The name Canfranc conjures up a variety of associations at once. From the splendor of its international train station to the scenery of the Aragonese Pyrenees. Additionally, the intrigues this municipality encountered while serving as a spies’ hotbed during the Second World War Additionally, Alto Aragon has been linked to the scientific avant-garde since the turn of the 20th century thanks to its underground laboratory, an international reference facility located in the Somport tunnel, which connects Spain and France, beneath 800 meters of the rock that makes up Mount Tobazo. This built-in shield enables researchers to study rare particles like neutrinos, which can shed light on the origins of matter, bring light and dark matter closer together, or explain how living things grow in the absence of radiation. It will suffice to say that, despite having a permanent staff of only about thirty people, its facilities are home to over 250 researchers from 51 centers and eleven different nationalities. Furthermore, it conducts innovative studies that give this laboratory a distinct advantage. Carlos Pea Garay, the director of the Canfranc Underground Laboratory (LSC), claims that it is “unique in Spain and the second most significant in Europe; it is a jewel to have a facility like this, which attracts scientists and engineers from all over the world.”
This center was established in 1985 at the initiative of researchers from the University of Zaragoza. The Nuclear Physics research group of the Aragonese Campus chose the location between the current road tunnel and the old railway tunnel, which has been vacant since the 1970s, to set up what is now this laboratory. It has since been expanded and renovated, and at this time it is the second largest structure of its kind in Europe. In addition, like the Mare Nostrum supercomputer in Barcelona or the Gran Telescopio de Canarias, the LSC is regarded as an ITCS, or a Singular Technical Scientific Facility. The center is currently run by a partnership between the Ministry of Economy and Competitiveness, the Government of Aragon, and the University of Zaragoza. In this exceptional setting, up to twenty experiments in physics, biology, geology, and other fields of science are conducted. The director explains that when scientists and engineers construct extremely sensitive detectors, they will primarily measure cosmic rays on the surface. “You have to protect them, and that’s what we do by putting some ground in the way, to be able to use these detectors and discover new phenomena or characterize them in high sensitivity,” he continues. He describes it as being similar to a pair of sunglasses or an umbrella that blocks out cosmic noise.
A shield of 800 meters of rock that, for instance, makes it possible to conduct the NEXT experiment, the most significant experiment currently taking place at the LSC. Its primary goal is to show that neutrinos “have a very unique quality in that they are both matter and antimatter simultaneously, according to Pea. By proving that they are matter and antimatter, the scientist continues, “we could explain and understand how the universe, in the first fraction of a second, was able to form a little more matter, which is us, and not our alter ego, which is antimatter.” Since its nucleus “has a very rare and special disintegration, it emits two electrons at the same time,” xenon 136, a “very special” gas, is used by NEXT to accomplish this. According to the center’s director, this emission also contains “two particles that we know less about and that are like ghosts.” Neutrinos, then. The other main initiative of the center is the ANAIS project, which is being led by Marisa Sarsa, a researcher at the University of Zaragoza. According to Pea, “In this case, it’s looking for a part of the matter that is very different from the one we are,” This is dark matter, which makes up at least 84% of the universe’s mass. He claims, “We can’t see it, but we know it exists because we can feel it through gravity.
The goal of this project is to confirm or disprove an Italian experiment called DAMA/LIBRA that “observed a signal compatible with the existence of dark matter,” according to the director. The experiment used sodium iodide crystals. He says, “Anais is competing with two other experiments in the world – one in South Korea and one in the United States – and, in fact, it is the one with the lead. Pea illustrates how the LSC extends beyond these two eminent research initiatives and is set up as “a hotel for experiments with a lot of services.” In order to study what happens to life when cosmic radiation and muons, a charged particle 200 times more massive than an electron, are absent, the center is leading the development of these fields. When asked about the laboratory’s future and speaking of biology, the director responds as follows: “The future is generally extinction, which is one of the most fascinating things you learn in biology. And he continues, “Everything, as a human creation, will eventually go extinct and stop making sense; we will only exist while we do, that is, while we have that utility, which is to serve a scientific community that has inventions and where having a resource like this one is crucial or necessary.”
A future that includes, among other things, serving as the center in charge of organizing Spain’s contribution to the Hyper-KamioKande, a massive Japanese experiment that aims to expand our understanding of neutrinos and their characteristics. A massive ultrapure water tank measuring 68 meters in diameter and 71 meters in height will be installed in Japan in a location resembling the LSC as part of this project. According to Pea, “in that darkness we will be able to see neutrinos coming from stars and by looking at those neutrinos we will be able to find out what is happening inside them.” Spain will contribute “3% of the total budget,” with 10% of that going toward the construction of the detector, and the Canfranc laboratory will coordinate those actions. There is a lot of industrial work; 75% of the budget goes to our industry, which will produce the components we will ship to Japan.