Search

Copyright of Momento: Revista de Física is the property of Universidad Nacional de Colombia, Departamento de Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The X-ray spectra of L-shell transitions in Neon-like Xenon ion (Xe44+) have been precisely measured at the Shanghai Electron-Beam Ion Trap using a high-resolution crystal spectrometer. Focusing on the line-intensity ratio of the 3F {2p6-(2p51/23s1/2)J=1} and 3D {2p6-(2p53/23d5/2)J=1} lines (3F/3D), our measurements have achieved remarkable precision improvements over the previous studies. These spectra have been simulated using the collisional-radiative model (CRM) within the Flexible Atomic Code, showing good agreement with the measurements. The previously reported discrepancies, approximately ranging from 10% to 20%, have been significantly reduced in this work to below 1.4% for electron-beam energies exceeding 6 keV and to around 7% for lower energies. Furthermore, our analysis of population fluxes of the involved levels reveals a very high sensitivity of the 3F line to radiation cascades. This suggests that the current CRM, which conventionally excludes interionic population transfer processes, may underestimate the population of the upper level of the 3F line and the cascade-related higher levels, thus explaining the remaining discrepancies. These findings provide a solid foundation for further minimizing these discrepancies and are crucial for understanding the atomic structure and plasma model of these ions. [ABSTRACT FROM AUTHOR]

The spectra and global distributions of the X-ray emissions generated by the solar wind charge-exchange (SWCX) process in the terrestrial magnetosheath are investigated based on a global hybrid model and a global geocoronal hydrogen model. Solar wind O6+ ions, which are the primary charge state for oxygen ions in solar wind, are considered. The line emissivity of the charge-exchange-borne O5+ ions is calculated by the Spectral Analysis System for Astrophysical and Laboratory (SASAL). It is found that the emission lines from O5+ range from 105.607 to 118.291 eV with a strong line at 107.047 eV. We then simulate the magnetosheath X-ray emission intensity distributions with a virtual camera at two positions of the north pole and dusk at six stages during the passing of a perpendicular interplanetary shock combined with a tangential discontinuity structure through the Earth's magnetosphere. During this process, the X-ray emission intensity increases with time, and the maximum value is 27.11 keV cm−2 s−1 sr−1 on the dayside, which is 4.5 times that before the solar wind structure reached the Earth. A clear shock structure can be seen in the magnetosheath and moves earthward. The maximum emission intensity seen at dusk is always higher than that seen at the north pole. [ABSTRACT FROM AUTHOR]

Knowledge of the photon spectrum emitted from an x-ray tube is frequently needed in imaging and dosimetry contexts.As the spectrum characteristics are influenced by several parameters and routine measurement of a spectrum is often impractical, a variety of software programs have been developed over the decades for convenient calculations.SpekPy is a state-of-the-art software package containing several spectrum models, and was created to estimate photon spectra originating from x-ray tubes using a small set of input parameters (e.g., anode material,anode angle,tube potential, filtration, etc.).SpekPy is distributed as a Python toolkit and is available free of charge.The toolkit does,however, lack a graphical user interface and a user is required to write a Python script to make use of it. In this work this limitation is addressed by introducing a web application called SpekPy Web: a graphical user interface together with an application programmable interface (API). These developments both make the SpekPy spectrummodels accessible to a broader set of users and increases the ease of use for existing users. SpekPy Web is hosted at: https://spekpy.smile.ki.se. The functionality of the software is demonstrated, using its API, by estimating first half-value layers (HVLs) for 15 standard beam qualities from the International Bureau of Weights and Measures (BIPM). The estimated HVLs were found to all be within 3.5% agreement when compared to experimental values, with an average calculation time of 2.5 s per spectrum. [ABSTRACT FROM AUTHOR]

Photoionized plasma is an important form of plasma in the universe, which is produced by some high-energy celestial bodies emitting strong radiation fields to irradiate the surrounding thin plasma. With the development of high energy density physics, the photoionized plasma can be produced in laboratory. In 2009, Fujioka et aL used the GEKKO-XII laser facility to produce photoionzed Si plasma, and observed X-ray spectYum similar to that in astrophysical environment. This paper reviews the main theoretical simulation results for the experimental X-ray spectrum since this photoionization experiment, and proposes the future research direction on the photoionized plasma. This review aims to provide a reference for researchers in related fields and deepen their understanding of the physical mechanism of photoionized plasma. [ABSTRACT FROM AUTHOR]

