Underground physics without underground labs: large detectors in solution-mined salt caverns

Abstract

A number of current physics topics, including long-baseline neutrino physics, proton decay searches, and supernova neutrino searches, hope to someday construct huge (50 kiloton to megaton) particle detectors in shielded, underground sites. With today's practices, this requires the costly excavation and stabilization of large rooms in mines. In this paper, we propose utilizing the caverns created by the solution mining of salt. The challenge is that such caverns must be filled with pressurized fluid and do not admit human access. We sketch some possible methods of installing familiar detector technologies in a salt cavern under these constraints. Some of the detectors discussed are also suitable for deep-sea experiments, discussed briefly. These sketches appear challenging but feasible, and appear to force few major compromises on detector capabilities. This scheme offers avenues for enormous cost savings on future detector megaprojects.

Kiloton-scale xenon detectors for neutrinoless double beta decay and other new physics searches

“…However, solutions in which the cavern itself provides the mechanical support for a thin walled Xe vessel may be possible. In addition to conventionally mined caverns, such possibilities include use of a solution-mined salt cavern that would naturally support the required pressures [142].…”

Kiloton-scale xenon detectors for neutrinoless double beta decay and other new physics searches

“…However, solutions in which the cavern itself provides the mechanical support for a thin walled Xe vessel may be possible. In addition to conventionally mined caverns, such possibilities include use of a solution-mined salt cavern that would naturally support the required pressures [138].…”

Sub-Penning gas mixtures: new possibilities for ton- to kiloton-scale time projection chambers

“…Most conventional detector-design considerations (materials, radioactivity budgets, readout details) are neglected unless we feel there is a sub-Penning-specific aspect worth commenting on. For the specific engineering complexities of solution-mined salt caverns, we refer the reader to [20]. While acknowleding that the concept is far from proven, we hope that these detector sketches provide motivation for further engineering studies on those caverns as well as on the gases themselves.…”

“…2. Placing an inflatable xenon balloon in a solution-mined salt cavern as discussed in [20]. An example of the successful construction and filling of a thin-balloon detector can be found in [24].…”