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Data collected by the world’s largest cosmic ray detector available to everyone

The Pierre Auger Collaboration is releasing 10% of the data recorded using the world’s largest cosmic ray detector.

The data collected by the Pierre Auger Observatory, which was founded more than 20 years ago, has helped to unravel some of the enigmas surrounding the high-energy particles occasionally observed, with energies that can exceed 1020 eV (which corresponds to the macroscopic energy of 16 joules ). These particles are predominantly the nuclei of atoms of different elements (from hydrogen to silicon) and reach the Earth from astrophysical sources outside our galaxy.

These data are being made available publicly as open data. This month, the Pierre Auger Collaboration has already made public 10% of the data recorded using the world’s largest cosmic ray detector. According to LIP press release “these data are accessible not only to the scientific community, in several areas ranging from particle physics to astronomy, advanced training in any part of the world, but also to all those who want to use them for educational projects or scientific dissemination”.

In this way, the Pierre Auger Collaboration reinforces its commitment to Open Science: in addition to open access to scientific results, open data and open code are also included, thus promoting open science networks and citizen science. The objective is to increase public access to science, and therefore increase the potential for global development.

The Pierre Auger Observatory Open Data and LIP website include raw data, directly collected by the detectors, but also data already processed by reconstruction and analysis programmes with varying levels of complexity.

As pointed out by the spokesperson, Ralph Engel, “the data from the Pierre Auger Observatory are the result of a vast and long-term scientific, human, and financial investment by a large international collaboration. They are of outstanding value to the worldwide scientific community”.

The role of the Portuguese team in the study of cosmic rays

The Auger Observatory is operated by a collaboration of more than 400 scientists from more than 90 institutions in 18 countries. Portugal became a member in 2006 and, since then, the Laboratory of Instrumentation and Experimental Particle Physics (LIP) has a research group linked to the Pierre Auger Observatory. The Portuguese research team is led by Pedro Assis, Técnico professor at the Department of Physics (DF), and involves several Técnico professors and reseachers from the LIP centres (Universidade de Lisboa, University of Coimbra and University of Minho).

Since 9th May 2017, Instituto Superior Técnico has a remote control room of the Pierre Auger Observatory experiments and the Compact Muon Solenoid experiment. The room is located at LIP headquarters, thus avoiding the need to travel to South America whenever researchers take their shifts. “This room is a mirror of the control room located in the main campus, in the city of Malargue, province of Mendoza, Argentina”, explains professor Pedro Assis. “These shifts are mandatory and essential for the correct operation of the observatory”, adds the Técnico professor.

Due to the COVID-19 pandemic, the room has not been operating regularly. “We considered the possibility of taking shifts from home, but the collaboration requires that we do it in a ‘certified’ room with the right equipment and security for remote connections”, says the Técnico professor. Within a few weeks, the LIP team will conduct remote control operation of fluorescence detectors.

In recent years, the LIP team has been involved in the development of MARTA project, a joint Portugal-Brazil effort to directly measure the muon content in air showers, using resistive plate chamber (RPCs), placed under the Cherenkov detectors. “The water Cherenkov detectors are tanks 1.2 meters high that work as absorbers of other particles and only muons are able to reach the RPCs”, says Professor Pedro Assis.

The LIP team designed some of the Portuguese detectors of Pierre Auger Observatory. “Some detectors at the Pierre Auger Observatory are used to calibrate other detectors that were developed as prototypes of MARTA project. They were used to make experimental installations that allow the calibration of other detectors”, explains the Técnico professor. “Technically they are called hodoscopes and allow to detect passing charged particles and determine their trajectories. Thus, it allows us to understand the response of other detectors to these particles”, adds the team leader.

The LIP team develops its work on understanding the physics of these particles and on improving their detection. “We try to understand what are the first interactions at the top of the atmosphere. For that, it is necessary to model their behaviour and compare to what is expected on the ground”, stresses the DF professor. “LIP has contributed to improving the data collected via new ground detectors, which are important for the development / improvement of the simulations and data analysis tools. We aim to prove the correlation between the initial interaction that occurs at energies exceeding those possible to reach in accelerators and the mark left on the Earth’s surface”, adds the professor.