The data acquisition system of the Latin American Giant Observatory (LAGO)

Abstract

LAGO is an extended cosmic ray observatory composed of water-Cherenkov detectors (WCD) placed throughout Latin America. It is dedicated to the study of various issues related to astrophysics, space weather and atmospheric physics at the regional scale. In this paper we present the design and implementation of the front-end electronics and the data acquisition system for readout of the WCDs of LAGO. The system consists of preamplifiers and a digital board sending data to a computer via an USB interface. The analog signals are acquired from three independent channels at a maximum rate of $ 1.2 Â 10 5 pulses per second and a sampling rate of 40 MHz. To avoid false trigger due to baseline fluctuations, we present in this work a baseline correction algorithm that makes it possible to use WCDs to study variations of the environmental radiation. A data logging software has been designed to format the received data. It also enables an easy access to the data for an off-line analysis, together with the operational conditions and environmental information. The system is currently used at different sites of LAGO.

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

“…The MuTe-WCD (120 cm side) has a Tyvek internal coating and an eight-inch photomultiplier tube (PMT Hamamatsu R5912) as the sensitive element. 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].…”

Enhancing neutron detection capabilities of a water Cherenkov detector

“…In Fig. 4 we show the experimental results from the measurements obtained with the 252 Cf neutron source, in which the contribution of the background has been subtracted [22]. The measurements were made in 300 s and the subtracted background was measured immediately before the source measurements.…”

“…We have built two versions one of 0.5 m 3 and other of a 1.0 m 3 , they consist of a stainless steel commercial water tank of cylindrical shape, with 96 cm of diameter and different heights. Both detectors have 8 "Hamamatsu R5912 PMTs, plus a digitizer board of custom design used by the LAGO Collaboration[22]. The detector is controlled by a Nexys II FPGA with an overall power consumption of less than 8 W. In Fig.1, there is an scheme of the experimental set up, showing the detector characteristics as well as the shielding and source disposition.…”

Calibration and first measurements of MuTe: a hybrid Muon Telescope for geological structures

“…The cubic LAGO-WCD (120 cm side) has a Tyvek internal coating and an eight inch Hamamatsu R5912 photomultiplier tube (PMT) as the sensitive element, which provides two signals (anode and the last dynode), digitized by a 10 bits Fast Analog to Digital Converters (FADCs) with a sampling frequency of 40 MHz [20]. This sub-detector measures (see Figure 2) the energy loss (−dE/dx) of the passing charged particles generating Cherenkov photons and allows the muon/background discrimination, by identifying the EM-component of cosmic ray showers and low energy muons (< 2GeV) which are the main noise sources in muography.…”