Vol.17,

Under three-dimensional plane geometrical constraints ( X,Y, θ), with two asymmetric achromatic sections, the combined three-section structural FODO-like magnet lattice design is adopted and finely optimized in the SSRF electron-beam transfer lines. The magnet lattice has high flexibility and robustness, and the Courant–Snyder parameters can be easily adjusted within a wide range to meet the requirements of transmission and injection for different operation modes of the linear accelerator, booster synchrotron, and storage ring. In this article, the main parameters of the linear optics design of the SSRF electron-beam transfer lines are described, involving the physical design criteria, the total geometrical layout, the magnet lattice, and the beam Courant–Snyder parameters matching. The studies of the variant beam dynamic simulation program calculations show that the design purpose of the efficient beam transmission and injection will be basically achieved.

447

The safety shutter of the SR (synchrotron radiation) facility located at the front end of the facility is an indispensable component for radiation protection. Its thickness is decided by the gas bremsstrahlung produced in the SR facility storage ring by the interaction of electrons with the residual gas molecules in the vacuum chamber of the storage ring. In the calculation, the 3.5GeV, 300mA electron beam and a 15m long insertion-device straight section (0.133μPa) were taken into account, and the safety shutter was assumed to be located 12m away from the end of the straight section. The EGSnrc code based on the Monte-Carlo method and empirical formulas were used, respectively, to calculate the thickness to satisfy the shielding requirement of the safety shutter at the front end of the SR facility, and the results were compared and the availability of EGSnrc was proved.

541

In this work, we investigate the Co-Si reaction, the Co growth mode at room temperature, diffusion behaviour as well as morphology evolution during annealing on both H-terminated and clean Si(001) and Si(111) surfaces. From in-situ X-ray photoelectron spectroscopy (XPS) investigation, "Co-Si" reaction appears to occur on both H-terminated and clean surfaces at room temperature (RT) and the silicide crystallinity is improved upon annealing. Co growth mode on H-terminated Si surfaces occurs in a pseudo layer-by-layer manner while small close-packed island growth mode is observed on the clean Si surface. Upon annealing at different temperatures, Co atom concentration decreases versus annealing time, which in part is attributed to Co atoms inward diffusion. The diffusion behaviour on both types of surfaces demonstrates a similar trend. Morphology study using ex-situ atomic force microscopy (AFM) shows that the islands formed on Si(001) surface after annealing at 700 °C are elongated with growth directions alternate between the two perpendicular [110] and [110] directions. Triangular islands are observed on Si (111) surface.

568

The tobacco leaves were treated with low-temperature plasma in Ar, N₂, O_2, and air atmospheres at different powers (60―130 W). The surface-elemental components, their relative contents, and the functional groups of the surface components of the tobacco leaves were determined using XPS (X-ray photoelectron spectroscopy). The experimental results showed that the percentage of the elements C, N, and O had changed considerably and a large number of polar functional groups containing oxygen atoms were incorporated into the components on the tobacco surfaces. The measurements of the surface contact angle showed that the surface contact angle of the modified tobacco leaves was 0 degree, whereas it was 110 degrees before the plasma treatment. These results indicate that the wettability of the modified tobacco leaves improved dramatically. This work may be significant for future researches on the surface modification of the tobacco leaves.

403

Impulse-coupling coefficients from 1.06-μm, 10-ns Nd:YAG pulsed-laser radiation to GaAs targets with different areas were measured using the ballistic pendulum method in the laser power density ranging from 4.0×10⁸ to 5.0×10⁹W·cm^-2. A detonation wave model of the plasma was established theoretically. The expansion process of plasma after the laser pulse ends is described in detail, and the impulse-coupling coefficients from pulsed laser with different energies to GaAs with different areas were calculated using the given model. It is found that the theoretical results agree well with the experimental data.

419

The aim of this study was to investigate the damage of low-energy ions to HeLa cells and to particularly examine the relationship between apoptotic and necrotic effects and the low-energy ion radiation. In this study, HeLa cells were irradiated by low-energy ions (30keV N⁺) at different doses. The level of apoptosis and necrosis was evaluated using flow cytometry. Since vacuum is required for experimental low-energy ion generation and irradiation, the cells must be placed in vacuum. Mineral oil was used to prevent dehydration of cells. The results show that the apoptotic rate reached 7.09% when the ion implantation dose was 1×10¹⁵ ions/cm²; and when the cells were exposed to and implanted at 2×10¹⁵ ions/cm² dose, the apoptotic rate was higher than that at 1×10¹⁵ ions/cm², and the necrotic rate was 15.63%. In addition, the survival fraction gradually decreased with the increase in implantation dose. Some relationships have been found between the radiation-induced apoptosis and the incubated time after irradiation.

