sPHENIX MVTX Commissioning at BNL

sPHENIX is a new state-of-the-art heavy-ion physics experiment at RHIC in the past 20 years. At the center of the sPHENIX detector, the Monolithic-Active-Pixel-Sensor (MAPS) based VerTeX detector (MVTX) is a high-precision silicon pixel detector adapted from the ALICE Inner Tracking System. The MVTX provides excellent position resolution and the capability of operating in continuous streaming readout mode, allowing precise vertex determination, and recording a large data sample, both of which are particularly crucial for heavy flavor physics measurements. The MVTX has been installed to the sPHENIX detector on April 1 and passed all tests. sPHENIX has completed its first year Au + Au collision data taking from May 18 to August 1. During the run, a significant background, potentially linked to beam halo, is observed by the MVTX. Notably, ALICE also reported similar issues at the LHC in Run 2023 and found a solution with the LHC accelerator division. In addition, cosmic data were collected for calibration and alignment purposes. This presentation will cover the commissioning and performance of the MVTX detector. We will also discuss various aspects, including studies on MVTX raw data processing, beam background, noise levels, and tracking alignment.