Xiao, B. P. Mernick, K. Severino, F. Smith, K.S. Xin, T. Xu, W. Zaltsman, A. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-MOPO006 English 47-49 MOPO006 cavity resonance booster HOM cathode Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-MOPO006 http://jacow.org/linac2018/papers/mopo006.pdf The Linac of Low Energy RHIC electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with peak-to-peak dp/p less than 7·10⁻⁴. The booster cavity is the major accelerating component in LEReC, which is a 0.4 cell cavity operating at 2 K, with a maximum energy gain of 2.2 MeV. It is modified from the Energy Recovery Linac (ERL) photocathode gun, with fundamental power coupler, pickup coupler and HOM coupler close to each other. Crosstalk effect in this cavity is simulated and measured. Correction method is proposed to meet the energy spread requirement.