Recommissioning the Modernized VEPP-2000 Electron–Positron Collider

The VEPP-2000 electron–positron collider has been operating at the Budker Institute of Nuclear Physics (BINP) since 2010. Applying the concept of round colliding beams allowed the record value of the beam–beam parameter ξ ～ 0.12 to be reached. The upgrading of the VEPP-2000 complex, including the connection to the new BINP Injection Complex and modification of the electron–position booster and the BEP–VEPP-2000 transfer channels to work at 1 GeV, resulted in a significant increase in luminosity. Work on statistical data collection using detectors is in progress.     

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.     

The status of VEPP-4

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.     

Measurement of R at VEPP-2000

The new e+e-storage ring,VEPP-2000,is being commissioned at Budker Institute of Nuclear Physics,Novosibirsk.Measurement of the total cross section e+e-→hadrons in the whole VEPP-2000 energy range is one of the main goals of the new experiments.We discuss the goals of the measurement and the expected systematic errors.     

New tracking system of the SND detector

A new tracking system (TS) of the Spherical Neutral Detector (SND) for experiments at the VEPP-2000 e ⁺ e ^? collider is described. The TS is completely assembled, mounted on the detector, and ready for collecting data from the VEPP-2000. Test experiments with cosmic-ray events and VEPP-2000 beams showed a stable operation of the system. The simulation, calibration, and reconstruction procedures were debugged by using available data.     

The VEPP-2000 electron-positron collider: First experiments

In 2007, at the Institute of Nuclear Physics (Novosibirsk), the construction of the VEPP-2000 electron-positron collider was completed. The first electron beam was injected into the accelerator structure with turned-off solenoids of the final focus. This mode was used to tune all subsystems of the facility and to train the vacuum chamber using synchrotron radiation at electron currents of up to 150 mA. The VEPP-2000 structure with small beta functions and partially turned-on solenoids was used for the first testing of the “round beams” scheme at an energy of 508 MeV. Beam-beam effects were studied in strong-weak and strong-strong modes. Measurements of the beam sizes in both cases showed a dependence corresponding to model predictions for round colliding beams. Using a modernized SND (spherical neutral detector), the first energy calibration of the VEPP-2000 collider was performed by measuring the excitation curve of the phimeson resonance; the phi-meson mass is known with high accuracy from previous experiments at VEEP-2M. In October 2009, a KMD-3 (cryogenic magnetic detector) was installed at the VEPP-2000 facility, and the physics program with both the SND and LMD-3 particle detectors was started in the energy range of 1–1.9 GeV. This first experimental season was completed in summer 2010 with precision energy calibration by resonant depolarization.     

Status and prospects of VEPP-2000 electron-positron collider

High energy physics experiments were started at VEPP-2000 at the end of 2010; the third experimental run was finished in July 2013. The last run was devoted to the energy range 160–510 MeV in a beam. Compton backscattering energy measurements were used for the regular energy calibration of the VEPP-2000, together with resonance depolarization and NMR methods. The conception of the round colliding beam lattice along with precise orbit and lattice correction yielded a record high peak luminosity of 1.2 × 10³¹ cm^?2 s^?1 at 510 MeV and an average luminosity of 0.9 × 10³¹ cm^?2 s^?1 per run. A total betatron tune shift of 0.174 was achieved at 392.5 MeV. This corresponds to the beam-beam parameter ξ = 0.125 in terms of the collision point. The injection system is currently modernized to allow injection of particles at the VEPP-2000 energy maximum and the elimination of the existing lack of positrons.     

Equipment for soft X-Ray lithography on the VEPP-4M

An X-ray scanner for X-ray mask lithography is described. It is mounted onto the synchrotron radiation (SR) beamline of the VEPP-4M storage ring. The main advantage of this scanner is the possibility of varying the SR spectral range within wide limits and its fine tuning for solving specific technical tasks by changing the working energy of the VEPP-4M and using corresponding filters, which is illustrated by tables and plots of the calculated spectra. Calculated estimates of the lithographic resolution of lithographic complex, exposure times for various types of X-ray masks, and thicknesses of their masking layers providing the required level of X-ray mask contrast are given.     

Experimental investigation of coupling impedances of the VEPP-4M electron-positron collider

The interaction of a beam with vacuum chamber elements via induced electromagnetic field is analyzed in the frequency domain using frequency-dependent coupling impedances. The knowledge of the impedances makes it possible to estimate the stability conditions for propagation of the beam. The calculation of impedances of accelerators like the VEPP-4M electron-positron collider with a large number of inhomogeneities in the vacuum chamber is a complicated and time-consuming problem. However, the impedances can be studied in such cases experimentally by analyzing the propagation of the beam. The results of experiments on the longitudinal and transverse impedances of VEPP-4M are considered. We describe a method for measuring the local transverse impedance ensuring a higher sensitivity as compared to the methods used earlier.     

