P.Wells, 23 May 1996 Minutes of the meeting to discuss logging of energy related quantities. ----------------------------------------------------------------------- Present: M. Hildreth, G. Mugnai, G.J. Bobbink, J. Mnich, O. Callot, J. Rothberg, G. Wilkinson, A. Butterworth, E. Peschardt, J. Wenninger, R. Billen, B. Dehning, P. Wells. The aim of this meeting was to bring together some representatives from the LEP Energy Calibration working group, and the LEP Interaction Regions working group, to discuss specifically remaining problems with the logging of quantities needed to calculate the LEP beam energies. This has proved difficult in meetings of one or other working group, since information from experts in both is needed. A few people were accidentally left off the mail messages to set up this meeting, and didn't hear about it in time by the grape vine. Please forward these notes to anyone who might be interested, or just invite them to any future meeting (if it turns out to be necessary outside the normal working groups). Also - please send me any corrections or comments on these notes. ************************************************** All of the quantities needed to calculate the LEP beam energy at each IP should be logged in the LEP logging database (responsible Ronny Billen). In 1995, some information came from the LX tables, which will not exist in 1996. The aim is to get as much information as possible from the LEP measurement database in 1996, which should simplify the system. Ronny explained what changes he has already made since 1995, categorised by system. Here is a brief summary, including any important comments from the dicussion of each point, and actions to be taken (i.e. actions needed in addition to Ronny's continuing work on the data base.) (LDB = logging data base, MDB = measurement data base) RF -- The tables in the LDB are updated for new units etc. and software to obtain information from MDB is in place, but both need to be checked/tested. (A. Butterworth) The software in the tunnel to monitor communications for the processes which provide measurements to the MDB has been upgraded for 1996, and is expected to be more reliable for the SC RF. This may eventually also be needed for the Cu cavities. The frequency of updates to LDB is dynamic, and is a function of LEP mode. For LEP mode 9, the RF volts, forward and reflected powers, Qs values... should be recorded every 5 minutes. Open question: Does the status of each RF unit also have to be included in the LDB, or can this be unambiguously determined from the forward and reflected powers (which are logged). ACTION: Mike Hildreth will check for some 1995 fills whether the switches can be dervied from the powers, and will communicate the results to Guy Wilkinson and Ronny Billen. The utility of the RF groups local logging for recovering data in 1995 was emphasised. Although it is hoped not to use this system, it was suggested that some routine occasional checks that all the local hard disks are made. Energy ------ (NMR readout, flux loop etc....) 14 new NMR probes, which can be in 18 positions should be available. For 1996, instead of "snap-shots", average and rms for each NMR will be provided. NMR values should also be recorded every 5 minutes. The naming convention for the NMR's is not yet defined, and is needed to allow the LDB tables to be set up. Temperature/Pressure -------------------- There are new temperature probes associated with the new NMR's. Again a naming scheme is needed. The temperatures will be recorded with greater precision in 1996 than in 1995 (0.01 deg instead of 0.1 deg, where the expected precision of the probes is about 0.06 deg). It would be sufficient to record the temperatures only every 15 minutes. Temperatures will be picked up from a file on a new server machine (stsrv1), rather than from the MDB. BCT --- The beam current table from 1995 is already large enough to take the 1996 data. Question: Beam currents were recorded every 2 minutes in the LDB in 1995. Would once every 5 minutes be sufficient for 1996? The currents are recorded in the MDB much more frequently (4 sec), and that is where the experiments pick up information. ACTION: Ask around to find out if anyone cares! Luminosity/backgrounds ---------------------- This is almost unchanged since 1995. LEP lumi AND background will now be available per family. Information from the experiments is unchanged. Power converters ---------------- Logging of main bend currents and wigglers was unreliable in 1995, due to a known problem with two processes clashing. ACTION: Follow this up with Mike Lamont, one of who's many responsibilities is for the "measurement black box" which provides these for MDB. There are new DCCT's in point 6 which should also be logged. Orbit/Sawtooth -------------- Information which used to come from "Bormio" (an apollo) will now come from an HP. This needs to be tested. Hydrostatic Levels ------------------ These are now available to measure the tilts of the QS0's in all four interaction regions. This information was taken "offline" from the survey group database in 1995, but should be available in the MDB in 1996. Vernier Scan information ------------------------ This is missing from the LDB at present, but is available in the MDB, and was thought to have lower priority for the startup than many of the quantities already discussed. Database consistency monitor ---------------------------- Ronny also described a process which checks the quantities being recorded in the LDB. This process can be configured to watch different quantities and to check: -- the time stamp -- that the value is in a reasonable range (including relative to the previous value) It can raise alarms in the LEP control room if it finds a problem. ACTION: Guy Wilkinson will collaborate with Ronny to update this program to check the crucial quantities for calculating the energy. He will also circulate lists of these quantities and their properties to the experiments so that they can also implement monitoring in the experiment control rooms. It was noted that the experiments should be obtaining these quantities from the MDB, so only Ronny's process will be checking specifically the MDB. (Question: What about quantities such as temperature probes which come from a different place and are therefore only in the LDB, not the MDB?)