Gamma-ray Sources Research Articles

Documents to procure gamma irradiation chamber and license for operation in blood center

Abstract: Graft-versus-host disease is a critical posttransplant complication, particularly affecting individuals with compromised immune systems. Patients undergoing bone marrow transplants, neonates receiving intrauterine transfusions, and those recipients of blood from first-degree relatives are vulnerable to this condition. The significance of efficient lymphocyte inactivation has driven the widespread adoption of Gamma Irradiation Chambers (GICs) utilizing radiation sources such as Cesium-137 (Cs-137) or Cobalt-60 (Co-60). However, the effective operation of these chambers is contingent on navigating a complex regulatory landscape (Cs-137 or Co-60 is commonly used as the source of gamma rays. The usual dose is 25 Gray [Gy] to 35 Gy [1 Gy = 100 rads], this dosage inactivates 85%–95% of lymphocytes in the blood components without any adverse effect on other cellular components of the blood). GIC unit mainly houses either Co-60 or Cs-137as radiation sources (model no BI-2000, BI-5000 mfr. by Board of Radiation and Isotope Technology with typical radioactivity ranging from tens to hundreds of terabecquerel. These units are also used in research institutions, hospitals, blood center, etc. A review of legal, regulatory, and policy aspects of the operation of GIC in India regarding its issues, challenges, and opportunities. We aimed to prepare a standard guidance document for GIC for a smooth process of the Atomic Energy Regulatory Board (AERB) licensing and equipment purchasing. The present article was written based on the experience of applying for GIC with AERB and recurrent support extended to colleagues in the fraternity. The documents prepared for licensing and various procedural steps involved in the same are included. Many documents and many days are required from procurement to the receipt of the license for operation GIC. At the same time, with very few user institutes and less number of experienced people in the country, it becomes difficult to find a proper method to approach the national government body. If blood center/radiological safety officer are properly trained as per the guidelines available, this can reduce man-days and facilitate the earliest operations.

Illumination of a Planet by a Black Hole Moon as a Technological Signature

I show that Hawking radiation from a mini black hole with a mass of ∼1011 g in a low orbit around an otherwise frozen rogue planet, can supply the energy needs of a civilization on the surface of the planet. Maintaining this furnace for more than a few years requires a modest accretion rate of ∼2 kg s−1. The associated technosignature is detectable as a gamma-ray source occulted by a warm planet every 1–2 hr, with no stellar-mass companion.

Determining the Position of Gamma-Ray Interaction Using Large Scintillation Detectors and the Least Number of Photomultiplier Tubes

Determining the position of interaction is of great interest for gamma-ray imaging in various nuclear applications. Among all gamma-ray detectors, scintillation detectors are commonly exploited for imaging purposes because they can be prepared in large dimensions and are economically affordable. In this work, the general shape of the measured gamma-ray spectra of two long and large-area plastic scintillation detectors are analyzed by artificial neural networks to determine the position of interaction in one and two dimensions (1D and 2D), respectively. The position of interaction was treated as the position of a 137Cs gamma-ray point source on the long and large-area scintillation detectors. Utilizing this method, only one photomultiplier tube (PMT) was used for 1D positioning of interaction in a 4 × 4 × 35-cm3 long plastic detector, while just two PMTs were applied for 2D positioning of interaction in a 50 × 50 × 5-cm3 large-area plastic detector. The position of interaction in the long detector was determined with a resolution of 1 cm and a mean absolute error of less than 1%, while a resolution of 5 cm with a mean absolute error of 13% was achieved for the large-area detector.

