VEPP-3 Storage Ring Research Articles

Measurement of the Analyzing Power of the Reaction of Photoproduction of Negative Pions in the Δ(1232) Resonance Region

Measurements are presented of the tensor analyzing power of the Т21 component of photoproduction of a π–meson on a deuteron. The measurements were performed on the VEPP-3 storage ring using an internal tensor-polarization deuterium target. The experimental results are compared with theoretical calculations.

Measurement of the components of the tensor analyzing power in the reaction γd → ppπ − at high proton momenta

Results obtained by measuring three components of the tensor analyzing power in the reaction of π− -meson photoproduction on a deuteron at final-proton momenta between 300 and 700 MeV/c are presented. The measurements in question were performed at the VEPP-3 storage ring by using its internal deuterium-gas target featuring a tensor polarization with the aid of detection of two protons in coincidence. The experimental results obtained in this way are compared with their counterparts calculated theoretically.

Upgrading of the synchrotron radiation beam stabilization system of the VEPP-3 storage ring

The basic components of a new system of stabilization of synchrotron radiation beams of the VEPP-3 storage ring are developed and tested. This system will ensure the beam position measurement and its stabilization not only over the vertical but also over the horizontal angle and coordinate. It will be also possible to use this system in parallel to the previously developed stabilization system, which registers only the vertical components.

The development of high resolution coordinate detectors for the DEUTERON facility

The DEUTERON internal target facility at the VEPP-3 storage ring at BINP is intended for the experiments on interaction of electrons and positrons with proton and deuteron. These experiments require high resolution tracking detectors which can provide the energy and angles of scattered electron.The prototype detector with a sensitive area of 160 × 40 mm2 was built and proved to be operational. It consists ofthree cascades of gaseous electron multiplier (GEM), the readoutstructure and detector electronics. Readout structure has 640 stripswhich are uniformly distributed in two layers skewed by 30degrees. Electronics of the detector includes APC128 ASICs, AlteraCyclone III FPGA, 100 MBit ethernet. In the APC128 ASIC each channelhas a separate analog pipeline consisting of 32 cells which arecyclically switched by a global clock synchronized to the bunchcrossing rate ( ∼ 4 MHz).For the needs of DEUTERON facility the expected resolution of lessthan 100 μm and thickness of ∼ 0.15% of radiation lengthare considered to be quite satisfactory. The latest results obtainedat the test beam facility at the VEPP-4M collider show that detectoris fully operational with maximum detection efficiency reached98%.

Development of high resolution tracking detectors with Gas Electron Multipliers

Cascaded Gas Electron Multipliers (GEM) allow to construct detectors for charge particles tracking with high spatial resolution and rate capability. Such detectors can withstand high background fluxes up to 105 particles/mm2/s and determine track coordinates with precision of 50 – 70 micron. These remarkable features of GEM govern the use of this technology in a number of experiments at the Budker Institute of Nuclear Physics. In this paper the current status and progress in the performance studies and the development of the detectors for the tagging system of the KEDR experiment at the VEPP-4M collider and for the DEUTERON facility at the VEPP-3 storage ring will be covered. The new proposals for the upgrade of tracking and trigger system of the CMD-3 detector, the tracking detectors for the extracted beam from the VEPP-4M storage ring and the tracking detectors for the polarimeter at the VEPP-4M with the use of GEM technology will be discussed.

Beam energy measurements for an experimenton elastic e±p scattering at the VEPP-3 storage ring

A precise comparison of the cross sections for the elastic scattering of electrons and positrons on protons was performed recently at the VEPP-3 storage ring in Novosibirsk, Russia. To provide the proposed accuracy, the energies of the electron and positron beams used during the experiment needed to be carefully maintained. This paper describes the special beam energy measurement system used in this experiment. This system is based on measuring the maximum energy of laser photons backscattered from electron and positron beams. It provides continuous beam energy measurements with a total relative uncertainty of less than 4.4·10−5.

Tagging system for almost-real photons at VEPP-3 storage ring

At BINP the construction of the tagging system for almost-real photons (TS) is in progress. The energy of tagging photons can be up to 1.5 GeV. The projected energy resolution of TS is better then 1%. For at least a half of photons the linear polarization can be determined. The tagging system will extend the possibilities for photoreaction studying at VEPP-3 significantly. TS would allow to perform a complete kinematics reconstruction, thus permitting a reliable rejection of the background processes; to extend the measurements to higher photon energy; to enabling Σ-asymmetry measurements and double polarization experiments.

Two-photon exchange contribution in elastic electron-proton scattering, experiment at the VEPP-3 storage ring

We describe a precise measurement of the ratio of the ( e + p ) to ( e − p ) elastic scattering cross sections. This comparison is sensitive to the effect of two-photon exchange contributions which may be the cause for inconsistent extractions of the proton form factors obtained using different methods. The experiment was performed at storage ring VEPP–3, Novosibirsk at energies of positron/electron beams of 1.0 and 1.6 GeV with electron/positron scattering angles θ = 65÷105° for the first case and 15÷25° and 55÷75° for the second case. Details of the experiment and the preliminary results are presented.

