Experimental evidence for low-spin members of “upper” bands in156Dy

Study of the energy levels of¹⁵⁶Dy through the¹⁵⁹Tb(p, 4n)¹⁵⁶Dy reaction has revealed the existence of six states with excitation energies between 1.8 and 2.8 MeV and spins between 6 and 12. Some of them can tentatively be assigned as low-spin members of “upper” bands which are thought to be responsible for the backbending phenomenon experimentally observed in the ground-state andβ-vibrational bands of this nucleus. Others could be levels of a negative-parity octupole band.     

Level structure of 22Mg: implications for the 21Na(p,gamma)22Mg astrophysical reaction rate and for the 22Mg Mass

The level structure of (22)Mg has been studied with high-sensitivity gamma-ray spectroscopy techniques. A complete level scheme is derived incorporating all subthreshold states and all levels in the energy region relevant for novae burning. The excitation energy of the most important astrophysical resonance is measured with improved accuracy and found to differ from previous values. Combining the present result with a recent resonance energy measurement of this state leads to a derived (22)Mg mass excess of -400.5(13) keV.     

High-spin structure of N\simeq Z nuclei around the A = 72 region

High-spin states have been studied in ⁷²Kr and ⁷²Br using the ⁴⁰Ca + ⁴⁰Ca and ³⁶Ar + ⁴⁰Ca reactions at 164 and 145 MeV, respectively. The properties and configurations of the high-spin bands observed have been interpreted using unpaired cranked Nilsson-Strutinsky (CNS), and for ⁷²Kr, paired cranked relativistic Hartree-Bogoliubov (CRHB) calculations. In ⁷²Kr a new band has been identified that has the properties expected for the doubly aligned S-band configuration. In ⁷²Br the previously known bands have been extended to higher spin. This has lead to a re-interpretation of the configurations.Received: 31 October 2002, Published online: 24 February 2004PACS: 21.10.Re Collective levels - 23.20.Lv transitions and level energies - 27.50. + e      

Entry distribution, fission barrier, and formation mechanism of 254102No

The entry distribution in angular momentum and excitation energy for the formation of 254No has been measured after the 208Pb(48Ca,2n) reaction at 215 and 219 MeV. This nucleus is populated up to spin 22Planck's over 2pi and excitation energy greater, similar6 MeV above the yrast line, with the half-maximum points of the energy distributions at approximately 5 MeV for spins between 12Planck's over 2pi and 22Planck's over 2pi. This suggests that the fission barrier is greater, similar5 MeV and that the shell-correction energy persists to high spin.     

Beta-delayed γ-ray studies of πf7/2 - νpf shell nuclei

We have utilized the selective process of β decay to populate low-energy excited states in the neutron-rich ₂₂Ti, ₂₃V, ₂₄Cr, and ₂₅Mn nuclei. The goal was to systematically track the monopole shift of the νf_5/2 single-particle level with increased occupancy of the πf_7/2 orbital. The β-decay properties of the parent nuclides, along with the low-energy structure of the daughters, are presented and compared with the results of shell model calculations employing the GXPF1 interaction.     

μ-XRF/μ-RS vs. SR μ-XRD for pigment identification in illuminated manuscripts

For the non-destructive identification of pigments and colorants in works of art, in archaeological and in forensic materials, a wide range of analytical techniques can be used. Bearing in mind that every method holds particular limitations, two complementary spectroscopic techniques, namely confocal μ-Raman spectroscopy (μ-RS) and μ-X-ray fluorescence spectroscopy (μ-XRF), were joined in one instrument. The combined μ-XRF and μ-RS device, called PRAXIS unites both complementary techniques in one mobile setup, which allows μ- and in situ analysis. μ-XRF allows one to collect elemental and spatially-resolved information in a non-destructive way on major and minor constituents of a variety of materials. However, the main disadvantages of μ-XRF are the penetration depth of the X-rays and the fact that only elements and not specific molecular combinations of elements can be detected. As a result μ-XRF is often not specific enough to identify the pigments within complex mixtures. Confocal Raman microscopy (μ-RS) can offer a surplus as molecular information can be obtained from single pigment grains. However, in some cases the presence of a strong fluorescence background limits the applicability. In this paper, the concrete analytical possibilities of the combined PRAXIS device are evaluated by comparing the results on an illuminated sheet of parchment with the analytical information supplied by synchrotron radiation μ-X-ray diffraction (SR μ-XRD), a highly specific technique. PACS  33.20.Fb; 61.05.cp; 33.20.Rm; 07.85.Qe; 91.65.An     

