Kin,
2 mm discrepancy is the change in what dimension? location?
Effect of insulating vacuum and vacuum volume vented to 1 atm: ?? Question for structural engineer
Effect of temperature change: 10K [18F] shift will shift the 3500 mm diameter by 0.8 mm for 5083 aluminum.
Roberto Than
Cryogenic Systems, Collider-Accelerator Department
Brookhaven National Laboratory
Building 1005S, MS 1005S, Room 212
Upton, NY 11973-5000
Telephone: (631) 344-7165
Cell 631-487-6842
E-mail:
ythan AT bnl.gov
From: sPHENIX-magnet-l [mailto:sphenix-magnet-l-bounces AT lists.bnl.gov]
On Behalf Of Kin Yip
Sent: Friday, September 08, 2017 10:23 AM
To: sphenix-magnet-l AT lists.bnl.gov
Subject: [Sphenix-magnet-l] Differences in forces between ideal and newest survey
Hello,
After lifting the Magnet slightly, the survey came back yesterday. I talked with Matt Ilardo a couple times to understand.
It's raised a bit higher than first thought but it seems that the Lead/Non-Lead ends weren't really raised differently.
He gave us the x/y/z measurements from the ideal center (0,0,0).
So, I've used the most updated Opera model (that we changed a small part of the roof from Wuzheng Meng's original model.
[ Here, I've used the most realistic configuration that the coil is shifted 2.85 towards Non-Lead End. ]
The survey shifts (in cm) looks like in Opera (you can find the 3 nos. in cm below) :
**** COMMAND INPUT *** MODI C1=1 C2=* XCENTRE=XCENTRE+0.16038 YCENTRE=YCENTRE+1.07035 ZCENTRE=ZCENTRE+0.21175
The X/Y/Z in Wuzheng's model is slightly different from Matt's. In Opera, Z is the axial axis of the Magnet and Y is Up.
I've computed the magnetic forces on the 24-coils in all 3 directions for the original/ideal configuration and the one
corresponding to the survey results. See the attached plots. Forces are given in Newton (1 N ~ 0.2248 pound-force ).
[ The 24 coils are defined as in Wuzheng's talk:
https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Shared%20Documents/Forms/AllItems.aspx?RootFolder=%2Fsites%2FsPHENIX%2DMagnet%2FShared%20Documents%2FDr%2E%20Meng%20Wuzheng%27s%20calculations&FolderCTID=0x012000558FEE5CA7F67C49A571FA0CA2EECCD4&View={64ECB5ED-E4EB-4507-9D58-1A49DE1E644D}
]
Percentage-wise, there are more changes in X (horizontal) and Y(vertical) whereas the axial forces (in Z) have changed little.
The Magnet is sensing an upwards force (due to our upward movement), though not yet levitated :-)
Kin
PS:
(1) Both F. Karl and M. Ilardo seem to feel that the Magnet is not really locked (by the Jack ?) or rigid ... as they might see up to or about 2 mm from survey to survey etc.
(2) From the BaBar "as built" drawing, the result are quoted typically one decimal point (to 0.1 mm), or even two decimal points, eg. in our Babar server, in "Volume 6 AS BUILT DRAWINGS\6.2 COIL AND SHIELD.pdf". There is also a precision/tolerance table
("+/-") depending on how big the magnitudes are. I feel that the precisions there seem considerably smaller than what we are talking about here. So, I didn't bother adding
anything here.
