Vol.30,

We have proposed a pocket formulae for mass attenuation coefficient (μ/ρ), mass energy absorption coefficient (μ_en/ρ), and effective atomic number (Z_eff) in different tissues of human organs. We have also assigned a new chemical formula for all studied tissues based on their composition. We have introduced a new parameter called effective composition index (C_eff). Based on this we have introduced a new method to compute the effective atomic number. The evaluated photon interaction parameters are graphically represented. The evaluated average, maximum, minimum and standard deviations of effective atomic number are tabulated. The proposed formulae produces a mass attenuation coefficient, mass-energy absorption coefficient, and effective atomic number from their composition.

422

Today, millions of electrocommunication, electric, medical, and industrial devices use battery. Batteries with long life and high energy density seems to be essential in medical, military, oil and mining, aerospace areas as well as conditions in which access is difficult and in situations where replacement or recharging of battery is costly. In this regard, the use of radiation energy resulting from radioactive materials and its conversion to electric energy can be effective in making batteries. In the present study, various Mo-99 radioisotope values with a half-life of 65.98 h were used as a soluble radioactive source in two materials of water and aqua regia. Then, by comparing the results of the Monte Carlo simulations program MCNPX for these to solution, it was found that when the water is used instead of Aqua regia (for idealization), the values of the superficial current of electrons, the volumetric flux of electrons and the deposited energy in the volume containing the radioactive solution increased by 10.80, 4.10, and 13.80% respectively. Also, the short circuit current and energy conversion efficiency of this battery with a concentration of 0.01 Molar, Mo-99 dissolved in the aqua regia are 0.79 µA and 16.47%, respectively.

604

The method based on solvent parameters (mass, cycle of acidification, and autodeposition time), combined with response surface method (RSM) modelling and optimization, has been developed for maximizing ²¹⁰Po activity in tea samples, as observed by an alpha spectrometer. RSM based on 3-factor and 5-level composite center design (CCD) was used to obtain the optimal combination of solvent conditions. As solvent parameters for ²¹⁰Po activity, different masses (0.5, 0.75, 1, 1.5, and 2 g), different cycles of acidification (2, 3, 4, 5, and 6 times), and different autodeposition times (2, 3, 4, 5, and 6 h) were studied. The 3D response surface plot and the contour plot derived from the mathematical models were used to determine the optimal conditions. According to the obtained results, the experimental value of ²¹⁰Po activity was in good agreement (R² = 0.96) with the value predicted by the model. We found a favorable effect of mass on the ²¹⁰Po activity (p < 0.05).

323

In this study, the activity concentrations of ²²⁶Ra, ²³²Th, ²²²Rn, and ⁴⁰K, emanation fractions (P), equilibrium equivalent concentration (EEC), and mass exhalation rates (E_m) of radon released from building materials used in Malaysia were studied using gamma-ray spectrometer with HPGe detector. Radiological parameters (activity concentration index (ACI), indoor air absorbed dose rate (D_in), annual effective dose (AED_in) from external and internal (E_Rn), soft tissues (H_ST) and lung (H_L) and effective dose equivalent (H_eff)) were estimated to evaluate radiological hazards due to use of these building materials: sand, cement, gravel, bricks, tiles, fly ash, white cement, and ceramic raw materials. The measured P, EEC, and E_m vary from 10 to 30 %, 0.9 to 22 Bq m^-3, and 33 to 674 mBq h^-1 kg^-1, respectively. While the calculated ACI and AED_in vary from 0.1 ± 0.01 to 2.1 ± 0.1 and 0.1 ± 0.01 to 2.4 ± 0.6 mSv y^-1, respectively. On the other hand, the internal annual effective dose ranges from 0.1 to 1.4 mSv y^-1. The estimated radiological risk parameters were below the recommended maximum values and radiological hazards associated with building materials under investigation are therefore negligible.

329

This study reports the performances of efficiency calibrations for high-purity-germanium gamma-ray spectrometry using the source-, Laboratory-Sourceless-Object-Calibration -Software-(LabSOCS)- and ANGLE-based methods in an inter-comparison exercise. Although the results of LabSOCS and ANGLE for ²⁴¹Am emitting low-energy gamma rays were not very satisfactory, all of the three efficiency calibration methods passed acceptance criteria. The results confirmed the reliability of the calculation codes ANGLE and LabSOCS as alternative efficiency calibration methods in high-purity-germanium gamma spectrometry. This study is likely to promote the further application of the ANGLE and LabSOCS calculation codes in radioactivity measurements.

