— The review presents the experiments performed with the KEDR detector at the e^ + e^ - collider VEPP-4M in the energy range of √(s) = 1.84–3.88 GeV. The cross section of e^ + e^ - annihilation to hadrons was measured at 22 points of this range and the search for narrow resonances was conducted below 3.1 GeV. The masses of J / . -0emψ and ψ (2S) mesons were measured with a record accuracy better than 3 ×10^ - 6 ; their partial and total widths were determined. Measurements of the tau lepton mass and masses of charged and neutral D mesons were performed with high precision. The measurements of the ψ (3770) parameters are discussed, and attention is drawn to some inconsistency of the procedure employed by the Particle Data Group for determining its parameters.

We present the study of the decay J/ψ → ρπ . The results are based on of 5.2 million J/ψ events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured to be ℬ ( J/ψ → ρπ ) = (2 . 072 ± 0 . 017 ± 0 . 062) ∙ 10 − 2 and ℬ ( J/ψ → π + π − π 0 ) = (1 . 878 ± 0 . 013 ± 0 . 051) ∙ 10 − 2 , where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.

Using the 1.32 pb^-1 statistics collected at the J/ψ peak with the KEDR detector at the VEPP-4M e^+e^- collider, we measured the branching fractions of J/ψ meson decays to the final states 2( π ^+π ^-)π ^0 , K^+K^-π ^+π ^-π ^0 , 2( π ^+π ^-) and K^+K^-π ^+π ^- . The results obtained for the decays J/ψ→ 2( π ^+π ^-)π ^0 , J/ψ→ K^+K^-π ^+π ^-π ^0 contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.

Abstract Using the 1.32 $$\hbox {pb}^{-1}$$ pb - 1 statistics collected at the $$J/\psi $$ J / ψ peak with the KEDR detector at the VEPP-4M $$e^{+}e^{-\, }$$ e + e - collider, we measured the branching fractions of $$J/\psi $$ J / ψ meson decays to the final states 2( $$\pi ^{+}\pi ^{-})\pi ^{0}$$ π + π - ) π 0 , $$K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$ K + K - π + π - π 0 , 2( $$\pi ^{+}\pi ^{-})$$ π + π - ) and $$K^{+}K^{-}\pi ^{+}\pi ^{-}$$ K + K - π + π - . The results obtained for the decays $$J/\psi \rightarrow $$ J / ψ → 2( $$\pi ^{+}\pi ^{-})\pi ^{0}$$ π + π - ) π 0 , $$J/\psi \rightarrow K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$ J / ψ → K + K - π + π - π 0 contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.

Using the 1.32 pb(-1) statistics collected at the J/psi peak with the KEDR detector at the VEPP-4M e(+)e(-) collider, we measured the branching fractions of J/psi meson decays to the final states 2(pi(+)pi(-))pi(0), K+K- pi(+)pi(-)pi(0), 2(pi(+)pi(-)) and K+K- pi(+)pi(-). The results obtained for the decays J/psi -> 2(pi(+)pi(-))pi(0), J/psi -> K+K- pi(+)pi(-)pi(0) contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.

Using the 1.32 pb^-1 statistics collected at the J/ψ peak with the KEDR detector at the VEPP-4M e^+e^- collider, we measured the branching fractions of J/ψ meson decays to the final states 2( π ^+π ^-)π ^0 , K^+K^-π ^+π ^-π ^0 , 2( π ^+π ^-) and K^+K^-π ^+π ^- . The results obtained for the decays J/ψ→ 2( π ^+π ^-)π ^0 , J/ψ→ K^+K^-π ^+π ^-π ^0 contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.

We review the recent results obtained by the KEDR experiment in the charmonium energy range. They include the measurements of J/psi meson total and partial widths and exclusive branching fractions, study of D+ and D-0 meson masses and R between 1.8 and 7.0 GeV.

In the framework of the large hadron collider (LHC) upgrade project, new materials are proposed for the vacuum. Amorphous carbon deposited onto the vacuum-chamber wall is examined as a coating with a low secondary electron emission rate for superconducting systems designed to upgrade the LHC, i.e., to increase the luminosity of the machine (HL-LHC). Since protons will generate synchrotron radiation with a critical energy of ~10 eV and a flux of 1016 photon m–1 s–1, it is important to study the effect of photons on a surface covered with amorphous carbon at room and cryogenic temperatures. The construction and parameters of the setup on the new synchrotron beamline of the VEPP-2000 booster are described. The first results of measuring the photodesorption coefficient are also presented.

The electronic width of the J/psi meson and its product by the branching fractions of J/psi meson decay to hadrons and electrons measured with the KEDR detector at the VEPP-4M e(+)e(-) collider have been reported in ref. [1].

The electronic width of the J / ψ meson and its product by the branching fractions of J / ψ meson decay to hadrons and electrons measured with the KEDR detector at the VEPP-4M e + e − collider have been reported in ref. [1].

The gettering characteristics of Ti–Zr–Al getter pumps with internal and external heaters have been measured for Н2 and CO. The results are compared to the measured similar characteristics of an NEX‑Torr D 100-05 combined pump from SAES Getters and a titanium sublimation film at temperatures of 300 and 77 K.

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 Ruds 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.

High or ultrahigh vacuum must be provided in new accelerating facilities with wide-aperture vacuum systems, such as FAIR (Darmstadt, Germany) and NICA (Dubna, Russia). One of the problems encountered while designing such systems is the selection of vacuum-tight connections and gasket types. Theuse of an ISO-K flange with a spring metallic C-shaped seal is considered the most promising possible variant of a detachable vacuum joint in comparison with the COF, ConFlat, or flat VATSeal flanges.

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 we measured the values of $R_{text{uds}}$ and $R$ at nine points of the center-of-mass energy 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 $1.9%$.

The product of the electronic width of the ψ(2S) meson and the branching fraction of its decay to the muon pair was measured in the e+e−→ψ(2S)→μ+μ− 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:Γee×Bμμ=19.3±0.3±0.5eV. Adding the previous KEDR results on hadronic and leptonic channels, the values of the ψ(2S) electronic width were obtained under two assumptions: either with the assumption of lepton universalityΓee=2.279±0.015±0.042keV or without it, summing up hadronic and three independent leptonic channelsΓee=2.282±0.015±0.042keV.