Coulomb distortion and medium corrections in nucleon-removal reactions

One-nucleon removal reactions at or above the Fermi energy are important tools to explore the single-particle structure of exotic nuclei. Experimental data must be compared with calculations to extract structure information, evaluate correlation effects in nuclei or determine reaction rates for nuclear astrophysics. However, there is insufficient knowledge to calculate accurately the cross sections for these reactions. We evaluate the contributions of the final state interaction (FSI) and of the medium modifications of the nucleon-nucleon interactions and obtain the shapes and magnitudes of momentum distributions. Such effects have been often neglected in the literature. Calculations for reactions at energies 35 - 1000 MeV/nucleon are reported and compared to published data. For consistency, the state-of-the-art eikonal method for stripping and diffraction dissociation is used. We find that the two effects are important and their relative contributions vary with the energy and with the atomic and mass number of the projectile involved. These two often neglected effects modify considerably the one-nucleon removal cross sections. As expected, the effect are largest at lower energies, around 50 MeV/nucleon and on heavy targets.Comment: 12 pages, 10 figures. Accpeted for publication in the Physical Review C. arXiv admin note: text overlap with arXiv:nucl-th/0407026 by other author

Astrophysical S factor for the radiative capture 12N(p,gamma)13O determined from the 14N(12N,13O)13C proton transfer reaction

The cross section of the radiative proton capture reaction on the drip line nucleus 12N was investigated using the Asymptotic Normalization Coefficient (ANC) method. We have used the 14N(12N,13O)13C proton transfer reaction at 12 MeV/nucleon to extract the ANC for 13O -> 12N + p and calculate from it the direct component of the astrophysical S factor of the 12N(p,gamma)13O reaction. The optical potentials used and the DWBA analysis of the proton transfer reaction are discussed. For the entrance channel, the optical potential was inferred from an elastic scattering measurement carried out at the same time with the transfer measurement. From the transfer, we determined the square of the ANC, C^2(13Og.s.) = 2.53 +/- 0.30 fm-1, and hence a value of 0.33(4) keVb was obtained for the direct astrophysical S factor at zero energy. Constructive interference at low energies between the direct and resonant captures leads to an enhancement of Stotal(0) = 0.42(5) keVb. The 12N(p,gamma)13O reaction was investigated in relation to the evolution of hydrogen-rich massive Population III stars, for the role that it may play in the hot pp-chain nuclear burning processes, possibly occurring in such objects.Comment: 15 pages, 10 figures, 3 tables submitted to Phys. Rev.

A 3D Visualization Approach for Process Training in Office Environments

Process participants need to learn how to perform in the context of their business processes. Process training is challenging due to cognitive difficulties in relating process model elements to real world concepts. In this paper we present a 3d virtual world (vw) process training approach for office environments. In this vw, process participants can experience a process in an immersive environment. They interact with vw representations of process elements in changing locations, based on process activities. By means of embodied 3d representation, deep immersion and engagement in this environment, enhancements in long term memory learning and episodic memory usage for knowledge retrieval are expected. Our illustration of an example process model shows the applicability of the approach. We list a number of future directions to extend the use and the benefits

Performance evaluation of novel square-bordered position-sensitive silicon detectors with four-corner readout

We report on a recently developed novel type of large area (62 mm x 62 mm) position sensitive silicon detector with four-corner readout. It consists of a square-shaped ion-implanted resistive anode framed by additional low-resistivity strips with resistances smaller than the anode surface resistance by a factor of 2. The detector position linearity, position resolution, and energy resolution were measured with alpha-particles and heavy ions. In-beam experimental results reveal a position resolution below 1 mm (FWHM) and a very good non-linearity of less than 1% (rms). The energy resolution determined from 228Th alpha source measurements is around 2% (FWHM).Comment: 13 pages, 10 figures, submitted to Nucl. Instr. and Meth.

Fermi surface in BaNi2_2P2_2

We report measurements of the de Haas-van Alphen (dHvA) oscillation and a band structure calculation for the pnictide superconductor BaNi$_2$P$_2$, which is isostructural to BaFe$_2$As$_2$, the mother compound of the iron-pnictide high-$T_c$ superconductor (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$. Six dHvA-frequency branches with frequencies up to $\sim$8 kT were observed, and they are in excellent agreement with results of the band-structure calculation. The determined Fermi surface is large, enclosing about one electron and hole per formula unit, and three-dimensional. This is in contrast to the small two-dimensional Fermi surface expected for the iron-pnictide high-$T_c$ superconductors. The mass enhancement is about two.Comment: To appear in J. Phys. Soc. Jpn., Vol. 78, No.

POWER MANAGEMENT TECHNIQUES FOR A GRID CONNECTED HYBRID SYSTEM WITH COORDINATE CONTROL

This paper presents the methods and strategies of coordinating hybrid system by using their constraints also giving picture about total harmonic distortion values. The system utilizes a photovoltaic system as a primary source and proton exchange membrane fuel cell as auxiliary source. The photovoltaic system is can be operated at maximum power point by using the technique MPPT(maximum power point tracking) and the fuel cell can be operates at its maximum efficiency range. The controller we are using here is fuzzy logic controller with this we can reduce the value of total harmonic distortion when compared to other controllers. Two modes of operation are feeder control mode and unit power control mode. Hence we can achieve the controllable operation, improving system performance with reduced running conditions, enhance system stability and total harmonic distortion can be reduced. The model is designed by using MATLAB software

Measurement of the 20 and 90 keV resonances in the 18O(p,α)15{}^{18}{\rm O}(p,\alpha){}^{15}N reaction via THM

The $^{18}{\rm O}(p,\alpha)^{15}{\rm N}$ reaction is of primary importance in several astrophysical scenarios, including fluorine nucleosynthesis inside AGB stars as well as oxygen and nitrogen isotopic ratios in meteorite grains. Thus the indirect measurement of the low energy region of the $^{18}{\rm O}(p,\alpha)^{15}{\rm N}$ reaction has been performed to reduce the nuclear uncertainty on theoretical predictions. In particular the strength of the 20 and 90 keV resonances have been deduced and the change in the reaction rate evaluated.Comment: 4 pages, 4 figures, submitted to PR

Precise Half-Life Measurement of the Superallowed Beta+ Emitter 26Si

We have measured the half-life of the superallowed 0+ -to- 0+ beta+ emitter 26Si to be 2245.3(7) ms. We used pure sources of 26Si and employed a high-efficiency gas counter, which was sensitive to positrons from both this nuclide and its daughter 26mAl. The data were analyzed as a linked parent-daughter decay. To contribute meaningfully to any test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the ft value of a superallowed transition must be determined to a precision of 0.1% or better. With a precision of 0.03% the present result is more than sufficient to be compatable with that requirement. Only the branching ratio now remains to be measured precisely before a +/-0.1% ft value can be obtained for the superallowed transition from 26Si