A digital model of a grazing-incidence X-ray spectrograph and methods for reconstruction of soft X-ray spectra of a Z-pinch plasma at the Angara-5-1 facility in the 2–40 nm range have been developed. The main problems hindering reliable qualitative and quantitative reconstruction of the initial Z-pinch X-ray spectra are the superposition of signals from different diffraction orders and the complex form of the device instrumental function. Two techniques for reconstructing the spectrum are presented. In the first one, a digital model of the spectrograph was developed in the Geant4 Monte Carlo simulation toolkit, taking into account the geometry of the experiment and the processes of interaction of X-ray radiation with a diffraction grating. In this model, taking into account the specific shape of the groove profile of the diffraction grating and the differential method for solving the diffraction problem, the X-ray intensity distribution in different diffraction orders depending on the wavelength is calculated. Using the developed model of the spectrograph, its instrumental function was calculated. The second technique does not use a specific grating groove shape, but, based on the analysis of calibration spectrograms, it constructs a dispersion relation and allows one to reconstruct the spectrum. At the end of the work, the results of reconstruction by the first and second techniques are compared and fairly good agreement between the spectra obtained by different techniques is shown. [ABSTRACT FROM AUTHOR]

The X-ray spectra of L-shell transitions in Neon-like Xenon ion (Xe44+) have been precisely measured at the Shanghai Electron-Beam Ion Trap using a high-resolution crystal spectrometer. Focusing on the line-intensity ratio of the 3F {2p6-(2p51/23s1/2)J=1} and 3D {2p6-(2p53/23d5/2)J=1} lines (3F/3D), our measurements have achieved remarkable precision improvements over the previous studies. These spectra have been simulated using the collisional-radiative model (CRM) within the Flexible Atomic Code, showing good agreement with the measurements. The previously reported discrepancies, approximately ranging from 10% to 20%, have been significantly reduced in this work to below 1.4% for electron-beam energies exceeding 6 keV and to around 7% for lower energies. Furthermore, our analysis of population fluxes of the involved levels reveals a very high sensitivity of the 3F line to radiation cascades. This suggests that the current CRM, which conventionally excludes interionic population transfer processes, may underestimate the population of the upper level of the 3F line and the cascade-related higher levels, thus explaining the remaining discrepancies. These findings provide a solid foundation for further minimizing these discrepancies and are crucial for understanding the atomic structure and plasma model of these ions.

Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 1013 W cm−2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 μm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances I0 ranging from 7.3 × 1013 W cm−2 up to 3.0 × 1014 W cm−2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 1014 W cm−2. [ABSTRACT FROM AUTHOR]

It is shown that combined diffraction and absorption filtration of a polychromatic X-ray spectrum allows spectral bands tunable in energy and relative width to be separated. In the energy range E < 30–35 keV, the spectral valley is formed by passing a polychromatic beam through a plate of the highly oriented pyrolytic graphite mosaic crystal ≈0.5–1 mm thick under the Bragg condition of diffraction. The filtration band width is extended by placing two or more plates at different diffraction angles. In the energy range E > 35–40 keV, filtration is performed by a selectively absorbing filter that contains a chemical element with the photoabsorption K-jump energy in this region of the spectrum. The results can be used in medical X-ray diagnostics and X-ray spectrometry. [ABSTRACT FROM AUTHOR]

Over the last several decades, food irradiation technology has been proven neither to reduce the nutritional value of foods more than other preservation technologies, nor to make foods radioactive or dangerous to eat. Furthermore, food irradiation is a non-thermal food processing technology that helps preserve more heat sensitive nutrients than those found in thermally processed foods. Conventional food irradiation technologies, including X-ray, electron beam and high energy X-ray, have certain limitations and drawbacks, such as involving radioactive isotopes, low penetration ability, and economical unfeasibility, respectively. Owing to the recent developments in instrumentation technology, more compact and cheaper tabletop low-energy X-ray sources have become available. The generation of low-energy X-ray, unlike X-ray, does not involve radioactive isotopes and the cost is lower than high energy X-ray. Furthermore, low-energy X-ray possesses unique advantages, i.e., high linear energy transfer (LET) value and high relative biological effect (RBE) value. The advantages allow low-energy X-ray irradiation to provide a higher microbial inactivation efficacy than X-ray and high energy X-ray irradiation. In the last few years, various applications reported in the literature indicate that low-energy X-ray irradiation has a great potential to become an alternative food preservation technique. This chapter discusses the technical advances of low-energy X-ray irradiation, microbial inactivation mechanism, factors influencing its efficiency, current applications, consumer acceptance, and limitations. [ABSTRACT FROM AUTHOR]

