Олег Мешков | Novosibirsk State University (original) (raw)

Papers by Олег Мешков

The VEPP-4M electron-positron collider is now operating with the KEDR detector for high-energy ph... more The VEPP-4M electron-positron collider is now operating with the KEDR detector for high-energy physics experiments in the 1.5−2.0 GeV beam energy range. Parallel with these experiments, the VEPP-4M scientific team carries out a number of accelerator physics investigations. A new registration system for the Touschek polarimeter has been put into operation. A new NMRbased system for suppression of the guide field ripples has been developed. The counting rate of the Touschek particles has been measured as a function of the beam energy in the range from 1.85 to 4 GeV. The measurement results can be claimed at the future super B and C-Tau factories. For simultaneous measurement of the transverse beam position and inclination angle an X-ray multipinhole camera has been designed, manufactured and installed at the VEPP-4M. To suppress the longitudinal instability caused by high-order modes of the RF cavities, a feedback system has been developed.

arXiv (Cornell University), Nov 17, 2001

Physics of Particles and Nuclei Letters, 2014

The VEPP-4 accelerator-accumulator complex is designed for carrying out experiments with collidin... more The VEPP-4 accelerator-accumulator complex is designed for carrying out experiments with colliding electron-positron beams with the energy in the range of from 1 to 5 GeV using a VEPP-4M collider equipped with the KEDR magnetic detector. Experiments in the field of high-energy physics (HEP) using the complex in its present state have been being carried out since 2002. Science programs other than HEP programs are carried out in the VEPP-4, including experiments with synchrotron-radiation (SR) beams and studies on nuclear physics with an internal gas target, on verification of the CPT invariance, on accelerator physics, etc. The status of the complex, main results, methods used, new approaches, and long-term plans have been described.

Set of diagnostics of booster of NSLS-II includes 6 fluorescent screens (flags) and 2 synchrotron... more Set of diagnostics of booster of NSLS-II includes 6 fluorescent screens (flags) and 2 synchrotron light monitors (SLM). These diagnostics were applied during booster commissioning for closing of the beam turn and measurement of beam dimensions. They are also useful tool in case of malfunction elimination. We describe the experience obtained with several types of diagnostics during commissioning of the booster of NSLS-II. The information that was useful for commissioning as well as advantages and disadvantages of each diagnostics is discussed as well as the details of calibration and design of the devices are discussed. FLUORESCENT SCREENS Six fluorescent screens (beam flags) were applied for booster commissioning and troubleshooting. Fluorescent screens with their optics and cameras were used to measure transverse beam profile and position in single-pass mode. A beam image is registered by a CCD camera GC1290. The thickness of the Cerium-doped Yttrium Aluminum Garnet (YAG:Ce) plate ...

For the NSLS-II third generation light source, a full-energy Booster ring has been designed and p... more For the NSLS-II third generation light source, a full-energy Booster ring has been designed and produced by Budker Institute of Nuclear Physics. For the Booster commissioning and operation, following beam diagnostic instruments have been designed and manufactured: 6 beam flags, 36 electrostatic pickups with BPM receivers, 2 synchrotron light monitors (SLMs), 1 DC current transformer, 1 fast current transformer, Tune Measurement System (TMS) including 2 strip-line assemblies. All the equipment has been installed in the Booster ring and Injector Service Area. Control software of the beam diagnostic devices has been developed and incorporated into the NSLS-II control system using the EPICS environment. A number of high-level applications has been developed using Control System Studio and Python. The Integrated Testing and the System Level Testing have been performed. Current status of the Booster beam diagnostic instrumentation is reviewed.

Nuclear and Particle Physics Proceedings, 2015

The KEDR collaboration has taken data for R measurements at energies 3.1–3.7 GeV. Preliminary res... more The KEDR collaboration has taken data for R measurements at energies 3.1–3.7 GeV. Preliminary results from the analysis of these data are presented.

$Research paper thumbnail of Measurement of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>J</mi><mi mathvariant="normal">/</mi><mi>ψ</mi><mo>→</mo><mi>γ</mi><msub><mi>η</mi><mi mathvariant="normal">c</mi></msub></mrow><annotation encoding="application/x-tex">J/ψ\toγη_{\rm c}</annotation></semantics></math>J/ψ→γηc decay rate and <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mi>η</mi><mi mathvariant="normal">c</mi></msub></mrow><annotation encoding="application/x-tex">η_{\rm c}</annotation></semantics></math>ηc parameters at KEDR$

Physics Letters B, 2012

A high-precision determination of the main parameters of the ψ(2S) resonance has been performed w... more A high-precision determination of the main parameters of the ψ(2S) resonance has been performed with the KEDR detector at the VEPP-4M e + e − collider in three scans of the ψ(2S)-ψ(3770) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the ψ(2S) we obtained the mass value M = 3686.114 ± 0.007 ± 0.011 +0.002 −0.012 MeV and the product of the electron partial width by the branching fraction into hadrons Γ ee × B h = 2.233 ± 0.015 ± 0.037 ± 0.020 keV. The third error quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e + e − annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments. Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the ψ(2S): Γ ee = 2.282 ± 0.015 ± 0.038 ± 0.021 keV, Γ = 296 ± 2 ± 8 ± 3 keV. These results are consistent with and more than two times more precise than any of the previous experiments.

