Simulation study of a beam-loss scenario: Top-up mode in
                           synchrotron operation

                  Asm Sabbir Ahmed, Mohamed Benmerrouche
  Canadian Light Source Inc. (CLSI), University of Saskatchewan, SK, Canada

Abstract:
Inside the storage ring of a synchrotron light source, the beam current
continually decays down and requires a routine injection of electrons into the
beam in order to restore the beam current. In traditional operation mode, called
"decay-mode" the user beam time is interrupted during the injection period.
As an alternative, the "top-up" injection mode is adopted in many
synchrotron facilities where electrons are frequently injected into the storage
ring to keep a steady current. The top-up operation mode facilities the beam
user by providing brighter synchrotron light with minimal thermal variation.
From a radiation safety point of view, there is a difference between "decay"
and "top-up" mode. In decay mode, the safety shutters for each beam line
remain closed during the injection period, ensures that the injected beam cannot
stream through the beam line. During the top-up mode, the safety shutters remain
open, raises safety issues of possible beam losses through the beam lines. The
proposed simulation study subjects to the modeling of one of the beam ports
currently available at the Canadian Light source and to study possible beam loss
scenarios that may happen during the top-up operation. The study will be
performed both with MCNP (Monte Carlo N Particle) and FLUKA, in order to find an
agreement between the results achieved from two programs.