Beam Aperture And Emittance Growth In The Ags Booster PDF Download

IN order to achieve the design luminosity, the Superconducting Super Collider (SSC) parameter choices emphasize the preservation of the transverse emittance requiring in the collider a normalized transverse emittance of 1 [pi].mm.mrad. A stringent accelerator chain emittance budget must be maintained to achieve the final value. Budgeted emittance specifications for the Low Energy Booster (LEB) include 0.4 [pi].mm.mrad at injection and ≤ 0.6 [pi].mm.mrad at extraction. The space-charge tune shift is expected to be more than 0.5 when the rms normalized emittance of 0.4 [pi].mm.mrad at injection and the total number of particles is 1.1 × 1012 with 1 × 101° particles per bunch. Therefore, it is necessary to cope with a large tune shift and avoid emittance deterioration. We have been studying the beam emittance evolution in the LEB by a multi-particle simulation code with space-charge effects. As reported in the several papers we have obtained from the simulation some new insights into the effects which seem to explain qualitatively a cause of the emittance growth. Even quantitatively, we believe that the simulation can predict the emittance growth as a function of time quite accurately because the code includes most details of the physics processes, such as the adiabatic bunching process and acceleration in the fully 6-D phase space treatment, transverse as well as longitudinal space-charge calculations in a self-consistent manner, and intensity decrease due to particle loss. The purpose of this study is to determine quantitatively the emittance deterioration due to space-charge effects, not to find the maximum current an accelerator could accommodate. Since the charge distribution itself may not remain the same, an accurate measurement of the beam profile is an essential factor of the beam study.