International Nuclear Information System (INIS)

The "7Be(#alpha#,#gamma#)"1"1C and "7Li(#alpha#,#gamma#)"1"1B reactions are investigated in the three-cluster Generator Coordinate Method. The microscopic wave functions are described from #alpha# and "3He ("3H) clusters, with two coupling modes: #alpha#+"7Be ("7Li) and "3He ("3H)+"8Be. Different internal states of "7Be ("7Li) and "8Be are taken into account. The model is tested on "1"1C and "1"1B spectroscopic properties, which agree fairly well with experiment. We suggest that, in both nuclei, the (3)/(2)"- and (5)/(2)"- states located close to the #alpha#+"7Be ("7Li) threshold, are intruder states. The "7Be(#alpha#,#gamma#)"1"1C and "7Li(#alpha#,#gamma#)"1"1B reaction rates are calculated for temperatures up to 10"9 K. A strong enhancement is found with respect to the reaction rates currently used in astrophysical ...

Energy Technology Data Exchange (ETDEWEB)

Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds were studied by electron and proton bombardments. L{sub {gamma}1} X-rays which involve transition of 4d electrons of the valence shell were found to be sensitive to the chemical environment. The L{sub {gamma}1}/L{sub {beta}1} X-ray intensity ratio increased with an increase of the 4d electron occupation of niobium or molybdenum in niobium or molybdenum compounds, showing that the chemical effects can be ascribed to the 4d electron behavior of the metallic atom in its compounds. (orig.).

International Nuclear Information System (INIS)

Low-lying nuclear energy levels in "1"1"0In and "1"1"2In were determined from de-excitation #gamma#-rays produced with "1"0"7Ag(#alpha#,n#gamma#)-"1"1"0In, "1"0"8Pd("6Li,4n#gamma#)"1"1"0In, "1"0"9Ag(#alpha#,n#gamma#)"1"1"2In and "1"1"0Pd("6Li,4n#gamma#)"1"1"2In reactions. In addition, the "1"1"4In energy level structure was investigated with the "1"1"0Pd("7Li,3n#gamma#)"1"1"4In reaction. Properties of de-excitation #gamma#-rays were determined from #gamma#-#gamma# coincidence, excitation, and angular distribution measurements conducted with Ge(Li) and Ge(intr.) #gamma#-ray detectors. A sequence of intraconnected levels in each of "1"1"0,"1"1"2,"1"1"4In were assigned to the (#pi#g"-"1/sub 9/2/, #nu#h/sub 11/2/) configuration. For the "1"1"0,"1"1"2,"1"1"4In energy level schemes a ...

International Nuclear Information System (INIS)

The results of photoneutron spectra measurements for the reaction (#gamma#,n) on the Sr-88 nuclei near threshold are presented. The parameters of resonance levels, as well as radiative S_#gamma#"("1") and neutron S_n"("1") strength functions for transitions on the first excited level of Sr-87 were obtained. 2 refs.; 1 fig.; 1 tab.

Science.gov (United States)

Some authors have concluded that spiral structures and shocks do not develop if an adiabatic index gamma > 1.16 is adopted in accretion disc modelling, whilst others have claimed that they obtained well defined spirals and shocks adopting a gamma = 1.2 and a M_2/M_1 = 1 stellar mass ratio. In our opinion, it should be possible to develop spiral structures for low compressibility gas accretion discs if the primary component is a black hole. We considered a primary black hole of 8 solar mass and a small secondary component of 0.5 solar mass to favour spiral structures formations and possible spiral shocks via gas compression due to a strong gravitational attraction. We performed two 3D SPH simulations and two 2D SPH simulations and characterized a low compressibility model and a high compressibility model for each couple of simulations. 2D models reveal spiral structures existence. Moreover, spiral ...

CERN Document Server

This paper focuses on the analysis of average Gaussian error probabilities in certain fading channels, i.e. we are interested in E[Q((p {\\gamma})^(1/2))] where Q(.) is the Gaussian Q-function, p is a positive real number and {\\gamma} is a nonnegative random variable. We present a unified analysis of the average Gaussian error probability, derive a compact expression in terms of the Lauricella FD^(n) function that is applicable to a broad class of fading channels, and discuss the relation of this expression and expressions of this type recently appeared in literature. As an intermediate step in our derivations, we also obtain a compact expression for the outage probability of the same class of fading channels. Finally, we show how this unified analysis allows us to obtain novel performance analytical results.

