Large-Scale Scientific Facility Research Articles

Preface: special issue on chemical measurement methodology based on large-scale scientific facility

Preface: special issue on chemical measurement methodology based on large-scale scientific facility

Search for hidden-charm tetraquark with strangeness in * *Supported in part by National Key R&D Program of China (Grant Nos. 2020YFA0406400, 2020YFA0406300); National Natural Science Foundation of China (NSFC) (Grant Nos. 11635010, 11735014, 11805086, 11835012, 11935015, 11935016, 11935018, 11961141012, 12022510, 12025502, 12035009, 12035013, 12192260, 12192261, 12192262, 12192263, 12192264, 12192265); the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; Joint

We report a search for a heavier partner of the recently observed state, denoted as , in the process , based on collision data collected at the center-of-mass energies of , 4.682 and 4.699 GeV with the BESIII detector. The is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark. A partial-reconstruction technique is used to isolate recoil-mass spectra, which are probed for a potential contribution from (). We find an excess of () candidates with a significance of , after considering systematic uncertainties, at a mass of . As the data set is limited in size, the upper limits are evaluated at the 90% confidence level on the product of the Born cross sections () and the branching fraction () of , under different assumptions of the mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies. The upper limits of are found to be at the level of pb at each energy. Larger data samples are needed to confirm the state and clarify its nature in the coming years.

Observation of the Y(4230) and a new structure in * *Supported in part by National Key R&D Program of China (2020YFA0406300, 2020YFA0406400); National Natural Science Foundation of China (NSFC) under Contracts Nos. (11625523, 11635010, 11735014, 11822506, 11835012, 11935015, 11935016, 11935018, 11961141012, 12022510, 12025502, 12035009, 12035013, 12061131003); the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; Joint Large-Scale Scientific Facility

The cross sections of at center-of-mass energies from 4.127 to 4.600 GeV are measured based on 15.6 fb data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in the line shape of the cross sections. The mass and width of the first structure are measured to be () MeV and () MeV, respectively. They are consistent with those of the established . The second structure is observed for the first time with a statistical significance greater than 8σ, denoted as . Its mass and width are determined to be () MeV and () MeV, respectively. The first presented uncertainties are statistical and the second ones are systematic. The product of the electronic partial width with the decay branching fraction is reported.

Charmless two-body B meson decays in the perturbative QCD factorization approach* *Supported by the National Science Foundation of China (11805060, 11975112, 12105028, 12070131001, 11775117), the Joint Large-Scale Scientific Facility Funds of the NSFC and CAS (U1932110), the Natural Science Foundation of Jiangsu Province (BK20200980) and the National Key Research and Development Program of China (2020YFA0406400)

The perturbative quantum chromodynamics (PQCD) approach based on factorization has resulted in great achievements in the QCD calculation of hadronic B decays. By regulating the endpoint divergence by the transverse momentum of quarks in the propagators, one can perform the perturbation calculation for various diagrams, including annihilation type diagrams. In this paper, we review the current status of the PQCD factorization calculation of two-body charmless U decays up to next-to-leading order (NLO) QCD corrections. Two new power suppressed terms in the decaying amplitudes are also considered. Using universal input (non-perturbative) parameters, we collect the branching ratios and asymmetry parameters of all charmless two body B decays, which are calculated in the PQCD approach up to NLO. The results are compared with those of the QCD factorization approach, soft-collinear effective theory approach, and current experimental measurements. For most of the considered B meson decays, the PQCD results for branching ratios agree well with those of other approaches and experimental data. The PQCD predictions for the asymmetry parameters of many of the decay channels do not agree with those of other approaches but have better agreement with experimental data. The longstanding puzzle regarding the pattern of the direct CP asymmetries of penguin-dominated decays can be understood after the inclusion of NLO contributions in PQCD. The NLO corrections and power suppressed terms play an important role in color suppressed and pure annihilation type B decay modes. These rare decays are more sensitive to different types of corrections, providing an opportunity to examine the factorization approach with more precise experimental measurements.

