X-ray Count Research Articles

Revisiting multiwavelength data on the supersoft X-ray source CAL 83

ABSTRACT In this study, we revisit public data on the supersoft X-ray source CAL 83 in the Large Magellanic Cloud. A significant part of our analysis is focused on XMM–Newton X-ray observations, in which updated data reduction procedures and quality assessment were applied. We report on the capability of publicly available hot atmosphere models in describing the source’s soft X-ray spectrum. By gathering historical flux measurements in multiple wavelengths and comparing them with the fluxes derived from the X-ray analysis, we find that an ∼360 kK phenomenological blackbody model describes the spectral energy distribution of CAL 83 fairly well. We also retrieve data from the XMM–Newton ultraviolet (UV)/optical camera, which is co-aligned with the X-ray instruments and provides strictly simultaneous measurements. These observations demonstrate that the X-ray emission is definitely anti-correlated with emission at longer wavelengths on a time-scale of days to weeks. A closer look at simultaneous X-ray and UV count rates in single light curves reveals that the anti-correlated behaviour is actually present on time-scales as short as minutes, suggesting that the origin of variable emission in the system is not unique.

UV–Optical Disk Reverberation Lags despite a Faint X-Ray Corona in the Active Galactic Nucleus Mrk 335

We present the first results from a 100-day Swift, NICER, and ground-based X-ray–UV–optical reverberation mapping campaign of the Narrow-line Seyfert 1 Mrk 335, when it was in an unprecedented low X-ray flux state. Despite dramatic suppression of the X-ray variability, we still observe UV–optical lags as expected from disk reverberation. Moreover, the UV–optical lags are consistent with archival observations when the X-ray luminosity was >10 times higher. Interestingly, both low- and high-flux states reveal UV–optical lags that are 6–11 times longer than expected from a thin disk. These long lags are often interpreted as due to contamination from the broad line region; however the u-band excess lag (containing the Balmer jump from the diffuse continuum) is less prevalent than in other active galactic nuclei. The Swift campaign showed a low X-ray-to-optical correlation (similar to previous campaigns), but NICER and ground-based monitoring continued for another 2 weeks, during which the optical rose to the highest level of the campaign, followed ∼10 days later by a sharp rise in X-rays. While the low X-ray countrate and relatively large systematic uncertainties in the NICER background make this measurement challenging, if the optical does lead X-rays in this flare, this indicates a departure from the zeroth-order reprocessing picture. If the optical flare is due to an increase in mass accretion rate, this occurs on much shorter than the viscous timescale. Alternatively, the optical could be responding to an intrinsic rise in X-rays that is initially hidden from our line of sight.

Counting-loss correction method based on window pulse shaping

In order to obtain a precise X-ray counting rate, a window shaping algorithm is proposed and is applied. The proposed algorithm shapes original pulses into window pulses with sharp edge and stable width. In the experiment, the measured counting rate at 3.9uA tube current is used to estimate the incoming counting rate. The dead time and corrected counting rate are estimated by the paralyzable dead-time model. The experimental results show that the mean dead time of radiation events is 260ns and the relative mean deviation is 3.44% in the newly designed counting system. While the incoming counting rate is in the range of 100kcps to 2Mcps, the relative error of the corrected counting rate compared with the incoming counting rate is less than 1.78%. The proposed algorithm suppresses the dead time swing and improves the accuracy of the total counting rate of X-ray fluorescence spectrum.

Association of Iron Deficiency Anemia with Pneumonia in 6 Months to 5 Years Old Children

Background: Pneumonia is the leading cause of childhood death under five years old in developing countries. Anemia is the commonest ailment affecting health, socio-economic development and the overall betterment of mankind. This study was conducted to determine the association between iron deficiency anemia (IDA) and pneumonia in the age group 6 months to 5 years.
 Methods: A cross-sectional analytical study was conducted in the Department of Pediatrics, SSMC & Mitford Hospital. According to selection criteria, 64 patients with pneumonia were considered as cases and matched 64 patients with fever and cough and but having no pneumonia, participated as control. Chest X-ray and complete blood count with RBC indices, iron profile was done to see pneumonia and IDA. A comparison was done between two groups. p-value was significant when < 0.05.
 Results: The mean age was 18.65±16.43 months in the case group and 14.17±10.76 months in the control group. Male was found 65.6% in the case and 73.4% in the control group. Females were 34.4% in the case and 26.6% in the control group. No significant difference in age and sex between the two groups. Decreased level of Hb, RBC, MCV, MCHC & increase RDW and also decreased level of serum iron, ferritin, transferrin & increased TIBC in the case group; all of which were statistically significant when compares to the control group. IDA was 65.6% in the case group; 17.2% in the control group. IDA was significantly higher in the case group compared to the control group.
 Conclusion: Sixty-six percent of children of 6 months to 5 years of both sexes with pneumonia associated with IDA. So, Iron deficiency anemic child more risk of developing pneumonia.
 EMCJ. July 2022; 7(2): 10-15

