Construction and Science of SURF

Abstract

The Sanford Underground Research Facility (SURF) began operation in 2007 as a facility dedicated to advancing compelling multidisciplinary scientific research. SURF is one of the deepest laboratory sites and offers the largest footprint in the world for scientific pursuits, including physics campuses on the 4850-foot level where the LUX-ZEPLIN, MAJORANA DEMONSTRATOR, and CASPAR experiments are located. SURF is also home to the Long-Baseline Neutrino Facility (LBNF) that will host the international Deep Underground Neutrino Experiment (DUNE). SURF provides ultra-low background environments, low-background assay capabilities, and electroformed copper is produced at the facility. In this review, we discuss the history, features and status of the facility, as well as the current scientific program and future evolution and plans.

Figures (6)

• Figure 1: The size (volume of science space) and effective shielding depth (total muon flux) for the main global deep underground facilities are represented according to geographic location. The far left-hand side shows the current state and future of SURF, where the dark-blue circle represents the current combined size of 4850L laboratories. The SURF strategic plan aims to provide additional lab space on the 4850L as well as the possibility of a deeper site on the 7400L as indicated by lighter shaded blue circles. Some muon-flux values are estimated using a recent parameterization JNE:2020bwn.
• Figure 2: Simplified view of SURF's geography, including the main underground elevations for science and the two operating 4850L campuses; the location of the 4850L LBNF Campus is also indicated.
• Figure 3: (a) SURF current and proposed underground laboratory space on the 4850-foot level. Two new caverns in green are shown (100 m L $\times$ 20 m W $\times$ 24 m H) with a rock overburden similar to existing laboratories (1500 m, 4200 m.w.e.); Phase A Expansion excavation is complete. (b) Ross Campus: four existing excavations are labeled NW, NE, SE, SW. The two western shop areas are currently in use as laboratories, whereas the two eastern shops are presently used for non-scientific purposes. (c) Davis Campus: the main laboratory spaces and supporting areas are shown, including the proximity to the Yates Shaft. An asterisk indicates the location for the proposed Quantum User Facility (see Section \ref{['sec:quantum_user_facility']}).
• Figure 4: Conceptual drawing of the SURF 4850L Expansion Campus, with up to two 100-m-long caverns (20 m wide $\times$ 24 m high). As shown, the space could allow for 1--2 large experiments as well as several mid-size experiments. Preparations necessary for embarking on this new excavation have been completed.
• Figure 5: Proposed SURF Quantum User Facility located in a Davis Campus laboratory space that previously supported the Majorana Demonstrator. Some facility cooling and electrical modifications will be necessary and could begin in 2026.