242 Search Results

This work presents timing measurements of 4H-SiC Low Gain Avalanche Detectors (4H-SiC LGADs) using beta particles from a 90Sr source. The 4H-SiC LGADs exhibit fast signal responses, and a time resolution of 61 ps was achieved, comparable to that of standard Si LGADs. The present limitation in the time resolution of 4H-SiC LGADs appears to stem from limited charge generation. Nevertheless, their higher voltage tolerance and faster carrier drift suggest that, with increased charge collection, their timing performance could approach or even surpass that of Si LGADs. Furthermore, these results demonstrate the strong potential of 4H-SiC LGADs as a robustmore » platform for precision timing in future 4D tracking detectors, while also highlighting that signal charge is the dominant factor currently limiting their performance, indicating that further optimization of gain and drift structures will be essential for future development.« less

Low gain avalanche detectors (LGADs) offer high temporal resolution for high energy particle detection, which is critical for next generation experiments in hadron colliders. While silicon LGADs (Si-LGADs) have rapidly matured in the last decade, research into silicon carbide (SiC) LGADs has only recently begun. By accounting for fundamental differences in material properties and fabrication processes, we present a prototype device design and process flow for 4H-SiC LGADs with etch-based isolation. Critical steps of the process flow and their results are discussed, including plasma etching, passivation, and the formation of low resistivity contacts. Electrical characterization (I-V, C-V) shows sufficient depletionmore » of the device structure to demonstrate low-gain charge carrier multiplication.« less

4H-SiC Low Gain Avalanche Detectors (LGADs) have been fabricated and characterized. The devices employ a circular mesa design with low-resistivity contacts and an SiO₂ passivation layer. The I–V and C–V characteristics of the 4H-SiC LGADs are compared with complementary 4H-SiC PiN diodes to confirm a high breakdown voltage and low leakage current. Both LGADs and PiN diodes were irradiated with alpha particles from a $$^{210}_{84}$$Po source. The charge collected by each device was compared, and it was observed that low-gain charge carrier multiplication is achieved in the 4H-SiC LGAD.

Using $(2712.4\pm 14.3)\times {10}^6$ $\psi \left(3686\right)$ events collected with the BESIII detector at BEPCII, a partial wave analysis of the decay $\psi \left(3686\right)\to \varphi \eta {\eta }^{\prime }$ is performed with the covariant tensor approach. In addition to the established states $h_1(1900$ ) and $\varphi \left(2170\right)$ , an axial-vector state with a mass near $more »$ 2.3     GeV / c 2 is observed for the first time. Its mass and width are measured to be $2316\pm 9_{\mathrm{stat}}\pm 30_{\mathrm{syst}}\mathrm{MeV}/c^2$ and $89\pm 15_{\mathrm{stat}}\pm 26_{\mathrm{syst}}\mathrm{MeV}$ , respectively. The product branching fractions of $\mathcal{B}\left[\psi \right(3686)\to X(2300\left){\eta }^{\prime }\right]\mathcal{B}\left[X\right(2300)\to \varphi \eta ]$ and $\mathcal{B}\left[\psi \right(3686)\to X(2300\left)\eta \right]\mathcal{B}\left[X\right(2300)\to \varphi {\eta }^{\prime }]$ are determined to be $(4.8\pm {1.3}_{\mathrm{stat}}\pm {0.7}_{\mathrm{syst}})\times {10}^{-6}$ and $(2.2\pm {0.7}_{\mathrm{stat}}\pm {0.7}_{\mathrm{syst}})\times {10}^{-6}$ , respectively. The branching fraction $\mathcal{B}\left[\psi \right(3686)\to \varphi \eta {\eta }^{\prime }]$ is measured for the first time to be ( $3.14\pm 0.17_{\mathrm{stat}}\pm 0.24_{\mathrm{syst}})\times {10}^{-5}$ . The first uncertainties are statistical and the second are systematic. Published by the American Physical Society 2025« less

The design, fabrication, and demonstration of a novel Silicon Carbide Low Gain Avalanche Detector (4HSiC LGAD), exhibiting an ultra-fast time response and excellent time resolution, are reported. Here, the use of field plates is proposed to suppress the high electric field caused by the negative bevel-etched angle in 4H-SiC LGADs based on TCAD simulations. Experimental measurements confirm that the field plate significantly increases the breakdown voltage of the 4H-SiC LGADs. Gain and time resolution are measured by using the ultraviolet transient current technique (UV-TCT) showing that 4H-SiC LGADs possess excellent timing performance, with a time resolution better than 35 psmore » for the injected laser signal with single minimum ionizing particle (MIP) charges generation at room temperature. Additionally, the gain suppression effect in a 4H-SiC LGAD is observed for the first time.« less

Based on $(2712.4\pm 14.1)\times {10}^6$ $\psi \left(3686\right)$ decays collected with the BESIII detector, we have observed, for the first time, the hadronic decays of S- and P-wave charmonium states into $2\left({\pi }^{+}{\pi }^{-}\right)\eta$ via radiative transitions from $\psi \left(3686\right)$ . The branching fraction of the decay ${\eta }_c\left(1S\right)\to 2({\pi }^{+}{\pi }^{more »}$ − ) η has a significant dependence on the interference pattern between ${\eta }_c\left(1S\right)$ and non- ${\eta }_c\left(1S\right)$ processes. We measure it in both the destructive and constructive interference scenarios for the first time. The mass and width of the ${\eta }_c\left(1S\right)$ are measured to be $M=(2984.14\pm 0.13\pm 0.38)\mathrm{MeV}/c^2$ and $\mathrm{\Gamma }=(28.82\pm 0.11\pm 0.82)\mathrm{MeV}$ , respectively. Clear signals for the decays of the ${\chi }_{cJ}(J=0,1,2)$ and the ${\eta }_c\left(2S\right)$ to $2\left({\pi }^{+}{\pi }^{-}\right)\eta$ are also observed for the first time, and the corresponding branching fractions are measured. The ratio of the branching fractions between the ${\eta }_c\left(2S\right)$ and ${\eta }_c\left(1S\right)$ decays is significantly lower than the theoretical prediction, which might suggest different dynamics in their decays. Published by the American Physical Society 2025« less

