Search

The present study aims to investigate the gamma photon-neutron attenuation parameters of the marble concrete such as the linear attenuation coefficient (mu), Mass Attenuation Coefficient (MAC), Half Value Layer (HVL), neutron removal cross-section (Sigma(R)), and Exposure Buildup Factor (EBF) by MCNPX Monte Carlo code to examine the possibility of utilizing selected samples against gamma photon-neutron. The six types of marble concrete were exposed to different energies ranging from 511 to 1332 keV. The shielding effectiveness of the selected marble concrete was compared to each other and the obtained results show that the increment of the penetration depth causes an increase in the value of EBF and the sharp peak is monitored at 200 keV. The Sigma(R) (neutron removal cross-section) values were also reported for all types of marble concrete. The outcomes depict that n-ary sumation (R) is strongly relevant to the weight fractions of light elements of the selected shielding materials. Furthermore, the variations of sigma(a) (total atomic cross-section) were reviewed and discussed versus wide energy ranges. Findings in all sections confirmed that NM-15 has the best gamma photon shielding quality in comparison with the other types of marble concrete, while NM-0 and NM-15 show the highest neutron proficiency.

The gamma photon and neutron shielding effectiveness of borosilicate glasses with alumina in the chemical structure 40SiO2.10B2O3.xBaO.(45 − x)CaO.5Al2O3.yZnO.zMgO glasses (20 ≤ x ≤ 40 mol% and y = z = 6 wt%) was evaluated. The investigated glasses were coded as BCBSA-20B (barium oxide (BaO) = 20 mol%) to BCBSA-40B (barium oxide = 40 mol%). The results showed that the mass attenuation coefficient (MAC) increased when barium oxide increased in the samples, and the samples were arranged in order as BCBSA-20B eff). Moreover, the neutron shielding competences of glasses have been determined by way of calculating the removal cross-section for the fast neutrons, Σ R (cm−1), which was the highest for the BCBSA-40B glass (Σ R = 0.0994 cm−1) among the studied samples. In addition, mass stopping power (Ψ) and the projected range (Φ) for proton and alpha particles were also calculated. It was found that the BCBSA-40B sample has the lowest Ψ and Φ among the studied glasses. It can be concluded that the replacement of the calcium oxide (CaO) content with the barium oxide contents enhances the shielding capacity against the charged particles, electromagnetic radiation and the fast neutrons. The finding of recent investigations can be useful for advanced nuclear engineering and protection studies.

Phy-X/PSD software was applied to understand the gamma photon shielding characteristics of SeO2–Ag2O–TeO2 glass systems. The highest attenuation coefficients occurred at 15 keV (between 39.576 and 48.978 cm2/g) and the lowest at 15 MeV (between 0.0369 and 0.0392 cm2/g). The results showed that the attenuation factors highly depended on the concentration of TeO2, and μ/ρ increased as TeO2 changed from 28 to 70 mol%. The maximum effective atomic number values were between 15 keV and 0.08 MeV and the values at 0.04 MeV were 45.81, 46.55, 47.23, 47.84, 48.91, and 49.38 for SeAgTe1, SeAgTe2, SeAgTe3, SeAgTe4, SeAgTe5, and SeAgTe6, respectively. From the half value thickness results, the SeAgTe6 had the lowest HVT, and thus the best attenuation. The worst attenuation was found for the SeAgTe1, which had the least amount of TeO2 and the lowest density (ρ = 5.66 g cm-3). The results also revealed that there was a rapid increase in the tenth value layer (TVL) for all of the glasses up to 1 MeV as the energy increased, and then the TVL increased at a slower rate. The TVL also confirmed that the attenuation competence of the glasses increased when the TeO2 content increased from 28 mol% to 70 mol%. The attenuation of the SeAgTe1–SeAgTe6 glasses was much better than that of ilmenite, steel-magnetite concrete, and RS-360 glass, since these glasses had lower mean free paths, whereas the attenuation properties of the RS-520 glass were comparable to the SeAgTe3.

