The synchronisation of the AMIGA muon detector

RAVIGNANI, D.; SANCHEZ, F.; ALMELA, A.; ANDRADA, B.; BOTTI, A.; FIGUEIRA, J.; GARCIA, B; GONZÁLEZ, N.; JOSEBACHUILI, M.; MELO, D.; TAPIA, A; WAIMBERG, O.; WUNDHEILER, B.; ETCHEGOYEN, A.

2014-01-01/2015-09-30

1-12

Electrónica

Prom.Gral.del Conoc.-Cs.Exactas y Naturales

The timing of the signals recorded by the muon detector (MD) will extend the scientificreach of AMIGA to applications like the reconstruction of the muon production depth(MPD) and of the event geometry. The MPD can be measured from the arrival time ofmuons at the MD counters. The electromagnetic component of the air shower is mostlyfiltered out by 2.3m of soil shielding, entailing a minimum energy of 1 GeV for verticalmuons. The high purity of the MD signals allows using all triggered counters but thosevery close to the core. At 2.3m underground our simulations estimate less than 1% ofelectromagnetic contamination beyond 100 m. This distance is significantly lower than 1700 m, the limit to select a detector for the MPD reconstruction in the SD analysis. In events observed simultaneously by the SD and the MD, the relaxation of the cut distance will enhance the MPD reconstruction with the enlarged muon sample provided by the MD data. Furthermore, more muons will enable the MPD measurement down to 0:3 EeV, the threshold energy for full trigger efficiency of the Infill. At higher energies the analysis will be limited by the number of events that can be observed given the 23:5km2 of area planned for the MD array.The MD time information will be also used to reconstruct the event geometry. The high energy muons reach the buried MD counters earlier and less dispersed than other shower particles. Muons provide a time observable that can be combined with the SD signal starttime to reduce the uncertainty in the measured arrival directions. Since time dependant applications were beyond the original AMIGA scope of measuring the number of muons, the MD detector was built without the hardware needed to time signals standalone. We overcame this limitation by exploiting the stable delay of a MD module with respect to its linked SD station. Based on the trigger sent by a SD station to the attached modules, we synchronised the MD. The synchronisation signal was provided by events observed in coincidence by both detectors