Simulated X-ray Spectra Research Articles

Dosimetry and Monte Carlo modelling of the Papillon+ contact X-ray brachytherapy device

PurposeThis study aimed to develop and validate a Monte Carlo (MC) model for the Papillon+ contact x-ray brachytherapy (CXB) device, producing 50 kilovolt (kV) x-rays, specifically focusing on its application with a 25 mm diameter rectal applicator for contact therapy. Material and methodsThe validation process involved depth dose and transverse dose profile measurements using EBT3 gafchromic films positioned in a Plastic Water Low Energy Range phantom. The half-value layer (HVL) was further measured and derived from the simulated x-ray spectra. ResultsExcellent agreement within ± 2 % was achieved between the measured and simulated on-axis depth dose curves for the 25 mm rectal applicator. Transverse dose profile measurements showed a high level of agreement between the simulation and measurements, on average 3.1 % in contact with the applicator at the surface of the phantom and on average 1.7 % at 10 mm depth. A close agreement within 5.5 % was noticed concerning the HVL between the measurement and simulation. The simulated gamma spectra and 2D-dose distribution demonstrated a soft x-ray energy spectrum and a uniform dose distribution in contact with the applicator. ConclusionsAn MC model was successfully developed for the Papillon+ eBT device with a 25 mm diameter rectal applicator. The validated model, with its demonstrated accuracy in depth dose and transverse dose profile simulations, is a valuable tool for quality assurance and patient safety and, in a later phase, may be used for treatment planning, dose calculations and tissue inhomogeneity corrections.

Evidence for a nearly orthogonal rotator in GX 301–2 with phase-resolved cyclotron resonant scattering features

Abstract Cyclotron resonant scattering features (CRSFs) are the absorption features in the X-ray spectra of strongly magnetized accretion neutron stars (NSs), which are probably the most reliable probe to the surface magnetic fields of NSs. The high mass X-ray binary GX 301–2 exhibits a very wide, variable and complicated CRSF in the average spectra, which should be two absorption lines based on NuStar and Insight-HXMT observations. With the Insight-HXMT frequent observations, we performed the phase-resolved spectroscopy and confirmed two cyclotron absorption lines in the phase-resolved spectra, with their centroid energy ratio ∼1.6 − 1.7 in the super-critical luminosity case. A major hindrance in understanding those CRSFs is the very poorly constrained magnetic inclination angle, which is also a fundamental property of a NS and key to understanding the emission characteristics of a pulsar. Comparing the phase-resolved CRSF with simulated X-ray spectra, the magnetic inclination angle is found to be ≳ 70○, i.e., nearly orthogonal between the NS’s spin and magnetic axies. The implications of an orthogonal rotator and magnetic structure evolution in the accreting X-ray binary are also discussed.

Characterization of experimental and simulated micrometer-scale soft x-ray-emitting laser plasmas: Toward predictive radiance calculations

Experimentally generated and simulated soft x-ray plasma images and spectra from 1064 nm-driven laser-produced plasmas from slab tin are presented. Produced are small, micrometer-scale emission volumes with principle imaged emission lying between 1.2 and 2.5 nm. Experimental images of the soft x-ray emission of these plasmas are generated using a pinhole imaging system, which enables spatial characterization of the plasmas, and a simple transmission grating spectrometer with a 100 nm pitch grating is used to facilitate the spectral characterization of these plasmas. Plasmas are simulated under similar experimental conditions to those used with the single-fluid, single-temperature radiation-hydrodynamics code RALEF-2D. Coupling the simulation output with optical modeling methods demonstrates its promise as a capability for modeling the spatial and spectral behavior of soft x-ray-emitting tin plasmas at such scales and laser energies.

Understanding the X-ray emission spectrum after excitation with a source of X-rays: From theory to experiment

The modified Boltzmann-Chandrasekhar equation of transport for photons is the proper framework for describing the photon radiation field with a complete description of the polarization state. The characterization of the radiation field requires a detailed knowledge of the interactions of photons with mater and comprises also the contribution of the secondary electrons to the photon field through mechanisms like inner impact ionization and bremsstrahlung. It will be shown a solution obtained without the need of solving the coupled transport electrons-photons. With all these interactions, the theoretical characterization of the X-ray spectrum of emission after excitation with a source of X-rays can be straightforwardly obtained from the albedo solution to the equation. In this work it will be privileged a Monte Carlo (MC) solution. However, this solution is still far from an experimental measurement modified by the radiation detection devices, comprised the pulse electronics. In this work we put together a MC simulation able to get a detailed transport solution and a complete characterization of the contributions of the detection chain. It is discussed the influence of the single contributions and how they combine to make that a simulated X-ray spectrum matches well a real measurement.