The significance and novelty of the present work are the preparation of the non-lead ceramic by the general formula of (1-x) K0.5Na0.5NbO3-xLa Mn0.5Ni0.5O3 (KNN-LMN) with different x (0 . . . > (HVL)(x=0.25) is reported for half-value layer values against gamma photon. From the attained results, it can be concluded that increaisng the rate of x results in the better shielding proficiency in terms of neutron and gamma photon for chosen KNN-LMN-based lead-free ceramics.

WOS: 000462778100022 In the present work, we determined the gamma-ray attenuation characteristics of eight different polymers(Polyamide (Nylon 6) (PA-6), polyacrylonitrile (PAN), polyvinylidenechloride (PVDC), polyaniline (PANI), polyethyleneterephthalate (PET), polyphenylenesulfide (PPS), polypyrrole (PPy) and polytetrafluoroethylene (PTFE)) using transmission geometry utilizing the high resolution HPGe detector and different radioactive sources in the energy range 81-1333 keV. The experimental linear attenuation coefficient values are compared with theoretical data (WinXCOM data). The linear attenuation coefficient of all polymers reduced quickly with the increase in energy, at the beginning, while decrease more slowly in the region from 267 keV to 835 keV. The effective atomic number of PVDC and PTFE are comparatively higher than the Z(eff) of the remaining polymers, while PA-6 possesses the lowest effective atomic number. The half value layer results showed that PTFE (C2F4, highest density) is more effective to attenuate the gamma photons. Also, the theoretical results of macroscopic effective removal cross section for fast neutrons (Sigma(R)) were computed to investigate the neutron attenuation characteristics. It is found that the Sigma(R) values of the eight investigated polymers are close and ranged from 0.07058 cm(-1) for PVDC to 0.11510 cm(-1) for PA-6. (C) 2018 Korean Nuclear Society, Published by Elsevier Korea LLC. Scientific Research Projects Coordination Unit of Giresun University [FEN-BAP-A-160317-23] The present work was done with the support of the Scientific Research Projects Coordination Unit of Giresun University under Project no: FEN-BAP-A-160317-23.

In this paper, we studied the gamma photon attenuation properties for different germanate glasses systems with composition Sb2O3–GeO2–SiO2–Al2O3, TeO2–WO3–GeO2, GeO2–TeO2/SiO2–PbO–CaO–Tm2O3 and B2O3–GeO2–Gd2O3–Eu2O3–GdF3–BaF2. The mass attenuation coefficients (μ/ρ) for the selected germanate glasses were calculated at different energies (between 0.015 MeV and 15 MeV) using the MCNPX code. The calculated MCNPX μ/ρ values then compared with the WinXCom data to check the accuracy in the results. The results showed that the Sb2O3 replacement by SiO2 causes a decrease in μ/ρ for Sb2O3–GeO2–SiO2–Al2O3 glass system. Also, it is found that for TeO2–WO3–GeO2 glass system, μ/ρ decreases as GeO2 content increases from 1 to 20 mol%. While for GeO2–TeO2/SiO2–PbO–CaO–Tm2O3 glass system, the results revealed that the glass samples contain TeO2 possess higher μ/ρ values than the samples contain SiO2. For the B2O3–GeO2–Gd2O3–Eu2O3–GdF3–BaF2 glasses, we found that the μ/ρ values decrease as BaF2 is increased from 0 to 15 mol%. Moreover, it is found that 50Sb-0Ge for series 1, TWG0 for series 2, 2G4T for series 3 and X = 0 for series 4 glass samples among the studied glasses have the highest effective atomic number values. On the basis of the results achieved, 50Sb-0Ge, TWG0, 2G4T and X = 0 samples have the best radiation shielding characteristics among the selected glasses.

