Probing shapes of very neutron deficientZ≈82 nuclei using the recoil-decay tagging method

The JYFL gas-filled recoil separator, RITU, combined with efficient Ge-detector arrays has been employed in in-beam γ-ray studies of very neutron-deficient nuclei close to theZ=82 shell. Gamma-rays from nuclei produced at the few μb cross-section level have been detected.     

Cluster research in Jyväskylä

A short overview of the ongoing nuclear-reaction program at the Department of Physics, University of Jyväskylä, is presented. Special emphasis is put on cluster phenomena investigated with the K=130 heavy-ion cyclotron, such as measurements of alpha-resonance states, rainbow scattering, and some special features in fusion-fission reactions. Relevant developments in detection techniques are mentioned, and the outlook for the possible continuation of the nuclear-reaction program in Jyväskylä is given.     

Nano ES GEMMA and PDMA,new tools for the analysis of nanobioparticles—Protein complexes,lipoparticles, and viruses

Differential mobility analysis (DMA) is a technique suited for size analysis as well as preparative collection of airborne nanosized airborne particles. In the recent decade, the analysis of intact viruses, proteins, DNA fragments, polymers, and inorganic nanoparticles was possible when combining this method with a nano-electrospray charge-reduction source for producing aerosols from a sample solution/suspensions. Mass analysis of high molecular weight noncovalent complexes is also possible with this methodology due to the linear correlation of the electrophoretic mobility diameter and the molecular mass. In this work, we present the analysis (size and molecular mass) of high molecular weight multimers (noncovalent functional homocomplex) of Jack bean urease in a mass range from 275 kDa up to 2.5 MDa, with mainly present tri- and hexamers but also higher oligomers of the 91 kDa monomer subunit. In a second experiment, the size analysis of intact very-low-density (approximately 35 nm), low-density ( approximately 22 nm) and high-density lipoparticles (approximately 10 nm), which are heterocomplexes consisting of cholesterol, lipids, and proteins in different ratios, is presented. Results from mobility analysis were in excellent agreement with particle diameters found in literature. The last presented experiment demonstrates size analysis of a rod-like virus and selective sampling of a selected size fraction of electrosprayed, singly-charged tobacco mosaic virus particles. Sampling and subsequent transmission electron microscopic investigations of a specific size fraction (40 nm electrophoretic mobility diameter) revealed the folding of virus particles during the electrospray and charge reduction (electrical stress) as well as solvent evaporation (mechanical stress) process, leading to an observed geometry of 150 (length) x 35 (width) nm (average cylindrical geometry of unsprayed intact virus 300 x 18 nm).     

Optical particle spectrometry—Problems and prospects

Optical particle counters and spectrometers have found broad use in aerosol and atmospheric research, air pollution studies and industrial particle monitoring. The utilization of the elastic scattering of light results in increasingly portable and cost effective instrumentation due to the ongoing miniaturization of building components such as light sources and detectors. However, the non-monotonic size dependence of scattered light intensity and its variability with the changing refractive index of particles influences the function of most single optical particle counters and spectrometers. This problem is a key issue still driving the development of these instruments, first introduced more than half a century ago. Ongoing progress has resulted in not only smaller but also more sophisticated and precise instruments, but the old weakness still remains—varying response to changes of the index of refraction of particles and non-monotonic response curves. Consequently, alternative approaches exploiting elastic scattering are presented here.     

Liquid-crystalline properties of 4-alkyl-, 4-alkyloxy and 4-halogene-4′-hydroxyazobenzene alkyloates

Twenty one esters, 4-alkyl-, 4-alkyloxy-, 4-nitro- and 4-halogene-4′-hydroxyazobenzne alkyloates have been synthesised. Basing on the DSC calorimetry and polarizing microscopy liquid- crystalline polymorphism was investigated. Five types of mesophases were identified: nematic, smectics A, C, F and unknown X (probably G).     

Conversion electron spectroscopy at IGISOL

Conversion elecron spectroscopy has been an important part of the nuclear spectrocopy research at the Department of Physics of the University of Jyväskylä since the commissioning of the first cyclotron in the mid 1970s. At the IGISOL facility a specialiced conversion electron spectrometer ELLI was developed in the late 1980s. The first results with ELLI were obtained using the beams from the old MC-20 cyclotron to study newly discovered isotopes of refractory fission products. In the present K130 cyclotron laboratory ELLI has been utilized in many decay-spectroscopy experiments both neutron-deficient and neutron-rich side of the valley of stability. In the early 2000s the new JYFLTRAP ion trap system overthrew ELLI from its permanent place in the IGISOL beamline. Conversion electron spectroscopy has continued with the new Penning trap that has been used in in-trap electron spectroscopy tests and post-trap electron spectroscopy is foreseen.     

Properties of the 13/2+ isomeric decay in201Hg

The isomeric decay of theT _1/2=94 us isomeric state in²⁰¹Hg was studied in beam via the reaction¹⁹⁸Pt(α, n). Gamma-ray and conversion-electron spectra were recorded. From the conversion coefficients, the multipolarities of the two depopulating transitions were determined to beM 2 + 10%E 3 andE 2, respectively. These assignments give the depopulating transitions to be 13/2⁺ → 9/2^? and 9/2^? → 5/2^?, and these thus substantiate the previous suggestion that the isomeric state hasJ ^π=13/2⁺. For the 13/2⁺ → 9/2^? M 2 transition a detailed study ofE 3 andM 4 admixed amplitudes was done. The microscopic properties of the 13/2⁺ and 9/2^? states are discussed, and a comparison to the corresponding ones in^199,203,205Hg is made.