The Statistical Uncertainties on X-Ray Flux and Spectral Parameters from Chandra ACIS-I Observations of Faint Sources: Application to the Cygnus OB2 Association

We investigate the uncertainties of fitted X-ray model parameters and fluxes for relatively faint Chandra ACIS-I source spectra. Monte Carlo (MC) simulations are employed to construct a large set of 150,000 fake X-ray spectra in the low photon count statistics regime (from 10 to 350 net counts) using the XSPEC spectral model-fitting package. The simulations employed both absorbed thermal (APEC) and nonthermal (power-law) models, in concert with the Chandra ACIS-I instrument response and interstellar absorption. Simulated X-ray spectra were fit assuming a wide set of different input parameters and C-statistic minimization criteria to avoid numerical artifacts in the accepted solutions. Results provide an error estimate for each parameter (absorption, N H, plasma temperature, kT, or power-law slope, Γ, and flux) and for different background contamination levels. The distributions of these errors are studied as a function of the 1σ quantiles, and we show how these correlate with different model parameters, net counts in the spectra, and relative background level. Maps of uncertainty in terms of the 1σ quantiles for parameters and flux are computed as a function of spectrum net counts. We find very good agreement between our estimated X-ray spectral parameter and flux uncertainties and those recovered from spectral fitting for a subset of the X-ray sources detected in the Chandra Cygnus OB2 Legacy Survey diagnosed to be association members and that have between 20 and 350 net counts. Our method can provide uncertainties for spectral parameters whenever formal X-ray spectral fits cannot be well constrained, or are unavailable, and predictions useful for computing Chandra ACIS-I exposure times for observation planning.

What Can We Learn about Compton-thin AGN Tori from Their X-Ray Spectra?<sup>1</sup>

We have developed a Monte Carlo code for simulation of X-ray spectra of active galactic nuclei (AGN) based on a model of a clumpy obscuring torus. Using this code, we investigate the diagnostic power of X-ray spectroscopy of obscured AGN with respect to the physical properties and orientation of the torus, namely: the average column density, \(\langle N_{\textrm{H}}\rangle\), the line-of-sight column density, \(N_{\textrm{H}}\), the abundance of iron, \(A_{\textrm{Fe}}\), the clumpiness (i.e. the average number of gas clouds along the line of sight), \(\langle N\rangle\), and the viewing angle, \(\alpha\). In this first paper of a series, we consider the Compton-thin case, where both \(\langle N_{\textrm{H}}\rangle\) and \(N_{\textrm{H}}\) do not exceed \(10^{24}\) cm\({}^{-2}\). To enable quantitative comparison of the simulated spectra, we introduce five measurable spectral characteristics: the low-energy hardness ratio (ratio of the continuum fluxes in the 7–11 keV and 2–7 keV energy bands), the high-energy hardness ratio (ratio of the continuum fluxes in the 10–100 keV and 2–10 keV energy bands), the depth of the iron K absorption edge, the equivalent width of the Fe K\(\alpha\) line, and the fraction of the Fe K\(\alpha\) flux contained in the Compton shoulder. We demonstrate that by means of X-ray spectroscopy it is possible to tightly constrain \(\langle N_{\textrm{H}}\rangle\), \(N_{\textrm{H}}\) and \(A_{\textrm{Fe}}\) in the Compton-thin regime, while there is degeneracy between clumpiness and viewing direction.

First-principles simulation of X-ray spectra of graphdiyne and graphdiyne oxides at the carbon K-edge.

The experimental C 1s near-edge X-ray absorption fine-structure (NEXAFS) spectra of graphdiyne (GDY) show an evident change at different exposure periods, which is explained by oxidation. Herein, to better understand the structure-spectra relationship and the influence of oxidization, we performed a first-principles simulation of the NEXAFS spectra and X-ray photoelectron spectra (XPS) of both pure GDY and its four typical graphdiyne oxides (GDO) at the carbon K-edge. Pure GDY contains one sp2-hybridized (C1) and two sp-hybridized (C2, C3) carbons, while oxidation introduces more nonequivalent carbons. The experimental NEXAFS spectrum exhibits the lowest peak at ca. 285.8 eV. It was found that the C 1s → π* excitation from the sp2-hybridized carbon atoms (C1) in pure GDY and the sp-hybridized atoms (C2, C3) in GDOs contributes to this peak. The two weak resonances at around 289.0 and 290.6 eV in the experiment are contributed by the carbon atoms bonded to the oxygen atoms. Meanwhile, we found that oxidization leads to an increase in the C 1s ionization potentials (IPs) by 0.3-2.7 eV, which is consistent with the XPS experiments. Our calculations provide a clear explanation of the structure-spectra relationships of GDY and GDOs, and the signatures are useful for estimating the degree of oxidation.

