Vol.25,

Photocathode RF gun is widely used for particle accelerators as an electron source. When driving an RF electron gun at the fundamental frequency and a higher harmonic frequency simultaneously with proper field ratio and relative phase, it generates electron beams of ultralow emittance and a linear longitudinal phase space distribution. Such a gun provides high quality electron beam with low energy spread, small traverse emittance and high brightness. In this paper, the RF design of a 1.5 cell cavity is presented. Simulation results of beam dynamics for the two-frequency gun and a standard single-frequency RF gun are also shown in this paper. In addition, bunch compression with a two-frequency gun is explored.

604

Hydrostatic leveling system (HLS) is widely used in precision engineering survey, especially the alignment of particle accelerator, and the tidal effects on the measurement accuracy of HLS is non-ignorable, thus studies on tidal effects on the HLS is vital. A set of HLS was installed in Jingxian seismostation for verifying the methods to handle the tidal effects on the readings of HLS. Harmonic analysis of the data recorded by HLS and DSQ water tube clinometers in Jingxian seismostation and contrastive analysis of the results are completed. The tilt tide can be well reflected in the data of the both instruments and the results are both reliable. The reasons of the difference between the results are analyzed in this paper. Besides, a validation study based on the measurement data of the HLS used in SPring-8 storage ring for tidal correction on the reading of HLS is completed. The research establishes a foundation for HLS to be applied in micron-level precision alignment of particle accelerator in the future.

487

External micro-PIXE measurements were done to investigate the accumulation of Nd³⁺ on green algae species euglena gracilis. According to the Nd distribution patterns in the gracilis cells, the biosorption of Nd³⁺ to the cell’s compartments can be observed. Comparing elemental mappings of the cell treated with different doses of the 1 mg/mL Nd³⁺ solution, the Nd uptake of euglena gracilis cells do no relate with the doses. From distributions of Ca and Mg, it is found that the Ca is complementary to Nd partly, and the Nd and Mg distributions are alike to each other, showing that Nd may be mainly in the chlorophyll molecules. The biochemistry related is discussed.

630

In this paper, equivalent energy method is introduced for measuring mass thickness of dual-component samples using dual-energy X-rays. Approximately, the method adopts equivalent mass attenuation coefficients of the two components in mass thickness measurements for dual-component samples, in a certain range of thicknesses. Feasibility of the method is proven by numerical calculations and Monte Carlo simulations (EGSnrc package). The results of absorption experiments using an X-ray machine at tube voltages of 30 and 45 kV, the relative errors are less than 5% between the nominal and detected values. Also, optical low energy is discussed at given high voltages.

715

475

A novel extractant, N,N’-dimethyl-N,N’-didecyl-3-oxa-diglycolamide (DMDDDGA), was designed and synthesized for extraction of lanthanides in the nuclear fuel reprocessing. The extraction behaviors of Gd, Dy, Er and Ho from nitric acid solution were investigated using DMDDDGA in chloroform. The effects of nitric acid concentration, extractant concentration, and temperature on the extraction were investigated. The distribution ratio of lanthanides increases with concentrations of the extractant and nitric acid, but decreases with increasing temperature, which indicates that the extraction process is exothermic. FT-IR spectra indicated that the C=O in DMDDDGA is coordinated with metal ion in the extracted species and the stoichiometries of lanthanides(III) complex are Gd(NO₃)₃⋅3DMDDDGA, Dy(NO₃)₃⋅4DMDDDGA, Er(NO₃)₃⋅4DMDDDGA, and Ho(NO₃)₃⋅4DMDDDGA.

