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Y. P. Zhang

Publications and source records attributed to Y. P. Zhang.

At least 19 recordsLinked to original sources

Areal-time disruption prediction and mitigation system for the EXL-50U spherical torus

This work presents a real-time disruption prediction and mitigation system developed for high-current operations in the EXL-50U Spherical Torus. By leveraging Reflective Memory (RFM) technology, the system establishes a low-latency real-time data path, creating a fully integrated pipeline that synchronizes multi-channel diagnostic acquisition, online preprocessing, real-time inference, and Massive Gas Injection (MGI) triggering. At its core, a lightweight prediction model based on a Temporal Convolutional Network (TCN) with a channel attention mechanism extracts disruption precursor features while adaptively weighting the importance of different diagnostic channels. {Tested across discharges \#14036--\#14790, the system achieves a true positive rate of 82.4\% and a false positive rate of 16.5\%, with end-to-end latency below $1~\mathrm{ms}$ in online operation.} Mitigation experiments further show that the MGI system can supply the required gas inventory and trigger a rapid post-injection plasma response, supporting the operational requirements of EXL-50U and providing engineering guidance for future devices such as EHL-2. These results confirm the engineering feasibility of integrated real-time disruption control on EXL-50U, offering a robust basis for future research in higher-parameter fusion devices.

physics.plasm-ph

Precise Measurement and Control of Radon Progeny on Detector Surfaces

In low-background particle physics experiments, surface deposition of radon progeny presents a significant background challenge. To characterize this contamination, a high-sensitivity surface $α$-activity measurement system was developed, which employs a 3$\times$3 Si-PIN array operating in vacuum to perform $α$-spectroscopy on samples. The system was calibrated using Poly(Methyl MethAcrylate) (PMMA) plates exposed to a controlled high-radon atmosphere, achieving an energy resolution of 2.09 \% for 5.30~MeV $α$ particles and a one-day measurement sensitivity of 1.27~$μ$Bq/cm$^2$ for $^{210}$Po surface activity. Using this system and a self-built high radon concentration chamber, the deposition behavior of radon progeny on PMMA surfaces was investigated. Results indicate a non-monotonic dependence on exposure time, a significant enhancement of deposition with increasing negative surface electrostatic potential, and a strong modulation by ambient humidity. This paper details the apparatus design, calibration, and experimental study of radon progeny deposition dynamics on PMMA surfaces.

physics.ins-det

A Novel Numerical Algorithms Optimization Method with Machine Learning Frameworks: Application on Real-time Plasmas Equilibrium Reconstruction in EXL-50U Spherical Torus

This work proposes for the first time a novel optimization method for numerical algorithms, which takes advantages of machine learning frameworks PyTorch and TensorRT, leveraging their modularity, low development threshold, and automatic tuning characteristics to achieve a real-time plasmas reconstruction algorithm called PTEFIT as an application in tokamak-based controlled fusion that combines performance, flexibility, and usability. The algorithm has been deployed and routinely operated on the EXL-50U spherical tokamak, with an average inference time of only 0.268ms per time slice at $129\times 129$ resolution, and has successfully driven feedback control of the maximum radial position of plasmas and isoflux control. We believe that its design philosophy has sufficient potential to accelerate development and optimization in GPU parallel computing, and is expected to be extended to other numerical algorithms.

physics.plasm-ph

Measuring short-range correlations and quasi-elastic cross sections in A(e,e') at x>1 and modest Q$^2$

We present results from the Jefferson Lab E08-014 experiment, investigating short-range correlations (SRC) through measurements of inclusive quasi-elastic scattering from $^2$H, $^3$He, $^4$He, $^{12}$C, $^{40}$Ca, and $^{48}$Ca. The kinematics were selected to isolate scattering from SRCs, yielding a plateau in the A/$^2$H cross-section ratios due to the universal two-body structure of the 2N-SRCs in light and heavy nuclei. We observe approximate plateaus in the A/$^2$H ratios and provide the first extractions of the A/$^2$H ratio for $^{40}$Ca and $^{48}$Ca. We also examine the A/$^3$He ratio, aiming to identify three-nucleon SRCs (3N-SRCs). Following the approach for isolating 2N-SRCs, searching for 3N-SRC dominance involved measuring the A/$^3$He cross section ratio at modest-to-large $Q^2$ values and looking for a plateau ratios for $x \gtorder 2.5$. This was not observed in the data, and in fact increasing $Q^2$ values moved the data \textit{further away} from the predicted plateau. We show here that, when analyzed in terms of the struck nucleon's light-cone momentum, the data exhibited the expected trend, progressively approaching the predicted 3N-SRC plateau. These observations suggest that future measurements at higher energies may facilitate a definitive isolation and identification of 3N-SRCs.