356

Spectral computed tomography (CT) based on photon counting detectors (PCDs) is a well-researched topic in the field of X-ray imaging. When PCD is applied in a spectral CT system, the PCD energy thresholds must be carefully selected, especially for K-edge imaging, which is an important spectral CT application. This paper presents a threshold selection method that yields better quality images in K-edge imaging. The main idea is to optimize the energy thresholds ray-by-ray according to the targeted component coefficients, followed by obtaining an overall optimal energy threshold by frequency voting. A low-dose pre-scan is used in practical implementations to estimate the line integrals of the component coefficients for the basis functions. The variance of the decomposed component coefficients is then minimized using the Cramer–Rao lower bound (CRLB) method with respect to the energy thresholds. The optimal energy thresholds are then used to take a full scan and gain better image reconstruction with less noise than would be given by a full scan using the nonoptimal energy thresholds. Simulations and practical experiments on imaging iodine (I) and gadolinium (Gd) solutions, which are commonly used as contrast agents in medical applications, were used to validate the method. The noise was significantly reduced with the same dose relative to the nonoptimal energy thresholds in both simulations and in practical experiments.

326

Distributed X-ray sources comprise a single vacuum chamber containing multiple X-ray sources that are triggered and emit X-rays at a specific time and location. This process facilitates an application for innovative system concepts in X-ray and computer tomography (CT). This paper proposes a novel electron beam focusing, shaping, and deflection electron gun for distributed X-ray sources. The electron gun uses a dispenser cathode as an electron emitter, a mesh grid to control emission current, and two electrostatic lenses for beam shaping, focusing, and deflection. Novel focusing and deflecting electrodes were designed to increase the number of focal spots in the distributed source. Two identical half-rectangle opening electrodes are controlled by adjusting the potential of the two electrodes to control the electron beam trajectory, and then multi-focal spots are obtained on the anode target. The electron gun can increase the spatial density of the distributed X-ray sources, thereby improving the image quality. The beam experimental results show that the focal spot sizes of the deflected (deflected amplitude, 10.5 mm) and non-deflected electron beams at full width at half maximum (FWHM) are 0.80 mm × 0.50 mm and 0.55 mm × 0.40 mm, respectively (anode voltage, 160 kV; beam current, 30 mA). The imaging experimental results demonstrate the excellent spatial resolution and time resolution of an imaging system built with the sources, which has an excellent imaging effect on a field-programmable gate array (FPGA) chip and a rotating metal disk.

383

The full-spectrum least-squares (FSLS) method is introduced to perform quantitative energy-dispersive X-ray fluorescence analysis for unknown solid samples. Based on the conventional least-squares principle, this spectrum-evaluation method is able to obtain the background-corrected and interference-free net peaks, which is significant for quantization analyses. A variety of analytical parameters and functions to describe the features of the fluorescence spectra of pure elements are used and established, such as the mass-absorption coefficient, the Gi factor, and fundamental fluorescence formulas. The FSLS iterative program was compiled in the C language. The content of each component should reach the convergence criterion at the end of the calculations. After a basic theory analysis and experimental preparation, 13 National Standard Soil samples were detected using a spectrometer to test the feasibility of using the algorithm. The results show that the calculated contents of Ti, Fe, Ni, Cu, and Zn have the same changing tendency as the corresponding standard content in the 13 reference samples. Accuracies of 0.35% and 14.03% are obtained, respectively, for Fe and Ti, whose standard concentrations are 8.82% and 0.578%, respectively. However, the calculated results of trace elements (only tens of ppm) deviate from the standard values. This may be because of measurement accuracy and mutual effects between the elements.

485

In pursuit of a fully coherent X-ray free-electron laser (FEL), highly reflective Bragg crystals are used and will be used as a highly selective spectral filter in hard X-ray self-seeding FELs and X-ray FEL oscillators (XFELO), respectively. However, currently, when simulating self-seeding and XFELO, the three-dimensional effect of Bragg diffraction is not fully considered. In this paper, we derive a comprehensive solution for the response function of the crystal in Bragg diffraction. A three-dimensional X-ray crystal Bragg diffraction code, named BRIGHT, is introduced, which can be combined with other FEL-related codes, e.g., GENESIS and OPC. Performance and feasibility are assessed using two numerical examples, namely, a self-seeding experiment for the Linac Coherent Light Source and XFELO options for Shanghai high repetition rate XFEL. The results indicate that BRIGHT provides a new and useful tool for three-dimensional modeling of FEL.

369

A new nondestructive method to estimate the volume fraction and homogeneity of tristructural isotropic (TRISO)-coated fuel particles in fuel compacts designed for high-temperature reactors has been developed using image analysis of conventional X-radiographs. The method is demonstrated on surrogate fuel compacts containing TRISO-coated particles with kernels made of zirconium dioxide. The methodology incorporates a correction for superimposed images of TRISO particles such that a single X-ray image obtained in any one random orientation is sufficient to characterize the fuel compact in terms of volume fraction and homogeneity. The method is based on the virtual segregation of images of each particle inside the compact with the aid of a calibration standard.