688

Extensive accumulation of neurofibrillary tangles (NFTs) consistently correlate with the degree of cognitive impairment and neuronal circuitry deterioration associated with Alzheimer’s disease. However, no PET probe is currently available for selective detection of NFTs in the living human brain. [¹⁸F]-THK523 was developed as a potential in vivo imaging probe for tau pathology. In this paper, we report a new protected precursor, 2-((2-(4-(( tert-butoxycarbonyl)amino)phenyl)quinolin-6-yl)oxy)ethyl 4-methylbenzenesulfonate (THK-7), instead of 2-((2-(4-aminophenyl)quinolin-6-yl)oxy)ethyl 4-methylbenzenesulfonate (BF241), and an improved automated radiosynthesis of [¹⁸F]-THK523 and the study on chemical kinetics of the labeling reaction of [¹⁸F]-THK523, with high-yield (70±5%, n=6, decay-corrected to end of bombardment), and high radiochemical purity (>90%) and specific activity (2.5 ± 0.5 Ci/μmol) from protected precursor on fully automated module at the end of radiosynthesis (45–55 min). The chemical kinetics for [¹⁸F]-THK523 demonstrates that nucleophilic substitution can be carried out easily with protected precursor.

573

The existing ²¹⁰Pb_ex mass balance models for the assessment of cultivated soil erosion are based on an assumption that ²¹⁰Pb_ex is quite evenly mixed within the plough layer. However, the amount of ²¹⁰Pb_ex distributed in the soils below the plough depth, like a downward tail in the lower part of the ²¹⁰Pb_ex profile, has been largely ignored. In fact, after the initial cultivation of undisturbed soils, ²¹⁰Pb_ex will diffuse downward from plough layer to the plough pan layer due to the concentration gradient. Assuming ²¹⁰Pb_ex inventory is constant, the depth distribution in the two layers of the cultivated soils will achieve a steady state after continuous cultivation for 10.37 years, when ²¹⁰Pb_ex is evenly distributed in the soils of the plough layer with an exponential concentration decline with depth in the soils of the plough pan layer, and the ²¹⁰Pb_ex concentration at any depth will be invariable with time. The work reported in this paper attempts to explain the formation of the ²¹⁰Pb_ex tail in the soil profile below the plough depth by theoretical derivation of the ²¹⁰Pb_ex depth distribution process in the two layers of the cultivated soils, propose a ²¹⁰Pb_ex mass balance model considering ²¹⁰Pb_ex diffusion based on the existing model, and discuss the influence of the ²¹⁰Pb_ex tail to the existing model.

722

In order to realize on-line real-time measurement of dynamic and time-sharing neutron spectrum of HL-2A, a tokamak fusion neutron spectrometer based on PXI bus was developed. It consists of electronics system and eight thermal neutron detectors, namely SP9 ³He proportional counter, embedded in eight polyethylene spheres in different diameters. Response function of the eight polyethylene spheres was the key to calculate the neutron spectrum accurately. In this paper, response function of the eight polyethylene spheres is simulated by adopting Geant4 code, and neutron counts from an ²⁴¹Am-Be neutron source are measured by the eight detectors. The calculated spectrum of the Am-Be neutron is accurate in 0–2 MeV region, and is similar to the theoretical spectrum. The tokamak fusion neutron spectrometer was used in HL-2A device to monitor the dynamic neutron spectrum of HL-2A on-line and real-time.

803

A readout electronics has been developed for the silicon strip array detector system of HIRFL-CSR-ETF. It consists of 48 front end electronics (FEE) boards, 12 PXI-DAQ boards and one trigger board. It can implement energy and time measurements of 4608 channels. Each FEE board is based on 6 ASICs (ATHED), which implements energy and time measurements of 96 channels. The PXI-DAQ board meets requirements of high-speed counting and amount of readout channels and can process signals of 4 FEEs. The trigger board is developed to select the valid events. The energy linearity of the readout electronics is better than 0.3% in the dynamic range of 0.1–0.7 V. In the test with a standard triple alpha source, the energy resolution was 1.8% at 5.48 MeV. This readout electronics enables the silicon strip array system to identify particles of A 14.

515

The neutron induced reactions on stable Carbon, Nitrogen, and Oxygen isotopes are investigated by using the Talys1.4 toolkit with the default parameters. The neutron incident energy covers a range from 0.20 MeV to 85.00 MeV. For ¹²C and ¹⁴N, the Talys1.4 results agree with the experimental data, while the parameters should be adjusted for ¹⁶O. Some E_n windows are found by comparing the main channels of n + C/N/O reactions, which induce element change. In these E_n windows, a specific element is activated to a different one while leaving the other element atoms unchanged. The results will facilitate the research of doping effects in organic materials by using neutron activation technique.