Degradation of signal-to-noise ratio in counting detectors due to pile-up effects

This work proposes a methodology to quantify how the non-linearity of counting detectors due to pulse pile-up effects impacts detrimentally the signal-to-noise ratio of measurements and the resulting DQE. The method is presented from a conceptual point of view, justified and validated by both analytical and Monte Carlo methods applied to the ideal theoretical pile-up models usually discussed in the literature. Although the motivation of this work is the application to photon counting X-ray detectors, the study may be relevant for other type of particle or radiation detection systems operating at high count rate regimes, when pile-up is not negligible. The high count rates can be managed in actual experiments by implementing pile-up compensation methods in the detector readout chain, by applying correction algorithms to the measured data or by a combination of both. What has been less discussed in literature is the impact of those pile-up compensation techniques on the final statistical properties of the resulting data, and the proposed method can be potentially used for that purpose. The application of the method to more realistic systems is illustrated with an example of a simulated 2D X-ray photon counting detector that includes all the primary physical effects and the full readout chain.

Barometers Behaving Badly I: Assessing the Influence of Analytical and Experimental Uncertainty on Clinopyroxene Thermobarometry Calculations at Crustal Conditions

Abstract The composition of clinopyroxene and clinopyroxene-liquid (Cpx-Liq) pairs are frequently used to calculate crystallization/equilibration pressures in igneous systems. While canonical uncertainties are often assigned to calculated pressures based on fits to calibration or test datasets, the sources of these uncertainties (and thus ways to reduce them) have not been rigorously assessed. We show that considerable uncertainties in calculated pressures arise from analytical error associated with Electron Probe Microanalyser (EPMA) measurements of Cpx. Specifically, low X-ray counts during analysis of elements with concentrations <1 wt% resulting from insufficient count times and/or low beam currents yield highly imprecise measurements (1σ errors of 10–40% for Na2O). Low analytical precision propagates into the calculation of pressure-sensitive mineral components such as jadeite. Using Monte Carlo approaches, we demonstrate that elemental variation resulting from analytical precision alone generates pressures spanning ~4 kbar (~15 km) for a single Cpx and ~6 kbar for a single Cpx-Liq pair using popular barometry expressions. In addition, analytical uncertainties in mineral compositions produce highly correlated arrays between pressure and temperature that have been previously attributed to transcrustal magma storage. Before invoking such geological interpretations, a more mundane origin from analytical imprecision must be ruled out. Most importantly, low analytical precision does not just affect the application of barometers to natural systems; it has also affected characterization of Cpx in experimental products used to calibrate and test barometers. The impact of poor precision on each individual measurement is often magnified by the small number of measurements made within experimental charges, meaning that low analytical precision and true variability in mineral compositions have not been sufficiently mediated by averaging multiple EPMA analyses. We compile the number of Cpx measurements performed in N = 307 experiments used to calibrate existing barometers, and N = 490 new experiments, finding ~45% of experiment charges were characterized by ≤5 individual Cpx analyses. Insufficient characterization of the true composition of experimental phases likely accounts for the fact that all Cpx-based barometers exhibit large errors (± 3 kbar) when tested using global experimental datasets. We suggest specific changes to analytical and experimental protocols, such as increased count times and/or higher beam currents when measuring low concentration elements in relatively beam resistant Cpx in experiments and natural samples. We also advocate for increasing the number of analyses per experimental charge, resolving interlaboratory analytical offsets and improving data reporting. Implementing these changes is essential to produce a more robust dataset to calibrate and test the next generation of more precise and accurate Cpx-based barometers. In turn, this will enable more rigorous investigation of magma storage geometries in a variety of tectonic settings (e.g. distinguishing true transcrustal storage vs. storage in discrete reservoirs).

