Toward precision mass measurements of neutron-rich nuclei relevant to rr-process nucleosynthesis

The open question of where, when, and how the heavy elements beyond iron enrich our Universe has triggered a new era in nuclear physics studies.\ Of all the relevant nuclear physics inputs, the mass of very neutron-rich nuclides is a key quantity for revealing the origin of heavy elements beyond iron.\ Although the precise determination of this property is a great challenge, enormous progress has been made in recent decades, and it has contributed significantly to both nuclear structure and astrophysical nucleosynthesis studies.\ In this review, we first survey our present knowledge of the nuclear mass surface, emphasizing the importance of nuclear mass precision in $r$-process calculations.\ We then discuss recent progress in various methods of nuclear mass measurement with a few selected examples.\ For each method, we focus on recent breakthroughs and discuss possible ways of improving the weighing of $r$-process nuclides.Comment: 10 figures, review articles in Frontiers of Physic

Ferromagnetism in magnetically doped III-V semiconductors

The origin of ferromagnetism in semimagnetic III-V materials is discussed. The indirect exchange interaction caused by virtual electron excitations from magnetic impurity level in the bandgap to the valence band can explain ferromagnetism in GaAs(Mn) no matter samples are degenerated or not. Formation of ferromagnetic clusters and percolation picture of phase transition describes well all available experimental data and allows to predict the Mn-composition dependence of transition temperature in wurtzite (Ga,In,Al)N epitaxial layers.Comment: 4 pages with 3 figure

Molecular and crystal structure of 6-methyl-3-methoxy-2, 4,4-triphenyl-3-phenylimino-2,3,4,5-tetrahydro-1, 2,3-diazaphosphorine and 3-anilino-6-methyl-3-oxo-2,4, 4-triphenyl-2,3,4,5-tetrahydro-1,2,3-diazaphosphorine

1. 6-Methyl-3-methoxy-2,4,4-triphenyl-3-phenylimino-2,3,4,5-tetrahydro-1,2,3-diazaphosphorine exists as the monomer in the crystalline state. 2. The crystal and molecule structure of the tetrahydrodiazaphosphorine and its solvate with CH3OH added at the P=N bond was determined. © 1983 Plenum Publishing Corporation

Molecular and crystal structure of a product of the reaction of 5-methyl-2-phenyl-1,2,3-diazaphosphol with diazopropane

X-ray diffraction structural analysis established the structure of 2,2,6-trimethyl-1-oxo-1-hydro-4-phenyl-8-[α-phenylhydrazono]ethyl-4,5-diaza-1,3-diphosphabicyclo[3.3.03,7]oct-5-ene, in which a long conjugation chain is realized through the hydrazone group and the adjacent atoms. © 1984 Plenum Publishing Corporation

Molecular structure of cis-syn-cis isomer of 2,2,6,9-tetramethyl-4,11-diphenyl-4,5,10,11-tetraaza-1,3-diphosphatricyclo[6.3.0.03,7]undeca-5, 9-diene

It has been shown by x-ray structure analysis that the interaction of 2-phenyl-5-methyl-1,2,3-diazophosphole with diazopropane forms, along with the cis-anti-cis isomer, the cissyn-cis isomer of 2,2,6,9-tetramethy1-4,11-dipheny1-4,5,10,11-tetraaza-1,3-diphosphatricyclo-[6.3.0.03,7]undeca-5,9-diene. © 1985 Plenum Publishing Corporation

Synthesis and molecular structure of 2,2,6,9-tetramethyl-4, 11-diphenyl-4,5,10,11-tetraaza-1,3-diphosphatricyclo[6.3.0.03,7] undeca-5,9-diene

1. The reaction of 2-phenyl-5-methyl-1,2,3-diazaphosphole with diazapropane yields the first example of the cycloaddition of a phosphorus diylide at the dicoordinated phosphorus P=C bond. 2. X-ray structural analysis unequivocally indicated the structure of the product of this reaction and gave its molecular geometry. © 1983 Plenum Publishing Corporation

Molecular structure of the reaction product of trimethyl phosphite with 3,4,5-trichloro-2(5H)-furanone

The chlorine atom in the 4 position is replaced by a phosphono group in the reaction of 3,4,5-trichloro-2(5H)-furanone with trimethyl phosphite. The structure of dimethyl 3,5-dichloro-2(5H)-furanon-4-ylphosphonate was determined by x-ray diffraction analysis. © 1988 Plenum Publishing Corporation

Solving Grid Equations Using the Alternating-triangular Method on a Graphics Accelerator

The paper describes a parallel-pipeline implementation of solving grid equations using the modified alternating-triangular iterative method (MATM), obtained by numerically solving the equations of mathematical physics. The greatest computational costs at using this method are on the stages of solving a system of linear algebraic equations (SLAE) with lower triangular and upper non-triangular matrices. An algorithm for solving the SLAE with a lower triangular matrix on a graphics accelerator using NVIDIA CUDA technology is presented. To implement the parallel-pipeline method, a three-dimensional decomposition of the computational domain was used. It is divided into blocks along the y coordinate, the number of which corresponds to the number of GPU streaming multiprocessors involved in the calculations. In turn, the blocks are divided into fragments according to two spatial coordinates — x and z. The presented graph model describes the relationship between adjacent fragments of the computational grid and the pipeline calculation process. Based on the results of computational experiments, a regression model was obtained that describes the dependence of the time for calculation one MATM step on the GPU, the acceleration and efficiency for SLAE solution with a lower triangular matrix by the parallel-pipeline method on the GPU were calculated using the different number of streaming multiprocessors.The paper describes a parallel-pipeline implementation of solving grid equations using the modified alternating-triangular iterative method (MATM), obtained by numerically solving the equations of mathematical physics. The greatest computational costs at using this method are on the stages of solving a system of linear algebraic equations (SLAE) with lower triangular and upper non-triangular matrices. An algorithm for solving the SLAE with a lower triangular matrix on a graphics accelerator using NVIDIA CUDA technology is presented. To implement the parallel-pipeline method, a three-dimensional decomposition of the computational domain was used. It is divided into blocks along the y coordinate, the number of which corresponds to the number of GPU streaming multiprocessors involved in the calculations. In turn, the blocks are divided into fragments according to two spatial coordinates — x and z. The presented graph model describes the relationship between adjacent fragments of the computational grid and the pipeline calculation process. Based on the results of computational experiments, a regression model was obtained that describes the dependence of the time for calculation one MATM step on the GPU, the acceleration and efficiency for SLAE solution with a lower triangular matrix by the parallel-pipeline method on the GPU were calculated using the different number of streaming multiprocessors

Influence of the atomic-wall collision elasticity on the coherent population trapping resonance shape

We studied theoretically a coherent population trapping resonance formation in cylindrical cell without buffer gas irradiated by a narrow laser beam. We take into account non-zero probabilities of elastic ("specular") and inelastic ("sticking") collision between the atom and the cell wall. We have developed a theoretical model based on averaging over the random Ramsey pulse sequences of times that atom spent in and out of the beam. It is shown that the shape of coherent population trapping resonance line depends on the probability of elastic collision.Comment: 18 pages, 5 figure