Isospin symmetry breaking at high spins in the mirror pair Se-67 and As-67

Recent experimental data have revealed large mirror energy differences (MED) between high-spin states in the mirror nuclei Se-67 and As-67, the heaviest pair where MED have been determined so far. The MED are generally attributed to the isospin symmetry breaking caused by the Coulomb force and by the isospin-nonconserving part of the nucleon-nucleon residual interaction. The different contributions of the various terms have been extensively studied in the fp shell. By employing large-scale shell-model calculations, we show that the inclusion of the g(9/2) orbit causes interference between the electromagnetic spin-orbit and the Coulomb monopole radial terms at high spin. The large MED are attributed to the aligned proton pair excitations from the p(3/2) and f(5/2) orbits to the g(9/2) orbit. The relation of the MED to deformation is discussed.

Inclusive pi(0), eta, and direct photon production at high transverse momentum in p plus p and d plus Au collisions at root s(NN)=200 GeV

We report a measurement of high-p(T) inclusive pi(0), eta, and direct photon production in p + p and d + Au collisions at root s(NN) = 200 GeV at midrapidity (0 < eta < 1). Photons from the decay pi(0) -> gamma gamma were detected in the barrel electromagnetic calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The eta -> gamma gamma decay was also observed and constituted the first eta measurement by STAR. The first direct photon cross-section measurement by STAR is also presented; the signal was extracted statistically by subtracting the pi(0), eta, and omega(782) decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading-order perturbative QCD calculations.

Spectra of identified high-p(T) pi(+/-) and p((p)over-bar ) in Cu + Cu collisions at root s(NN)=200 GeV

We report new results on identified (anti) proton and charged pion spectra at large transverse momenta (3 < p(T) < 10 GeV/c) from Cu + Cu collisions at root s(NN) = 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). This study explores the system size dependence of two novel features observed at RHIC with heavy ions: the hadron suppression at high-p(T) and the anomalous baryon to meson enhancement at intermediate transverse momenta. Both phenomena could be attributed to the creation of a new form of QCD matter. The results presented here bridge the system size gap between the available pp and Au + Au data, and allow for a detailed exploration of the onset of the novel features. Comparative analysis of all available 200 GeV data indicates that the system size is a major factor determining both the magnitude of the hadron spectra suppression at large transverse momenta and the relative baryon to meson enhancement.

Color center formation in silica glass induced by high energy Fe and Xe ions

Silica glass samples were implanted with 1.157 GeV Fe-56 and 1.755 GeV Xe-136 ions to fluences range from 1 x 10(11) to 3.8 x 10(12) ions/cm(2). Virgin and irradiated samples were investigated by ultraviolet (UV) absorption from 3 to 6.4 eV and photoluminescence (PL) spectroscopy. The UV absorption investigation reveals the presence of various color centers (E' center, non-bridging oxygen hole center (NBOHC) and ODC(II)) appearing in the irradiated samples. It is found that the concentration of all color centers increase with the increase of fluence and tend to saturation at high fluence. Furthermore the concentration of E' center and that of NBOHC is approximately equal and both scale better with the energy deposition through processes of electronic stopping, indicating that E' center and NBOHC are mainly produced simultaneously from the scission of strained Si-O-Si bond by electronic excitation effects in heavy ion irradiated silica glass. The PL measurement shows three emissions peaked at about 4.28 eV (alpha band), 3.2 eV (beta band) and 2.67 eV (gamma band) when excited at 5 eV. The intensities of alpha and gamma bands increase with the increase of fluence and tend to saturation at high fluence. The intensity of beta band is at its maximum in virgin silica glass and it is reduced on increasing the ions fluence. It is further confirmed that nuclear energy loss processes determine the production of alpha and gamma bands and electronic energy loss processes determine the bleaching of beta band in heavy ion irradiated silica glass. (c) 2009 Elsevier B.V. All rights reserved.

