  We report observations of the acceleration and trapping of energetic ions and
electrons between a pair of corotating interaction regions (CIRs). The event
occurred in Carrington Rotation 2060. Observed at spacecraft STEREO-B, the two
CIRs were separated by less than 5 days. In contrast to other CIR events, the
fluxes of energetic ions and electrons in this event reached their maxima
between the trailing-edge of the first CIR and the leading edge of the second
CIR. The radial magnetic field (Br) reversed its sense and the anisotropy of
the flux also changed from sunward to anti-sunward between the two CIRs.
Furthermore, there was an extended period of counter-streaming suprathermal
electrons between the two CIRs. Similar observations for this event were also
obtained for ACE and STEREO-A. We conjecture that these observations were due
to a "U-shape" large scale magnetic field topology connecting the reverse shock
of the first CIR and the forward shock of the second CIR. Such a disconnected
U-shaped magnetic field topology may have formed due to magnetic reconnection
in the upper corona.
