The DC-140 cyclotron complex now under construction at the Flerov Laboratory of Nuclear Reactions (FLNR) is designed for wide range of applied research using accelerated heavy ion beams, e.g., studying the radiation physics of solids, the development and production of track membranes (nuclear filters), and the radiation resistance of electronic components. To perform experiments, the accelerator must provide accelerated ion beams with two fixed energies: 2.1 MeV/nucleon and 4.8 MeV/nucleon in the mass range of Ne to Bi, with intensities of up to 1012 particles/s (for Xe ions) on the target. In accordance with the working diagram of DC-140 cyclotron, the ion source must provide ion beams with mass-to-charge ratios in the range A/Z = 5–8 (Ne4+–Bi38+).

The purpose of this work is to search for the optimal design and arrangement of magnets to ensure the correct and uniform distribution of the magnetic field in the plasma chamber of the electron cyclotron resonance (ECR) source, using the DECRIS-5M source as an example. In this paper we investigate the influence of external magnetic fields created by solenoids in the area of a hexapole magnet from the point of view of demagnetization, as well as the selection of materials to minimize this effect. Also, we consider the influence of the material choice on the service life of magnets. Numerical simulations were carried out using the COMSOL Multiphysics software package. In addition, we have carried out magnetic field measurements of the DECRIS-5M source hexapole magnet. The results can be used to improve the characteristics of existing ion sources and for development of the new sources.

The article describes the experiments carried out during last years at the accelerator complex DC-60 of Astana branch of the INP (Nur-Sultan, Kazakhstan Republic), to provide intense ion beams of metals with the use of volatile organometallic compounds (Metal Ions from Volatile Compounds) – MIVOC. As a result of performed work for the first time at DC-60 cyclotron a beams of nickel, iron, silicon, cobalt, chromium, titanium, germanium and hafnium ions were produced.

This article describes experiments for producing highly intense metal ion beams at the ECR source of the DC-60 cyclotron using the evaporation of organometallic compounds by the MIVOC method. As a result of the works, beams of nickel, cobalt, chromium, and silicon ions are obtained. The optimization of modes of acceleration for the ion beams to an energy of 1.75 MeV/n is carried out.

The mass, energy and angular distributions of binary fragments formed in the reactions 64Ni + 238U, 58Fe + 244Pu, 52Cr + 248Cm, 54Cr + 248Cm at energies near the Coulomb barrier have been measured. The analysis of energy distributions of the symmetric fragments with mass numbers $${{{{A}_{{{\text{CN}}}}}} \mathord{\left/ {\vphantom {{{{A}_{{{\text{CN}}}}}} 2}} \right. \kern-0em} 2} \pm 20$$ formed in these reactions have been applied to separate compound nucleus fission and quasi-fission. The estimated fusion probability for the reactions Cr, Fe, and Ni ions with actinide targets shows an exponential dependence on the mean fissility parameter of the system and shows also that reaction with Cr ions is more favorable for production of the super heavy element with Z = 120.

This paper describes recent results obtained with a compact 2.45 GHz ECR Ion Source at the ECR ion sources test bench. The source was tested for production of helium and hydrogen ions with different configurations of Ultra High Frequency (UHF) coupler, UHF power and frequency. At the extraction voltage about of 10 kV and UHF power about of 100 W more than 500 µA of He + ions were produced with the extraction hole of 3 mm in diameter that corresponds to the current density of 7.5mA/cm2. The future possible upgrades of the ion source are also discussed.

The results of experiments on the production of intense beams of heavy lithium, magnesium, phosphorus, and calcium ions with a microevaporator are reported. The first beams of 7Li, 24Mg, 31P, and 40Ca ions were produced in these experiments conducted in 2017–2018 at the DC-60 cyclotron. The modes of acceleration of these ions to an energy of 1.75 Mev/nucleon were also optimized.

