* In the summer of 1965 the Homestake Mining Company completes excavation of the 30 x 60 x 32 ft cavity at the 4850 ft level that will house the 100,000-gallon chlorine detector proposed by Ray Davis Jr. and his Brookhaven National Laboratory collaborators. Three years later Davis, Harmer, and Hoffman announce the result of their first two detector runs, an upper bound on the solar neutrino flux of 3 SNU (1 SNU = 10^-36 captures/target atom/sec. In an accompanying theoretical paper, Bahcall, Bahcall, and Shaviv present a rate for the standard solar model of 7.5 3.3 SNU. This is the first hint of the solar neutrino problem, and the birth of a new field, neutrino astrophysics.

The collaboration between the Homestake Mining Company and scientists continues over the next three and a half decades as the chlorine result improves in accuracy, and as experiments on cosmic rays and double beta decay are mounted in the mine.

* In the early 1980s Al Mann of the University of Pennsylvania, Bob Sharpe of Los Alamos National Laboratory, and collaborators lead a national effort to create a US underground science laboratory, one modeled on the new European laboratory, Gran Sasso. Despite the growing excitement in the community over solar neutrinos, double beta decay, proton decay, and other underground science, the funding effort is unsuccessful.

* In January 1998 Homestake announces a major staff reduction. Ken Lande, the University of Pennsylvania physicist then leading the chlorine experiment, raises the possibility with Homestake management of eventually converting the mine into an underground science laboratory. In 1999, similar discussions are held with officials from the National Science Foundation and the Department of Energy, and with faculty from the South Dakota School of Mines & Technology, University of South Dakota, and South Dakota State University.

* In the summer of 2000 interest in creating an underground science laboratory in the US is widespread. On June 12-14 the Carlsbad Office of the Department of Energy sponsors a workshop on the advantages of using the Waste Isolation Pilot Plant as the site of a next-generation underground laboratory. In August the DOE's national Institute for Nuclear Theory announces a preTown Meeting on neutrino physics as a first step in the nuclear physics Long Range Plan process. (The Long Range Plan is a once-a-decade exercise of the nuclear physics community in which priorities for the field are set. It is conducted by the Nuclear Science Advisory Committee, which advises the NSF and DOE about nuclear science policy, and the Division of Nuclear Physics of the American Physical Society.) Among the five working groups planned for the September 21-23 meeting is one on underground laboratories.

* The Homestake Mining Company issues a press release on September 11, 2000, announcing the planned closure of the Homestake mine on December 31, 2001.

* Two weeks after this announcement, Lande presents a talk at the Seattle meeting on Homestake's potential as an underground laboratory. Presentations are also given on WIPP, the Soudan Mine, and three sites outside the US, Gran Sasso (Italy), Kamioka (Japan), and the Sudbury Neutrino Observatory (Canada). The first recommendation of the report issued by the 104 physicists attending the meeting includes the following:

"To satisfy the background requirements of new solar/supernova neutrino and double beta decay experiments, the nuclear physics community should spearhead an effort to create a deep underground multipurpose laboratory. Because this national facility could also serve the needs of dark matter and nucleon decay experiments, it is important to involve colleagues from particle and astrophysics. The urgency of one of the proposals (Homestake) requires that the community move now to define the merits and attributes of such a facility."

NSF officials attending the Seattle meeting suggest that the INT and community develop "White Papers" supporting creation of NUSL. INT director Haxton asks John Bahcall, of the Institute for Advanced Study, to chair the committee that will be charged with drafting the white papers. Other members are chosen after consultation with a number of community members. Proposals to support the committee's work are submitted to the NSF and DOE.

