The Pierre Auger Observatory is located in the city of Malargüe, 422 km to the south of the city of Mendoza.
In November 1995, the UNESCO chose Argentina as the south site of the project. One of the reasons was that the zone known as Pampa Amarilla, in Malargüe, is a plain which, apart from allowing the installation of the detector tanks in an extensive zone, is located high above sea level, providing a clean sky where the particles can be detected more easily than in other regions. Besides, the infrastructure of the place and the support of the government and of scientists, both at national and provincial level, were determining factors at the time Argentina was selected.
The Pierre Auger undertaking is the only one in the world designed to specifically study the origin and the reason of the cosmic rays, something which will allow us to better understand the creation process of the universe.
The observatory of the north hemisphere will be mounted in Utah, United States.
It is a joint undertaking of more than 20 countries, in which about 250 scientists of more than 30 institutions participate, with the purpose of detecting subatomic particles which come from outer space and which are called cosmic rays. Some of these rays have such a high energy that, according to present knowledge, they could not exist in the universe. The energy in one of these particles is a hundred million times higher than the one that can be imparted to a subatomic particle in one of the most powerful accelerators that has been built so far. It is estimated that in a century only one of these particles arrives to each square km of the Earth’s surface, so its detection is extremely difficult.
For this reason, the observatory consists of a network of 1,600 detectors, assembled in the building of Malargüe and separated 1.5 km each, covering a total surface of 3,000 sq km, 20 times the surface of Paris. The network of surface detectors is complemented by a set of 24 telescopes of high sensitivity. The detectors consist of big closed cylindrical tanks, of approximately 3.5 m of diameter and more than 1.5 m of height, which contain an also cylindrical polyethylene bag, manufactured by local students on site who follow the directives of the University of Colorado. This bag contains 12,000 liters of ultra pure water in which the particle leaves its trace. Each tank is independent and operates with solar energy. The instruments of each detector measure the number of particles that go through them. The particles of the cascade produced by a cosmic ray of high energy reach several detectors almost at the same time. When the particles crash a station, a computer establishes a radio communication with neighboring stations so as to decide if the particles are part of a cascade. In this case, the information of the cascade is transmitted by radio to a data collector center. In this center, the computers combine the characteristics of the particles and their time of arrival to each station in order to determine the direction and energy of the original cosmic ray which originated the cascade.
The total cost of the project is of about 100 million dollars, and its maintenance costs about 2.5 million dollars per year. The province of Mendoza –Argentina, Brazil, France, Germany, Italy, México and the United States are those who most economically contribute to the project.
Argentina is in charge of building 500 surface detectors, its electronics, the battery cases and the supporting structures for the solar panels, the buildings, the telecommunication towers and the anthems of each detector, their internal bags and the ultra pure water they contain, the location of the detectors, and the cartography and development of the location. Argentina contributes with the adjustment of the instruments, including the electronics of the telescopes and detectors, with the management of the project and of the observatory, and it will be fundamentally responsible for the operation and maintenance of the observatory during its estimated 20 years of operation. Together with Brazil, it is in charge of the data analysis program and it is building a data storage center in the Centro Atómico Constituyentes. Argentina is also carrying out a training program for young scientists and engineers.
It is estimated that in a period of about 10 years the Auger project will have registered more than 600 cosmic rays of an energy higher than 1020eV, a number possibly enough so as to individualize the sources, which must originate in well localized regions of the universe.
The building, where news spreading tasks are also carried out, is furnished with modern equipment for the projection of audiovisuals and videos. It is estimated that its facilities are visited by about 5,000 people per year, guided by a specialist who comments on the purpose and importance of the observatory.
The management of the undertaking is in charge of James Cronin, from the University of Chicago, Physics Nobel Prize in 1980, Emeritus Director; Alan Watson, from the University of Leeds, United Kingdom; and Hans Bluemer, from the University of Karlsruhe, Germany.
Source: Pierre Auger Observatory
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