nucl-ex

Measurement of radon concentration in the output water of the 100~t/h ultrapure water system at the Jiangmen Underground Neutrino Observatory

The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purpose low background liquid scintillator detector, was proposed primarily to determine the neutrino mass ordering. To mitigate radioactivity from surrounding rock and enable cosmic muon tagging, its central detector is immersed in a Water Cherenkov Detector (WCD) containing 40~ktons of ultrapure water instrumented with 2400 20-inch micro-channel plate photomultiplier tubes. Stringent radiopurity requirements mandate a radon concentration below 10 ~mBq/m$^3$ in the WCD. To achieve this, we developed a two-stage (ground and underground) ultrapure water system with 100~t/h production capacity, integrating a five-stage degassing membrane for radon removal. A novel microbubble technique was implemented to optimize the degassing membranes' radon removal efficiency. The synergistic combination of the microbubble technology and the multistage degassing membranes achieved a radon removal efficiency exceeding 99.9\%, reducing the system's output to 0.61 $\pm$ 0.50~mBq/m$^3$ in recirculation mode, surpassing design specifications and establishing world-leading performance standards. This paper details the ultrapure system architecture, quantifies the radon contributions of each device, and presents a comprehensive study on microbubble-augmented membrane degassing for low radon ultra-pure water production in a 100~t/h water system.

physics.ins-det

Light nuclei elliptic flow at mid-rapidity in $\sqrt{s_{NN}} = 3.0-3.9$ GeV Au+Au collisions using coalescence model

Light nuclei collective flow is an important probe for understanding their production mechanisms in heavy-ion collisions. The STAR collaboration has reported that the atomic mass number ($A$) scaling of light nuclei elliptic flow $v_2$ is broken at $\sqrt{s_{NN}} = 3.0-3.9$ GeV. The observations reveals that, while protons maintain negative $v_2$ values at mid-rapidity at both 3.0 and 3.2 GeV, light nuclei $v_2$ exhibit a sign change from negative at 3.0 GeV to positive at 3.2 GeV. In this study, we investigate $v_2$ of protons and deuterons in mid-central Au+Au Collisions at $\sqrt{s_{NN}} =$ 3.0, 3.2, 3.5 and 3.9 GeV using the JAM2 microscopic transport model. Deuterons are formed via nucleon coalescence, with the spatial distance ${ΔR}$ and momentum difference ${ΔP}$ between constituent protons and neutrons serving as the coalescence criteria. Our calculations successfully reproduce the sign change in deuteron $v_2$ at 3.2 GeV. We observe a strong dependence of nucleon coalescence probability on the azimuthal angle relative to the reaction plane. This effect is primarily driven by the transverse momentum dependence of the mean spatial $\langle {ΔR} \rangle$ and momentum $\langle {ΔP} \rangle$ separations between nucleon pairs, which vary with the nucleon azimuthal angle. Moreover, our analysis demonstrates that the stiffness of the nuclear equation of state plays a crucial role in determining the energy dependence of this sign change in deuteron $v_2$ at $\sqrt{s_{NN}}=3.2$ GeV.

nucl-th

Development of low-radon ultra-pure water for the Jiangmen Underground Neutrino Observatory

The Jiangmen Underground Neutrino Observatory(JUNO) is a state-of-the-art liquid scintillator-based neutrino physics experiment under construction in South China. To reduce the background from external radioactivities, a water Cherenkov detector composed of 35~kton ultra-pure water and 2,400 20-inch photomultiplier tubes is developed. Even after specialized treatment, ultra-pure water still contains trace levels of radioactive elements that can contribute to the detector background. Among which $^{222}$Rn is particularly significant. To address this, an online radon removal system based on the JUNO prototype has been developed. By integrating micro-bubble generators to enhance degasser's radon removal efficiency, the radon concentration in water can be reduced to 1~mBq/m$^{3}$ level, meeting the stringent requirements of JUNO. Additionally, a highly sensitive online radon concentration measurement system capable of detecting concentrations $\sim$1~mBq/m$^3$ has been developed to monitor the radon concentration in water. In this paper, the details regarding both systems will be presented.