High resolution tracking detectors with cascaded Gaseous Electron Multipliers

Gaseous Electron Multiplier(GEM)-based position sensitive detectors are used and planned to be used in several experiments in the Budker Institute of Nuclear Physics. At present eight triple-GEM detectors are installed in the KEDR experiment at the VEPP-4M collider where they operate in the tagging system measuring momenta of electrons and positrons after two-photon interactions. Several triple-GEM detectors made of very light components are planned to be installed in the DEUTERON experiment at the VEPP-3 storage ring. The first detector of this type is assembled and tested with dedicated electronics. We plan also to build large cylindrical GEM-based detector with two layers of cylindrical triple-GEMs of 60 cm inner diameter. This project is now discussed for the Cryogenic Magnetic Detector (CMD-3) at the VEPP-2000 collider.

Molecular and nanostructured peculiarities of biological tissues in various functional states

Analyzing structural peculiarities of biological polymers at the molecular and nanosized scales (1–1000 A) provides new possibilities to study their functioning. Revolutionary concepts in the study of nanostructured systems are being stimulated by revolutionary instrumentation related to the development of structural methods based on the use of synchrotron radiation, making it possible to investigate the structural dynamics of a functioning biological object. The first experimental study of biological tissues using synchrotron radiation was performed at VEPP-3 storage ring, and measurements are now being performed at the National Research Center Kurchatov Institute. In this brief review we describe the use of synchrotron radiation in biology and medicine in (i) fundamental programs of structural biology and (ii) medical programs.

Scanning X-ray microanalysis of bottom sediments using synchrotron radiation from the BINP VEPP-3 storage ring

Combining the features of synchrotron radiation (low angular divergence and continuous spectrum, natural polarization, and high intensity) with the use of modern X-ray optics (polycapillary lenses) and registering devices results in a new quality of analysis: measuring picogram concentrations of a broad set of elements with micron spatial resolution. Using a dedicated experimental station and developed methodologies, numerous scanning microanalyses of bottom sediments is performed to obtain a time series of geochemical indicators of paleoclimate in the Central Asian region. The detection limit under optimum conditions is 5 × 10−5% with a spatial resolution of ∼100 μm.

Microbeam X-ray lithography apparatus for direct production of deep LIGA structures

A microbeam X-ray lithography apparatus, a new device for the direct production of microstructures in thick layers of X-ray resists, in particular, for the fabrication of X-ray lithography masks, was developed on the basis at the LIGA station of the VEPP-3 storage ring of the Siberian Center of Synchrotron and Terahertz Radiation. A microstructure pattern with given arbitrary topology was produced directly in a SU-8 negative resist layer up to 1 mm thick on a substrate moved in a vector mode using a collimated beam of synchrotron radiation with a special software. The design of the device and its technological capabilities and limitations are described. Examples of the fabricated microstructures with a high aspect ratio and X-ray lithography masks are presented.

X-ray stations based on cylindrical zoom lenses for nanostructural investigations using synchrotron radiation

The main results of the development of X-ray stations are presented. These stations are intended to solve problems concerning the structural biology of tissues at a high time resolution with the help of synchrotron radiation (SR) generated by the VEPP-3 storage ring (Siberian center of SR, Novosibirsk) and the Siberia-2 storage ring (National Research Centre Kurchatov Institute and the centre of nano-, bio-, information, and cognitive sciences, Moscow). The issues of selecting the optical scheme and basic parameters of X-ray optical systems are discussed. Photographs of the original designs of the constructed equipment are given. A modular approach to designing experimental facilities based on self-contained units and methods of focusing a monochromatic SR beam in the required spectral range have been developed. The technique of X-ray beam focusing by means of optical zoom lenses has been implemented. Experimental results that illustrate the possibilities of the SR-beamline hardware used for X-ray diffraction investigation of different biological objects with the help of different recording systems are presented.

GEM-based detectors for SR imaging and particle tracking

Status of several projects under development in Budker INP with GEM-based detectors for synchrotron radiation imaging and particle tracking is reviewed. These are namely: the detector for imaging of explosions(DIMEX) at SR beam, the detector for WAXS studies at SR beam (OD4), the triple-GEM detectors for the tagging system of KEDR experiment at VEPP-4M collider and the triple-GEM detectors for the tagging system of Deuteron experiment at VEPP-3 storage ring.

Absolute calibration of X-ray optical elements and detectors at a wavelength of 46.9 nm

The results are presented of the absolute calibration of X-ray optical elements (diffraction gratings and Sc/Si multilayers) and detectors (an УΦ-4 photographic film and a vacuum X-ray diode) used in diagnostic devices to study generation of X-ray laser radiation in an argon plasma of a capillary discharge (λ = 46.9 nm). The measurements have been performed at the soft X-ray and vacuum UV station of the VEPP-4 storage ring at the Siberian International Center of Synchrotron Radiation. An absolutely calibrated AXUV 100G photodiode has been used as a reference detector. The relative error of calibration is 10%. The measured reflectances of the multilayer mirrors and gratings are in good agreement (within the limits of errors) with the results of their calibration at the RKK-1-100 X-ray calibration facility.

