7 research outputs found
Structure of high-lying levels populated in the Y-96 -> Zr-96 beta decay
The nature of levels of Zr below the -decay value of Y has been investigated in high-resolution -ray spectroscopy following the decay as well as in a campaign of inelastic photon scattering experiments. Branching ratios extracted from decay allow the absolute excitation strength to be determined for levels populated in both reactions. The combined data represents a comprehensive approach to the wavefunction of levels below the value, which are investigated in the theoretical approach of the Quasiparticle Phonon Model. This study clarifies the nuclear structure properties associated with the enhanced population of high-lying levels in the Y decay, one of the three most important contributors to the high-energy reactor antineutrino spectrum
Tracking of lines in spherical images via sub-Riemannian geodesics in SO(3)
In order to detect salient lines in spherical images, we consider the problem of minimizing the functional ∫0lC(γ(s))ξ2+kg2(s)ds for a curve γ on a sphere with fixed boundary points and directions. The total length l is free, s denotes the spherical arclength, and k g denotes the geodesic curvature of γ. Here the smooth external cost C≥ δ> 0 is obtained from spherical data. We lift this problem to the sub-Riemannian (SR) problem in Lie group SO(3) and show that the spherical projection of certain SR geodesics provides a solution to our curve optimization problem. In fact, this holds only for the geodesics whose spherical projection does not exhibit a cusp. The problem is a spherical extension of a well-known contour perception model, where we extend the model by Boscain and Rossi to the general case ξ> 0 , C≠ 1. For C= 1 , we derive SR geodesics and evaluate the first cusp time. We show that these curves have a simpler expression when they are parameterized by spherical arclength rather than by sub-Riemannian arclength. For case C≠ 1 (data-driven SR geodesics), we solve via a SR Fast Marching method. Finally, we show an experiment of vessel tracking in a spherical image of the retina and study the effect of including the spherical geometry in analysis of vessels curvature