A Second EIC Detector: Physics Case and Conceptual Design

TL;DR

This report advocates for a second general-purpose detector at the EIC, presenting a conceptual design, physics case, and technology assessments to enhance the scientific potential and complementarity of the existing detector.

Contribution

It develops a realistic, complementary detector concept for the EIC, identifying innovative technologies suitable for future deployment and broadening the EIC physics program.

Findings

Proposed a second EIC detector concept with unique physics capabilities.

Identified emerging technologies for future detector development.

Provided a comprehensive physics case and design outline for the second detector.

Abstract

This document is the closeout report for LDRD 23-050, a type-A LDRD project awarded in FY2022 under the title "A Second EIC Detector: Physics Case and Conceptual Design". The project was motivated by the strong interest within the EIC community in a second general-purpose detector and interaction region, and by the recognition that such a detector is essential to fully exploit the scientific potential of the EIC over its multi-decade lifetime. The key goals of the LDRD were to (i) strengthen the case for a second EIC detector, building on the community Yellow Report; (ii) develop a realistic detector concept complementary to the project detector, ePIC, in terms of physics reach, precision, and control of systematics; and (iii) broaden the overall EIC physics program. Since a possible second detector is expected to be realized with a delay of several years relative to the first detector, the project explicitly aimed at identifying technologies that are not yet sufficiently mature for ePIC but could be deployed on the later timescale of a second detector, thereby providing genuine complementarity and room for innovation. As envisioned in the original proposal, the expected outcome was a document detailing the physics potential and requirements of a second EIC detector, accompanied by a conceptual design and an outline of the remaining R&D needs. This report summarizes progress toward these goals, consolidating the physics studies, detector concepts, and technology assessments developed under this LDRD, and situating them within the broader context of worldwide detector R&D. Despite evolving EIC priorities and the effort devoted to ePIC, the work documented here is intended to provide a foundation and reference for future efforts toward a second detector. We hope this report will serve as a useful guide for colleagues advancing this program in the near- and mid-term future.