Modification of ZnO films under high energy Xe-ion irradiations

ZnO films were deposited on (100) Si substrate by radio frequency magnetron sputtering. These films were irradiated at room temperature with 308 MeV Xe-ions to a fluence of 1.0 x 10(12), 1.0 x 10(13) or 1.0 x 10(14) Xe/cm(2). Then the samples were investigated using RBS, XRD, FESEM and PL analyses. The obtained experimental results showed that the deposited ZnO films were highly c-axis orientated and of high purity, 308 MeV Xe-ion irradiations could not change the c-axis oriented. The topography and PL properties of the ZnO films varied with increasing the Xe-ion irradiation fluence. For 1.0 x 10(13) or 1.0 x 10(14) Xe/cm(2) irradiated samples, surface cracks were observed. Furthermore, it was found that the 1.0 x 10(14) Xe/cm(2) irradiated sample exhibiting the strongest PL ability. The modification of structure and PL properties induced by 308 MeV Xe-ion irradiations were briefly discussed. (C) 2008 Elsevier B.V. All rights reserved.

Beam dynamics design of an RFQ for a planned accelerator, which uses a direct plasma injection scheme

To meet the requirements of providing high-intensity heavy ion beams the direct plasma injection scheme (DPIS) was proposed by a RIKEN-CNS-TIT collaboration. In this scheme a radio frequency quadrupole (RFQ) was joined directly with the laser ion source (LIS) without a low-energy beam transport (LEBT) line. To find the best design of the RFQ that will have short length, high transmission efficiency and small emittance growth, beam dynamics designs with equipartitioning design strategy and with matched-only design strategy have been performed, and a comparison of their results has also been done. Impacts of the input beam parameters on transmission efficiency are presented, too. (C) 2008 Elsevier B.V. All rights reserved.

Structural and PL properties of Cu-doped ZnO films

Cu-doped ZnO films with hexagonal wurtzite structure were deposited on silicon (1 1 1) substrates by radio frequency (RF) sputtering technique. An ultraviolet (UV) peak at similar to 380nm and a blue band centered at similar to 430nm were observed in the room temperature photoluminescent (PL) spectra. The UV emission peak was from the exciton transition. The blue emission band was assigned to the Zn interstitial (Zn-i) and Zn vacancy (V-Zn) level transition. A strong blue peak (similar to 435 nm) was observed in the PL spectra when the alpha(Cu) (the area ratio of Cu-chips to the Zn target) was 1.5% at 100 W, and ZnO films had c-axis preferred orientation and smaller lattice mismatch. The influence of alpha(Cu) and the sputtering power on the blue band was investigated.

A Particle-in-cell scheme of the RFQ in the SSC-Linac

A 52 MHz Radio Frequency Quadrupole (RFQ) linear accelerator (linac) is designed to serve as an initial structure for the SSC-Linac system (injector into Separated Sector Cyclotron). The designed injection and output energy are 3.5 keV/u and 143 keV/u, respectively. The beam dynamics in this RFQ have been studied using a three-dimensional Particle-In-Cell (PIC) code BEAMPATH. Simulation results show that this R,FQ structure is characterized by stable values of beam transmission efficiency (at least 95%) for both zero-current mode and the space charge dominated regime. The beam accelerated in the RFQ has good quality in both transverse and longitudinal directions, and could easily be accepted by Drift Tube Linac (DTL). The effect of the vane error and that of the space charge on the beam parameters have been studied as well to define the engineering tolerance for RFQ vane machining and alignment.

Study on shunt impedance and voltage distribution of 4-rod RFQ cavity

A high current RFQ (radio frequency quadrupole) is being studied at the Institute of Modern Physics, CAS for the direct plasma injection scheme. Shunt impedance is air important parameter when designing a 4-rod RFQ cavity, it reflects the RF efficiency of the cavity, and has a direct influence on the cost of the structure. Voltage distribution of a RFQ cavity has an effect on beam transmission, and particles would be lost if the actual voltage distribution is not as what, it should be. The influence of cell length, stern thickness and height on Shunt impedance and voltage distribution have been studied, in particular the effect of projecting electrodes has been investigated in detail.

Drift distance survey in direct plasma injection scheme for high current beam production

In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C6+ beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance.

The Compact Pulsed Hadron Source: A Design Perspective

During the past. decades, large-scale national neutron sources have been developed in Asia, Europe, and North America. Complementing such efforts, compact hadron beam complexes and neutron sources intended to serve primarily universities and industrial institutes have been proposed, and some have recently been established. Responding to the demand in China for pulsed neutron/proton-beam platforms that are dedicated to fundamental and applied research for users in multiple disciplines from materials characterization to hadron therapy and radiography to accelerator-driven sub-critical reactor systems (ADS) for nuclear waste transmutation, we have initiated the construction of a compact, yet expandable, accelerator complex-the Compact Pulsed Hadron Source (CPHS). It consists of an accelerator front-end (a high-intensity ion source, a 3-MeV radio-frequency quadrupole linac (RFQ), and a 13-MeV drift-tube linac (DTL)), a neutron target station (a beryllium target with solid methane and room-temperature water moderators/reflector), and experimental stations for neutron imaging/radiography, small-angle scattering, and proton irradiation. In the future, the CPHS may also serve as an injector to a ring for proton therapy and radiography or as the front end to an ADS test facility. In this paper, we describe the design of the CPHS technical systems and its intended operation.

