[en] The structure and working principle of Micromegas (MICRO Mesh Gaseous Structure) is discussed. Some radiation sources of α and X rays are used to test this detector. The optimized electric-field intensity of the conversion gap is obtained. The transmission of electrons and the uniformity of the amplification gap are also presented. The energy resolution of the 5.9 keV peak is better than 27%. (authors)

[en] In this paper we report our simulation work on the electron transparency and the ion feedback in Micromegas detector with woven wire meshes. A simplified 3D model is build to generate electric field in the detector and to perform Monte Carlo simulation of electron and ion drift behaviors. Influence of the gas mixture to the electron transparency and ion feedback is discussed and explained. Comparison of electron transparency and ion feedback with meshes which have same optical transparency and different wire diameter show different variation trends. This indicates the important role the hole size has played in the determination of the two parameters discussed in the paper. This work might be helpful to the optimization of the detector design. (authors)

[en] Micromegas (MICRO MEsh GAseous Structure) is a position-sensitive gaseous detector. It is widely used in particle physics. We present the results of full 3D Monte Carlo simulations of Micromegas performance, taking into account all the processes from the primary ionization, the electron collection efficiency, and the gain to the signal formation. The simulation results are in good agreement with experimental data. (authors)

[en] Non-radial p modes and g modes appear simultaneously in red giant stars. Their frequencies have different variation rates, causing their frequencies to become close during stellar evolution so that avoided crossings appear. The separation between regions where acoustic waves and gravity waves propagate for l = 1, 2 and 3 is different, which results in the coupling efficiency also being different. We present the results of numerical computations of the models we study. We find that the two kinds of modes for l = 2 and 3 need to be closer in frequency in order for a complete exchange to occur, compared to the case for modes with l = 1. Their scaled oscillation frequencies also present better regularity with evolution than modes with l = 1. In order to study the effect of the avoided crossings in detail, we set the mode which has the smallest mode inertia to be the p mode. We plot the two kinds of modes for l = 1, 2 and 3 in frequency and period échelle diagrams and find modes of l = 2 and 3 fit the two relations better; they are more equally spaced in frequency and period than modes with l = 1. Under careful observation of the two kinds of échelle diagrams for l = 2 and 3, we still find that some p modes shift a little from being equally spaced in frequency and some g modes, which are close to those p modes in period, shift a little from being equally spaced in period. Then, we study the relation between the deviation from period being equally spaced and the mode inertia of g modes for different l. The g modes of l = 1 with a period closer to the p mode have less inertia and the deviation is bigger in the period échelle diagram. Their deviation is also obvious. However g modes of l = 2 and 3 shift a little or have almost no deviation from being equally spaced in period, even though some of them may have strong coupling and close mode inertia like in the p modes. So, we suggest a possible method for measuring period spacing of g modes precisely using mixed g modes with l = 2 and 3 that have fewer observed mixed g modes than for l = 1. (research papers)

[en] In this paper we report the results of Micromegas prototypes constructed by attaching micromesh to an anode using thermo-bond films. The excellent metal attaching ability and good dielectical property of this kind of film make it a promising material to be used as avalanche gap spacers. Several prototypes are successfully made. The electron transmission properties are first studied and then the gas gain is measured in argon-isobutane mixtures. The maximum gain of more than 10⁴ is easily obtained. The energy resolutions for ⁵⁵Fe 5.9 keV K_α ray can be better than 20% over one magnitude in gain for different operational gas mixtures and the best energy resolution of 13.7% (FWHM) can be achieved with the gas mixture of 94% argon concentration. The preliminary test results of the prototypes with sensitive area of 45 mm x 45 mm without internal support show good uniformity across the sensitive area. (authors)

[en] Objective: To investigate the clinical significance of radiotherapy for stage IV esophageal cancer. Methods: Clinical data of 133 stage IV esophageal cancer patients admitted to our hospital from 2012 to 2018 were retrospectively analyzed. All patients were assigned into the radiochemotherapy (n = 89)and chemotherapy groups (n = 44). The survival analysis was performed by Kaplan-Meier method. The multivariate prognostic analysis was conducted by Cox's regression model. Results: The 1-, 2- and 3- year overall survival rates of the entire cohort were 53.5%, 20.4% and 13.6% respectively. Cox's regression analysis showed that gender, ECOG score, number of distant metastases, and whether the primary lesions received radiotherapy were the independent prognostic factors (all P < 0.05). The 1-, 2- and 3- year survival rates in the radiochemotherapy group were 61%, 29% and 19%, and 40%, 4%, 0% in the chemotherapy group, respectively. In the radiochemotherapy group, the progression-free survival (PFS) and local progression-free survival (LPFS) were 8 months and 12.6 months, significantly longer compared with 4.7 months and 5.3 months in the chemotherapy group (both P < 0.05). The OS of patients receiving dose > 50 Gy and ≤ 50 Gy was 14.3 months and 8.2 months (P < 0.05), 8.6 months and 2.8 months for the PFS (P < 0.05), and 15.2 months and 4.7 months for the LRFS (P < 0.05), respectively. The number of distant metastases and the clinical efficacy for primary lesions were the independent prognostic factors in the radiochemotherapy group (both P < 0.05). Conclusion: Radiotherapy can improve the clinical prognosis of patients with stage IV esophageal cancer. (authors)

