TRIUMF resonant ionization laser ion source

The range of isotopes available at the TRIUMF Isotope Separator Accelerator (ISAC) facility has been greatly enhanced by adding a Resonance Ionization Laser Ion Source (RILIS). A large wavelength range is accessible with the fundamental, second and third harmonic generation of titanium-sapphire laser light. In addition a dedicated laser is available for non-resonant laser ionization. The first on-line beam ⁶²Ga was delivered in Dec. 2004. In general RILIS improves the intensity, purity and emittance of ion beams. ⁶²Ga and ²⁶Al and Be beams have been delivered so far on-line. This work was financed by TRIUMF which is federally funded via a contribution agreement through the National Research Council of Canada.     

无机酸洗脱对胜利褐煤微晶结构及其自燃倾向性的影响

利用XRD、Raman、XPS和FT-IR表征技术,研究无机酸洗脱(HCl、H2SO4、HCl-HF)处理的胜利褐煤微晶结构的变化,采用自行设计的表面吸附仪-GC联用装置,对样品进行不同温度的低温脉冲氧化实验,考察了煤样在不同温度下氧吸附量的变化规律,通过低温脉冲氧吸附规律与TG/DTG和固定床燃烧实验关联,考察了煤样的自燃倾向。结果表明,无机酸洗脱对矿物质的脱除使得煤结构的有序度增加,石墨化程度提高,无机酸洗脱煤样与原煤相比吸氧量明显下降。随着吸附温度的升高,各煤样吸氧量明显增加,且随着脱除矿物质程度的增加,吸氧量呈减小的趋势,导致自燃倾向降低。     

Collocation Methods for Weakly Singular Second-kind Volterra Integral Equations with Non-smooth Solution

Collocation type methods are studied for the numerical solutionof the weakly singular Volterra integral equation of the secondkind: where the solution (t) is assumedto have the form f(t) = x(t)+r^?(t), x and being sufficientlysmooth. The solution is approximated near zero by a linear combinationof powers of t?, and away from zero by the usual polynomialrepresentation. Convergence is proved and many numerical experimentsare carried out with examples from the literature. A comparisonis made with a method of Brunner & Norsett (1981), originallydeveloped for (1) with a smooth solution. Special attentionis paid to the numerical approximation of the so-called momentintegrals which emerge in the collocation scheme.     

First results from the CRIS experiment

The ability to study rare isotopes with techniques such as mass spectrometry and laser spectroscopy is often prevented by low production rates and large isobaric contamination. This has necessitated the development of novel beam cleaning techniques that can efficiently isolate the isotope of interest. The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, achieves this by resonantly ionizing a bunched atom beam in a region of ultra high vacuum. This method is motivated by the need to measure the hyperfine structure and isotope shift at the extremes of isospin where typical production rates drop to 1 atom/s. The technique also offers the ability to purify an ion beam and even select long-lived isomeric states (> 1 ms) from the ground state, which can be subsequently studied by decay spectroscopy or mass spectrometry experiments. This paper will report on the successful commissioning of the CRIS beam line and the recent laser spectroscopy results and laser assisted nuclear decay spectroscopy on the neutron deficient francium isotopes.     

Early onset of ground state deformation in neutron deficient polonium isotopes

In-source resonant ionization laser spectroscopy of the even-A polonium isotopes (192-210,216,218)Po has been performed using the 6p(3)7s (5)S(2) to 6p(3)7p (5)P(2) (λ=843.38 nm) transition in the polonium atom (Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope shifts in (200-210)Po with a previous data set allows us to test for the first time recent large-scale atomic calculations that are essential to extract the changes in the mean-square charge radius of the atomic nucleus. When going to lighter masses, a surprisingly large and early departure from sphericity is observed, which is only partly reproduced by beyond mean field calculations.     

26 Al beam production by a solid state laser ion source at TRIUMF

Many experiments carried out at radioactive beam facilities require the production of intense, isotopically clean and isobar free beams of a particular isotope. At TRIUMF the addition of a resonant ionization laser ion source (TRILIS) enables a multitude of new beams and therefore new experiments to be carried out. ²⁶Al was one of the first radioactive ion beams delivered to an experiment using TRILIS. This paper outlines the development of the ²⁶Al ion beam for nuclear astrophysics.      

An approximate treatment of scattering based on the delta boundary operator

The development of a scheme to treat two-dimensional electromagneticscattering by electrically large, perfectly conducting bodiesis described. It incorporates the effects of surface curvatureand non-local phenomena and has the potential to provide thebasis for a general technique yielding more accurate predictionsthan the widely used physical optics method.     

First sulphinato and sulphonato representatives in the metalloporphyrinic series: alkyl(aryl)sulphinato- and -sulphonato-indium(III) porphyrins

The insertion of sulphur dioxide between the indium atom and the alkyl(aryl) group bonded to the metal, leads to sulphinatoindium(III)porphyrins. The sulphinato derivatives can easily be oxidized to the corresponding sulphonato compounds. The photochemical oxidation of thioalkyl(aryl)indium(III)porphyrins also gives rise to alkyl(aryl)sulphinato- and -sulphonato-indium(III)porphyrins. The structure of methylsulphonatoindium(III)tetraphenylporphyrin has been established by X-ray diffraction.     

Pentacoordinate iron(III) porphyrin carboxylates: Synthesis,physicochemical characteristics and x-ray crystal structure of acetato(5, 10, 15, 20-tetraparatolylporphyrinato) iron(III)

Carboxylatoiron(III) porphyrins have been synthesised by the action of carboxylic acids on the [(por)Fe]₂O dimers. ¹H NMR and ESR data of the isolated products are in accordance with pentacoordinate high spin 5/2 ferric complexes, the iron atom being displaced out of the plane of the porphyrin ligand. IR spectra show ν(CO) and ν(CO) bands separated by 356–409 cm^?1. The magnitude of this separation suggests coordination between the metal centre and the carboxylate group via one oxygen atom. Magnetic susceptibility measurements from 5 to 120 K lead to the value of μ = 5.88 B.M.. The X-ray structure of acetato (5, 10, 15, 20-tetra p-tolyporphyrinato) iron(III) confirms the above deductions. (tp MePP) Fe(CO₂CH₃). 0.5 CH₃COOH crystallises in the I2/c space group with unit cell parameters a = 24.464(8), b = 9.332(3), c = 37.174(4) Å, β = 90.49(2)°, V = 8485 ų, D_c = 1.27 g · cm^?3 and Z = 8. The crystal structure was refined to a conventional R(F) = 0.0584 and R_w(F) = 0.0653 for 5132 unique reflections with F₀ > 3σ(F₀). The iron atom is pentacoordinated by the four nitrogen atoms and one oxygen atom of the acetate group. It lies at 0.520(1) Å out of the porphinato plane and 0.485(1) Å out of the four nitrogen plane. The FeO bond length is 1.898(4) Å.