Cavity beam position monitor (BPM) is widely used in a precise electron beam position measurement. Based on high performance oscilloscope-embedded EPICS input/output controller, we developed an on-line cavity BPM signal processing system for fast data acquisition solution when designing a cavity BPM. Also, methods for extracting the position information from cavity pickup signals and calibration algorithm are included in this solution.
Vol.22, No.6
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808
SYNCHROTRON SCIENCE AND TECHNOLOGY
Research article 20 Dec 2011
Yong-Bin Leng，ZHANG Ning，WANG Baopeng
keyword：Cavity；Embedded input/output controller；On-line acquisition；Signal processing；Fast Fourier transform；
Research article 20 Dec 2011
ZHANG Haiou，DAI Dongdong，TANG Ziyi，ZHANG Jidong，SHAO Bin，HE Suixia
Some metal compounds called as Non-Evaporable-Getter have been widely used to improve vacuum system performance of accelerator facility. In this paper, a TiZrV film on the surface of stainless steel vacuum pipe is made by direct current magnetron sputtering, and its vacuum performance is experimentally studied. Our results show that the TiZrV film is partly activated at 160°C, and its pressure performance is similar with one at higher temperature. The coating reduces the ultimate pressure and prominently shortens the pressure-down time in a sputter ion pump system, thus creating evenly distributed pressure profile in a coating pipe. The adsorption rate is steady, and adsorption amount increases linearly. Such TiZrV-coated pipe behaves like pump other than gas source in vacuum system.
keyword：Adsorption；Activation；TiZrV；Pressure；Direct current magnetron sputtering；
LOW ENERGY ACCELERATORS AND RADIATION APPLICATIONS
Research article 20 Dec 2011
WANG Yi，CHEN Huangshan，DING Weicheng，QIU Xuezhong，WANG Jingbo，ZHU Xianglei，CHENG Jianping，LI Yuanjing
Long-strip multi-gap resistive plate chamber (LMRPC) were built with (Module 1) or without (Module 2) adhesive tapes and silicones. Their performances were investigated by working gas mixtures of different gradient contents (Test 1: 94% freon, 5% iso-butane and 1% SF6; Test 2: 90% freon, 5% iso-butane and 5% SF6). Both the modules achieved 100% efficiency, with time resolutions of 75 and 70 ps. Comparatively, the Module 1 works with a lower applied HV at the higher noise level, and time resolution was not influenced greatly by the adhesive tapes and silicones.
keyword：Time of flight；Resistive Plate Chamber；Tape；Silicone；Glue；Performance；Noise；
Research article 20 Dec 2011
ZHANG Wei，ZHANG Dongsheng，MA Liqiang，WANG Xufeng，FAN Gangwei
For environment protection in mining areas in northwest China, we developed a CTSRM (comprehensive test system by radon measurement) to measure radon radioactivity and detect dynamic evolution characteristics of mining-induced fractures in overlying strata. It was used to simulate the relationship between the dynamic evolution characteristics and radon concentrations of 33201# coalface at Bulianta coal mine in Inner Mongolia, and feasibility of the method was validate.
keyword：Radon detection；Comprehensive test system；Mining-induced fractures；Physical simulation；
RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE
Research article 20 Dec 2011
QI Yujin，ZHANG Xuezhu
This study was aimed at developing an efficient simulation technique with an ordinary PC. The work involved derivation of mathematical operators, analytic phantom generations, and effective analytical projectors developing for cone-beam CT and pinhole SPECT imaging. The computer simulations based on the analytical projectors were developed by ray-tracing method for cone-beam CT and voxel-driven method for pinhole SPECT of degrading blurring. The 3D Shepp–Logan, Jaszczak and Defrise phantoms were used for simulation evaluations and image reconstructions. The reconstructed phantom images were of good accuracy with the phantoms. The results showed that the analytical simulation technique is an efficient tool for studying cone-beam CT and pinhole SPECT imaging.
keyword：Pinhole SPECT；Computer simulation；Mathematical Phantom；Cone-beam CT；
Research article 20 Dec 2011
Tian-Yu Ma，DAI Tiantian，LIU Hui，CUI Junjian，WEI Qingyang，LIU Yaqiang，WANG Shi
An SPECT system dedicated to small animal imaging shall be of a millimeter spatial resolution or even better. This study was aimed at achieving 0.5-mm spatial resolution for a small animal SPECT system at low cost. It was developed from a single-head clinical SPECT scanner, with a seven-pinhole collimator and a four-degree-of- freedom motion control stage. Several key techniques were developed, including high-resolution image reconstruction algorithm, high accuracy geometrical calibration method, and optimized system matrix derivation scheme. The system matrix was derived from Monte-Carlo simulation and de-noised by fitting each point spread function to a two dimensional Gaussian function. Experiments of point source and ultra micro hot rod phantom were conducted. With a spatial resolution of 0.5–0.6 mm, this system provides a practical way for low-cost high-resolution animal imaging on a clinic SPECT system.
