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Identification of anomalous fast bulk events in a p-type point-contact germanium detector

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Nuclear Science and Techniques 2022年第5期33卷 53-67页

作者： Ren-Ming-Jie Li Shu-Kui Liu shin-ted lin Li-Tao Yang Qian Yue Chang-Hao Fang Hai-Tao Jia Xi Jiang Qian-Yun Li Yu Liu Yu-Lu Yan Kang-Kang Zhao Lei Zhang Chang-Jian Tang Hao-Yang Xing Jing-Jun Zhu College of Physics Sichuan UniversityChengdu 610065China Key Laboratory of Particle and Radiation Imaging(Ministry of Education)and Department of Engineering Physics Tsinghua UniversityBeijing 100084China

The ultralow detection threshold,ultralow intrinsic background,and excellent energy resolution of ptype point-contact germanium detectors are important for rare-event searches,in particular for the detection of direct dark matter interactions,coherent elastic neutrino-nucleus scattering,and neutrinoless double beta *** bulk events with an extremely fast rise time are observed in the CDEX-1B *** report a method of extracting fast bulk events from bulk events using a pulse shape simulation and reconstructed source experiment *** data and the distribution of X-rays generated by intrinsic radioactivity verified that the fast bulk experienced a single hit near the passivation *** performance of this germanium detector indicates that it is capable of single-hit bulk spatial resolution and thus provides a background removal technique.

关键词： p-type point-contact germanium detector Dark matter Pulse shape analysis Anomalous fast bulk events

Cryogenic phonon-detector model with solid argon for detecting dark matter

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Chinese Physics C 2023年第12期47卷 1-9页

作者：刘钰张磊鄢雨璐林兴德刘书魁朱敬军唐昌建幸浩洋 College of Physics Sichuan UniversityChengdu 610065China Institute of Nuclear Science and Technology Sichuan UniversityChengdu 610065China

Over the past few years,phonon detectors have emerged as a prevailing technology for detecting lowmass dark matter due to their low thresholds and high *** detectors,which employ either dual-phase detectors combining phonon-light or phonon-electron interactions,have significantly advanced direct dark matter detection ***,as a low-background and high-reserve detection medium,has also played a crucial role in this *** liquid-argon single-phase detectors and gas-liquid two-phase time projection chambers(TPCs)have contributed substantially to the direct detection of high-mass dark *** integrating these distinct detector types,the upper limits of the corresponding mass cross-section in dark matter detection can be *** propose a phonon detector utilizing solid argon as the absorber,which combines the advantages of both aforementioned detector ***,due to the requirement for an ultra-low temperature environment in the tens of millikelvin(mK)range,experimental investigations of solid argon phonon detector performance are currently constrained by technical ***,the performance analysis of the solid argon phonon detector presented in this study is only based on sapphire phonon *** there may be discrepancies between this approximation and the actual performance,the intrinsic characteristics of phonon detectors permit a qualitative evaluation of the solid argon phonon detector's potential capabilities.

关键词： solid argon photon detector cryogenic detector WIMPs

High‑accuracy measurement of Compton scattering in germanium for dark matter searches

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Nuclear Science and Techniques 2022年第12期33卷 75-87页

作者： Hai‑Tao Jia shin‑ted lin Shu‑Kui Liu Hsin‑Chang Chi Muhammed Deniz Chang‑Hao Fang Peng Gu Xi Jiang Yi‑Ke Shu Qian‑Yun Li Yu Liu Ren‑Ming‑Jie Li Chen‑Kai Qiao Chang‑Jian Tang Henry Tsz‑King Wong Hao‑Yang Xing Li‑Tao Yang Qian Yue Yu‑Lu Yan Kang‑Kang Zhao Jing‑Jun Zhu College of Physics Sichuan University610065 ChengduChina Department of Physics National Dong Hwa University97401 ShoufengHualienChina Department of Physics Dokuz Eylül University35160 BucaİzmirTurkey Institute of Physics Academia Sinica11529 TaipeiChina Key Laboratory of Particle and Radiation Imaging(Ministry of Education)and Department of Engineering Physics Tsinghua University100084 BeijingChina Institute of Nuclear Science and Technology Sichuan University610065 ChengduChina

Compton scattering with bound electrons contributes to a significant atomic effect in low-momentum transfer,yielding background structures in direct light dark matter searches as well as low-energy rare event *** report the measurement of Compton scattering in low-momentum transfer by implementing a 10-g germanium detector bombarded by a^(137)Cs source with a radioactivity of 8.7 mCi and a scatter photon captured by a cylindrical NaI(Tl)detector.A fully relativistic impulse approximation combined with multi-configuration Dirac–Fock wavefunctions was evaluated,and the scattering function of Geant4 software was replaced by our calculation *** measurements show that the Livermore model with the modified scattering function in Geant4 is in good agreement with the experimental *** is also revealed that atomic many-body effects significantly influence Compton scattering for low-momentum transfer(sub-keV energy transfer).

