ALMA Band 8 version2 receiver upgrade project

The Atacama Large Millimeter/submillimeter Array (ALMA) Wideband Sensitivity Upgrade (WSU) will at least double the observation bandwidth and improve the sensitivity and scientific capabilities. The WSU requires upgrading the receiver front-end and the associated analog and digital electronics including the correlator, as well as the ALMA software. In line with the WSU mission, the National Astronomical Observatory of Japan (NAOJ) initiated the ALMA Band 8 (385-500 GHz) version2 receiver upgrade project, aiming to build an upgrade of the currently existing receiver cartridge with a substantially improved second-generation version. This project originated from significant advances in receiver technologies and a variety of our previous wideband studies in the last decade. This paper briefly summarizes an overview of this project, scientific needs in this frequency range, and the technical readiness and challenges for critical components and subsystems.