Machine learning enabled fast evaluation of dynamic aperture for storage ring accelerators

For any storage ring-based large-scale scientific facility, one of the most important performance parameters is the dynamic aperture (DA), which measures the motion stability of charged particles in a global manner. To date, long-term tracking-based simulation is regarded as the most reliable method to calculate DA. However, numerical tracking may become a significant issue, especially when a plethora of candidate designs of a storage ring need to be evaluated. In this paper, we present a novel machine learning-based method, which can reduce the computation cost of DA tracking by approximately one order of magnitude, while keeping sufficiently high evaluation accuracy. Moreover, we demonstrate that this method is independent of concrete physical models of a storage ring. This method has the potential to be applied to similar problems of identifying irregular motions in other complex dynamical systems.

Using as a spin polarimeter * *Partly supported by the National Natural Science Foundation of China NSFC (11875262, 11875115), Joint Large-Scale Scientific Facility Funds of the NSFC and Chinese Academy of Sciences (U2032110)

Polarization transfer measurement plays an important role in the search for new physics processes in charmed baryon decays. The measurement of the decay is suggested as a spin polarimeter. A general description of the decay is developed using Euler angles, and the polarization parameters are derived. Its relationship with parity violation is found using the phenomenological amplitude model. A Monte-Carlo simulation is performed, and the results show that charmed baryon polarization is well determined using a set of Monte-Carlo events with selected asymmetry parameters. The experimental measurement of these asymmetry parameters is suggested.

The feasibility of jet fan-assisted ventilation for temperature control of heating belts on a downward-facing sphere in a scientific facility

To avoid the deformation of the large-scale scientific facility for neutrinos detection due to temperature changes, the heat generated during the top-down annealing of the inorganic glass panels needs to be released in time to maintain temperature control of 21±1°C in the built-up area. Due to the unique shape and the changing heating sources, a novel ventilation strategy that combines jet fans with general ventilation was proposed to satisfy the special environmental control requirement. A small-scale field experiment was conducted to obtain the CFD methods for simulation. Then, the feasibility of the jet fan-assisted ventilation system was discussed in terms of two thermal control zones based on the distance from the heat source. Besides, the effectiveness of the proposed ventilation design was compared with traditional general ventilation with air-conditioned air supplied from the hall ceiling and directly opposite the heating belt based on the temperature and velocity distribution. The results show that: the area outside the thermal control range under jet fan-induced ventilation was reduced by around 60%, and the maximum temperature fluctuated over time within 0.33°C. These results provide a preliminary insight into the use of jet fan-assisted ductless ventilation to achieve precision local temperature control in a large space.

Study of C parity violating and strangeness changing J/ψ → PP weak decays * *Supported by the National Natural Science Foundation of China (11705047, 11981240403, U1632109, 11547014, 11875122), the Program for Innovative Research Team in University of Henan Province (19IRTSTHN018), the Excellent Youth Foundation of Henan Province (212300410010) and the Chinese Academy of Sciences Large-Scale Scientific Facility Program (1G2017IHEPKFYJ01)

Although weak decays are rare, they are possible within the standard model of elementary particles. Inspired by the potential prospects of the future intensity frontier, the C parity violating , decays and the strangeness changing , decays are studied via the perturbative QCD approach. It is determined that the decays have relatively large branching ratios, approximately on the order of , which might be within the measurement capability and sensitivity of the future STCF experiment.

Concurrent Structural and Electronic Phase Transitions in V2O3 Thin Films with Sharp Resistivity ChangeSupported by the National Key R&D Program of China (Grant No. 2017YFA0403600), and Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences Large-Scale Scientific Facility (Grant No. U1532149).

