Preliminary results of measurements by automated probes Vega 1 and 2 or particle concentration in clouds of Venus at heights 47-63 KM

Results of the preliminary processing of the Vega 1 and 2 descender data on the cloud layer structure of the Venusian atmosphere are discussed. A photoelectric counter for aerosol particles is described together with its optical and pneumatic circuits and operation algorithm. Vertical profiles of concentrations of particles with a diameter of 0.4 microns agree quantitatively with the Pioneer-Venus and Venera 9 and 10 data. Concentrations of these particles are: in the B layer, up to 190/cu cm; in the C layer, up to 10/cu cm; and in the D layer, up to 130/cu cm. Layers have sharp boundaries with a significant vertical heterogeneity of the aerosol concentration field inside them

Detector for imaging of explosions: present status and future prospects with higher energy X-rays

The detector for imaging of explosions (DIMEX) is in operation at the synchrotron radiation (SR) beam-line at VEPP-3 electron ring at Budker INP since 2002. DIMEX is based on one-coordinate gas ionization chamber filled with Xe-CO2(3:1) mixture at 7atm, and active Frisch-grid made of Gas Electron Multiplier (GEM). The detector has spatial resolution of ~0.2mm and dynamic range of ~100 that allows to realize the precision of signal measurement at a percent level. The frame rate can be tuned up to 8 MHz (125 ns per image) and up to 32 images can be stored in one shot. At present DIMEX is used with the X-ray beam from 2T wiggler that has ~20 keV average energy. Future possibility to install similar detector at the SR beam-line at VEPP-4 electron ring is discussed.Comment: 14 pages, 15 figures. Submitted to JINS

Dipyrazolodioxadiazocines as Easily Storable and “Ready to Use” Precursors for in Situ Generation of Enolate-Iminium 1,4-Dipoles: an Atom-Economical Approach Topyrazolo[5,1-d][1,3,5]Dioxazines

The work was supported by Russian Science Foundation, project № 19-13-00290

Detector for imaging of explosions: present status and future prospects with higher energy X-rays

The detector for imaging of explosions (DIMEX) is in operation at the synchrotron radiation (SR) beam-line at VEPP-3 electron ring at Budker INP since 2002. DIMEX is based on one-coordinate gas ionization chamber filled with Xe-CO2(3:1) mixture at 7atm, and active Frisch-grid made of Gas Electron Multiplier (GEM). The detector has spatial resolution of ~0.2mm and dynamic range of ~100 that allows to realize the precision of signal measurement at a percent level. The frame rate can be tuned up to 8 MHz (125 ns per image) and up to 32 images can be stored in one shot. At present DIMEX is used with the X-ray beam from 2T wiggler that has ~20 keV average energy. Future possibility to install similar detector at the SR beam-line at VEPP-4 electron ring is discussed.Comment: 14 pages, 15 figures. Submitted to JINS

CYCLOADDITION OF 1,4-CNCO DIPOLES GENERATED FROM DIPYRAZOLODIOXADIAZOCINES

This work was supported by the Russian Science Foundation, project # 19-13-00290

Regiodivergent dipolar cycloaddition based on pyrrole-2,3-diones

It was previously demonstrated, that thermal decarbonylation of N-substituted 2,3-dihydro-2,3-pyrroldiones afforded imidoylketenes, whose chemical behavior largely depends on the nature of substituents at N-1. It was discovered that N-(diphenylenamino)pyrrolediones experienced facile CO-extrusion at elevated temperatures and the resulting a zwitterionic dihydropyrazolone species, which can be represented by enolate-iminium 1,4-dipole resonance form. In the absence of dipolarophiles, the products of [4+4]-cyclodimerization – bis(pyrazolo)dioxadiazocines – were formed in high yields. To this end, we generated the ketenes in the presence of alkyl vinyl ethers, aldehydes, ketenes, nitriles and isocyanides targeting products of dipolar cycloadditions. We further elaborated on the development of various synthetic schemes involving cycloaddition of these unusual 1,4-dipoles. Dipyrazolodioxadiazocines are shelf-stable "ready-to-use" precursors for an in situ generation of enolate-iminium 1,4-dipoles.This work was supported by the Russian Science Foundation, project № 19-13-00290

Measurement of J/ψ→γηcJ/\psi\to\gamma\eta_{\rm c} decay rate and ηc\eta_{\rm c} parameters at KEDR

Using the inclusive photon spectrum based on a data sample collected at the $J/\psi$ peak with the KEDR detector at the VEPP-4M $e^+e^-$ collider, we measured the rate of the radiative decay $J/\psi\to\gamma\eta_{\rm c}$ as well as $\eta_{\rm c}$ mass and width. Taking into account an asymmetric photon lineshape we obtained $\Gamma^0_{\gamma\eta_{\rm c}}=2.98\pm0.18 \phantom{|}^{+0.15}_{-0.33}$ keV, $M_{\eta_{\rm c}} = 2983.5 \pm 1.4 \phantom{|}^{+1.6}_{-3.6}$ MeV/$c^2$, $\Gamma_{\eta_{\rm c}} = 27.2 \pm 3.1 \phantom{|}^{+5.4}_{-2.6}$ MeV.Comment: 6 pages, 3 figure