Vol.29,

One of the most important safety features of nuclear facilities is the shielding material used to protect the operating personnel from radiation exposure. The most common materials used in radiation shielding are concretes. In this study, a Monte Carlo N-Particle eXtended (MCNPX) code is used to calculate the gamma-ray attenuation coefficients and dose rates for a new concrete material composed of MnFe₂O₄ nanoparticles, which is then compared with the theoretical and experimental results obtained for a SiO₂ nanoparticle concrete material. According to the results, the average relative differences between the simulations and the theoretical and experimental results for the linear attenuation coefficient (μ) in the SiO₂ nanoparticle materials are 6.4% and 5.5%, respectively. By increasing the SiO₂ content up to 1.5% and the temperature of MnFe₂O₄ up to 673 K, μ is increased for all energies. In addition, the photon dose rate decreases up to 9.2% and 3.7% for MnFe₂O₄ and SiO₂ for gamma-ray energies of 0.511 and 1.274 MeV, respectively. Therefore, it was concluded that the addition of SiO₂ and MnFe₂O₄ nanoparticles to concrete improves its nuclear properties and could lead to it being more useful in radiation shielding.

475

To calculate the radioactivity of product nuclides generated in pulse irradiation, it is generally assumed that the irradiation is approximately continues in the entire irradiation period (t_i) and the flux of incoming irradiation particle can be obtained by averaging their intensity in each pulse period (T). However, this approximation fails to acknowledge the fact that the product nuclides are not created in each pulse period (T) evenly: they are only produced in a very short pulse width (t_p) and then decay in a relative long rest time (t_r = T - t_p). Given by the enormous number of pulses, the sum of these decays may not be negligible. To make the activity calculation in accordance with the real situation in pulse irradiation, we scrutinize the details of irradiation and decay processes in each pulse, applies the geometric series to obtain the activity superimposition of millions of pulses, and derives a novel activity equation particularly suitable for pulse irradiation. The experimental results, numerical simulations, and activity measurements from photon activation driven by a pulsed electron LINAC have confirmed the validity of this new equation. The comparison between the new and traditional equations indicates that their discrepancy could be significant under certain conditions. The limitations of the new activity equation for pulse irradiation are discussed as well.

386

The ozonolysis of cyclohexene is an important model system for understanding the more complex reaction of O₃ with monoterpenes; however, many previous studies have come to qualitatively different conclusions about the composition of the secondary organic aerosol (SOA) formed in this system. In the present study, the composition of the SOA produced by cyclohexene ozonolysis in the absence of seed aerosols has been investigated on-line and off-line using synchrotron-based thermal desorption/tunable vacuum-ultraviolet photoionization time-of-flight aerosol mass spectrometry (TD-VUV-TOF-PIAMS) in conjunction with a custom-built smog chamber. On the basis of the molecular ions observed by mass spectrometry at 11.5 eV, it was found that dicarboxylic acids, dialdehydes, and cyclic anhydrides are the predominant low-molecular-weight components in the particle phase. The results also indicated that TD-VUV-TOF-PIAMS coupled with filter sampling is a potentially useful tool for the investigation of SOA composition both in the field and in the laboratory.

523

Harmonic RF cavities are commonly used in storage rings to lengthen the bunches and thus suppress the beam’s instabilities and increase its Touschek lifetime. The voltage and phase of the electromagnetic fields in the harmonic cavity are of great importance for stretching the bunch. In the Hefei Light Source storage ring, a passive fourth-harmonic cavity is installed, and the cavity is monitored and controlled by an analog control module provided by its manufacturer. To vary and maintain the voltage of the harmonic cavity in a more effective way, a digital proportional, integral, and derivative feedback system based on the Experimental Physics and Industrial Control System is developed on top of the analog control module. This paper reports the details of the development of this voltage control system. Some test and operational results are also presented.

