Benchmarking Studies of Intra Beam Scattering for HL-LHC

The effects of Intra Beam Scattering (IBS) in the High Luminosity upgrade of the LHC (HL-LHC) will be stronger compared to effects in the present LHC because of the high intensity of the proton bunches and the new proposed optics. We present benchmarking studies carried out for the present LHC at injection and collision energies as well as HL-LHC at collision energy with the Achromatic Telescopic Squeezing optics. The results of IBS growth-rate calculations using the full Bjorken-Mtingwa formulae are compared with simplified formulae, Bane’s high energy approximation, and the Completely Integrated Modified Piwinski (CIMP) approximation. The results of calculations based on these methods carried out in Mathematica are compared with results from the codes MAD-X and ZAP.