Search results for "COUPLING"

Longitudinal dynamics of multiple conserved charges

2021

Abstract It is the goal of the RHIC BES program and the future FAIR and NICA facilities to produce compressed baryonic matter. In experiments such as these, strong gradients in baryon density are expected, and therefore the diffusion of baryon number could play a major role in the description of the fireball. The constituents of the produced matter carry a multitude of conserved charges, namely the baryon number, strangeness and electric charge, so that the diffusion currents of conserved charge couple with each other. Therefore, baryon density gradients in the above-mentioned high-density collision experiments will generate equalizing currents in all conserved charges. In common fluid dyna…

Consistent large-scale shell-model analysis of the two-neutrino ββ and single β branchings in 48Ca and 96Zr

2020

Abstract Two-neutrino double-beta-decay matrix elements M 2 ν and single beta-decay branching ratios were calculated for 48Ca and 96Zr in the interacting nuclear shell model using large single-particle valence spaces with well-tested two-body Hamiltonians. For 48Ca the matrix element M 2 ν = 0.0511 is obtained, which is 5.5% smaller than the previously reported value of 0.0539. For 96Zr this work reports the first large-scale shell-model calculation of the nuclear matrix element, yielding a value M 2 ν = 0.0747 with extreme single-state dominance. These matrix elements, combined with the available ββ-decay half-life data, yield effective values of the weak axial coupling which in turn are u…

Angular distributions in quasi-fission reactions

1986

Abstract Angular distributions for fission-like fragments were measured in the systems 50Ti, 56Fe + 208Pb by applying an off-line K X-ray activation technique. The distributions d2σ/dθdZ exhibit forward-backward asymmetries that are strongly Z-dependent. They result from a process (quasi-fission) which yields nearly symmetric masses in times comparable to the rotational period of the composite system. A method for obtaining the variance of the tilting angular momentum, K02, from these skewed, differential angular distributions is described. The results indicate that the tilting mode is not fully excited in quasi-fission reactions. The results are compared to the sum of the variances of all …

Angular distributions in quasi-fission reactions: Evidence for incomplete relaxation of the tilting mode

1985

Angular distributions of fission-like fragments have been measured for50Ti+208Pb and56Fe+208Pb collisions. Z-dependent asymmetries around Θincm= 90° preclude their interpretation in terms of compound nucleus fission with the transition state theory. Fits of the data with a simple ansatz for statistical angular momentum fluctuations (tilting) give evidence for an incomplete relaxation of the tilting mode in quasi fission reactions.

Erratum to: “A quark model analysis of orbital angular momentum” [Phys. Lett. B 460 (1999) 8–16]

2000

Electron–phonon interaction in a thin Al–Mn film

2006

Abstract Aluminum doped with manganese is an interesting novel material with applications in normal metal–insulator–superconductor (NIS) tunnel junction devices and transition-edge sensors at sub-Kelvin temperatures. We have studied the electron–phonon (e–p) coupling in a thin aluminum film doped with 1% manganese, with a measuring technique based on DC hot-electron effect. The electron temperature was measured with the help of symmetric normal metal–insulator–superconductor tunnel-junction pairs (SINIS-thermometers). Measurements show that the temperature dependence of the e–p interaction is not consistent with existing theories for disordered metals, but follows a higher power law.

Future weak lensing constraints in a dark coupled universe

2011

Coupled cosmologies can predict values for the cosmological parameters at low redshifts which may differ substantially from the parameters values within non-interacting cosmologies. Therefore, low redshift probes, as the growth of structure and the dark matter distribution via galaxy and weak lensing surveys constitute a unique tool to constrain interacting dark sector models. We focus here on weak lensing forecasts from future Euclid and LSST-like surveys combined with the ongoing Planck cosmic microwave background experiment. We find that these future data could constrain the dimensionless coupling to be smaller than a few $\times 10^{-2}$. The coupling parameter $\xi$ is strongly degener…

Coupling of single atom with localized modes associated to defects in one-dimensional photonic crystals

1998

Abstract The Hamiltonian model describing the interaction between a two-level atom with two electromagnetic localized modes in an imperfect one-dimensional photonic crystals is introduced. The possibility of generating Schroedinger-cat-like states of these defect modes is reported. The physical origin of this dynamical behaviour is pointed out.

The nuclear structure of 229Th

2002

Abstract The γ -rays following the β − decay of 229 Ac have been investigated by means of γ -ray singles and γγ -coincidence measurements using Ge detectors. Multipolarities of 40 transitions in 229 Th have been established by measuring conversion electrons with a mini-orange electron spectrometer. The half-lives of the 146.35, 164.53 and 261.96 keV levels have been measured using the advanced time delayed βγγ (t) method. The low-lying states in 229 Th and observed transition rates have been interpreted within the quasiparticle–phonon model with inclusion of Coriolis coupling. Two octupole correlated parity partner bands, with K π =5/2 ± and K π =3/2 ± , were identified in 229 Th.

gamma-hadron correlations as a tool to trace the flow of energy lost from hard partons in heavy-ion collisions

2009

High transverse momentum (P_T) gamma-hadron correlations are currently being regarded as the 'golden channel' for the study of the medium produced in ultrarelativistic heavy ion collisions by means of hard probes. This is due to several reasons, all linked to the fact that because of the smallness of the electromagnetic coupling alpha, the photon does not substantially interact with the medium and is expected to escape unmodified. Thus, a high P_T photon indicates a hard process in the collision independent of the position of the hard vertex. In contrast, there may not be a clear signal for a hard process involving strongly interacting partons if the production vertex is deep in the medium …