Pediatric Covid-19 Patients Laboratory Characteristics in Dr.Ramelan Central Navy Hospital: A-Year Epidemiology Study

Covid-19 in children has several different characteristics with the adults, from clinical manifestation to laboratory result. There is also challenges in Covid-19 diagnosis in children with their inability to describe their condition clearly. Laboratory examination used to confirm the diagnosis, but the accuracy still in doubt. We aims to describe the laboratory examination result of pediatric Covid-19 patients. We analyze the medical records of 69 children with suspect Covid-19 who hospitalized in isolation room in a year period, from May 2020 to April 2021. All of the suspect patient were examined by PCR test, rapid antibody test, chest x-ray, and complete blood count.
 40 patients were Covid-19 positively-confirmed by the PCR test. Chest x-ray gave better sensitivity and specificity for early screening than rapid antibody test. The complete blood count gave normal results in general, only slight relative lymphocytosis occurred. The neutrophilia and lymphopenia pattern in adults with Covid-19 are different with the children’s result. The increase of NLR, who commonly used as an early screening test in adult Covid-19, cannot be used in children. The lower inflammatory response and physiologically higher lymphocyte cell count in younger age explain these results. In conclusion, the laboratory test should be performed for pediatric Covid-19 cases, but not for confirm the diagnosis.

X-ray emission from cosmic web filaments in SRG/eROSITA data

Using the publicly available eROSITA Final Equatorial Depth Survey (eFEDS) data, we detected the stacked X-ray emissions at the position of 463 filaments at a significance of 3.8σbased on the combination of all energy bands. In parallel, we found that the probability of the measurement under the null hypothesis is ∼0.0017. The filaments were identified with galaxies in the Sloan Digital Sky Survey survey, ranging from 30 Mpc to 100 Mpc in length at 0.2 < z < 0.6. The stacking of the filaments was performed with the eFEDS X-ray count-rate maps in the energy range between 0.4 and 2.3 keV after masking the resolved galaxy groups and clusters and the identified X-ray point sources from the ROSAT,Chandra,XMM-Newton, and eROSITA observations. In addition, diffuse X-ray foreground and background emissions or any residual contribution were removed by subtracting the signal in the region between 10 and 20 Mpc from the filament spines. For the stacked signal, we performed an X-ray spectral analysis, which indicated that the signal is associated with a thermal emission. According to a model with the astrophysical plasma emission code for the plasma emission and with aβ-model gas distribution withβ = 2/3, the detected X-ray signal can be interpreted as emission from hot gas in the filaments with an average gas temperature of 1.0−0.2+0.3keV and a gas overdensity of 21 ± 5 at the center of the filaments.

Etiology of Congestive Heart Failure in Children

Objective: To determine the frequency of common causes of congestive heart failure among children in a tertiary care hospital. Study Design: Cross-sectional study Place and Duration of Study: Department of Paediatrics Medicine, Services Hospital, Lahore from 1st January 2018 to 30th June 2018. Methodology: Ninety children were enrolled. Demographic information like name, age, gender, weight of child was noted. Complete blood count, echocardiography and chest X-ray were done. Children underwent assessment for presence of causes of congestive heart failure. Results: Fifty six (62.22%) were between 2-30 months of age whereas 34 (37.78%) were between 31-60 months of age with mean age 29.4±12.47 months. There were 40 (44.44%) males and 50 (55.56%) females. The causes of CCF were acute myocarditis in 39 (43.33%), congenital heart disease in 31 (34.44%) and severe anemia in 20 (22.33%). Conclusion: Acute myocarditis is one of the common causes of congestive heart failure in children aftersevere anemiaand congenital heart disease. Keywords: Congestive heart failure, Common causes, Acute myocarditis, Congenital heart disease, Severe anemia

Clinical and laboratory comparison between End-Stage Kidney Disease patients with and without COVID-19: a cross-sectional study in a top referred hospital of West Nusa Tenggara

