SPLENDOR

Search for Particles of Light Dark Matter with Narrow-gap Semiconductors

Charge detection is one of the main methods used to search for particle-like dark matter through direct detection. A typical detection scheme involves coupling a semiconductor substrate (e.g. silicon or germanium) to the input of a charge-integrating amplifier. When Dark Matter interacts with the semiconductor substrate, electrons can be excited into the conduction band. An electric field generated by an applied voltage bias then drifts excited electrons towards the input of the charge amplifier. The energy resolution of such a detector is limited by two quantities: the band-gap energy of the semiconductor and the charge resolution of the amplifier. The narrower the band gap, the less energy needed to excite electrons into the conduction band. The lower the amplifier resolution, the fewer electrons needed to detect a pulse.

The SPLENDOR collaboration seeks to develop a semiconductor-independent single-electron-sensitive amplifier and search for Dark Matter using said amplifier with a variety of novel narrow-gap semiconductors. DMQIS has worked with SPLENDOR to develop a classical charge amplifier using low-capacitance cryoHEMTs. This substrate-independent amplifier has demonstrated a world-leading charge resolution of 7 electrons, with potential to achieve single-electron resolution after various improvements. The group is also working on a second-generation charge amplifier using cooper-pair-box transistors (based on the first iteration of a superconducting qubit). This charge amplifier uses quantum phenomenon in superconducting circuits to achieve single-electron resolution.