Automated total micro-IBA using Advanced Image Processing and Machine Learning

We have developed a Python code that aims at automatizing the analysis of generic micro-IBA data by associating statistical methods and machine learning algorithms. The code is organized in two parts: hyperspectral image analysis and composition prediction. In the first stage, main phases and local anomalies are detected separately using PCA and DWEST methods, respectively. In the prediction stage, we use the model generated by a trained artificial neural network. The network is fed with simulated particle and x-ray spectra generated from the SIMNRA and Gulys software codes. For particle spectra, we paid particular attention to the cross section selection that goes beyond already implemented SIMNRA functionalities. To limit the impact of the simulation time on the overall code performance, we make use of data augmentation. When using simulated data as input, we found that the trained neural network predicts stoichiometries and thicknesses with an excellent agreement, even for complex targets composed of several elements and layers. Regarding realistic experimental data, we still get reasonable predictions but remain dependant of cross section quality. The code can combine data from RBS, NRA, ERDA and PIXE and should pave the way for fully automatized micro-ion beam analysis.

On the choice of shape and size for truncated cluster-based x-ray spectral simulations of 2D materials.

Truncated cluster models represent an effective way for simulating x-ray spectra of 2D materials. Here, we systematically assessed the influence of two key parameters, the cluster shape (honeycomb, rectangle, or parallelogram) and size, in x-ray photoelectron (XPS) and absorption (XAS) spectra simulations of three 2D materials at five K-edges (graphene, C 1s; C3N, C/N 1s; h-BN, B/N 1s) to pursue the accuracy limit of binding energy (BE) and spectral profile predictions. Several recent XPS experiments reported BEs with differences spanning 0.3, 1.5, 0.7, 0.3, and 0.3eV, respectively. Our calculations favor the honeycomb model for stable accuracy and fast size convergence, and a honeycomb with ∼10nm side length (120 atoms) is enough to predict accurate 1s BEs for all 2D sheets. Compared to all these experiments, predicted BEs show absolute deviations as follows: 0.4-0.7, 0.0-1.0, 0.4-1.1, 0.6-0.9, and 0.1-0.4eV. A mean absolute deviation of 0.3eV was achieved if we compare only to the closest experiment. We found that the sensitivity of computed BEs to different model shapes depends on systems: graphene, sensitive; C3N, weak; and h-BN, very weak. This can be attributed to their more or less delocalized π electrons in this series. For this reason, a larger cluster size is required for graphene than the other two to reproduce fine structures in XAS. The general profile of XAS shows weak dependence on model shape. Our calculations provide optimal parameters and accuracy estimations that are useful for x-ray spectral simulations of general graphene-like 2D materials.

Theoretical Study on the Structure and Spectral Properties of Several Classical and Non-Classical C76 Isomers and Their Newly Synthesized Derivatives.

X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra, as well as the ground-state electronic/geometrical structures of the newly discovered two non-classical isomers C2-C76(NC2) and C1-C76(NC3) with their derivatives C2-C76(NC2)(CF3)14 and C1-C76(NC3)Cl24, as well as the non-IPR(isolated pentagon rule) isomer C1-#17418C76 with its embedded metal fullerene U@C1-#17418C76 have been calculated at the density functional theory (DFT) level. The electronic structure after chlorination is significantly different in the simulated X-ray spectrum. Both XPS and NEXAFS spectra reflect obvious isomer dependence, indicating that the "fingerprint" in X-ray spectroscopy can provide an effective means for the identification of the above-mentioned fullerene isomers. Time-dependent DFT was used to simulate the ultraviolet-visible absorption spectrum of U@C1-#17418C76. The calculated results are in good agreement with the experimental consequence. This work reveals that theoretically simulated X-ray and UV-vis spectroscopy techniques can provide valuable information to help researchers explore the electronic structure of fullerenes and the identification of isomers in future experimental and theoretical fields.

