Speaker
Description
Previously proposed dark matter absorption searches using crystalline targets face a fundamental limitation: momentum conservation in a perfect crystal restricts absorption to occur only when the dark matter mass is resonant with one of a small number of optical phonon frequencies. For a dark matter mass hypothesis that doesn't coincide with these narrow resonances, absorption must proceed through heavily suppressed multi-phonon processes, leaving the detector essentially blind to these cases. Amorphous materials, which lack long-range translational order, circumvent this constraint entirely. The continuum spectrum of vibrational modes of amorphous materials means that an absorption mode is always available for a wide range of dark matter masses, yielding a response that is intrinsically broadband. As a result, amorphous targets such as silicon dioxide or silicon nitride can achieve absorption rates one to two orders of magnitude larger than their crystalline counterparts across much of the 50–200 meV$/c^2$ mass range, without the need to build and operate many detectors from different materials, each resonant at a different frequency, to achieve comparable coverage. This talk highlights the theoretical foundation underlying broadband enhancement in dark matter absorption sensitivity with amorphous solids and the proposed detector design for a low-mass dark matter direct detection experimental program.