Tensor asymmetry of π−-meson photoproduction on polarized deuterons

The tensor asymmetry of exclusive π−-meson photoproduction on polarized deuterons was investigated. The T20 and T22 components of the reaction analyzing power contribute to the measured asymmetry. The detector made it possible to record two outgoing protons in coincidence in the range of polar angles θ1,2 = 44° − 88° and in the momentum range p1,2 = 350 − 700 MeV c−1. The measurements were performed at the VEPP-3 storage ring (Novosibirsk) using an internal target. The experimental results are compared with theoretical calculations.

A detector for imaging of explosions on a synchrotron radiation beam

Synchrotron radiation (SR) offers a unique chance to study the structure of a substance in fast processes. Since SR is emitted by electron bunches in a storage ring, the SR burst corresponding to a single bunch may be very short. Should a detector capable of detecting SR from a single bunch without mixing signals from different bunches be available, it is possible to obtain information on changes in the state of the material in a sample under investigation with a very high time resolution. A detector for imaging of explosions on an SR beam—DIMEX—has been developed by the Budker Institute of Nuclear Physics (Siberian Division of the Russian Academy of Sciences, Novosibirsk). This detector is a high-pressure ion-ization chamber with a strip readout at a pitch of 0.1 mm. The electron component of primary ionization is collected within 50 ns, which is substantially shorter than the orbital period of a bunch in the VEPP-3 storage ring (250 ns). The DIMEX is filled with a Xe—CO2 mixture (3: 1) at an absolute pressure of 7 atm. The spatial resolution of the detector is ∼210 µm, and its efficiency for radiation with an energy of 20 keV is ≥50%. The dynamic range of the detector is ∼100, which allows one to measure the signal with an accuracy of ∼1%. In this case, the maximum flux of X-ray photons, at which the DIMEX operates in a linear region, is ∼1010 photons/(channel s). Today, the detector has been used in experiments aimed at studying evolution of the density in detonation waves and processes of nanoparticle production at the VEPP-3 storage ring by employing the small-angle X-ray scattering technique.

Tests of Model of Absolute Measuring Instrument of Synchrotron Radiation Power

A model of absolute measuring instrument of power of synchrotron radiation in soft X-ray range of wavelengths of 8 – 0.4 nm based on high-temperature superconductor bolometer with electrical substitution has been developed, fabricated and tested. Tests have been carried out at the synchrotron radiation (SR) station “Cosmos” on the VEPP-4 storage ring of Budker Institute of Nuclear Physics of the SB RAS. It was ascertained that sensitivity of the device allows carrying out measurements of an SR flux power in the given spectral range. The minimum measured power was 3.2 W. A predicted threshold sensitivity of bolometer ~10-10 W/Hz1/2 at modulation frequency of 10 Hz and analysis of other factors influencing the measurement accuracy prove it to be real to achieve a 1 % accuracy at measurement of SR flux power of about 1 W.

Preliminary characterization of semiconductor detectors in the soft X-ray range using synchrotron radiation from the VEPP-4 storage ring

A photodiode developed at the Ioffe Physico-Tech nical Institute (St. Petersburg) and referred to in the literature as the SPD has been preliminarily calibrated by the primary-detector-based method. The possibility of application of SPD photodiodes as radiometric detectors has been investigated. The AXUV-100 photodiode (IRD Inc., United States) was used as a primary detector. The radiation strength of both detectors has been tested. It was revealed that, being more radiation-resistant, the SPD had radiometry characteristics that were not worse than those of the AXUIV-100.

Equipment for investigations of biological nanostructures by diffraction methods using synchrotron radiation

This paper reports on the experimental and methodical developments intended for the small-angle time-resolved station DICSI (“diffraction movie“) at the K1.3a beamline of the Siberia-2 storage ring at the Russian Research Centre “Kurchatov Institute.“ The principles of operation of the optical geometric and detecting systems, as well as the control and recording system, as applied to the investigation of the dynamics of biological nanostructures, have been considered in detail. A new version of the two-coordinate detecting system based on the designed highly effective fluorescent screen (Gd2O2S: Tb) and a CSDU-429 digital camera has been developed. The advantage of this recording system over the Image Plate detecting system in phenomenological investigations is that the optical images obtained on X-ray fluorescent screens with the use of cooled CCD/CMOS arrays can be directly entered into a computer. The detecting system has been tested on different samples by small- and wide-angle X-ray diffraction methods with the use of synchrotron radiation of the VEPP-3 storage ring at the Siberian Synchrotron Center (Novosibirsk, Russia) and the Siberia-2 storage ring at the Kurchatov Center for Synchrotron Radiation and Nanotechnology (Moscow, Russia). Different modifications of original two-coordinate recording systems have been used in systematic studies of the structural dynamics of biological tissues.