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Development of Parallel Plate Avalanche Counter for heavy ion collision in radioactive ion beam
Wei, Xianglun,Guan, Fenhai,Yang, Herun,Wang, Yijie,Zhang, Junwei,Ma, Peng,Diao, Xinyue,Lu, Chengui,Li, Meng,Guan, Yuanfan,Duan, Limin,Hu, Rongjiang,Zhang, Xiuling,Xiao, Zhigang Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.3
We have developed a position-sensitive Parallel Plate Avalanche Counter (PPAC) to detect the fission fragments and reconstruct the fission reaction plane in the experiment of studying nuclear equation of state (nEOS) by means of heavy ion collision (HIC). This experiment put forward high requirements for the performances of PPAC, such as the time resolution, efficiency and position resolution. According to these requirements we designed the PPAC with an active area of 240 mm × 280 mm working at low gas pressure. The results show that time resolution could be less than 300 ps. Position resolution is consistent with the theoretical calculation about 1.35 mm. Detection efficiency could be approaching 100% gradually with the voltage increasing in different gas pressures. The performances of PPAC have also been verified in beam experiment. Each set of anode wires can be accurately separated in the position spectrum. In the beam experiment, we also got the back-to-back correlation of fission fragments which is one of the direct signals characterizing binary decay.
The investigation of a new fast timing system based on DRS4 waveform sampling system
Jinda Chen,Chengming Du,Jinda Chen,Herun Yang,Jie kong,Haibo Yang,Peng Ma,Guozhu Shi,limin Duan,Zhengguo Hu 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.2
In the study of nuclear structure, the fast timing technique can be used to measure the lifetime of excitedstates. In the paper, we have developed a new fast timing system, which is made up of two LaBr3:Cedetectors and a set of waveform sampling system. The sampling system based on domino ring samplerversion 4 chip (DRS4) can digitize and store the waveform information of detector signal, with a smallervolume and higher timing accuracy, and the waveform data are performed by means of digital waveformanalysis methods. The coincidence time resolution of the fast timing system for two annihilation 511 keVg photon is 200ps (FWHM), the energy resolution is 3.5%@511 keV, and the energy linear response in thelarge dynamic range is perfect. Meanwhile, to verify the fast timing performance of the system, the152Gd-21þ state form bþ decay of 152Eu source is measured. The measured lifetime is 45.3(±5.0)ps, veryclose to the value of the National Nuclear Data Center (NNDC: 46.2((±3.9)ps). The experimental resultsindicate that the fast timing system is capable of measuring the lifetime of dozens of ps. Therefore, thesystem can be widely used in the research of the fast timing technology.
Measurement of TOF of fast neutrons with <sup>238</sup>U target
Li, Meng,Guan, Yuanfan,Lu, Chengui,Zhang, Junwei,Yuan, Xiaohua,Duan, Limin,Yang, Herun,Hu, Rongjiang,He, Zhiyong,Wei, Xianglun,Ma, Peng,Gan, Zaiguo,Yang, Chunli,Zhang, Hongbin,Chen, Liang,Qiu, Tianli Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6
We developed a Dual-PPACs detector for fast neutron measurements that consists of two sets of PPAC: conventional PPAC and fission PPAC. A<sup>238</sup>U(U<sub>3</sub>O<sub>8</sub>) coating is placed in the fission PPAC's anode, which is used as the neutrons conversion layer. An experiment was performed to measure neutron time-of-flight (TOF) in which <sup>252</sup>Cf spontaneous fission source was used. An excellent time resolution of 164ps has been observed at 6 mbar in isobutene gas. With the excellent time resolution of Dual-PPACs detector, exact neutron energy can be extracted from the timing measurement. The experimental detection efficiency was 1.9 × 10<sup>-7</sup>, consistent with the efficiency of 2.5 × 10<sup>-7</sup> given by a Geant4 simulation. Ultimately, the results show that the Dual-PPACs detector is a suitable candidate for measuring fast neutrons in the future CiADS system.