A Strategy for Low-Mass Dark Matter Searches with Cryogenic Detectors in the SuperCDMS SNOLAB Facility

Abstract

The SuperCDMS Collaboration is currently building SuperCDMS SNOLAB, a dark matter search focused on nucleon-coupled dark matter in the 1-5 GeV mass range. Looking to the future, the Collaboration has developed a set of experience-based upgrade scenarios, as well as novel directions, to extend the search for dark matter using the SuperCDMS technology in the SNOLAB facility. The experienced-based scenarios are forecasted to probe many square decades of unexplored dark matter parameter space below 5 GeV, covering over 6 decades in mass: 1-100 eV for dark photons and axion-like particles, 1-100 MeV for dark-photoncoupled light dark matter, and 0.05-5 GeV for nucleon-coupled dark matter. They will reach the neutrino fog in the 0.5-5 GeV mass range and test a variety of benchmark models and sharp targets. The novel directions involve greater departures from current SuperCDMS technology but promise even greater reach in the long run, and their development must begin now for them to be available in a timely fashion.The experienced-based upgrade scenarios rely mainly on dramatic improvements in detector performance based on demonstrated scaling laws and reasonable extrapolations of current performance. Importantly, these improvements in detector performance obviate significant reductions in background levels beyond current expectations for the SuperCDMS SNOLAB experiment. Given that the dominant limiting backgrounds for SuperCDMS SNOLAB are cosmogenically created radioisotopes in the detectors, likely amenable only to isotopic purification and an underground detector life-cycle from before crystal growth to detector testing, the potential cost and time savings are enormous and the necessary improvements much easier to prototype.This executive summary outlines the detector upgrades, the new dark matter search modes they enable, the resulting expected science reach, and the novel directions under consideration. In the full document that follows, Section 1 reviews the SuperCDMS SNOLAB experiment under construction, including updated sensitivity expectations, along with a high-level overview of future opportunities, both experienced-based upgrades and novel directions. Section 2 provides detailed sensitivity forecasts for the experience-based upgrades. Section 3 presents specific activities being undertaken now to explore the delineated novel directions.

Daily and annual modulation rate of low mass dark matter in silicon detectors

“…Our numerical studies show that the event rate for silicon detectors is similar to germanium at dark matter masses 1 GeV/c 2 . low-mass dark matter experiment with cryogenic detectors [34,43,101], operated at temperatures about some mK in order to damp out thermal noise, it is feasible to distinguish between nuclear recoils and the dominant background, such as photons and electrons that generate electron recoils in the detector.…”

Status and prospects of the SuperCDMS Dark Matter experiment at SNOLAB

“…Optimum Interval (OI) method to a profile-likelihood ratio (PLR) approach with updated detector performance characteristics and background estimates such as crystal bulk contaminants and cosmogenic activation products [6]. Further projections for an upgraded SuperCDMS experiment at SNOLAB as well as bounds presenting the ultimate limit of the technology can be found in [6]. (solid) and previous OI projections (dashed) [5].…”

Even lighter particle dark matter

“…The origin of these events was the focus of the recent series of EXCESS Workshops [43], and likely explanations include phonon bursts induced by stresses in the detector components [44]. Nevertheless, there is active R&D in the further development of these detectors, with future deployments planned for DM searches by EDELWEISS in LSM and SuperCDMS in the NEXUS shallow underground facility at Fermilab, and later in SNOLAB [45].…”