438

In the Morris Water Maze test, high-peak-power pulsed microwave (MW)-exposed rats displayed some learning and memory behavior dysfunctions, and their escape time and swimming distance to the submerged platform were longer than those of the sham-exposed rats. To understand the molecular mechanism involved, the reverse transcription-polymerase chain reaction (RT-PCR) and the Western-blotting technique were used for investigating the mRNA and protein expression patterns of the histamine H₃ receptor (H₃R) in rat hippocampus. High-peak-power pulsed microwave-exposure did not remarkably lead to the change in expression of H₃R mRNA in rat hippocampi; however, it promoted the up-regulatory expression of the H₃R protein, which was possibly triggered through the mitogen-activated protein kinase (MAPK) pathways. Therefore, further investigation of the molecular mechanism of the MW effects on the learning and memory behaviors is required.

473

The front-end conditioner is an essential part of digital systems of nuclear spectrometer, which functions in two ways: (1) prevents saturation of the subsequent ADC; (2) limits the bandwidth of frequency to realize anti-aliasing. To realize the above-mentioned functions, an optimum front-end conditioner for a resistive feedback charge-sensitive preamplifier is designed. In the conditioner, the pole-zero compensation (P/Z compensation) technique was used to effectively filter signals from the preamplifier. The Butterworth filter was improved after the pole-zero position was optimally set up to shape the wave of output, which tallied with the whole system. The front-end conditioner can resolve the aberration of waveform of nuclear signals in a regular Butterworth filter. Compared with the traditional triple-pole filtering circuitry, the circuitry of this conditioner is more compact and flexible. Moreover, its output waveform is more symmetrical and the signal-to-noise ratio (SNR) is higher. The improvement in the resolution of spectrometer is also significant.

514

A two-wavelength pyrometry device using ordinary array CCD (charge coupled device) to collect the radiation data in the horizontal and vertical directions has been developed for measuring the cathode surface temperature during the arc discharge. Analyses of experimental results show that the device can make the measurement of the cathode surface temperature feasible. The cathode surface temperatures measured are lower than the melting point of tungsten (3653 K), and the arc current, cathode diameter, and the cathode length are the main influencing factors of the cathode surface temperature.

454

The pipe holdup measurement is very important for decommissioning nuclear facilities and nuclear-material control and accounting. The absolute detection efficiencies (ε_sp) of full-energy γ rays peak under different source density distribution function have been simulated using the Monte Carlo (MC) software, and the counting rates (n₀) of the characteristic γ rays have been measured using the γ spectrometer followed by the calculation of the holdup. The holdup is affected by the energy of γ rays, distance at which they are detected, pipe material, thickness, and source distribution of pipe, especially source distribution at a short distance. The comparative test of ²³⁵U reference materials on the inner wall of Fe and Al pipes (the total mass of ²³⁵U is 44.6 mg and 222.8 mg, respectively) have been accomplished using this method. The determined result of ²³⁵U is 43.2mg (U_0.95rel=5.4%) and 216.2mg (U_0.95rel=3.2%), respectively, which are in accordance with the reference values.

538

In the development of the Severe Accident Management Guidelines (SAMG), it is very important to choose the main severe accident sequences and verify their mitigation measures. In this article, Loss-of-Coolant Accident (LOCA), Steam Generator Tube Rupture (SGTR), Station Blackout (SBO), and Anticipated Transients without Scram (ATWS) in PWR with 300 MWe are selected as the main severe accident sequences. The core damage progressions induced by the above-mentioned sequences are analyzed using SCDAP/RELAP5. To arrest the core damage progression and mitigate the consequences of severe accidents, the measures for the severe accident management (SAM) such as feed and bleed, and depressurizations are verified using the calculation. The results suggest that implementing feed and bleed and depressurization could be an effective way to arrest the severe accident sequences in PWR.

533

An experimental research on the dryout point of flow boiling in narrow annular channels under low mass flux with 1.55mm and 1.05mm annular gap, respectively, is conducted. Distilled water is used as working fluid and the range of pressure is limited within 2.0~4.0MPa and that of mass flux is 26.0~69.0kg·m^-2·s^-1. The relation of critical heat flux (CHF) and critical qualities with mass flux and pressure are revealed. It is found that the critical qualities decrease with the increasing mass flux and increase with the increasing inlet qualities in externally heated annuli. Under the same conditions, critical qualities in the outer tube are always larger than those in the inner tube. The appearance of dryout point in bilaterally heated narrow annuli can be judged according to the ratio of q_o/q_i.

446