C-13 NMR Investigation of Cellobiose in the Presence and Absence of β-Glucosidase

T1(C-13) NMR measurements of cellobiose in aqueous solutions at pH=5 in the presence and absence of enzyme β-glucosidase detected at T=276°K a fast interaction between cellobiose and the enzyme at C1′α level of the disaccharide molecule. T1(C-13) measurements of equal solutions of cellobiose in the presence and absence of EDTA at the same temperatures suggest also a competitive interaction of cellobiose, at C1′α level, with EDTA complexed with a metal ion. T1 data justify a nearly spherical shape of cellobiose in solution.     

Dynamical Calculation of Θ+ Mass and Decay width in the Quark Model

In this paper we study the mass splitting and the decay width of pentaquark (Θ⁺) at the ground states in the framework of flux tube, quark delocalization and color screening model. We consider the pentaquark as diquark-triquark configuration and obtained closer values of mass splitting and the decay width of Θ⁺ to the experimental data.     

Angular Distribution of Production Planes in J/ψ→■ Decay

A new observable, the angle between ■ decay planes, is proposed to test the theoretical predictions on the spin correlation. With 10 billion J/ψ events collected with the BES Ⅲ detector at the BEPCⅡ e~+e~- collider, the distribution of the angle could be measured to verify whether or not a correlation exists.     

Study of proton resonances in 18Ne via resonant elastic scattering of 17F + p and its astrophysical implication in the stellar reaction of 14O(α, p)17F

The stellar ¹⁴O (α, p) ¹⁷F reaction is thought to be one of the most important breakout reactions from the Hot CNO cycles into the rp-process in Type I X-ray bursters. In the present work, the properties of proton resonances in ¹⁸Ne have been investigated efficiently by utilizing a technique of proton resonant elastic scattering with a ¹⁷F radioactive-ion (RI) beam and a thick proton target. A 4.22 MeV/nucleon ¹⁷F RI beam, which was produced via a projectile-fragmentation reaction and experiencing a series of energy degradation, was separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL) and bombarded a (CH₂)_n target. Energy spectra of the recoiled protons were measured by two sets of ΔE-E silicon telescope at center-of-mass scattering angles of θ _c.m. ≈ 175° ± 5°, θ _c.m. ≈ 152° ± 8°, respectively. Several proton resonances in ¹⁸Ne were observed, and their resonant parameters have been determined by an R-matrix analysis of the differential cross-sections. A doublet structure around 7.10 MeV has been identified and thought to be one state at 7.05 MeV (2⁺) and another one at 7.12 MeV (4⁺). The presently calculated total reaction rates of ¹⁴O (α, p) ¹⁷F are, at least, a factor of 1.2 ～ 1.9 larger than the previous ones in a temperature region of 1.7 ～ 3.0 GK mainly owing to the contribution from the 7.05 MeV (2⁺) state. This result implies that this breakout reaction may play a more important role than previously expected.     

Properties of the β-Delayed Proton Decay of 147Er

The β-delayed proton decay of 147Er is studied experimentally using the 58 Ni＋92Mo reaction at a beam energy of 383 MeV. Based on a He-jet apparatus coupled with a tape transport system, the β-delayed proton radioactivities both from the vδl/2 ground state and the vh11/2 isomer in 147 Er are identified by proton-7 coincidence measurements. By analyzing the time distribution of the 4＋ → 2＋-γ transition in the grand-daughter nucleus 146Dy, a half-life of 1.6 ± 0.2s is determined for the Vh11/2 isomer in 147 Er. The half-life for the ground state of 147Er is estimated to be 3.2±1.2 s.     

Dynamic Ionization and Auger Transitions in the Quasi-Molecule during Ne+–Ne Collisions

Journal of Experimental and Theoretical Physics - The exponential component of the electron spectrum during Ne–Ne collisions is shown to be associated with the electron transitions from the...     

