Magnets :
- increase of cost due to bigger radius quantified considering, active weight and power consumption (cost of the power supply not yet considered)
- B3 due to Eddy current for stainless steel pipe is negligible, for copper is about 3-5 units for 1 mm copper coating. The sum of the two can be considered for stainless steel pipe laminated with copper. Adding hysteresis effect presented in Rome gives ~10 units at 20 GeV… for 60 mm diameter. It increases a bit for larger pipe.
Collective effect:
- Nb =2.4 10^10 is a bit higher than the threshold for TMCI instability at 20 GeV ttbar nominal lattice, with 50 mm diameter copper pipe.
- Higher Momentum compaction, or bigger radius or reducing Nb could mitigate this
- Energy spread and bunch length at injection can be decoupled by bunch compressor/decompressor in the pre-injector to Booster transfer line
- Is then wigglers needed ? The simulations so far do not consider the interplay with IBS that can increase actual energy spread and bunch length
- Include impendence budget on the gitlab repository of the optics: https://gitlab.cern.ch/acc-models/fcc
acc-models-fcc · GitLab
GitLab Enterprise Edition
gitlab.cern.ch
(booster optics as well)
Vacuum:
- Without NEG coating, backeout and any other treatment vacuum will be poor in the Booster and will require a huge number of pumping bellows.
- Need to quantify impact of radius and of failure of pumping bellows.
- Need to quantify cost of NEG coating
- Need to quantify interplay of NEG coating and impedance with and without copper