Objectives: Thanks to its lack of allergic reactions and renal toxicity, CO2represents an alternative to iodine as a contrast medium for peripheral subtraction angiography. Since CO2has a lower and negative contrast than iodine, postprocessing DSA and stacking are mandatory. So, it seems that higher doses than traditional iodine angiography are required. We addressed the dosimetric aspects of CO2angiography for two different commercial DSA-apparatus. Materials and Methods: Two different radiological suites were analyzed by recreating the same setup on all the apparatuses: we used a PMMA slabs phantom with a MPD Barracuda dosimeter on its side to collect all radiological parameters. Results: Results show that the irradiation parameters were left completely unchanged between the traditional and CO2angiographic programs. Conclusions: This leads to thinking that these CO2protocols do not operate on the X-ray emission, but only differ on image manipulation. The possibility of improvements by changing radiological parameters are still not explored and really promising.

Objective: The 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. Methods: A 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. Results: The 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. Conclusion: The 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. [ABSTRACT FROM AUTHOR]

The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a slit spectrograph designed to fly on a sounding-rocket and to observe the Sun in soft X-rays (SXRs) to determine the frequency of coronal heating events. The MaGIXS wavelength range (≈ 0.6 – 2.5 nm) has a significant number of diagnostic lines formed at coronal temperatures, but developing SXR instrumentation presents several challenges, including how to efficiently perform context imaging. A slitjaw image is required for pointing the instrument during flight and for co-alignment with coordinated data sets after flight, but operating in the SXR regime implies that a simple normal-incidence optical system could not be employed to image the same wavelength range as the spectrograph. Therefore, to avoid the complexity of additional grazing-incidence optics, the MaGIXS slitjaw system is designed to image in the extreme ultraviolet (EUV) between roughly 20 – 80 nm. The temperature sensitivity of this EUV bandpass will observe complementary features visible to the MaGIXS instrument. The image on the slitjaw is then converted, via a phosphor coating, to readily detectable visible light. Presented here is the design, implementation, and characterization of the MaGIXS slitjaw imaging system. The slitjaw instrument is equipped with an entrance filter that passes EUV light, along with X-rays, onto the slit, exciting a fluorescent coating and causing it to emit in the visible. This visible light can then be imaged by a simple implementation of commercial off-the-shelf (COTS) optics and low-light camera. Such a design greatly reduces the complexity of implementing and testing the slitjaw imager for an X-ray instrument system and will accomplish the pointing and co-alignment requirements for MaGIXS. [ABSTRACT FROM AUTHOR]

The energy spectrum of an X-ray tube plays an important role in computed tomography (CT), and is often estimated from physical measurement of dedicated phantoms. Usually, this estimation problem is reduced to solving a system of linear equations, which is generally ill-conditioned. In this paper, we optimize a phantom design to find the most effective combinations of thicknesses for different materials. First, we analyze the ill-posedness of the energy spectrum inversion when the number of unknown variables (N) and measurements (M) are equal, and show the condition number of the system matrix increases exponentially with N if the transmission thicknesses are linearly changed. Then, we present a genetic optimization algorithm to minimize the condition number of the system matrix in a general case (M < N) with respect to the selection of thicknesses and types of phantom materials. Finally, in the simulation with Poisson noise we study the accuracy of the spectrum estimation using the expectation-maximum algorithm. Our results indicate that the proposed method allows high-quality spectrum estimation, and the number of measurements is reduced over two thirds of that required by the widely-used method using a phantom with linearly-changed thicknesses.

