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TY - CONF AU - Sounas, A. AU - Gąsior, M. AU - Lefèvre, T. ED - Schaa, Volker RW TI - BPM Technologies for Quadrupolar Moment Measurements J2 - Proc. of HB2018, Daejeon, Korea, 17-22 June 2018 C1 - Daejeon, Korea T2 - ICFA Advanced Beam Dynamics Workshop T3 - 61 LA - english AB - Quadrupolar moment measurements based on electromagnetic pick-ups (PU), like BPMs, have attracted particular interest as non-intercepting diagnostics to determine the transverse beam size. Here, the second-order moment, which contains information about the beam size, is extracted from the BPM electrode signals. Despite the simplicity of the concept, quadrupololar measurements have always been challenging in practice. This is related to the fact that the quadrupolar moment constitutes only a very small part of the total PU signal, which is dominated by the contributions of beam intensity and position. In this study we discuss the limitations of absolute quadrupolar measurements if applying traditional BPM technologies, and we propose a new approach to efficiently overcome them via movable PUs. Moreover, we highlight the potential use of BPMs as an emittance measurement system during the energy ramp at synchrotrons by performing differential quadrupolar measurements, which show a remarkably higher accuracy than absolute measurements. Dedicated studies using different types of BPMs in the Large Hadron Collider (LHC) at CERN demonstrated promising results. PB - JACoW Publishing CP - Geneva, Switzerland SP - 399 EP - 403 KW - emittance KW - pick-up KW - factory KW - multipole KW - electron DA - 2018/07 PY - 2018 SN - 978-3-95450-202-8 DO - 10.18429/JACoW-HB2018-THA1WE03 UR - http://jacow.org/hb2018/papers/tha1we03.pdf ER -