Summary notes of the CMS solenoid stray field meeting with S. Russenschuck on 16/01/2009
Present: MG, SR, YS, FZ
Discussion
SR presented the original CMS solenoid layout together with the simulated magnetic field (the three curves refer to the solution neglecting the iron, the iron contribution, and the total field). The "bump" in the total field corresponds qualitatively to the measured situation.
SR has introduced the cavern and the tunnel
(armed concrete structure) including also a rough model of the
triplets. A sketch of
the field lines in the triplets' region was produced. The
magnetic field in the cavern was computed, and
the differences with respect to the previous case are rather small (upper
plot). The lower plot reports the field in the triplets' area (the origin of
the horizontal axis is not the same as the previous plot).
The situation in the triplets' area was also
simulated. The upper plot represents the radial component of the field at
two different radii. A more quantitative analysis is needed to extract the
actual dependence of the radial component on R. It is worth stressing that
the order of magnitude of 2 mT for the transverse field is in agreement with
the measurements. The lower plot represents the axial component of the
field. It is clearly seen that the behaviour of the field in front of the Q1
is in rather good agreement with the measurements (about 10 mT in the
pick-up region and 26 mT just in front of Q1). Inside the triplets the
shielding is complete and no longitudinal field is present. The origin of
the horizontal scale is not the same between the plots for the
The following actions were decided:
YS will define three solenoids to be installed in the triplets' region: they will be used for initial tracking simulations, while waiting for the more details on the behaviour of the transverse field component (in case non-linear components will have to be included this will entail changes in the tracking codes).
The next meeting will be in two weeks.
Last update: 19-January-09
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