The development of a TESLA recirculator with superconducting accelerating structures in Ukraine

The recirculator project, which is to be built at the National Science Center, Kharkov Institute of Physics and Technology (NSC KIPT), is presented. The basic solutions incorporated in the design are given. The TESLA superconducting section is chosen as the accelerating structure of an accelerating complex. The text was submitted by the authors in English.     

DC-60 heavy ion cyclotron complex: The first beams and project parameters

The construction of the DC-60 Heavy Ion Cyclotron for the Interdisciplinary Scientific Research Complex (ISRC) in Astana started in early 2004. The cyclotron was manufactured and tested at the Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna. The main units were delivered to Astana and assembled in the ISRC building in the summer of 2006. The cyclotron was turned on in September, 2006. The first heavy ion beams in the whole A/Z and energy ranges were accelerated and extracted in December, 2006. The complex, based on the DC-60 cyclotron, is intended for applied and fundamental research using accelerated heavy ion beams ranging from Carbon to Xenon with energies in the range of 0.34–1.77 MeV/nucleon, as well as for experiments on the channel of low energy ion beams, where the ion extraction voltage supplied by the ECR source reaches 25 kV. The energy variation of the accelerated ions is accomplished by changing the ion charge. The possibility of smoothly tuning the ion energy by ±30% of its nominal value can be seen by changing the cyclotron magnetic field. Within the framework of commissioning the DC-60 cyclotron, a number of experiments were carried out with accelerating charged particle beams in the main points of the working diagram

DAΦNE status and upgrade plans

The Frascati Φ-factory DAΦNE has successfully completed experimental runs for the three main detectors, KLOE, FINUDA and DEAR. The best peak luminosity achieved so far is 1.6 × 10³² cm⁻² s⁻¹, while the best daily integrated luminosity is 10 pb⁻¹. At present the DAΦNE team is preparing an upgrade of the collider based on the novel crab waist collision scheme. The upgrade is aimed at pushing the luminosity towards 10³³cm⁻²s⁻¹. In this paper we describe present collider performance and discuss ongoing preparatory work for the upgrade. for DAΦNE Collaboration Team [1] The text was submitted by the author in English.     

VEPP-2000 collider commissioning

Construction of the VEPP-2000 construction was completed at the end of 2006. The first beam was captured in a special regime without final focus solenoids. In this regime, all systems of power supplies and machine control were calibrated and tuned. In the same mode vacuum chamber treatment by synchrotron radiation was performed with an electron beam current of up to 150 mA. The first test of the round beam option was performed at an energy of 508 MeV with a solenoidal field of 10 T in two straight sections of interaction. The text was submitted by the author in English.     

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.     

ILC activity at JINR

JINR is an active participant in the massive new international project ILC. JINR physicists are taking part in several fields of activity in the International Linear Collider (ILC), such as work on the photo injector prototype, the design and construction of cryomodules, laser metrology, cryodiagnostics, etc. The Joint Institute is one of the potential candidates for hosting the ILC, near Dubna, Russia. The status and progress of the above topics are discussed in the report. The text was submitted by the authors in English.     

The use of linear superconducting electron accelerator for subcritical reactor driving

At the National Science Centre, Kharkiv Institute of Physics and Technology (NSC KIPT) the possibility of creating an installation with a subcritical reactor driven by an electron accelerator is examined. To obtain the maximal stream of neutrons from a neutron-producing target at a minimal density of energy emission, the electron energy should be in the range of 100–200 MeV and the size of the target should be as large as possible. Other important requirements are beam continuity with time and long-term stability of the accelerator parameters. The variants of using the superconducting linear accelerator on the basis of a TESLA accelerating structure as of subcritical reactor driver are considered. The basic design parameters and characteristics of this installation are presented. The text was submitted by the authors in English.     

