Ray Structure of the Gravitationally Lensed AGN MG B2016+112

Abstract We use a Chandra X-ray observation of the gravitationally lensed system MG B2016+112 at z = 3.273 to elucidate the presence of at least two X-ray sources. We find that these sources are consistent with the very long baseline interferometry (VLBI) components measured by Spingola, which are separated by ∼200 pc. Their intrinsic 0.5–7 keV source frame luminosities are 1.5 × 1043 and 1.8 × 1044 erg s−1, respectively. Most likely this system contains a dual active galactic nucleus (AGN), but we are possibly detecting an AGN plus a parsec-scale X-ray jet, the latter lying in a region at very high magnification. The quadruply lensed X-ray source is within ±40 pc (1σ) of its VLBI counterpart. Using a gravitational lens as a telescope, and a novel statistical application, we have achieved unprecedented accuracy for measuring metric distances at such large redshifts in X-ray astronomy. This is tens of mas if the source is located close to the caustics, while it is of hundreds of mas if the source is in a region at lower amplification. The present demonstration of this approach has implications for future X-ray investigations of large numbers of lensed systems.

Study of radioactive particle tracking using MCNP-X code and artificial neural network

Agitators or mixers are highly used in the chemical, food, pharmaceutical and cosmetic industries. During the fabrication process, the equipment may fail and compromise the appropriate stirring or mixing procedure. Besides that, it is also important to determine the right point of homogeneity of the mixture. Thus, it is very important to have a diagnosis tool for these industrial units to assure the quality of the product and to keep the market competitiveness. The radioactive particle tracking (RPT) technique is widely used in the nuclear field. In this paper, a method based on the principles of RPT is presented. Counts obtained by an array of detectors properly positioned around the unit will be correlated to predict the instantaneous positions occupied by the radioactive particle by means of an appropriate mathematical search location algorithm. Detection geometry developed employs eight NaI(Tl) scintillator detectors and a Cs-137 (662 keV) source with isotropic emission of gamma-rays. The modeling of the detection system is performed using the Monte Carlo Method, by means of the MCNP-X code. In this work, a methodology is presented to predict the position of a radioactive particle to evaluate the performance of agitators in industrial units by means of an Artificial Neural Network.

Development of Composite Scintillators Based on the LuAG: Pr Single Crystalline Films and LuAG:Sc Single Crystals

The scintillation properties of novel type of composite scintillator based on Lu3Al5O12:Pr (LuAG:Pr) single crystalline film (SCF) and LuAG:Sc substrate grown by the liquid-phase epitaxy method are considered in this work. The registration of α-particles and γ-quanta in such types of composites occurs by means of separation of the scintillation decay kinetics of SCF and crystal parts, respectively. Namely, under excitation by α-particles of 241Am (5.5 MeV) source and γ-quanta of 137Cs (662 keV) source, the large differences in the respective scintillation decay kinetics and decay time values tα and tγ are observed for the LuAG:Pr SCF/LuAG:Sc SC composite scintillator with various film thicknesses. Furthermore, the best tγ/tα ratio above 4.5 is achieved for such types of epitaxial structure with SCF and substrate thicknesses of 17 μm and about 0.5 mm, respectively. The development types of composite scintillators can be successfully applied for simultaneous registration of α-particles and γ-quanta in the mixed radiation fluxes.

Using Chandra Localizations and Gaia Distances and Proper Motions to Classify Hard X-Ray Sources Discovered by INTEGRAL

Abstract Here, we report on X-ray observations of ten 17–60 keV sources discovered by the International Gamma-Ray Astrophysics Laboratory satellite. The primary new information is sub-arcsecond positions obtained by the Chandra X-ray Observatory. In six cases (IGR J17040-4305, IGR J18017-3542, IGR J18112-2641, IGR J18434-0508, IGR J19504+3318, and IGR J20084+3221), a unique Chandra counterpart is identified with a high degree of certainty, and for five of these sources (all but J19504), Gaia distances or proper motions indicate that they are Galactic sources. For four of these, the most likely classifications are that the sources are magnetic cataclysmic variables (CVs). J20084 could be either a magnetic CV or a high-mass X-ray binary. We classify the sixth source (J19504) as a likely active galactic nucleus (AGN). In addition, we find likely Chandra counterparts to IGR J18010-3045 and IGR J19577+3339, and the latter is a bright radio source and probable AGN. The other two sources, IGR J12529-6351 and IGR J18013-3222, do not have likely Chandra counterparts, indicating that they are transient, highly variable, or highly absorbed.

Growth and optical caracteristics of the CsI:Li scintillator crystal for use as radiation detector

Materials capable of converting ionizing radiation into light photons are called scintillators, some have specific efficiencies for certain applications and types of radiation, e.g. gamma, X-ray, alpha, beta and neutrons. CsI:Tl and NaI:Tl crystals are commonly found in the market because they have several applications, but few studies have been done on lithium doped cesium iodide crystal (CsI:Li). The lithium element, in this crystal used as a dopant, is also exploited as a converter for neutron detection, as it has a shock section of 940 barns for thermal neutrons. The study of the CsI:Li crystal is convenient considering the natural abundance of the lithium element with 7.5%, besides the interest in having a low cost national scintillator material with an opportunity to search the response of a detector for different types of radiation. The CsI:Li crystal was grown with molar concentration 10-4 to 10-1, using the vertical Bridgman technique. The parameters involved in the growth process were investigated. The transmittance was evaluated in the spectral region from 190 nm to 1100 nm. Luminescence emission spectra for the CsI:Li crystal were evaluated by photometric analysis of the crystal stimulated with a 137Cs (662 keV) source in front of the coupled sample at the monochromator input. The crystals showed of maximum luminescence intensity at the wavelength of 420 nm. The response of the scintillators when excited with gamma radiation of 241Am, 133Ba, 22Na, 137Cs, 60Co and neutron radiation from the AmBe source, with energy range of 1 MeV to 12 Mev was evaluated.

Study of gamma radiation shielding efficiency with radiation-resistant Bi2O3-TeO2-WO3 ceramics

This paper presents the results of a study of the efficiency of shielding gamma radiation with an energy of Co57 (136 keV), Cs137 (661 keV), Na22 (1274 keV) source by Bi2O3-TeO2-WO3 ceramics. During the studies of the shielding efficiency, it was found that an increase in the thickness of ceramics to 0.3–0.4 mm leads to a sharp increase in the shielding efficiency up to 25–50% of radiation, while the shielding efficiency for ceramics with a thickness of 0.1–0.2 mm was no more than 3–9%. The peculiarity of this work from the already known ones is that the conditions of synthesis and subsequent thermal sintering, selected experimentally, make it possible to obtain ceramics with a stable Bi2Te2W3O16 phase, while in most works the samples under study are amorphous or amorphous-like structures.