Muon Tomography sites for Colombian volcanoes

Abstract

By using a very detailed simulation scheme, we have calculated the cosmic ray background flux at 13 active Colombian volcanoes and developed a methodology to identify the most convenient places for a muon telescope to study their inner structure. Our simulation scheme considers three critical factors with different spatial and time scales: the geo-magnetic effects, the development of extensive air showers in the atmosphere, and the detector response at ground level. The muon energy dissipation along the path crossing the geological structure is modeled considering the losses due to ionization, and also contributions from radiative Bremßtrahlung, nuclear interactions, and pair production. By examining each particular volcano topography and assuming reasonable statistics for different instrument acceptances, we obtained the muon flux crossing each structure and estimated the exposure time for our hybrid muon telescope at several points around each geological edifice. After a detailed study from the topography, we have identified the best volcano to be studied, spotted the best points to place a muon telescope and estimated its time exposures for a significant statistics of muon flux. We have devised a mix of technical and logistic rules –the “rule of thumb” criteria– and found that only Cerro Machín, located at the Cordillera Central (4°29'N 75°22'W), can be feasibly studied today through muography. Cerro Negro and Chiles could be good candidates shortly.

Muography in Colombia: simulation framework, instrumentation and data analysis

“…Evidence of that was the Nevado del Ruiz eruption on November 13, 1985, which involved the partial melting of the glacier cap and consequent lahars. Mood flows reached the municipality of Armero-Tolima, causing more than 23000 causalties [6].…”

“…This method uses the attenuation of atmospheric muons after crossing the volcanic edifice. The emerging muon flux measurements at different directions give estimations for the density distributions of volcanic edifices [6]. Several Latin American Universities/Institutions (see Figure 1) work in muography due to the number of active volcanoes along the Andean mountain range and the risk they represent.…”

“…Muography simulation tools & frameworks estimate the atmospheric muon flux [11,12], muon propagation through the geological target [6,13,14], detector response [15,16,17] and density optimisation [18] by using Monte Carlo codes. Development of muography instruments have been addressed from different perspectives.…”

“…to be mainly composed by electromagnetic particles (photons, electrons and positrons) and muons. MUSIC-MUSUN codes [28,29] and Python/MATLAB scripts calculate the ray tracing, the volcano opacity, the muon energy loss, the emerging muon flux and estimates the period of observation [6,30,27]. The code obtains the volcano topography from the SRTM 5 NASA database.…”

A Borehole Muon Telescope for Underground Muography

“…In the muographic field, using compact detectors is advantageous when one wants to carry out direct imaging of underground or buried structures [1,2,3,4,5,6,7]. Unlike Muography applied to volcanoes [8,9,10,11,12,13,14,15,16], where the use of large detectors requires installation in ad hoc structures or in any case in large natural spaces, in underground Muography, the spaces that can be used for the installation of detectors are almost always limited. Examples of these limitations are found almost everywhere in the literature and generally persist even if it is possible to gain space by digging.…”