[en] In order to meet the needs of tune measurement at HLS II, a tune measurement system based on Zynq SOC has been developed. The system mainly consists of front-end electronics, FPGA, ARM and PC, which is low-cost, compact, and has rich-feature and adapts to different machine research experiments. The FPGA (PL) can provide two kinds of signals for exciting the beam: parametric frequency sweep signal and bandwidth limited white noise signal. The FFT algorithms and calculation of tune are running in the ARM (PS). The experiments on HLS II storage ring show that the tune measuring accuracy has reached 0.0006/0.0001 based on sweep frequency excitation and 0.0007/0.0036 based on bandwidth limited white noise excitation. In the future, the system could measure other parameters like chromaticity et al. (authors)

[en] In this paper, the algorithm for calibrating radionuclide activity of waste barrels from a nuclear power plant is studied. A simulations to validate the algorithm was done on a model of 1:2 ratio to an actual waste barrel at a nuclear power plant. The results indicate that the image reconstruction errors are smaller than other algorithms. Further more, this method, with strong practicability, can well meet the requirements of TGS device. (authors)

[en] In this paper, the turn-by-turn system of Hefei Light Source (HLS), and the log-ratio electronics circuit with working frequency 408MHz (2*RF of HLS) are described. They are used to monitor the injection effectiveness, damping rate, β oscillation and υ variation for research the instability of beam. The Log-ratio signal processor has low noise, high bandwidth and wide dynamic range, as well as linear response. The calibration of the system and its application in commissioning of the upgraded injection system of HLS is emphases. The practice proves the turn-by-turn BPM system is quite useful for the beam-injection adjusting and indispensable for machine research

[en] Multi-energy method to rectify the linear attenuation coefficients in transmitted image reconstruction by tomographic gamma ray scanning was preliminarily explored. The gamma ray linear attenuation coefficients for different energies were calculated using Monte Carlo method for 18 different kinds of materials. The relationship between ray linear attenuation coefficient and energy was fitted for given material and density, so as to reconstruct transmitted image for different energies. (authors)

[en] A logarithm processing algorithm to measure beam transverse size and position is proposed and preliminary experimental results in Hefei Light Source II(HLS II) are given. The algorithm is based on only 4 successive channels of 16 anode channels of multianode photomultiplier tube(MAPMT) R5900U-00-L16, which has typical rise time of 0.6 ns and effective area of 0.8 × 16 mm for a single anode channel. In the paper, we first elaborate the simulation results of the algorithm with and without channel inconsistency. Then we calibrate the channel inconsistency and verify the algorithm using a general current signal processor Libera Photon in a low-speed scheme. Finally we get turn-by-turn beam size and position and calculate the vertical tune in a high-speed scheme. The experimental results show that measured values fit well with simulation results after channel differences are calibrated, and the fractional part of the tune in vertical direction is 0.3628, which is very close to the nominal value 0.3621. (authors)

[en] In order to improve the accumulation of the injected beam, it is necessary to restrain β-oscillation because of injection system error. This paper systematically introduces the design principle and circuit of the feedback system for the injected β-oscillation suppression of HLS. It also provides the preliminary experimental results. As the proof of the theory and pre-study, authors use a relatively simple analog filter and phase shifter to agitate the Kicker course, which causes the β-oscillation, and get the feedback, from which authors see the obvious suppression effect. All of these are the foundation of feedback system of bunch-by-bunch and lower frequency in the future, which are for the research of transverse beam and longitudinal beam instability

[en] During the past year, several measures have been tried to improve the stability of injected beam at HLS (Hefei Light Source), which has newly upgraded its injection system. To overcome the evident residual betatron oscillation, one specific betatron-oscillation suppressor circuitry is accomplished to take it under control. Means to excite and damp beam motions has been suggested, as well as a PLL circuit in plan to track the variation of tune under various machine states. In addition, works as improving the performance of early version of turn-by-turn system and rebuilding the software kit to make it a reliable instrumentation for beam nonlinear dynamics study and machine state monitoring

[en] This paper presents a newly implemented wideband (100 MHz) bunch oscillation measurement system, which is in nature different from the narrow-band (<5 MHz) facilities employed before. Basic formalism and implementation details of the system are introduced to illustrate the function of observing coupled bunch instabilities in time and frequency domain. The designed function includes detecting of transverse oscillation, synchrotron phase oscillation, as well as bunch filling pattern. Some diagnostics results of machine instabilities and application of this system are also discussed, which well depict bunch filling mechanism, instability coupling between transverse and longitudinal directions, inherent machine damping time, as well as dominant oscillation modes. (authors)

[en] FELiChEM is a new experimental facility under construction at the University of Science and Technology of China (USTC). Its core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 2.5-200 μm. It will be a dedicated infrared light source aiming at energy chemistry research. We present the brief design of the FEL oscillators, with the emphasis put on the middle-infrared oscillator. Most of the basic parameters are determined and the anticipated performance of the output radiation is given. The first light of FELiChEM is targeted for the end of 2017. (authors)

[en] During beam injection in Hefei Light Source (HLS), the amplitude of betatron oscillation varies rapidly, and the frequency varies greatly. It is a typical non-stationary process. Using the traditional method to process the time series signal acquired by the bunch-by-bunch measurement system may result in amplitude distortion and phase deviation. Wavelet analysis provides multi-resolution representations of the bunch signal. Subsequently, the oscillation component and baseline drift component can be separated. The locations on timeline and the linear relationships of the components remain the same as the original signal. Compared with the traditional method, the data processing method based on wavelet analysis is capable of analyzing a non-stationary signal and de-noising a signal without appreciable degradation. If will not bring about conspicuous amplitude distortion and phase deviation, and ensures that the subsequent tracking of the evolution of oscillation amplitude, phase, frequency and mode in the time domain is more reliable. Furthermore, the method has been successfully used to extract the amplitude envelope of betatron oscillation and to calculate growth rate and damping rate. It provides an accurate foundation for machine studies, beam diagnosis and the commissioning of bunch-by-bunch feedback system. (authors)