Advanced light source's approach to ensure conditions for safe top-off operation

Tracking study for top-off safety validation at SSRL

“…Similar to ALS [2], our tracking simulation is limited to the horizontal plane. Only horizontal apertures are taken credited for.…”

“…Therefore it is impossible to specify the allowable phase space distribution because too many parameters are involved. This is the reason the forward tracking approach was not preferred at the other labs [2,4].…”

“…Top-off operational mode has become a trend for existing and planned third-generation storage ring light sources for the many benefits such as increased average brightness, improved thermal stability and elimination of the interruption to user experiments due to traditional injection [1,2]. Unlike the traditional decay mode injection which happens a few times a day and during which the photon beamline shutters are closed, top-off mode injection requires photon beamline shutters to remain open during injection and occurs much more frequently, from once every 5 seconds to once every 30 minutes.…”

“…Studies at ALS and SSRL [2,3] have shown that a single injected electron pulse that enters the photon beamline and exits the radiation shield wall would cause unacceptable radiation doses on the experimental floor. For the protection of users and experimental equipment, it is hence a prerequisite for top-off operation to establish controls that absolutely prevent such occurrences.…”

“…Similar to other facilities such as ALS and APS [2,4], tracking simulations were conducted at SSRL to identify the control measures, define the specifications and prove the radiation safety. However, a different approach toward the proof of safety is taken at SSRL.…”