Cylindrical reflex triodes (CRTs) driven by a pulsed power generator can produce relatively low-endpoint X-ray spectra (~250 keV) that can be suitable for certain radiation–matter interaction studies. CRTs have several advantages over other reflex triode configurations, the most significant being the ability to operate multiple concentric CRTs, connected either in parallel or in series. Such configurations can result in increased X-ray output without increasing the endpoint or changing the pulsed-power generator. This article describes results from, and modeling of, experiments employing a single CRT and two CRTs in a series configuration. The modeling includes an analytic, physics-based model of CRT electrical operation; measured and calculated radiation distributions and spectra; and predicted effects of several configuration variations. [ABSTRACT FROM AUTHOR]

Results are presented from investigating active and drainage layers of composite films (membranes) UPM-50 and UPM-100 before and after exposure to transmembrane pressure by means of IR spectra of reflection, X-ray scattering, and raster electron microscopy. It is found that changes in the IR spectrum of the working sample are caused by the destruction of weak bonds of C=O···H–N amide fragments of the polysulfonamide film. A drop in (C=O) vibration frequency ν by Δν = 20 cm−1 indicates redistribution of the electron density between C=O-groups and benzene rings as a result of the inductive effect of coupling, which results in the formation of charged functional groups CO−. The presence of CO– groups fragments a new supramolecular structure whose stability due to the dipole–dipole interaction of carbonyl anions. X-ray scattering of the initial and working samples in the 10°–35° range of angles 2θ is determined by three intense reflections at angles 2θ ~ 17.23°, 22.24°, 25.41° from crystallographic planes ((010), (100), and (110)) corresponding to the crystalline structure of lavsan (polyethylene terephthalate). A comparative analysis of the reduced intensities of reflections from crystallographic planes (010), (100) and the sizes of lamellas indicates that transmembrane pressure initiates conformational rearrangement of crystallites with crystallographic axis b oriented parallel to the film plane. [ABSTRACT FROM AUTHOR]

Objective. In this work, we aim to propose an accurate and robust spectrum estimation method by synergistically combining x-ray imaging physics with a convolutional neural network (CNN). Approach. The approach relies on transmission measurements, and the estimated spectrum is formulated as a convolutional summation of a few model spectra generated using Monte Carlo simulation. The difference between the actual and estimated projections is utilized as the loss function to train the network. We contrasted this approach with the weighted sums of model spectra approach previously proposed. Comprehensive studies were performed to demonstrate the robustness and accuracy of the proposed approach in various scenarios. Main results. The results show the desirable accuracy of the CNN-based method for spectrum estimation. The ME and NRMSE were -0.021 keV and 3.04% for 80 kVp, and 0.006 keV and 4.44% for 100 kVp, superior to the previous approach. The robustness test and experimental study also demonstrated superior performances. The CNN-based approach yielded remarkably consistent results in phantoms with various material combinations, and the CNN-based approach was robust concerning spectrum generators and calibration phantoms. Significance . We proposed a method for estimating the real spectrum by integrating a deep learning model with real imaging physics. The results demonstrated that this method was accurate and robust in estimating the spectrum, and it is potentially helpful for broad x-ray imaging tasks., (© 2024 Institute of Physics and Engineering in Medicine.)

Lab-based X-ray computed tomography (XCT) systems use X-ray sources that emit a polychromatic X-ray spectrum and detectors that do not detect all X-ray photons with the same efficiency. A consequence of using a polychromatic X-ray source is that beam hardening artefacts may be present in the reconstructed data, and the presence of such artefacts can degrade XCT image quality and affect quantitative analysis. If the product of the X-ray spectrum and the quantum detection efficiency (QDE) of the detector are known, alongside the material of the scanned object, then beam hardening artefacts can be corrected algorithmically. In this work, a method for estimating the product of the X-ray spectrum and the detector’s QDE is offered. The method approximates the product of the X-ray spectrum and the QDE as a Bézier curve, which requires only eight fitting parameters to be estimated. It is shown experimentally and through simulation that Bézier curves can be used to accurately simulate polychromatic attenuation and hence be used to correct beam hardening artefacts. The proposed method is tested using measured attenuation data and then used to calculate a beam hardening correction for an aluminium workpiece; the beam hardening correction leads to an increase in the contrast-to-noise ratio of the XCT data by 41% and the removal of cupping artefacts. Deriving beam hardening corrections in this manner is more versatile than using conventional material-specific step wedges.

