WG-A, August 27, 2007
Present: Sanuki, Sugimoto, Markiewicz, Seryi, Osborne, Settles, Kozanecki, Damerell, Krempetz, Parker, Gaddi, Meyners, Buesser, Oriunno, Tauchi, Keller, Morse, Guarino, Breidenbach (+possibly other colleagues)
Marty Breidenbach discussed various basic assumptions, see the slides for details. Particular comments or discussion are noted below:
With respect to magnetic field, Ron Settles mentioned that one need to make a map also down in the hall or at least to have cross-check. Marty: NMP probes may be inserted permanently to monitor and check the field.
Witold: ATLAS solenoid field mapping -- reproducibility was calculated to depend mostly on endcap opening-closing, rather than on what happen during move from surface to the hall. For ATLAS, made simulations that several mm of error in endcap placement would be OK.
Osborbe, with respect to question on earlier availability of collider hall, mentioned that to have it by 3 years earlier would be not possible.
Witold: if detector assembly is underground, forced to wait; if on surface -- decoupled.
Question with respect to very shallow site -- where are the klystrons? Marty: in the parallel trench. Segments of beamline prefabricated together with tunnel walls and installed in place.
For the beam dump, assume that it is deeper (vertical bend ?)
With respect to radiation in ILC w.r.to LHC, Marty: 10krad was typically used as design goal for places where pairs hit.
With respect to vibrations, Marty mentioned ~2x2x20m shielding blocks for MARK, which spanned 20m, and by walking on them one could excite large low frequency oscillations.
With respect to the question if one can move solenoid energized, Gaddi mentioned two issues: first is with bringing the power to the solenoid; second issue is that moving energized solenoid would cause vibrations and deformations, provoking large magnetic forces, that may increase possibility of the quench.
Witold- also dump resistors are an issue. Marty: refer to Craddock's design of water pressurized resistors which are smaller than traditional.
(resistors discussed at http://ilcagenda.linearcollider.org/conferenceDisplay.py?confId=2122 )
Witold: decay time of solenoid is about 2hrs, maybe can start preparing the move while it is still decaying.
Comment: could the field be decreased to a half (to decrease energy and possibility of quench), and then solenoid moved?
Ron Settles suggested to include (in the workshop discussion program) discussion about experience of maintenance of detectors in the past and to discuss what need to be foreseen for the future. Ron would collect the data and prepare discussion.
Norbert Meyners discussed Marty's questions and gave comments. See slides for details.
With respect to the requirement not to have shaft above the garage position, Mary asked is this because of safety and not dropping down the load? N.M: yes.
Sugimoto-san presented discussion of FD support and how it connects to vibration or the hall width, see slides for details.
Question with respect to slide 2. Marty: why the whole detector cannot be shifted to the left for this operation? Sugimoto-san: such operation may need to be performed often, like every half a year (refer to experience at Belle?) and this is not for TPC access but for access to inner detectors. If detector will be moved to the left, one would need magnetic mapping every time. Marty: frequency of needed access seem surprisingly high.
Comment with respect to slide 5, where is is mentioned that there is no way for a person to run away from one side of the detector to the other side: a small passage tunnel may (should) go along the side of the hall, and provide this escape.
Question with respect to 2x4cm 2m SiD-like rails that deflect too much as mentioned by Sugimoto-san: what is foreseen in SiD and does such scheme work? Answer: this is under consideration.
Action needed: still need to understand better the SiD-like FD support scheme (deflection of rails in opened position?) and compatibility with GLD-like scheme of support from support tube.