Beam dynamics study in the C235 cyclotron for proton therapy

A study of the beam dynamics in the C235 (T06) cyclotron made for proton therapy is presented. Results of the computer simulations of the particle motion in the measured magnetic field are given. A study of the resonance influence on the acceleration process was carried out. The corresponding tolerances on the magnetic field imperfections and transverse beam parameters were defined using these simulations. The text was submitted by the authors in English.     

Positron emission isotope production cyclotron in DLNP JINR (Status Report)

A C10-cyclotron for radioisotope production is under construction at the Dzhelepov Laboratory of Nuclear Problem, Joint Institute for Nuclear Research (DLNP JINR). It is a compact isochronous cyclotron for accelerating H⁻ ions to the energy of about 10 MeV. The magnetic system, vacuum chamber and accelerating system is being built now. Results of the calculation and forming of the cyclotron magnetic field and the study of the beam dynamics from an ion source to an extraction system in calculated magnetic field are presented. The text was submitted by the authors in English.     

Magnet design and beam dynamics in computed fields for the DC-350 cyclotron

The DC-350 is an isochronous cyclotron designed in the Flerov Laboratory of Nuclear Reaction (FLNR). It is intended for accelerating ions with a mass-to-charge ratio A/Z within an interval of 5–10 and with an energy of 3–12 MeV/u at the extraction radius. These ion beams will be used in nuclear and applied physics experiments. The paper describes the results of a 3D magnet simulation. The cyclotron magnet and IM90 analiziting-bend magnet of the axial injection channel are studied here. The influence of correction coils on the cyclotron magnet is calculated. All magnet fields were calculated by MERMAID 3D code [1]. The text was submitted by the authors in English.     

Adiabatic theory of particle trapping due to Coulomb crossing of one-dimensional betatron resonance

In the presence of space charge forces, synchrotron oscillations result in periodic modulation of the space charge tune shift, periodic crossing of betatron resonances, and particle trapping in resonance islands. The trapping effect for one-dimensional resonance is considered using classical perturbation theory and the “frozen core” approach to calculation of space charge forces. The beam losses and emittance growth are analyzed for arbitrary order resonance; the numerical results are given for the third-order resonance. The text was submitted by the authors in English.     

Flattop operation of the ILC accelerating cryomodule

A 500 GeV center-of-mass International Linear Collider (ILC), currently under R&D development, is foreseen as the next-generation high-energy physics (HEP) instrument [1]. The achievement of a 31.5 MV/m average operational accelerating gradient in a single cryomodule is a proof of principle for the ILC project. However, individual cavity performance may have a large spread in operating gradients, up to 20% of the nominal value [2, 3]. In case of cavities performing below the average, the design parameters could be achieved by tweaking the RF distribution accordingly. We present a simple theoretical analysis of the ILC cryomodule operation with a gradient spread. The difference in the gradients breaks the synchronism of a transient processes in each cavity and causes nonuniform acceleration along the bunch train. A proper solution was found to maintain flattop operation of the accelerating module. Finally, we perform numerical efficiency estimations for the proposed RF distribution scheme based on real data of the gradient spread of actual cavities. The text was submitted by the authors in English.     

An IC100 cyclotron based facility for producing nuclear filters and for scientific and applied research

The cyclotron IC-100 station, based on the Laboratory of Nuclear Reactions (JINR, Dubna, Russia), provides the industrial construction of nuclear filters. During modernization, the cyclotron was equipped with a superconducting ECR-ion source and an axial injection system. The specialized beam channel with a two coordinate scanning system and equipment for irradiating polymer films was installed in the implantation part of the station. High intensity heavy ion beams of Ne, Ar, Fe, Kr, Xe, I, and W have been accelerated to 1 MeV/nucleon energy. The investigation into irradiated crystals features and irradiation of different polymer films is provided. Also, a few thousands square meters of track films with holes in the wide range of densities were produced. The cyclotron-based station is capable of solving different kinds of scientific and applied problems as well. The text was submitted by the authors in English.     