448

Depletion calculation is important for studying the transmutation efficiency of minor actinides and long-life fission products in accelerator-driven subcritical reactor system (ADS). Herein the Python language is used to develop a burnup code system called IMPC-Burnup by coupling FLUKA, OpenMC, and ORIGEN2. The program is preliminarily verified by OECD-NEA pin cell and IAEA-ADS benchmarking by comparison with experimental values and calculated results from other studies. Moreover, the physics design scheme of the CIADS sub-critical core is utilized to test the feasibility of IMPC-Burnup program in the burnup calculation of ADS system. Reference results are given by the COUPLE3.0 program. The results of IMPC-Burnup show good agreement with those of COUPLE3.0. In addition, since the upper limit of the neutron transport energy for OpenMC is 20 MeV, neutrons with energies greater than 20 MeV in the CIADS subcritical core cannot be transported; thus, an equivalent flux method has been proposed to consider neutrons above 20 MeV in the OpenMC transport calculation. The results are compared to those that do not include neutrons greater than 20 MeV. The conclusion is that the accuracy of the actinide nuclide mass in the burnup calculation is improved when the equivalent flux method is used. Therefore, the IMPC-Burnup code is suitable for burnup analysis of the ADS system.

436

In resonance with the Fukushima Daiichi Nuclear Power Plant accident lesson, novel fuel design to enhance safety regarding severe accident scenarios has become increasingly appreciated in the nuclear power industry. This research focuses on analysis of the neutronic properties of a silicon carbide (SiC) cladding fuel assembly, which provides a greater safety margin as a type of accident-tolerant fuel for pressurized water reactors. The general physical performance of SiC cladding is explored to ascertain its neutronic performance. The neutron spectrum, accumulation of ²³⁹Pu, physical characteristics, temperature reactivity coefficient, and power distribution are analyzed. Furthermore, the influences of a burnable poison rod and enrichment are explored. SiC cladding assemblies show a softer neutron spectrum and flatter power distribution then conventional Zr alloy cladding fuel assemblies. Lower-enrichment fuel is required when SiC cladding is adopted. However, the positive reactivity coefficient associated with the SiC material remains to be offset. The results reveal that SiC cladding assemblies show broad agreement with the neutronic performance of conventional Zr alloy cladding fuel. In the meantime, its unique physical characteristics can lead to improved safety and economy.

447

350

Molten salt pebble-bed reactor is one of the sixth-generation IV reactor types. To investigate the mechanical behavior of the fuel pebbles in the core, a visualization experiment facility of pebble bed (VEFPB) is designed. To obtain a uniform flow field of the core and analyze the influence of the flow field on the structure of the pebble bed, computational fluid dynamics software Fluent is used to simulate the flow field distribution of the core of VEFPB. The simulation results show that the disturbance at the bottom of the pebble bed is proportional to the flow velocity of the inlet pipe, and the flow velocity close to the inlet side is more significant than that in other parts; the design of the cylinder bottom plate with holes of different sizes can effectively reduce the flow velocity and the disturbance at the bottom of the pebble bed. In addition, according to the velocity contours of the core of VEFPB, it is observed that the flow field distribution of the core is considerably uniform except at the bottom of the pebble bed. This ensures the stability of the pebble bed and verifies the rationality of the design of VEFPB. This study provides the technical support and reference for the flow field analysis of the core of molten salt pebble-bed reactor.

511

A multichannel low-noise electronic prototype system was designed for a pixelated CdZnTe detector. This system is the result of preliminary work on a solar Hard X-ray imager, which is one of the three payloads for future solar observations satellite Advanced Space-based Solar Observatory (ASO-S). A new charge sensitive amplifier application specific integrated circuit, VATA450.3, with an on-chip analog-to-digital converter, is used to readout 8 x 8 anode pixel signals. Two CdZnTe detectors with a thickness of 2 mm and 5 mm were tested. The 2 mm-thick detector achieved energy resolution better than 5% (full width at half maximum, FWHM) at 59.5 keV, and the 5 mm-thick detector had better resolution than 1.2% (FWHM) at 662 keV. The design and test results of the prototype system are discussed in this paper.

631

Existing standards show a clear discrepancy in the specification of the maximum proton energy for qualified ground-based evaluation of single event effects, which can range from 180 MeV to 500 MeV. This work finds that the threshold linear energy transfer (LET) of a tested device is a critical parameter for determining the maximum proton energy. The inner mechanisms are further revealed. High-energy deposition events (>10 MeV) in sensitive volumes are attributed to the interaction between protons and the tungsten vias in the metallization layers.

422

The yield ratios of neutron/proton (R(n/p)) and ³H/³He (R(t/³He)) with reduced rapidity from 0 to 0.5 are investigated for 50 MeV/u ^{42,44,46,48,50,52,54,56}Ca + ⁴⁰Ca. This was conducted at whole reduced impact parameters using the isospin-dependent quantum molecular dynamics (IQMD) model in which the initial neutron and proton densities are sampled within the Skyrme-—Hartree–Fock model, using which the neutron skin thickness (ΔR_np) is determined for different neutron-rich Ca isotopes. The results show that both R(n/p) and R(t/³He) have strong linear correlations with ΔR_np of different Ca isotopic projectiles from five different centralities. It is suggested that R(n/p) and R(t/³He), from the same centrality, could be treated as possible experimental observables to extract the neutron skin or halo thickness for neutron-rich isotopic nuclei, including the nuclei near the neutron drip line.

490