Down Selection Criteria and MDs Prior to LS3

Abstract

The operation of the LHC and the machine studies conducted during run I have provided important input for the validation of some of the choices that are at the base of the HL-LHC upgrade scenario but it has evidenced also some potential limitations. Progress has been done in their understanding but some open points remain that need to be further studied to consolidate the operational scenario and performance (e.g. stability during the squeeze and collision process, electron cloud effects with 25 ns beams). Some of the solution proposed for the HL-LHC nominal scheme like the operation of crab cavities has not been tested in hadron machines so far and possible alternative solutions have been proposed (e.g. the implementation of long range wire compensators). The required validation studies and the possible criteria for the validation and down-selection of these options will be outlined.