Comparing the behavior of simulated proton synchrotron radiation in the arcs of the LHC with measurements

In previous work it was shown that at high proton-beam energies, synchrotron radiation is an important source of beam-screen heating, of beam-related vacuum pressure in- crease, and of primary photoelectrons, which can contribute to electron-cloud formation. We have used the Synrad3D code developed at Cornell to simulate the photon distribu- tions in the arcs of the LHC, HL-LHC, and FCC-hh. In par- ticular, for the LHC we studied the effect of the ‘sawtooth’ chamber. In this paper, specific results of the Synrad3D simulations are compared with simulations by another code, Synrad+, developed at CERN, and with experimental data from a synchrotron-light beam line at BESSY II for actual LHC vacuum-chamber samples