Structural and Spectral Properties of a Nonclassical C66 Isomer with Its Hydrogenated Derivative C66H4 in Theory.

X-ray photoelectron and near-edge X-ray absorption fine structure (NEXAFS) spectra, as well as the ground-state electronic/geometrical structures of a newly discovered nonclassical isomer C2v-C66(NC), and two classical fullerene isomers C2-#4466C66 and Cs-#4169C66 with their hydrogenated derivatives [C2v-C66H4(NC), C2-#4466C66H4, and Cs-#4169C66H4] have been calculated at the density functional theory (DFT) level. Significant differences were observed in the electronic structures and simulated X-ray spectra after hydrogenation. Simultaneously, both X-ray photoelectron and NEXAFS spectra reflected conspicuous isomer dependence, indicating that the “fingerprints” in the X-ray spectra can offer an effective method for identifying the above-mentioned fullerene isomers. The simulated ultraviolet–visible (UV–vis) absorption spectroscopy of C2v-C66H4(NC) has also been generated by means of the time-dependent DFT method, and the calculations are well consistent with the experimental results. Consequently, this work reveals that X-ray and UV–vis spectroscopy techniques can provide valuable information to help researchers explore the fullerene electronic structure and isomer identification on the future experimental and theoretical fullerene domains.

Mathematical estimation of half-value layer thicknesses.

ObjectiveThe objective of this article is to introduce a simplified and swift method to satisfactorily estimate the half‐value layers (HVL), quarter‐value layer (QVL), and tenth‐value layer (TVL) from the x‐ray spectra emitted by any diagnostic radiology or kV radiotherapy x‐ray tubes.MethodsA CdTe x‐ray and Gamma detector (X‐123 CdTe, AmpTek Inc.) is used to measure the x‐ray spectra at four different x‐ray energies (low, mid, high energy x‐rays) with different external filtering. The software “SpekCalc GUI” (Developed in McGill University, Montreal, Canada) is also used to obtain the simulated x‐ray spectra. Both measured and simulated spectra are used to compute the HVL thicknesses of Aluminum by a mathematical method presented in this article. Next, the HVL thicknesses for corresponding tube potentials are also measured by calibrated ionization chamber and varying thicknesses of aluminum plates. Finally, the computed and measured HVL, QVL, and TVL thicknesses are compared to evaluate the efficacy of the presented method.ResultsThe results show acceptable concordance between computed and measured quantities. The disagreement rates between measured HVL and the values derived mathematically from the x‐ray spectra are 10 to 90 micrometers of Aluminum at tube potentials of 31 kV to 120 kV. As it is shown, a negligible discrepancy is observed between the analytical estimation and the experimental assessments.ConclusionThe HVL is an essential component in the evaluation of the quality of an x‐ray beam. However, its measurement could occasionally be challenging, time‐consuming, or uncertain due to some technical difficulties. Although the scope of this study is not to undermine the value of conventional and widely accepted practice to determine the HVL thickness, the introduced method provides the fast, more convenient, and comparably reliable technique to estimate the HVL, QVL, and TVL by employing the given x‐ray spectrum.

X-ray Spectroscopy Fingerprints of Pristine and Functionalized Graphene.

In this work, we demonstrate how to identify and characterize the atomic structure of pristine and functionalized graphene materials from a combination of computational simulation of X-ray spectra, on the one hand, and computer-aided interpretation of experimental spectra, on the other. Despite the enormous scientific and industrial interest, the precise structure of these 2D materials remains under debate. As we show in this study, a wide range of model structures from pristine to heavily oxidized graphene can be studied and understood with the same approach. We move systematically from pristine to highly oxidized and defective computational models, and we compare the simulation results with experimental data. Comparison with experiments is valuable also the other way around; this method allows us to verify that the simulated models are close to the real samples, which in turn makes simulated structures amenable to several computational experiments. Our results provide ab initio semiquantitative information and a new platform for extended insight into the structure and chemical composition of graphene-based materials.

