Constraints on Cosmic-Ray Acceleration
and Transport from Isotope Observations
M. E. Wiedenbeck$^{1}$, W. R. Binns$^{2}$, E. R. Christian$^{3}$,
A. C. Cummings$^{4}$, J. S. George$^{4}$, P. L. Hink$^{2}$,
J. Klarmann$^{2}$, R. A. Leske$^{4}$, M. Lijowski$^{2}$,
R. A. Mewaldt$^{4}$, S. M. Niebur$^{2}$, E. C. Stone$^{4}$,
T. T. von Rosenvinge$^{3}$, and N. E. Yanasak$^{4}$
$^{1}$ Jet Propulsion Laboratory, Pasadena, CA, USA
$^{2}$ Washington University, St. Louis, MO, USA
$^{3}$ NASA/Goddard Space Flight Center, Greenbelt, MD, USA
$^{4}$ California Institute of Technology, Pasadena, CA, USA
The Cosmic Ray Isotope Spectrometer (CRIS) on ACE is providing
isotopically-resolved measurements of essentially all nuclides in the
range 2$\le$Z$\le$30 at energies of a few hundred MeV/nucleon. In most
cases, statistics are sufficient to permit investigations of the energy
dependence of the composition as well. This data set is being used
to address a variety of topics related to the acceleration and
transport of galactic cosmic rays. The elemental source composition
is being investigated to probe the fractionation process that leads to
the preferential enhancement of refractory (or low-FIP) elements in
the accelerated material. Radioactive isotopes are being used to
determine the residence time of nuclei in the interstellar medium
before acceleration to high energies and the confinement time of the
accelerated particles prior to escape from the Galaxy. Electron-
capture secondary nuclides are being used as indicators of energy-
changing processes that may affect the cosmic ray spectra after the
main phase of acceleration has occurred. Stable secondaries are being
studied for the information they can provide on the distribution of
the matter traversed by cosmic rays during transport. We will discuss
recent progress that has been made in a number of these areas through
the use of ACE/CRIS data.