分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2023-09-14
Liu, Tao
Song, Haisheng
Yu, Yuhong
Yan, Duo
Sun, Zhiyu
Tang, Shuwen
Lu, Fenhua
Wang, Shitao
Zhang, Xueheng
Li, Xianqin
Yang, Haibo
Fang, Fang
Zhang, Yongjie
Ma, Shaobo
Ong, Hooijin
Zhao, Chengxin
摘要： A fully digital data acquisition system based on a field-programmable gate array (FPGA) was developed for a CsI(Tl) array at the External Target Facility (ETF)in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by -rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard and sources. The scheme, which included a moving average filter, baseline restoration, leading-edge discrimination, moving window deconvolution and digital charge comparison was subsequently implemented on the FPGA. A good energy resolution of 5.7% for 1.33 MeV rays and excellent - identification using the digital charge comparison method were achieved, which satisfies CsI(Tl) array performance requirements.
分类： 物理学 >> 核物理学 提交时间： 2023-09-11
Liu, Xiangman
Tang, Shuwen
Wang, Wei
Yu, Yuhong
Sun, Zhiyu
Zhang, Yongjie
Fang, Fang
Yan, Duo
Wang, ShiTao
Zhang, Xueheng
Jin, Shuya
Hu, Bitao
摘要： Gamma-ray polarimetry is a new and prospective tool for studying various extreme high-energy celestial objects and is of great significance for the development of astrophysics. With the rapid development of microsatellite technology, the advantages in space exploration are becoming increasingly apparent. Therefore, in this paper, we conducted a simulation study on a soft gamma-ray polarimeter for a microsatellite in space. Here, we proposed a unique design structure for the polarimeter based on the microsatellite design concept and the Compton scattering principle. And then, the detailed Monte Carlo simulations using mono-energetic gamma-ray linear polarization sources and the Crab-like sources in the energy range of 0.1-10 MeV with full consideration of the orbital background were performed. The simulation results show that the polarimeter can exhibit excellent polarization detection performance. The modulation factor is 0.800.01, and the polarization angles are accurate within an error of 0.2 at 200 keV for on-axis incidence. For the Crab-like sources for on-axis incidence, the polarization degrees are consistent with the set values within the error tolerance, the modulation factor is 0.760.01, and the minimum detectable polarization reaches 2.4% at 3 for an observation time of 106 seconds. In addition, the polarimeter has recoil electron tracking, imaging, and powerful background suppression at a large field of view (2 sr). The polarimeter designed can meet the requirements of a space-soft gamma-ray polarization detector very well and has a bright research prospect.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
WU Fang-Fang
ZHOU Ze-Ran
YANG Yong-Liang
SUN Bao-Gen
ZOU Jun-Yin
LU Ping
CHENG Chao-Cai
LUO Qing
XU Jun
摘要： The four electrodes in the stripline beam position monitor (BPM) for Hefei Light Source (HLS II) storage ring are of axially symmetric type. We have derived a new calibration method of electrode gains for this type stripline BPM. The gain fit error of different data grids was analyzed, and the � 5 mm by � 5 mm grid is the best. The electrode gains of two stripline BPMs (HLS II SR-BD-STLB1 and HLS II SR-BD-STLB2) were obtained based on offline calibrated data. The results show that data after fitting gains are improved, with the electrode gains being between 0.94 and 1.15.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： Based on the statistical characteristics of energy spectrum and the features of spectrum-shifting in spectrometry, the parameter adjustment method of Gaussian function space was applied in the simulation of spectrum-shifting. The transient characteristics of energy spectrum were described by the Gaussian function space, and then the Gaussian function space was transferred by parameter adjustment method. Furthermore, the spectrum-shifting in measurement of energy spectrum was simulated. The applied example shows that the parameters can be adjusted flexibly by this method to meet the various requirements in simulation of energy spectrum-shifting. This method was one parameterized simulation method with good performance for the practical application.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yani Zuo
Shiying Cao
Shaoyang Dai
Yige Lin
Tao Yang
Baike Lin
Fei Meng
Weiliang Chen
Kun Liu
Fasong Zheng
Tianchu Li
Fang Fang
摘要： We report the construction and characterization of a narrow-linewidth laser system to interrogate the E2 clock transitions at 436 nm of ytterbium ions trapped in end-cap traps. The 871 nm seed laser at the fundamental frequency is referenced to a 10 cm long notched ULE cavity. The output of the laser system is delivered to a narrow-linewidth femtosecond fiber comb, which has been referenced to an ultrastable 698 nm laser, with a phase noise-canceled fiber link. The beat between the laser and the comb shows a sub-Hz linewidth, and with a stability better than 2E-15@1~100 s. The performance of the self-developed wavelength extension ports at 871 nm of the narrow linewidth erbium-doped fiber comb with single-point frequency-doubling technique is also verified.
分类： 生物学 >> 生物物理学 >> 神经科学 提交时间： 2016-05-18
Chen, Juan
He, Yingchen
Zhu, Ziyun
Peng, Yujia
Zhang, Xilin
Fang, Fang
Chen, Juan
He, Yingchen
Zhu, Ziyun
Peng, Yujia
Zhang, Xilin
Fang, Fang
Fang, Fang
Fang, Fang
Zhou, Tiangang
摘要： Crowding, the identification difficulty for a target in the presence of nearby flankers, is ubiquitous in spatial vision and is considered a bottleneck of object recognition and visual awareness. Despite its significance, the neural mechanisms of crowding are still unclear. Here, we performed event-related potential and fMRI experiments to measure the cortical interaction between the target and flankers in human subjects. We found that the magnitude of the crowding effect was closely associated with an early suppressive cortical interaction. The cortical suppression was reflected in the earliest event-related potential component (C1), which originated in V1, and in the BOLD signal in V1, but not other higher cortical areas. Intriguingly, spatial attention played a critical role in the manifestation of the suppression. These findings provide direct and converging evidence that attention-dependent V1 suppression contributes to crowding at a very early stage of visual processing.
分类： 生物学 >> 生物物理学 >> 神经科学 提交时间： 2016-05-12
Chen, Nihong
Li, Sheng
Fang, Fang
Chen, Nihong
Li, Sheng
Fang, Fang
Chen, Nihong
Li, Sheng
Fang, Fang
Chen, Nihong
Fang, Fang
Bi, Taiyong
Bi, Taiyong
Zhou, Tiangang
Liu, Zili
摘要： Much has been debated about whether the neural plasticity mediating perceptual learning takes place at the sensory or decision-making stage in the brain. To investigate this, we trained human subjects in a visual motion direction discrimination task. Behavioral performance and BOLD signals were measured before, immediately after, and two weeks after training. Parallel to subjects' long-lasting behavioral improvement, the neural selectivity in V3A and the effective connectivity from V3A to IPS (intraparietal sulcus, a motion decisionmaking area) exhibited a persistent increase for the trained direction. Moreover, the improvement was well explained by a linear combination of the selectivity and connectivity increases. These findings suggest that the long-term neural mechanisms of motion perceptual learning are implemented by sharpening cortical tuning to trained stimuli at the sensory processing stage, as well as by optimizing the connections between sensory and decision-making areas in the brain. (C) 2015 Elsevier Inc. All rights reserved.
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