One major degradation mechanism during long-term operation of solid oxide electrolysis cells (SOECs) is delamination of oxygen electrodes (OEs). The driving force for the electrode delamination could be the generated high inner oxygen pressure near the electrode-electrolyte interface during operation. However, the effects of transport properties and electrode thickness on the inner oxygen partial pressure are not well understood. Here a microstructure-based electrochemical model, which includes the conduction of electrons and oxygen ions coupled with Butler-Volmer-type chemical reactions at triple-phase-boundaries (TPBs), is employed to investigate the oxygen pressure in lanthanum strontium manganate (LSM)-based SOECs. The model is applied to bothmore » two-dimensional (2D) prototype microstructures and three-dimensional (3D) realistic microstructures, and the oxygen pressure is analyzed as a function of transport properties and electrode thickness under both potentiostatic and galvanostatic operations. The simulation results suggest strategies to suppress electrode delamination. The simulation results are compared to an analytical solution, and the discrepancies are attributed to the Butler-Volmer-type kinetics included in the microstructure-based model.« less

The inclusive cross sections of prompt $J/\psi$ and $\psi \left(3686\right)$ production are measured at center-of-mass energies from 3.808 to 4.951 GeV. The dataset used is $22{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected with the BESIII detector operating at the BEPCII storage ring. The results obtained are in agreement with the previous BESIII measurements of exclusive $J/\psi$ and $\psi \left(3686\right)$ production. The average values obtainedmore » for the cross sections measured in the center-of-mass energy ranges from 4.527 to 4.951 GeV for $J/\psi$ and from 4.843 to 4.951 GeV for $\psi \left(3686\right)$ , where the impact of known resonances is negligible, are $14.0\pm 1.7\pm 3.1\mathrm{pb}$ and $15.3\pm 3.0\mathrm{pb}$ , respectively. For $J/\psi$ , the first and the second uncertainties are statistical and systematic, respectively. For $\psi \left(3686\right)$ , the uncertainty is total. These values are useful for testing charmonium production models. Published by the American Physical Society 2025« less

We measure the Born cross section for the reaction 𝑒⁺⁢𝑒⁻→ 𝜂⁢ℎ_𝑐 from $$\sqrt{𝑠}$$ = 4.129 to 4.600 GeV using datasets collected by the BESIII detector running at the BEPCII collider. A resonant structure in the cross-section line shape near 4.200 GeV is observed with a statistical significance of 7⁢𝜎. The parameters of this resonance are measured to be 𝑀 = 4188.8 ± 4.7 ± 8.0 MeV/𝑐² and Γ = 49 ± 16 ± 19 MeV, where the first uncertainties are statistical and the second systematic.

Background Cerebral aneurysm is a high-risk cerebrovascular disease with a poor prognosis, potentially linked to multiple factors. This study aims to explore the association between mitochondrial-associated proteins and the risk of cerebral aneurysms using Mendelian randomization (MR) methods. Methods We used GWAS summary statistics from the IEU Open GWAS project for mitochondrial-associated proteins and from the Finnish database for cerebral aneurysms (uIA, aSAH). The association between mitochondrial-associated exposures and cerebral aneurysms was evaluated using MR-Egger, weighted mode, IVW, simple mode and weighted median methods. Reverse MR assessed reverse causal relationship, while sensitivity analyses examined heterogeneity and pleiotropy in the instrumentalmore » variables. Significant causal relationship with cerebral aneurysms were confirmed using FDR correction. Results Through MR analysis, we identified six mitochondrial proteins associated with an increased risk of aSAH: AIF1 (OR: 1.394, 95% CI: 1.109–1.752, p  = 0.0044), CCDC90B (OR: 1.318, 95% CI: 1.132–1.535, p  = 0.0004), TIM14 (OR: 1.272, 95% CI: 1.041–1.553, p  = 0.0186), NAGS (OR: 1.219, 95% CI: 1.008–1.475, p  = 0.041), tRNA PusA (OR: 1.311, 95% CI: 1.096–1.569, p  = 0.003), and MRM3 (OR: 1.097, 95% CI: 1.016–1.185, p  = 0.0175). Among these, CCDC90B, tRNA PusA, and AIF1 demonstrated a significant causal relationship with an increased risk of aSAH (FDR q  < 0.1). Three mitochondrial proteins were associated with an increased risk of uIA: CCDC90B (OR: 1.309, 95% CI: 1.05–1.632, p  = 0.0165), tRNA PusA (OR: 1.306, 95% CI: 1.007–1.694, p  = 0.0438), and MRM3 (OR: 1.13, 95% CI: 1.012–1.263, p  = 0.0303). In the reverse MR study, only one mitochondrial protein, TIM14 (OR: 1.087, 95% CI: 1.004–1.177, p  = 0.04), showed a causal relationship with aSAH. Sensitivity analysis did not reveal heterogeneity or pleiotropy. The results suggest that CCDC90B, tRNA PusA, and MRM3 may be common risk factors for cerebral aneurysms (ruptured and unruptured), while AIF1 and NAGS are specifically associated with an increased risk of aSAH, unrelated to uIA. TIM14 may interact with aSAH. Conclusion Our findings confirm a causal relationship between mitochondrial-associated proteins and cerebral aneurysms, offering new insights for future research into the pathogenesis and treatment of this condition.« less