3,472 research outputs found
Magnetic rotation in Rb-82 and Rb-84
No full textHigh-spin states in Rb-82 and Rb-84 were populated in the reaction B-11 +Ge-76 at beam energies of 45 and 50 MeV. gamma rays were detected with the spectrometer GASP. The level schemes of Rb-82 and Rb-84 were extended up to 6.0 and 7.4 MeV, respectively. Mean lifetimes of five levels in Rb-82 and 11 levels in Rb-84 were determined using the Doppler-shift-attenuation method. Regular magnetic dipole bands including strong M1 and weak E2 transitions observed in both nuclei show the characteristic features of magnetic rotation. These bands have been successfully described in the tilted-axis cranking model on the basis of the four-quasiparticle configuration pi(fp) pi(g(9/2)(2)) nu(g(9/2)). The calculations reproduce the band-like properties as well as absolute B(M1) and B(E2) transition strengths in both nuclei, which supports the concept of magnetic rotation. Excited states in Rb-84 were also interpreted in terms of the shell model using the model space pi(0f(5/2),1p(3/2),1p(1/2),0g(9/2)) nu(1p(1/2),0g(9/2)). The predictions for low-lying states agree in general with the experiment. Moreover, calculated states with the main configuration pi(0f(5/2)(-2)1p(3/2)(-1)0g(9/2)(2)) nu(0g(9/2)(-3)) can be combined into M1 sequences which reproduce roughly the experimental transition strengths. However, these sequences do not show the features of magnetic rotation such as regular level spacings and B(M1) values which decrease with increasing rotational frequency
Mapping and Confirmation of a New Allele at \u3ci\u3eRpp1\u3c/i\u3e from Soybean PI 594538A Conferring RB Lesion–Type Resistance to Soybean Rust
No full textSoybean rust, caused by Phakopsora pachyrhizi (H. Sydow & Sydow), is a destructive soybean [Glycine max (L.) Merr.] disease and identification of new resistance genes is essential for effective rust management. Our research objectives were to map and confirm the location of resistance gene(s) in PI 594538A using a population of 98 F3:4 lines from across between PI 594538A (reddish-brown [RB] lesions) and the susceptible cultivar Loda (tan [TAN] lesions). The lines were inoculated with the P. pachyrhizi isolate ZM01-1 from Zimbabwe. The RB resistance in PI 594538A mapped on linkage group G as a single dominant gene. This gene is likely an allele of Rpp1 or a new closely linked gene because it mapped within 1 cM of Rpp1 and ZM01-1 produced RB lesions on PI 594538A and TAN lesions on PI 200492, the original source of Rpp1. The mapping of the new Rpp1 allele, named Rpp1-b, was confirmed in a second population
Transition cancellations of Rb and Rb atoms in a magnetic field setting new standards
No full textWe have analyzed the magnetic field dependences of intensities of all the optical transitions between magnetic sublevels of hyperfine levels, excited with , and polarized light, for the and lines of Rb and Rb atoms. Depending on the type of transition and the quantum numbers of involved levels, the Hamiltonian matrices are of , , or dimension. As an example, analytical expressions are presented for the case of dimension matrices for line of both isotopes. Eigenvalues and eigenkets are given, and the expression for the transition intensity as a function of has been determined. It is found that some transitions of Rb and Rb get completely canceled for certain, extremely precise, values of . No cancellation occurs for or transitions of line. For matrices with size over , analytical formulas are heavy, and we have performed numerical calculations. All the values cancelling , and transitions of and lines of Rb and Rb are calculated, with an accuracy limited by the precision of the involved physical quantities. We believe our modeling can serve as a tool for determination of standardized values of magnetic field. The experimental implementation feasibility and its possible outcome are addressed. We believe the experimental realization will allow to increase precision of the physical quantities involved, in particular the upper state atomic levels energy
