0000000000347200
AUTHOR
J. ÄRje
Discovery of New Fission Product Activities in the A=110–118 Mass Region
Neutron rich nuclei around the mass A=100 have recently attracted both theoretical and experimental interest since they are expected to form a new region of strong deformation. In contrary, very little experimental information is available in the adjacent transitional region A= 110–118. Due to expected isomerism in this region both low and high spin states can be studied via beta decay in many nuclei. The studies of these nuclides have many experimental difficulties. They are only weakly produced in thermal neutron induced fission and because all the elements in this mass region (Tc, Ru, Rh, Pd) have very high melting points they have not been available as beams of on-line isotope separator…
Helium-jet ion guide for an on-line isotope separator
Abstract A new method based on helium-jet techniques permits primary recoil ions produced in radioactive decay or in nuclear reactions to be run directly through a mass separator. Test results with a 227 Ac source give promise of qualities complementary to those obtained with conventional ion sources. This, 69 ± 5 per cent of the recoil particles transported with pure, commercial helium are positive ions, and 66 ± 5 per cent of them are mass separated. Nearly equal efficiencies are expected for most chemical elements and compounds. The mass spectra are remarkably free from groups caused by impurities. The shortest achievable separation time is estimated to be of the order of one millisecond.
The effect of magnetic field strength on the time evolution of high energy bremsstrahlung radiation created by an electron cyclotron resonance ion source
Abstract An electron cyclotron resonance (ECR) ion source is one of the most used ion source types for high charge state heavy ion production. In ECR plasma the electrons are heated by radio frequency microwaves in order to provide ionization of neutral gases. As a consequence, ECR heating also generates very high electron energies (up to MeV region) which can produce a vast amount of bremsstrahlung radiation causing problems with radiation shielding and heating superconducting cryostat of an ECR ion source. To gain information about the time evolution of the electron energies in ECR plasma radial bremsstrahlung measurements were performed. JYFL 14 GHz ECR ion source was operated in pulsed …
Status report of the SARA IGISOL used in the study of the 238U(α 40 MeV, ƒ) reaction
Abstract A new ion guide isotope separator on-line (IGISOL), operating with the SARA facility, has been constructed. Using the 238U(α 40 MeV, ƒ) reaction to produce very neutron-rich radioisotopes, all mass chains from A = 96 to 122 have been scanned by conventional methods of nuclear spectroscopy. Provided the stopping volume is separated from the primary beam, it has been proved that the yield is nearly proportional to the He pressure. In addition to the usual advantages (quasi-independence from physical and chemical properties of elements), this makes IGISOL a powerful technique for high energy recoil products. During the experiments the boundary of known neutron-rich nuclei was reached …
Separation of fission products by the ion guide fed isotope separator, IGISOL
Abstract The performance of the ion guide method in the on-line mass separation of fission products has been investigated. Activity was produced by bombarding nat. U targets with a beam of 20 MeV protons. All the mass chains from A = 95 through A = 120 have been scanned using conventional methods of nuclear spectroscopy. No chemical selectivity in the separation was observed; isotopes of highly nonvolatile elements from yttrium to palladium were produced with efficiencies equal to those for the more volatile ones. The boundary of known neutron-rich nuclides was reached throughout the mass region from A = 106 to A = 118. During the course of this preliminary study the new isotope 116 Rh was …
Production of titanium ion beams in an ECR ion source
Abstract Intensive highly charged Ti ion beams were successfully produced in the 14 GHz ECR ion source at the Accelerator Laboratory, University of Jyvaskyla (JYFL). The Ti beams were produced using the MIVOC technique, i.e. by allowing the vapor of an organic compound containing titanium to diffuse into the ion source at room temperature. After optimizing the source parameters the intensity of the 48 Ti 11+ ion beam reached a value of 45 μA.
The ion-guide isotope separator on-line at the Tohoku University Cyclotron
Abstract The status of the ion-guide isotope separator on-line at the Tohoku University Cyclotron is reported. The optimum ion-guide parameters were determined from test experiments using atomic and molecular ions ionized with an electric discharge inside the target chamber as well as using 64 Ga(T 1 2 = 2.6 m ) ions produced by the 64Zn(p, n) reaction. Using the present system together with a ΔE−E plastic counter telescope and a germanium detector we identified 16 short-lived nuclei including the first mass-separated nuclei 57Cu and 45V. The efficiency of mass separation for 64Ga was ϵ ∼ 1%, where ϵ is defined as the number of atoms collected at the end of the separator divided by that rec…
Submillisecond On-Line Mass Separation of Nonvolatile Radioactive Elements: An Application of Charge Exchange and Thermalization Processes of Primary Recoil Ions in Helium
Transportation of thermalized primary recoil ions from nuclear reactions by helium flow has been investigated as a means of injecting short-lived radioactive nuclides into an on-line isotope separator. Several short-lived radioactive isotopes of highly nonvolatile elements such as B, Sc, Nb, and W have been separated. The efficiency for heavy nuclides with half-lives above 1 ms is between 1 and 10%. The shortest-lived activity identified in an on-line separation is the 182-\ensuremath{\mu}s isomeric state in $^{207}\mathrm{Bi}$.
