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J. Zhao

Publications and source records attributed to J. Zhao.

At least 37 records · Page 2Linked to original sources
arXiv2025

CMS RPC Non-Physics Event Data Automation Ideology

This paper presents a streamlined framework for real-time processing and analysis of condition data from the CMS experiment Resistive Plate Chambers (RPC). Leveraging data streaming, it uncovers correlations between RPC performance metrics, like currents and rates, and LHC luminosity or environmental conditions. The Java-based framework automates data handling and predictive modeling, integrating extensive datasets into synchronized, query-optimized tables. By segmenting LHC operations and analyzing larger virtual detector objects, the automation enhances monitoring precision, accelerates visualization, and provides predictive insights, revolutionizing RPC performance evaluation and future behavior modeling.

hep-ex↗
arXiv2025

Bound-State Beta Decay of $\mathbf{\mathrm{^{205}{Tl}^{81+}}}$ Ions and the LOREX Project

Stable $^{205}$Tl ions have the lowest known energy threshold for capturing electron neutrinos ($ν_e$) of ${ E}_{ν_e}\ge50.6$\,keV. The Lorandite Experiment (LOREX), proposed in the 1980s, aims at obtaining the longtime averaged solar neutrino flux by utilizing natural deposits of Tl-bearing lorandite ores. To determine the $ν_e$ capture cross section, it is required to know the strength of the weak transition connecting the ground state of $^{205}$Tl and the 2.3 keV first excited state in $^{205}$Pb. The only way to experimentally address this transition is to measure the bound-state beta decay ($β_{b}$) of fully ionized $\mathrm{^{205}Tl^{81+}}$ ions. After three decades of meticulous preparation, the half-life of the $β_{b}$ decay of $\mathrm{^{205}Tl^{81+}}$ has been measured to be $291_{-27}^{+33}$ days using the Experimental Storage Ring (ESR) at GSI, Darmstadt. The longer measured half-life compared to theoretical estimates reduces the expected signal-to-noise ratio in the LOREX, thus challenging its feasibility.

nucl-ex↗
arXiv2024

High-temperature $^{205}$Tl decay clarifies $^{205}$Pb dating in early Solar System

Radioactive nuclei with lifetimes on the order of millions of years can reveal the formation history of the Sun and active nucleosynthesis occurring at the time and place of its birth. Among such nuclei whose decay signatures are found in the oldest meteorites, $^{205}$Pb is a powerful example, as it is produced exclusively by slow neutron captures (the s process), with most being synthesized in asymptotic giant branch (AGB) stars. However, making accurate abundance predictions for $^{205}$Pb has so far been impossible because the weak decay rates of $^{205}$Pb and $^{205}$Tl are very uncertain at stellar temperatures. To constrain these decay rates, we measured for the first time the bound-state $β^-$ decay of fully ionized $^{205}$Tl$^{81+}$, an exotic decay mode that only occurs in highly charged ions. The measured half-life is 4.7 times longer than the previous theoretical estimate and our 10% experimental uncertainty has eliminated the main nuclear-physics limitation. With new, experimentally backed decay rates, we used AGB stellar models to calculate $^{205}$Pb yields. Propagating those yields with basic galactic chemical evolution (GCE) and comparing with the $^{205}$Pb/$^{204}$Pb ratio from meteorites, we determined the isolation time of solar material inside its parent molecular cloud. We find positive isolation times that are consistent with the other s-process short-lived radioactive nuclei found in the early Solar System. Our results reaffirm the site of the Sun's birth as a long-lived, giant molecular cloud and support the use of the $^{205}$Pb--$^{205}$Tl decay system as a chronometer in the early Solar System.

nucl-ex↗
arXiv2024

Evidence for the $^{15}\text{Be}$ ground state from $^{12}$Be$+3$n events

Background: $^{15}$Be is an unbound nuclide that has been observed to decay by one-neutron emission. Shell model calculations predict two low-lying states in its energy spectrum, however, only a single resonance has been observed from coincident measurements of $^{14}$Be+n. It has been suggested that the yet unobserved state may decay sequentially through the first excited state in $^{14}$Be followed by a two-neutron emission to $^{12}$Be. Purpose: The ground state of $^{15}$Be has yet to be confirmed. A search for this predicted $^{15}$Be state by reconstructing $^{12}$Be$+3$n events allows a possible determination of its ground state properties. Methods: A neutron-pickup reaction was performed with a $^{14}$Be beam on a CD$_2$ target to populate unbound $^{15}$Be states. Decay energies were reconstructed using invariant mass spectroscopy by detecting $^{12}$Be daughter nuclei in coincidence with up to three neutrons. Results: Evidence for at least one resonance in $^{15}$Be is presented based on the reconstruction of $^{12}$Be$+3$n events. Through comparison with simulations, the energy of the strongest resonance in the analyzed reaction and decay channel is determined to be $E_{^{12}Be+3n}=330(20)$ keV. Conclusions: The inclusion of a new $^{15}$Be state among the $^{12}$Be+$3$n events lower in relative decay energy than the previous $^{14}$Be+n observations provides the best fit to the data. Because this suggested new state would be lower in energy than the previously observed state, it is a candidate for the ground state of $^{15}$Be.