Direct observation of the 2 (3)Pi(u) state of Rb-2 in a pulsed molecular beam: Rotational branch intensity anomalies in the 2 (3)Pi(u)(1(u))-X (1)Sigma(+)(g)(0(g)(+)) bands
No full textResonance enhanced two photon ionization study in a pulsed molecular beam identified spin-forbidden transitions of the 2 (3)Pi(u)(1(u))-X (1)Sigma(g)(+)(0(g)(+)) and 2 (3)Pi(u)(0(u)(+))-X (1)Sigma(g)(+)(0(g)(+)) of Rb-2. Lambda-doubling and interference-induced rotational branch intensity anomalies are observed for 2 (3)Pi(u)(1(u))-X (1)Sigma(g)(+)(0(g)(+)) transitions. The rotational constant for the 2 (3)Pi(u) state was determined to be B-e=0.018 932 5 +/- 0.000 007 4 cm(-1) for Rb-85(2), giving R-e=4.5796 +/- 0.0009 Angstrom. Other molecular parameters for Rb-85(2) are determined as T-e=19 784.254 +/- 0.009 cm(-1), omega(e)=42.200 +/- 0.006 cm(-1), omega(e)x(e)=0.171 +/- 0.001 cm(-1), and omega(e)y(e)=-0.001 06 +/- 0.000 06 cm(-1) for the 2 (3)Pi(u)(0(u)(+)) state and T-e=19 785.74 +/- 0.01 cm(-1), omega(e)=42.297 +/- 0.005 cm(-1), omega(e)x(e)=0.1725 +/- 0.0009 cm(-1), and omega(e)y(e)=-0.000 78 +/- 0.000 04 cm(-1) for 2 (3)Pi(u)(1(u)) state. These R-e, omega(e), and T-e values agree well with ab initio calculated values. The spin-orbit coupling constant A and Lambda-doubling parameters p and q are determined by simultaneous fitting of the rotational structures of both 2 (3)Pi(u)(1(u))-X (1)Sigma(g)(+) and 2 (3)Pi(u)(0(u)(+))-X (1)Sigma(g)(+) transitions. (C) 2000 American Institute of Physics. [S0021-9606(00)01830-4]
Liquid structure of Rb-Hg alloys studied by neutron diffraction
No full textThe structures of liquid Rb–Hg alloys were studied as a function of composition by neutron diffraction. In the intermediate Rb concentration range, the obtained structure factors show a small prepeak, which may be an evidence of the formation of Hg polyanion units in liquids. The Reverse Monte Carlo (RMC) analysis was applied to separate the total radial distribution function into the corresponding partial radial distribution functions. Up to 10 at.% Rb, no obvious changes are found for the first peak position of the partial radial distribution functions of the Hg–Hg pair and that of the Hg–Rb pair. The first peak position between the Hg–Rb pairs increases above 20 at.% Rb. In addition to the first peak, a subpeak between Hg–Hg pairs can be seen in the large distance. At 60 at.% Rb, the nearest neighbor distance between Hg atoms shows the closest value in the concentration range studied. These results indicate that with the progress of charge transfer the solvation structure in the dilute Rb concentration range changes into the structure containing polyanions composed of Hg species
Breakup of quantum liquid filaments
No full textWe investigate how the Rayleigh-Plateau instability of a filament made of a 41 K - 87 Rb self-bound mixture may lead to an array of identical quantum droplets, with typical breaking times which are shorter than the lifetime of the mixture. If the filament is laterally confined, as it happens in a toroidal trap, and atoms of one species are in excess with respect to the optimal equilibrium ratio, the droplets are immersed into a superfluid background made by the excess species which provides global phase coherence to the system, suggesting that the droplet array in the unbalanced system may display supersolid character. This possibility is investigated by computing the nonclassical translational inertia coefficient. The filament may be a reasonable representation of a self-bound mixture subject to toroidal confinement when the bigger circle radius of the torus is much larger than the filament radius
Magnetic rotation in the A=80 region: M1 bands in heavy Rb isotopes