Half-life and configuration of the 1/2+ intruder state in203Bi
The decay properties of theJπ=1/2+,Eexc=1,098 keV state in203Bi were studied. The state was populated via the204Pb(p, 2n) reaction and the activity was studied with the ion guide isotope separator on-line system IGISOL. The half-life of the 1/2+ state was measured to beT1/2=303 ±5 ms. From this value the partial half-lives of the three depopulating branches 1/2+ →7/2− (E3), 1/2+→5/2− (E3 +M2) and 1/2+→9/2 g.s. − (M4) were deduced. Since all the transitions are configuration forbidden in first order, a detailed study of second-order shell-model configuration mixing could be performed.
Production of a magnesium ion beam using the MIVOC method
Abstract We report the successful production of multiply charged Mg ion beams at the Jyvaskyla ECRIS using a magnesium compound, magnesocene. The compound was placed in a separate vacuum chamber connected to the second stage of the 6.4 GHz JYFL-ECRIS. From there the vapour of the compound was allowed to diffuse into the source at room temperature. After a brief optimizing procedure the intensity of the 24 Mg 5+ beam was measured to be 11.8 eμA.
The first results with the new JYFL 14 GHz ECR ion source
Abstract A new 14 GHz ECR ion source has been built for the Accelerator Laboratory in the Department of Physics (JYFL), University of Jyvaskyla. This source belongs to the family of the LBNL AECR-U-based ECR ion sources. The operation during the first four months has shown that the new ion source performs well and is able to produce intensive highly charged ion beams. For example, 145 μA of O7+ ion beam was recorded. The production of iron and boron ion beams was tested using the MIVOC method. The 56Fe11+ ion beam current reached a value of 115 μA. The intensities of 11B3+ and 11B5+ ion beams were 235 and 52 μA, respectively. This iron beam intensity is the second highest and the boron beam…
Production of highly charged metal ion beams from organic metal compounds at RIKEN 18 GHz ECRIS
Abstract Intense beams of highly charged metal ions (e.g., 80 μA for Fe13+) are successfully extracted from the 18 GHz ECR Ion Source at RIKEN by feeding vapors of organic metal compounds at room temperature into the ECR plasma chamber: by MIVOC method. The beam intensity of particular metal ion is strongly dependent on the microwave power and served compounds.
A study of a helium-jet ion guide for an on-line isotope separator
Abstract A new method based on helium-jet techniques permits primary recoil ions, produced in radioactive decay or in nuclear reactions to be run directly through a mass separator. Results obtained with a 227 Ac source promise qualities complementary with those obtained with conventional ion sources and indicate an overall efficiency of the order of 10%. Preliminary results with 20 Na recoils from the 20 Ne(p,n)-reaction indicate that most of the ionic species transported out from the target chamber are negatively charged.
The effects of beam line pressure on the beam quality of an electron cyclotron resonance ion source
The results of a series of measurements studying the possibility to use neutral gas feeding into the beam line as a way to improve the quality of the heavy ion beams produced with an electron cyclotron resonance ion source (ECRIS) are presented. Significant reduction of the beam spot size and emittance can be achieved with this method. The observed effects are presumably due to increased space charge compensation degree of the ion beam in the beam line section between the ion source and the analyzing magnet. This is the region where the neutral gas was injected. It is shown that the effects are independent of the ion source tuning. Transmission measurements through the beam line and K-130 c…
Metal ion beams from an ECR ion source using volatile compounds
Abstract A new MIVOC method (Metal Ions from Volatile Compounds) at an ECR ion source gives a means to produce highly charged metal ion beams at room temperature conditions. Chemical compounds containing metallic atoms are utilized. The compound has to fulfill the two basic requirements: Vapour pressure of the compound is relatively high at room temperature. Evaporation and diffusion of the compound into the source take place without dissociation of the molecule. Up to present metal ion beams from iron and nickel compounds have been produced. The maximum currents of 56Fe9+ and 58Ni10+ from natural elements were 23.9 μA and 18.7 μA, respectively. First measurements have demonstrated the abil…
IBSIMU: a three-dimensional simulation software for charged particle optics.
A general-purpose three-dimensional (3D) simulation code IBSIMU for charged particle optics with space charge is under development at JYFL. The code was originally developed for designing a slit-beam plasma extraction and nanosecond scale chopping for pulsed neutron generator, but has been developed further and has been used for many applications. The code features a nonlinear FDM Poisson's equation solver based on fast stabilized biconjugate gradient method with ILU0 preconditioner for solving electrostatic fields. A generally accepted nonlinear plasma model is used for plasma extraction. Magnetic fields can be imported to the simulations from other programs. The particle trajectories are …
First intense isotopic titanium-50 beam using MIVOC method
Abstract An organometallic compound isotopically enriched in titanium-50 has been successfully used for the first time to produce intense ion beams with an ECR ion source by means of the MIVOC method. After some fruitful tests performed with compounds produced at IPHC Strasbourg with natural titanium, enriched organometallic titanium compound was produced successfully, beam extracted from ECR ion sources and accelerated through a K = 130 MeV cyclotron to an energy of 242 MeV. This isotopic 50 Ti 11 + beam was used for the first time in three week-experiment with typical MIVOC stable operating conditions. After optimization, up to 19.4 μA of titanium-50 in charge state 11 + could be extracte…