nucl-ex↗
arXiv2024

Giant interfacial Dzyaloshinskii-Moriya Interaction in perovskite La_{0.7}Sr_{0.3}MnO_{3} films

The Dzyaloshinskii-Moriya interaction (DMI) plays a critical role in stabilizing topological spin textures, a key area of growing interest in oxide-based spintronics. While most of reported topological phenomena found in manganites are related to the bulk-like DMI, the understanding of interfacial DMI and its origin in oxide interfaces remain limited. Here we experimentally investigate the interfacial DMI of La_{0.7}Sr_{0.3}MnO_{3} (LSMO) films grown on various substrates by employing spin-wave propagation with drift velocities at room temperature. Our findings reveal a giant interfacial DMI coefficient (\mathit{D} _{s}) of 1.96 pJ/m in LSMO/NdGaO_{3}(110) system, exceeding previously reported values in oxides by one to two orders of magnitude. First-principles calculations further show that with the aid of 6\mathit{s} electrons, the 4\mathit{f} electrons from Nd play a key role in enhancing the spin-orbit coupling of the 3\mathit{d} electrons in Mn, ultimately leading to the observed giant interfacial DMI. This discovery of giant interfacial DMI through engineering the interface of oxides provides valuable insights for advancing functional chiral magnonics and spintronics.

cond-mat.mtrl-sci↗
arXiv2024

Color-switching in an optical parametric oscillator using a phase-conjugate mirror

We construct a phase-conjugate resonator which passively produces stable pulses that alternate between the probe and the conjugate colors. The requisite phase-conjugate mirror inside the resonator is constructed using non-degenerate four-wave mixing (4WM) in rubidium vapor. The glancing-angle phase-conjugate mirror is a 100\% output coupler, and therefore this resonator is unusual in that no light circulates the cavity more than once. Without the gain of the phase-conjugate mirror, the cavity boundary conditions, and thus resonant modes, are not defined and therefore can be tuned by the pump. The output of the optical parametric oscillator that is formed above threshold can passively mode-lock. The phase-conjugate mirror removes thermal or acoustic instabilities that are on a MHz or slower timescale. This work provides a new method for stable pulsing using phase-conjugate optics, and suggests a platform for producing mode-locked pulses with squeezed light, as the 4WM process has already demonstrated quantum correlations.

physics.optics↗
arXiv2024

Coherent Transfer of Lattice Entropy via Extreme Nonlinear Phononics in Metal Halide Perovskites

Entropy transfer in metal halide perovskites, characterized by significant lattice anharmonicity and low stiffness, underlies the remarkable properties observed in their optoelectronic applications, ranging from solar cells to lasers. The conventional view of this transfer involves stochastic processes occurring within a thermal bath of phonons, where lattice arrangement and energy flow from higher to lower frequency modes. Here we unveil a comprehensive chronological sequence detailing a conceptually distinct, coherent transfer of entropy in a prototypical perovskite CH$_3$NH$_3$Pbl$_3$. The terahertz periodic modulation imposes vibrational coherence into electronic states, leading to the emergence of mixed (vibronic) quantum beat between approximately 3 THz and 0.3 THz. We highlight a well-structured, bi-directional time-frequency transfer of these diverse phonon modes, each developing at different times and transitioning from high to low frequencies from 3 to 0.3 THz, before reversing direction and ascending to around 0.8 THz. First-principles molecular dynamics simulations disentangle a complex web of coherent phononic coupling pathways and identify the salient roles of the initial modes in shaping entropy evolution at later stages. Capitalizing on coherent entropy transfer and dynamic anharmonicity presents a compelling opportunity to exceed the fundamental thermodynamic (Shockley-Queisser) limit of photoconversion efficiency and to pioneer novel optoelectronic functionalities.

cond-mat.mtrl-sci↗
arXiv2024

Research on the Evaluation Index System of Enterprise Production Efficiency

This paper focuses on studying the evaluation index system for the production efficiency of tobacco enterprises. Considering the limitations of existing evaluation methods in accurately assessing the production quality of cigarette enterprises, a mathematical model based on the Analytic Hierarchy Process (AHP) is established. This model constructs an evaluation framework for the production efficiency of cigarette enterprises and subsequently analyzes the significance of each index within this framework. To comprehensively analyze the multi-index and feasibility aspects of the selected projects, the AHP method is employed to establish a comprehensive feasibility research and evaluation structure model. The result of this feasibility study provides the conclusion that the construction of an evaluation index system for the production efficiency of cigarette enterprises can indeed promote the enhancement of their production efficiency.

