LBECA -- a dual-phase xenon ionization chamber for hidden-sector dark matter search

Noble liquid dual-phase time projection chambers (TPCs), when treated as low-threshold ionization detectors, have demonstrated exceptional sensitivities to both low-mass WIMPs and certain hidden-sector dark-matter candidates. However, current xenon TPCs were not designed for optimal performance in the ionization-only search mode, and consequently exhibited excessive electron backgrounds, which limit their applications in this dark-matter search channel. The Low Background Electron Counting Apparatus (LBECA) is a newly proposed compact xenon TPC experiment, specifically designed to achieve extremely low ionization-only background rates down to the single-electron level. It aims to exploit the ultimate sensitivity of the xenon TPC technology. The technical challenges and the potential scientific reach of this experiment in both dark matter and neutrino detection will be discussed.