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Matias Tramontini

Publications and source records attributed to Matias Tramontini.

2 recordsLinked to original sources

Atmospheric & geodesic controls on muon rate: a numerical study based on Corsika

Muon rate models play a key role in converting measured data into information on the density distributions of a target. Any given muography measurement, either in transmission or in scattering mode, requires a proper modelization of the muon flux according to the localization and to the atmospheric conditions. Two approaches are commonly used: either through semi-empirical models calibrated on existing data or via Monte-Carlo simulations. The former requires extrapolations to the field experiment conditions while the latter offers the advantage of tackling down in an unique way all relevant parameters such as barometric conditions, geomagnetic field, atmosphere density etc. Although significant progress were made in the last decades, precision muography experiments require more and more accuracy on the models, especially for the muons close to the horizon where large disparities still remain. In this paper we present detailed results obtained with the CORSIKA simulation framework to emphasize and quantify the impact of the environmental conditions on the sensitivity of muography measurements.

physics.geo-ph

Middle-atmosphere dynamics observed with a portable muon detector

In the past years, large particle-physics experiments have shown that muon rate variations detected in underground laboratories are sensitive to regional, middle-atmosphere temperature variations. Potential applications include tracking short-term atmosphere dynamics, such as Sudden Stratospheric Warmings. We report here that such sensitivity is not only limited to large surface detectors under high-opacity conditions. We use a portable muon detector conceived for muon tomography for geophysical applications and we study muon rate variations observed over one year of measurements at the Mont Terri Underground Rock Laboratory, Switzerland (opacity of ~700 meter water equivalent). We observe a direct correlation between middle-atmosphere seasonal temperature variations and muon rate. Muon rate variations are also sensitive to the abnormal atmosphere heating in January-February 2017, associated to a Sudden Stratospheric Warming. Estimates of the effective temperature coefficient for our particular case agree with theoretical models and with those calculated from large neutrino experiments under comparable conditions. Thus, portable muon detectors may be useful to 1) study seasonal and short-term middle atmosphere dynamics, especially in locations where data is lacking such as mid-latitudes; and 2) improve the calibration of the effective temperature coefficient for different opacity conditions. Furthermore, we highlight the importance of assessing the impact of temperature on muon rate variations when considering geophysical applications. Depending on latitude and opacity conditions, this effect may be large enough to hide subsurface density variations due to changes in groundwater content, and should therefore be removed from the time-series.

physics.geo-ph