  For the future intensity increase of the fixed-target beams in the CERN
accelerator complex, a barrier-bucket scheme has been developed to reduce the
beam loss during the 5-turn extraction from the PS towards the SPS, the
so-called Multi-Turn Extraction. The low-level RF system must synchronise the
barrier phase with the PS extraction and SPS injection kickers to minimise the
number of particles lost during the rise times of their fields. As the RF
voltage of the wide-band cavity generating the barrier bucket would be too low
for a conventional synchronisation, a combination of a feedforward cogging
manipulation and the real-time control of the barrier phase has been developed
and tested. A deterministic frequency bump has been added to compensate for the
imperfect circumference ratio between PS and SPS. This contribution presents
the concept and implementation of the synchronised barrier-bucket transfer.
Measurements with high-intensity beam demonstrate the feasibility of the
proposed transfer scheme.