International Nuclear Information System (INIS)

The problem in perturbation theory in general relativity is finding a natural gauge which simplifies the equations considerably. We solved the first and second order perturbation equations in the ''Lorentz gauge'' using the two-timing method. The equations were deduced from the equations of Einstein in the presence of a matter energy-momentum tensor of a perfect fluid with equation of state p = (#gamma#-1) rho. It is found that the 0--0 component of the first order equations together with the gauge conditions are consistent with the Bianchi type V model, without axial symmetry. It represents a ''ground state'' situation of the Bianchi type IX model (Mixmaster model.) The second order equations, describing the reaction back of the gravitational waves on the slowly varying background, give rise to rotation and will disturb the isotropization mechanism. The numerical solutions show all the features which are expected to appear. Moreover, it is ...

Science.gov (United States)

The results of a computational scheme of Rose (a method for calculating solutions of parabolic equations with free boundary, Math. Comp., 14: 249-256(1960)) are compared with the known analytic solution of a single-phase Stefan problem with constant boundary temperature. Rose's scheme was implemented in FORTRAN on a DEC PDP-10. Computations were performed for Stefan numbers St = 0.01, 0.1, 1, 10, and 100. Three relative mesh sizes (..gamma.. = DT/(DX)/sup 2/ = 1/2, 1/6, and 1/25) were used. For each St, the relative mesh size had very little effect on accuracy. However, taking ..gamma.. = 1/25 resulted in dramatically increased computing time. The relative errors of temperature were large near the phase change front. 11 figures, 5 tables.

Energy Technology Data Exchange (ETDEWEB)

In this paper, the wavefunction of the universe with a tunneling boundary condition is considered in the context of the Brans-Dicke-type scalar-tensor theory with matter. The matter may be interpreted as a D-particle (or D0-brane) in string theory when the Brans-Dicke parameter {omega} is -1. We study two simple examples. The first example, the {gamma}=0 (matter) case, has a scale factor duality even if the low energy string action is coupled to matter. The universe undergoes quantum transition from super-inflationary (pre-big-bang) to deflationary (post-big-bang) phase. We calculate the transition rate by solving the Wheeler-DeWitt equation and find that it is non-vanishing. The two phases are disconnected classically. The second example is the {gamma}=1/3(radiation) case. With the help of earlier work this matter can be identified with a D0-brane in string theory. In this case, due to the absence of the scale factor duality and the ...

CERN Document Server

We explore the relationship between the hard X-ray photon index $\\Gamma$ and the Eddington ratio (\\xi=L_{X}(0.5-25 keV)/L_{Edd}) in six XRBs. We find that different XRBs follow different anti-correlations between $\\Gamma$ and $\\xi$ when $\\xi$ is less than a critical value, while they follow the same positive correlation when $\\xi$ is larger than the critical value. This anti-correlation and positive correlation are also found in LLAGNs and QSOs respectively, and the anti-correlation and positive correlation of different XRBs roughly converge to the same point ($\\log \\xi=-2.1, \\Gamma=1.5$), which may correspond to the accretion mode transition, since that the anti-correlation and positive correlation are consistent with the prediction of ADAFs and standard disk/corona system respectively. The traditional low/hard state are divided into two parts by the cross point $\\log \\xi\\sim-2.1$, i.e., faint-hard state in the anti-correlation ...

CERN Document Server

We report the observation of two narrow structures at 10610MeV/c^2 and 10650MeV/c^2 in the pi^{\\pm}Upsilon(nS) (n=1,2,3) and pi^{\\pm}h_b(mP) (m=1,2) mass spectra that are produced in association with a single charged pion in Upsilon(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M_1=10608.4\\pm2.0MeV/c^2, Gamma_1=15.6\\pm2.5MeV and M_2=10653.2\\pm1.5MeV/c^2, Gamma_2=14.4\\pm3.2MeV. Analysis favors quantum numbers of I^G(J^P)=1^+(1^+) for both states. The results are obtained with a 121.4fb^{-1} data sample collected with the Belle detector near the Upsilon(5S) resonance, at the KEKB asymmetric-energy e+e- collider.