Background: The initial presentation of hospitalized End-Stage Kidney Disease (ESKD) patients with and without coronavirus disease 2019 (COVID-19) is similar and can overlap. We aimed to compare clinical dan laboratory characteristics of the COVID-19 positive and negative patients to help clinicians screen and differentiate hospitalized ESKD patients. Methods: We reviewed data from the medical record of ESKD patients hospitalized between May 1, 2020, and April 30, 2021. The study comprised all suspected COVID-19 patients. The COVID-19 positive was based on results from RT-PCR for SARS-CoV-2. The bivariate analysis was used to compare the positive and negative groups. The association of all characteristics and diagnosis of COVID-19 were then evaluated by multivariable analysis. Results: There was twenty-nine percent of confirmed COVID-19 in 176 ESKD patients. The proportion of dyspnea, pulmonary edema, pleural effusion, and cardiomegaly were lower in the COVID-19 positive group. Diastolic blood pressure, pulse rate, white blood cell differential counts, and potassium were lower in the COVID-19 positive group. Using a multivariate analysis, eosinophil count <0.04 x103µl (P<0.001, OR 3.50, 95%CI:0.123-0.665), monocyte count <0.69 x103µl (P=0.004, OR 2.54, 95%CI:0.166-0.931), and neutrophil-to-lymphocyte ratio (NLR) <3.13 (P=0.044, OR 3.18, 95%CI:0.102-0.968) were associated with the presence of COVID-19. Conclusions: Leukocyte differential count and chest x-ray should be evaluated as an initial screening of COVID-19 in hospitalized ESKD. Low levels of monocyte and eosinophil count and mild elevation of NLR were associated with COVID-19 in ESKD patients.

A Library of Synthetic X-Ray Spectra for Fitting Tidal Disruption Events

We present a tabulated version of our slim-disk model for fitting tidal disruption events (TDEs). We create a synthetic X-ray spectral library by ray-tracing stationary general relativistic slim disks and including gravitational redshift, Doppler, and lensing effects self-consistently. We introduce the library to reduce computational expense and increase access for fitting future events. Fitting requires interpolation between the library spectra; the interpolation error in the synthetic flux is generally <10% (it can rise to 40% when the disk is nearly edge-on). We fit the X-ray spectra of the TDEs ASASSN-14li and ASASSN-15oi, successfully reproducing our earlier constraints on black hole mass M • and spin a • from full on-the-fly ray-tracing. We use the library to fit mock observational data to explore the degeneracies among parameters, finding that (1) spectra from a hotter thermal disk and edge-on inclination angle offer tighter constraints on M • and a •; (2) the constraining power of spectra on M • and a • increases as a power law with the number of X-ray counts, and the index of the power law is higher for hotter thermal disk spectra; (3) multiepoch X-ray spectra partially break the degeneracy between M • and a •; (4) the time-dependent level of X-ray absorption can be constrained from spectral fitting. The tabulated model and slim-disk model are available at https://doi.org/10.25739/hfhz-xn60.

Synchrotron X-ray Radiation (SXR) in Medical Imaging: Current Status and Future Prospects

Synchrotron X-ray radiation (SXR) has been widely studied to explore the structure of matter. Recently, there has been an intense focus on the medical application of SXR in imaging. This review is intended to explore the latest applications of SXR in medical imaging and to shed light on the advantages and drawbacks of this modality. The article highlights the latest developments in other fields that can greatly enhance the capability and applicability of SXR. The potentials of using machine and deep learning (DL)-based methods to generate synthetic images to use in regular clinics along with the use of photon counting X-ray detectors for spectral medical imaging with SXR are also discussed.

Spatial Power Spectral Analysis of the Suzaku X-Ray Background

Power spectra of spatial fluctuations of X-ray emission may impose constraints on the origins of the emission independent of that from the energy spectra. We generated spatial power spectrum densities (PSDs) of blank X-ray skies observed with the Suzaku X-ray observatory utilizing the modified Δ-variance method. Using the total measured count rate as the diagnostic tool, we found that a model consisting of the sum of two components, one for the unresolved faint point sources and one for the uniform flat-field emission, can represent well the observed PSD in three different energy bands (0.2–0.5, 0.5–2, and 2–10 keV); only an upper limit is obtained for the latter component in 2–10 keV. X-ray counting rates corresponding to the best-fit PSD model functions and diffuse emission fractions were estimated, and we confirmed that the sum of the counting rates of two model components is consistent with those actually observed with the detector for all energy bands. The ratio of the flat-field counting rate to the total in 0.5–2 keV, however, is significantly larger than the diffuse emission fraction estimated from the model fits of energy spectra. We discussed that this discrepancy can be reconciled by systematic effects in the PSD and energy spectrum analyses. The present study demonstrates that the spatial power spectrum analysis is powerful in constraining the origins of the X-ray emission.

