Located just below the Polar circle, Callio Lab is one of the northernmost underground laboratories in Europe [1,2]. The underground research centre has developed from underground physics (formerly known as the Centre for Underground Physics in Pyhäsalmi, CUPP ). Over the years, its strategy has been shifted to a multi-and transdisciplinary research centre, now known as Callio Lab.
The Callio Lab is physically located at the 1.44 km deep Pyhäsalmi mine, Pyhäjärvi, Finland. The mine has produced copper, zinc and pyrite since its opening in 1962. The deposit is geologically located within a 1.9 bn-year-old seafloor and belongs to the class of volcanic massive sulphide (VMS) deposits . Seismically the bedrock is stable and tremors are mainly induced by the mining activities. The mine has a flat overburden, and access to the mine is through an 11 km incline or the 1.4 km deep elevator shaft. The travel times are 30 minutes and 2.5 minutes, respectively .
The development of underground research facilities in the Pyhäsalmi mine started in the late 1990s at the margin of the then known ore resources. However, with the discovery of a new deposit below the old one, the life span of the underground mining was extended year by year. However, it is expected that mining will cease at the later part of 2021. The eventual end of underground extraction will give more room and possibilities for science, research and business. The latter is governed by the Callio – Mine for business , governed by the local town. The scientific activities of Callio Lab are coordinated by the University of Oulu, Finland.
Throughout the years the various scientific activities and research initiatives have been started at the Callio Lab. The characterisation of underground halls (i.e., Labs in the facility) has included the on-site natural background radiation measurements (gamma, neutron, radon) and sample analysis of the building materials used and samples of the surrounding bedrock [7–12]. The muon background measurements were done in 2005 . The rock overburden at a depth of 1390 has been measured to be 4000 m.w.e., and at Lab 2, located at a depth of 1436m, it is estimated around 4100 m.w.e .
The scientific activities at utilising the Callio lab research infrastructure range from mining and mining-related training to geothermal concept and technology testing, underground food production, working environment research, and particle physics. The low-background facility, using the low background HPGe detector from Baltic Scientific Instruments, is located at Lab 5 at a depth of 1410 m. . The facility provides sample analysis services for the EUL project laboratories , but other scientific institutions benefit from the facility too.
Callio Lab is part of the DULIA network, a founding member of the European Underground Laboratories association , a candidate as a thematic core service for the European Plate Observation System, EPOS , member of Nordic and Finnish EPOS research infrastructures, and is a strategic research infrastructure of the University of Oulu. EPOS is on the European and Finnish research infrastructure roadmaps.
This work has been supported by grants by the Interreg Baltic Sea programme and Nordforsk.
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