X-ray imaging crystal spectrometers with high spectral and spatial resolutions are the important diagnostic tools for acquiring high-quality plasma information in the study of laser–matter interactions. In this paper we propose a new multi-channel imaging crystal spectrometer with coupling X-ray framing camera to record the dynamic evolution of a laser-induced plasma: a four-channel imaging mica crystal spectrometer with a spatial resolution of 40–60 μm for diagnosing the aluminum (Al) plasma targets was developed. Calibration experiments revealed that the spectral resolution is higher than 1700 at Al K α3 characteristic lines (1496.4eV). Further, we established an aiming method based on the positioning ball and two monitoring CCDs. The optical design, mechanical design, and experimental measurements of the four-channel imaging mica crystal spectrometer are discussed. [ABSTRACT FROM AUTHOR]

Introduction One of the best methods in the diagnosis and control of breast cancer is mammography. The importance of mammography is directly related to its value in the detection of breast cancer in the early stages, which leads to a more effective treatment. The purpose of this article was to calculate the X-ray spectrum in a mammography system with Monte Carlo codes, including MCNPX and MCNP5. Materials and Methods The device, simulated using the MCNP code, was Planmed Nuance digital mammography device (Planmed Oy, Finland), equipped with an amorphous selenium detector. Different anode/filter materials, such as molybdenum-rhodium (Mo-Rh), molybdenum-molybdenum (Mo-Mo), tungsten-tin (W-Sn), tungsten-silver (W-Ag), tungsten-palladium (W-Pd), tungsten-aluminum (W-Al), tungsten-molybdenum (W-Mo), molybdenum-aluminum (Mo-Al), tungsten-rhodium (W-Rh), rhodium-aluminum (Rh-Al), and rhodium-rhodium (Rh-Rh), were simulated in this study. The voltage range of the X-ray tube was between 24 and 34 kV with a 2 kV interval. Results The charts of changing photon flux versus energy were plotted for different types of anode-filter combinations. The comparison with the findings reported by others indicated acceptable consistency. Also, the X-ray spectra, obtained from MCNP5 and MCNPX codes for W-Ag and W-Rh combinations, were compared. We compared the present results with the reported data of MCNP4C and IPEM report No. 78 for Mo-Mo, Mo-Rh, and W-Al combinations. Conclusion The MCNPX calculation outcomes showed acceptable results in a low-energy X-ray beam range (10-35 keV). The obtained simulated spectra for different anode/filter combinations were in good conformity with the finding of previous research.

Purpose: We study the problem of spectrum estimation from transmission data of a known phantom. The goal is to reconstruct an x‐ray spectrum that can accurately model the x‐ray transmission curves and reflects a realistic shape of the typical energy spectra of the CT system. Methods: Spectrum estimation is posed as an optimization problem with x‐ray spectrum as unknown variables, and a Kullback–Leibler (KL)‐divergence constraint is employed to incorporate prior knowledge of the spectrum and enhance numerical stability of the estimation process. The formulated constrained optimization problem is convex and can be solved efficiently by use of the exponentiated‐gradient (EG) algorithm. We demonstrate the effectiveness of the proposed approach on the simulated and experimental data. The comparison to the expectation–maximization (EM) method is also discussed. Results: In simulations, the proposed algorithm is seen to yield x‐ray spectra that closely match the ground truth and represent the attenuation process of x‐ray photons in materials, both included and not included in the estimation process. In experiments, the calculated transmission curve is in good agreement with the measured transmission curve, and the estimated spectra exhibits physically realistic looking shapes. The results further show the comparable performance between the proposed optimization‐based approach and EM. Conclusions: Our formulation of a constrained optimization provides an interpretable and flexible framework for spectrum estimation. Moreover, a KL‐divergence constraint can include a prior spectrum and appears to capture important features of x‐ray spectrum, allowing accurate and robust estimation of x‐ray spectrum in CT imaging. [ABSTRACT FROM AUTHOR]

Facing the technical problem of pulse distortion caused by frequent resetting in the latest high‐performance silicon drift detectors, which work under high‐counting‐rate conditions, a method has been used to remove false peaks in order to obtain a precise X‐ray spectrum, the essence of which eliminates distorted pulses. Aiming at solving the problem of counting‐loss generated by eliminating distorted pulses, this paper proposes an improved method of pulse repairing. A 238Pu source with activity of 10 mCi was used as the measurement object, and the energy spectrum obtained by the pulse repairing method was compared with that obtained by the pulse elimination method. The ten‐measurement results show that the pulse repairing method can correct the counting‐loss caused by the pulse elimination method and increase peak area, which is of great significance for obtaining a precise X‐ray energy spectrum. A method is proposed to correct for the counting loss generated by removing distorted pulses in X‐ray spectra. The count rate obtained by the pulse repair method is increased by about 3% compared with that obtained by the pulse elimination method, and the sum of the peak area obtained by the pulse repairing method is increased by about 2.7% compared with that obtained by the pulse elimination method. [ABSTRACT FROM AUTHOR]

