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TY - CONF AU - Danisi, A. AU - Losito, R. AU - Masi, A. AU - Passarelli, A. AU - Salvant, B. AU - Zannini, C. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - FEM Analysis of Beam-coupling Impedance and RF Contacts Criticality on the LHC UA9 Piezo Goniometer J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - The UA9 piezo-goniometer has been designed to guarantee micro-radians-accuracy angular positioning of a silicon crystal for a crystal collimation experiment in the LHC, and to minimize the impact on the LHC beam-coupling impedance. This paper presents a Finite Element Method (FEM) study of the device, in both parking and operational positions, to evaluate its impact on the LHC impedance budget. The study has been a progressive simulation work, started from the simplification of the original detailed design, and aimed at highlighting the effect of single details (e.g. objects in confining chambers) on the longitudinal and transverse components of beam-coupling impedance. In addition, the shielding contribution of the RF gaskets has been carefully evaluated, with the objective to assess the consequences for operation in case of their failure. Sensitivity analyses to simulation parameters are also performed, in order to test the FEM model robustness. A final word is drawn on the overall device impedance criticality. PB - JACoW CP - Geneva, Switzerland SP - 1692 EP - 1694 KW - impedance KW - simulation KW - resonance KW - experiment KW - coupling DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-TUPRI054 UR - http://jacow.org/ipac2014/papers/tupri054.pdf ER -