A thorough detector response calibration using radioactive sources is necessary for the Jiangmen Underground Neutrino Observatory. Herein, we discuss the design of a source positioning system based on ultrasonic techn...A thorough detector response calibration using radioactive sources is necessary for the Jiangmen Underground Neutrino Observatory. Herein, we discuss the design of a source positioning system based on ultrasonic technology, aiming for a 3-cm precision over the entire35-m diameter detector sphere. A prototype system is constructed and demonstrated for the experiment.展开更多
The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although...The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although the tests were successful,this method was finally discarded and eventually nearly forgotten.Currently,this approach is not considered for large LXe dark matter detectors.Instead,the dual-phase technology was selected despite many limitations and challenges.In two independent studies,two groups from Columbia University and Shanghai Jiao Tong University reevaluated proportional scintillation in the liquid phase.Both studies established the merits for very large LXe detectors,but the Columbia group also encountered apparent limitations,namely the shadowing of the light by the anode wires,and a dependence of the pulse shape on the drift path of the electrons in the anode region.The differences between the two studies,however,are not intrinsic to the technique,but a direct consequence of the chosen geometry.Taking the geometrical differences into account,the results match without ambiguity.They also agree with the original results from the Waseda group.展开更多
To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The r...To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The radioactivity of the proposed hydrophone is strictly controlled by selecting pure raw materials, especially active piezoelectric ceramics. The electroacoustic performance of the hydrophone is improved by making structural optimization. High sensitivity and aimed directivity are achieved using 33-mode piezoelectric ceramic rings arranged in series and improvement in the radiating head of the Tonpilz hydrophone, respectively. All electroacoustic performances are studied through finite element analyses.The simulations indicate that the electroacoustic performances of the hydrophones in linear alkylbenzene-based liquid scintillator can be approximately predicted according to the results in water because their differences caused by two types of acoustic media, water and liquid scintillator, are known. The tests show that the hydrophone prototype can achieve a maximum sensitivity of-209.3dB and a beamwidth of 132.2° at a frequency of 143 kHz.In addition, eight hydrophones only contributed to a background radioactivity level of 26 ± 4 mHz in the neutrino analysis.展开更多
基金supported by the ‘‘Strategic Priority Research Program’’ of the Chinese Academy of Sciences(No.XDA10010800)the ‘‘Fundamental Research Funds for the Central Universities’’(No.3102017zy010)
文摘A thorough detector response calibration using radioactive sources is necessary for the Jiangmen Underground Neutrino Observatory. Herein, we discuss the design of a source positioning system based on ultrasonic technology, aiming for a 3-cm precision over the entire35-m diameter detector sphere. A prototype system is constructed and demonstrated for the experiment.
基金supported by a Grant from the Ministry of Science and Technology of China(No.2016YFA0400301)。
文摘The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although the tests were successful,this method was finally discarded and eventually nearly forgotten.Currently,this approach is not considered for large LXe dark matter detectors.Instead,the dual-phase technology was selected despite many limitations and challenges.In two independent studies,two groups from Columbia University and Shanghai Jiao Tong University reevaluated proportional scintillation in the liquid phase.Both studies established the merits for very large LXe detectors,but the Columbia group also encountered apparent limitations,namely the shadowing of the light by the anode wires,and a dependence of the pulse shape on the drift path of the electrons in the anode region.The differences between the two studies,however,are not intrinsic to the technique,but a direct consequence of the chosen geometry.Taking the geometrical differences into account,the results match without ambiguity.They also agree with the original results from the Waseda group.
基金supported by the“trategic Priority Research Program”of the Chinese Academy of Sciences(No.XDA10010800)the National Natural Science Foundation of China(No.12074318)。
文摘To satisfy the accurate positioning requirement of the calibration source in the Jiangmen Underground Neutrino Observatory, a Tonpilz-type hydrophone with low radioactivity and high electroacoustics is developed.The radioactivity of the proposed hydrophone is strictly controlled by selecting pure raw materials, especially active piezoelectric ceramics. The electroacoustic performance of the hydrophone is improved by making structural optimization. High sensitivity and aimed directivity are achieved using 33-mode piezoelectric ceramic rings arranged in series and improvement in the radiating head of the Tonpilz hydrophone, respectively. All electroacoustic performances are studied through finite element analyses.The simulations indicate that the electroacoustic performances of the hydrophones in linear alkylbenzene-based liquid scintillator can be approximately predicted according to the results in water because their differences caused by two types of acoustic media, water and liquid scintillator, are known. The tests show that the hydrophone prototype can achieve a maximum sensitivity of-209.3dB and a beamwidth of 132.2° at a frequency of 143 kHz.In addition, eight hydrophones only contributed to a background radioactivity level of 26 ± 4 mHz in the neutrino analysis.
