Precise measurement of RudsR_{\text{uds}} and RR between 1.84 and 3.72 GeV at the KEDR detector

The present work continues a series of the KEDR measurements of the $R$ value that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data with our previous results in this energy range we measured the values of $R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than $2.6\%$ at most of energy points with a systematic uncertainty of about $1.9\%$. Together with the previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision $R$ measurement near the charmonium production threshold.Comment: arXiv admin note: text overlap with arXiv:1610.02827 and substantial text overlap with arXiv:1510.0266

The beam energy measurement system for the Beijing electron-positron collider

The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron and positron beam energy determination is estimated as 2 \cdot 10^{-5}. The relative uncertainty of the beam's energy spread is about 6 %

Measurement of Γee×Bμμ\Gamma_{ee}\times\mathcal{B}_{\mu\mu} for ψ(2S)\psi(2S) meson

The product of the electronic width of the $\psi(2S)$ meson and the branching fraction of its decay to the muon pair was measured in the $e^{+}e^{-} \to \psi(2S) \to \mu^{+}\mu^{-}$ process using nine data sets corresponding to an integrated luminosity of about 6.5 pb$^{-1}$ collected with the KEDR detector at the VEPP-4M electron-positron collider: $$\Gamma_{ee}\times\mathcal{B}_{\mu\mu} = 19.3 \pm 0.3 \pm 0.5 ~\text{eV}.$$ Adding the previous KEDR results on hadronic and leptonic channels, the values of the $\psi(2S)$ electronic width were obtained under two assumptions: either with the assumption of lepton universality $$\Gamma_{ee} = 2.279 \pm 0.015 \pm 0.042 ~\text{keV}$$ or without it, summing up hadronic and three independent leptonic channels: \[ \Gamma_{ee} = 2.282 \pm 0.015 \pm 0.042 ~\text{keV}. \

Measurement of the branching fraction of J/ψ→ρπJ/\psi\rightarrow\rho\pi at KEDR

We present the study of the decay $J/\psi \rightarrow \rho \pi$. The results are based on of 5.2 million $J/\psi$ events collected by the KEDR detector at VEPP-4M collider. The branching fraction is measured to be $\mathcal{B}(J/\psi\rightarrow\rho\pi) = \big(2.072\pm 0.017 \pm 0.056 \big)\cdot 10^{-2}$ where the first uncertainty is statistical, the second one is systematic. This is the most precise single measurement of this quantity at the moment

Cross-platform mobile software development : technology overview and a practical example

The vast diversity of portable devices has increased the need for an easy and unified approach to build mobile software. The purpose of this work is to give an overview of technologies widely used to deliver cross-platform software solutions. This was achieved by studying two of the most common cross-platform frameworks – Xamarin.Forms and Cordova. The first part of the work introduces the problem of mobile software development. The second part describes the underlying technology of the cross-platform solutions and compares them to the native application development in terms of benefits and drawbacks. The third part provides a practical example of building an app using the two cross-platform solutions, demonstrating the workflow of development and a toolset used

SIMULATION OF ACOUSTIC EMISSIONS FOR REAL CORE SAMPLES

The paper presents the results of laboratory experiments and numerical modeling for solving the problem of acoustic emission event recovery. The equations of the dynamic theory of elasticity in the polar coordinate system were used as a mathematical model. The simulation results made it possible to evaluate a number of basic characteristics for the configuration of a multichannel data acquisition system, the frequency of the AE signals, to determine the required number of recording channels and the position of the sensors in the core., The 3D modeling is planned in the near future in order to develop a mathematical method for reconstructing the AE events from the records of a real physical experiment.</jats:p