Pyroelectric material property considerations for x-ray generation

The method of generating x-rays using the pyroelectric effect has garnered interest for applications that desire portability and low power consumption, particularly for real-time in-field and on-line analyses. However, the x-ray intensity produced by this type of x-ray generator is low and inconsistent compared to conventional x-ray tubes. The properties of several pyroelectric materials, including LiTaO3, LiNbO3, and PMN-xPT, were studied and subsequently tested on an in-house developed x-ray generator to explore their suitability for the application. The production of electrons to subsequently generate x-ray relies on the process of ferroelectric electron emission and field ionization to be dominant over charge compensation via the DC conductivity of the pyroelectric material. Given that the time of temperature change occurs faster than the material's charge relaxation time, it was found that the ratio of the pyroelectric coefficient to relative permittivity determined the performance of the x-ray generator. Thus, the x-ray count rates and end-point energies produced by LiTaO3 showed that it continues to be a strong candidate for such x-ray generation applications.

IDeF-X HDBD: Low-Noise ASIC for Imaging Spectroscopy With Semiconductor Detectors in Space Science Applications

We present the IDeF-X HDBD integrated circuit, our latest 32-channel application specified integrated circuit devoted to semiconductor photon counting X-ray detectors, designed to read charges ranging from −40 to 40 fC. The chip reaches an equivalent noise charge (ENC) floor of 17 electrons rms and is optimized for low input capacitance (< 10 pF). Each channel is based on an optimized charge sensitive amplifier (CSA) followed by a CR-RC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> filter and a peak detector with a power consumption of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$850 ~\mu \text{W}$ </tex-math></inline-formula> /channel. Gain and shaping times are tunable. This circuit has been designed with radiation mitigation techniques to meet space application requirements. This ASIC can read either cadmium telluride or silicon detectors for imaging-spectroscopy applications. An energy resolution of 230-eV FHWM at 6 keV and a low-level threshold of 1.2 keV were demonstrated with a single pixel silicon drift detector connected to one channel.

X-Ray Chronicles of Alpha Centauri: The Swooning of α Cen B

Abstract The central AB binary of Alpha Centauri has been visited regularly by Chandra X-ray Observatory since late 2005. Up to mid-2020, the B component, an early K dwarf, had traced out a relatively smooth 8 yr coronal (T ∼ 2 MK) activity cycle. Recently, however, B’s X-ray count rate suddenly dipped, from cycle maximum levels to near minimum in just 16 months. Previous cycle decays were 3–4 yr. The significance of the swoon remains to be seen.

Analysis and evaluation of liquid metal anode target material of transmission X-ray tube

In recent years, due to the fluidity and thermal conductivity of the liquid metal, the use of liquid metal as an anode target is one of the ways to improve the brightness of X-ray tubes. In this paper, the optimal thickness and conversion efficiency of three kinds of target materials under different energies were discussed by the Monte Carlo method. The optimal thickness of the gallium target is 6.2 μm when the incident electron beam energy is 50 keV and the optimal thickness of the indium target and the tin target was 4 μm. The X-ray conversion efficiency of the gallium target was 44.28% higher than that of the silver target as well as the ratio of X-ray count with the K lines to total count was 53.38%. The gallium target is suitable to be the material of a liquid metal anode target of transmission X-ray tube within the concerned energy range.