Software for Monitoring and Controlling the VEPP-5 Damping-Ring Operation with Upgraded Electronics of Beam-Position Sensors

Physics of Particles and Nuclei Letters - Work on developing new software tools for monitoring and controlling the VEPP-5 damping-ring (DR) operation with upgraded stations of beam-position sensors...     

Probing Beam Collective Effects in the Damping Ring of the VEPP-5 Injection Complex

Physics of Particles and Nuclei Letters - The in-depth understanding of beam collective effects in the damping ring (DR) of the VEPP-5 injection complex at BINP is essential for optimizing its...     

Measurement of the VEPP-4M Collider Energy Spread in the Entire Energy Range

Physics of Particles and Nuclei Letters - The energy spread of the VEPP-4M electron–positron collider at the Budker Institute of Nuclear Physics was measured in the 1100–4750 MeV range...     

New optical diagnostics of the VEPP-4M collider

The experiments in measuring the dynamic aperture and beam energy spread of the VEPP-4M collider [1] are described. The optical diagnostics of the accelerator were applied for these purposes. The text was submitted by the authors in English.     

Status of Vepp-2000 BINP Electron–Positron Collider

Physics of Particles and Nuclei Letters - VEPP-2000 is the only electron–positron collider with round beams. This factor enables one to increase the beam–beam effect limit. During the...     

Experiments on the physics of charged particle beams at the VEPP-4M electron-positron collider

The VEPP-4M accelerator facility with a universal KEDR detector is designed to conduct experiments with colliding electron-positron beams. High-energy physics, nuclear physics, and studies using synchrotron radiation are the main directions of research with this facility. In addition, experiments on poorly explored issues in the physics of beams in the electron-positron storage ring and methodological studies to prepare an experiment aimed at testing corollaries of the CPT theorem for an electron and a positron are regularly conducted at the VEPP-4 facility. A number of works performed in recent years are described: studies to increase the accuracy of comparing the electron and positron spin precession frequencies by the resonant depolarization method; measurements of the count rate of Touschek electrons as a function of the beam energy in a wide range; comparison of the methods for measuring the beam energy spread; a study of the electron beam dynamics when a nonlinear betatron resonance is crossed.     

Comparative certification of secondary-electron multipliers within the ultrasoft X-ray range

The results of studying the band characteristics and the efficiency of recording the secondary-electron multipliers VEU-6 and VEU-GOI (manufactured by the Vavilov State Optical Institute (GOI), St. Petersburg) within the ultrasoft X-ray range are given. The measurements were carried out at the metrological station Kosmos with the use of synchrotron radiation from the storage ring VEPP-4M (Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk) in monochromatic radiation at a photon energy of 268 eV. A strong irregularity in the band characteristics of both VEU-6 and VEU-GOI has been found. Their quantum efficiencies are estimated. The measurements are a continuation of the works on calibration of the equipment of the Space Solar Patrol (developed by GOI) using synchrotron radiation from the VEPP-4M storage ring (project MNTTs no. 2500).     

Measurement of the Cross Section for the Process $${e^{+}e^{-}}{\to}{K}^{{+}}{K}^{{-}}{\pi}^{{0}}$$ with the SND Detector at Collision Energies of $$\sqrt{{s}}{=}{1.3{-}2.0}$$ GeV in the Center-of-Mass Frame

Physics of Atomic Nuclei - In an experiment with the SND detector at the VEPP-2000 $$e^{+}e^{-}$$ collider, the cross sections for the processes $$e^{+}e^{-}\to K^{+}K^{-}\pi^{0}$$ and...     

Study of the process e^＋e^- →π^＋π^-π^0π^0 at energies √s 〈 1 GeV

In an experiment with the Spherical Neutral Detector at VEPP-2M collider the cross section of the process e^＋e^- →π^＋π^-π^0π^0 was measured. At energies √s 〈 920 MeV this cross section was measured for the first time. The energy dependence of the cross section is well discribed by the vector dominance model with contributions from p, p＇, p＂ mesons. The decay probability ρ→π^＋π^-π^0π^0 was found to be Bρ = （1.60±0.74±0.18） × 10^-5. The upper limit for the decay ω→π^＋π^-π^0π^0 was improved by two orders of magnitude compared to the previous measurements and is Bω 〈 2 × 10^-4 at 90% confidence level.