CSRm高频系统控制器

HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）是国家重大科学工程，其控制系统是一个庞大的系统，由许多分控制系统组成，高频系统是其重要组成部分之一。加速器的加速过程都是由高频系统来完成的。由于高频控制系统的控制对象就是高频腔体，控制系统的稳定性和输出频率的精确性将直接影响到加速器系统的正常工作，而对于高频系统的状态回读又直接决定了对于高频系统的远程监控能力，所以高频控制系统的设计非常重要。本设计基于现场可编程逻辑门阵列FPGA和数字信号专用处理器DSP搭建， 一方面可以完成从控制中心远程控制高频腔体，另一方面也可以完成对于当前状态的读取，所经过的通道也是多样化的，包括CPCI总线通信，CANBUS总线通信或者是485总线通信。本文的内容包括了1>对于高频控制系统控制对象的分析以及各种控制参数要求。2>组成此系统的硬件部分分析选择以及硬件系统的搭建过程。3>对FPGA和DSP进行程序设计的过程和方法。本文的价值不仅在于对高频系统的控制上，对于其他数据采集系统，远程控制系统以及总线通信和数据分析算法上也有着参考价值

SFC200KW高频发射机控制系统改造

本文全面论述了一个基于PROFIBUS现场的总线分布式控制系统的设计、开发、调试过程，详细介绍了控制系统的结构和软硬件设计。论文从SFC200KW高频发射机控制需求出发，阐明了控制系统的开发背景、基本结构的建立、硬件接口电路的设计方案、控制算法的设计思想以及上下位机控制程序的实现。论文分四大部分，首先介绍SFC200KW高频发射机控制系统的现状，阐明进行SFC200KW高频发射机控制系统改造的必要性和采用现场总线分布式控制系统的优势。第二部分介绍控制系统改造的相关技术。第三部分结合PROF工BUS和FCS控制系统理论详细介绍了新SFC200KW高频发射机控制系统的结构，包括主控器PLC实时控制、系统抗干扰特性、电平转换接口等。第四部分结合SFC200KW高频发射机控制算法，下位机PLC编程语言，介绍了控制系统软件的设计和开发。上位机监控程序采用W工NCC组态软件完成友好的人机交互界面开发。通过对该控制系统的改造，满足了工程对控制部分可靠性、实时性和稳定性的需求。实现了对SFC200KW高频发射机远程控制，运行参数实时采集，故障实时保护和报警记录，运行参数归档和打印等功能。达到了改造的目的。

CSR数字射频系统的同步算法研究与应用

本文要解决CSR控制系统中扮制信号同步传送问题。HIRFL_CSR(Heavy Ion Research Facility at LanKZhou-Cooling StorageRing兰州重离子冷却储存环）是国家九八爪大科学工程之一，它的控制是一个非常庞大而复杂的系统，它由多个子系统构成，各个子系统之间的协调同步是HIRFL-CSR运行的关键，也是HIRFL-CSR从控制系统的核心问题之一。。CSR工程的同步系统包括环内各设备之间的同步，环与门前端务器的同步等等。同步系统的实现应该在保证协调同步的雄础上，还要保证整个控制系统的稳定性，实时性，准确性和抗干扰性。本文的披个解决方案是建立在直按序列扩频通信技术上的。扩频通信系统可以增强控制信一号的抗干扰性，完成f言号的可靠传输。在信号发送端，进行恭带信号的载波调制，然后经过pN码的扩频调制，进入信道传输；在接收端，先进行四码的解扩一，然后进行载波信号的解调，还原为发送端的信号。在整个过程中保证CSI又控制信号的同步，包括载波同步，位同步和群同步。本文主要工作和研究内容是CSR系统中的载波同步传输算法的不开究，设计和实现。主要工作包括（1）不叶究控制洁号在通信算法中的性能，在算法分析的基础上，使用MATLAB实现模拟控制信号通信过程，同时进行传送信号分析和噪声功率分析，测试可行性:(2)在仿真可行的情况下，把整个通信过程全部或者部分写为可以执行的C或者汇编代码，在TMS323C6711DSK板进行程序调试；（3）把可执；行的释序下我到以TrAG为接口白如醚件协尔32C6713DSP模块，实现在CSR系统中控制信号的传送。本文目的是解决控制信号的同步通愉问题，对于该问题的传输分析和同步实现以及提出的下一步研究，在C双控制I具有很重要的意义，同时也对于类似问题的解决有重要价值。

A plasma sputtering decoration route to producing thickness-tunable ZnO/TiO2 core/shell nanorod arrays

We report a radio frequency magnetron sputtering method for producing TiO2 shell coatings directly on the surface of ZnO nanorod arrays. ZnO nanorod arrays were firstly fabricated on transparent conducting oxide substrates by a hydrothermal route, and subsequently decorated with TiO2 by a plasma sputtering deposition process. The core/shell nanorods have single-crystal ZnO cores and anatase TiO2 shells. The shells are homogeneously coated onto the whole ZnO nanorods without thickness change. This approach enables us to tailor the thickness of the TiO2 shell for desired photovoltaic applications on a one-nanometer scale. The function of the TiO2 shell as a blocking layer for increasing charge separation and suppression of the surface recombination was tested in dye-sensitized solar cells. The enhanced photocurrent and open-circuit voltage gave rise to increased photovoltaic efficiency and decreased dark current, indicating successful functioning of the TiO2 shell.