Mo/4H-SiC Schottky diodes for room temperature X-ray and [formula omitted]-ray spectroscopy

Mo/4H-SiC Schottky diodes were investigated as detectors for their suitability in photon counting X-ray and γ-ray spectroscopy. The Schottky diodes, with a 35μm thick n− epitaxial layer, were treated with a phosphorus pentoxide surface passivation, which had been previously shown to improve the homogeneity of the metal–semiconductor interface and suppress leakage current. One device was coupled to a low-noise charge sensitive preamplifier and standard onwards readout electronics; the resultant spectrometer was used to accumulated X-ray and γ-ray spectra. The spectrometer had an energy resolution of 1.67 keV ± 0.08 keV (97 e− rms ± 5 e− rms) at 5.9 keV and 1.6 keV ± 0.1 keV (93 e− rms ± 6 e− rms) at 59.54 keV. Despite the moderate energy resolution achieved, the results suggested that the leakage current of the Mo/4H-SiC Schottky diode detector was not the dominant source of noise limiting the energy resolution of the spectrometer at the optimum operating conditions at room temperature; lossy dielectrics in close proximity to the input of the preamplifier (including stray dielectrics) and the relatively large average electron–hole pair creation energy of 4H-SiC (an inherent property) were the main contributors to the achieved energy resolution in energy terms.

K-shell x-ray of Al produced by collisions of ions with near Bohr velocities

X-ray emissionproduced by highly charged ions with the energy range near the Bohr velocity involves complicated atomic process. However, duo to the limitation of experimental conditions, the relevant researches are nearly absent. It is unclear whether the existing theory is applicable in such an energy range. This needs further exploring. In the present work, K X-ray spectra of Al excited by H&lt;sup&gt;+&lt;/sup&gt;, He&lt;sup&gt;2+&lt;/sup&gt; and highly charged heavy ions I&lt;sup&gt;22+&lt;/sup&gt; and Xe&lt;sup&gt;20+&lt;/sup&gt; are investigated by using an Si drift X-ray detector in the energy range near the Bohr velocity. The X-ray production cross sections are extracted from the X-ray counts and compared with the theoretical simulations from PWBA, ECPSSR and modified BEA model. It is indicated that the cross section increases with the augment of projectile energy. With the same incident energy per nucleon, the cross section induced by highly charged heavy ions is a factor of about 10&lt;sup&gt;4&lt;/sup&gt; larger than that by light ions . With the impact of H&lt;sup&gt;+&lt;/sup&gt; and He&lt;sup&gt;2+&lt;/sup&gt; ions, the K-shell electrons are mainly knocked off through the direct Coulomb ionization, and the X-ray emission cross section can be well predicted by ECPSSR theory. For the bombardment of highly charged heavy ions I&lt;sup&gt;22+&lt;/sup&gt; and Xe&lt;sup&gt;20+&lt;/sup&gt;, except for the Coulomb ionization, the orbital electrons can also be excited by electron capture. The BEA simulation after being modified by both Coulomb repulsion and effective charge can well predict the x-ray production cross section.

K-shell X-ray of Al produced by collisions of ions with near Bohr velocities

X-ray emissionproduced by highly charged ions with the energy range near the Bohr velocity involves complicated atomic process. However, duo to the limitation of experimental conditions, the relevant researches are nearly absent. It is unclear whether the existing theory is applicable in such an energy range. This needs further exploring. In the present work, K X-ray spectra of Al excited by H&lt;sup&gt;+&lt;/sup&gt;, He&lt;sup&gt;2+&lt;/sup&gt; and highly charged heavy ions I&lt;sup&gt;22+&lt;/sup&gt; and Xe&lt;sup&gt;20+&lt;/sup&gt; are investigated by using an Si drift X-ray detector in the energy range near the Bohr velocity. The X-ray production cross sections are extracted from the X-ray counts and compared with the theoretical simulations from PWBA, ECPSSR and modified BEA model. It is indicated that the cross section increases with the augment of projectile energy. With the same incident energy per nucleon, the cross section induced by highly charged heavy ions is a factor of about 10&lt;sup&gt;4&lt;/sup&gt; larger than that by light ions . With the impact of H&lt;sup&gt;+&lt;/sup&gt; and He&lt;sup&gt;2+&lt;/sup&gt; ions, the K-shell electrons are mainly knocked off through the direct Coulomb ionization, and the X-ray emission cross section can be well predicted by ECPSSR theory. For the bombardment of highly charged heavy ions I&lt;sup&gt;22+&lt;/sup&gt; and Xe&lt;sup&gt;20+&lt;/sup&gt;, except for the Coulomb ionization, the orbital electrons can also be excited by electron capture. The BEA simulation after being modified by both Coulomb repulsion and effective charge can well predict the X-ray production cross section.