Electron-positron pair creation by the mean of two real photon collision (linear Breit-Wheeler process) is one of the most basic quantum electrodynamics process, and is believed to underlie a large amount of high energy astrophysical phenomena, such as the Universe opacity to TeV photons or the production of pair plasmas near compact objects (AGN, pulsars). However, this process has never been directly observed in the laboratory since its prediction in 1934, mainly because of the absence of high flux MeV-range photon sources. Due to the continuous development of high-power and high-intensity laser systems, the production of such photon sources become however conceivable. Despite the diversity of methods to produce energetic photons by lasers, previous estimates seems to show that the radiation sources produced whether by the slowing-down of electrons in matter (Bremsstrahlung), by the linear inverse Compton scattering process, or by the multi-photon inverse Compton scattering process (sometimes called synchrotron-like) are among the most credible sources for the electron-positron pair production by two real photon collisions. The interaction of such multi-MeV photons with matter could however creates other electron-positron pairs, which could constitute a background noise for the detection of this process. The goal of this thesis is to optimize the production of MeV-range gamma photons by the mean of the interaction of a laser with various kind of targets (simple or structured solid targets) in order to prepare photon-photon collision experiments on existing or currently building laser systems. A semi-analytical model allow firstly to optimize linear Breit-Wheeler pair production in term of the photons sources parameters. Particularly it is shown that, concerning Bremsstrahlung photon sources, the current laser systems already permit to reach the optimum photon energy distributions, opening the possibility to design such experiments at high repetition rate. This study is completed with numerical simulations modeling the electron acceleration in the laser-target interaction (via a Particle-In-Cell code), the gamma photon generation by the electron propagation in matter (via a Monte Carlo code) and the electron-positron pair production in photon-photon collisions (via the TrILEns code). These findings could then be used as a basis to design such experiments on existing or currently building laser systems.; La création de paires électron-positron par collision de deux photons réels (processus Breit-Wheeler linéaire) est un des processus de base de l’électrodynamique quantique, et est supposé sous-tendre un large éventail de phénomènes astrophysiques des hautes énergies, tels que l’opacité de l’Univers aux photons TeV ou la production de plasmas de paires au voisinage d’objets compacts (AGN, pulsars). Cependant, ce processus n’a jusqu’à présent jamais été directement observé en laboratoire depuis sa prédiction en 1934, et ce principalement à cause de l’absence de sources de photons d’énergie autour du MeV de suffisamment haut flux. Grâce au développement continu des systèmes laser de haute puissance et de haute intensité, la production de telles sources de photons devient toutefois désormais envisageable. Malgré la diversité des approches possibles pour la génération de photons énergétiques par laser, de précédentes estimations semblent indiquer que les sources produites : par rayonnement de freinage d’électrons dans la matière (Bremsstrahlung), ou via les processus Compton inverse linéaire ou Compton inverse multiphoton (parfois appelé synchrotron-like), soient des candidates parmi les plus crédibles pour la production de paires électron-positron par collision de deux photons réels. L’interaction de ces photons multi-MeV avec de la matière peut toutefois aussi créer d’autres paires électronpositrons, qui pourraient constituer une source de bruit pour la détection de ce processus. L’objectif de cette thèse est d’optimiser la production de photons d’énergies autour du MeV générés lors de l’interaction d’un laser avec différent types de cibles (cibles solides simples ou structurées) afin de préparer des expériences de collision de photons sur des installations laser existantes ou en cours de construction. Un modèle semi-analytique permet tout d’abord d’optimiser la production de paires électron-positron par le processus Breit- Wheeler linéaire en fonction des paramètres des sources de photons. En particulier il est montré que, pour des sources de photons produits par Bremsstrahlung, les installations laser existantes permettent d’ores et déjà d’atteindre les distributions en énergies optimales, permettant ainsi d’envisager de telles expériences à haut taux de répétition. Cette étude est complétée par des simulations numériques permettant de modéliser l’accélération d’électrons lors de l’interaction du laser avec des cibles structurées (via un code Particle-In-Cell), la génération des photons gamma lors de la propagation d’électrons dans la matière (via un code Monte Carlo) ainsi que la création de paires électron-positron lors de la collision de ces photons gamma (via le code TrILEns). Ces développements pourraient alors servir de base à la préparation de futures expériences sur des installations laser actuelles.

In this article, the full energy peak efficiency of NaI detector using non-axial cylindrical sources is calculated by using a new efficient theoretical approach. This approach depends on using the efficiency transfer method and analytical calculations of the average path length of a gamma photon inside the source to the detector system. Measured efficiencies made by using 152Eu aqueous radioactive cylindrical sources with volumes 25 ml and 400 ml. Comparing calculated efficiencies to the measured one showed good agreement enabling the validation of this approach.