关键词： Compton scattering experiment Germanium detector Atomic many-body effects Geant4 Dark matter

Channel pruning on frequency response

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Science China(Information Sciences) 2025年第1期68卷 159-170页

作者： Hang lin Yifan PENG lin BIE Chenggang YAN Xibin ZHAO Yue GAO School of Software Tsinghua University School of Automation Hangzhou Dianzi University

Network pruning has a significant role in reducing network parameters and accelerating the inference time of the network. Some existing methods prune the network based on the frequency of the data, and finally obtain a sub-network with high accuracy. However, according to our experimental analysis, different frequencies of information in the data contribute differently to the accuracy of the model, and using this information directly for pruning without making a selection will lead to incorrect results. We believe that pruning should retain the convolutional kernels in the network that process important information, while those kernels that process unimportant information should be removed. In this paper, we first investigate the meaning of each frequency band information in the spectrum and their contribution to the prediction accuracy of the network,and according to these results, we propose a new pruning method based on frequency response(PFR). Our PFR finds and removes the convolutional kernels in the network that specialize in processing unimportant information, resulting in a compact neural network model. PFR obtains significant experimental results on different datasets, for example, a 56.0% raduction of float points operations(FLOPs) on Res Net-50 and only 0.37% of Top-1 accuracy degradation on the Image Net dataset.

关键词： deep learning model compression filter pruning channel pruning frequency response

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New progresses of fine-grained sediment gravity-flow deposits and their importance for unconventional shale oil and gas plays

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Petroleum Science 2025年第1期22卷 1-15页

作者： Tian Yang Ying-lin Liu State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology) Institute of Sedimentary Geology Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources Chengdu University of Technology

Fine-grained sediments are widely distributed and constitute the most abundant component in sedimentary systems, thus the research on their genesis and distribution is of great significance. In recent years, fine-grained sediment gravity-flows(FGSGF) have been recognized as an important transportation and depositional mechanism for accumulating thick successions of fine-grained sediments. Through a comprehensive review and synthesis of global research on FGSGF deposition, the characteristics,depositional mechanisms, and distribution patterns of fine-grained sediment gravity-flow deposits(FGSGFD) are discussed, and future research prospects are clarified. In addition to the traditionally recognized low-density turbidity current and muddy debris flow, wave-enhanced gravity flow, lowdensity muddy hyperpycnal flow, and hypopycnal plumes can all form widely distributed FGSGFD. At the same time, the evolution of FGSGF during transportation can result in transitional and hybrid gravityflow deposits. The combination of multiple triggering mechanisms promotes the widespread development of FGSGFD, without temporal and spatial limitations. Different types and concentrations of clay minerals, organic matters, and organo-clay complexes are the keys to controlling the flow transformation of FGSGF from low-concentration turbidity currents to high-concentration muddy debris flows. Further study is needed on the interaction mechanism of FGSGF caused by different initiations, the evolution of FGSGF with the effect of organic-inorganic synergy, and the controlling factors of the distribution patterns of FGSGFD. The study of FGSGFD can shed some new light on the formation of widely developed thin-bedded siltstones within shales. At the same time, these insights may broaden the exploration scope of shale oil and gas, which have important geological significances for unconventional shale oil and gas.

关键词： Fine-grained sediment gravity-flow Depositional mechanism Transportation and evolution Distribution pattern Shale oil and gas

In-situ formation of a new cation renders perovskite solar modules with a record efficiency and long-term stability

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Science China Chemistry 2025年第2期68卷 409-410页

作者： Shanxiao lin Xixing Wen Xiuwen Xu College of Electronic and Optical Engineering and College of Flexible Electronics(Future Technology) Nanjing University of Posts and TelecommunicationsNanjing 210023China

Over the past 14 years,the efficiency of perovskite solar cells has surged from 3.8% to 26.7%[1],establishing it as an unrivaled choice for next-generation ***,maintaining the long-term stability of perovskite solar modules(PSMs)remains a *** particular,the thermal-and light-induced changes in crystal structure,composition,and optoelectronic properties are the primary causes of device degradation,currently considered the Achilles’heel that hinders its commercialization[2–4].Now,writing in Science,Ding et al.[5]achieve a milestone by overcoming the thermal-and light-induced degradation,rendering the PSM with a record efficiency of 23.2% and a T80(time to 20% efficiency loss)over 4,000 h at 85℃ and 85%relative humidity(RH)under light *** key behind this milestone is to utilize the cation reactivity to in-situ form methyl tetrahydrotriazinium([MTTZ]+,a new cation)and dimethylammonium([DMA]+)in precursor solution(Figure 1a).These cations remarkably modulate perovskite crystallization and stabilize the perovskite.

