First observation of excited states in 184Pb: spectroscopy beyond the neutron mid-shell

Excited states have been identified for the first time in ¹⁸⁴Pb, the first even-even Pb isotope beyond the 82 < N < 126 mid-shell, using the recoil-decay tagging (RDT) technique. A collective band built on the first-excited 2⁺ state has been observed. This resembles those seen in ^186,188Pb and the Hg isotones, and can thus be associated with a prolate-deformed shape. Variable moment of inertia (VMI) fits of the prolate 0⁺ level energies in ^184,186,188Pb indicate that the minimum appears at N= 103, the same neutron number at which the corresponding minimum in Hg isotopes is observed. Received: 19 May 1998 / Revised version: 1 July 1998     

Alpha decay studies of neutron-deficient radium isotopes

Neutron-deficient isotopes of radium have been produced in the reactions ³⁵Cl + ¹⁷⁵Lu, ⁴⁰Ar + ^170,171Yb, and ³⁶Ar + ^170,171Yb and separated in-flight with a gas-filled recoil separator. The activities have been identified on the basis of correlated alpha decay chains. The alpha particle energy E_α and the half-life T_1/2 of an isomeric state of the new isotope, ^203mRa, have been determined to be (7615±20) keV and (33 _?10 ⁺²² ), respectively. An assignment of another decay with E_α = (7577±20) keV and T_1/2 = (1.1 _?0.5 ^+5.0 ) ms to ^203g Ra is made on the basis of one observed three-decay chain. Tentative evidence for the production of the new isotope ²⁰²Ra is also given. The values E_α = (7860±60) keV and T_1/2 = (0.7 _?0.3 ^+3.3 ) ms were measured. Improved decay data have been obtained for ²⁰⁴Ra. The results are E_α = (7484±10) keV and T_1/2 = (59 _?9 ⁺¹² ). Earlier findings concerning the decay of two states in ²⁰⁵Ra and an isomer in ²⁰⁷Ra have been confirmed. Approximate values for cross sections have been determined for ²⁰²Ra, produced using the ³⁶Ar + ¹⁷⁰Yb reaction and for ²⁰³Ra, ²⁰⁴Ra, and ²⁰⁵Ra using the ³⁵Cl + ¹⁷⁵Lu reaction. The results are 2 nb (²⁰²Ra), 4 nb (²⁰³Ra), 40 nb (²⁰⁴Ra), and 800 nb (²⁰⁵Ra).     

CdCr2Se4−CdCl2 phase diagram for the crystallization of semiconducting spinel CdCr2Se4 from high temperature solution

The part of the CdCr₂Se₄-CdCl₂ phase diagram within the range of 75–100 mole% of CdCl₂ has been examined. The composition CdCr₂Se₄ · CdCl₂ was found to be stable below 542°C. The crystallisation processes of CdCr₂Se₄ spinel for two mixture compositions: 88% CdCl₂-12% CdCr₂Se₄ and 80% CdCl₂-20% CdCr₂Se₄ have been carried out and the parameters of CdCr₂Se₄ crystal growth from the CdCl₂ flux were determined.     

Simple density topology

We introduce a new topology on the real line generated by the simple density points for measure. We show also that a simple category density point does not lead to a new notion. Supported by research project “Analisi Reale”, Italian PRIN funds Visiting Professor at Facoltà di Economia, Università Federico II, Naples, Italy     

Liquid phase separation of proteins based on electrophoretic effects in an electrospray setup during sample introduction into a gas-phase electrophoretic mobility molecular analyzer (CE–GEMMA/CE–ES–DMA)

Nanoparticle characterization is gaining importance in food technology, biotechnology, medicine, and pharmaceutical industry. An instrument to determine particle electrophoretic mobility (EM) diameters in the single-digit to double-digit nanometer range receiving increased attention is the gas-phase electrophoretic mobility molecular analyzer (GEMMA) separating electrophoretically single charged analytes in the gas-phase at ambient pressure. A fused-silica capillary is used for analyte transfer to the gas-phase by means of a nano electrospray (ES) unit. The potential of this capillary to separate analytes electrophoretically in the liquid phase due to different mobilities is, at measurement conditions recommended by the manufacturer, eliminated due to elevated pressure applied for sample introduction. Measurements are carried out upon constant feeding of analytes to the system. Under these conditions, aggregate formation is observed for samples including high amounts of non-volatile components or complex samples. This makes the EM determination of individual species sometimes difficult, if not impossible. With the current study we demonstrate that liquid phase electrophoretic separation of proteins (as exemplary analytes) occurs in the capillary (capillary zone electrophoresis, CE) of the nano ES unit of the GEMMA. This finding was consecutively applied for on-line desalting allowing EM diameter determination of analytes despite a high salt concentration within samples. The present study is to our knowledge the first report on the use of the GEMMA to determine EM diameters of analytes solubilized in the ES incompatible electrolyte solutions by the intended use of electrophoresis (in the liquid phase) during sample delivery. Results demonstrate the proof of concept of such an approach and additionally illustrate the high potential of a future on-line coupling of a capillary electrophoresis to a GEMMA instrument.     

Excitation of theΔ (1232)-resonance in proton-nucleus collisions

The excitation of theΔ resonance is observed in proton collisions on C, Nb and Pb targets at 0.8 and 1.6 GeV incident energies. The mass E₀ and widthΓ of the resonance are determined from the invariant mass spectra of correlated (p, π^±)-pairs in the final state of the collision: The mass E₀ is smaller than that of the free resonance, however by comparing to intra-nuclear cascade calculations, this reduction is traced back to the effects of Fermi motion, NN scattering and pion reabsorption in nuclear matter.     

On the ways of generalization of adsorption kinetic equations for the case of energetically heterogeneous surfaces

In this work, we present three different ways of incorporation of the effects of surface energetic heterogeneity in the Statistical Rate Theory kinetic equation. These ways are critically discussed and finally, we come to the conclusion that the most consistent method is based on the assumption that the adsorbing surface should not be considered as composed from independent subsystems but it should be treated as one physical entity. As an illustration, we show the numerical analysis of the experimental data concerning the adsorption of CO₂ on scandia. The estimated best-fit parameters are physically correct and consistent with the results of calorimetric measurements.     

Pre- and post-scission neutron emission in the reaction180Hf(40Ar,fission) atE lab=216 MeV

Excitation functions for 19 angles from 82° to 173° have been measured in the laboratory energy range 3.6–5.8 MeV using a thick target method. From the measured excitation functions and from data in the literature, parameters for 18 resonances in³²S have been obtained. The found states have been classified according to dynamical symmetries of the U(4) model. The thick-target method has been evaluated and found to be applicable also to experiments with low bombarding energies.     

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.