Данная работа посвящена изучению источников мощного энергетического потока гамма-излучения, которые могли бы быть реализованы в лабораторных условиях. В частности, преследуется цель выявить наиболее перспективный способ создания гамма-излучения, а также провести его анализ на предмет эффективности. Для этого в работе произвелось сравнение ряда источников гамма-излучения. После, для самого перспективного способа генерации, была разработана программа, которая продемонстрировала эффективность выбранного источника. Программа основана на использовании двух численных методов, а именно – метода Монте-Карло и итерационного метода Ньютона. Результатом программы является зависимость, отражающая потенциал выбранного источника. Полученный результат был сравнен с аналогичными результатами другой современной статьи. Были внесены некоторые корректировки и дополнительные пояснения. Так как исследование далёких объектов в спектре гамма-излучения приводит к необходимости учитывать искажение излучения, вызванное его взаимодействием с межгалактическим пространством, то после создание источника гамма излучения появится возможность моделировать поглощение гамма-излучения, на основе чего могут быть разработаны методы восстановления спектра объектов., The given work is devoted to investigation of sources of powerful gamma radiation energy flux that can be implemented in the laboratory conditions. Particularly, the goal is to define the most perspective way to create a gamma radiation and analyses its efficiency. For this purpose in this work we compared a number of gamma radiation sources. After we developed a program for the most perspective generation method, and this program has shown efficiency of the method. The program is based on two numerical methods, namely Monte Carlo method and Newton's iterative method. The program's result is the dependence reflecting the potential of the selected source. The result was compared with similar results from another contemporary article. Some adjustments and additional clarifications have been made. Since the study of the distant objects in the gamma radiation spectrum leads to the need to take into account the distortion of radiation caused by its interaction with the intergalactic space, after creating the gamma radiation source there will be a possibility to model the gamma radiation absorption, and based on this possibility methods can be developed to restore the spectrum of objects.

We present here a 16-channels ASIC for SiPMs readout in gamma-ray spectroscopy applications. Thanks to the automatic-gain-adjustment technique, the ASIC allows to achieve a high Dynamic Range (85dB). In gamma-ray measurements with SiPMs and LaBr3 scintillator, the ASIC allows to achieve PMT-like spectroscopy performances as well as capability to reconstuct the gamma photon point of interaction in scintillation crystals.

To observe the direct effect of molybdenum reinforcement on nuclear radiation shielding properties, a detailed investigation was performed with a group of bismuth borate glasses. Accordingly, glass samples with the nominal compositions (65-x)B2O3 + 20Bi(2)O(3) + 15Na(2)O + xMoO(3): x = 0, 1.5, 3, 4.5, 6 and 7.5 wt% have been synthesized by the solid state conventional method. The samples were named as M0 (x = 0), M1 (x = 1.5), M2 (x = 3), M3 (x = 4.5), M4 (x = 6) and M5 (x = 7.5). Physical characteristics and gamma-photon attenuation properties of (M0-M5) glasses have been investigated via MCNPX simulation code and XCOM program. XRD patterns confirmed that M0-M5 glasses were in amorphous nature. The density of the prepared glasses increased from 4.4104 for M0 glass sample to 5.3012 gm cm(-3), while molar volume decreased from 33.50083 to 28.92114 cm(3) mol(-1). The mass attenuation coefficient (mu(m)) increased with the increment of MoO3 concentration in mol% and followed the order: (M0)mu(m) < (M1)mu(m) < (M2)mu(m) < (M3)mu(m) < (M4)mu(m) < (M5)mu(m) at all photon energies. The mean free path (MFP), half value layer (HVL), and tenth value layer (TVL) for the prepared glasses M0-M5 have the same trend and follow the order: (M5)(MFP, HVL, TVL) < (M4) (MFP, HVL, TVL) < (M3) (MFP, HVL, TVL) < (M2) (MFP, HVL, TVL) < (M1) (MFP, HVL, TVL) < (M1) (MFP, HVL, TVL). The M5 glass sample (with maximum MoO3) achieved highest effective atomic number (Z(eff))and equivalent atomic numbers (Z(eq)) values for all photon energy ranges (low-medium-high). Among all the glass samples, the exposure build-up factor (EBF) and energy absorption build-up factor (EABF) values for M5 glass sample with the highest MoO3 additive are minimum due to the low amount of photons accumulated. These results indicate that M5 glass sample theoretically provides maximum protection for gamma-rays among all the samples.