536

A new and innovative detector system based on a silicon strip detector dedicated to the study of the reaction induced by lighter radioactive beams is described herein. The detector system consists of five sets of three types of telescopes, which are successfully used to measure the angular distributions of both elastic scattering and breakup simultaneously, on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at Heavy Ion Research Facility in Lanzhou (HIRFL). This silicon detector array is used to measure the elastic scattering angular distributions of ¹¹Be on a ²⁰⁸Pb target at E_lab=140 and 209 MeV. A comparison of the Monte Carlo simulations with the experimental results shows a reasonable consistency.

563

The CPPF Concentration Pre-Processing and Fan-out (CPPF) system is one of the electronic subsystems of the upgraded Compact Muon Solenoid (CMS) Level-1 trigger system. It includes, in hardware, eight specially designed CPPF cards, one CMS card called AMC13, one commercial Micro-TCA Carrier HUB (MCH) card, and a Micro-TCA shelf. Powerful online software is needed for the system, including providing reliable configuration and monitoring for the hardware, and a graphical interface for executing all actions and publishing monitoring messages. Further, to control and monitor the large amount of homogeneous hardware, the SoftWare Automating conTrol Hardware (SWATCH) concept was proposed and developed. The SWATCH provides a generic structure and is flexible for customization. The structure includes a hardware access library (HAL) based on the IPbus protocol, which assumes a virtual 32-bit address/32-bit data bus and builds a simple hardware access layer. Furthermore, the structure provides a graphical user interface, which is based on modern web technology, and is accessible by web page. The CPPF controlling and monitoring online software was also customized from a common SWATCH cell, and provides a finite state machine (FSM) for configuring the entire CPPF hardware, and five monitoring objects for periodically collecting monitoring data from five main functional modules in the CPPF hardware. This paper introduces the details of the CPPF SWATCH cell development.

358

The effects of mass asymmetry on the production of superheavy nuclei (SHN), within the dinuclear system (DNS) model, are investigated in this study. It is observed that the fusion probability decreases with decreasing mass asymmetry. A total of 192 possible combinations of projectiles from O to Ti and targets with half-lives longer than 30 days for producing SHN ²⁶⁴Db, ²⁶⁵Db, ²⁶⁷Sg, ²⁶⁸Bh, ²⁶⁸Sg, ²⁶⁹Bh, ²⁷¹Hs, ²⁷¹Mt, ²⁷²Hs, ²⁷²Mt, ²⁷³Mt, ²⁷⁴Ds, ²⁷⁵Ds, ²⁷⁵Rg, ²⁷⁶Ds, ²⁷⁶Rg, ²⁷⁷Rg, ²⁷⁸Cn, ²⁷⁹Cn, and ²⁸⁰Cn are examined. Further, the optimal combinations and incident energies for synthesizing these nuclei are predicted. Most of the cross sections for production of SHN are larger than 10 pb; therefore, the process can be carried out with the available experimental equipment.

629

The prediction of nuclear cross-section data is crucial, especially in the absence of experimental data or in the difficulty of this experimental data. Nickel (Ni) is an important material in fusion and fission reactor technologies, the production of radionuclides in nuclear medicine, and many other fields. In this study, the excitation functions for ^60,62Ni(α,n), ^60,61Ni(α,2n), ^58,64Ni(α,p), and ^natNi(α,x) reactions have been investigated by using pre-equilibrium reaction models. The calculations of the excitation functions for the reactions are used with the geometry dependent hybrid model in ALICE/ASH code and the two-component exciton model in TALYS 1.8 code. The obtained results are compared to each other and the experimental data is taken from the EXFOR database.