[en] Based on regularities in rotational splitting, we seek possible multiplets for the observed frequencies of CoRoT 102749568. There are 21 sets of multiplets identified, including four sets of multiplets with l = 1, nine sets of multiplets with l = 2, and eight sets of multiplets with l = 3. In particular, there are three complete triplets (f₁₀, f₁₂, f₁₄), (f₃₁, f₃₄, f₃₅), and (f₄₁, f₄₃, f₄₄). The rotational period of CoRoT 102749568 is estimated to be ${1.34}_{-<!--\; ???\; -->0.05}^{+0.04}$ days. When doing model fittings, three l = 1 modes (f₁₂, f₃₄, and f₄₃) and the radial first overtone f₁₃ are used. Our results shows that the three nonradial modes (f₁₂, f₃₄, and f₄₃) are mixed modes, which mainly provide constraints on the helium core. The radial first overtone f₁₃ mainly provides constraint on the stellar envelope. Hence the size of the helium core of CoRoT 102749568 is determined to be $M_{\mathrm{H}\mathrm{e}}$ = 0.148 ± 0.003 M_⊙ and $R_{\mathrm{H}\mathrm{e}}$ = 0.0581 ± 0.0007 R_⊙. The fundamental parameters of CoRoT 102749568 are determined to be M = 1.54 ± 0.03 M_⊙, $Z=0.006$, $f_{\mathrm{o}\mathrm{v}}=0.004\pm <!--\; ??\; -->0.002$, $\mathrm{l}\mathrm{o}\mathrm{g}g=3.696\pm <!--\; ??\; -->0.003$, $T_{\mathrm{e}\mathrm{f}\mathrm{f}}=6886\pm <!--\; ??\; -->70$ K, R = 2.916 ± 0.039 R_⊙, and L = 17.12 ± 1.13 L_⊙.

[en] Highlights: • Compatible configuration strategy for tangential oxy-burners is firstly proposed. • Momentum ratio criterion for tangentially fired oxy-combustion is illustrated. • Temperature deviation is reduced by using opposing tangential stream technology. • Temperature deviation and CO level are decreased by approximately 65% and 90%. The configurations of burner streams under oxy-fuel combustion are highly affected by its increased initial oxygen level. In this study, an air combustion and oxy-fuel combustion compatible configuration strategy for burner streams is proposed for a 200 MW_e tangentially fired boiler, by aid of numerical simulation. Firstly, to achieve a momentum of primary and secondary streams that is similar to that of air combustion, the tertiary stream is switched-off in oxy-fuel combustion. In addition, the opposing tangential primary stream technology is suggested to reduce the gas temperature deviation in the upper furnace, which affects the quality of the steam and the safe operation of the boiler. For the present study, the appropriate opposing tangential angle is 5°–7° relative to the original primary stream design, and the ratio of opposing tangential momentum flow moment should be controlled at the low limit of 0.8 to decrease gas temperature deviation. To achieve a supported flame by the secondary stream, the momentum of the bottom secondary stream in oxy-fuel combustion should not be less than that in air combustion. The study illustrates for the first time that, the key design features of tangentially fired burners under oxy-fuel combustion. Although there are significant changes in the oxidant volume, oxidant composition, and chemical reaction under oxy-fuel combustion conditions, the design criteria of oxy-fuel tangentially fired boiler, in terms of momentum of the primary stream, momentum of the bottom secondary stream, and momentum ratio and momentum flow moment ratio of the secondary stream to primary stream, are consistent with those under air combustion.

[en] Multi-gap Resistive Plate Chambers (MRPCs) were selected to construct the barrel Time of Flight (TOF) detector for the STAR experiments. Its mass production started in 2006. The production procedure and related quality control (QC) are described. A summary of the MRPC production status (2006-2008) and the test results with cosmic rays is given. With strict QC throughout the production process, over 95% of the constructed MRPC modules meet the criteria required by STAR experiments.

[en] The energy disorder originating from quantum dot (QD) size and relevant solid film inhomogeneity is detrimental to the charge transport and efficiency of QD based solar cells. The emergence of halide perovskite QDs (PQDs) have attracted great attention as promising absorbers in QD photovoltaics. However, it is currently difficult in preparing structural uniform PQD film with homogenous energetic landscape, which is essential for highly reproducible and efficient solar cells. Herein, assisted by a bidentate ligand 2,5-thiophenedicarboxylic acid, a facile solution phase anchoring (SPA) strategy is first reported for design and preparation of all-inorganic CsPbI${}_3$ PQD film with reduced structure and energy disorder. The SPA can enhance PQD dispersion as well as dot-to-dot interaction, which is beneficial for fabricating high-quality PQD arrays and photovoltaic devices. The engineered CsPbI${}_3$ PQD solar cell exhibits enhanced reproducibility, and higher open-circuit voltage together with a champion efficiency of 16.14%, which is among the highest report to date. These results are believed to provide design principle of uniform PQDs for high-performance optoelectronic application. (© 2023 Wiley‐VCH GmbH)