Data Requirements and Handshake for Thf CERN Antiproton Transfer Operations from the AA and PS to Client Machines

The CERN Antiproton Accumulator(AA) fulfils its role as a p¿ source for all the diverse needs at CERN ranging from a few 109 p¿´s in a single bunch for the Low Energy Antiproton Ring(LEAR) every hour or so upto 1011 p¿´s in 3 bunches for the Super Proton Synchrotron(SPS) Collider operations every 24 hours. The geographically dispersed accelerators involve large distances and proper synchronisation is mandatory for successful transfer operations. While every transfer operation needs preparatory work on all the machines involved in the chain with and without verbal communication in-between operators and control centres, an essential element has been the data exchange over the computer network linking the various processors in the PS and SPS Collider complex. This paper attempts to show some of the specialised data requirements which arose for the p¿ transfer operations and the essential software linking of various processes in different computers leading to a complete transfer operation from the AA, via the transfer lines and PS, to the SPS Collider or LEAR. For the Collider runs, the pre- and post-countdown data synchronisation and interchange involves upto a dozen computers in the PS and SPS computer networks.