T-474 phone conference
Friday 21 july 2006, 11:00 PDT, (19:00 GMT+1)Phone number : +1 604-484-8700
Meeting code : 3588386#
For the people present at VLCW06, the meeting will take place in the Fort Camp Lounge in the Gage Tower residence on the ground floor across from the reception (available from 10:300 to 14:00).
Minutes of the 21 June 2007 T474 Phone conference ------------------------------------------------- HARDWARE DISCUSSION - During the meeting some initial discussion between Mike, Yury and Stewart started about hardware needs for the future running. They agreed to have the weekly T474 phonemeetings alternate between hardware and software (analysis). We will start next week with hardware issues. By then a list will be put together with more specific requirements. The main items on this list will be : o electronics for Alex's BPM prototype (prob. use SIS ADCs again, but need to investigate whether we e.g. would want to go for new 200 MHz sampling ADCs ) o electronics for a phaselock loop for the local oscillator (LO) o magnets, contact Dubna to organise concrete involvement in terms of people and magnetic measurements o expansions to the Zygo interferometer ? Need to contact Mike Hildreth on this issue. o ... - We are currently using more than 50% of CPU power for readout, which is according to Zen I/O dominated. We need to think of ways to improve this when we'll have more hardware channels to read out. Maybe contact Zen to have the data being stored in binary format instead of ASCII. This will require some effort in LabVIEW programming. - Some discussion took place on having a the local oscillator phase locked. It was agreed that this would be the preferred method to take care of the phase systematics compared to doing it by corrections in the analysis software. To control the phaselock loop, one could think of purchasing a NI DAC card which can easily be setup and controlled under LabVIEW and doesn't cost much money. This needs to be investigated, need to come up with a list what is needed by next weeks phonemeeting. - Mike brought up the issue of temperature stability, need to think wether it makes sens to move all the electronics to the same place where the temperature is stable (as e.g. downstairs in the end station ?) - We also want to think of extending the ground vibration measurements that were done by Filimon and Mike A. last summer. Especially measuringing vibrations on the SPEAR girders would be usefull. Stewart brought up the idea that we need to define a default set of positions where to take measurements. It's important that these positions are still easily accessible after the magnets have been installed so we can compare vibration before and after installation of the magnets. It would be good to have a student work on this, e.g. Mahsa, Yury's new student would be a good candidate. These measurements can take place during 2 weeks somewhere in August. The installation of the magnets can be simulated and measured by hooking up some cooling water as this will probably be the biggest source of vibration. Once this is measured we can decide whether we eventually need making changes to the cooling water system in terms of mechanical stability. - Stewart brought up the issue of the large vibration on BPM4 and was wondering whether there might be a holding current on the stepper motors. It might be possible to lock it better into position. Or possibly move it and then shut of the power. - Mike Woods and Michele met with people that do magnetic measurements at SLAC. We need to dicide on where/how/how many NMR probes. And which techniques we will use for the magnets. Need to take into account that because of the length of the magnets, fringe fields might be very important. The idea is to run the 4 magnets in series from the same power supply. We need to think what we need in terms of o controllers for the magnets (+ what kind of controller do we want?) o cable plant Should add these items to the list of the hardware meeting next week. - Need to monitor the stray fields inbetween the magnets as there is quite some iron present in the girders. So we'll have to install some flux-gate magnetometers to monitor the effect of the field from the dipoles on the stray fields. ANALYSIS DISCUSSION - Need to come up with a list of good runs and discriptions (Filimon) - Need to define a standard set of dataquality cuts (Stewart) o cuts on the PMT spil counter signals o klystron trips (eg. using energy BPM) o cuts on performance of the feedback system o charge fluctuations (compare signals of Q cavities) Would be good to have some kind of data quality bitpattern with all the different cuts represented by indidivual bits, one can cut on or use in a bitmask. - Need to figure out whether the calibrations can be improved by means of some kind of regression analysis. (Mark ?) Mike brought up the issue that it would be nice to have someone check temperature variations during calibrations as well together with a "historical" calibration plot to see how much the scales change over time and thus figure out how frequent we would need calibration. - The plan is to have some runs reprocessed soon and try to get rid of the phase systematics by applying an second gaussian filter. With the reprocessing this would also include the VSAM data. - We need a webpage or some form of documentation with exactly which is what in the datafile. - We need a timetag for the datafiles. Currently only the absolute time is written at the beginning of the runfile with minute precision. Mike suggested maybe to read out something called the "PMON" which is some kind of pulse-id counter. - In terms of optics, we need to come up with a plan on what to do. Running with a waist at the center of the chicane proved to difficult in the current optics setup. The quadrupole magnets seem to be steering too much. So we need to figure out whether we have to align them or decide upon a different optics set ? - Someone needs to have a look to the raw signals from Chris' BPMs that were taken with Zen's scope-vi. - Next meeting will be on thursday, July 27th at 17:00 UK time, 09:00 PST. Details will be sent later to the list.