Evaluation of gamma rays shielding properties of bismuth tungstate with different morphologies

To develop lead-free gamma-ray shielding material, bismuth tungstate (Bi2WO6) nanocrystals were synthesized under different conditions of precursor solution by hydrothermal method and composite material based on polyurethane and bismuth tungstate nanocrystals were prepared and evaluated using gamma ray sources in this study. The effects of crystal structure and morphology on the gamma ray shielding properties of bismuth tungstate were specially investigated. Results indicated that pH value of precursors solution had significant effect on the synthesis of bismuth tungstate: orthorhombic Bi2WO6 were obtained under acidic or neutral conditions while tetragonal Bi0.875W0.125O1.6875 were obtained under strongly alkaline condition. With the increase of pH value, the morphology of bismuth tungstate changed from flower-like microspheres to persimmon-like microstructures, and then to randomly stacked nanosheets. Bismuth tungstate nanocrystals were added to polyurethane to prepare flexible gamma-ray shielding material and the gamma ray shielding properties were also tested with energy of 59.5 keV, 81.0 keV and 121.8 keV. For orthorhombic persimmon-like bismuth tungstate (Bi2WO6) which were produced under weak acidic or neutral condition (pH = 2, 5, 7), it was found that the linear attenuation coefficient of gamma ray grew by about 8 % when pH changing from 2 to 7 for all energy tested. While for tetragonal bismuth tungstate (Bi0.875W0.125O1.6875), weakly alkaline condition (pH = 9) induced significant decrease (9 %@59.5 keV, 17 %@81.0 keV and 11 %121.8 keV) of linear attenuation coefficient compared with neutral condition, which could be explained by the dramatic crystal structure change of bismuth tungstate. More alkaline synthesizing condition would make finer granularity of bismuth tungstate and the linear attenuation coefficient increased when pH change from 9 to 12. In addition, obvious differences of mechanical properties were also observed between the composites prepared using different crystalline bismuth tungstates. The results of this study provide a reference for the development of new flexible radiation shielding materials with non-toxicity, light weight and high efficiency.

Discovery of Very High Energy Gamma-Ray Emissions from the Low-luminosity AGN NGC 4278 by LHAASO

Abstract The first source catalog of the Large High Altitude Air Shower Observatory (LHAASO) reported the detection of a very high energy gamma-ray source, 1LHAASO J1219+2915. This Letter presents a further detailed study of the spectral and temporal behavior of this pointlike source. The best-fit position of the TeV source (R.A. = 185.°05 ± 0.°04, decl. = 29.°25 ± 0.°03) is compatible with NGC 4278 within ∼0.°03. Variation analysis shows an indication of variability on a timescale of a few months in the TeV band, which is consistent with low-frequency observations. Based on these observations, we report the detection of TeV γ-ray emissions from this low-luminosity active galactic nucleus. The observation by LHAASO's Water Cherenkov Detector Array during the active period has a significance level of 8.8σ with a best-fit photon spectral index Γ = 2.56 ± 0.14 and a flux f 1–10 TeV = (7.0 ± 1.1sta ± 0.35syst) × 10−13 photons cm−2 s−1, or approximately 5% of the Crab Nebula. The discovery of VHE gamma-ray emission from NGC 4278 indicates that compact, weak radio jets can efficiently accelerate particles and emit TeV photons.

Effect of Bi2O3 Particle Size on the Radiation-Shielding Performance of Free-Lead Epoxide Materials against Ionizing Radiation.

In this work, we studied the effect of bismuth oxide particle size and its attenuation capacity as a filler additive in epoxy resins. Six samples were prepared according to the amount of microparticles and nanoparticles in the sample and were coded as ERB-1, ERB-2, ERB-3, ERB-4, ERB-5, and ERB-6. One of the composite epoxies contained Bi2O3 microparticles at a 50:50 ratio (ERB-6) and was chosen as the control composite, and the number of microparticles (MPs) was gradually decreased and replaced by nanoparticles (NPs) to produce epoxy-containing Bi2O3 nanoparticles at a 50:50 ratio (ERB-1). The morphological and thermal characteristics of the studied composites were tested. The attenuation capability of the prepared composites, which is determined by the Bi2O3 particle size, was determined experimentally using a semiconductor detector, an HPGe-detector, and three different gamma-ray point sources (Am-241, Co-60, and Cs-137). The linear attenuation coefficient (LAC) of ERB-3, which contained 30% nanoparticles and 20% microparticles, had the highest value compared to the other composites at all the energies discussed, while the ERB-6 composite had the lowest value at all energies. The radiation-shielding efficiency (RSE) of the prepared samples was determined at all discussed energies; at 662 keV, the radiation-shielding efficiency values were 15.97%, 13.94%, and 12.55% for ERB-3, ERB-1, and ERB-6, respectively. The statistics also proved that the attenuation capacities of the samples containing a combination of nanoparticles and microparticles were much superior to those of the samples containing only microparticles or nanoparticles. A ranking of the samples based on their attenuation capacity is as follows: ERB-3 > ERB-4 > ERB-2 > ERB-1 > ERB-5 > ERB-6.