keyword：Image reconstruction；SPECT；High resolution；Multi-pinhole collimator；System matrix；
Research article 20 Dec 2011
WU Zhangwen，GOU Chengjun，LI Xia，HOU Qing
Hybrid pencil beam model (HPBM) offers an efficient approach to calculate the three-dimension dose distribution from a clinical electron beam. Still, clinical radiation treatment activity desires faster treatment plan process. Our work presented the fast implementation of HPBM-based electron dose calculation using graphics processing unit (GPU). The HPBM algorithm was implemented in compute unified device architecture running on the GPU, and C running on the CPU, respectively. Several tests with various sizes of the field, beamlet and voxel were used to evaluate our implementation. On an NVIDIA GeForce GTX470 GPU card, we achieved speedup factors of 2.18 – 98.23 with acceptable accuracy, compared with the results from a Pentium E5500 2.80 GHz Dual-core CPU.
keyword：GPU；HPBM；Dose calculation；
NUCLEAR ELECTRONICS AND INSTRUMENTATION
Research article 20 Dec 2011
Qi An，CAO Zhe，LIU Shubin，LI Cheng
In this paper, we report a clock distribution system for Water Cherenkov Detector Arrays (WCDAs) in Large High Altitude Air Shower Observatory (LHAASO) project. The designed electronics system is of high performance in implementing the clock distribution among detectors of a large scale of dimension. Based on Serializer/Deserializer (SerDes) and fiber transmission, the clock distribution system is the modules of central back end to distributed front end. The clock distribution system has been evaluated with a two modules system. While all the four SerDes candidates for clock transmission with jitters below 17 ps, the DS92LV16 has a fixed phase relationship between transmission clock and recovered clock, hence its use in LHAASO WCDAs.
keyword：LHAASO；Clock distribution；Distributed architecture；Serializer/Deserializer；
Research article 20 Dec 2011
LI Xiangyu，LIU Haifeng，ZHANG Qi，SUN Yihe
Integrated circuits of deep submicron (DSM) CMOS technology are advantageous in volume density, power consumption and thermal noise for multichannel particle detection systems, but there are challenges in the front-end circuit design. In this paper, we present a 0.18 μm CMOS front-end readout circuit for low noise CdZnTe detectors in tens of pF capacitance. Solutions to the noise and gate leak problems in DSM technologies are discussed in detail. A prototype chip was designed, with a charge sensitive preamplifier, a 4th order semi-Gaussian shaper and several output drivers. Test results show that the chip has an equivalent noise charge of 164 e, without connecting it to a detector, with an integral nonlinearity of <0.21% and differential nonlinearity of < 3.75%.
keyword：Low noise；Readout circuit；ASIC；Particle detector；Deep submicron；
Research article 20 Dec 2011
Ke-Zhu Song，CAO Ping，YANG Junfeng
Some specified chips in traditional Manchester-II encoding/decoding designs are used to guarantee strictly the stability of the input wave, otherwise the capacity of anti-interference and resilience are degraded seriously. In this paper, a new Manchester-II encoding/ decoding system is used for nuclear logging by a 7 000 m armoring cable. A thorough hardware wave tracking decoding algorithm is proposed and realized in a FPGA hardware chip. An on-site measurements show that this transmission system can decode correctly in real time, with a bit error rate of better than 10–10.
keyword：Long distance transmission；Hardware real time decoding algorithm；Nuclear logging；Armoring cable；Manchester II code；
Research article 20 Dec 2011
Lei Zhao，ZHOU Jiawen，LIU Shubin，YIN Chunyan，AN Qi
A high resolution time measurement system with high data transfer rate was designed for the COLTRIMS (Cold Target Recoil-Ion Momentum Spectroscopy) system in Institute of Modern Physics, Chinese Academy of Sciences. It is used to measure the Time of Flight (TOF) with a high resolution for all 20 channels. Based on the PCI Extensions for Instrumentation (PXI) standard, the readout electronics system consists of one Clock-Trigger fan-out module and four TOF modules. Test results show that the system meets the demands of COLTRIMS, with a time resolution of better than 25 ps and a data transfer rate over 20 MB/s.
keyword：PXI；Time of flight；Burst transfer；
