17 research outputs found
Effect of Coulomb Forces on the Position of the Pole in the Scattering Amplitude and on Its Residue
Explicit expressions of the vertex constant for the decay of a nucleus into
two charged particles for an arbitrary orbital momentum are derived for the
standard expansion of the effective-range function , as well as when
the function has a pole. As physical examples, we consider the bound
state of the nucleus and the resonant states of the nuclei
He and He in the s-wave, and those of and
in the p-wave. For the systems and the pole
trajectories are constructed in the complex planes of the momentum and of the
renormalized vertex constant. They correspond to a transition from the
resonance state to the virtual state while the Coulomb forces gradually
decrease to zero.Comment: 17 pages, 5 figure
Non-destructive search for interstellar dust using synchrotron microprobes
Here we describe the critical role that synchrotron X-ray and infrared microprobes are playing in the search for interstellar dust in the Stardust Interstellar Dust Collector (SIDC). The samples under examination are submicron particles trapped in low-density aerogel. We have found that the spatial resolution, energy range, and flux capabilities of the FTIR beamlines 1.4.3, ALS, and U2B, NSLS; the XRF microprobes ID13 and ID22NI, ESRF and 2-ID-D, APS; and the STXM beamline 11.0.2, ALS are ideally suited for studying these tiny returned samples. Using nondestructive, coordinated analyses at these microprobes, we have been able to eliminate most candidates as likely samples of interstellar dust. This in itself is a major accomplishment, since the analysis of these tiny samples is technically extremely challenging