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Relativistic photoionization cross sections for atomic Mg
No full textThe photoionization cross sections of the ground level (3s(2) S-1(0)) of atomic Mg have been studied theoretically in the energy region between the Mg+(3s) and Mg+(3p) threshold using the fully relativistic R-matrix method. The positions and widths of resonances have also been obtained and compared with a recent experiment (Wehlitz et al 2007 J. Phys. B 40 2385). Excellent agreement is shown between our theoretical calculations and experimental measurements. In the present calculations, five Rydberg series of doubly excited states have been exhibited, i.e. 3pns P-1, 3pnd P-1, 3pns P-3, 3pnd D-3 and 3pnd P-3, where 3pnd P-3 are confirmed as the fifth series in contrast to the previous theoretical results
Two Electron Transfer and Stabilization in Slow O6+ and Rare-Gas Collisions
No full textThe stabilization ratios.. for double-electron transfer, i.e., the cross section ratios of true double capture to total double-electron transfer, are measured in O6++ He, Ne and Ar collisions at 6 keV/u. A high.. value about 68% is obtained for the He target, while for the Ar target, the.. value is only 8%. The high R value for the He target is due to the significant direct population of the (2l, nl') configurations with high n For the Ar target, the (quasi) symmetric configurations (3l, nl') lead to the much lower.. value. Neglecting the core effects, the O6+ ion can be taken as a bare ion C6+ except the occupied 1s shell, and then the measured R values are compared with previous experimental results of C6+ projectile ions at similar impact velocity. It yields good agreement with the Ne and Ar target, while the occupied 1s shell for the O6++ He system results in a higher R value than that in C6++He collisions
Finding a Probe for Extracting Information on the Momentum Dependent-Interaction in Heavy Ion Collisions
No full textThe effect of momentum-dependent interaction on the kinetic energy spectrum of the neutron-proton ratio. <(n/p)(gas)>(b)(E-k) for Zn-64 + Zn-64 is studied. It is found that. <(n/p)(gas)>(b)(E-k) sensitively depends on the momentum-dependent interaction and weakly on the in- medium nucleon- nucleon cross section and symmetry potential. Therefore <(n/p)(gas)>(b)(E-k) is a possible probe for extracting information on the momentum-dependent interaction in heavy ion collisions
Observation of a Possible New Isomer in Ir-175
No full textThe neutron deficient nuclide Ir-175 was produced by irradiation of Nd-146 with 210 MeV Cl-35 via a fusion-evaporation reaction channel. The reaction products were transported to a low-background location using a helium-jet recoil fast-moving tape-transport system for measurement. The experimental devices and data analysis method are introduced. Based on the decay-curve fitting of the beta-delayed gamma ray from Ir-175, realized by the least-square method, a new long-lived isomeric state of Ir-175 is proposed and briefly discussed
Relativistic Continuum Random Phase Approximation and Applications I. Formalism
No full textA fully consistent relativistic continuum random phase approximation (RCRPA) is constructed in terms of the Green's function technique. In this method the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single particle Green's function, which includes also the negative states in the Dirac sea in the nose aapproximation. The theoretical formalism of RCRPA and numerical details are presented. The single particle Green's function is calculated numerically by a proper product of regular and irregular solutions of the Dirac equation. The numerical details and the formalism of RCRPA in the momentum representation are presented
The Compact Pulsed Hadron Source: A Design Perspective
No full textDuring the past. decades, large-scale national neutron sources have been developed in Asia, Europe, and North America. Complementing such efforts, compact hadron beam complexes and neutron sources intended to serve primarily universities and industrial institutes have been proposed, and some have recently been established. Responding to the demand in China for pulsed neutron/proton-beam platforms that are dedicated to fundamental and applied research for users in multiple disciplines from materials characterization to hadron therapy and radiography to accelerator-driven sub-critical reactor systems (ADS) for nuclear waste transmutation, we have initiated the construction of a compact, yet expandable, accelerator complex-the Compact Pulsed Hadron Source (CPHS). It consists of an accelerator front-end (a high-intensity ion source, a 3-MeV radio-frequency quadrupole linac (RFQ), and a 13-MeV drift-tube linac (DTL)), a neutron target station (a beryllium target with solid methane and room-temperature water moderators/reflector), and experimental stations for neutron imaging/radiography, small-angle scattering, and proton irradiation. In the future, the CPHS may also serve as an injector to a ring for proton therapy and radiography or as the front end to an ADS test facility. In this paper, we describe the design of the CPHS technical systems and its intended operation
High-spin states and collective band structures in the odd-odd Pm-140 nucleus
No full textThe high-spin states of Pm-140 have been investigated through the reaction Te-126(F-19, 5n) at a beam energy of 90 MeV. A previous level scheme based on the 8(-) isomer has been updated with spin up to 23 (h) over bar. A total of 22 new levels and 41 new transitions were identified. Six collective bands were observed. Five of them were expanded or re-constructed, and one of them was newly identified. The systematic signature splitting and inversion of the yrast pi h(11/2)circle times vh(11/2) band in Pr and Pm odd-odd isotopes has been discussed. Based on the systematic comparison, two Delta I = 2 bands were proposed as double-decoupled bands; other two bands with strong Delta I = 1 M1 transitions inside the bands were suggested as oblate bands with gamma similar to -60 degrees; another band with large signature splitting has been proposed with oblate-triaxial deformation with gamma similar to -90 degrees. The characteristics for these bands have been discussed
The effect of hyperfine interaction on the lifetime of the 3s3p P-3(2) level of Mg-like ions
No full textOn the basis of previous work, the hyperfine-induced 3s3p P-3(2) -> 3s(2) S-1(0) E1 transition probabilities of Mg-like ions were further calculated using the GRASP2K package based on the multiconfiguration Dirac-Hartree-Fock method. The contribution to the lifetime of the P-3(2) level from the 3s3p P-3(2) -> 3s(2) S-1(0) hyperfine-induced E1, 3s3p P-3(2) -> 3s3p P-3(1) M1, 3s3p P-3(2) -> 3s(2) S-1(0) M2 and 3s3p P-3(2) -> 3s3p P-3(0,1) E2 transition was discussed in detail. It was found that hyperfine interaction has an obvious effect on the lifetime at the beginning of the Mg-like isoelectronic sequence
TRITON-(HE)-H-3 RELATIVE AND DIFFERENTIAL FLOWS AND THE HIGH DENSITY BEHAVIOR OF NUCLEAR SYMMETRY ENERGY
No full textUsing a transport model coupled with a phase-space coalescence after-burner we study the triton-He-3 relative and differential transverse flows in semi-central Sn-132 + Sn-124 reactions at a beam energy of 400 MeV/nucleon. We find that the triton-He-3 pairs carry interesting information about the density dependence of the nuclear symmetry energy. The t-He-3 relative flow can be used as a particularly powerful probe of the high-density behavior of the nuclear symmetry energy
CHARMED BARYON IN A STRING MODEL
No full textCharmed baryon spectroscopy has been studied under a string model. In this model, charmed baryons are composed of a diquark and a charm quark which are connected by a constant tension. In this diquark picture, the quantum numbers J(P) of confirmed baryons have been well assigned. Energies of the first and second orbital excitations have been predicted and compared with the experimental data. Meanwhile, diquark masses have been extracted in the background of charm quark which satisfy a splitting relation based on spin-spin interaction