The "xpDIRC" Concept for the Next-Generation PID Detector*

The Electron-Ion Collider (EIC), the next flagship facility in nuclear physics, will feature two interaction regions and potentially two full-scale detectors. The first, ePIC, employs the hpDIRC (High-Performance DIRC) for charged-particle identification up to 6 GeV/c, now entering its construction phase.

We present the xpDIRC (extreme-Performance DIRC), a next-generation concept developed with the future EIC Detector-2 in mind. Simulation studies isolating and disabling key effects like chromatic dispersion or multiple scattering show that π/K separation up to 10 GeV/c is achievable. The initial xpDIRC introduces a hybrid optical design coupling narrow fused-silica bars via compound lenses to a wide plate and compact prism expansion volume, significantly enhancing focusing precision.

The new geometry also enables the use of SiPMs as an alternative to MCP-PMTs. Simulations demonstrate strong performance and robustness even with realistic dark-count rates, establishing SiPMs as a promising technology for future Cherenkov detectors. Experimental validation of the xpDIRC is planned within the next three years.