Investigations of electron beam characteristics using an accelerator based on a magnetron gun with a secondary-emission cathode

The reliability and service life of accelerating installations are substantially determined by the lifetime of electron sources. The accelerator under consideration has a magnetron gun with a channel-free cold secondary-emission cathode in crossed fields as an electron source [1, 2]. In the present work, the data of the electron beam parameters obtained in the accelerator based on the magnetron gun with a secondary-emission cathode are given, and possible secondary uses are suggested. The text was submitted by the authors in English.     

On the role of secondary interactions in the production of bremsstrahlung spectra from a thick target

Bremsstrahlung emission, or radiation loss, is the dominant mechanism of energy dissipation of electrons at relativistic energies greater than a few MeV when it is subjected to acceleration in the field of the nucleus or of the electrons. In this study, the Monte Carlo calculations for bremsstrahlung spectra have been described for the case of a thick tungsten target with incident electron beams from 10 to 50 MeV, where secondary interactions induced by the electrons and photons in the target, such as energy loss, absorption, scattering, and (e ⁺, e ⁻)-pair production effects, were taken into account. The text was submitted by the authors in English.     

Time-dependent exactly solvable models for quantum computing

A time-dependent periodic Hamiltonian admitting exact solutions is applied to construct a set of universal gates for a quantum computer. The time evolution matrices are obtained in an explicit form and used to construct logic gates for computation. A way of obtaining an entanglement operator is discussed, too. The method is based on transformation of soluble time-independent equations into time-dependent ones by employing a set of special time-dependent transformation operators. The text was submitted by the authors in English.     

Sound absorption by a solution of nanoparticles

Absorption of an acoustic wave in a colloidal solution via two mechanisms: due to viscous friction in the liquid and due to energy dissipation on nanoparticles is studied. The dependence of the imaginary part of the wave vector on the frequency is estimated in both cases. It is shown that in typical colloidal solutions, the first absorption mechanism dominates at low frequencies, and the second one, at higher, ultrasonic frequencies.     

Formation of mixed clusters in a pulsed supersonic helium-oxygen-isoprene jet

An experimental study of the formation of mixed van der Waals oxygen-isoprene complexes, generated in an expanding supersonic helium-oxygen-isoprene jet at various stagnation pressures and at diverse oxygen and isoprene concentrations, has been performed. To measure the composition and distribution of the partial densities of the individual components, molecular beam mass spectrometry was adapted to pulsed modes of gas source operation. The particularities of applying mass spectrometry to studying clustered isoprene streams in a pulsed mode have been discussed. The composition of small clusters generated in a free supersonic jet has been checked for dependencies upon the initial mixture composition and stagnation pressure. The mechanism of nucleation has been identified for different partial concentrations of impurities in the helium stream. It has been shown that, even at a 0.3% concentration of isoprene in the mixture, nucleation starts with the formation of hydrocarbon complexes. The specific features of the dissociative ionization of van der Waals complexes, consisting of pure isoprene and mixed complexes, have been discussed. The conditions needed for the formation of binary oxygen-isoprene van der Waals complexes have been identified.     

Growth of gas phase nanoparticles with an accretion mechanism

Nano-droplet growth in a supersaturated vapor has been investigated in a gas aggregation source using laser-ionization time-of-flight mass spectrometry. During its propagation into an atomic vapor, a small particle grows by sticking atoms on its surface. This accretion process has been highlighted through the clustering of homogeneous particles M_n and heterogeneous M_n(M₂O) and M_n(MOH)₂ particles in a metallic vapor and a helium buffer gas (M = Na or K). A modelization is introduced so as to connect the measured cluster mass distributions to the pertinent physical parameters. The mass distribution width is particularly sensitive to the efficiency of the first steps in the growth sequence. We used this property to compare the ability of this vapor-condensed matter phase transition to occur around various homogeneous and heterogeneous nucleation seeds.