* The next level of the nuclear physics Long Range Plan process is a November meeting in Oakland, California, on Astrophysics, Neutrinos, and Symmetries. Lande, Bob Corey, and Sherry Farwell of South Dakota School of Mines and Technology attend that meeting and present the case for Homestake in a lively evening session on underground laboratories. Several particle physicists participate in the discussions. Lande describes the work that he and John Marks (a Homestake engineer) completed in October and early November on operating costs, excavation costs, existing power, ventilation, communications, and cage capacities, and possible upgrades. Farwell describes the strong South Dakota support for Homestake as a science laboratory. Proponents of other proposed sites make similar presentations. The first recommendation of the Astrophysics, Neutrinos, and Symmetries Town Meeting echoes the Seattle report:

"Nuclear physics must build on its successes with low-energy neutrinos by initiating work on the next generation of neutrino experiments. These efforts are not only key to understanding the nuclear physics of stars and supernovae, but could profoundly influence cosmology, astrophysics, and particle physics. Our community must spearhead an effort to create a deep underground multipurpose laboratory that could accommodate the essential new solar neutrino and double beta decay experiments, as well as others of interest to the broader scientific community."

* The first meeting of the Bahcall Committee takes place on December 14, 2000, near Washington, DC. Lande, Farwell, and Steve Mitchell (Reclamation Manager, Homestake Mining Company) attend, with Lande and Mitchell making the Homestake presentation.

* The final meeting of the Bahcall Committee takes place on March 3-4, 2001, in Berkeley, California. This follows an extensive process that involved preproposals submitted by the proponents of various sites, site visits by a Technical Subcommittee headed by Marvin Marshak, University of Minnesota, and a technical report by that subcommittee. The meeting includes presentations by the proponents. Homestake is represented by Stephen Buchholz, Richard Gowen, and Farwell of South Dakota School of Mines & Technology; Lande; and John Osnes of the mine engineering firm RESPEC. The Homestake presentation is given by Gowen, president of SDSM&T.

The Committee calls for the creation of a deep National Underground Science Laboratory, and finds that there are two excellent possibilities, Homestake and San Jacinto, a horizontal access site proposed by physicists from UC Irvine. It recommends a single primary site as the most effective method of realizing the anticipated scientific gains. It favors the Homestake site because of the faster time scale for producing science; the lower initial capital outlay; the greater positive impact on the local population; and lower inherent uncertainties.

The Committee sets two conditions on the recommendation, solution of the Homestake indemnification problem and the involvement of a national group of underground scientists in the preparation of a formal proposal.

* The final meeting of the nuclear physics Long Range Plan process is held in Santa Fe, New Mexico, March 25-30, 2001. The Bahcall Committee report, along with supplementary documents describing the committee's creation, membership, meetings, and other activities, becomes one of approximately 20 "White Papers" submitted to aid the LRP group in its deliberations.

The case for creating a National Underground Science Laboratory is presented by Kevin Lesko (LBNL), John Wilkerson (University of Washington), and Haxton. After considering the merits of eight medium-scale construction projects proposed for the next decade, the underground laboratory is placed first, and becomes the third recommendation overall in the Long Range Plan for nuclear physics:

"We strongly recommend immediate construction of the world's deepest underground science laboratory. This laboratory will provide a compelling opportunity for nuclear scientists to explore fundamental questions in neutrino physics and astrophysics."

The Nuclear Science Advisory Committee follows with a letter to Robert Eisenstein, Director of the Mathematics and Science Directorate, NSF, urging him to proceed with creation of the Homestake laboratory.

* The National Research Council's Committee on the Physics of the Universe hears presentations on the Homestake effort at its May 1-2, 2001, meeting.

* In early June, 2001, a national group of underground scientists -- Janet Conrad (Columbia University), Farwell, Haxton, Marshak, and Wilkerson -- submit a proposal to the National Science Foundation for creation of NUSL-Homestake, with funding to begin in 2003. This is followed by a second proposal for 2002 interim funding. Bahcall agrees to serve as scientific spokesperson for both efforts.

* In July, 2001, an interim collaboration is formed to work toward the creation of NUSL-Homestake while the NSF refereeing process proceeds. The collaboration is open to interested scientists. The interim efforts include establishment of a transition office at the Homestake mine, coordinating land and building transfer with Homestake, preparing a technical design report for underground construction, and outreach activities, including a conference on underground science scheduled for October, 2001.

* In July, 2001, the Long Range Plan process of the high energy physics community begins with a three-week meeting in Snowmass. Presentations on Homestake and underground science are scheduled.