Speakers
Description
Among the proposed Dark Matter candidates, Weakly Interacting Massive Particles (WIMPs) remain particularly compelling, with searches targeting rare keV-scale nuclear recoils.
The only long-standing positive indication compatible with WIMPs has been reported by DAMA/LIBRA at Laboratori Nazionali del Gran Sasso (LNGS). This result is in tension with null findings from more sensitive experiments within the standard WIMP framework, motivating scenarios with target-dependent interactions and stressing the need for independent tests using the same material. Existing and proposed NaI(Tl) experiments (e.g. ANAIS, COSINE, SABRE, PICOLON) rely on photomultiplier tubes (PMTs), which introduce dark noise, limited photon detection efficiency, and intrinsic radioactivity, constraining the achievable energy threshold.
Recent efforts such as ASTAROTH and ANAIS+ have explored replacing PMTs with Silicon Photomultipliers (SiPMs). Besides improved radiopurity and efficiency, SiPMs operated below ~150 K achieve dark noise levels up to two orders of magnitude lower than PMTs.
Background suppression is further enhanced by external veto systems, typically organic liquid scintillators read out by PMTs. However, at LNGS the use of organic scintillators is restricted by safety and environmental regulations.
The ASTAROTH design offers an alternative: the detector operates in a liquid-argon bath for cryogenic cooling, which can be instrumented with additional SiPM arrays and used as active veto. This approach enables background rejection without organic scintillators and represents a novel solution for NaI(Tl)-based experiments.
We present the conceptual design of the ASTAROTH liquid-argon veto, supported by Monte Carlo simulations assessing rejection efficiency and performance. Dedicated cryogenic SiPM readout electronics and the detector layout are described. Since liquid argon scintillates at 128 nm, outside standard SiPM sensitivity, a wavelength shifter is implemented to convert and efficiently detect the emitted photons.
This architecture combines cryogenic SiPM readout with an instrumented liquid-argon veto, providing a scalable and radiopure background-mitigation strategy of interest for future cryogenic rare-event searches.
| Main Contribution topic | Direct detection |
|---|---|
| Secondary contribution topic | Instrumentation for Dark Matter |