In the present work, we studied the radiation shielding parameters such as mass attenuation coefficients, effective atomic number, half value layer, mean free path, macroscopic effective removal cross-sections and neutron transmission function for samarium doped lead alumino borate glasses containing barium, lithium and zinc oxides at medical diagnostic energies (between 20 and 150 keV) using MCNPX code. The results showed that the photon attenuation depends on the type of modifier used (i.e. ZnO, BaO or Li2O) and also, upon the energy of the photon. The higher mass attenuation coefficients were found for the glass containing BaO. The results also revealed that the glass containing Li2O has the maximum effective atomic number between 20 and 40 keV. In addition, some important neutron shielding parameters such as macroscopic effective removal cross-sections (ΣR) and neutron transmission function (N/N0) have been calculated for investigated glass samples. Keywords: XCOM, Glasses, MCNPX, Attenuation, Gamma photon, Neutron

We have identified a mechanism of collective nuclear de-excitation in a Bose-Einstein condensate of $^{135}$Cs atoms in their isomeric states, $^{135m}$Cs, suitable for the generation of coherent gamma photons. The process described here does not correspond to single-pass amplification, which cannot occur in atomic systems due to the large shift between absorption and emission lines, nor does it require the large densities associated to standard Dicke super-radiance. It thus overcome the limitations that have been hindering the generation of coherent gamma rays in many systems. Therefore, we propose an approach for generation of coherent gamma rays, which relies on a combination of well established techniques of nuclear and atomic physics, and can be realized with currently available technology., published in Physics Letters B

In this paper, the average energy of the $\gamma$ -photon ( $E_{\mathrm {a},\mathrm{ph}}$ ) is calculated and the correlation between $\log E_{\mathrm{a},\mathrm{ph}}$ and the logarithm of the synchrotron peak frequency ( $\log\nu_{\mathrm{p}}$ ) is discussed for a sample of 620 BL Lac objects. The results show that there exists a positive correlation between the $\gamma$ -photon energy and the synchrotron peak frequency for BL Lac objects, which implies that the $\gamma$ -ray emissions are related to the low-energy emissions of radio to X-ray bands, and the high energetic $\gamma$ -ray emissions are only partially from the synchrotron self-Compton process (SSC) for BL Lac objects.

Monte Carlo N-particle (MCNP) code has been used to simulate the transport of gamma photon rays of different energies (22, 31, 59.5 and 81 keV) to estimate the iron content in solutions. In this study, MCNP simulation results are compared with experiment and XCOM theoretical data. The simulation shows that the obtained results are in good agreement with experimental data, and better than the theoretical XCOM values. The study indicates that MCNP simulation is an excellent tool to estimate the iron concentration in the blood samples. The MCNP code can also be utilized to estimate other trace elements in the blood samples.

124I has a half-life of 4.2 days, which makes it suitable for imaging over several days along uptake and washout phases. However, it has a low positron branching ratio (23%), because high-energy gamma photons (602 to 1,691 keV), which degrade image quality, are emitted in cascade with positrons. In this study, we measured the single gamma photon fraction of 124I on Inveon PET scanner. Methods: to measure the single gamma photon fraction (SGF) of 124I, we measured the sensitivities of 124I and 18F from energy windows. The spill over ratios (SORs) of 124I were measured to assess the effect of single gamma photons fractions. Results: the SGF were 31%, 24%, and 3% in 0350 ~ 75, 0350 ~ 65, and 0350~ 55 keV, respectively. After single gamma corrections the SOR was decreased by 13% point. Conclusion: the proposed method for measuring the single gamma photons fraction of 124I will be useful to correct the single gamma photons from 124I PET. This information would also be useful to quantify the 124I PET.