[en] We search for the ψ(4S) state in the B^±→ηJ/ψK^± and e⁺e^-→ηJ/ψ processes based on the Belle measurements with the assumed mass M = (4230±8) MeV/c² and width Γ = (38±12) MeV. No significant signal is observed in the ηJ/ψ mass spectra. The 90% confidence level upper limit on the product branching fraction B(B^±→ψ(4S)K^±)B(ψ(4S)→ηJ/ψ) < 6.8 × 10^-6 is obtained in the B^±→ηJ/ψK^± decays. By assuming the partial width of ψ(4S)→e⁺e^- to be 0.63 keV, a branching fraction limit B(ψ(4S)→ηJ/ψ) < 1.3% is obtained at the 90% confidence level in e⁺e^-→ηJ/ψ, which is consistent with the theoretical prediction. (authors)

[en] Considering the effects of aging on the existing Inner Drift Chamber (IDC) of BESIII, a GEM-based inner tracker, the Cylindrical-GEM Inner Tracker (CGEM-IT), is proposed to be designed and constructed as an upgrade candidate for the IDC. This paper introduces a full simulation package for the CGEM-IT with a simplified digitization model, and describes the development of software for cluster reconstruction and track fitting, using a track fitting algorithm based on the Kalman filter method. Preliminary results for the reconstruction algorithms which are obtained using a Monte Carlo sample of single muon events in the CGEM-IT, show that the CGEM-IT has comparable momentum resolution and transverse vertex resolution to the IDC, and a better z-direction resolution than the IDC. (authors)

[en] The neutrino detector of the Jiangmen Underground Neutrino Observatory (JUNO) is designed to use 20 kilotons of liquid scintillator and approximately 1600020 inch photomultipliers (PMTs). One of the options is to use the 20 inch R12860 PMT with high quantum efficiency which has recently been developed by Hamamatsu Photonics. The performance of the newly developed PMT preproduction samples is evaluated. The results show that its quantum efficiency is 30% at 400 nm. Its Peak/Valley (P/V) ratio for the single photoelectron is 4.75 and the dark count rate is 27 kHz at the threshold of 3 mV while the gain is at 1 × 10⁷. The transit time spread of a single photoelectron is 2.86 ns. Generally the performances of this new 20 inch PMT are improved over the old one of R3600. (authors)

[en] Magnetic alloy (MA)-loaded cavities have been widely used in compact proton and heavy-ion synchrotrons, and the MA core is the key issue in their development. Chinese-produced MA has never yet been adopted as core material for an MA-loaded cavity. To use Chinese-produced MA as the core material, it is necessary to study its properties, and compare with MA material produced elsewhere. In this paper, the properties of several MA cores made of Chinese-produced material are measured. Based on the measured results, a schematic design is produced for a cavity which could obtain 1 kV gap voltage with less than 1.5 kW power dissipation in the frequency range of 0.5-7 MHz. The difference between resonant frequencies obtained from simulation and analytical results is less than 10%. (authors)

[en] The total ionizing radiation (TID) response of commercial NPN silicon germanium hetero-junction bipolar transistors (SiGe HBTs) produced domestically are investigated under dose rates of 800 mGy(Si)/s and 1.3 mGy(Si)/s with a Co-60 gamma irradiation source. The changes of transistor parameters such as Gummel characteristics, and excess base current before and after irradiation, are examined. The results of the experiments show that for the KT1151, the radiation damage is slightly different under the different dose rates after prolonged annealing, and shows a time dependent effect (TDE). For the KT9041, however, the degradations of low dose rate irradiation is higher than for the high dose rate, demonstrating that there is a potential enhanced low dose rate sensitivity (ELDRS) effect for the KT9041. The possible underlying physical mechanisms of the different dose rates responses induced by the gamma rays are discussed. (authors)

[en] An experiment concerned with bypass flow between core barrel and core shroud was carried out. Not only resistance characteristics of bypass flow but also bypass mass flow rate proportion corresponding to original pressure drop of core under different orifice diameters of core shroud support plate were investigated. It is found that when orifice diameter is 1.2 times larger than the minimum orifice in experiment, bypass mass flow rate exceeds 0.5% of total core mass flow rate under reference core pressure drop condition. Otherwise the bypass mass flow rate is less than 0.5% of total core mass flow rate under other orifice diameters conditions. (authors)

[en] In order to develop high-performance fuel assemblies, resistance characteristics of spacer grid are directly related to thermal performance and hydraulic compatibility of fuel assemblies. Based on basic principles of flow resistance, the calculation model of local resistance characteristics for 5 × 5 spacer grids was studied and built by using CFD method and the calculation results were validated. The results show that the local resistance coefficients from calculation model are generally in agreement with those from direct simulation. (author)

[en] A three-dimensional computational fluid dynamic code CYCAS was developed for hydrogen safety analysis. The code solved three-dimensional, compressible and unsteady Navier-Stokes equations by the numerical method of implicit continuous Eulerian-arbitrary Lagrangian Eulerian. Multi-component mass conservation equations were solved to describe the diffusion and mixing phenomenon. A homogeneous equilibrium model was applied to model the phase change of water vapor in the fluid flow. For the phase change near the wall, the Chilton-Colburn empirical analogy was used. Algebraic and k-ε turbulence models were employed to model the turbulent flow. The turbulent jet experiment HYJET and the international standard problem ISP23 were simulated and analyzed for CYCAS validation. The computational results agree well with the experimental data. (authors)

[en] Based on levelized cost of electricity (LCOE) method, the fuel cycle was selected as the object of the study, the economics of once-through fuel cycle and twice-through fuel cycle for travelling wave reactor (TWR) was studied. Ten important economic and technical parameters were proposed for the sensitivity analysis. The results show that the LCOE of TWR is lower than that of conditional light water reactor and fast reactor. Furthermore, the LCOE of once-through fuel cycle of TWR is lower than that of twice-through cycle. The sensitivity analysis indicates that the discount rate, burn-up, overnight cost and thermal efficiency impact the LCOE severely, while the price of uranium and the cost of waste disposal barely impact the LCOE. (authors)

[en] As partial verification that the original size module of China helium-cooled solid breeder (CH-HCSB) test blanket module (TBM) was reasonable and the development process was feasible, fabrication work of a small sized module was to be carried out targetably. The detailed design and structure analysis of small sized TBM was carried out based on preliminary design work, fabrication process and integrated assembly process was proposed, so it lay a solid foundation for the engineering fabrication of TBM. (authors)