A high performance Time-of-Flight detector applied to isochronous mass measurement at CSRe

A high performance Time-of-Flight detector has been designed and constructed for isochronous mass spectrometry at the experimental Cooler Storage Ring (CSRe) The detector has been successfully used in an experiment to measure the masses of the N approximate to Z approximate to 33 nuclides near the proton drip-line Of particular interest is the mass of As-65 A maximum detection efficiency of 70% and a time resolution of 118 +/- 8 Ps (FWHM) have been achieved in the experiment The dependence of detection efficiency and signal average pulse height (APH) on atomic number Z has been studied The potential of APH for Z identification has been discussed (C) 2010 Elsevier B V All rights reserved

Two-quasiparticle K-isomeric states in strongly deformed neutron-rich Nd and Sm isotopes: a projected shell-model analysis

Motivated by recent spectroscopy data from fission experiments, we apply the projected shell model to study systematically the structure of strongly deformed, neutron-rich, even-even Nd and Sm isotopes with neutron number from 94 to 100. We perform calculations for rotational bands up to spin I = 20 and analyze the band structure of low-lying states with quasiparticle excitations, with emphasis given to rotational bands based on various negative-parity two-quasiparticle (2-qp) isomers. Experimentally known isomers in these isotopes are described well. The calculations further predict proton 2-qp bands based on a 5(-) and a 7(-) isomer and neutron 2-qp bands based on a 4(-) and an 8(-) isomer. The properties for the yrast line are discussed, and quantities to test the predictions are suggested for future experiment.

A New High-Spin Level Scheme of I-128

High-spin states in the odd-odd nucleus I-128 are investigated via the Sn-124(Li-7,3n)I-128 reaction at 28 and 32 MeV beam energies. A new level scheme of I-128 is established up to high-spin states at I-pi = 16, including 48 levels and 72 gamma transitions. The present level scheme is largely different from the one in a recent publication due to identification of several doublet and triplet gamma transitions and their proper placements in the level scheme. The high-spin level structure exhibits no obvious collective properties and is possibly associated with two and multi-quasiparticle configurations.

Drift distance survey in direct plasma injection scheme for high current beam production

In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C6+ beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance.

Determination and identification of isoflavonoids in Radix astragali by matrix solid-phase dispersion extraction and high-performance liquid chromatography with photodiode array and mass spectrometric detection

The isoflavonoids in Radix astragali were determined and identified by HPLC-photodiode array detection-MS after extraction employing matrix solid-phase dispersion (MSPD). As a new sample preparation method for R. astragali, the MSPD procedure was optimized, validated and compared with conventional methods including ultrasonic and Soxhlet extraction. The amounts of two major components in this herb, formononetin (6) and ononin (2), were determined based on their authentic standards. Four major isoflavonoids, formononetin (6), ononin (2), calycosin (5) and its glycoside (1), and three minor isoflavonoids, (6aR,11aR)-3-hydroxy-9, 10-dimethoxypterocarpan (7), its glycoside (3), and (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavone-7-O-beta-D-glycoside (4), were identified based on their characteristic two-band UV spectra and [M + H](+), [aglycone + H](+) and [A1 + H](+) ions, etc. The combined MSPD and HPLC-DAD-MS method was suitable for quantitative and qualitative determination of the isoflavonoids in R. astragali. (C) 2003 Elsevier B.V. All rights reserved.

Bulk ultrafine binderless (W0.4Al0.6)C prepared by high pressure sintering

Pure (W0.4Al0.6)C powder of about 1 mu m in diameter was sintered by the high pressure sintering (HPS) process without the addition of any binder phase. The microstructure, Vickers micro hardness and density versus the sintering time and temperature are well described. The most suitable sintering condition under pressure of 4.5 GPa is 1873 K for 8 min. Under this sintering condition, the hardness can reach 2295 kg mm(-2) and the relative density can reach 98.6%.

La-2(Zr0.7Ce0.3)(2)O-7 - A new oxide ceramic material with high sintering-resistance

Oxide ceramics with high sintering-resistance above 1473 K have very important applications in thermal barrier coatings (TBCs), catalytic combustion and high-temperature structural materials. Lanthanum zirconate (La2Zr2O7, LZ) is an attractive TBC material which has higher sintering-resistance than yttria stabilized zirconia (YSZ), and this property could be further improved by the proper addition of ceria.

