Deeper understanding at Lab 2:the new experimental hall at Callio Lab underground centre for science and R & D in the Pyhäsalmi Mine, Finland

In this work I introduce Callio Lab, an underground centre for science and R & D in the Pyhäsalmi Mine, Finland, and the new underground measurement hall Lab 2. Furthermore I present the world’s deep underground laboratories (DULs). In addition I cover the main sources of the background radiation for underground laboratories including their effects to specific low background research topics. As a case study I describe the required steps for the concretisation of a deep underground measuring hall and the methods to reduce the radiative background in Lab 2, especially related to radon. Callio Lab is one of the few deep underground laboratories in the world offering facilities with over-burden of more than 2 000 m.w.e (metres water equivalent), maximum being at 4 000 m.w.e. The deepest currently operating facilities are in Canada (SNOLab, 6 000 m.w.e.) and China (JingPing underground laboratory, 6 800 m.w.e.). The new experimental hall Lab 2 is located at the depth of 1 430 m (approx. 4 000 m.w.e.) in the Pyhäsalmi Mine. The overburden makes the Lab 2 an optimal site for low (muon) background experiments. The value is based on the measurements presented in the Measurements of muon flux in the Pyhäsalmi underground laboratory (T. Enqvist et al., NIM A 554, 2005). Lab 2 was finished during the spring 2016. The Lab 2 consists of two halls: the entrance hall (120 square metres) for handling cargo and the experimental hall (120 square metres). My involvement in the realization of the Lab 2 started in spring 2015 with the preliminary design and ended with the final design. During the design phases I contacted several Finnish suppliers to find documented, low background construction materials to be used in the construction. At the end of the construction I was also involved in the instrumentation of the experimental hall. In the preliminary design the idea was to build a low background experimental hall using low background materials. As these materials were rather expensive the requirements had to be lowered. The main background source in the Lab 2 is the shotcrete walls and the ceiling due to relatively high concentration of uranium and thorium in the additive used in the concrete. Radon, Rn-222, emanating from the surrounding rock and concrete is the biggest challenge for the low background experiments. The radon is radioactive, noble gas and it can diffuse into every setup. The problem comes with the radioactivity of radon, as also the progenies of radon are radioactive all the way to the stable Pb-206. Other DULs have also been challenged by the radon contamination, and several methods have been developed to mitigate the radon levels. Based on the example radon traps presented in the Low background techniques and experimental challenges for Borexino and its nylon vessels (A. Pocar, Ph. D. Thesis, Princeton University, 2003), a decision was made on the type of a radon trap most suitable for Lab 2. I made a schematic design for an active radon trap, a pressure swing adsorption filter. Although first experiment, C14, is already using the Lab 2, background screening of the site has to be performed to fully understand the different background sources. This would help to define what kinds of experiments are feasible to be hosted in the Lab 2, and to define the types and thicknesses of radiation shielding needed for these experiments

Trends in publishing muography related research:the situation at the end of 2020

Abstract Cosmic-ray muography is a novel method for density characterization of gaseous, solid, and liquid materials in various dimensions and with numerous distinct technologies. The number of applications of muography is on a constant rise, as is also the number of authors, affiliations, journals, publishers, funding agencies, and countries that can be related to muography literature. We have applied the Web of Science global citation database to collect statistics of muography-related publications to draw a snapshot of where muography was at the end of 2020, how it got there, and where the current trends may get it in the future

Trends in publishing muography related research results:the situation at the end of 2020

Abstract Cosmic-ray muography is a novel method for density characterization of gaseous, solid, and liquid materials in various dimensions and with numerous distinct technologies. The number of applications of muography is on a constant rise, as is also the number of authors, affiliations, journals, publishers, funding agencies, and countries that can be related to muography literature. We have applied the Web of Science global citation database to collect statistics of muography-related publications to draw a snapshot of where muography was at the end of 2020, how it got there, and where the current trends may get it in the future

Muography, outreaching, and transdisciplinarity:toward the golden age of muography

Abstract We demonstrate that cosmic-ray muography is a fundamentally multidisciplinary research field requiring an outreaching and transdisciplinary approach to support and speed up its current positive growth stage. The transit from expert-driven multidisciplinary research to interdisciplinary and transdisciplinary research requires publishing and promoting muography on multiple fronts and languages. Still, as the rewards for the muography community are likely great indeed, we call for collaborative actions and a change in the research strategy paradigm. Due to this end, we suggest a list of task points for the presentday muography community to get muography better acknowledged and as appealing as possible for the newcomers interested in developing muography or applying it in their respective applications

Thoughts about an ideal validation environment for muography applications

Abstract Muography has many possibilities ranging from imaging volcanoes to observing civil infrastructures, industrial targets, or even small-scale objects. G. F. Knoll has laid out the fundamentals of radiation detection and measurement of muon flux. However, what is still lacking is the testing and verification environments for muon detectors used in muography. This work will present a few thoughts on such a possible muography test and method validation site in terms of micro and macroscale validation environments and introduce one candidate location, Callio Lab, Finland

Callio Lab:the deep underground research centre in Finland, Europe

Abstract Pyhäsalmi, in the Town of Pyhäjärvi, hosts one of the northernmost deep underground laboratories in Europe, the Callio Lab. Its origins are in underground physics (Centre for Underground Physics in Pyhäsalmi, CUPP), but gradually it has turned into a multi- and transdisciplinary research environment utilising both the surface and underground. Besides research, the infrastructure is open for business and innovation under the Callio — Mine for Business. The pre-investment for an underground pumped-hydro storage facility to be built at the area utilising the existing tunnel network for construction has been made. This investment ensures the existing and future utilisation of the underground and surface facilities

Callio Lab:the deep underground research centre in Finland, Europe

Abstract Pyhäsalmi, in the Town of Pyhäjärvi, hosts one of the northernmost deep underground laboratories in Europe, the Callio Lab. Its origins are in underground physics (Centre for Underground Physics in Pyhäsalmi, CUPP), but gradually it has turned into a multi- and transdisciplinary research environment utilising both the surface and underground. Besides research, the infrastructure is open for business and innovation under the Callio — Mine for Business. The pre-investment for an underground pumped-hydro storage facility to be built at the area utilising the existing tunnel network for construction has been made. This investment ensures the existing and future utilisation of the underground and surface facilities