Herr, Werner

Miles, J

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COCU - A CLOSED ORBIT CORRECTION PACKAGE FOR SPS ANDLEPW. Herr and J. MilesCERN, Geneva, SwitzerlandAbstractThe closed orbit correction package COCU (Closed Orbit Correction Utilities)was built for SPS and LEP using well known techniques and algorithms [1,2].The procedures are driven by input data and no assumptions on the machineare made, allowing its application to any circular machine and it is now usedat various accelerators in the world in identical form [3]. It is written in an en-tirely modular form, thus allowing to implement additional algorithms easily.The sequencing of the logically independent modules is done by a sequence ofcommands, each of which initiates a well defined action. Examples for suchactions may be the handling of input and output, definition of the desired al-gorithms, preparation of the input for the algorithms etc. An important issuewas to define a well defined data interface, independent of the machine, oper-ating system or programming language [4]. This interface is used inside theprogram to communicate data between the modules as well as for communica-tion with other processes, such as data acquisition or man machine interface.A most critical aspect was the speed of the program. At LEP with its morethan 500 beam position monitors and 300 correctors in each plane, COCU isrun in a semi-automatic way, resulting in more than 10000 complete runs permonth of LEP operation. Typically a calculation must not take longer than 1 to3 seconds. For the future LHC an orbit feedback is foreseen during the rampwith a bandwidth in the order of 1 second, a goal which we believe is well inreach with our approach.The basic design principles are presented together with an overview of themain algorithms and techniques with a bias towards those which are most fre-quently used at LEP and SPS [5].References[1] “A New Closed Orbit Correction Procedure for the CERN SPS and LEP”, D. Brandt, W. Herr, J.Miles and R. Schmidt, Nucl. Instr. and Meth., A293 (1990) 305 and CERN/SPS/89-48 (AMS)[2] “Orbit processing at LEP”, D. Brandt, P. Defert, W. Herr, J.P. Koutchouk, J. Miles, T. Risselada andR. Schmidt CERN/SL/90-70 (AP)[3] “Application user guide for SPS and LEP closed orbit correction”’, G. Crockford, V. Frammery andW. Herr, SL/Note 94-25 (OP)[4] “MOPS - A Data Management System for the LEP/SPS Control System”, W. Herr, CERN/PS/89-9(AMS) and Proc. Part.Acc.Conf. 1989, Washington D.C.[5] “Algorithms and Procedures in the Closed Orbit Correction Package COCU”, W. Herr,CERN/SL/95-07 (AP)84

COCU: a closed orbit correction package for SPS and LEP

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