arXiv subjects

A. A. Krasnov

Publications and source records attributed to A. A. Krasnov.

11 recordsLinked to original sources

arXiv2025

Low-impedance stripline kicker for the transverse instability suppression system of the synchrotron radiation facility "SKIF" light source

Construction of the new fourth generation synchrotron radiation facility (SRF) "SKIF" near Novosibirsk is nearing completion. "SKIF" uniqueness is ultra-low 75 pm natural emittance at 400 mA beam current and 3 GeV beam energy. Collective effects (beam interaction with the vacuum chamber) are the main obstacles of achieving such emittance and beam current. To suppress these effects the storage ring will be equipped with a bunch-by-bunch feedback system. Important components of the feedback system are a stripline (fast) kicker and a beam position monitor. The paper describes design of the low-impedance stripline kicker for SRF "SKIF" storage ring, optimized for the manufacturing and for the uniformity of the imparted transverse kick. The kicker qualities such as S-parameters, imparted transverse momentum, transfer and beam impedances are presented. The chosen length of the stripline kicker allows its use as a beam position monitor.

physics.acc-ph↗

arXiv2025

The branching fraction measurements of $J/ψ$ decay into $ρη$ and $ϕη$ final states

We present measurements of the branching fractions for the $J/ψ$ meson decays into the $ρη$ and $ϕη$ final states, based on data collected with the KEDR detector at the VEPP-4M collider. The data set consisted of 4.93 million $J/ψ$ events. The resulting branching fractions are: - $\mathcal{B}(J/ψ\to ρη) = (2.04 \pm 0.58 \pm 0.39)\times 10^{-4}$, - $\mathcal{B}(J/ψ\to ϕη) = (7.82 \pm 1.17 \pm 0.58) \times 10^{-4}$, where the first uncertainty is statistical and the second one is systematic. In the study of the $ρη$ decay, the dynamics of $J/ψ\toπ^+π^-η$ is analyzed. The hints from contributions of $ρ(1450)η$ and $a^{\pm}_2π^{\mp}$ intermediate states are observed. Additional measured branching fractions in the model that includes $ρ(1450)η$ and $a^{\pm}_2π^{\mp}$ are: - $\mathcal{B}(J/ψ\to π^+π^-η) = (4.73 \pm 0.49 \pm 1.17)\times10^{-4}$, - $\mathcal{B}(J/ψ\to (a_2^+π^- + a_2^- π^+)) = (1.05\pm 0.37 \pm 0.34)\times 10^{-3}$, - $\mathcal{B}(J/ψ\to ρ(1450)η\to π^+π^-η) < 1.51 \times 10^{-4}$, at a confidence level of 90\%. All results are consistent with previous studies.

hep-ex↗

arXiv2025

New measurement of D0 and D+ meson masses with the KEDR detector

Using the 4.9 pb$^{-1}$ statistics collected at the peak of the $ψ(3770)$ resonance with the KEDR detector at the VEPP-4M electron-positron collider, we measured the masses of the neutral and charged D mesons: $M_{D^0} = 1865.100 \pm 0.210 (stat) \pm 0.046 (syst) MeV,$ and $M_{D^+} = 1869.560 \pm 0.288 (stat) \pm 0.109 (syst) MeV$.

hep-ex↗

arXiv2023

Measurement of the branching fraction of $J/ψ\rightarrowρπ$ at KEDR

We present the study of the decay $J/ψ\rightarrow ρπ$. 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 $\B(J/ψ\rightarrow ρπ) = \big(2.072\pm 0.017 \pm 0.062 \big)\cdot 10^{-2}$ and $\B(J/ψ\rightarrow π^+π^-π^0) = \big(1.878 \pm 0.013 \pm 0.051 \big)\cdot 10^{-2}$, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.

hep-ex↗

arXiv2018

Precise measurement of $R_{\text{uds}}$ and $R$ 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.

hep-ex↗

arXiv2018

Measurement of $Γ_{ee}\times\mathcal{B}_{μμ}$ for $ψ(2S)$ meson

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 $e^{+}e^{-} \to ψ(2S) \to μ^{+}μ^{-}$ 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: \[ Γ_{ee}\times\mathcal{B}_{μμ} = 19.3 \pm 0.3 \pm 0.5 ~\text{eV}. \] 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 universality \[ Γ_{ee} = 2.279 \pm 0.015 \pm 0.042 ~\text{keV} \] or without it, summing up hadronic and three independent leptonic channels: \[ Γ_{ee} = 2.282 \pm 0.015 \pm 0.042 ~\text{keV}. \]

hep-ex↗

arXiv2015

Upgrade of Beam Energy Measurement System at BEPC-II

The beam energy measurement system is of great importance and profit for both BEPC-II accelerator and BES-III detector. The system is based on measuring the energies of Compton back-scattered photons. Many advanced techniques and precise instruments are employed to realize the highly accurate measurement of positron/electron beam energy. During five year's running period, in order to meet the requirement of data taking and improve the capacity of measurement itself, the upgradation of system is continued, which involve the component reformation of laser and optics subsystem, replacement of view-port of the laser to vacuum insertion subsystem, the purchase of electric cooling system for high purity germanium detector, and the improvement of data acquisition and processing subsystem. The upgrading of system guarantees the smooth and efficient measuring of beam energy at BEPC-II and accommodates the accurate offline energy values for further physics analysis at BES-III.

physics.ins-det↗

arXiv2015

The system for delivery of IR laser radiaton into high vacuum

The system for insertion of a laser beam into the vacuum chamber of high-energy storage ring is described. The main part of the system is the high-vacuum viewport for the IR radiation, based on ZnSe or GaAs crystals. The design of the viewports is presented.

physics.acc-ph↗

arXiv2013

A system of beam energy measurement based on the Compton backscattered laser photons for the VEPP-2000 electron-positron collider

The beam energy measurement system for the VEPP-2000 electron-positron collider is described. The method of Compton backscattering of $CO$ laser photons on the electron beam is used. The relative systematic uncertainty of the beam energy determination is estimated as 6\cdot10^{-5}. It was obtained through comparison of the results of the beam energy measurements using the Compton backscattering and resonance depolarization methods.

physics.acc-ph↗

arXiv2013

Installation for SEE observation in the presence of magnetic field

The installation provides direct measurements of secondary emission yield and secondary electron velocity/energy distribution in the presence of magnetic field. The measurement system is designed to be installed into superconducting solenoid with maximum field of 10T. At present time the installation under commissioning at room temperature. The structure and performance capabilities of the setup are described, first experimental results are presented.

physics.acc-ph↗

arXiv2011

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 %.

physics.acc-ph↗