Real-time gamma-ray energy spectrum / dose monitor with k-α method based on sequential bayesian estimation

Medical applications of radiation have been widely spread until now. However, the exposure of medical staff is sometimes overlooked, because treatment of patients is the first priority. The purpose of this study is to develop a small and light monitor that can measure the energy spectrum and dose of gamma-rays at the same time in real-time for medical applications. Using the monitor, the medical staff could be guided to be more aware ofthe risk of radiation, and finally the exposure to them could be substantially suppressed. So far, a CsI scintillator has been chosen as a detection device of gamma-rays and combined with a Multi-Pixel Photon Counter (MPPC) to develop a prototype monitor. Then we confirmed its basic performance with standard gamma-ray sources. To achieve the real-time measurement, α method (sequential Bayesian estimation) was adopted and improved to propose a new unfolding process, named k-α method, with which the convergence speed could really be accelerated to realize real-time measurement. Also, gamma-ray measurements with a mixed source of 133Ba, 137Cs and 60Co were carried out to confirm the validity of the present monitor. As a result, it was found that gamma-ray energy spectrum could be estimated successfully in several-tens seconds in the field of around 6 μSv/h. For the dose estimation, the correct values could be estimated just after starting measurement.

Geminga's pulsar halo: An X-ray view

Geminga is the first pulsar around which a remarkable gamma-ray halo extending over a few degrees was discovered at TeV energies by MILAGRO and HAWC and later by H.E.S.S., and by -LAT in the GeV band. More middle-aged pulsars have exhibited gamma-ray halos, and they are now recognised as an emerging class of Galactic gamma-ray sources. The emission appears in the late evolution stage of pulsars, and is most plausibly explained by inverse Compton scattering of CMB and interstellar photons by relativistic electrons and positrons escaping from the pulsar wind nebulae. These observations pose a number of theoretical challenges, particularly the origin of the inferred, significantly lower effective diffusion coefficients around the pulsar when compared to typical Galactic values. Tackling these questions requires constraining the ambient magnetic field properties, which can be achieved through X-ray observations. If the gamma-ray halos originate from a distribution of highly energetic electrons, synchrotron losses in the ambient magnetic fields of the same particles are expected to produce a diffuse X-ray emission with a similar spatial extension. We present the most comprehensive X-ray study of the Geminga pulsar halo to date, utilising archival data from and . Our X-ray analysis covers a broad bandwidth ($0.5 79$ keV) and large field of view ($ for the first time. This was achieved by accurately measuring the background over the entire field of view, and taking into account both focused and stray-light X-ray photons from the pulsar halo with . We find no significant emission and set robust constraints on the X-ray halo flux. These are translated to stringent constraints on the ambient magnetic field strength and the diffusion coefficient by using a physical model considering particle injection, diffusion, and cooling over the pulsar’s lifetime, which is tuned by fitting multi-wavelength data. Our novel methodology for modelling and searching for synchrotron X-ray halos can be applied to other pulsar halo candidates.