L-shell X-rays of 48 Cd and 49 In have been measured for the bombardment of protons in the energy range 75–250 keV in steps of 25 keV. The individual Lι, Lα, Lβ, Lγ and total L X-ray production cross sections were extracted from the yield. The results were compared with theoretical predictions of PWBA, ECPSSR and ECUSAR, as well as with experimental results of other authors. Good agreements were observed for our data with others and ECPSSR or ECUSAR calculations. The influence of using different atomic parameter databases is also discussed. [ABSTRACT FROM AUTHOR]

A novel X-ray spectrometer is designed to diagnose the different conditions in plasmas. It can provide both X-ray spectroscopy and plasma image information simultaneously. Two pairs of elliptical crystal analyzers are used to measure the X-ray spectroscopy in the range of 2–20 keV. The pinhole imaging system coupled with gated micro-channel plate(MCP) detectors are developed, which allows 20 images to be collected in a single individual experiment. The experiments of measuring spectra were conducted at “Shenguang-II upgraded laser” in China Academy of Engineering Physics to demonstrate the utility of the spectrometer. The X-ray spectroscopy information was obtained by the image plate(IP). The hot spot imaging experiments were carried out at “Shenguang-III prototype facility”. We have obtained the hot sport images with the spectrometer, and the signal to noise ratio of 30 ∼ 40 is observed. [ABSTRACT FROM AUTHOR]

Pulse pile-up (PPU) is an always present effect which introduces a distortion into the spectrum measured with radiation detectors and that worsen with the increasing emission rate of the radiation source. It is fully ascribable to the pulse handling circuitry of the detector and it is not comprised in the detector response function which is well explained by a physical model. The PPU changes both the number and the height of the recorded pulses, which are related, respectively, with the number of detected particles and their energy. In the present work, it is derived a first principles balance equation for second order PPU to obtain a post-processing correction to apply to X-ray measurements. The balance equation is solved for the particular case of rectangular pulse shape using a deterministic iterative procedure for which it will be shown the convergence. The proposed method, deterministic rectangular PPU (DRPPU), requires minimum amount of information and, as example, it is applied to a solid state Si detector with active or off-line PPU suppression circuitry. A comparison shows that the results obtained with this fast and simple approach are comparable to those from the more sophisticated procedure using precise detector pulse shapes. [ABSTRACT FROM AUTHOR]

The aim of our study is to develop a novel material identification method based on a photon counting technique, in which the incident and penetrating X-ray spectra are analyzed. Dividing a 40 kV X-ray spectra into two energy regions, the corresponding linear attenuation coefficients are derived. We can identify the materials precisely using the relationship between atomic number and linear attenuation coefficient through the correction of the beam hardening effect of the X-ray spectra. [ABSTRACT FROM AUTHOR]

This paper focuses mainly on the generation of X-rays in the X-ray tubes and their utilization in imaging applications. In this work, the Geant4 Monte Carlo simulation toolkit was used to develop an application for simulating the production of X-rays in X-ray tubes. This Geant4-based Monte Carlo application generates X-ray spectra depending on anode angle, tube voltage, filter and anode material. In addition to X-ray spectra, G4XRTube can be used, for instance, for the prediction of half-value layer (HVL) and investigation of anode heel effect. The utilization of G4XRTube can also be extended to include other fields such as radiation protection, shielding, dosimetry and investigation of the performance of X-ray tubes and detectors. The results obtained in this work with G4XRTube were validated against existing data in the literature. Specifically, we compared our results with experimental literature data and TASMICS, SpekCalc, and SpekPy codes. The comparison shows a good agreement between G4XRTube results and other data. • A Geant4-based application was developed for X-ray tube simulation. • Validation of X-ray spectra against existing data and software in the literature. • Calculation of Half-Value Layer and mean energy of the X-ray beam. • Estimation of percent depth dose in water phantom. • Investigation of anode heel effect and spatial distribution of X-rays. [ABSTRACT FROM AUTHOR]