physics.ins-det

Developing a $μ$Bq/m$^{3}$ level $^{226}$Ra concentration in water measurement system for the Jiangmen Underground Neutrino Observatory

The Jiangmen Underground Neutrino Observatory (JUNO), a 20~kton multi-purpose low background Liquid Scintillator (LS) detector, was proposed primarily to determine the neutrino mass ordering. To suppress the radioactivity from the surrounding rocks and tag cosmic muons, the JUNO central detector is submerged in a Water Cherenkov Detector (WCD). In addition to being used in the WCD, ultrapure water is used in LS filling, for which the $^{226}$Ra concentration in water needs to be less than 50~$μ$Bq/m$^3$. To precisely measure the $^{226}$Ra concentration in water, a 6.0~$μ$Bq/m$^3$ $^{226}$Ra concentration in water measurement system has been developed. In this paper, the detail of the measurement system as well as the $^{226}$Ra concentration measurement result in regular EWII ultrapure water will be presented.

physics.ins-det

Semi-relativistic antisymmetrized molecular dynamics for energetic neutron production in intermediate energy heavy-ion reactions

Relativistic corrections have been made in the non-relativistic antisymmetrized molecular dynamics (AMD) simulations to apply to the high energy neutron production in the $^{12}$C+$^{12}$C and $^{16}$O+$^{12}$C collisions at incident energies of 290 and 400 MeV/nucleon. The corrections are made in kinematics alone and no nucleon-nucleon inelastic scatterings nor meson productions are taken into account, and AMD with the relativistic corrections is called semi-relativistic AMD. The three-nucleon collision (3NC) and Fermi boost in the collision processes are taken into account in the non-relativistic AMD. Since the relativistic corrections tend to compensate in each other, the difference between the semi-relativistic and non-relativistic results become small. High energy tails of the available experimental neutron double differential cross sections, especially at larger angles, are well reproduced by AMD with the 3NC term both with non-relativistic and semi-relativistic simulations. These results indicate that the high energy neutrons are dominantly produced by the 3NC process in this incident energy range.

nucl-th

System upgrade for $μ$Bq/m$^3$ level $^{222}$Rn concentration measurement

The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multipurpose underground liquid scintillator detector, was proposed for the determination of the neutrino mass hierarchy as primary physics goal. The central detector will be submerged in a water Cherenkov detector to lower the background from the environment and cosmic muons. Radon is one of the primary background sources. Nitrogen will be used in several sub-systems, and a highly sensitive radon detector has to be developed to measure its radon concentration. A system has been developed based on $^{222}$Rn enrichment of activated carbon and $^{222}$Rn detection based on the electrostatic collection. This paper presents the detail of a $μ$Bq/m$^3$ level $^{222}$Rn concentration measurement system and gives detailed information about how the adsorption coefficient was measured and how the temperature, flow rate, and $^{222}$Rn concentration affect the adsorption coefficient.

physics.ins-det

Research of radon diffusion behavior in liquid scintillator

The background caused by radon and its daughters is an important background in the low background liquid scintillator (LS) detectors. The study of the diffusion behaviour of radon in the LS contributes to the analysis of the related background caused by radon. Methodologies and devices for measuring the diffusion coefficient and solubility of radon in materials are developed and described. The radon diffusion coefficient of the LS was measured for the first time and in addition the solubility coefficient was also obtained. In addition, the radon diffusion coefficient of the polyolefine film which is consistent with data in the literature was measured to verify the reliability of the diffusion device.

physics.ins-det

A Study on the radon removal performance of low background activated carbon

Radon and radon daughters pose significant backgrounds to rare-event searching experiments. Activated carbon, which has very strong adsorption capacity for radon, can be used for radon removal and radon enrichment. The internal $^{226}$Ra concentration ultimately limits its radon enrichment ability. In order to measure the intrinsic background and study the radon adsorption capability of Saratech activated carbon at various temperatures, a radon-emanation measurement system with a high-sensitivity radon detector and an adsorption-performance research-system have been developed. In this paper, a 0.71~mBq/m$^3$ high-sensitivity radon detector and measurement details of the radon-adsorption capability of Saratech activated carbon at low temperature will be presented.