Synthesis and property of a novel sulfonated poly(ether ether ketone) with high selectivity for direct methanol fuel cell applications

Bisphenol monomer 4-carboxylphenyl hydroquinone (4C-PH) containing carboxyl groups was synthesized by diazotization reaction of p-aminobenzoic acid and 1,4-benzoquinone and subsequent reductive reaction. Copolymerization of bisphenol A, 4C-PH, sodium 5,5'-carbonylbis(2-fluorobenzene-sulfonate) and 4,4'-difluorobenzophenone at various molar ratios through aromatic nucleophilic substitution reaction resulted in a new sulfonated poly(ether ether ketone) containing pendant carboxyl groups (C-SPEEK). The structures of the monomer 4C-PH and copolymers were confirmed by FT-IR and H-1 NMR. Flexible and transparent membranes with sulfonic and carboxylic acid groups as the proton conducting sites were prepared. The dependence of ion-exchange capacity (IEC), water uptake, proton conductivity and methanol permeability on the degree of sulfonation has been studied.

Two-Step Spin-Transition Iron(III) Compound with a Wide [High Spin-Low Spin] Plateau

A new iron(III) coordination compound exhibiting a two-step spin-transition behavior with a remarkably wide [HS-LS] plateau of about 45 K has been synthesized from a hydrazino Schiff-base ligand with an N,N,O donor set, namely 2-methoxy-6-(pyridine-2-ylhydrazonomethyl) phenol (Hmph). The single-crystal X-ray structure of the coordination compound {[Fe(mph)(2)](ClO4)(MeOH)(0.5)(H2O)(0.5)}(2) (1) determined at 150 K reveals the presence of two slightly different iron(III) centers in pseudo-octahedral environments generated by two deprotonated tridentate mph ligands. The presence of hydrogen bonding interactions, instigated by the well-designed ligand, may justify the occurrence of the abrupt transitions. 1 has been characterized by temperature-dependent magnetic susceptibility measurements, EPR spectroscopy, differential scanning calorimetry, and Fe-51 Mossbauer spectroscopy, which all confirm the occurrence of a two-step transition. In addition, the iron(III) species in the high-spin state has been trapped and characterized by rapid cooling EPR studies.

Microstructures, mechanical properties and corrosion behavior of high-pressure die-cast Mg-4Al-0.4Mn-xPr (x=1, 2, 4, 6) alloys

Mg-4Al-0.4Mn-xPr (x = 1, 2, 4 and 6 wt.%) magnesium alloys were prepared successfully by the high-pressure die-casting technique. The microstructures, mechanical properties, corrosion behavior as well as strengthening mechanism were investigated. The die-cast alloys were mainly composed of small equiaxed dendrites and the matrix. The fine rigid skin region was related to the high cooling rate and the aggregation of alloying elements, such as Pr. With the Pr content increasing, the alpha-Mg grain sizes were reduced gradually and the amounts of the Al2Pr phase and All, Pr-3 phase which mainly concentrated along the grain boundaries were increased and the relative volume ratio of above two phases was changed. Considering the performance-price ratio, the Pr content added around 4 wt.% was suitable to obtain the optimal mechanical properties which can keep well until 200 degrees C as well as good corrosion resistance. The outstanding mechanical properties were mainly attributed to the rigid casting surface layer, grain refinement, grain boundary strengthening obtained by an amount of precipitates as well as solid solution strengthening.

Microstructure, tensile properties, and creep behavior of high-pressure die-cast Mg-4Al-4RE-0.4Mn (RE = La, Ce) alloys

High-pressure die-cast (HPDC) Mg-4Al-4RE-0.4Mn (RE = La, Ce) magnesium alloys were prepared and their microstructures, tensile properties, and creep behavior have been investigated in detail. The results show that two binary Al-Ce phases, Al11Ce3 and Al2Ce, are formed mainly along grain boundaries in Mg-4Al-4Ce-0.4Mn alloy, while the phase composition of Mg-4Al-4La-0.4Mn alloy contains only alpha-Mg and Al11La3. The Al11La3 phase comprises large coverage of the grain boundary region and complicated morphologies. Compared with Al11Ce3 phase, the higher volume fraction and better thermal stability of Al11La3 have resulted in better-fortified grain boundaries of the Mg-4Al-4La-0.4Mn alloy. Thus higher tensile strength and creep resistance could be obtained in Mg-4Al-4La-0.4Mn alloy in comparison with that of Mg-4Al-4Ce-0.4Mn. Results of the theoretical calculation that the stability of Al11La3 is the highest among four Al-RE intermetallic compounds supports the experimental results further.