Introduction One of the best methods in the diagnosis and control of breast cancer is mammography. The importance of mammography is directly related to its value in the detection of breast cancer in the early stages, which leads to a more effective treatment. The purpose of this article was to calculate the X-ray spectrum in a mammography system with Monte Carlo codes, including MCNPX and MCNP5. Materials and Methods The device, simulated using the MCNP code, was Planmed Nuance digital mammography device (Planmed Oy, Finland), equipped with an amorphous selenium detector. Different anode/filter materials, such as molybdenum-rhodium (Mo-Rh), molybdenum-molybdenum (Mo-Mo), tungsten-tin (W-Sn), tungsten-silver (W-Ag), tungsten-palladium (W-Pd), tungsten-aluminum (W-Al), tungsten-molybdenum (W-Mo), molybdenum-aluminum (Mo-Al), tungsten-rhodium (W-Rh), rhodium-aluminum (Rh-Al), and rhodiumrhodium (Rh-Rh), were simulated in this study. The voltage range of the X-ray tube was between 24 and 34 kV with a 2 kV interval. Results The charts of changing photon flux versus energy were plotted for different types of anode-filter combinations. The comparison with the findings reported by others indicated acceptable consistency. Also, the X-ray spectra, obtained from MCNP5 and MCNPX codes for W-Ag and W-Rh combinations, were compared. We compared the present results with the reported data of MCNP4C and IPEM report No. 78 for Mo-Mo, Mo-Rh, and W-Al combinations. Conclusion The MCNPX calculation outcomes showed acceptable results in a low-energy X-ray beam range (10-35 keV). The obtained simulated spectra for different anode/filter combinations were in good conformity with the finding of previous research. [ABSTRACT FROM AUTHOR]

Purpose: A computational toolkit (SPEKTR 3.0) has been developed to calculate x-ray spectra based on the tungsten anode spectral model using interpolating cubic splines (TASMICS) algorithm, updating previous work based on the tungsten anode spectral model using interpolating polynomials (TASMIP) spectral model. The toolkit includes a matlab (The Mathworks, Natick, MA) function library and improved user interface (UI) along with an optimization algorithm to match calculated beam quality with measurements. Methods: The spektr code generates x-ray SPECTRA (photons/mm²/mAs at 100 cm from the source) using TASMICS as default (with TASMIP as an option) in 1 keV energy bins over beam energies 20-150 kV, extensible to 640 kV using the TASMICS spectra. An optimization tool was implemented to compute the added filtration (Al and W) that provides a best match between calculated and measured x-ray tube output (mGy/mAs or mR/mAs) for individual x-ray tubes that may differ from that assumed in TASMICS or TASMIP and to account for factors such as anode angle. Results: The median percent difference in photon counts for a TASMICS and TASMIP spectrum was 4.15% for tube potentials in the range 30-140 kV with the largest percentage difference arising in the low and high energy bins due to measurement errors in the empirically based TASMIP model and inaccurate polynomial fitting. The optimization tool reported a close agreement between measured and calculated spectra with a Pearson coefficient of 0.98. Conclusions: The computational toolkit, SPEKTR, has been updated to version 3.0, validated against measurements and existing models, and made available as open source code. Video tutorials for the spektr function library, UI, and optimization tool are available. [ABSTRACT FROM AUTHOR]

We present mathematical models and methods of the computational experiment using a three-dimensional RMHD model simulating the implosion of Z-pinches formed by an imploding cylindrical array of thin tungsten wires. The calculations take into account the discrete structure of the array and the extended plasma formation at the evaporation of the wire material and they yield the estimated values of the output power and X-ray spectrum. The data are presented on the spatio-temporal distribution in the parameters of the Z-pinch plasma, including the velocity, electron and ion temperatures, ionization degree, and the power output integrated over space. We have also calculated the characteristics of the Z- pinch X-ray spectrum depending on the photon energy at different times after the discharge current starts. It has been found that the trailing mass of tungsten on the periphery affects the emission intensity of the central part of the pinch in the radial direction, which can be explained by the emission absorption in the peripheral plasma layers of the trailing tungsten mass. A detailed model has been constructed of the central pinch formed by the electric current implosion of the material of multiwire tungsten arrays. This model enables one to calculate the intensity of the soft X-ray emission with a temporal, spatial, angular, and spectral resolution for specific experiments on the Angara-5-1 experimental complex intended to study the implosion of cylindrical multiwire arrays, for which there is sufficient information about the time profile of the absolute emission intensity in the low-energy range of the X-ray emission. The obtained numerical results can be directly compared with the experimental values. The RMHD model simulating the implosion of Z-pinches has been verified by comparing its results with the experimental implosion indicators. [ABSTRACT FROM AUTHOR]