CERN Document Server

We compute the complete two-loop O(alpha) Wilson coefficients relevant for radiative decays of the B meson in the SM. This is a necessary step in the calculation of the O(alpha alpha_s^n ln^n m_b/M_W) corrections and improves on our previous analysis of electroweak effects in B -> X_s gamma. We describe in detail several interesting technical aspects of the calculation and include all dominant QED matrix elements. In our final result, we neglect only terms originated from the unknown O(alpha alpha_s) evolution of the Wilson coefficients and some suppressed two-loop matrix elements. Due to the compensation among different effects, we find that non-trivial electroweak corrections decrease the branching ratio by about 3.8% for a light Higgs boson, in agreement with our previous analysis. As in [1], the corresponding SM prediction for the branching ratio with E_gamma > 1.6 GeV is (3.60 +- 0.30) x 10^-4.

CERN Document Server

The $\\bar{K}N$ system at threshold is a sensitive testing ground for low energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we have measured the $K$-series x rays of kaonic hydrogen atoms at the DA$\\Phi$NE electron-positron collider of Laboratori Nazionali di Frascati, and have determined the most precise values of the strong-interaction energy-level shift and width of the $1s$ atomic state. As x-ray detectors, we used large-area silicon drift detectors having excellent energy and timing resolution, which were developed especially for the SIDDHARTA experiment. The shift and width were determined to be $\\epsilon_{1s} = -283 \\pm 36 \\pm 6 {(syst)}$ eV and $\\Gamma_{1s} = 541 \\pm 89 {(stat)} \\pm 22 {(syst)}$ eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy $\\bar{K}N$ interaction.

International Nuclear Information System (INIS)

We have measured the redshift evolution of the density of Lyman limit systems (LLSs) in the intergalactic medium over the redshift range 0 < z < 6. We have used two new quasar samples to (1) improve coverage at z #approx# 1, with GALEX grism spectrograph observations of 50 quasars with 0.8 < z_e_m < 1.3, and (2) extend coverage to z #approx# 6, with Keck ESI spectra of 25 quasars with 4.17 < z_e_m < 5.99. Using these samples together with published data, we find that the number density of LLS per unit redshift, n(z), can be well fit by a simple evolution of the form n(z) = n_3_._5[(1 + z)/4.5]"#gamma# with n_3_._5 = 2.80 #+-# 0.33 and #gamma# = 1.94"+"0"."3"6_-_0_._3_2 for the entire range 0 < z < 6. We have also reanalyzed the evolution of damped Ly#alpha# systems (DLAs) in the redshift range 4 < z < 5 using our high-redshift quasar sample. We find a total of 17 DLAs and sub-DLAs, which we have analyzed in ...

CERN Document Server

We report a study of $B\\to (J/\\psi \\gamma) K$ and $B\\to (\\psi' \\gamma)K$ decay modes using $772\\times 10^{6}$ $B\\bar{B}$ events collected at the \\Upsilon(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+ e^-$ collider. We observe $X(3872) \\to J/\\psi \\gamma$ and report the first evidence for $\\chi_{c2} \\to J/\\psi \\gamma$ in $B\\to (X_{c\\bar{c}}\\gamma) K$ decays, while in a search for $X(3872) \\to \\psi' \\gamma$ no significant signal is found. We measure the branching fractions, $\\mathcal{B}(B^{\\pm} \\to X(3872) K^{\\pm}) \\mathcal{B}(X(3872) \\to J/\\psi\\gamma)$ $=$ $(1.78^{+0.48}_{-0.44}\\pm 0.12)\\times 10^{-6}$, $\\mathcal{B} (B^{\\pm} \\to\\chi_{c2} K^{\\pm})$$=$ $(1.11^{+0.36}_{-0.34} \\pm 0.09) \\times 10^{-5}$, $\\mathcal{B}(B^{\\pm} \\to X(3872) K^{\\pm}) \\mathcal{B}(X(3872) \\to \\psi'\\gamma)$ $<$ $3.45\\times 10^{-6}$ (upper limit at 90% C.L.) and also provide upper limits for other ...