VEPP-2000 Collider Research Articles

The DQM system for the SND detector

The SND detector has been operating at the VEPP-2000 collider (BINP, Russia) for several years. We present its new DQM system.The system deals with multiple parameters being numbers, histograms or user opinions to form a data quality decision (good, bad, etc). It calculates SND subsystem and overall statuses and produces summaries available via web-interface. The system supports multiple parameter sets for different usages like daily checks, precise subsystem control, preparing data for processing, etc. The parameter values are analyzed using special ROOT macros yielding quality checks that could be supplemented or corrected by users.The system is a part of a new SND information system implemented as a web application using Node.js and MySQL. The ROOT macros are written by SND subsystems experts using a simple framework. Histograms are displayed using JSROOT.The system is put into production. It is consistent, however there are some improvements to implement.

Overview of the CMD-3 recent results

The CMD-3 detector started data taking at the electron-positron collider VEPP-2000 in December 2010 with a goal to collect about 1 fb−1. The collected data sample corresponds to an integrated luminosity of 200 pb−1 in the center-of-mass energy range from 0.32 up to 2 GeV. This paper reports recent results on the hadronic cross sections measurements with the CMD-3 detector.

Measurement of the e+e\u2212\u2192 \u03b7\u03c0+\u03c0\u2212 cross section with the CMD-3 detector at the VEPP-2000 collider

The cross section of the process e+e−→ ηπ+π− is measured using the data collected with the CMD-3 detector at the VEPP-2000 collider in the center-of-mass energy range from 1.1 to 2.0 GeV. The decay mode η → γγ is used for η meson reconstruction in the data sample corresponding to an integrated luminosity of 78.3 pb−1. The energy dependence of the e+e−→ ηπ+π− cross section is fitted within the framework of vector meson dominance in order to extract the Γ(ρ(1450) → e+e−) mathcal{B} (ρ(1450) → ηπ+π−) and the Γ(ρ(1700) → e+e−) mathcal{B} (ρ(1700) → ηπ+π−) products. Based on conservation of vector current, the analyzed data are used to test the relationship between the e+e−→ ηπ+π− cross section and the spectral function in τ−→ ηπ−π0ντ decay. The e+e−→ ηπ+π− cross section obtained with the CMD-3 detector is in good agreement with the previous measurements.

Study of the process e+e− → K+K−η with the CMD-3 detector at the VEPP-2000 collider

The process e+e−→K+K−η has been studied in the center-of-mass energy range from 1.59 to 2.007 GeV using the data sample of 59.5 pb−1, collected with the CMD-3 detector at the VEPP-2000 e+e− collider in 2011, 2012 and 2017. The K+K−η final state is found to be dominated by the contribution of the ϕ(1020)η intermediate state. The cross section of the process e+e−→ϕ(1020)η has been measured with a systematic uncertainty of 5.1% on the base of 3009 ± 67 selected events. The obtained cross section has been used to calculate the contribution to the anomalous magnetic moment of the muon: aμϕη(E<1.8GeV)=(0.321±0.015stat±0.016syst)×10−10, aμϕη(E<2.0GeV)=(0.440±0.015stat±0.022syst)×10−10. From the cross section approximation the ϕ(1680) meson parameters have been determined with better statistical precision, than in previous studies.

Beam-based mapping of pulsed septum stray field at VEPP-2000 collider

Various beam-based methods are widely used for machine study and accurate tuning. Beam closed orbit (CO) responses are routinely used worldwide for magnetic elements alignment and lattice correction. The paper presents the beam-based field mapping technique, applied for measurement of pulsed septum magnet stray field at VEPP-2000 electron-positron collider. Relatively slow pulse of weak leakage field disturbs the CO allowing detecting field longitudinal integral. While scanning with transverse coordinate in wide range one can measure the field map of the localized perturbation at machine in situ.

Charged particle identification using the liquid Xenon calorimeter of the CMD-3 detector

Abstract This paper describes a currently being developed procedure of the charged particle identification for CMD-3 detector, installed at the VEPP-2000 collider. The procedure is based on the application of the boosted decision trees classification method, and uses as input variables the specific energy losses of charged particles in the 14 layers of the liquid Xenon calorimeter. The performance of the procedure is demonstrated by an example of the extraction of events of e + e − → K + K − ( γ ) process in the center of mass energy range from 1.28 to 1.65 GeV.