This paper deals with X-ray spectrum measurement as a method for the measurement of radio frequent cavity voltage and the theory of X-ray spectrum calculation. Experimental results at 72 MHz for three different values of the radio frequent power of ACCEL K250 super conducting cyclotron are being presented.

Design and production of a simple and low cost X-ray imaging system that can be used for light industrial applications was targeted in the Nuclear Physics Laboratory of Istanbul Technical University. In this study, production, transmission and detection of X-rays were simulated for the proposed imaging device. OX/70-P dental tube was used and X-ray spectra simulated by Geant4 were validated by comparison with X-ray spectra measured between 20 and 35 keV. Relative detection efficiency of the detector was also determined to confirm the physics processes used in the simulations. Various time optimization tools were performed to reduce the simulation time. [ABSTRACT FROM AUTHOR]

The most accurate description of the radiation field in x-ray spectrometry requires the modeling of coupled photon–electron transport. Compton scattering and the photoelectric effect actually produce electrons as secondary particles which contribute to the photon field through conversion mechanisms like bremsstrahlung (which produces a continuous photon energy spectrum) and inner-shell impact ionization (ISII) (which gives characteristic lines). The solution of the coupled problem is time consuming because the electrons interact continuously and therefore, the number of electron collisions to be considered is always very high. This complex problem is frequently simplified by neglecting the contributions of the secondary electrons. Recent works ( Fernández et al., 2013; Fernández et al., 2014 ) have shown the possibility to include a separately computed coupled photon–electron contribution like ISII in a photon calculation for improving such a crude approximation while preserving the speed of the pure photon transport model. By means of a similar approach and the Monte Carlo code PENELOPE (coupled photon–electron Monte Carlo), the bremsstrahlung contribution is characterized in this work. The angular distribution of the photons due to bremsstrahlung can be safely considered as isotropic, with the point of emission located at the same place of the photon collision. A new photon kernel describing the bremsstrahlung contribution is introduced: it can be included in photon transport codes (deterministic or Monte Carlo) with a minimal effort. A data library to describe the energy dependence of the bremsstrahlung emission has been generated for all elements Z =1–92 in the energy range 1–150 keV. The bremsstrahlung energy distribution for an arbitrary energy is obtained by interpolating in the database. A comparison between a PENELOPE direct simulation and the interpolated distribution using the data base shows an almost perfect agreement. The use of the data base increases the calculation speed by several magnitude orders. [ABSTRACT FROM AUTHOR]

The total and partial densities of states of all components of CdGaSe are calculated using the modified ab initio augmented plane wave (APW) method implemented in the WIEN2k software package. The results of the APW calculations indicate that in the CdGaSe compound, the Se p states are the main contributions to the valence band, and their contribution is maximum at the top of the valence band, meanwhile at the bottom of the conduction band the contributions of the Ga s* states dominate. According to the theoretical APW-calculations, the Cd d and Ga p electronic states also contribute sufficiently to the valence band (mostly at the bottom and at the top of the band respectively) in CdGaSe. The joint alignment of Cd Lβ, Ga Kβ and Se Kβ X-ray emission bands and of the X-ray photoelectron spectrum of the valence electrons obtained for the CdGaSe single crystal, in a common energy scale, shows good agreement of the obtained theoretical and experimental data referring to the characteristic properties of the electronic structure of the CdGaSe compound. [ABSTRACT FROM AUTHOR]

Primary X-ray spectra were measured in the range of 80–150 kV in order to validate a computer program based on a semiempirical model. The ratio between the characteristic and total air Kerma was considered to compare computed results and experimental data. Results show that the experimental spectra have higher first HVL and mean energy than the calculated ones. The ratios between the characteristic and total air Kerma for calculated spectra are in good agreement with experimental results for all filtrations used. [ABSTRACT FROM AUTHOR]