Observation site
Campaign 2017 at the Cerro Machín Volcano
Characterization of potential observation points
On July 22, 2017, a group of researchers from the MuTe project, together with the expert in volcanology and international advisor to the project, Lilia Arana Salinas (Autonomous University of Mexico), went to the Cerro Machín Volcano with the aim of carrying out a characterization overview of the area where the muon telescope is to be located, to carry out the tomography of the volcano.
Among the activities that were carried out was an inspection of the conditions of the land and of the access roads to the site, as well as the study of the climatic conditions, the characterization of the flow of muons and of the rocks that make up the dome of the Cerro Machín, all of great importance to guarantee the proper functioning of our detector and the successful development of the project.
Weather conditions
The temperature characterization allows the MuTe detector to be calibrated, specifically to ensure the correct operation of Silicon photomultipliers (SiPM), which are devices sensitive to temperature variations. This is why temperature measurements were made for 48 hours using the RACIMO weather station, obtaining a maximum of 16 °C and a minimum of 8 °C as shown in the figure (upper). It should be noted that these measurements were made in the summer season and may decrease in the winter season.
Another variable measured was irradiance, since in the future the MuTe is expected to be a totally autonomous detector, that is, its power source comes from solar energy through a voltaic system. Taking into account only the hours of solar radiation, it was found that the average irradiance in one day is 723 W/m2 (lower figure).
Preliminary muon flux measurements
Measuring the flux of muons from the observation site is necessary in estimating the minimum exposure time of the detector to perform muonography. For this, the prototype of the Mini MuTe hodoscope was taken and it was placed vertically pointing to the zenith, with which 26 continuous hours of data were recorded.
The processing of these data was done offline to determine the number of events (hits) in each of the possible trajectories of the hodoscope.
Fumaroles and dome geology
During the expedition, the presence of fumaroles was observed and rocks were collected at different points of the volcano dome, noting the presence of healthy rock at point M1, moderately altered rock at M2, and highly altered rock at point M3 (figure on the right). These samples will be analyzed by the expert Liliana Arana through petrography, to determine the parameters of density and vesicularity, as well as the respective variations that will serve in the modeling phase of the volcano and the interpretation of the density profile to be obtained with the muography.
