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.     

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.     

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.     

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.     

Current Status and Planned Upgrades of the VEPP-5 Injection Complex

Physics of Particles and Nuclei Letters - The VEPP-5 injection complex, consisting of two linacs and a damping storage ring, delivers electron and positron beams to the VEPP-4M and VEPP-2000...     

Hybrid recoil mass analyzer at IUAC — First results using gas-filled mode and future plans

Hybrid recoil mass analyzer (HYRA) is a unique, dual-mode spectrometer designed to carry out nuclear reaction and structure studies in heavy and medium-mass nuclei using gas-filled and vacuum modes, respectively and has the potential to address newer domains in nuclear physics accessible using high energy, heavy-ion beams from superconducting LINAC accelerator (being commissioned) and ECR-based high current injector system (planned) at IUAC. The first stage of HYRA is operational and initial experiments have been carried out using gas-filled mode for the detection of heavy evaporation residues and heavy quasielastic recoils in the direction of primary beam. Excellent primary beam rejection and transmission efficiency (comparable with other gas-filled separators) have been achieved using a smaller focal plane detection system. There are plans to couple HYRA to other detector arrays such as Indian national gamma array (INGA) and 4π spin spectrometer for ER tagged spectroscopic/spin distribution studies and for focal plane decay measurements.     

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).     

NICA at JINR: New prospects for exploration of quark-gluon matter

A new scientific program is proposed at the Joint Institute for Nuclear Research (JINR) in Dubna aimed at studies of hot and dense baryonic matter in the wide energy range from 2 GeV/u kinetic energy in fixed target experiments to $\sqrt {s_{NN} } = 4 - 11$ GeV/u in the collider mode. To realize this program the development of the JINR accelerator facility in high-energy physics (HEP) has been started. This facility is based on the existing superconducting synchrotron??the Nuclotron. The program foresees both experiments at the beams extracted from the Nuclotron, and the construction of a heavy-ion collider??the Nuclotron-based Ion Collider fAcility (NICA) which is designed to reach the required parameters with an average luminosity of L = 10²⁷ cm^?2 s^?1.     

Recent radioactive ion beam program at RIKEN and related topics

Recent experimental programs at RIKEN concerning RI beams are reviewed. RIKEN has the ring cyclotron (RRC) with high intense heavy-ion beams and large acceptance fragment separator, RIPS. The complex can provide high intense RI-beams. By using the high intense RI-beams, a variety of experiments have been done. Recently, nuclear structure for unstable nuclei has been paid much attention. In special, disappearance and appearance of magic numbers are discussed experimentally and theoretically. Thus, in this review, related experiments concerning disappearance and appearance of magic numbers are described. Finally, future project in RIKEN, RI-beam factory. is introduced briefly.     

Development and application of the hadronic event generators in HEP

We have suggested a new approach to the development and use of Monte Carlo event generators in high-energy physics (HEP). It is a component approach where a complex numerical model is composed from standardized components. Our approach opens a way to organize a library of HEP model components and provides a great deal of flexibility for the construction of powerful and realistic numerical models. To support this approach, we have designed the NiMax software system (framework) that is written in C++.     

Effect of polarization on femtosecond pulsed laser ablation of surface relief gratings using a novel interferometer

In this paper, we report the effects of polarization state of individual beams in ablation of surface relief gratings using a two-beam interferometric technique. We have carried out ablation experiments on (1 1 1) silicon to form surface relief gratings by interfering two femtosecond laser beams under different polarization combinations. Four combinations of polarization were studied, i.e., s-: s-polarization, s-: p-polarization, p-: p-polarization and circular-: circular-polarization (c-: c-polarization). A novel interferometer was used for the investigation. The grating depths, surface roughness and ablation thresholds have been shown to depend on the polarization state of the interfering beams.     

Multibeam effects on fast-electron generation from two-plasmon-decay instability

Experiments with multiple laser beams have been carried out in both spherical and planar geometry to study two-plasmon-decay instability, the predominant source of suprathermal electrons in direct-drive inertial confinement fusion experiments. These electrons are observed using the hard x rays generated through electron-target interactions. The experiments show for the first time that the total overlapped intensity governs the scaling of the suprathermal-electron generation regardless of the number of overlapped beams, in contrast to conventional theories that are based on the single-beam approximation.     

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.     

First results of the application of scanning XRF analysis with synchrotron-radiation beams from the VEPP-3 to study the spatial distribution of trace elements in samples of stratiform chromite ores

A sample from chromite horizon UG1 of the platiniferous Bushveld complex (South Africa) is studied by scanning X-ray fluorescence (XRF) microanalysis using synchrotron-radiation beams from the VEPP-3 storage ring. The sample contains plagioclase and chromite layers 3–5 mm in thickness. The experimental study is conducted at excitation energies of 15 and 30 keV; the spot size of the excitation radiation is 0.1 ± 2 mm; and the scanning step is 100 µm. The distribution profiles of more than 20 trace elements over the surface of the sample are obtained.     

Strangeness Nuclear Physics at J-PARC

After the big earthquake in the east part of Japan on March 11, 2011, the beams in the hadron experimental hall at J-PARC have been successfully recovered in February, 2012. The experimental program using pion beams is now on-going with the primary proton beam power of ~5 kW. Before a long summer shutdown scheduled in 2013, several experiments in strangeness nuclear physics are going to take data. In this period, we anticipate the beam power would exceed 10 kW and the experiments to use K ^? beams will start. The experimental program is explained briefly.     

High accuracy comparison of the electron and positron magnetic moments

A comparison of the electron and positron anomalous magnetic moments has been performed using the resonance depolarization method for the VEPP-2M storage ring beams. It has been shown, that the difference between anomalous magnetic moments of electron and positron doesn't exceed 1.0 × 10^?5 with 95% confidence level in agreement with CPT-theorem prediction on equality of the particle and antiparticle magnetic moments. The achieved accuracy is two orders better than that available up to now.     

Nuclear Physics Programs for the Future RIBs Facility in Korea

We present nuclear physics programs based on the planned experiments using rare isotope beams (RIBs) for the future Korean Rare Isotope Beams Accelerator facility(KRIA). This ambitious facility has both an Isotope Separation On Line (ISOL) and fragmentation capability for producing RIBs and accelerating beams of wide range mass of nuclides with energies of a few to hundreds MeV per nucleon. Low energy RIBs at Elab = 5 to 20 MeV per nucleon are for the study of nuclear structure and nuclear astrophysics toward and beyond the drip lines while higher energy RIBs produced by inflight fragmentation with the reaccelerated ions from the ISOL enable to explore the neutron drip lines in intermediate mass regions. The planned programs have goals for investigating internal structures of the exotic nuclei toward and beyond the nucleon drip lines by addressing the following issues: how the shell structure evolves in areas of extreme proton to neutron imbalance; whether the isospin symmetry maintains in isobaric mirror nuclei at and beyond the drip lines; how two-proton radioactivity affects abundances of the elements; what the role of the continuum states including resonant states above protondecay threshold in exotic nuclei is in astrophysical nuclear reaction processes, and how the nuclear reaction rates triggered by unbound proton-rich nuclei make an effect on rapid proton capture processes in a very hot stellar plasma.     

Infrared multiple-photon dissociation of ion-molecules in a beam

First experiments on the infrared multiple-photon dissociation with ion molecules in beams have been carried out. A mass selected beam of SF⁺₅ parent ions is crossed with a focused pulsed CO₂ laser beam. Using mass spectroscopy for the detection, fragmentation into SF⁺₄ and SF⁺₃ has been observed. The relative yield and power dependence have been measured. Features of the MPD of ions in beams are discussed.