In 2017-2018, research program of the DC-60 cyclotron (Astana Branch of the Institute of Nuclear Physics, Kazakhstan) requests acceleration of intense ion beams of solid elements. Beams of B and Fe ions are produced in ECR ion source by using the volatile compounds, while ions of Li, Mg, P and Ca are produced by evaporation from an oven. Beams of Fe-56(10+), Li-7(1+), Mg-24(4+), P-31(5+), Ca-40(7+), and B-11(2+) ions were accelerated up to energies of 1.32-1.75 MeV/u.

Received 23 January 2018DOI:https://doi.org/10.1103/PhysRevC.97.019904©2018 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionLow & intermediate energy heavy-ion reactionsNuclear fusionNuclear reactionsTransfer reactionsProperties190 ≤ A ≤ 219Nuclear Physics

Accelerated beams of metal ions are required for a series of scientific and technical tasks in the field of radiation physics of a solid state, for example, the only method for rapid assessments of the radiation damage investigation, the developed structural materials of nuclear technology is ion irradiation. The standard methods for production ion beams at ECR-sources from gas mixtures cannot fully meet the requirements of the experiment. To increase the spectrum of accelerated ions at the cyclotron DC-60 is working on developing methods of heating the solid substances to produce multiply charged ion beams of metals into an ECR ion source DECRIS-3. The article is dedicated to description of methods of production ion beams of metals in two ways: the direct injection of a substance into plasma and a method of heating the crucible with a working substance by micro-furnace. As a result of the work carried out on the DC-60 cyclotron, beams of lithium ions 6,7Li, 24Mg magnesium, 31P phosphorus and 40Са calcium were produced for the first time. Using these methods was produced beams of lithium ions 7Li1+ metal consumption of 1.1 mg/hour and derived a ion beam current of 500 µA, magnesium 24Mg4+ with the consumption of the substance 2.1 mg/hour and intensity of 81 µA, phosphorus consumption of substances 1.7 mg/hour at the beam current 31P5+ 60 µA and calcium 40Ca5+ with the consumption of a substance of 0.7 mg/hour when the beam current is 140 µA.

This paper presents the design of the DECRIS-PM ECR ion source developed for the DC-280 cyclotron under construction at FLNR JINR. The results of the ion-source testing are presented. Highintensity beams for gaseous (900 μA of Ar8+, 550 μA of Ar9+, 160 μA of Kr15+, etc.) and solid targets (450 μA of Mg5+, 220 μA of Ca9+, 90 μA of Ti9+, etc.) are produced during the testing.

This article describes experiments carried out in 2017–2018 at the DC-60 accelerator complex (Astana branch of the Institute of Nuclear Physics, Almaty, Kazakhstan) to develop methods for producing intense beams of multicharged iron and boron ions with the use of volatile organometallic compounds (Metal Ions from Volatile Compounds (MIVOC)). Beams of iron and boron ions were obtained for the first time on the DC-60 cyclotron, and the acceleration modes of 56Fe10+ and 11B2+ ions were optimized to energies of 1.75 and 1.5 MeV/n, respectively.

