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42-557: The experiment took place in the Homestake Gold Mine in Lead, South Dakota . Davis placed a 380 cubic meter (100,000 gallon) tank of perchloroethylene , a common dry-cleaning fluid, 1,478 meters (4,850 feet) underground. A big target deep underground was needed to prevent interference from cosmic rays , taking into account the very small probability of a successful neutrino capture, and, therefore, very low effect rate even with

84-719: A staff of over 130 to the children of mine and mill workers. In the early 1930s, due to fear of cave-ins of the miles of tunnels under Lead's Homestake Mine, many of the town's buildings located in the bottom of a canyon were moved further uphill to safer locations. Lead and the Homestake Mine are the site of the Sanford Underground Research Facility , or Sanford Lab, a NSF facility for low-background experiments on neutrinos, dark matter, and other nuclear physics topics, as well as biology and mine engineering studies. In 1974, most of Lead

126-447: Is 0.814 MeV, i.e. the neutrino should have at least this energy to be captured by the Cl nucleus. Because Ar has a half-life of 35 days, every few weeks, Davis bubbled helium through the tank to collect the argon that had formed. A small (few cubic cm) gas counter was filled by the collected few tens of atoms of Ar (together with the stable argon) to detect its decays. In such a way, Davis

168-645: Is a city in Lawrence County , South Dakota , United States. The population was 2,982 at the 2020 census . Lead is located in western South Dakota, in the Black Hills near the Wyoming state line. The city was officially founded on July 10, 1876, after the discovery of gold . The city was named for the leads or lodes of the deposits of valuable ores. It is the site of the Homestake Mine ,

210-482: Is famous in scientific circles because of the work of a deep underground laboratory that was established there in the mid-1960s. This was the site where the solar neutrino problem was first discovered, in what is known as the Homestake Experiment . Raymond Davis Jr. conducted this experiment in the mid-1960s, which was the first to observe solar neutrinos . On July 10, 2007, the mine was selected by

252-417: Is similarly variable in temperature, as is the spring; however, the fall period tends to be less prone to severe weather. At the 2010 census there were 3,124 people in 1,420 households, including 828 families, in the city. The population density was 1,516.5 inhabitants per square mile (585.5/km ). There were 1,694 housing units at an average density of 822.3 per square mile (317.5/km ). The racial makeup of

294-731: The National Science Foundation as the location for the Deep Underground Science and Engineering Laboratory (DUSEL). It won over several candidates, including the Henderson Mine near Empire, Colorado . Sioux people living near the Homestake deposit knew about gold in the area but did not find it useful. Missionary Pierre-Jean De Smet warned Native people not to tell settlers about the gold, because, "white men would kill every Indian on

336-633: The National Science Foundation over the mine as a potential site for a new deep underground laboratory (DUSEL). But progress was slow and maintaining the pumps and ventilation was costing $ 250,000 per month. The owners switched the equipment off on June 10, 2003 and closed the mine completely. The Homestake Mine was selected in 2007 by NSF for DUSEL, and in June 2009 researchers at University of California Berkeley announced that Homestake would be reopened for scientific research on neutrinos and dark matter particles. In 2010 NSF decided to end DUSEL funding, and

378-399: The 1,279 households 33.2% had children under the age of 18 living with them, 47.8% were married couples living together, 12.4% had a female householder with no husband present, and 34.9% were non-families. 29.2% of households were one person and 11.8% were one person aged 65 or older. The average household size was 2.35 and the average family size was 2.89. The age distribution was 26.1% under

420-868: The 1920s. Charles Washington Merrill introduced cyanidization to augment mercury-amalgamation for gold recovery. "Cyanide Charlie" achieved 94 per cent recovery. The gold was shipped to the Denver Mint . By 1906, the Ellison Shaft reached 1,550 feet (472 m), the B&;M 1,250 feet (381 m), the Golden Star 1,100 feet (335 m), and the Golden Prospect 900 feet (274 m), producing 1,500,000 short tons (1,300,000 long tons; 1,400,000 metric tons) of ore. A disastrous fire struck on 25 March 1907, which took forty days to extinguish after

462-557: The afternoon, but mornings are pleasantly cool: frost-level temperatures occurred in July 1921 and in the Augusts of 1910 and 1911, with August 1910 seeing a freak snowstorm of 1.5 inches or 0.04 metres. The hottest temperature has been 101 °F (38.3 °C) on July 7, 1936, during a notorious Plains heat wave . Precipitation is lower in summer than in spring, and declines further into the fall and winter as temperatures cool. Fall weather

