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.
Pulse-To Pulse Modulation of the Beam Characteristics and Utilization in the CERN PS Accelerator Complex
The CERN PS complex (comprising the 50 MeV Linac, the 800 MeV Booster, the 28 GeV PS and the 3.5 GeV/c Antiproton Accumulator) must deliver beams of various characteristics (e.g. energy, intensity, emittances, ejection mode) to several users, with a repetition time as low as 0.65 s. The SPS accelerator, ISR and LEAR storage rings and the 25 GeV physics experiments receive beams in a repetitive sequence, called a supercycle. The coordination is achieved by the Program Lines Sequencer (PLS) which sends to the equipment concerned (before every machine cycle) a serial message, describing the user and the characteristics of the beam. This message is created by an on-line computer using (i) previously-entered information through a series of application programs and (ii) external conditions coming from the process or the users: these signals in turn can modify the information (i) accordingly.
The potential vorticity flux through the Yucatan Channel and the Loop Current in the Gulf of Mexico
Two‐year‐long time series of current and density structure measurements across the Yucatan Channel's main section allow the calculation of the time‐dependent potential vorticity flux between the Gulf of Mexico and the Caribbean Sea, which is characterized by alternating periods of positive (cyclonic) and negative (anti‐cyclonic) vorticity influx. Periods of negative cumulative vorticity influx are related to the Loop Current extending into the Gulf of Mexico, whereas periods of positive cumulative vorticity influx relate to a Loop Current retraction, sometimes coincident with the shedding of an anti‐cyclonic eddy.