In this paper, higher order modes (HOMs) and loss factor of a new type of 500-MHz superconducting cavity is studied, by simulating its broadband HOMs damping at different positions of the ferrite HOM-absorber and different lengths of the ferrite. The results show that the impedance and Q value of the HOMs in transverse and longitudinal modes could be greatly reduced. The HOM longitudinal impedance could be damped to meet the requirement of SSRF beam instability threshold. The calculated loss factor of the new SC cavity was compared with cavities at SSRF. It was estimated that the HOM absorber could absorb a total power of 3.16 kW at 4-mm beam bunch length.
Vol.22, No.5
Select issueYearIssue
2011
5
SYNCHROTRON TECHNOLOGY AND APPLICATIONS
Research article 20 Oct 2011
YU Haibo，Jian-Fei Liu，HOU Hongtao，LU Changwang，WEI Yelong，MA Zhenyu，FENG Ziqiang，MAO Dongqing
keyword：Superconducting RF；HOM absorber；Loss factor；
Research article 20 Oct 2011
CHEN Zhichu，Yong-Bin Leng，ZOU Yi，YAN Yingbin，ZHOU Weimin
The top-up injection mode of Shanghai Synchrotron Radiation Facility (SSRF) needs precise measurement of the beam bunch charges. This is performed by an integration current transformer, but the beam current is too low to neglect the background noise. In order to wipe out the noise coming from the ground loops, the adaptable polynomial fitting method is used to extract the baseline, instead of using the constant background or the linear background model. Test results show that the system resolution can be improved to <3%.
keyword：Beam diagnostics；ICT；Bunch charge monitor；Top-up；SSRF；
LOW ENERGY ACCELERATOR AND RADIATION APPLICATIONS
Research article 20 Oct 2011
FU Min，TANG Zhenan
The time and efficiency of charge collection are the key factors of monolithic active pixel sensor devices for minimum ionizing particles tracking detection. In this paper, 3D models of pixels with different resistivity epitaxial layers (epi-layers) are built and simulated using Synopsys-Sentaurus. The basic characteristics of detectors are evaluated, including electric potential, electric field, and depleted region. Results indicate that the high resistivity (HR) epi-layer is a better choice. Further, simulation results show that the key collection performance is significantly improved owing to a wider and stronger electric field in the N type HR epi-layer.
keyword：Monolithic active pixel sensor；Charge collection；High resistivity；Simulation；
Research article 20 Oct 2011
YUAN Gang，GAO Jing，SUN Xuhui，ZHOU Xingtai
In2O3 nanowires with uniform morphology and single crystalline structure were synthesized at low temperature of 400ºC~450ºC using InSb as the precursor via VLS mechanism. The nanowires have uniform diameter of about 40 nm and are up to tens of micrometres in length and grew along the [100] direction as established by high resolution electron microscopy. The electronic and local structures of In2O3 nanowires, compared to that of In2O3 powder, have been studied with X-ray absorption fine structure (XAFS) at In K-edge and O K-edge. The XAFS results reveal the stronger In-O bonding in In2O3 nanowires compared to bulk In2O3.
keyword：In2O3 nanowires；Low temperature synthesis；XAFS；Electronic structure；
Research article 20 Oct 2011
Gang Xu，REN Hua，WU Ming-Hong，LIU Ning，YUAN Qing，TANG Liang，WANG Liang
E-beam degradation of bisphenol A (BPA) was carried out, under reductive condition of ethanol-water solution and oxidative condition of acetonitrile-water solution. The degradation efficiency is higher in oxidative condition than that in reductive condition, and increases with the dose but decreased with increasing initial concentration. The BPA radiolysis follows the pseudo-first-order kinetics. Adding H2O2, or neutral condition, does not benefit BPA degradation in oxidative conditions. Pulsed radiolysis was used to investigate mechanism of the BPA radiolysis. The rate constant for BPA reaction with ·OH (1.85×1010 L·mol–1·s–1) is about an order of magnitude higher than that with e–aq (1.80×109 L·mol–1·s–1). The degradation products were analyzed by ion chromatograph. Smaller molecules such as formic acid and acetic acid were detected, indicating that ·OH attacks the BPA molecule. The work is of significance for the practical E-beam treatment of waste water containing BPA.