Gamma-ray shielding features of Co1-xCuxFe2O4 ferrite: A combined experimental, theoretical and simulation investigation

This study describes a rapid synthesis of Co1-xCuxFe2O4 nanoparticles using sol–gel auto-ignition and the produced materials were examined using different techniques such as XRD (X-Ray Diffraction), UV–Vis (Ultraviolet–visible), (FTIR Fourier Transform Infrared Spectroscopy), FE-SEM (Field emission scanning electron microscopy), and EDS (Energy-dispersive X-ray spectroscopy) to explore their structural, optical, and functional group morphological properties, and elemental analysis. Additionally, utilizing several gamma-ray sources and a NaI (Tl) scintillation detector, we studied the gamma-ray shielding characteristics for the prepared materials. Experimental results were validated by the results of XCOM program and the Geant4 simulations. For four chosen ferrites, the gamma ray energy absorption build-up factor is investigated at 0.01–15 MeV incident photon energy and penetration depths of 1–40 mean free path, mfp, using the geometric progression fitting technique. Ferrite samples can be employed as radiation attenuators across a range of nuclear domains, as per the findings of this study. In comparison to the other spinel ferrites, the Co1-xCuxFe2O4 (x = 0.75) ferrite demonstrated superior shielding capabilities. Important details regarding the physio-chemical properties of spinel ferrites and their ability to shield against gamma radiation are provided in the present study.

Study of a method for theoretical calculation of the efficiency of a LaBr3(Ce) for detecting gamma-rays from point sources

A theoretical model for calculating the full-energy peak efficiency of scintillator detector is proposed in this paper. The effective penetration distance of gamma-rays in Ø3.81cm × 3.81 cm LaBr3(Ce) crystal, aluminum shell and MgO reflector is analyzed. The calculation model for point source detection efficiency is derived, and the attenuation of gamma-rays in the detector shell is computed by theoretical calculation method. This method is used to calculate the efficiency of LaBr3(Ce) with a size of Ø3.81 × 3.81 cm for detecting gamma-rays from point sources of 137Cs and 60Co located in different positions. Compared with experimental data and Monte Carlo (MC) simulation results, the maximum relative deviation is less than 5%. The attenuation of gamma-rays with an energy of 60 keV is more than 50%. The fitted efficiency calibration curve in the energy range of 60 keV–1500 keV is in good agreement with the simulation results. The results show that this method is suitable for calculating the efficiency of the LaBr3(Ce) detector using point sources, especially for analyzing low-energy gamma ray sources. By taking into account the attenuation of the gamma-rays by the detector shell, the measurement accuracy can be effectively improved. The proposed method can be extended for the efficiency calibration of scintillator detectors with various shapes and provides a new approach for 'source-less' efficiency calibration of detectors.

Balancing Performance and Portability: A Study on CsI(Tl) Crystal Sizes for Real-Time Gamma-Ray Spectrum and Dose Monitoring

Current radiation dosimeters sometimes face accuracy limitations or provide only cumulative doses over long periods. To contribute to this area, we developed a portable monitor that measures the energy spectrum and dose of gamma rays in real time. To achieve this, we used an improved sequential Bayesian estimation algorithm. The dose rate was then derived from the energy spectrum by applying a flux-to-dose conversion coefficient. The monitor consists mainly of a CsI(Tl) scintillator and a multi-pixel photon counter (MPPC). In developing this device, we focused on striking a balance between measurement accuracy, ease of use, and portability. As an essential aspect of the research, we investigated the influence of the CsI(Tl) crystal size on the performance of the monitor to determine an optimal size. This was accomplished by calculating the detection efficiency and energy resolution through experimental measurements using standard gamma-ray sources and simulations using MCNP5. Within the scope of the research, detector response functions were created for each crystal size for an energy range of 10 keV to 3 MeV. Considering an optimal balance of detection efficiency and energy resolution alongside a compact size suitable for portable applications, the crystal measuring 2.6 × 2.6 × 1.3 cm3 was deemed preferable.