The effects of shell characteristics on the current-voltage behaviors of dye-sensitized solar cells based on ZnO/TiO2 core/shell arrays

The ZnO/TiO2 core/shell structure was formed through deposition of a TiO2 coating layer on the hydrothermally fabricated ZnO nanorod arrays through radio frequency magnetron sputtering. The effects of the TiO2 shell's characteristics on the current-voltage behaviors of the core/shell-based dye-sensitized solar cells (CS-DSSC) were investigated. As the rates of injection, transfer, and recombination of electrons of such CS-DSSC were affected significantly by the crystallization, morphology, and continuity of the TiO2 shells, the photovoltaic efficiency was accordingly varied remarkably. In addition, the efficiency was further improved by enhancing the surface area in the core/shell electrode.

A study of the RF characteristics for wireless sensor deployment in building environment

In this paper, The radio Frequency (RF) Monitoring and Measurement of the Environmental Research Institute (ERI) located in Cork city will be monitored and analyzed in both the Zigbee (2.44 GHz) and the industrial, scientific and medical (ISM 433 MHz). The main objective of this survey is to confirm what the noise and interferences threat signals exist in these bands. It was agreed that the surveys would be carried out in 5 different rooms and areas that are candidates for the Wireless Sensors deployments. Based on the carried on study, A Zigbee standard Wireless Sensor Network (WSN) will be developed employing a number of motes for sensing number of signals like temperature, light and humidity beside the RSSI and battery voltage monitoring. Such system will be used later on to control and improve indoor building climate at reduced costs, remove the need for cabling and both installation and operational costs are significantly reduced.

Phase estimation receiver for full-field detection: a novel receiver structure for electronic dispersion compensation of metropolitan area networks

The development of ultra high speed (~20 Gsamples/s) analogue to digital converters (ADCs), and the delayed deployment of 40 Gbit/s transmission due to the economic downturn, has stimulated the investigation of digital signal processing (DSP) techniques for compensation of optical transmission impairments. In the future, DSP will offer an entire suite of tools to compensate for optical impairments and facilitate the use of advanced modulation formats. Chromatic dispersion is a very significant impairment for high speed optical transmission. This thesis investigates a novel electronic method of dispersion compensation which allows for cost-effective accurate detection of the amplitude and phase of the optical field into the radio frequency domain. The first electronic dispersion compensation (EDC) schemes accessed only the amplitude information using square law detection and achieved an increase in transmission distances. This thesis presents a method by using a frequency sensitive filter to estimate the phase of the received optical field and, in conjunction with the amplitude information, the entire field can be digitised using ADCs. This allows DSP technologies to take the next step in optical communications without requiring complex coherent detection. This is of particular of interest in metropolitan area networks. The full-field receiver investigated requires only an additional asymmetrical Mach-Zehnder interferometer and balanced photodiode to achieve a 50% increase in EDC reach compared to amplitude only detection.

Techniques for engineering quantum states

In this thesis I theoretically study quantum states of ultracold atoms. The majority of the Chapters focus on engineering specific quantum states of single atoms with high fidelity in experimentally realistic systems. In the sixth Chapter, I investigate the stability and dynamics of new multidimensional solitonic states that can be created in inhomogeneous atomic Bose-Einstein condensates. In Chapter three I present two papers in which I demonstrate how the coherent tunnelling by adiabatic passage (CTAP) process can be implemented in an experimentally realistic atom chip system, to coherently transfer the centre-of-mass of a single atom between two spatially distinct magnetic waveguides. In these works I also utilise GPU (Graphics Processing Unit) computing which offers a significant performance increase in the numerical simulation of the Schrödinger equation. In Chapter four I investigate the CTAP process for a linear arrangement of radio frequency traps where the centre-of-mass of both, single atoms and clouds of interacting atoms, can be coherently controlled. In Chapter five I present a theoretical study of adiabatic radio frequency potentials where I use Floquet theory to more accurately model situations where frequencies are close and/or field amplitudes are large. I also show how one can create highly versatile 2D adiabatic radio frequency potentials using multiple radio frequency fields with arbitrary field orientation and demonstrate their utility by simulating the creation of ring vortex solitons. In the sixth Chapter I discuss the stability and dynamics of a family of multidimensional solitonic states created in harmonically confined Bose-Einstein condensates. I demonstrate that these solitonic states have interesting dynamical instabilities, where a continuous collapse and revival of the initial state occurs. Through Bogoliubov analysis, I determine the modes responsible for the observed instabilities of each solitonic state and also extract information related to the time at which instability can be observed.