Turn-By-Turn Emittance Tracking in CesrTA with Space Charge -ctf_12wig_v4c_s2 lattice, 2.0 GeV -Modified beambeam jobs with space charge module incorporated -All scans run at 1000 particles for 100,000 turns, unless otherwise stated -Last week: scans included the tune shift resulting from space charge effects -Now: “masking” this tune shift, to have a direct comparison of one run to the next With tune shift (last week) Without tune shift (this week)

Effects of Space Charge on Vertical Emittance -Summarizing the plot on the previous page, vertical emittance after 100,000 turns was plotted against current -At 100,000 turns, currents under ~4mA have not finished damping, therefore those data points are nonphysical -Trend: space charge contribution to vertical emittance at proposed CesrTA operating current (1.25mA) will be negligible y = 5pm

Space Charge At CesrTA Operating Current (1.25mA) -As previously noted, vertical emittance has not fully damped after 100,000 turns -An additional tracking was done for 1000 particles out to 1E6 turns -y damps down to ~1E-12m -Vertical emittance damps down to roughly 1E-26 m -Conclusion: effects of space charge on vertical emittance is negligible at CesrTA operating levels