The relationship between structural and electronic phase transitions in V2O3 thin films is of critical importance for understanding of the mechanism behind metal–insulator transition (MIT) and related technological applications. Despite being extensively studied, there are currently no clear consensus and picture of the relation between structural and electronic phase transitions so far. Using V2O3 thin films grown on r-plane Al2O3 substrates, which exhibit abrupt MIT and structural phase transition, we show that the electronic phase transition occurs concurrently with the structural phase transition as revealed by the electrical transport and Raman spectra measurements. Our result provides experimental evidence for clarifying this issue, which could form the basis of theoretical studies as well as technological applications in V2O3.

Design and optimization study of a duoplasmatron ion source for high-intensity proton beam

Nanjing Proton Source (NPS) is a high-intensity superconducting accelerator large-scale scientific facility proposed by Nanjing University. As the advanced research project, a low-energy injector is going to be set up at the first stage. In consideration of stable performance and low cost, a duoplasmatron ion source is chosen to provide 50 keV, 40 mA proton beam for the downstream RFQ matching by a low-energy beam transport (LEBT). The duoplamatron is designed based on the existing plasma reservoir structure and optimized for low RMS emittance. The paper mainly describes the design work about the plasma generation system and the optimization study of a triode extraction system for minimizing the normalized RMS emittance. The simulation shows that a slightly concave plasma meniscus contributes to improving beam qualities. At present, the duoplasmatron source and beam diagnostics have been set up, and the source prototype is on commissioning.

Classical-field description of Bose–Einstein condensation of parallel light in a nonlinear optical cavity* *Project supported by the Graduate Science and Technology Innovation Project of Shanxi Normal University (Grant No. 01053011) and the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program (Grant No. 1G2017IHEPKFYJO1).

We study the Bose–Einstein condensation of parallel light in a two-dimensional nonlinear optical cavity, where the massive photons are converted into photon molecules (p-molecules). We extend the classical-field method to provide a description of the two-component system, and we also derive a coupled density equation which can be used to describe the conversion relation between photons and p-molecules. Furthermore, we obtain the chemical potential of the system, and we also find that the system can transform from the mixed photon and p-molecule condensate phase into a pure p-molecule condensate phase. Additionally, we investigate the collective excitation of the system. We also discuss the problem how the spontaneous decay of an atom is influenced by both the phase transition and collective excitation of the coupling system.

Drafting an Electrostatic Charge Control Plan for a Large Scale Scientific Instrument: Guidelines and a Case Study

Large-scale scientific instruments strongly support top-level research all around the world. Besides their intrinsic merits, they often play a valuable role as pathfinders for developing and testing instrumentation and as training grounds for young researchers. Strategies and roadmaps for these facilities have become a priority for a number of private and public funding organizations. Despite the large amount of mature work done in the industrial arena, it is difficult to find documents providing clear and concise orientation on how to prevent or minimize the damage caused by electrostatic discharges (ESD) in research infrastructure. This paper aims to gather all this information to develop a static charge control plan for a large-scale scientific facility. The specific case of the static charge control plan for the installation of CTA-LST telescopes is added as an example and verification of the actual applicability of the measures proposed in this document, providing static charge in human body monitoring measurements. Specific tests performed on equipment with ESD sensitive components are also described, which helped to assess any possible damage.

Verification Protocols for the Lightning Protection of a Large Scale Scientific Instrument in Harsh Environments: A Case Study