Investigation of the 2νEC/EC Decay of 106Cd

Search for the β⁺β⁺, β⁺ EC, and EC/EC modes of the ¹⁰⁶Cd decay was carried out with the TGV-2 (Telescope Germanium Vertical) low-background multidetector spectrometer installed at the Modane underground laboratory (4800 m w.e.). The measured foil samples ～50 μm thick and 52 mm in diameter were placed between the entrance windows of the neighboring detectors inside the cryostat. The total measurement time for 10 g of ¹⁰⁶Cd enriched to 75% was 8687 h. New limits (at the 90% confidence level, CL) were obtained for the ¹⁰⁶Cd half-lives against various branches of the decay to the ground state 0⁺ and excited states 2⁺ of the ¹⁰⁶Pd daughter nucleus. They are T _1/2(2νβ⁺β⁺) ≥ 6.0 × 10¹⁹ y, and T _1/2(2νβ⁺ EC) ≥ 5.9 × 10¹⁹ y, and T _1/2(2νEC/EC) ≥ 3.0 × 10²⁰ y for the transitions to the 0⁺ ground state of ¹⁰⁶Pd; T _1/2(2νβ⁺β⁺) ≥ 5.7 × 10¹⁹ y, T _1/2(2νβ⁺ EC) ≥ 5.9 × 10¹⁹ y, and T _1/2(2νEC/EC) ≥ 4.2 × 10¹⁹ y for the transitions to the 2⁺, 512-keV excited state of ¹⁰⁶Pd; and T _1/2(2νEC/EC) ≥ 3.1 × 10¹⁹ y for the transition to the 0 ₁ ⁺ , 1334-keV excited state of ¹⁰⁶Pd.     

Theoretical Investigation of the Exotic Structure of the Mirror Nuclei ^17Ne and ^17N

The exotic structures of the ground state of the mirror nuclei ^17Ne and ^17N are investigated by means of the asymptotic normalization coefficient （ANC） method to explore the role of the Coulomb interaction, The probebilities of a valence nucleon outside the binding-potential are P = 56.69±2.98/7.46% for ^17Ne and P = 45.51±2.32/5.81% for ^17N. The rms radii are （r^2）^1/2 = 5.06±0.11/0.30 fm and （r^2）^1/2=4.24±0.06/0.16 fm, respectively. The results obtained are nearly independent of the potential parameters. According to the halo occurrence conditions, it is suggested that ^17Ne is a two-proton halo and ^17N is a two-neutron skin. Moreover, two effects of the Coulomb interact-ion on the exotic structure are analysed. From the present results, the exotic structure of the nucleus in the proton-rich side is more obvious than that of its mirror nucleus because of the Coulomb interaction.     

Decay of Z′ in W+W− and Higgs modes

We show that Z′ → WW and into Higgs mode are valuable probes of the symmetry breaking mechanism in gauge theories. Results are derived for a decay of an arbitrary Z′ from string inspired E₆ theory.     

Investigation of the parametric excitation and relaxation of phonons in antiferromagnetic α-Fe2O3

Parametric excitation of magnetoelastic waves was investigated in the easy-plane antiferromagnet α-Fe₂O₃ by parallel and perpendicular microwave pumping over a wide range of frequencies, magnetic fields, and temperatures, and the parametric resonance thresholds were measured. The frequencies of the natural magnetoelastic vibrations of the sample were investigated as a function of the magnetic field and temperature. The results of the measurements were used to calculate the parameters of the magnetoelastic wave spectrum and the rate of relaxation of the excited quasi-phonons. Possible mechanisms for quasi-phonon damping were analyzed.     

Angular Momentum in the Formation of Disk Galaxies

Within the current framework of disk galaxy formation, we discuss the resulted surface-density profiles according to the theoretical angular momentum distributions (AMDs) presented by Bullock et al. [Astrophys. J.555 (2001) 240(B01)] for the ACDM cosmology in both spherical and cylindric coordinates. It is found that the derived surface density distribution of a disk in the outer region is in general similar to an exponential disk for both the theoretical AMDs. In the central region, the results from both the theoretical AMDs are inconsistent with observations whatever the disk bar-instability is taken into account or not. The cylindric form of the theoretical AMD leads to the bar-instability more easily for a give galaxy than that for spherical AMD, which could result in a more massive bulge. After comparing the model predictions with our Milky Way galaxy, we find that the theoretical AMDs predict larger mass fractions of baryons with low angular momentum than the observed ones, which would lead to the disk sizes to be smaller. Two possible processes which could solve the angular momentum problem are discussed.     

Investigation on the deformation of Ne and Mg isotope chains within relativistic mean-field model

Ne and Mg isotope chains are investigated based on constrained calculations in the framework of a deformed relativistic mean-field （RMF） model with the NL075 parameter set. The calculated quadrupole deformation and binding energy are compared with other theoretical results as well as the available experimental data. It shows that the calculated deformations of Ne and Mg with the NL075 are more accurate than those obtained with the NL-SH. It is predicted that ^19,29,32Ne and ^20,31Mg maybe have a triaxial deformation and ^25-28Ne and ^27-30Mg exhibit a shape coexistence probably. The closure effect of neutron number N=8 for ^20Mg is predicted to be very weak.     