physics.ins-det

Characterization of VUV4 SiPM for Liquid Argon Detector

Particle detectors based on liquid argon are now recognised as an attractive technology for dark matter direct detection and coherent elastic neutrino-nucleus scattering measurement. A program using a dual-phase liquid argon detector with a fiducial mass of 200~kg to detect coherent elastic neutrino-nucleus scattering at Taishan Nuclear Power Plant has been proposed. SiPMs will be used as the photon sensor because of their high radio-purity and high photon detection efficiency. S13370-6050CN SiPM, made by Hamamatsu, is a candidate for the detector. In this paper, the characterisation of S13370-6050CN SiPM, including the cross talk and after pulse probabilities at liquid argon temperature and the temperature dependence of break down voltage, dark counting rate and relative quantum efficiency were presented.

physics.ins-det

Using $^{22}$Na and $^{83{\rm m}}$Kr to calibrate and study the properties of scintillation in xenon-doped liquid argon

We have measured the properties of scintillation light in liquid argon doped with xenon concentrations from 165 ppm to 10,010 ppm using a $^{22}$Na source. The energy transfer processes in the xenon-doped liquid argon are discussed in detail, and a new waveform model is established and used to fit the average waveform. The time profile of the scintillation photon in the xenon-doped liquid argon and of the TPB emission are presented. The quantities of xenon-doped are controlled by a Mass Flow Controller which is calibrated via a Redusial Gas Analyzer to ensure that the xenon concentration is accurate. In addition, a successful test of $^{83{\rm m}}$Kr as a calibration source has been implemented in the xenon-doped liquid argon detector for the first time. By comparing the light yield of the $^{22}$Na and $^{83{\rm m}}$Kr, it can be concluded that the scintillation efficiency is almost same over the range of 41.5 keV to 511 keV.

physics.ins-det

Comparison on PMT Waveform Reconstructions with JUNO Prototype

JUNO is proposed to determine the neutrino mass hierarchy and rich in many other neutrino topics. A prototype is designed and set up for better understanding sub-systems of future detector. The preliminary results show that its threshold reaches ~0.3MeV with trigger rate ~290 Hz on the ground with cosmic muon rate ~35 Hz. Aiming for a better detector understanding from PMT signal, three reconstruction algorithms are compared for PMT waveforms with different overshoot ratios, including charge integration, waveform fitting, and deconvolution. It is concluded that the three methods have similar performance on uncertainty and systematic bias while deconvolution algorithm is best to handle larger overshoot and the simplest charge integration could be considered with controlled overshoot for future fast preliminary reconstruction.

physics.ins-det

The water system and radon measurement system of Jiangmen Underground Neutrino Observatory

The Jiangmen Underground Neutrino Observatory (JUNO), a 20ktons multi-purpose underground liquid scintillator detector, was proposed with the determination of the neutrino mass hierarchy as a primary physics goal. Due to low background requirement of the experiment, a multi-veto system ,which consists of a water Cherenkov detector and a top tracker detector, is required. In order to keep the water quality good and remove the radon in the water, a ultra-pure water system, a radon removal system and radon concentration measurement system have been designed. In this paper, the radon removal equipments and its radon removal limit will be presented.

physics.ins-det

The development of $^{222}$Rn detectors for JUNO prototype

The radioactive noble gas $^{222}$Rn, which can be dissolved in water, is an important background source for JUNO. In this paper, based on the water system of JUNO prototype, two kinds of high sensitivity radon detectors have been proposed and developed. The sensitivity of Si-PIN Rn detector, which uses a Si-PIN photodiode to detect the $α$ from $^{214}$Po decay, is $\sim$9.0~mBq/m$^3$. The sensitivity of LS Rn detector, which uses liquid scintillator to detect the coincident signals of $β$ from $^{214}$Bi decay and $α$ from $^{214}$Po decay, is $\sim$64.0~mBq/m$^3$. Both of the two kinds of Rn detector have the potential to be developed as an online Rn concentration monitoring equipment for JUNO veto detector.

physics.ins-det

An algorithm to resolve γ-rays from charged cosmic rays with DAMPE

The DArk Matter Particle Explorer (DAMPE), also known as Wukong in China, launched on December 17, 2015, is a new high energy cosmic ray and γ-ray satellite-borne observatory in space. One of the main scientific goals of DAMPE is to observe GeV-TeV high energy γ-rays with accurate energy, angular, and time resolution, to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays, it is challenging to identify γ-rays with sufficiently high efficiency minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations, using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at $\sim10$ GeV amounts to less than 1% of the selected sample. Finally, we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar.

physics.ins-det