Minutes of the 1rst LHC Insertions Upgrade Working Group held on 5th September 2007
Present: V. Baglin, O. Brüning, S. Fartoukh, M. Giovannozzi, J.-P. Koutchouk, K.-H. Meß, R. Ostojic, V. Parma, L. Rossi, L. Tavian, E. Todesco, R. Van Weelderen, J. Kerby
Ranko first reminded the framework of the activities in which the working group is inscribed, in particular the CARE-HHH and the US-LARP collaborations which already developed and documented several ideas and proposals on how to best increase the luminosity of the LHC. Two very recent events, namely the acceptance of the "White Paper" by the CERN council and the acceptance of the "Preparatory Phase of the LHC Upgrade (SLHC-PP)" as part of the FP7 CNI, defined more precisely the budgetary boundaries in which the first phase of an LHC Upgrade project could be contained, to be ready for luminosity runs in 2013.
By order of priority, the basis for "Phase I" are an aperture upgrade of the inner triplet quadrupoles (Q1/Q2/Q3) in the ATLAS and CMS experimental insertions (IR1 & IR5), of the TAS and all other equipments related to the triplet aperture (e.g. beam line absorber, DFBX, corrector magnets, BPM, ...) and very likely of the separation dipole magnet D1 (to be confirmed), while sticking to the present "quadrupole-first" layout. The new wide aperture SC triplet quadrupoles shall be based on the present well characterized Nb-Ti technology (LHC dipole type cables). The present interface with the experiments shall not suffer strong modifications (i.e. l*= 23 m eventually shortened by 1 m leaving only 3 m for the TAS, shielding and pumping equipments up to the hard beginning of the detector located at ±19 m w.r.t. the IP). Mainly for cost reasons, the new triplet shall remain compatible with the present cooling capacity of the cryogenic system in IR1 and IR5. Finally, any minor or major modification requests of the matching section (Q4-D2 → Q7) have low priority and shall be strongly justified.
According to this strategy, Ranko then presented an non-exhaustive list of open questions, out of which the first two ones (need for beam-screens, need for changing D1) will be discussed at the next meeting.
All this defines the mandate and boundary conditions of the working group, which is to develop an upgrade scenario able to increase the design average luminosity of the LHC at least by a factor of 2, therefore to reach about 2×1034 cm2 s-1 . Since the present cryogenic system of the LHC is a priori not compatible with the ultimate LHC beam intensity, the key ingredient will be the aperture increase of the low-beta quadrupoles (and eventually D1) to be compatible with a b* of 25 cm. The working group will report in person to the LHC Project Leader and inform regularly the AT and AB management. The main deliverables are
The different members of the working group have been selected in view of their expertise and/or representativity. One member representing the AB/ATB group has still to be identified. Minutes will be sent by e-mail to the members and, for information, to the LHC project leader and the management of the AT and AB departments. The regular meetings will be organized on Thursday afternoon (16:00) every other two weeks.
2. A.O.B.
Next meeting: V. Baglin (beam-screen review), S. Fartoukh (LSS magnet aperture requirement versus b*)
S. Fartoukh and R. Ostojic