Dark Matter Detection: High-Resolution Sensors Probe Sub-GeV Interactions.

Transition-edge sensors, operating with sub-electronvolt energy resolution, demonstrate potential for detecting dark matter in the sub-gigaelectronvolt mass range. Modelling sensor response and applying optimal filtering reveals sensitivity to dark matter-electron and dark matter-nucleon interactions, potentially probing previously unexplored cross-sections with modest exposure times.

The search for dark matter, the invisible substance comprising approximately 85% of the universe’s mass, continues to challenge physicists, particularly in the quest to identify weakly interacting massive particles (WIMPs) with exceptionally low masses. A new analysis details the potential of utilising highly sensitive transition-edge sensors (TESs), superconducting devices that measure minute changes in temperature to detect individual particle interactions, to probe the sub-GeV mass range for these elusive particles. Researchers from the International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (QUP) at the High Energy Accelerator Research Organization (KEK), alongside colleagues from Tohoku University, present their findings in a study led by Muping Chen, Volodymyr Takhistov, Kazunori Nakayama, and Kaori Hattori, entitled “Light Dark Matter Detection with Sub-eV Transition-Edge Sensors”. Their work demonstrates the feasibility of detecting dark matter-electron scattering with unprecedented sensitivity, potentially opening a new window into the nature of this fundamental constituent of the cosmos.Dark matter constitutes a substantial component of the universe, yet its fundamental nature remains elusive, driving vigorous research across particle physics and cosmology. Scientists actively pursue diverse detection strategies, refining theoretical understanding and pushing the boundaries of experimental sensitivity in an attempt to resolve this cosmic mystery.

Researchers initially concentrated on Weakly Interacting Massive Particles (WIMPs), hypothetical particles possessing mass and interacting via the weak nuclear force, as a leading candidate. However, current investigations broaden the scope to encompass a wider range of potential dark matter models, including axions, sterile neutrinos and primordial black holes. Direct detection experiments aim to observe the faint recoil signals produced when dark matter particles interact with ordinary matter. These experiments utilise various detector technologies to maximise sensitivity and capture these elusive interactions. International collaborations such as PandaX, XENON, and SuperCDMS contribute significantly, employing cryogenic detectors and liquid xenon time projection chambers to enhance detection capabilities and gather crucial data.

Theoretical investigations complement experimental efforts, developing predictions for expected signals and considering factors such as particle mass, interaction strength, and potential interactions with both nucleons (protons and neutrons) and electrons. Agrawal et al. (2020) and Nakayama et al. (2018, 2019, 2023) exemplify this work, refining search strategies and interpreting experimental results with increasingly sophisticated models. Understanding the physics of nuclear recoil forms a central component of interpreting direct detection data, as these events represent a primary signature expected from WIMP interactions. When a dark matter particle interacts with an atomic nucleus, it imparts momentum, causing the nucleus to recoil, and accurately modelling these events is crucial for distinguishing them from background noise. Early contributions from Shiles et al. (1980) and Smith et al. (1980) laid the groundwork for this field, while more recent work focuses on refining these models and achieving greater precision in data analysis.

Precise calibration of detectors relies on accurate atomic data, ensuring the reliability of experimental results and minimising systematic uncertainties. Henke et al. (1993) and Gullikson et al. (1993) provided essential data for this purpose, enabling researchers to accurately characterise detector response and calibrate energy scales. Recent research actively pursues high-resolution calorimetric detection of individual energy depositions, utilising transition-edge sensor (TES) technology to achieve unprecedented sensitivity. These sensors operate near the thermodynamic noise limit, offering sub-eV energy resolution and photon-number sensitivity, enabling the exploration of previously inaccessible parameter space for light dark matter.

Modelling TES response, incorporating fundamental noise sources and applying optimal filtering techniques, is essential for maximising sensitivity and probing DM-electron scattering cross sections below $10^{-44}$ cm² for sub-MeV masses. Researchers meticulously characterise detector response and background discrimination for confidently identifying potential dark matter signals. The development of TESs, with their sub-eV energy resolution, offers a promising avenue for probing light dark matter in the sub-GeV mass range and exploring previously inaccessible parameter space. This technology allows researchers to search for dark matter particles with masses and interaction strengths that are beyond the reach of conventional detectors.

The inclusion of publications spanning from 1939 to 2025 underscores the sustained and evolving nature of this research area, highlighting a long-standing commitment to unraveling the mysteries of dark matter. Recent publications, particularly those from 2018 onwards, demonstrate a growing emphasis on low-threshold detectors and advanced data analysis techniques. This reflects a shift towards exploring new parameter spaces and pushing the boundaries of experimental sensitivity.

Future research will likely focus on developing even more sensitive detectors and refining theoretical models to better predict the behaviour of dark matter particles. Scientists will continue to explore a wide range of potential dark matter candidates, including axions, sterile neutrinos, and primordial black holes. The ongoing quest to unveil the nature of dark matter represents a significant scientific endeavour, driving innovation in detector technology, data analysis techniques, and theoretical modelling. This sustained effort promises to unlock new insights into the fundamental constituents of the universe and the forces governing their behaviour.