Recent results from SND detector at VEPP-2000 collider

Recent results on e+e−annihilation to hadrons from SND experiment at VEPP-2000 collider are presented. Corresponding data set is about 200 pb−1 of integrated luminosity collected at the energy region below 2 GeV. The processes e+e− → π+π− , π0γ, ωπ0, π+π−π0, ηπ+π−π0, η, π+π−4π0 have been studied. Searches for e+e− annihilation to C-even resonances η and f1(1285) were done.

Recent results of the hadronic cross section measurements with the CMD-3 detector at e+e− collider VEPP-2000

A brief review of the recent results on the hadronic cross section measurements with the CMD-3 detector at the e+e− collider VEPP-2000 is given. Focus is made on the processes with charged kaons in multihadron events, which have a strong impact on strange meson spectroscopy and form factors that are important ingredients in the Dalitz plot analysis. Experimental data relevant to the topic are presented from the broad energy range covered by VEPP-2000 and compared to earlier measurements by the different collaborations. The analysis is based on the integrated luminosity of about 100 pb−1 collected in 2011, 2012 and 2017.

Current status of luminosity measurement with the CMD-3 detector at the VEPP-2000 collider

The CMD-3 detector started data taking at the electron-positron collider VEPP-2000 [1] in December 2010. The collected data sample corresponds to an integrated luminosity of 87 pb−1 in the c.m. energy range from 1.06 up to 2 GeV and 91 pb−1 from 0.32 to 1.06 GeV. The integrated luminosity was measured by counting e+e−→ e+e− and e+e−→ γγ events, allowing additional photons in the final state. Preliminary results of the luminosity measurement are presented for various energy ranges and its accuracy is estimated to be 1%.

A Web-based control and monitoring system for DAQ applications

A comprehensive and efficient environment and data monitoring system is a vital part of any HEP experiment. In this paper we describe the software web-based framework which is currently used by the CMD-3 Collaboration at the VEPP-2000 Collider and partially by the Muon g-2 experiment at Fermilab to monitor the status of data acquisition and the quality of data taken by the experiments. The system is designed to meet typical requirements and cover various use-cases of DAQ applications, starting from the central configuration, slow control data monitoring, data quality monitoring, user-oriented visualization, control of the hardware and DAQ processes, etc. Being an intermediate middleware between the front-end electronics and the DAQ applications the system is focused to provide a high-level coherent view for shifters and experts for robust operations. In particular, it is used to integrate various experiment dependent monitoring modules and tools into a unified Web oriented portal with appropriate access control policy. The paper describes the design and overall architecture of the system, recent developments and the most important aspects of the framework implementation.

Preliminary results on CMD-3 measurement of e+e−→ π+π− cross section

The CMD-3 detector has been successfully collecting data at the electron-positron collider VEPP-2000 since December 2010. The first scan below 1 GeV for a π+π− measurement was performed in 2013. The collected data sample corresponds to about 18 pb−1 of integrated luminosity in this energy range. Analysis of the e+e−→ π+π− cross section is in progress. Status of this measurement are presented.

Recent results from CMD-3

Regular data taking with the CMD-3 at the electron-positron collider VEPP-2000 is under way since 2010. The collected data sample corresponds to about 200 inverse picobarns of integrated luminosity per detector in the energy range from 0.32 up to 2 GeV, with a goal to collect about 1 fb−1 during next five years. Some of the recent results from the CMD-3 detector are discussed.

Study of the process e+e−→ K+K−π0 in the center-of-mass energy range 1.2–2 GeV with the CMD-3 detector

The process e+ e−→ K+ K−π0 has been studied in the center-of-mass energy range from 1.2 to 2 GeV using a 80.6 pb−1 data sample collected with the CMD-3 detector at the electron-positron collider VEPP-2000. Preliminary results of the cross-section measurement are presented.

Status and Prospects of VEPP-5 Injection Complex

Since 2016, the VEPP-5 injection complex has been supplying the VEPP-4M and the VEPP-2000 colliders with electrons and positrons through the K-500 transport channel. By now the injection complex has demonstrated the capability to support the routine operation of both colliders. Nevertheless, work is actively continuing to improve the stability and efficiency of the facility. In this paper, a description of the injection complex, its operation experience, and prospects are presented.

