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The LLRF measurement and analysis of the SSC-linac RFQ
No full textThe manufacturing process of the SSC-LINAC RFQ went to end and the LLRF measurement has been done. To reduce the disturbance from the test environment, a dielectric block has been used as the perturbation body instead of the beads. The error induced by the block and the sampling approach have been investigated. As the results, the frequency of the RFQ is 53.557 MHz without tuning, which is not far from the design value 53.667 MHz. The Q0 value is 4925.8. The unflatness of the field along the beam axis is less than ±4%, which meets the simulation results. The frequency will be adjusted by tuning plungers in operation. In this paper, the measured results of the field distribution along the cavity will be compared with the modulated electrodes simulation.(5 refs
Energy dependence of highly charged ions guided through nanocapillaries in polycarbonate
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The transmission of Xe10+ ions, with incident kinetic energies of 200-500 keV, through polycarbonate capillaries, with a diameter of 150 nm and a length of 30 mu m, has been studied using a one-dimensional position sensitive detector. The transmitted ion yields were measured as a function of the tilt angle. The results are used to evaluate the guiding angle, which is a measure of the guiding power specifying the capability of insulating capillaries to guide ions at equilibrium. Following the semi-empirical scaling law, the potential in the entrance region in this work is nearly an order of magnitude larger than that proposed by low energy data.</span
Slow extraction design of HIMM
No full text<span style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">A heavy ion medical machine (HIMM) is proposed for cancer therapy in Lanzhou, China. The slow extraction design of the synchrotron is introduced in this paper. Eight sextupoles are used; four of them are for correcting the chromaticity and the rest for driving the 3rd-order resonance. In order to save the aperture of vacuum chamber, a 3-magnet bump is adopted during the extraction process. The phase space map in the entrance of the electrostatic septum and the last 3 turns' particle trajectory before particle extraction are given. Copyright © 2013 by JACoW.(4 refs)</span>Asian Committee for Future Accelerators (ACFA); American Physical Society Division of Physics of Beams (APS-DPB); Chinese Academy of Sciences (CAS); European Physical Society Accelerator Group (EPS-A
Key elements of space charge compensation on a low energy high intensity beam injector
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Space charge effect (SCE) along the beam line will decrease beam quality. Space charge compensation (SCC) with extra gas injection is a high-efficiency method to reduce SCE. In this paper, we will report the experimental results on the beam profile, potential distribution, beam emittance, and beam transmission efficiency of a 35 keV/90 mA H+ beam and a 40 keV/10 mA He+ beam compensated by Ar/Kr. The influence of gas type, gas flow, and injection location will be discussed. Emphasis is laid on the consideration of SCC when designing and commissioning a high intensity ion beam injector. Based on measured data, a new definition of space charge compensation degree is proposed. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794966]</span
基于FPGA的容错异步串行收发器装置
No full text<span style="color: rgb(69, 69, 69); font-family: Arial, Helvetica, sans-serif; line-height: 21px; text-indent: 24px;"> 本实用新型提出基于FPGA的容错异步串行收发器。以解决UART的发送器和接收器因受到高能射线的照射而造成的单粒子翻转（SEU）和数据通信中检错和纠错的问题。本实用新型包括有数据发送器，数据接收器，扩展汉明码编码器，扩展汉明码解码器，多数表决器，少数表决器。对所有的模块分别做TMR处理。对于发送器，首先数据处理单元将要发送的数据送入扩展汉明码编码器，编码器将编码后的码字分别送入多数表决器，将多数表决器得到表决后的码字送入串行发送器中，串行发送器将并行数据转换成串行数据发送出去。对于接收器，将串行输入信号通过引脚输入到FPGA中，在FPGA中通过串行接收器实现接收数据的串并转换，串行接收器将串行数据转换成并行数据之后，送入解码器，解码器不仅可以对接收到码字做译码得到正确的信息数据，而且如果在传输过程中，由于信道受到的干扰或发送数据本身发生SEU，解码器可以对错误数据进行检测和纠正，同时得到错误信息。</span
数字脉冲电源同步定时触发系统
