The Intermediate Silicon Tracker Detector for sPHENIX

A new barrel-type silicon detector has been constructed in the central rapidity region of the sPHENIX experiment as part of its charged-particle tracking system. The detector, referred to as the intermediate silicon tracker (INTT), provides single-event timing capability and contributes to charged-particle tracking in combination with the silicon-pixel vertex detector and the time-projection chamber. The INTT consists of two cylindrical barrels with full azimuthal coverage. The inner and outer barrels comprise 24 and 32 silicon strip ladders, respectively. Each ladder consists of four silicon strip sensors, covering the pseudorapidity range $|η| < 1.07$ for collision vertices within $\pm~10$ cm along the beam axis, at radial distances between 72 and 103 mm. The INTT has been fully integrated into the sPHENIX data acquisition system, with detector signals processed by eight FELIX servers. Continuous data taking is enabled by a streaming readout mode, in which detector data are accumulated without hardware triggers, while a conventional trigger-based mode is also supported. The detector achieves stable operation, small inactive area, and high efficiency, providing precise timing, tracking, and vertexing performance during the collection of beam-beam collision data.