Numerical intercomparison of PHITS and Geant4 Monte Carlo codes for fast neutron inelastic scattering applications

Fast neutron inelastic scattering is a promising non-destructive assay technique for various analytical applications. As an active neutron interrogation technique, its performance is a function of various different factors and parameters that require optimization. Monte Carlo simulation codes are indispensable for such tasks. However, the internal simulation routines implemented in such codes can rely on different physical models that can yield discrepancies in the simulation results. In this work we conduct an intercomparison of PHITS and Geant4 codes performance in application to fast neutron inelastic scattering simulations. The goal of this paper is twofold. First, we explain the differences in code configuration with respect to gamma and neutron transport, as well as internal simulation routines. Second, we conduct a performance assessment of the two codes using two different measurement configurations. One configuration consisted of a source of gamma rays in a broad energy range (100–9000 keV) and a CeBr3 detector. The other configuration consisted of a monoenergetic 2.5 MeV fast neutron source, Fe, Nd, Dy, B targets and a CeBr3 detector. Selected simulation configurations were chosen with a goal to compare the performance differences in neutron energy distribution, produced prompt gamma rays and energy deposition in CeBr3 detector between the two codes. Results of our study reveal a good coherence of both codes performance in the application of fast neutron inelastic scattering simulations. The simulation geometries and observed differences are described in detail.

Radiation shielding parameterizations of FeSO4, CuSO4, NiSO4 and ZnSO4 Compounds: using (XRF) technique & Monte Carlo FLUKA approach

The mass attenuation coefficient (MAC) for different sulphate compounds can be estimated by using the Energy Dispersive X-ray Fluorescence (EDXRF), also known as X-ray Fluorescence (XRF) technique. The X-ray photons emitted have different energies depending on incident photon energy, atomic weight, and molecular structure of tested material. The excitation energy of the gamma rays source with 59.53 keV was obtained by using 241Am (40 µci). The (MAC) for sulphate compounds of a different element (Fe, Ni, Cu, Zn) have been calculated by measuring the intensity difference for kα in pure elements and their compounds. The determined results showed that the maximum value for (µm) was in FeSO4. These results are consistent with the theoretical value obtained by the XCOM software in addition to investigating the wide energy response of photon interaction with the introduced compounds using the FLUKA Monte Carlo simulation software. The mass attenuation coefficient (MAC) of these compounds is numerically evaluated in the energy range 0.015-15 MeV using the FLAIR code. The computed (µm) is used to generate significant radiation protection factors such as the linear attenuation coefficient (LAC), half-layer value (HVL), effective (Zeff), and equivalent (Zeq) atomic number. For studying the shielding effectiveness and efficiency, for fast and thermal neutron radiation, the removal cross-section ƩR was given.

An experimental feasibility study of a 4π gamma-ray imager using detector response patterns

We constructed a gamma-ray imager that estimates the distribution of gamma-ray sources based on the response patterns of multiple gamma-ray detectors randomly positioned in three-dimensional space. The Coded Cube Camera for Gamma-ray (C3G), comprising eight Gd3Al2Ga3O12 (Ce) scintillator and eighteen lead cubes is housed in a cubical casing with an 86 mm edge length and weighs approximately 600 g. The results of the 4π imaging experiment confirmed the feasibility of imaging a 10 MBq 137Cs source 3 m away for a 10 min measurement. C3G operates with only eight channels, instead of the hundreds needed by a typical imager. This setup allows for a simplified circuit and reconstruction algorithm, resulting in a cost-effective and reliable system. With its compact and lightweight design and 4π field of view, this technology is expected to find extensive applications in astronomy, medicine, nuclear security, and decommissioning projects.