Physics Letters B, 2010

The masses of the neutral and charged D mesons have been measured with the KEDR detector at the V... more The masses of the neutral and charged D mesons have been measured with the KEDR detector at the VEPP-4M electron-positron collider:

arXiv preprint arXiv:1110.0328, Oct 3, 2011

Abstract: We report a new precise determination of the leptonic widths of the J/psi meson perform... more Abstract: We report a new precise determination of the leptonic widths of the J/psi meson performed with the KEDR detector at the VEPP-4M $ e^{+} e^{-} $ collider. The measured values of the J/psi parameters are:\ Gamma_ {ee}\ times\ Gamma_ {ee}/\ Gamma= 0.3323\ pm 0.0064 (stat.)\ pm 0.0048 (syst.) keV\ Gamma_ {ee}\ times\ Gamma_ {\ mu\ mu}/\ Gamma= 0.3318\ pm 0.0052 (stat.)\ pm 0.0063 (syst.) keV. Assuming $ e\ mu $ universality and using the table value of the branching ratios the leptonic\ Gamma_ {ll}= 5.59\ pm 0.12 ...

Chinese Physics C, 2010

We report results of experiments performed with the KEDR detector at the VEPP-4M e + e − collider... more We report results of experiments performed with the KEDR detector at the VEPP-4M e + e − collider. They include precise measurement of the D 0 and D ± meson masses, determination of the ψ(3770) resonance parameters, and a search for narrow resonances in e + e − annihilation at center-of-mass energies between 1.85 and 3.1 GeV.

Physics Letters B, 2003

A new high precision measurement of the J/ψ-and ψ ′-meson masses has been performed at the VEPP-4... more A new high precision measurement of the J/ψ-and ψ ′-meson masses has been performed at the VEPP-4M collider using the KEDR detector. The resonant depolarization method has been employed for the absolute calibration of the beam energy. The following mass values have been obtained: M J/ψ = 3096.917 ± 0.010 ± 0.007 MeV, M ψ ′ = 3686.111 ± 0.025 ± 0.009 MeV. The relative measurement accuracy has reached 4 • 10 −6 for J/ψ and 7 • 10 −6 for ψ ′ , approximately 3 times better than in the previous precise experiments.

Nuclear Physics B - Proceedings Supplements, 2011

We present preliminary results of a new high-precision determination of the tau lepton mass perfo... more We present preliminary results of a new high-precision determination of the tau lepton mass performed with the KEDR detector at the VEPP-4M ee collider. These results are compared to two recent tau lepton mass measurements at Belle and BaBar.

JETP Letters, 2007

A precise τ lepton mass measurement performed at the VEPP-4M collider with the KEDR detector is r... more A precise τ lepton mass measurement performed at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the τ + τcross section behavior around the production threshold. The result based on 6.7 pb-1 of data is m τ = ± 0.15 MeV. Using 0.8 pb-1 of data collected at the ψ ' peak, we have also determined that Γ ee B ττ (ψ ') = 9.0 ± 2.6 eV.

Nuclear Physics B - Proceedings Supplements, 2008

New measurements of psi(2S), psi(3770) and D meson masses are presented. The results of the scans... more New measurements of psi(2S), psi(3770) and D meson masses are presented. The results of the scans performed were used for determination of the products Gamma×Gamma/Gamma for J/psi and Gamma×Gamma/Gamma for psi(2S).

The paper presents measurements of the longitudinal broadband impedance and beam energy spread of... more The paper presents measurements of the longitudinal broadband impedance and beam energy spread of the beam at the VEPP-4M electron-positron collider in an energy range of 1.0 – 3.5 GeV. In order to measure the longitudinal bunch size at various beam currents we used “PS-1/S1” streak camera with picosecond temporal resolution. The dependence of bunch length from the bunch current at different energies demonstrates a microwave instability threshold. The bunch lengthening was caused by potential well distortion as well. Potential well distortion lengthening was used to estimate a value of the reactive part of the longitudinal impedance of the vacuum chamber of the collider. Observed microwave instability thresholds was used to measure the value of the broadband impedance. The impact of the Touschek effect in the beam energy spread is discussed. ELECTRON BUNCH LENGTH Natural Length A length of an electron bunch is determined by the synchrotron oscillations and has no current dependence ...

Physics Letters B, 2015

We present the analysis of all KEDR data on the determination of J /ψ and ψ(2S) masses. The data ... more We present the analysis of all KEDR data on the determination of J /ψ and ψ(2S) masses. The data comprise six scans of J /ψ and seven scans of ψ(2S) which were performed at the VEPP-4M e + e − collider in 2002-2008. The beam energy was determined using the resonance depolarization method. The detector and accelerator conditions during scans were very different that increases the reliability of the averaged results. The analysis accounts for partial correlations of systematic uncertainties on the masses. The following mass values were obtained: M J /ψ = 3096.900 ± 0.002 ± 0.006 MeV, M ψ(2S) = 3686.099 ± 0.004 ± 0.009 MeV. These results supersede our previous measurements published in 2003 and 2012.

At present the VEPP-4 storage ring facility provides varied experimental programs including HEP, ... more At present the VEPP-4 storage ring facility provides varied experimental programs including HEP, nuclear physics, synchrotron radiation, polarized electron/positron beam research, etc. Until now, the studies were mainly performed at the beam energy below 2 GeV but a strong interest of experimentalists encourages us to increase the beam energy up to 5 GeV. Reliable and high-performance operation at high energy is a challenge for the machine. Here we discuss the recent experimental results at the low energy, and prospects and constraints of the energy ramp.

EPJ Web of Conferences, 2019

The present status of two operating BINP electron-positron colliders VEPP-2000 and VEPP-4M is given.

The purpose of the work is to expand the electronic database "Electronic structure of atoms" with... more The purpose of the work is to expand the electronic database "Electronic structure of atoms" with the information on the negative ions of various chemical elements. As far as the authors are aware, at present there is no specialized database on negative ions in the scientific literature and Internet. The collection and analysis of information on atomic systems can be represented in a tabular or graphical representation. It is convenient to have accurate and extensive data on the spectra of elements in the form of tables, while the graphical form is good for cognitive understanding of the electronic structure of atomic systems.