431

Colloidal gold nanoparticles (AuNPs) have attracted more and more attention in areas of materials science, biotechnology, and organic chemistry due to their unique functions as molecular markers and their use in diagnostic imaging and catalysis. The AuNP synthesis approaches have been well developed, however, the solvent effects have not been systematically studied yet. Here we analyzed and compared solvent effects on AuNP formation using UV irradiation of Au(III) without adding any other ligands. By monitoring the surface plasmon resonance (SPR) absorption of Au(III)-containing solutions, results showed that both ketone and alcohol solvents can induce Au(III) to form gold nanospheres, on the other hand, solvents like ACN and THF can induce Au(III) to form nanostructures with longer dimensions. The possible mechanism was discussed, which could facilitate efficient photochemical synthesis of AuNPs and might apply to other metal NP synthesis.

543

Considering the volatility of the propagation path for charmonium passing across the nuclear target in J/ψ formation from p-A collisions, the charmonium energy loss is investigated using Salgado-Wiedemann quenching weights. A successful description regarding J/ψ suppression of R_W(Fe)/Be(x_F) from the E866 experiment for 0.2 < x_F < 0.65 gives the transport coefficient q^=0.29±0.07 GeV²/fm for the colored cc¯ energy loss. The calculated result indicates that radiative energy loss of a parton should be independent of its mass at high energy. The calculations are further compared to LHC and RHIC measurements.

511

In order to study the influence of the shell effects on the formation and fission of superheavy elements we applied multidimensional Langevin equations. The Evaporation residue cross sections have been calculated for 3n, 4n, and 5n evaporation channels using three (K=0) and four (K ≠ 0) dimensional Langevin equations. Calculations were done for ⁴⁸Ca+²³⁸U and ⁴⁸Ca +²⁴⁴Pu hot fusion reactions with 3n, 4n evaporation channels and ⁷⁰Zn +²⁰⁸Pb, and ⁵⁴Cr +²⁰⁹Bi cold fusion reactions with 1n and 2n evaporation channels. The calculations were performed for 4n and 5n evaporation channels of the ²⁶Mg+²³⁸U reaction, as well. Our results show that with increasing dimension of Langevin equations the residue cross section increases whereas the fission cross section decreases. The obtained results with four dimensional Langevin and considering shell effects are in better agreement with experimental data in comparison with three and four dimensional Langevin equations without shell effects.

385

In random-interaction ensembles, the electric quadrupole moments (Q) and magnetic moments (μ) of the I^π=11/2^- isomers of the Cd isotopes predominantly exhibit a linear correlation with the neutron numbers, corresponding to the recently emphasized linear Q and μ systematics in realistic nuclear systems. Although the seniority scheme enhances such predominance (more essentially for μ), the configuration mixing due to quadrupole-like and δ-force-like proton-neutron (pn) interactions is responsible for the linear Q and μ systematics, respectively, in realistic nuclear system, as well as random-interaction ensembles.

475

The transverse momentum distributions of the identified particles produced in small collision systems at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) have been analyzed by four models. The first two models utilize the blast-wave model with different statistics. The last two models employ certain linear correspondences based on different distributions. The four models describe the experimental data measured by the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX), Solenoidal Tracker at RHIC (STAR), and A Large Ion Collider Experiment (ALICE) collaborations equally well. It is found that both the kinetic freeze-out temperature and transverse flow velocity in the central collisions are comparable with those in the peripheral collisions. With the increase of collision energy from that of the RHIC to that of the LHC, the considered quantities typically do not decrease. Comparing with the central collisions, the proton–proton collisions are closer to the peripheral collisions.

576

A 50 mA CW deuteron RFQ is being built for a joint 973 project between Peking University (PKU) and the Institute of Modern Physics (IMP). This RFQ adopts a high-frequency window-type structure. To study its RF properties and to validate the reliability of an electromagnetic simulation, two full-length aluminum models with tuners were built in succession. RF measurements were obtained from the test bench and compared to the simulations, including frequencies, quality factors, and electric fields of different modes and the field in aperture. Through field tuning, the maximal field unflatness for a single quadrant and the average asymmetry of four quadrants were reduced from 8.7% and ±3.6% to 5.8% and ±1.7%, respectively. Moreover, a tuning method of adjusting the gap distance between the endplates and the vanes was also studied in this paper.