keyword：Bisphenol A；E-beam irradiation；Degradation；Pulsed radiolysis；
Research article 20 Oct 2011
LI Yongqiang，SATOH Takahiro，DU Hanwen，ZHENG Yi，LI Xinyi，LIU Bo
In this paper, we report a novel measurement system based on the development of Fudan Scanning Proton Microscopy (SPM) facility. By using Si-PIN diode (Hamamatsu S1223-01) detector, scanning transmission ion microscopy (STIM) measurement system has been set up. It can provide density and structural images with high probing efficiency and non-destruction by utilizing the energy loss of high energy (MeV) and focused ions penetrating through a thin sample. STIM measurement is able to map the density distribution of organic elements which mostly compose biology materials, such information can not be detected by using conventional Be-windowed Si (Li) X-ray detector in Particle Induced X-ray Emission (PIXE) technique. The spatial resolution capability of STIM is higher than PIXE technique at same accelerator status. As a result of STIM measurement, paramecium attached on the top of Kapton tube was measured by STIM.
keyword：Energy loss；STIM；PIXE；Spatial resolution；Computed tomography；
Research article 20 Oct 2011
SUN Hongchao，NI Bangfa，XIAO Caijin，ZHANG Guiying，LIU Cunxiong，HUANG Jinfeng
In this paper, computational methods are used to optimize the design of a prompt-gamma neutron activation analysis (PGNAA) system on China Advanced Research Reactor (CARR). Approaches are adopted for obtaining accurate neutron beam parameter and saving the computing time. For the radiation shielding design, the optimizing factors include the cost, weight, volume, machining convenience and background radiation at the detector position. Low background spectrum and high sensitivity are expected. The simulation results, and experiences from international PGNAA community, were used in the design of the CARR PGNAA system.
keyword：Prompt gamma activation analysis；PGAA Facility；Neutron Cross-section；Shielding；
RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE
Research article 20 Oct 2011
DENG Shengming，ZHANG Bin，WU Yiwei，ZHANG Wei
It is essential to predict the treatment efficacy of pancreatic carcinoma early. The purpose of this study was to examine whether 18F-FDG (2’-deoxy-2’-[18F]fluoro-D-glucose) or 18F-FLT (3’-deoxy-3’-18F-fluorothymidine) PET can be used for chemosensitivity testing by investigating the binding characteristic of 18F-FDG or 18F-FLT with Patu 8988 human pancreatic carcinoma cell and the influence of gemcitabine in the uptake of 18F-FDG or 18F-FLT on Patu 8988. Under the conditions of 1×106 cells, 3.7 kBq 18F-FDG or 18F-FLT, and incubation at 37ºC for 100 min, the cell uptake of 18F-FDG and 18F-FLT was (60.60±3.05)% and (50.57±2.81)%, respectively. There was a significant decrease in TK1-LI (thymidine kinase 1 labeling index) 24 h after administration of gemcitabine. The uptakes of 18F-FDG and 18F-FLT were negatively correlated with the doses of gemcitabine (r= –0.928 for 18F-FDG, r= –0.876 for 18F-FLT, P<0.01). When same doses of gemcitabine were administered, the 18F-FLT uptake inhibition rate was significantly higher than that of 18F-FDG (P<0.01). These results indicate that the response to gemcitabine could be predicted as early as 24 h by 18F-FDG or 18F-FLT PET scans. 18F-FLT is more sensitive than 18F-FDG to predict the response to therapy.