SEM-EDS nanoanalysis of mineral composite materials: A Monte Carlo approach

A quantitative determination of chemical and mineral composition at the nanoscale is nowadays fundamental for the knowledge of properties of innovative composite materials. Scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDS) is one of the most commonly employed spatially-resolved analytical methods, because of its versatility and great potential for nano-analysis. However, because of both complex architecture, texture and reduced grain sizes (micro-to-nano) in many composites, to avoid analytical errors, several effects related to electron and X-ray transport in solids must be considered. In the present work, a Monte Carlo SEM-EDS simulation approach is proposed and applied to selected micro-nanosized architectures usually found in composites. The effects of both micro-nanometric grain sizes (100 nm−20 μm) and basic geometrical shapes (cubic, hemicylindrical) of embedded features in the sample matrix (a metal matrix and a glass fibre-reinforced cementitious composite), together with a realistic SEM-EDS setup, were studied. The results evidenced a high dependence of the simulated X-ray spectra versus particles thickness and shape, beam energy and sample-to-detector configuration, which directly affect a correct analytical characterization. The Monte Carlo simulation allowed to investigate and control the physical phenomena affecting the measurement and eventually to determine the optimal SEM-EDS parameters.

Density Functional Theory Based Methods for the Calculation of X-ray Spectroscopy.

The availability of new light sources combined with the realization of the unique capabilities of spectroscopy in the X-ray region has driven tremendous advances in the field of X-ray spectroscopy. Currently, these techniques are emerging as powerful analytical tools for the study of a wide range of problems encompassing liquids, materials, and biological systems. Time-resolved measurements add a further dimension to X-ray spectroscopy, opening up the potential to resolve ultrafast chemical processes at an atomic level. X-ray spectroscopy encompasses a range of techniques which provide complementary information, and these include X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and resonant inelastic X-ray scattering (RIXS). In many studies, the interpretation of the experimental data relies upon calculations to enable the nature of the underlying molecular structure, electronic structure, and bonding to be revealed. Density functional theory (DFT) based methods are some of the most widely used methods for the simulation of X-ray spectra. In this Account, we focus on our recent contributions to the simulation of a range of X-ray spectroscopic techniques using DFT and linear-response time-dependent density functional theory (TDDFT) and show how these methods can provide a computational toolkit for the simulation of X-ray spectroscopy. The importance of the exchange-correlation functional for the calculation of XAS is discussed, and the introduction of short-range corrected functionals is described. The application of these calculations to study large systems through the use of efficient implementations of TDDFT will be highlighted, with the use of these methods illustrated through studies of ionic liquids and transition metal complexes. The extension of TDDFT to calculate XES through the use of a reference determinant for the core-ionized state will be described, and the factors that affect the accuracy of the computed spectra discussed. The application of these approaches will be illustrated through the study of a range of organic molecules and transition metal complexes, which also show how going beyond the dipole approximation in determining the transition intensities can be critical. The application of these approaches to the simulation of the RIXS spectrum of water will also be described, highlighting how ultrafast dynamics on the femtoscale time scale are evident in the measured spectra. In these calculations, the description of the core-ionized and core-excited states becomes increasingly important, and the role of the basis set in accurately describing these states will be explored.

Influence of Internal Structure of Semiconductor Detector on Spectrum of X-Rays Induced by Tritium Beta Rays

Nondestructive measurement of tritium (T) content in solid materials is important for safe and cost-effective disposal of contaminated wastes, and beta-ray induced X-ray spectrometry (BIXS) has been developed for this purpose. A common way to obtain depth profiles of T in solids using BIXS is to perform simulation of X-ray spectra for assumed depth profiles and find a profile giving the best agreement with observation. A detailed understanding of attenuation of low-energy X-rays (≤18.6 keV) by detector components such as a window material is required for interpretation of measured spectra and simulation. In this study, BIXS spectra of a tungsten reference sample with known T depth profile were measured using two different semiconductor detectors and simulated using the Monte Carlo simulation toolkit Geant4. In the low-energy region (<2 keV), the difference in internal structure resulted in a noticeable difference in the BIXS spectra. The disagreement between the measured and the simulated spectra was also significant at <2 keV. Nevertheless, at >2 keV, the BIXS spectra were insensitive to the internal structure of the detector, and the simulated spectra agreed well with the measured ones. The mechanism underlying the difference in the low-energy region was discussed.