Analysis of the Parameters of Pulse Signals by the Correlation Method Using the Example of High-Voltage Inflectors of the Damping Ring of a Vepp-5 Injection Complex

After the VEPP-2000 and VEPP-4M colliders are switched to being supplied by beams from the VEPP-5 injection complex, the problem of ensuring the operation stability of the damping ring inflectors arises. Software on the basis of correlation analysis has been created to study the amplitude and delay deviations of the pulses of inflector generators. This allows the delay deviations of 1 ns for inflector signals that were digitized using ADC with a sampling frequency of 200 MHz to be observed. The dependence of the generator- delay deviation on the network voltage has been also discovered as a result of long-term observations.

Development of μ-RWELL detectors for the upgrade of the tracking system of CMD-3 detector

Abstract An upgrade of tracking system of Cryogenic Magnetic Detector (CMD-3) is proposed using microresistive WELL technology. CMD-3 is a general purpose detector operating at the VEPP-2000 collider at Budker Institute of Nuclear Physics and intended for studies of light vector mesons in the energy range between 0.3 GeV and 2 GeV. The new subsystem consists of double-layer cylindrical detector and the end-cap discs. Two prototypes, micro-RWELL and micro-RWELL-GEM were built and tested. Gas amplification of micro-RWELL detector was measured with several gas mixtures and maximum gain between 20000 and 30000 was observed. However, maximum gain is fluctuating from measurement to measurement by a factor of 2 and thus a safety margin of 2–3 is needed to provide reliable operation of the device. In order to increase the signal GEM was added to micro-RWELL, new prototype was tested with the same gas mixtures and gains above 10 5 have been demonstrated. Time resolution achieved for both prototypes are 7 ns for micro-RWELL and 4 ns for micro-RWELL-GEM.

Study of e+e− annihilation to hadrons with SND at the VEPP-2000 collider

In 2017 the detector SND resumed data taking at the VEPP-2000 e+e− collider after its upgrade. Using of a new positron source allows significantly increase collider luminosity. We report the current status of the experiment and recent result of data analysis, in particular, on the processes e+e−→π+π−, nn‾, K+K−η, π+π−η, KSKLπ0, π+π−π0η, π0γ, ωπ0, and η→e+e−.

Commissioning of the Electron-Positron Collider VEPP-2000 after the Upgrade

The VEPP-2000 electron–positron collider has been operating at BINP since 2010. Applying the concept of round colliding beams allows us to reach the record value of the beam–beam parameter, ξ ~ 0.12. The VEPP-2000 upgrade, including the connection to the new BINP Injection Complex, the improvement of the BEP booster, and the BEP–VEPP-2000 transfer channels for operation at 1 GeV, substantially increases the installation luminosity. Data collection is in progress.

Measurement of the hadronic cross sections with the CMD-3 and SND detectors at the VEPP-2000 collider

Since December 2010 the CMD-3 and SND detectors detectors collect data at the VEPP-2000 electron-positron collider. In 2013-2015 the injection facility of the collider has undergone an upgrade of the injection system. The new BINP injection complex has been connected to the VEPP-2000 collider, so the restrictions connected to the lack of positrons and limited beam energy transfer do not apply any more. The collider luminosity in whole energy range is restricted now only by beam-beam effects. VEPP-2000 collider started to collect data with two detectors at 2016 year. The collected data sample since 2010 corresponds more than 100 pb-1 of integrated luminosity per detector in the c.m. energy between 0.32 and 2GeV. We will report here results of analysis of various hadronic cross sections from detectors both published and preliminary. These measurements are important by themselves and also because of the implications for anomaly of the magnetic moment of a muon (g-2) discrepancy.

Recent results at the ϕ-meson region from the CMD-3 detector at the VEPP-2000 collider

This report is devoted to the recent results of the study of the processes e+e− → KSKL, K+K−, π+π−2π0, 2π+2π−, ηγ at the ϕ-meson region with the CMD-3 detector at the VEPP-2000 collider. From the combined analysis of KSKL and K+K− final states the ϕ-meson parameters were measured, and the obtained ratio of gϕK+K− and gϕKSKL couplings was found to be compatible with the isospin symmetry. From the analyzes of the π+π−2π0 and 2π+2π− final states the branching ratios ℬ(ϕ → π+π−2π0) and ℬ(ϕ → 2π+2π−) were determined.