keyword：Pancreatic carcinoma；Uptake；Gemcitabine；18F-FDG；18F-FLT；
NUCLEAR, HEAVY ION AND ATOMIC PHYSICS
Research article 20 Oct 2011
SUN Peijian，Ping Huai，ZHANG Wei，CHENG Cheng，ZHU Zhiyuan
In order to understand the effects of electron-phonon coupling and Coulomb interactions in angle-resolved photoemission spectroscopy (ARPES), a spin-1/2 Hubbard-Holstein model at half-filling is theoretically investigated by means of the mean field theory and classical Monte Carlo simulation method. It shows that the spectral shape of the one-dimensional system is significantly modified by the electron-phonon coupling and Coulomb interactions. The suppression of charge-density wave in one-dimensional system has been ascribed to the short-range Coulomb repulsion and thermal lattice fluctuations. The competition between these interactions can induce zero energy gaps in APPES as well as complete cancellation of charge or spin ordering.
keyword：ARPES；Electron-phonon coupling；Electron-electron interaction；Monte Carlo simulation；
Research article 20 Oct 2011
XIE Feng，HE Xiaobing，JIANG Wengang，CHEN Zhanying，SHI Quanlin，CHANG Yongfu
In preparation of homogeneous 88Kr and 88Rb sources, the 88Kr activity was determined by the decay relationship between 88Kr and 88Rb using an HPGe detector. The peak efficiencies of 88Kr and 88Rb γ-rays were calibrated. The results show that the absolute probabilities of 196.3, 834.8,1529.8, 2195.8 and 2392.1 keV γ-rays of 88Kr were 25.1(5)%, 12.9(2)%,10.7(2)%,13.3(2)% and 34.9(5) %, respectively.
keyword：Kr-88 and Rb-88；Gamma-ray emission probability；Decay relationship；Activity；Peak efficiency；
INTERDISCIPLINARY STUDIES OF NUCLEAR PHYSICS
Research article 20 Oct 2011
XU Wei，TU Yusong，Wang Chunlei，FANG Hai-Ping
The effect of an external charge on water transportation through T-shaped carbon nanotubes is tested by molecular dynamics simulations. The simulation results show that a relatively small charge reduces the water flux through the canbon nanotubes, but a large enough charge prompts the water transportation. This finding may be helpful to biological amplifiers and nanodevices researches.
keyword：External charge；T-shaped nanotube；Water transportation；
NUCLEAR ENGINEERING
Research article 20 Oct 2011
Alrwashdeh MOHAMMAD，YU Ganglin，WANG Kan
This work is aimed at running the first IRIS reactor core with mixed thorium dioxide fuel (ThO2-UO2 and ThO2-PuO2). Calculations are performed by using Dragon 4.0.4 and Citation codes. The results show the multiplication factor (Keff) for central and peripheral assemblies as a function of burnup. To ensure the proliferation resistance, the value of 235U enrichment is ≤ 20%. The Keff is calculated using Dragon 4.0.4 for a single fuel rod and the model developed to fuel assembly, while the whole core was calculated using Citation code. For a fuel burnup, the use of increased enrichment fuel in the IRIS core leads to high reserve of reactivity, which is compensated with an integral fuel burnable absorber. The self-shielding of boron is in an IRIS reactor fuel. The effect of increased enrichment to the burn-up rates, and burnable poison distribution on the reactor performance, are evaluated. The equipment used in traditional light water reactors is evaluated for designing a small unit IRIS reactor.
keyword：Long life reactor；High burnup；Burnable absorber；
Research article 20 Oct 2011
ZHOU Tao，SUN Canhui，LI Zhenyang，WANG Zenghui
Human factor errors in probabilistic safety assessment (PSA) of a nuclear power plant (NPP) can be prevented using thermal comfort analysis. In this paper, the THERP+HCR model is modified by using PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied) index system, so as to obtain the operator cognitive reliability, and to reflect and analyze human perception, thermal comfort status, and cognitive ability in a specific NPP environment. The mechanism of human factors in the PSA is analyzed by operators of skill, rule and knowledge types. The THERP+HCR model modified by thermal comfort theory can reflect the conditions in actual environment, and optimize reliability analysis of human factors. Improving human thermal comfort for different types of operators reduces adverse factors due to human errors, and provides a safe and optimum decision-making for NPPs.
keyword：Thermal comfort；PSA；Nuclear safety；
