First-Ever Deployment of a SiPM-on-Tile Calorimeter in a Collider: A Parasitic Test with 200 GeV $pp$ Collisions at RHIC

TL;DR

This paper reports the first deployment and testing of a SiPM-on-tile calorimeter in a collider environment at RHIC, demonstrating its feasibility and providing insights for future detector designs at EIC and other applications.

Contribution

It presents the first-ever deployment, commissioning, calibration, and long-term operation of a SiPM-on-tile calorimeter in a collider setting, with detailed performance analysis.

Findings

Calibrated the detector using minimum-ionizing particles during beam conditions.

Achieved a good match between measurements and Geant4 simulations.

Demonstrated the detector's capability to operate in a high-radiation collider environment.

Abstract

We describe the testing of a prototype SiPM-on-tile iron-scintillator calorimeter at the Relativistic Heavy Ion Collider (RHIC) during its 200 GeV $pp$ run in 2024. The prototype, measuring $20 \times 20 \, \text{cm}^{2}$ and 24 radiation lengths in depth, was positioned in the STAR experimental hall, approximately 8 m from the interaction point and 65 cm from the beam line, covering a pseudorapidity range of about $3.1<\eta<3.4$. By using the dark current of a reference SiPM as a radiation monitor, we estimate that the prototype was exposed to a fluence of about $10^{10}$ 1-MeV $n_{\mathrm{eq}}$/cm$^2$. Channel-by-channel calibration was performed in a data-driven way with the signature from minimum-ionizing particles during beam-on conditions. A Geant4 detector simulation, with inputs from the Pythia8 event generator, describes measurements of energy spectra and hit multiplicities reasonably well. These results mark the first deployment, commissioning, calibration, and long-term operation of a SiPM-on-tile calorimeter in a collider environment. This experimental campaign will guide detector designs and operational strategies for the ePIC detector at the future EIC, as well as other applications.