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504-442: The age of 18, 8.5% from 18 to 24, 30.2% from 25 to 44, 22.2% from 45 to 64, and 13.0% 65 or older. The median age was 37 years. For every 100 females, there were 100.9 males. For every 100 females age 18 and over, there were 96.8 males. As of 2000 the median income for a household in the city was $ 29,485, and the median family income was $ 35,855. Males had a median income of $ 25,958 versus $ 18,841 for females. The per capita income for

546-433: The average window for zero temperatures being December 7 to March 3; on the other hand during winter 12.8 afternoons can be expected to get to or above 50 °F or 10 °C. The coldest temperature has been −40 °F or −40 °C on February 8, 1936. During the spring, weather becomes very changeable with frequent severe storms: the first maximum of at least 70 °F or 21.1 °C can be expected on April 17, but

588-468: The city was $ 15,726. About 10.7% of families and 12.9% of the population were below the poverty line , including 15.7% of those under age 18 and 12.9% of those age 65 or over. In the summer, there are numerous trails for hiking, mountain biking, and horse back riding. The George S. Mickelson Trail , which runs from Edgemont to Deadwood, runs through the city. Several man made lakes, including Sheridan Lake provide fishing and swimming. Spearfish Canyon to

630-557: The city was 94.6% White, 0.3% African American, 2.0% Native American, 0.4% Asian, 0.4% from other races, and 2.3% from two or more races. Hispanic or Latino people of any race were 2.9%. Of the 1,420 households 27.6% had children under the age of 18 living with them, 40.6% were married couples living together, 13.0% had a female householder with no husband present, 4.7% had a male householder with no wife present, and 41.7% were non-families. 35.1% of households were one person and 10.8% were one person aged 65 or older. The average household size

672-529: The city. The population density was 1,521.5 inhabitants per square mile (587.5/km ). There were 1,617 housing units at an average density of 812.8 per square mile (313.8/km ). The racial makeup of the city was 95.74% White, 0.23% African American, 2.25% Native American, 0.20% Asian, 0.59% from other races, and 0.99% from two or more races. Hispanic or Latino people of any race were 2.71%. 36.5% were of German , 8.1% English , 7.8% Irish , 7.1% Norwegian and 6.7% American ancestry according to Census 2000 . Of

714-542: The claim from Manuel, Manuel, Engh, and Harney for $ 70,000 in 1877 (~$ 1.85 million in 2023). George Hearst reached Deadwood in October 1877 and took control of the mine property. Hearst arranged to haul the mining equipment by wagon from the nearest railhead in Sidney, Nebraska . Arthur De Wint Foote worked as an engineer. Despite the remote location, deep mines were dug and ore began to be produced. An 80- stamp mill

756-545: The courts. A Hearst employee killed a man who refused to sell his claim, but was acquitted in court after all the witnesses disappeared. Hearst purchased newspapers in Deadwood to influence public opinion. An opposing newspaper editor was physically attacked on a Deadwood street. Hearst realized that he might be on the receiving end of violence, and wrote a letter to his partners asking them to provide for his family should he be murdered. Within three years, Hearst had established

798-578: The end of 2001. Reasons included low gold prices, poor ore quality, and high costs. The Homestake mine released arsenic into the Cheyenne River for decades. Although the area was designated a Superfund site, water was still contaminated in 2017. The Barrick Gold corporation (which had merged with the Homestake Mining Company in mid-2001) agreed in early 2002 to keep dewatering the mine while owners were negotiating with

840-409: The giant open cut, which was used for surface gold mining by the Homestake Mine, and the resulting ridge nearby built with the non-producing material from the cut. Lead has a humid continental climate ( Köppen Dfb ) with warm summers and cold, very snowy winters with the typical extremely variable temperatures of the western Great Plains. Its high elevation in the Black Hills makes Lead one of

882-572: The huge mass of the target. Perchloroethylene was chosen because it is rich in chlorine . Upon interaction with an electron neutrino, a Cl atom transforms into a radioactive isotope of Ar , which can then be extracted and counted. The reaction of the neutrino capture is ν e +   37 C l ⟶   37 A r + + e − . {\displaystyle \mathrm {\nu _{e}+\ ^{37}Cl\longrightarrow \ ^{37}Ar^{+}+e^{-}.} } The reaction threshold