math.OC↗
arXiv2024

Comparative Study of Quarkonium Transport in Hot QCD Matter

This document summarizes the efforts of the EMMI Rapid Reaction Task Force on "Suppression and (re)generation of quarkonium in heavy-ion collisions at the LHC", centered around their 2019 and 2022 meetings. It provides a review of existing experimental results and theoretical approaches, including lattice QCD calculations and semiclassical and quantum approaches for the dynamical evolution of quarkonia in the quark-gluon plasma as probed in high-energy heavy-ion collisions. The key ingredients of the transport models are itemized to facilitate comparisons of calculated quantities such as reaction rates, binding energies, and nuclear modification factors. A diagnostic assessment of the various results is attempted and coupled with an outlook for the future.

nucl-th↗
arXiv2024

Generalized time-dependent generator coordinate method for induced fission dynamics

The generalized time-dependent generator coordinate method (TD-GCM) is extended to include pairing correlations. The correlated GCM nuclear wave function is expressed in terms of time-dependent generator states and weight functions. The particle-hole channel of the effective interaction is determined by a Hamiltonian derived from an energy density functional, while pairing is treated dynamically in the standard BCS approximation with time-dependent pairing tensor and single-particle occupation probabilities. With the inclusion of pairing correlations, various time-dependent phenomena in open-shell nuclei can be described more realistically. The model is applied to the description of saddle-to-scission dynamics of induced fission. The generalized TDGCM charge yields and total kinetic energy distribution for the fission of 240Pu, are compared to those obtained using the standard time-dependent density functional theory (TD-DFT) approach, and with available data.

nucl-th↗
arXiv2023

Self Generated Wargame AI: Double Layer Agent Task Planning Based on Large Language Model

The large language models represented by ChatGPT have a disruptive impact on the field of artificial intelligence. But it mainly focuses on natural language processing, speech recognition, machine learning and natural language understanding. This paper innovatively applies the large language model to the field of intelligent decision-making, places the large language model in the decision-making center, and constructs an agent architecture with the large language model as the core. Based on this, it further proposes a two-layer agent task planning, issues and executes decision commands through the interaction of natural language, and carries out simulation verification through the wargame simulation environment. Through the game confrontation simulation experiment, it is found that the intelligent decision-making ability of the large language model is significantly stronger than the commonly used reinforcement learning AI and rule AI, and the intelligence, understandability and generalization are all better. And through experiments, it was found that the intelligence of the large language model is closely related to prompt. This work also extends the large language model from previous human-computer interaction to the field of intelligent decision-making, which has important reference value and significance for the development of intelligent decision-making.

cs.AI↗
arXiv2023

Lessons learned while developing the Serenity-S1 ATCA card

The Serenity-S1 is a Xilinx Virtex Ultrascale+ based Advanced Telecommunications Computing Architecture (ATCA) processing blade that has been optimised for production. It incorporates many developments from the Serenity-A and Serenity-Z prototype cards and, where possible, adopts solutions being used across CERN. It also uses many new parts because commonly used parts have disappeared from the market during the semiconductor crisis, with only some returning. Improvements to simplify manufacture, the performance of new components, some of the more difficult aspects of procurement, the performance of production-grade Samtec 25\,Gb/s optical firefly parts, and issues with the rack cooling infrastructure are discussed.

physics.ins-det↗
arXiv2023

The Multiview Observatory for Solar Terrestrial Science (MOST)

We report on a study of the Multiview Observatory for Solar Terrestrial Science (MOST) mission that will provide comprehensive imagery and time series data needed to understand the magnetic connection between the solar interior and the solar atmosphere/inner heliosphere. MOST will build upon the successes of SOHO and STEREO missions with new views of the Sun and enhanced instrument capabilities. This article is based on a study conducted at NASA Goddard Space Flight Center that determined the required instrument refinement, spacecraft accommodation, launch configuration, and flight dynamics for mission success. MOST is envisioned as the next generation great observatory positioned to obtain three-dimensional information of large-scale heliospheric structures such as coronal mass ejections, stream interaction regions, and the solar wind itself. The MOST mission consists of 2 pairs of spacecraft located in the vicinity of Sun-Earth Lagrange points L4 (MOST1, MOST3) and L5 (MOST2 and MOST4). The spacecraft stationed at L4 (MOST1) and L5 (MOST2) will each carry seven remote-sensing and three in-situ instrument suites, including a novel radio package known as the Faraday Effect Tracker of Coronal and Heliospheric structures (FETCH). MOST3 and MOST4 will carry only the FETCH instruments and are positioned at variable locations along the Earth orbit up to 20° ahead of L4 and 20° behind L5, respectively. FETCH will have polarized radio transmitters and receivers on all four spacecraft to measure the magnetic content of solar wind structures propagating from the Sun to Earth using the Faraday rotation technique. The MOST mission will be able to sample the magnetized plasma throughout the Sun-Earth connected space during the mission lifetime over a solar cycle.