657

Experiments at the Large Hadron Collider (LHC) have measured multiplicity distributions in p+p and p+Pb collisions at a new domain of collision energy. Based on considering an energy-dependent broadening of the nucleon’s density distribution, charged hadron multiplicities are studied with the phenomenological saturation model and the evolution equation dependent saturation model. By assuming the saturation scale has a small dependence on the 3-dimensional root mean square (rms) radius at different energy, the theoretical results are in good agreement with the experimental data from CMS and ALICE collaboration. The predictive results in p+p collisions at s=14 TeV of the LHC are also given.

502

Bio-nanosensors (Bio-NSs) have attracted much attention recently due to their unique properties. Among all of the bio-NSs, the intracellular proton sensor is significant for biomedicine studies and clinic diagnosis. Proton nanosensors (PNSs) with different pH sensitive ranges could satisfy different research requirements. Here we report a facile method to build a PNS with a neutral to basic pH sensitive range, in which the commercial pH indicator, fluoresceinamine (FA), was covalently coupled to the carboxylic-rich amphiphilic polymer (AP) coated gold nanoparticles (AuNPs).

634

In this paper, we study hydrodynamics and thermal behaviors of micro-heat exchanger of different cross sections, with hydraulic diameters (D_h) of 0.4–0.8 mm and Reynolds numbers (Re) of 300–900. Validity of the model is proved by comparing simulation results based on classical Navier-Stokes equations with experimental data and Tuckerman correlation. Effects of dynamic viscosity, hydraulic diameter, Reynolds number and cross section of the micro-channels are investigated. The results indicate that the variable viscosity effect should be taken into account, and rod bundle micro-channels have the highest heat transfer coefficient of the three types of micro-channels.

467

In order to provide data on diffusion coefficients and solubility constants of tritium in molten salts for the critical issue of tritium control in the Thorium Molten Salt Reactor (TMSR) program, a two-chamber permeability apparatus separated by a nickel plate had been developed for determining the permeability of hydrogen isotope in molten salts. Descriptions on the permeability apparatus, experimental procedure and the analytical method for determining the diffusivity and solubility of hydrogen isotope in molten salts were presented in this paper. To assess the performance of the apparatus, the blank tests without molten salt were conducted at 300–700 ℃. The results showed that the nickel plate acting as the window for hydrogen isotope permeation in the apparatus seemed to have less effect on experiments of determining the permeability of hydrogen isotope in molten slat at 500–700 ℃. Furthermore, the applicability of the apparatus with molten salt was also evaluated experimentally, with test experiments of molten Flinak (LiF-NaF-KF) at 500 ℃, 600 ℃ and 700 ℃. Diffusion coefficients and solubility constants of hydrogen in molten Flinak can be derived from those test experiments, which were correlated toDFlinak−H=7.06×10−5e−54.9/(RgT)m²/s andSFlinak−H=1.67×10−7e27.0/(RgT)mol-H₂/(m³ Pa).

681

A nuclear battery consisting of a beta source, a phosphor layer and a photovoltaic device was prepared. Planar phosphor layers were synthesized through physical precipitation of ZnS:Cu, ZnS:Ag or SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors. The radioluminescence (RL) spectra were used to analyze the RL effects of the phosphor layers under beta-particle excitation. Feasibility of using the materials as intermediate absorbers in the beta batteries was studied. The I–V characteristics of beta RL nuclear batteries with different phosphor layers were tested using ⁶³Ni or ¹⁴⁷Pm beta sources. The output power of zinc sulfide matrix phosphor layer was better than that of rare-earth element oxides. In addition, a thin aluminum reflective layer was vacuum-evaporated on the phosphor layers to improve the efficiency of beta RL nuclear batteries, and the results were discussed.

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