• N. Simos, M. Fallier
  BNL, Upton, Long Island, New York

Vibration stability in third generation light sources such as the 3 GeV NSLS II under construction at BNL and which are aiming at high brightness and extremely small photon beam sizes is paramount. Movement of the magnetic elements of the accelerator lattice, and in particular when uncorrelated, will induce jitter in the beam and degrade the machine performance. The accelerator lattice response is coupled with the ring structure which in turn interacts with the site and the ground vibration field that characterizes it. Therefore, understanding this dynamic coupling between the accelerator ring structure and the site and the “filtering” effect of the interaction on both the amplitude and the spectral characteristics of the ground vibration is central towards establishing the response of the lattice. In this study, the site-ring dynamic interaction is evaluated based on the NSLS II design and site conditions using a state-of-the-art 3-D wave propagation and scattering analysis model. The study is augmented with an extensive array of measurements at the selected site as well as field studies at similar operating light source facilities.

• N. Simos, M. Fallier, T.F. Joos
  BNL, Upton, Long Island, New York

Cultural noise generated within or in the proximity of a light source facility aiming to achieve stability levels of just tens of nanometers in the electron beam and extremely small photon beams in special experimental lines could be a limiting factor towards achieving the performance goals. While operating systems within the facility are more readily identifiable as sources of vibration and cause of instabilities and they tend to be of deterministic nature so appropriate action can be taken to minimize their impact, moving-type loads such as traffic in the general vicinity or within the bounds of the accelerator facility are more of a stochastic nature and require a different approach in assessing its impact on the synchrotron facility. In this study the effect of such loads which poses both stochastic elements and a complex spectrum on the stability performance goals of the NSLS II synchrotron and its vibration-sensitive experimental lines is addressed prior to the construction of the facility. This is achieved through the synergy of a comprehensive numerical model and an array of recorded field data.