astro-ph.SR↗
arXiv2023

Enhancing Functional Data Analysis with Sequential Neural Networks: Advantages and Comparative Study

Functional Data Analysis (FDA) is a statistical domain developed to handle functional data characterized by high dimensionality and complex data structures. Sequential Neural Networks (SNNs) are specialized neural networks capable of processing sequence data, a fundamental aspect of functional data. Despite their great flexibility in modeling functional data, SNNs have been inadequately employed in the FDA community. One notable advantage of SNNs is the ease of implementation, making them accessible to a broad audience beyond academia. Conversely, FDA-based methodologies present challenges, particularly for practitioners outside the field, due to their intricate complexity. In light of this, we propose utilizing SNNs in FDA applications and demonstrate their effectiveness through comparative analyses against popular FDA regression models based on numerical experiments and real-world data analysis. SNN architectures allow us to surpass the limitations of traditional FDA methods, offering scalability, flexibility, and improved analytical performance. Our findings highlight the potential of SNN-based methodologies as powerful tools for data applications involving functional data.

cs.LG↗
arXiv2023

Recent Upgrades of the Gas Handling System for the Cryogenic Stopping Cell of the FRS Ion Catcher

In this paper, the major upgrades and technical improvements of the buffer gas handling system for the cryogenic stopping cell of the FRS Ion Catcher at GSI/FAIR (in Darmstadt, Germany) are described. The upgrades include implementation of new gas lines and gas purifiers to achieve a higher buffer gas cleanliness for a more efficient extraction of reactive ions as well as suppression of the molecular background ionized in the stopping cell. Furthermore, additional techniques have been implemented for improved monitoring and quantification of the purity of the helium buffer gas.

physics.ins-det↗
arXiv2023

Strong enhancement of magnetic ordering temperature and structural/valence transitions in EuPd3S4 under high pressure

We present a comprehensive study of the mixed valent compound, EuPd3S4, by electrical transport, X-ray diffraction, time-domain 151Eu synchrotron Mössbauer spectroscopy, and X-ray absorption spectroscopy measurements under high pressure. The electrical transport measurements show that the antiferromagnetic ordering temperature, TN, increases rapidly from 2.8 K at ambient pressure to 23.5 K at ~19 GPa and plateaus between ~19 and ~29 GPa after which no anomaly associated with TN is detected. A pressure-induced first order structural transition from cubic to tetragonal is observed, with a rather broad coexistence region (~20 GPa to ~32 GPa) that corresponds to the TN plateau. Mössbauer spectroscopy measurements show a clear valence transition from approximately 50:50 Eu2+:Eu3+ to fully Eu3+ at ~28 GPa, consistent with the vanishing of the magnetic order at the same pressure. X-ray absorption data show a transition to a fully trivalent state at a similar pressure. Our results show that pressure first greatly enhances TN, most likely via enhanced hybridization between the Eu 4f states and the conduction band, and then, second, causes a structural phase transition that coincides with the conversion of the europium to a fully trivalent state.

cond-mat.str-el↗
arXiv2023

Rolling control and dynamics model of two section articulated-wing ornithopter

This paper invented a new rolling control mechanism of two section articulated-wing ornithopter, which is analogues to aileron control in plane, however, similar control mechanism leads to opposite result, indicating the ornithopter supposed to go left now go right instead. This research gives a qualitative dynamics model which explains this new phenomenon. Because of wing folding, the differential rotation of outer-section wing (analogues to aileron in plane, left aileron up and right aileron down make left turn) around pitch axis becomes common mode rotation around yaw axis,leading its rotating torque changing from left-handed rotation (using left-handed as example, right-handed is the same) around roll axis to a common mode force pointing to front-right (northeast, NE) direction from first player's view of the ornithopter.Because most of the flapping movement is in the upper hemisphere from ornithopter's view, the NE force is above on the center of mass of the orthopter, generating a right-handed moment around roll axis. Therefore, the ornithopter supposed to go left now goes right. This phenomenon is a unique and only observed in two section articulated-wing ornithopter by far. Many field tests conducted by authors confirm it is highly repetitive.

cs.RO↗