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TY - CONF AU - Patecki, M. AU - Kubo, K. AU - Kuroda, S. AU - Naito, T. AU - Okugi, T. AU - Tauchi, T. AU - Terunuma, N. AU - Tomás, R. AU - White, G.R. AU - Zimmermann, F. ED - Henderson, Stuart ED - Akers, Evelyn ED - Satogata, Todd ED - Schaa, Volker R.W. TI - Contribution of Optical Aberrations to Spot-size Increase with Bunch Intensity at ATF2 J2 - Proc. of IPAC2015, Richmond, VA, USA, May 3-8, 2015 C1 - Richmond, VA, USA T2 - International Particle Accelerator Conference T3 - 6 LA - english AB - A primary goal of ATF2 (Accelerator Test Facility) is to demonstrate a low vertical beam size at the interaction point (IP) of about 37 nm. Measurements over the past years indicate that the ATF2 vertical beam size strongly rises with bunch intensity. Several different origins of this increase are considered, e.g. wakefields occurring between the ATF damping ring and the IP, and/or intrabeam scattering (IBS) causing the increase of transverse emittances and energy spread in the damping ring with the increase of the bunch intensity. In this paper we address the second possibility. Past measurements and simulations of the IBS effects in the ATF are used to model the intensity-dependent initial emittances and energy spread at the entrance of the final focus. Particle tracking simulations predict the IP vertical beam size growth expected from the known optical aberrations for initial beam parameters corresponding to varying bunch intensities. Comparing simulation results with emittance measurements at different locations allows us to draw some conclusions about the impact of IBS in the damping ring on the IP spot size, and about possible single-bunch wakefields in the ATF2. PB - JACoW CP - Geneva, Switzerland SP - 455 EP - 458 KW - emittance KW - damping KW - optics KW - extraction KW - simulation DA - 2015/06 PY - 2015 SN - 978-3-95450-168-7 DO - 10.18429/JACoW-IPAC2015-MOPJE065 UR - http://jacow.org/ipac2015/papers/mopje065.pdf ER -