Developing Sub-eV Ionization Detectors for Dark Matter via IR Optical Fibers and Noise Reduction

We present a novel integration of infrared (IR) optical fiber technology with advanced noise-reduction strategies, showcasing significant progress toward developing low-threshold ionization detectors for dark matter research. Our system utilizes internal charge amplification within germanium (Ge) crystals, enhanced electronic circuit design, and IR optical fibers inside a dilution refrigerator to boost signal sensitivity at low temperatures.



The proposed approach achieves superior electrical noise suppression through optimized circuit architecture and precise cryogenic techniques to minimize thermal noise. Combining these noise-reduction methods with Ge's internal charge amplification, which offers a gain factor of up to 1000, we aim to achieve a sub-eV energy threshold, essential for detecting low-energy ionization events indicative of low-mass dark matter interactions.



Additionally, integrating IR optical fibers facilitates efficient signal transmission within the cryogenic environment, enhancing data acquisition accuracy. Experimental results from the shallow underground laboratory at the Pacific Northwest National Laboratory (PNNL) demonstrate promising improvements in noise reduction, potentially elevating detector performance in the search for low-mass dark matter.