No full textWe have studied the isotopes Rb-82(45), Rb-83(46), and Rb-84(47) to search for magnetic rotation which is predicted in the tilted-axis cranking model for a certain mass region around A = 80. Excited states in these nuclei were populated via the reaction B-11 + Ge-76 with E = 50 MeV at the XTU tandem accelerator of the LNL Legnaro. Based on a gamma-coincidence experiment using the spectrometer GASP we have found magnetic dipole bands in each studied nuclide. The regular M1 bands observed in the odd-odd nuclei Rb-82 and Rb-84 include B(M1)/B(E2) ratios decreasing smoothly with increasing spin in a range of 13(-) less than or equal to J(pi) less than or equal to 16(-). These bands are interpreted in the tilted-axis cranking model on the basis of four-quasiparticle configurations of the type pi(fp) pi g(9/2)(2) nu g(9/2). This is the first evidence of magnetic rotation in the A approximate to 80 region. In contrast, the M1 sequences in the odd-even nucleus Rb-83 are not regular, and the B(M1)/B(E2) ratios show a pronounced staggering
High-spin states and level structure in Rb-84
No full textHigh-spin states in Rb-84 have been studied by using the Zn-70(O-18,p3n)Rb-84 reaction at beam energy of 75 MeV. The gamma-gamma coincidence, excitation function, and ratios for directional correlation of oriented states were determined. A new level scheme was established in which the positive-and negative-parity bands have been extended up to 17(+) and 17(-) with an excitation energy of about 7 MeV. The signature splitting and signature inversion of the positive-parity yrast band were observed. To understand the microscopic origin of the signature inversion in the yrast positive-parity bands of doubly odd Rb nuclei, as an example, we performed calculations using the projected shell model to describe the energy spectra in Rb-84. It can be seen that the main features are reproduced in the calculations. This analysis shows that the signature splitting, especially its inversion, can be reproduced by varying only the. deformation with increasing spin. To research the deformation of Rb-84 carefully, we calculate the total Routhian surfaces of positive-parity yrast states by the cranking shell model formalism. In addition, the results of theoretical calculations about the negative-parity yrast band in Rb-84 with configuration pi(p(3/2), f(5/2)) circle times nu g(9/2) are compared with experimental data, and a band diagram calculated for this band is also shown to extract physics from the numerical results.Physics, NuclearSCI(E)2ARTICLE1null8
The N=Z nuclide with
No full textImproved experimental techniques have permitted the observation of the new nuclide /sup 74/Rb with a half-life of 64.9+or-0.5 ms, which represents the heaviest self-conjugate nuclear detected until now. The absence of a long-lived isomer indicates that the T=0 state of /sup 74 /Rb lies above the T=1 state. An upper limit of 10/sup -3/ relative to /sup 74/Rb can be placed on the yield of the (unobserved) mirror nucleus /sup 73/Rb, and appears likely that the limit of particle stability has been reached. The half-life of /sup 75/Rb is 17.0+or-1.0 s. (19 refs)
Fractional Edge Cover Number of Model RB
No full textModel RB is a random constraint satisfaction problem with a growing domain size, which exhibits exact phase transition phenomena. Many hard instances with planted solutions can be generated via Model RB, to be used as benchmarks for algorithmic competitions and researches. In the past, some structural parameters of constraint hypergraphs are analyzed to show hardness of Model RB, such as hinge width, decycling number, treewidth, and hypertree width. In this paper, one more structural parameter of constraint hypergraphs of Model RB, namely the fractional edge cover number, is analyzed. We show upper and lower bounds on the fractional edge cover number of Model RB. In particular, the fractional edge cover number of Model RB is shown to be asymptotically linear in the number of variables, like hinge width, decycling number, treewidth and hypertree width. These results together provide further evidences on the hardness of Model RB.EICPCI-S(ISTP)[email protected]
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