关键词： perovskite stability modules

Upper Bounds on the Multicolor Ramsey Numbers r_(k)(C_(4))

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Acta Mathematicae Applicatae Sinica 2025年第1期41卷 286-294页

作者： Tian-yu LI Qi-zhong lin Center for Discrete Mathematics Fuzhou UniversityFuzhou 350108China

The multicolor Ramsey number r_(k)(C_(4))is the smallest integer N such that any k-edge coloring of KN contains a monochromatic C_(4).The current best upper bound of r_(k)(C_(4))was obtained by Chung(1974)and independently by Irving(1974),i.e.,r_(k)(C_(4))≤k^(2)+k+1 for all k≥*** is no progress on the upper bound since *** this paper,we improve the upper bound of r_(k)(C_(4))by showing that r_(k)(C_(4))≤k^(2)+k-1 for even k≥*** improvement is based on the upper bound of the Turan number ex(n,C4),in which we mainly use the double counting method and many novel ideas from Firke,Kosek,Nash,and Williford[***,Ser.B 103(2013),327-336].

关键词： Multicolor Ramsey number Turan number 4-cycle

The profound review of Fenton process:What’s the next step?

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Journal of Environmental Sciences 2025年第1期147卷 114-130页

作者： Yimin lin Junlian Qiao Yuankui Sun Hongyu Dong State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science and EngineeringTongji UniversityShanghai 200092China Department of Environmental Science School of Ecological and Environmental SciencesEast China Normal UniversityShanghai 200241China

Fenton and Fenton-like processes,which could produce highly reactive species to degrade organic contaminants,have been widely used in the field of wastewater ***,the chemistry of Fenton process including the nature of active oxidants,the complicated reactions involved,and the behind reason for its strongly pH-dependent performance,is the basis for the application of Fenton and Fenton-like processes in wastewater ***,the conflicting views still exist about the mechanism of the Fenton *** instance,reaching a unanimous consensus on the nature of active oxidants(hydroxyl radical or tetravalent iron)in this process remains *** review comprehensively examined the mechanism of the Fenton process including the debate on the nature of active oxidants,reactions involved in the Fenton process,and the behind reason for the pH-dependent degradation of contaminants in the Fenton ***,we summarized several strategies that promote the Fe(Ⅱ)/Fe(Ⅲ)cycle,reduce the competitive consumption of active oxidants by side reactions,and replace the Fenton reagent,thus improving the performance of the Fenton ***,advances for the future were proposed including the demand for the high-accuracy identification of active oxidants and taking advantages of the characteristic of target contaminants during the degradation of contaminants by the Fenton process.

关键词： Advanced oxidation process Fenton Hydroxyl radical Fe(IV) Wastewater treatment

Profiles,exposure assessment and expanded screening of PAHs and their derivatives in one petroleum refinery facility of China

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Journal of Environmental Sciences 2025年第1期147卷 550-560页

作者： Ning Wang Fengjiao Jiang lin Xu Yaqi Cai School of Municipal and Environmental Engineering Shandong Jianzhu UniversityJinan 250101China Resource and Environmental Innovation Institute Shandong Jianzhu UniversityJinan 250101China State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China School of Environment Hangzhou Institute for Advanced StudyUCASHangzhou 330106China Hubei Key Laboratory of Environmental and Health Effects of Persistence Toxic Substances Institute of Environment and HealthJianghan UniversityWuhan 430056China

This study investigated environmental distribution and human exposure of polycyclic aromatic hydrocarbons(PAHs)and their derivatives in one Chinese petroleum refinery *** was found that,following with high concentrations of 16 EPA PAHs(∑Parent-PAHs)in smelting subarea of studied petroleum refinery facility,total derivatives of PAHs[named as XPAHs,including nitro PAHs(NPAHs),chlorinated PAHs(Cl-PAHs),and brominated PAHs(Br-PAHs)]in gas(mean=1.57×10^(4)ng/m^(3)),total suspended particulate(TSP)(mean=4.33×10^(3) ng/m^(3))and soil(mean=4.37×10^(3) ng/g)in this subarea had 1.76-6.19 times higher levels than those from other subareas of this facility,surrounding residential areas and reference areas,indicating that petroleum refining processes would lead apparent derivation of ***,compared with those in residential and reference areas,gas samples in the petrochemical areas had higher∑NPAH/∑PAHs(mean=2.18),but lower∑Cl-PAH/∑PAHs(mean=1.43×10^(-1))and∑Br-PAH/∑PAHs ratios(mean=7.49×10^(-2)),indicating the richer nitrification of PAHs than chlorination during petrochemical *** occupational exposure to PAHs and XPAHs in this petroleum refinery facility were 24-343 times higher than non-occupational exposure,and the ILCR(1.04×10^(-4))for petrochemical workers was considered to be potential high ***,one expanded high-resolution screening through GC Orbitrap/MS was performed for soils from petrochemical area,and another 35 PAHs were found,including alkyl-PAHs,phenyl-PAHs and other species,indicat-ing that profiles and risks of PAHs analogs in petrochemical areas deserve further expanded investigation.

关键词： Polycyclic aromatic hydrocarbons(PAHs) Derivatives Petroleum refinery Human exposure Non-targeted screening