No full text<span style="color: rgb(69, 69, 69); font-family: Arial, Helvetica, sans-serif; line-height: 21px; text-indent: 24px;"> 本实用新型涉及用于实现多台数字脉冲电源远程同步定时触发控制的一种数字脉冲电源同步定时触发系统。其特点在于包括与控制计算机互联的以现场可编程门阵列FPGA为硬件的触发源服务器，触发源服务器与一级扇出器相连，一级扇出器分别与多路无时间差的二级扇出器对应相连，二级扇出器与数字脉冲电源模块相连。该系统能实现离子加速器数字脉冲电源或相关工业领域多台数字脉冲电源按照设定的时间序列同步启动或者分组定时同步启动控制，满足了相关领域数字脉冲电源在远程控制方式下灵活定时同步启动的要求。</span
Swift heavy ion irradiation acts as a size filter to Ag nanoparticles embedded in silica glass
No full textThe swift heavy ion (SHI) irradiation using as a tool for the ion-beam-shaping technique has attracted much attention in recently years, which can transform spherical metal nanoparticles (Nps) to prolate spheroids, nanorods or nanowires, with the elongation along the beam direction. In the present paper, we show that SHI irradiation can also act as a size filter to Ag Nps embedded in silica glass. In experiment, Ag Nps were introduced into silica glass by Ag ion implantation. Subsequently, 73 MeV Ca ions were used to irradiate the samples contained Ag Nps to different fluences. The direction of incident ions is perpendicular to sample surface. The surface plasmon resonance (SPR) absorbance peak of Ag Nps shifts to short wavelength with increase of irradiation fluence, meanwhile, the full width at half maximum (FWHM) of SPR peak decreases with increase of irradiation fluence. The decrease of FWHM indicates the reduction of Ag Nps size dispersion. TEM results show that Ag Nps smaller than 2.0 nm dissolve during irradiation, only Ag Nps larger than 2.0 nm survive and distribute in a narrow region. High energy Ca ion irradiation seems to act as a size filter. From TEM micrographs the size dispersion of Ag Nps is reduced comparing with that before irradiation, which is consistent with optical results. (C) 2013 Elsevier B.V. All rights reserved
Effects of irradiation of 290 MeV U-ions in GaN epi-layers
No full textIn the present work, the resistivity, mobility and the carrier density at either room temperature or 77 K in 3-mu m-thick n-GaN epi-layers irradiated with 290 MeV U-238(32+) ions were tested with Hall measurements. It is found that the carrier mobility at 77 K is lower than that at room temperature in the specimens irradiated to fluences of the 1 x 10(9) and 1 x 10(19) ions/cm(2), showing a behavior different from the pristine specimen. The carrier density increases with ion fluence, and is above the dopant concentration when the ion fluence reaches 5 x 10(19) ions/cm(2). Moreover, the ionized impurity scattering plays a dominant role in the Hall effect after irradiation. A decrease of the ionized impurities due to the recombination of Ga vacancies (V-Ga(-3)) and the Ga interstitials (Ga(l)) was observed. The irradiation to the fluence of 5 x 10(10) ions/cm(2) produced N vacancies, which act as a kind of donor making the carrier density increase. The Raman spectra show that the E-2 (high) mode shifts to a higher frequency meanwhile the FWTH increases after the irradiation, indicating there is an increase of strain in the irradiated GaN epi-layers. A consistency between the Raman spectra and the HRXRD spectra was found. (C) 2013 Elsevier B.V. All rights reserved
High Intensity heavy ion Accelerator Facility (HIAF) in China
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">HIAF (High Intensity heavy ion Accelerator Facility), a new facility planned in China for heavy ion related researches, consists of two ion sources, a high intensity Heavy Ion Superconducting Linac (HISCL), a 45 Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage ring system. The key features of HIAF are unprecedented high pulse beam intensity and versatile operation mode. The HIAF project aims to expand nuclear and related researches into presently unreachable region and give scientists possibilities to conduct cutting-edge researches in these fields. The general description of the facility is given in this article with a focus on the accelerator design. (C) 2013 Elsevier B.V. All rights reserved.</span