The PANDA Barrel DIRC: From design to assembly
G. Schepers, A. Belias, R. Dzhygadlo, A. Gerhardt, D. Lehmann, K. Peters, C. Schwarz, J. Schwiening, M. Traxler, Y. Wolf, L. Schmitt, M. Böhm, K. Gumbert, S. Krauss, A. Lehmann, D. Miehling, M. Schmidt, C. Sfienti, A. Ali
TL;DR
The PANDA Barrel DIRC addresses precise hadron identification for the PANDA experiment in the momentum range $1.5$ GeV/c to $15$ GeV/c, aiming for at least 3 sigma separation between pions and kaons up to 3.5 GeV/c within polar angles 22° to 140°. It combines lens-focused Cherenkov imaging using a three-layer spherical lens with La crown glass between fused silica layers, 1.2 m radiator bars, a 30 cm expansion volume, and an 8×8 MCP-PMT array read out by a DiRICH system delivering timing around 10 ps. Beam tests at CERN validated the concept with a 7 GeV/c beam achieving 5 sigma pi/p separation at 20° and agreement with simulations, supporting the 3.5 GeV/c reach. The project has moved into series production for radiator bars (Nikon) and MCP-PMTs (PHOTONIS) with extensive QA and long-term CFRP outgassing studies showing no adverse effects, and prototype mechanics and assembly paths are being prepared, including a full sector for assembly validation prior to final integration.
Abstract
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.