This paper is devoted to the study of the most suitable protocols needed to verify the lightning protection and ground resistance quality in a large-scale scientific facility located on a site with high risk of lightning strikes. We illustrate this work by reviewing a case study: the largest telescopes of the Northern Hemisphere Cherenkov Telescope Array, CTA-N. This array hosts sensitive and high-speed optoelectronics instrumentation and sits on a clear, free from obstacle terrain at around 2400 m above sea level. The site offers a top-quality sky but also features challenging conditions for a lightning protection system: the terrain is volcanic and has electrical resistivities well above 1 kOhm·m. In addition, the environment often exhibits humidities well below 5%, and strong winds pose challenging conditions. On the other hand, the high complexity of a Cherenkov telescope structure does not allow a straightforward application of lightning protection standards. We describe here how the risk assessment of direct strike impacts was made and how contact voltages and ground system were both tested. Finite Element Simulation (COMSOL Multiphysics) has been used to estimate the current flowing through the parts of the earthing system designed for the telescopes in the case of a direct strike impact. This work is intended to provide assistance to scientists and managers involved in the construction of scientific installations, particularly those in charge of defining verifiable reliability and safety requirements for lightning protection.

Study of BESIII trigger efficiencies with the 2018 J/ψ data * *Supported in part by National Key Basic Research Program of China (2015CB856700); National Natural Science Foundation of China (NSFC) (11625523, 11635010, 11735014, 11822506, 11835012, 11935015, 11935016, 11935018, 11961141012); the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; Joint Large-Scale Scientific Facility Funds of the NSFC and CAS (U1732263,

Using a dedicated data sample taken in 2018 on the J/ψ peak, we perform a detailed study of the trigger efficiencies of the BESIII detector. The efficiencies are determined from three representative physics processes, namely Bhabha scattering, dimuon production and generic hadronic events with charged particles. The combined efficiency of all active triggers approaches 100% in most cases, with uncertainties small enough not to affect most physics analyses.

Huizhou accelerator complex facility and its future development

This paper provides an overview of the frontier research fields and significant questions in nuclear physics regarding particle accelerators, and the status and future development trends for big-science facilities of particle accelerators are reviewed. Two Chinese government-approved “12th Five-Year” major science infrastructure facilities, the “High Intensity heavy-ion Accelerator Facility (HIAF)” and “China Initiative Accelerator Driven System (CiADS)”, are being constructed in Huizhou, Guangdong Province. Based on these two big-science projects (HIAF and CiADS), we proposed to establish a large-scale charged particle accelerator complex facility named the “Bright Electron and Ion research Facility (BEIF).” This facility will be dedicated to the research and development of nuclear physics and its interdisciplinary frontier fields. The research frontier fields of nuclear physics at the BEIF will include nuclear structure and astrophysics, nucleon structure, quark matter phase structure, and interdisciplinary fields between several significant frontiers of fundamental and nuclear physics, such as highly charged atomic physics and heavy ion-driven high energy density physics. BEIF will be a large-scale scientific complex facility comprising several superconducting ion LINAC accelerators, synchrotrons, storage rings, reactors, and various large experimental detectors and setups. BEIF will be built in three construction phases and will become one of the premier global large-scale particle accelerator complex facilities dedicated to the research of nuclear physics and technology.

Research program of nuclear astrophysics based on the HIAF

Nuclear astrophysics is an interdisciplinary research field integrating nuclear physics, astrophysics and astronomy. It has always been an important frontier of physics in the world. This paper summarizes the current status, key research topics, and experimental approaches in nuclear astrophysics and briefly introduces its research prospect based on the High Intensity heavy-ion Accelerator Facility (HIAF), which is a large-scale scientific facility for nuclear physics that is under construction in China. HIAF has great advantages for studying the masses, half-life, and reaction cross sections of the unstable nuclides and will provide a good opportunity for understanding explosive nuclear processes as well as the origin of heavy elements in the universe. For key reactions in the nucleosynthesis process, indirect measurement methods and experimental techniques such as ANC, Oslo, surrogate reactions, and surrogate ratio methods, will be developed and used for the systematic studies on the charged-particle or neutron capture reactions. Using the HIAF storage ring, the mass of the r-process nuclides can be systematically measured. Using the HIAF secondary beam line and high-efficiency detector, the decay half-life of the r-process nuclides can be measured. Furthermore, based on HIAF, the equations of states of a neutron star and weak interaction rates can be studied. Using the above nuclear physics experimental and theoretical research, the database of the masses and reaction rates will be updated. Astronomical observations will be combined to test the astrophysical model, and to understand the evolution of stars as well as the origin of elements in the universe.