527

Generation of intense, fully coherent radiation with wide spectral coverage has been a long-standing challenge for laser technologies. Several techniques have been developed in recent years to extend the spectral coverage in optical physics, but none of them hold the potential to produce X-ray laser pulses with very high peak power. Urgent demands for intense X-ray light sources have prompted the development of free-electron lasers (FELs), which have been proved to be very useful tools in many scientific areas. In this paper, we give an overview of the basic principle of FELs, techniques for realizing fully coherent FELs, and the development of fully coherent FEL facilities in China.

394

Nanoparticles (NPs) with high-Z atoms have been widely studied as radiosensitizers for use in cancer therapy. Over the past few years, the application of FePt nanoparticles has attracted extensive research interest. Promising results have been obtained, yet limited knowledge is available regarding its potential use as a radiosensitizer. The goal of this study is to investigate the radiosensitization capability of FePt nanoparticle clusters (NPCs) under the exposure of kilovoltage photons using Monte Carlo simulation. First, in order to obtain a realistic distribution of NPCs on the microscopic level, Hela cells were incubated with FePt NPs, and the distribution of NPCs was obtained by optical microscope images and X-ray Nano-CT experiments. Based on these images, a simplified cell model was developed to evaluate the DER of two material types (FePt and FePt₃). For each type, the dependence of DER on the thickness and angular distribution of NPCs on the surface of the cell membrane was studied quantitatively. Our results suggest that DER is strongly dependent on photon energy and the distance from the NPCs to the nucleus. Fe₁Pt₃ is able to achieve a higher DER relative to Fe₁Pt₁. For a given X-ray energy, DER demonstrates an initial increase to a maximum value but gradually saturates as the thickness of NPCs increases from 250 nm up to 2000 nm due to a trapping effect. The impact on DER resulting from the co-existence of the NPCs on the cell membrane and the nuclear membrane was also investigated.

344

A 4H-SiC-⁶³Ni p-n-junction-based betavoltaic battery is investigated. The Monte Carlo method is used to simulate the self-absorption effect of the⁶³Ni source, the backscattering process, and the transport of beta particles in 4H-SiC material. The main factors that affect the energy conversion efficiencies of the cell are analyzed. Based on the simulation results, it can be calculated that, when the thickness of the ⁶³Ni source increases from 2×10^-3 to 10 μm, the theoretical maximum device conversion efficiency increases from 16.77% to 23.51% and the total conversion efficiency decreases from 16.73% to 1.48%. Furthermore, a feasible design with a maximum output power density of 0.36 μW/cm² and an optimal device conversion efficiency of 23.5% is obtained.

477

The goal of this study is to solve the neutron diffusion equation by using a meshless method and evaluate its performance compared to traditional methods. This paper proposes a novel method based on coupling the meshless local Petrov-Galerkin approach and the moving least squares approximation. This computational procedure consists of two main steps. The first involved applying the moving least squares approximation to construct the shape function based on the problem domain. Then, the obtained shape function was used in the meshless local Petrov-Galerkin method to solve the neutron diffusion equation. Because the meshless method is based on eliminating the mesh-based topologies, the problem domain was represented by a set of arbitrarily distributed nodes. There is no need to use meshes or elements for field variable interpolation. The process of node generation is simply and fully automated, which can save time. As this method is a local weak form, it does not require any background integration cells and all integrations are performed locally over small quadrature domains. To evaluate the proposed method, several problems were considered. The results were compared with those obtained from the analytical solution and a Galerkin finite element method (GFEM). In addition, the proposed method was used to solve neutronic calculations in the small modular reactor. The results were compared to those of the citation code and reference values. The accuracy and precision of the proposed method were acceptable. Additionally, adding the number of nodes and selecting an appropriate weight function improved the performance of the Meshless local Petrov-Galerkin method. Therefore, the proposed method represents an accurate and alternative method for calculating core neutronic parameters.

457