Design and construction of MuTe: a hybrid Muon Telescope to study Colombian volcanoes

Abstract

We present a hybrid Muon Telescope, MuTe, designed and built for imaging active Colombian volcanoes. The MuTe has a resolution of tens of meters, low power consumption, robustness and transportability making it suitable for using in difficult access zones where active volcanoes usually are. The main feature of MuTe is the implementation of a hybrid detection technique combining two scintillation panels for particle tracking and a Water Cherenkov Detector for filtering background signals due to the electromagnetic component of extended air showers and multiple particle events. MuTe incorporates particle-identification techniques for reducing the background noise sources and a discrimination of fake events by a picosecond Time-of-Flight system. We also describe the mechanical behavior of the MuTe during typical tremors and wind conditions at the observation place, as well as the frontend electronics design and power consumption.

Simulated Annealing for volcano muography

“…Notice that there are regions where the incoming muon flux is absorbed due to the volcano's geometry, and some of the distances travelled could easily exceed 900 meters. The statistics of 100 muons/pixel for the above MuTe configuration is consistent with other more realistic studies ( see references (Vesga-Ramírez et al, 2017;Vásquez-Ramírez et al, 2019b;Peña-Rodríguez et al, 2020;Moss et al, 2018) for further details).…”

“…In this section, we briefly describe our hybrid Muon Telescope, MuTe, and the selected muography observation site at Cerro Machín in the department of Tolima. Details of the instrument operation and calibration are considered in (Vásquez-Ramírez et al, 2019b;Peña-Rodríguez et al, 2019;Peña-Rodríguez et al, 2020), while the reasons in choosing Cerro Machín among 13 other Colombian volcanoes can be found in reference (Vesga-Ramírez et al, 2017).…”

“…where r m,n represents each discrete muon incoming direction. The total angular aperture of the telescope (considering both panels and the WCD) with this configuration is roughly 50 • (0.9 rad) with a maximum solid angle of 1.024 × 10 −3 sr at r 0,0 , and the largest detection area approximating 5.759 cm 2 sr at r 0,0 (see reference (Peña-Rodríguez et al, 2020) for details).…”

Characterization of the muography background using the Muon Telescope (MuTe)

“…The anode and last dynode PMT signals are digitized by a 10-bit fast Analog-to-Digital converter with a sampling frequency of 40 MHz [13]. The ToF system (∼97 ps resolution) is based on a Time-to-Digital converter implemented on a Xilinx FPGA Spartan 6 [14]. The MuTe data acquisition system is temporally synchronized by GPS.…”

“…The incident particle momentum was estimated using the ToF measurements, the trajectory reconstruction, and the particle mass [14]. We set a threshold to reject particles with momentum below 1 GeV/c as shown in Figure 5-left.…”