Analysis of the bands of the B2Σ+-X2Σ+ transition in 12C16O+ and 13C16O+

The First Negative bands of ¹²C¹⁶O⁺ and ¹³C¹⁶O⁺, in the spectral region 40 000–46 000 cm⁻¹, have been photographed at a resolution sufficient to resolve the spin-doubled components. These data for ¹²C¹⁶O⁺, along with previously reported data of the same transitions, as well as microwave transitions of ¹²C¹⁶O⁺ in the ground state, have been explicitly included in a least-squares fit to determine the most precise set of molecular constants to date for the B²Σ⁺ and X²Σ⁺ states of ¹²C¹⁶O⁺. Furthermore, we report a rotational analysis of the First Negative bands of ¹³C¹⁶O⁺ for the first time. Several molecular constants characterizing ¹³C¹⁶O⁺ in the B²Σ⁺ and the X²Σ⁺ states, including spin-doubling parameters, have been determined.     

Density Dependence of the Mass and Decay Constant of Pion in Nuclear Matter in the Dyson-Schwinger Equation Approach of QCD

With the Dyson-Schwinger equation formalism at finite chemical potential, we study the density dependence of the mass and decay constant of pion in nuclear matter. The calculated results indicate that both the mass and the decay constant remain almost constant at small chemical potential. As the chemical potential gets quite large, the decay constant increases and the mass decreases with the increasing of the chemical potential, and both of them vanish suddenly as a critical value is reached.     

Role of Activator and Vacancy Centers in the Decay of the Gamma Scintillators of CsI–Na Crystals

The influence of the concentration of an activator (C _NaI) and of plastic deformation on a change in the contribution of a slow component to the decay of the -scintillations of CsI–Na crystals was investigated, as well as the influence of C _NaI on a change in the shape of the luminescence excitation spectrum in the region of absorption of activator centers (AC) and of vacancy-related centers (VRC) and also on a change in the intercenter time of deexcitation of the centers indicated. It is shown that AC and VRC participate in the photoluminescence and -scintillations of CsI–Na crystals. In the -scintillations, AC are responsible for the component ₁ = 370 nsec, whereas the components ₁ = 460 nsec and ₂ 2 sec are associated with VRC. The reduction of ₁ from 770 to 560 nsec with an increase in C _NaI from 2·10^–3 to 3·10^–2 mole% and from 570 to 470 nsec after plastic deformation of the crystals ( = 5%) along the 111 axis is caused by a decrease in the number of VRC. The mechanisms underlying the -scintillations of the CaI–Na crystals containing AC and VRC and also the decrease in the number of VRC are discussed.     

Magnetic Field Effect on β^＋ Decay in the Crusts of Accreting Neutron Stars

Based on shell model of nuclei, the influence of a high magnetic field on β^＋ decay in the crusts of accreting neutron stars is analyzed. The magnetic field effect on 54 Mn is discussed. The results show that a weak magnetic field makes little effect on β^＋ decay but a strong magnetic field （B 〉 10^11 G） improves β^＋ decay rates obviously. The conclusion derived will benefit to develop further research on nuclear astrophysics in the future.     

Investigation of constitutional and thermal defects in the ordered β-phases CoGa and NiGa alloys by Mössbauer spectroscopy

The constitutional and thermal defect formation in the Co_100-xGa_x alloys (42⩽x⩽53) and Ni_100-xGa_x alloys (47⩽x⩽52) was studied by Mössbauer spectroscopy. The formation of both constitutional and thermal defects in the CoGa alloys was observed by the appearance of resolved quadrupole split spectral components. The influence of these defects in the NiGa system was detected only by the broadening of the absorption line. The ⁵⁷Fe probe atoms were found to populate the Nisublattice in these alloys. The highest concentration of thermal defects was found in the equiatomic composition of the NiGa alloys.     

EPR and optical spectroscopy of the Yb3+ cubic center in β-PbF2

Optical spectroscopy and EPR are employed to study a β-PbF₂ crystal doped with Yb³⁺ ions. The presence of only one paramagnetic center, the Yb³⁺ ion with cubic symmetry, is established. Its optical lines are identified, the empirical system of energy levels is constructed, and the phenomenological crystal field potential is determined. The information on the phonon spectrum of the β-PbF₂ crystal is obtained from the electron-vibrational structure of the optical absorption and luminescence spectra.