Non-thermal emission from microquasar jets: The case of GRS 1915+105

Microquasars (μQs) represent a prominent population of Galactic sources, from which broadband non-thermal emission was detected. At present, the potential of μQs as sources of gamma-ray emission is poorly understood and constrained. In most cases, even the power of μQ jets remains largely uncertain, and this hinders the study of gamma-ray generation in these sources. Using observational data obtained in the radio band, we derive an estimate of the jet power in one of the most famous Galactic μQ, in GRS 1915+105. Compared to other studies of this subject, we additionally consider constraints related to the energy dissipated at internal shocks in the jet, the conditions at which are obtained using properties of the radio blobs detected in the jets. We show that even if one subtracts the rest-energy of matter in the jet, the jet power in this source should be very high, 1039ergs−1, or even higher. The properties of the detected radio emission favor jets with a Gauss-strength magnetic field at parsec distances from the black hole. Such a strong magnetic field should suppress inverse Compton (IC) emission from relativistic electrons, at least from parsec-scale jet. On the other hand, this strong magnetic field makes μQ jets perfect proton accelerators. If present, protons should easily be accelerated in the ultra-high-energy regime. However, due to a diluted target, protons should not lose a notable fraction of their energy in the jet, injected into the interstellar medium at the jet termination. This should significantly enhance the density of cosmic rays in the vicinity of GRS 1915+105. This may manifest itself as an extended gamma-ray source or as several compact sources if the target gas has a highly inhomogeneous distribution. This analysis has direct implication for studying Galactic μQ with such gamma-ray observatories as LHAASO, CTA, and SWGA in the next decades.

Fabrication and Evaluation of Spectroscopic Grade Quasi-hemispherical CdZnTe Detector

Background: This study focuses on the fabrication and characterization of quasi-hemispherical Cd<sub>0.9</sub>Zn<sub>0.1</sub>Te (CZT) detector for gamma-ray spectroscopy applications, aiming to contribute to advancements in radiation measurement and research.Materials and Methods: A CZT ingot was grown using the vertical Bridgman technique, followed by proper fabrication processes including wafering, polishing, chemical etching, electrode deposition, and passivation. Response properties were evaluated under various external bias voltages using gamma-ray sources such as Co-57, Ba-133, and Cs-137.Results and Discussion: The fabricated quasi-hemispherical CZT detector demonstrated sufficient response properties across a wide range of gamma-ray energies, with sufficient energy resolution and peak distinguishability. Higher external bias voltages led to improved performance in terms of energy resolution and peak shape. However, further improvements in defect properties are necessary to enhance detector performance under low bias conditions.Conclusion: This study underscores the efficacy of quasi-hemispherical CZT detector for gamma- ray spectroscopy, providing valuable insights for enhancing their capabilities in radiation research field.

The impact of wurtzite and mesoporous Zn-Al-CO3 LDH on the performance of alkali-activated-slag: Setting times, compressive strength, and radiation attenuation

Although including wurtzite (ZnO) in cementitious materials significantly enhances gamma-radiation mitigation, its use is not recommended as it excessively prolongs the setting time and negatively affects the early strength. Hence, this study attempts to address these issues while enhancing radiation-shielding by including Zn-Al-CO3 layered double hydroxide (LDH) as an alternative for ZnO. Wurtzite and LDH nanoparticles were laboratory-prepared via the co-precipitation method; their specific surface areas were found to be 2290 and 65483 cm2/g, respectively, referring to the high reactivity of LDH. Five pastes were prepared; alkali-activated slag was used as a control specimen (0 wt% nanoparticles), while the others contained 0.5 and 1 wt% ZnO or LDH. The comparative study showed that incorporating Zn-phase as LDH solved the abovementioned problems. The setting time of LDH-modified specimens fits in the standard limit (50–375 mins), while others contain ZnO exceed this limit. The inclusion of 0.5 wt%LDH showed a remarkable enhancement in mechanical performance; compressive-strength values increased by 36.2 and 31.1 % concerning the control specimen after 1 and 28-days, respectively. In contrast, the same dose of ZnO reduced strength by 26.3 and 13 %. Moreover, the LDH-modified specimens displayed the highest linear-attenuation coefficient and lowest half-value layer when exposed to two gamma-ray sources (Co-60 and Cs-137). The X-ray diffraction, thermogravimetric analysis and scanning electron microscope proved that the formation of Zn(OH)2 in the ZnO-modified specimens is the main reason behind high retardation and reduction in compressive-strength. The filling/active-seeds/chemical-reactivity actions of LDH resulted from its high surface area, forming a high amount from different strength-giving-phases (compact structure) in the LDH-modified specimens.