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924-666: The largest, deepest (8,240 feet [2,510 m]) and most productive gold mine in the Western Hemisphere before closing in January 2002. By 1910, Lead had a population of 8,382, making it the second largest town in South Dakota. Lead was founded as a company town by the Homestake Mining Company , which ran the nearby Homestake Mine. Phoebe Hearst , wife of George Hearst , one of the principals,

966-408: The last spring freeze normally does not occur until May 24. The spring is also the wettest season owing to the frequent storms, with the wettest month of May 1965 seeing 14.84 inches (376.9 mm) of precipitation. The wettest year – and a South Dakota calendar year record – has been 2013 with 49.52 inches (1,257.8 mm) and the driest 1936 with 12.84 inches (326.1 mm). Summers are very warm in

1008-611: The mine and acquired significant claims. He walked out alive, and very rich. By the time Hearst left the Black Hills in March 1879, he had added the claims of Giant, Golden Star, Netty, May Booth, Golden Star No. 2, Crown Point, Sunrise, and General Ellison to the original two claims of the Manuel Brothers, Golden Terra and Old Abe, totaling 30 acres (12 ha). The ten-stamp mill had become 200, and 500 employees worked in

1050-709: The mine produced 39,800,000 troy ounces (43,700,000 oz; 1,240,000 kg) of gold and 9,000,000 troy ounces (9,870,000 oz; 280,000 kg) of silver. In terms of total production, the Lead mining district, of which the Homestake mine is the only producer, was the second-largest gold producer in the United States, after the Carlin district in Nevada . Homestake was the longest continually operating mine in United States history. The Homestake mine ceased production at

1092-419: The mine was flooded. Another disastrous fire struck in 1919. In 1927, company geologist Donald H. McLaughlin used a winze from the 2,000 level to demonstrate that ore reached the 3,500 foot level. The Ross shaft was started in 1934, a second winze from the 3,500-foot (1,100 m) level reached 4,100 feet (1,250 m), and a third winze from 4,100 feet (1,250 m) was started in 1937. The Yates shaft

1134-510: The mine, mills, offices and shops. Hearst owned the Boulder Ditch and water rights to Whitewood Creek, monopolizing the region. His railroad, Black Hills & Fort Pierre Railroad , gave him access to eastern Dakota Territory. By 1900, Homestake owned 300 claims, on 2,000 acres (810 ha), and was worked by more than 2000 employees. In 1901, the mine started using compressed air locomotives , fully replacing mules and horses by

1176-624: The plains if they found out about the gold." In 1876, settlers Fred and Moses Manuel, Alex Engh, and Hank Harney discovered the Homestake deposit during the Black Hills Gold Rush . The Black Hills had been guaranteed to the Lakota Nation by the Fort Laramie Treaty , but the land was stolen for its gold. A trio of mining entrepreneurs, George Hearst , Lloyd Tevis , and James Ben Ali Haggin , bought

1218-580: The presence of microorganisms as a banded iron formation . Gold ore mineralization is most intense in the Main Ledge, at the surface, and the 9 Ledge, at the 3200 level (feet below the Incline Shaft, at 1594 m above sea level). 44°21′22″N 103°45′53″W  /  44.3561°N 103.7647°W  / 44.3561; -103.7647  ( Homestake Mine pit ) Lead, South Dakota Lead ( / ˈ l iː d / LEED )

1260-839: The rock, enhancing its permeability to improve thermal energy extraction. The Department of Energy (DOE) began funding basic science with Kismet in 2014, followed by EGS Collab in 2016 and by the Center for Understanding Subsurface Signals and Permeability (CUSSP) in 2023. The gold at Homestake is almost exclusively confined to the Homestake Formation, an Early Proterozoic layer with iron carbonate and iron silicate . The original 20–30 m thick Homestake Formation, has been deformed and metamorphosed , resulting in upper greenschist facies of siderite - phyllite , and lower amphibolite facies of grunerite schists. The iron may have been deposited by volcanic exhalation, perhaps in

1302-703: The site was transferred to the DOE in 2011 as the Sanford Underground Research Facility (SURF), hosting the Large Underground Xenon experiment (LUX), the Majorana Demonstrator, and the Deep Underground Neutrino Experiment (DUNE). The mine is the site for research into enhanced geothermal systems (EGS) with deep access to dense and stable rock. Pressurized water injected inside boreholes fractures

