The PANDA Barrel DIRC: From design to assembly

The Barrel DIRC counter will serve as the primary particle identification detector in the PANDA experiment, enabling high-precision hadron physics studies through antiproton-proton annihilations across a momentum range of 1.5 GeV/c to 15 GeV/c. It is designed to distinguish charged pions from kaons with a separation of at least 3 standard deviations up to 3.5 GeV/c within polar angles of 22 degrees to 140 degrees. A lens focusing is used the first time in a DIRC detector. After a successful evaluation in particle beams, the key components, i.e. radiator bars and photon sensors, were purchased and tested.

💡 Research Summary

This paper provides a comprehensive overview of the development of the Barrel DIRC (Detection of Internally Reflected Cherenkov light) detector, a critical component of the PANDA experiment. The primary objective of the PANDA experiment is to conduct high-precision hadron physics studies through antiproton-proton annihilations. To achieve this, the detector must possess exceptional particle identification (PID) capabilities, specifically the ability to distinguish between charged pions and kaons across a wide momentum spectrum, ranging from 1.5 GeV/c to 15 GeV/c.

The technical core of the research lies in the implementation of a novel “lens focusing” system, which marks a significant milestone in the history of DIRC technology. Traditionally, DIRC detectors rely on the measurement of the Cherenkov angle as light undergoes total internal reflection within radiator bars. However, the inherent spread of the Cherenkov light cone over long propagation paths can degrade the angular resolution. By introducing a lens focusing mechanism, the researchers have successfully addressed this challenge, enabling the detector to maintain a separation power of at least 3 standard deviations ($3\sigma$) for pion-kaon identification up to a momentum of 3.5 GeV/c. This precision is maintained across a wide polar angle coverage, specifically between 22 and 140 degrees.

The paper details the progression of the project from the initial design and simulation phases to the practical implementation of hardware. Following successful validation through particle beam tests, which confirmed the efficacy of the lens-focusing approach, the project has transitioned into the assembly and procurement phase. The authors report that the essential components—namely the high-quality radiator bars and the advanced photon sensors—have been purchased and are currently undergoing rigorous testing. This transition from theoretical design to the acquisition of physical components signifies a major step toward the operational readiness of the PANDA experiment, promising a new era of precision in hadronic spectroscopy and particle physics.