Vacuum-Ultraviolet Photon Detections.

Vacuum-ultraviolet (VUV) photon detection technology is an effective means for the exploration in the field of space science (monitoring the formation and evolution of solar storms), high-energy physics (dark matter detection), large-scale scientific facility (VUV free electron lasers) and electronic industry (high-resolution lithography). The advancement of this technology mainly depends on the performance optimization of VUV photodetectors. In this review, we introduced the research progress on the typical VUV photodetectors based on scintillator, photomultiplier tube, semiconductor, and gas, with their unique advantages and optimal performance indicators in different applications summarized. In particular, during recent years, thanks to the advances in ultra-wide bandgap semiconductors, economical VUV photodetectors with low power consumption and small size have been encouragingly developed. Finally, we pointed out the remaining challenges for each type of VUV detector, with the aim of maximizing the performance in a variety of applications in the future.

Polarization in decays * * Supported by the National Natural Science Foundation of China (11875262, 11805037, 11705078), Joint Large-Scale Scientific Facility Funds of the NSFC and CAS (U1832121), Shanghai Pujiang Program (18PJ1401000) and Open Research Program of Large Research Infrastructures (2017), Chinese Academy of Sciences

Measurements of decay asymmetry parameters of charmed baryons, e.g., , provide more data to test the W-emission and W-exchange mechanisms controlled by strong and weak interactions. Taking advantage of the spin polarization in charmed baryon decays, we investigate the possibility to measure weak decay asymmetry parameters in the process. We analyze the transverse polarization spontaneously produced in this process and the spin transfer in the subsequent decays. The sensitivity to measure the asymmetry parameters is estimated for the decay .

Research on the Spatial Layout of Science Park based on Large-scale Scientific Facilities: A Case Study of Spallation Neutron Source

A large-scale scientific facility is an essential driving force for innovation in science and technology in the country. A reasonably spatial layout for the development of a science park is a vital assurance for its function positioning. Furthermore, the function of the science park determines the setting of related industries and the way of spatial layout. Based on the first-hand information of the Harwell Campus in England, this paper first analyzes the functions of the Spallation Neutron Source, a benchmark science park, and then determines the internal space elements about the positioning function. Finally, based on the spatial distribution theory and the analysis of the spatial layouts of benchmark international science parks such as Harwell Campus in England, Silicon Valley and Oak Bridge in the United States, and Proton Accelerator Research Complex in Japan, the paper proposes layouts for setting up external resource-embedded and internal center proliferation projects.

Nonvolatile Resistive Switching and Physical Mechanism in LaCrO3 Thin Films**Supported by the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences’ Large-Scale Scientific Facility under Grant No U1532149, and the National Basic Research Program of China under Grant No 2014CB931704.

Polycrystalline LaCrO3 (LCO) thin films are deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used as the switching material to construct resistive random access memory devices. The unipolar resistive switching (RS) behavior in the Au/LCO/Pt devices exhibits a high resistance ratio of ∼ 104 between the high resistance state (HRS) and low resistance state (LRS) and exhibits excellent endurance/retention characteristics. The conduction mechanism of the HRS in the high voltage range is dominated by the Schottky emission, while the Ohmic conduction dictates the LRS and the low voltage range of HRS. The RS behavior in the Au/LCO/Pt devices can be understood by the formation and rupture of conducting filaments consisting of oxygen vacancies, which is validated by the temperature dependence of resistance and x-ray photoelectron spectroscopy results. Further analysis shows that the reset current IR and reset power IR in the reset processes exhibit a scaling law with the resistance in LRS (R0), which indicates that the Joule heating effect plays an essential role in the RS behavior of the Au/LCO/Pt devices.