[en] Monitoring of light-element concentration in steel is very important for quality assurance in the steel industry. In this work, detection in open air of trace phosphorus (P) in steel using laser-induced breakdown spectroscopy (LIBS) combined with laser-induced fluorescence (LIF) has been investigated. An optical parametric oscillator wavelength-tunable laser was used to resonantly excite the P atoms within plasma plumes generated by a Q-switched Nd:YAG laser. A set of steel samples with P concentrations from 3.9 to 720 parts in 10⁶(ppm) were analyzed using LIBS-LIF at wavelengths of 253.40 and 253.56 nm for resonant excitation of P atoms and fluorescence lines at wavelengths of 213.55 and 213.62 nm. The calibration curves were measured to determine the limit of detection for P in steel, which is estimated to be around 0.7 ppm. The results demonstrate the potential of LIBS-LIF to meet the requirements for on-line analyses in open air in the steel industry.

[en] Electron Cyclotron Resonance ion source (ECRIS), which produces singly to highly charged ions, is widely used in heavy ion accelerators and is finding applications in industry. It has progressed significantly in recent years thanks to a few techniques, such as multiple-frequency plasma heating, higher mirror magnetic fields and a better cold electron donor. These techniques greatly enhance the production of highly charged ions. More than 1 emA of He²⁺ and O⁶⁺, hundreds of eμA of O⁷⁺, Ne⁸⁺, Ar¹²⁺, more than 100 eμA of intermediate heavy ions with charge states up to Ne⁹⁺, Ar¹³⁺, Ca¹³⁺, Fe¹³⁺, Co¹⁴⁺ and Kr¹⁸⁺, tens of eμA of heavy ions with charge states up to Xe²⁸⁺, Au³⁵⁺, Bi³⁴⁺ and U³⁴⁺ were produced at cw mode operation. At an intensity of about 1 eμA, the charge states for the heavy ions increased up to Xe³⁶⁺, Au⁴⁶⁺, Bi⁴⁷⁺ and U⁴⁸⁺. More than an order of magnitude enhancement of fully stripped argon ions was achieved (I≥0.1 eμA). Higher charge state ions up to Kr³⁵⁺, Xe⁴⁶⁺ and U⁶⁴⁺ at low intensities were produced for the first time from an ECRIS

[en] A design study for the extraction system of the 3rd Generation super conducting ECR ion source at LBNL is presented. The magnetic design of the ion source has a mirror field of 4 T at the injection and 3 T at the extraction side and a radial field of 2.4 T at the plasma chamber wall. Therefore, the ion beam formation takes place in a strong axial magnetic field. Furthermore, the axial field drops from 3 T to 0.4 T within the first 30 cm. The influence of the high magnetic field on the ion beam extraction and matching to the beam line is investigated. The extraction system is first simulated with the 2D ion trajectory code IGUN with an estimated mean charge state of the extracted ion beam. These results are then compared with the 2D code AXCEL-INP, which can simulate the extraction of ions with different charge states. Finally, the influence of the strong magnetic hexapole field is studied with the three dimensional ion optics code KOBRA. The introduced tool set can be used to optimize the extraction system of the super conducting ECR ion source

[en] For the on-line production of a ¹⁴O⁺ ion beam, an integrated target-transfer line ion source system is now under development at LBNL. ¹⁴O is produced in the form of CO in a high temperature carbon target using a 20 MeV ³He beam from the LBNL 88'' Cyclotron via the reaction ¹²C(³He,n)¹⁴O. The neutral radioactive CO molecules diffuse through an 8 m room temperature stainless steel line from the target chamber into a cusp ion source. The molecules are dissociated, ionized and extracted at energies of 20 to 30 keV and mass separated with a double focusing bending magnet. The different components of the setup are described. The release and transport efficiency for the CO molecules from the target through the transfer line was measured for various target temperatures. The ion beam transport efficiencies and the off-line ion source efficiencies for Ar, O₂ and CO are presented. Ionization efficiencies of 28% for Ar⁺, 1% for CO, 0.7% for O⁺, 0.33 for C⁺ have been measured

[en] High charge states, up to fully stripped ¹¹C and ¹⁴O ion, beams have been produced with the electron cyclotron resonance ion sources (LBNL ECR and AECR-U) at Lawrence Berkeley National Laboratory. The radioactive atoms of ¹¹C and ¹⁴O were collected in batch mode with an LN₂ trap and then bled into the ECR ion sources. Ionization efficiency as high as 11% for ¹¹C⁴⁺ was achieved

[en] BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88'' Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88'' Cyclotron's Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min ¹¹C and 70-sec ¹⁴O, produced by (p,n) and (p, α) reactions on low-Z targets. A test program is currently being conducted at the 88'' Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial ¹¹C beams of up to 2.5x10⁷ ions/sec and ¹⁴O beams of 3x10⁵ ions/sec

[en] Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 deg. C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 deg. C is estimated up to 10 μm min^-1. High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices.

[en] Rapid single-step fabrication of graphene patterns was developed using laser-induced chemical vapor deposition (LCVD). A laser beam irradiates a thin nickel foil in a CH₄ and H₂ environment to induce a local temperature rise, thereby allowing the direct writing of graphene patterns in precisely controlled positions at room temperature. Line patterns can be achieved with a single scan without pre- or postprocesses. Surprisingly, the growth rate is several thousand times faster than that of general CVD methods. The discovery and development of the LCVD growth process provide a route for the rapid fabrication of graphene patterns for various applications.

[en] BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88'' Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88'' Cyclotron's Advanced Electron Cyclotron Resonance ion source. The first radioactive beams to be developed will include 20-min ¹¹C and 70-sec ¹⁴O, produced by (p, n) and (p, α) reactions on low-Z targets. Tests at the 88'' Cyclotron lead to projections of initial ¹¹C beams of 2x10⁸ ions/sec ¹⁴O beams of 1x10⁶ ions/sec. Construction of BEARS is expected to be completed in the spring of 1999