Speaker
Description
The Electron–Ion Collider at Brookhaven National Laboratory (BNL) will enable precision studies of the strong interaction in nucleons and nuclei. Its general-purpose detector, ePIC, is designed to support a broad physics program, which relies on robust particle identification capabilities. In the electron-going endcap, a proximity-focusing Ring Imaging Cherenkov detector (pfRICH) provides charged-particle identification, enabling pion–kaon separation at the 3$\sigma$ level for momenta up to 7 GeV/c.
The pfRICH consists of a cylindrical vessel with aerogel tiles mounted on the upstream side serving as the Cherenkov radiator. Conical mirrors installed along the vessel walls reflect Cherenkov photons onto a photosensor plane located on the downstream side, maximizing photon collection. The baseline photosensors are High-Rate Picosecond Photon Detectors (HRPPDs) developed by Incom, which offer large-area coverage with fine pixelation, high quantum efficiency, low dark count rates, and excellent spatial and timing resolution. A magnetic field test was recently carried out at BNL to evaluate HRPPD performance in field strengths and orientations expected at the location of the pfRICH. The mirror system requires high reflectivity ($\geq$ 90 %) over the wavelength range of 300–600 nm, as well as good uniformity, to minimize photon losses and preserve detection efficiency. At BNL, dedicated mirror test stands are used to measure reflectivity and uniformity, providing feedback which is used to optimize the mirror production procedure.
This talk will present the pfRICH detector design, mirror production and reflectivity characterization studies, and preliminary results from the first HRPPD magnetic-field test campaign at BNL.
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