Characterizing the neutron component of extensive air showers with the Surface-Scintillator Detectors of AugerPrime

Abstract

Neutrons are the only neutral hadrons that remain stable over the timescale of an air-shower development. Their energy is lost only through hadronic interactions and quasi-elastic scattering, which results in their high abundance at the ground. The signals from the electromagnetic and muonic components in scintillation detectors typically span only a few microseconds. In contrast, the neutrons can cause delayed pulses in scintillation detectors up to and beyond several milliseconds after the passage of the shower front. Selection of an appropriate time window allows us to isolate and characterize the neutron component of air showers, which may provide a new, direct method to probe hadronic interactions during the shower development. We report the measurement of a neutron component at ultra-high energies using the Surface-Scintillator Detectors (SSD) from the AugerPrime upgrade of the Pierre Auger Observatory. We provide a first look at the pulse-amplitude spectrum together with our measured rate and lateral distribution of the neutron component.