In-situ observation of structural and chemical transitions in B4C based layered systems

In the context of multilayer based X-ray optics developments, thin layered systems of C/[Pt/B4C] multilayers and C/Pt/B4C/Cr stacks with variable cap layer thicknesses were deposited on Si wafers using DC magnetron sputtering. The samples were studied with in-situ X-ray reflectivity techniques during annealing in air up to temperatures of 300 °C. Simulated X-ray spectra of B4C/Cr reveal a considerable thickness loss of the B4C layer at elevated temperatures. The effect is amplified and accelerated when a thin Pt top layer is added but attenuated and slowed down by an additional C cap layer. Energy dispersive X-ray spectroscopy data indicate the overall depletion of B in samples after the annealing process. In-depth studies using X-ray photoelectron spectroscopy techniques show clear evidence of chemical modifications in the original B4C layer and confirm the structural modifications derived from the X-ray reflectivity data. This study demonstrates the catalyzing role of Pt in the degradation of B4C based layered structures in air and the potential protective function of C cap layers.

Development of broadband x-ray radiography for diagnosing magnetically driven cylindrically compressed matter

Experiments and modeling of x-ray radiography of millimeter diameter solid Al wires with laser-produced broadband x rays are reported. Experiments were performed using the 50-TW Leopard short-pulse laser in a laser and pulsed power chamber at the Nevada Terawatt Facility. To characterize broadband x rays and demonstrate a radiographic capability, bremsstrahlung, escaping electrons, and radiograph images of Al wires were simultaneously measured. The angularly resolved x-ray spectra are modeled by comparing measured bremsstrahlung signals in the range between 10 and ∼500 keV with hybrid particle-in-cell simulations. Transmission of Al wires from the radiograph images is further simulated with a Monte Carlo code. The measured transmission profiles of Al wires with three different diameters agree with calculations when a simulated x-ray spectrum composed of line emissions and bremsstrahlung is used with a source size of 600 ± 200 μm. Transmission calculations with only 22 keV Ag Kα or an exponential x-ray spectrum do not reproduce the measurement, suggesting that the accurate determination of an x-ray source spectrum, as well as the inclusion of the photon sensitivity of the detector, is critical in transmission calculations to infer the density of an object. The laser-based broadband x-ray radiography that was developed has been successfully implemented in a pulsed power chamber for future laser-pulsed-power coupled experiments.

7.1 keV sterile neutrino dark matter constraints from a deepChandraX-ray observation of the Galactic bulge Limiting Window

Context. An unidentified emission line at 3.55 keV was recently detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1 keV sterile neutrinos, which have been proposed as a dark matter (DM) candidate.Aims. We aim to further constrain the line strength and its implied mixing angle under the assumption that all DM is made of sterile neutrinos.Methods. The X-ray observations of the Limiting Window (LW) towards the Galactic bulge (GB) offer a unique dataset for exploring DM lines. We characterise the systematic uncertainties of the observation and the fitted models with simulated X-ray spectra. In addition, we discuss uncertainties of indirect DM column density constraints towards the GB to understand systematic uncertainties in the assumed DM mass in the field of view of the observation.Results. We find tight constraints on the allowed flux for an additional line at 3.55 keV with a positive (∼1.5σ) best fit valueFX3.55 keV ≈ (4.5 ± 3.5) × 10−7 cts cm−2 s−1. This would translate into a mixing angle of sin2(2Θ) ≈ (2.3 ± 1.8) × 10−11which, while consistent with some recent results, is in tension with earlier detections.Conclusions. We used a very deep dataset with well understood systematic uncertainties to derive tight constraints on the mixing angle of a 7.1 keV sterile neutrino DM candidate. The results highlight that the inner Milky Way will be a good target for DM searches with upcoming missions like eROSITA, XRISM, and ATHENA.

Monte Carlo simulation of X-ray spectra produced by Linac

This study was conducted to determine the intensity distribution of X-ray energy spectrum of that produced by Linear Accelerator (Linac) with tungsten target (W). The x-ray spectra on the space behind of target is calculated through the simulation method using Monte Carlo N-Particle eXtended version software (MCNPX). Linac is simulated with acceleration voltage 6 MV up to 15 MV using tungsten metal target (W). Based on the simulation of electron source accelerated, X-rays generated mostly (40-75) % are X-rays with energy of 1 MeV to 2 MeV, whereas the intensity of X-rays with energies fit the energies of the shooter’s electrons is very small (0.03 -0.340)%. It was indicated that the energy spectra dominated in the 1 MeV to 2 MeV than maximum energy in the x-ray spectrum range along the energy variation of Linac radiotherapy simulation. In addition, also found electrons about 2.24% to 5.67% compared to the intensity of X-rays, so as to increase the equivalent dose in the patient’s tissue later. This information can be used for the manufacture of low energy range filter design that dominate the spectrum and consideration of radiation protection efforts.