Study of 169Hf at high rotational frequency

High-spin properties of the nucleus ¹⁶⁹Hf have been studied through the fusion evaporation reaction ⁹⁶Zr(⁷⁶Ge,3n)¹⁶⁹Hf at a beam energy of 310 MeV. The known rotational bands have been extended considerably and 6 new bands have been established, four of which form coupled bands with pronounced M1 connections. Quasiparticle assignments are suggested for the new band structures, and it appears that coupling to vibrational degrees of freedom plays a role. Both coupled bands involve the excitation of quasiprotons. In the region of highest spin, a large alignment gain is interpreted in terms of a mixed crossing where an h _9/2 and an h _11/2 quasiproton provide the two signatures of the aligning configuration. Received: 23 March 2001 / Accepted: 20 September 2001     

B-site ordered perovskite LaSrMnNbO6: Synthesis, structure and antiferromagnetism

LaSrMnNbO₆ has been synthesized by high temperature solid state reaction under 1% H₂/Ar dynamic flow. The structure is determined by Rietveld refinement of the powder X-ray diffraction data. It crystallizes in the monoclinic space group P2₁/n with the unit cell parameters: a=5.69187(12), b=5.74732(10), c=8.07018(15) Å and β=90.0504(29)°, which were also confirmed by electron diffraction. The Mn²⁺ and Nb⁵⁺ ions, whose valence states are confirmed by X-ray absorption near-edge spectroscopy, are almost completely ordered over the B-site (<1% inversion) of the perovskite structure due to the large differences of both cationic size (0.19 Å) and charge. The octahedral framework displays significant tilting distortion according to Glazer’s tilt system a⁻b⁻c⁺. Upon heating, LaSrMnNbO₆ decomposes at 690 °C under O₂ flow or at 775 °C in air. The magnetic susceptibility data indicate the presence of long-range antiferromagnetic ordering at T_N=8 K; the experimentally observed effective paramagnetic moment, μ_eff=5.76 μ_B for high spin Mn²⁺ (3d⁵, S=5/2) is in good agreement with the calculated value (μ_calcd=5.92 μ_B).     

Convenient synthesis of Cu3(BTC)2 encapsulated Keggin heteropolyacid nanomaterial for application in catalysis

Nanomaterial of Cu(3)(BTC)(2) (BTC = benzene tricarboxylic acid) incorporating Keggin heteropolyacid conveniently prepared at room temperature and recovered by freeze drying outperforms ultrastable Y zeolite in acid catalysed esterification reaction.     

Parameters affecting the separation of intact proteins in gradient-elution reversed-phase chromatography using poly(styrene-co-divinylbenzene) monolithic capillary columns

An experimental study was performed to investigate the effects of column parameters and gradient conditions on the separation of intact proteins using styrene-based monolithic columns. The effect of flow rate on peak width was investigated at constant gradient steepness by normalizing the gradient time for the column hold-up time. When operating the column at a temperature of 60 °C a small C-term effect was observed in a flow rate range of 1–4 μL/min. However, the C-term effect on peak width is not as strong as the decrease in peak width due to increasing flow rate. The peak capacity increased according to the square root of the column length. Decreasing the macropore size of the polymer monolith while maintaining the column length constant, resulted in an increase in peak capacity. A trade-off between peak capacity and total analysis time was made for 50, 100, and 250 mm long monolithic columns and a microparticulate column packed with 5 μm porous silica particles while operating at a flow rate of 2 μL/min. The peak capacity per unit time of the 50 mm long monolithic column with small pore size was superior when the total analysis time is below 120 min, yielding a maximum peak capacity of 380. For more demanding separations the 250 mm long monolith provided the highest peak capacity in the shortest possible time frame.