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1344-796: The three "flavours" between which neutrinos are able to oscillate, Davis's detector was sensitive to only one. After it had been proven that his experiment was sound, Davis shared the 2002 Nobel Prize in Physics for contributions to neutrino physics with Masatoshi Koshiba of Japan, who worked on the Kamiokande and the Super Kamiokande (the prize was also shared with Riccardo Giacconi for his contributions to x-ray astronomy). 44°21′12″N 103°44′39″W  /  44.35333°N 103.74417°W  / 44.35333; -103.74417 Homestake Mine (South Dakota) The Homestake Mine

1386-403: The wettest places in South Dakota and among the snowiest places in the contiguous United States with a mean snowfall of 183.9 inches or 4.67 metres. During the cold and snowy winter of 1993–94, a whopping 364.7 inches (9.26 m) of snow fell and three years later snowfall totalled 324.0 inches (8.23 m). However, frequent chinook winds mean that most of the enormous snowfall melts during

1428-431: The winter: the highest snow cover on record is 73 inches (1.85 m) on March 1, 1998 – during a storm that totalled 114.6 inches or 2.91 metres of snow (water equivalent 4.12 inches or 104.6 millimetres) over six days ending March 2. Mean snow depth in January is only 7 inches or 0.18 metres and the median even less at 5 inches or 0.13 metres. 12.9 mornings can be expected to fall to or below 0 °F (−17.8 °C), with

1470-403: Was 2.19 and the average family size was 2.82. The median age was 40.5 years. 23.1% of residents were under the age of 18; 7.4% were between the ages of 18 and 24; 25.3% were from 25 to 44; 31.5% were from 45 to 64; and 12.7% were 65 or older. The gender makeup of the city was 50.3% male and 49.7% female. At the 2000 census there were 3,027 people in 1,279 households, including 832 families, in

1512-439: Was a deep underground gold mine (8,000 feet or 2,438 m) located in Lead, South Dakota . Until it closed in 2002 it was the largest and deepest gold mine in the Western Hemisphere . The mine produced more than forty million troy ounces (43,900,000  oz ; 1,240,000  kg ) of gold during its lifetime. This is about 2,500 cubic feet (71 m ) or a volume of gold roughly equal to 18,677 US gallons . The Homestake Mine

1554-425: Was able to determine how many neutrinos had been captured. Davis' figures were consistently very close to one-third of Bahcall's calculations. The first response from the scientific community was that either Bahcall or Davis had made a mistake. Bahcall's calculations were checked repeatedly, with no errors found. Davis scrutinized his own experiment and insisted there was nothing wrong with it. The Homestake experiment

1596-591: Was added to the National Register of Historic Places under the name of the "Lead Historic District". Over four hundred buildings and 580 acres (230 ha) were included in the historic district , which has boundaries roughly equivalent to the city limits. According to the United States Census Bureau , the city has a total area of 2.06 square miles (5.34 km ), all land. Two prominent manmade features of Lead's geography are

1638-572: Was built, and began crushing Homestake ore by July 1878. In 1879 the partners sold shares in the Homestake Mining Company , and listed it on the New York Stock Exchange . The Homestake would become one of the longest-listed stocks in the history of the NYSE, as Homestake operated the mine until 2001. Hearst consolidated and enlarged the Homestake property by fair and foul means. He bought out some adjacent claims, and secured others in

1680-620: Was followed by other experiments with the same purpose, such as Kamiokande in Japan , SAGE in the former Soviet Union , GALLEX in Italy , Super Kamiokande , also in Japan, and SNO (Sudbury Neutrino Observatory) in Ontario, Canada . SNO was the first detector able to detect neutrino oscillation, solving the solar neutrino problem. The results of the experiment, published in 2001, revealed that of

1722-691: Was instrumental in making Lead more livable. She established the Hearst Free Public Library in town, and in 1900 the Hearst Free Kindergarten. Phoebe Hearst and Thomas Grier, the Homestake Mine superintendent, worked together to create the Homestake Opera House and Recreation Center for the benefit of miner workers and their families. Phoebe Hearst donated regularly to Lead's churches, and provided college scholarships from Lead–Deadwood school which holds

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1764-481: Was started in 1938. Production ceased during WWII from 1943 until 1945, due to Limitation Order L-208 from the War Production Board . By 1975, mining operations had reached the 6,800-foot (2,073 m) level, and two winzes were planned to 8,000 feet (2,438 m). The gold ore mined at Homestake was considered low grade (less than one ounce per ton), but the body of ore was large. Through 2001,

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