Trap-integrated fluorescence detection based on silicon photomultipliers in a cryogenic Penning trap

TL;DR

This paper introduces a novel fluorescence detection system using silicon photomultipliers operated at cryogenic temperatures within a Penning trap, enabling efficient ion detection with limited optical access.

Contribution

It demonstrates the integration of SiPMs into a cryogenic Penning trap for fluorescence detection, a significant advancement over traditional room-temperature methods.

Findings

Dark count rate below 1/s at 4 K

Detection efficiency of 2.5(3) % for SiPMs at cryogenic temperatures

Successful fluorescence spectroscopy of 9Be+ ions in a cryogenic environment

Abstract

We present a fluorescence-detection system for laser-cooled 9Be+ ions based on silicon photomultipliers (SiPM) operated at 4 K and integrated into our cryogenic 1.9 T multi-Penning-trap system. Our approach enables fluorescence detection in a hermetically-sealed cryogenic Penning-trap chamber with limited optical access, where state-of-the-art detection using a telescope and photomultipliers at room temperature would be extremely difficult. We characterize the properties of the SiPM in a cryocooler at 4 K, where we measure a dark count rate below 1/s and a detection efficiency of 2.5(3) %. We further discuss the design of our cryogenic fluorescence-detection trap, and analyze the performance of our detection system by fluorescence spectroscopy of 9Be+ ion clouds during several runs of our experiment.