The synthesis of super heavy elements (SHE), in pursuit of the island of stability on the chart of the nuclei (around Z=114, N=184), is one of the major goals of today’s nuclear physics research. In order to synthesize SHE, fusion of two heavy nuclei is required. After the two fusing nuclei come into the contact configuration, the di-nuclear system may evolve in shape to either form a compact equilibrated heavy nucleus, called compound nucleus (CN), or decay into fission like event before forming a CN, known as quasi-fission. The competition between these two processes exhibits complex behaviour. The production of SHE in higher quantity or those which are yet to be discovered in the laboratory, requires understanding of the mechanism of dynamical evolution that the system undergoes after contact. The cross section for (super) heavy element formation via fusion evaporation is given by ER(Ecm)=capture(Ecm)× PCN(Ecm) × Psurvival(Ecm) where capture is the capture cross-section for the formation of the di-nucleus system in competition with other peripheral reactions. Psurvival is the survival probability of the ER which is determined by the competition between fission and neutron evaporation of the excited compound nucleus. PCN is the probability of complete fusion after the capture stage in the dinuclear system and is an important quantity that determines the fraction of quasi-fission which is believed to be the main culprit for the hindrance of SHE formation. The heaviest element that have been discovered till date is Z=118. Elements beyond Z=113 have been discovered only in hot fusion reaction with 48 Ca beam with actinides target. However, the production of elements beyond Z=118 requires beam heavier than Ca, as targets heavier than Cf are not available for the long duration synthesis experiments of SHE. Here we report the preliminary results of the experimental determination of capture and PCN for the SHE Flerovium (Z=114), produced in reactions with 52 Cr beam which is one of the probable candidates for the production of SHE beyond Z=118. The experiment was carried out at the U400 cyclotron at Flerov Laboratory of Nuclear Reactions, Russia. The target was 232 Th of thickness 280 μg/cm 2 on 12 C backing (35 μg/cm 2 ). Beam energies were chosen near the Coulomb barrier. The fragments were detected in coincidence by the double-arm time-of-flight spectrometer CORSET [1]. Each arm of the spectrometer consists of a compact start detector and a position-sensitive stop detector, based on microchannel plates. The data were analysed using standard two-body kinematics [1]. From the measured velocities and angles, the masses and kinetic energies of the reaction products, corrected for energy losses, were calculated.

Background: Low-energy multinucleon transfer reactions may be used for production of new neutron-enriched heavy nuclei. Purpose: Our aim is to investigate the influence of proton (Z = 82) and neutron (N = 82, 126) shells as well as orientation effects on the formation of reaction products in the inverse quasifission process in the reactions Gd-156,Gd-160 + W-186. Methods: Mass, energy, and angular distributions of primary binary fragments formed in the reactions Gd-156 + (186)Wat an energy of 878 MeV, and Gd-160 + (186)Wat 860 and 935 MeV, have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR), Dubna. Results: Enhancement in the yield of products with masses 200-215 u has been found for both reactions. The cross sections of the formation of trans-target fragments with masses around 208 u are found to be about 10 mu b at the Coulomb barrier energy and reach the level of 0.5 mb at the energy above the barrier for side-to-side collision. Conclusions: The enhanced yield of products with masses heavier than the target mass confirms the important role of the closed shells at Z = 82 and N = 82, 126 in the inverse quasifission process in low-energy damped collisions. The orientation effect caused by the strong deformation of colliding nuclei can result in a gain in the yield of heavy target-like fragments.

A high intensity ion beam of 50Ti ions was obtained using the ECR ion source on the U400 cyclotron. The experimental tests using accelerated 50Ti ions were performed with a modernized VASSILISSA separator (SHELS). Data has been obtained on the transmission coefficients of recoil nuclei synthesized in complete fusion reactions. Estimates from ion optical calculations performed in the design phase of the project of modernizing the separator are completely confirmed.

The production of metal ion beams by electron cyclotron resonance (ECR) ion sources using the MIVOC (Metal Ions from Volatile Compounds) method is described. The method is based on the use of metal compounds which have high vapor pressure at room temperature, e.g., C2B10H12, Fe(C5H5)2, etc. Intense ion beams of B and Fe were produced using this method at the FLNR JINR cyclotrons. Experiments on the production of cobalt, chromium, vanadium, germanium, and hafnium ion beams were performed at the test bench of ECR ion sources. Main efforts were put into production and acceleration of 50Ti ion beams at the U-400 cyclotron. The experiments on the production of 50Ti ion beams were performed at the test bench using natural and enriched compounds of titanium (CH3)5C5Ti(CH3)3. In these experiments, 80 μA 48Ti5+ and 70 μA 48Ti11+ beam currents were obtained at different settings of the source. Following successful tests, two 3-week runs were performed with 50Ti beams at the U-400 cyclotron aimed to perform experiments on the spectroscopy of superheavy elements. The intensity of the injected 50Ti5+ beam was 50–60 μA. The source worked stably during experiments. The compound consumption rate was determined at about 2.4 mg/h, which corresponded to the 50Ti consumption of 0.6 mg/h.