Enhancing mechanical and radiation shielding properties of concrete with lead monoxide and granodiorite: Individual and synergistic effects at micro and nano particle scales

AbstractThis study investigates the individual and combined effects of micro and nano lead monoxide (PbO) and granodiorite (GD) on concrete's mechanical and radiation shielding properties. Both materials were partially substituted for cement at varying ratios. Additionally, mixtures with optimal radiation shielding performance were prepared to explore the synergy of combining them. The mentioned materials are used for the first time in an extensive study at the nano scale to investigate their impact on concrete's mechanical properties, microstructure, and gamma radiation attenuation. Two gamma ray sources of uranium (U238) and cesium (Cs137) were used measure the radiation attenuation coefficients for all designed concrete mixes. A simple methodology was followed to assess the concrete shields efficiency via utilizing portable handheld gamma‐ray spectrometer that offers two reading modes. Results indicated that increasing the ratio of PbO is directly proportional to the concrete ability to attenuate radiation, where the optimal individual replacement ratios were recorded at 5% for micro and nano particle sizes. At this ratio, the linear attenuation coefficient (μ) values were improved by 39.57% and 24.78% for the nano and micro PbO, respectively. Additionally, the optimal ratio for improving mechanical properties was at 3% and 2% for nano and micro PbO, while the higher ratios showed a decline in mechanical properties especially at 5% micro PbO with 7.02% reduction in the compressive strength value. Regarding GD powder, the optimal replacement ratios for improving concrete radiation shielding were consistent with those enhancing its mechanical properties at 4% and 7% in both nano and micro scales, respectively. The combined mixes further enhanced the overall concrete performance, especially its radiation shielding ability. Compared to the control mix, the compressive strength, tensile strength, and μ were increased by 25.7%, 16.2%, and 44.7% at the optimal mixture of 5% nano PbO + 4% nano GD.

Experimental evaluation of radiation shielding characteristics of borate-based-glass system reinforced with titanium oxide

In this work, the attenuation capability of new Borate-based-glass system reinforced with titanium oxide containing PbO, CaO, TiO2 and B2O3 with different percentages was determined. Four different glass samples were synthesized by experimental technique using high pure germanium detector at different gamma ray sources using narrow beam method. The experimental method was verified by XCOM software. The values of the two methods were close and the relative deviation was satisfactory (less than 5 %) for all gamma energies (0.060, 0.662, 1.173 and 1.333 MeV). The highest linear attenuation coefficient (LAC) values achieved at low radiation energy of 0.0595 MeV. The Highest LAC values were 13.64, 13.97, 14.32 and 14.67 cm−1 for samples PCBT-1, PCBT-2, PCBT-3 and PCBT-4 in the same order, respectively. Conversely, the lowest LAC values in the examined energy range were found at 1.333 MeV. The lowest LAC values were 0.259, 0.266, 0.272 and 0.279 cm−1 for the aforementioned glasses, respectively. At 0.662 MeV, the transmission factor (TF) values decreases as 64.18, 63.54, 62.88 and 62.19 % as TiO2 content increases as 5, 10, 15 and 20 mol % in the same order, respectively. The decreases in TF values was linked to an observable increase in the radiation protection efficiency (RPE). The increase in RPE with the increase of TiO2 content confirms that the addition of TiO2 leads to an improvement in the radiation shielding performance for the prepared glasses.

Galaxy group-associated distances to very high energy gamma-ray emitting BL Lacs KUV 00311−1938 and S2 0109+22

ABSTRACT Blazars constitute the most numerous source class in the known extragalactic population of very high energy (VHE) gamma-ray sources. However, determining their redshifts is often challenging due to weak or non-existent emission lines in their spectra. This study focuses on two BL Lacs, KUV 00311−1938 and S2 0109+22, where previous attempts at redshift determination have faced difficulties. By combining spectroscopic observations with photometric redshift estimates, we tentatively assign a redshift of $z=0.634$ to KUV 00311−1938 and a likely redshift of $z=0.49$ to S2 0109+22. Establishing redshift estimates for high-redshift blazars is crucial for understanding extragalactic VHE gamma-ray sources and their interactions with the surrounding Universe.