T-474 phone conference |
Monday 02 oktober 2006, 09:30 SLAC time, 17:30 UK timePhone number : +1 510-665-5437Meeting code : 8343 |
discussion points |
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minutes |
Minutes of the T474 phone conference, 02 Oktober 2006
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- The 10D37 magnets are basially ready to go. Ray has some intial
ideas for measurements to put on the MMF (Magnetic Measurement
Facility). He will send around a first draft which we should comment
as soon as possible. Target to return the document to MMF around
16 Oktober.
o Basically would nee integrated B.dl, which can be done with the
moving wire system. Probably would have to make this a measurement
extending to about 1 m outside of the poleshoes as the
fringefields extend pretty far. Probably usefull to investigate/
measure what effect the mirrorplates will have.
o Then also measure the field axially using hall/NMR probes, maybe
including a small volume of phase space. We can use this to 1 test
the simulations for uniformity and 2 extrapolate based upon
Nikolay's simulations to get the field further from axis...
o Need to measure the temperature coefficient of the magnets. Would
make sense to have B.dl ready and correct offline the field values
for temperature.
o Need to investigate what we will magnetise using the magnets in
the ESA...
o Want to operate the magnets at 1/10 of their max. field, so
Ray is thinking of maybe ramping them up once in saturation and
then not go beyond 10-15% of their capacity during operation.
o Ray located some stands for the magnets with some high quality
precision movers for the magnets, should be no problem to use them.
o A power supply for the magnets has been identified, and the NMR
probes should be available at SLAC.
o Note, the magnets don't have trimcoils on them.
---> Highest priority for the magnets now is getting the measurement
plan in decent shape to pass it on to MMF.
---> Ray will come up with a first draft for the document, input
will be needed.
- Zen is writing the DAQ for the magnets. As we run the magnets in
series, the control program won't care about 4 individual magnets,
but will each individual magnet will be monitored with NMR probes.
- Stray fields
Mark did some plots on stray fields, his results are on :
http://pcfj.hep.phy.cam.ac.uk:8080/slater/7
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*** -------- MAIL FROM RAY ON EARTH FIELD VARIATIONS ------- ***
Here is the info I have on earth field variations. Would you
send it on to the T474 group. I don't have such a list that
you seem to use.
Facts:
Earth's field = 24,000 to 66,000 nT
1 Gauss = 1 Oersted = 100,000 nT
1 gamma = 1 nT
Earths field has much variation mostly from sun activity. See
Figure 1 at http://www.ips.gov.au/Educational/3/1/2.
There is a peak at frequencies of hundreds of seconds at about
100 gamma = 100 nT, which is probably too small for you to see
on the flux gate. There are also variations of hundreds of nT
over larger (minutes to hours) time scale that you may be able
to see.
Check out:
http://www.ips.gov.au/Educational/3/1
http://nationalatlas.gov/articles/geology/a_geomag.html
http://www.geomag.bgs.ac.uk/earthmag.html
http://www.wdcb.ru/stp/cat1GEO.html
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- Movers :
Ray will help out with the construction of a support stand, he
thinks it is best to use the system that was used for Chris'
BPMs + encoders. The reason why the thing vibrated so much is
the design of the support stand. Bino will come up with a sketch
and send around, Ray will help with some CAD drawings.
- Alex is going to MSSL this week to fix some final stuff with the
BPM design, schematics should go to Ray. First measurments have been
done using the Al prototype. Initial results are on Alex's eLog :
https://www.hep.ucl.ac.uk/elog/Alexey's+logBook/43
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